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awesome projects by On sale 24 August to 23 September, 2019 Our very own specialists are developing fun and challenging Arduino® - compatible projects for you to build every month, with special prices exclusive to Club Members. PROJECT OF THE MONTH: Wi-Fi photo frame Share your memories or get the latest in memes automatically with this Wi-Fi enabled photo frame. Using our newest UNO board with Wi-Fi and a 320x240 touch screen, all you need to do is to provide a list of JPEG links and the photo frame will rotate through and display them automatically. Can be used with the popular service IMGUR to get daily content automatically. NERD PERKS BUNDLE DEAL 4995 $ SKILL LEVEL: Intermediate TOOLS: Soldering Iron SAVE 25% SEE STEP-BY-STEP INSTRUCTIONS AT: www.jaycar.com.au/wifi-photo-frame WHAT YOU NEED: KIT VALUED AT: $69.90 1 × UNO Board with Wi-Fi XC4411 $39.95 1 × 240x320 LCD Touch Screen XC4630 $29.95 See other projects at www.jaycar.com.au/arduino Make your project portable ONLY 4 $ 95 4 XC 40 6 Secure mounting of 2 x 18650 batteries. 150mm leads. ABS plastic. PH9207 Full range available in-store or online 08 SB231 3 FROM ONLY FROM Clear acrylic enclosures for Arduino® Lithium battery USB charger module Li-ion rechargeable batteries 495 $ Dual battery holder SB23 Protect your Arduino board against damage, dust and scratches. Pre-drilled to provide easy access to all ports. Suits UNO Board XC4406 $4.95 Suits MEGA Board XC4408 $6.95 25% OFF 495 $ Charges a single lithium cell from a 5V supply. Output via solder tabs, input is either via solder tabs or a mini-USB port. XC4502 1595 $ 18650 Li-Ion battery, commonly used in LED torches and some Tesla electric vehicles. 2600mAh 3.7V. Nipple Tag SB2308 $15.95 Solder Tag SB2313 $17.95 Full range available in-store or online exclusive club offer your club. your perks! SHORT CIRCUIT PROJECTS* Keep up to date with the latest offers and what’s on! visit www.jaycar.com.au/makerhub *Applies to Vol 2 & 3 project kits & instruction. Books not included. Shop the catalogue www.jaycar.com.au 1800 022 888 Contents Vol.32, No.9 September 2019 SILICON CHIP www.siliconchip.com.au Features & Reviews 16 History of Cyber Espionage and Cyber Weapons, Part 1 The spooks have been using some ingenious methods to spy on each other over the years. Here we look at just some of those methods and the equipment they used – by Dr David Maddison 42 ElectroneX 2019 – Melbourne, September 11 & 12 Australia’s only dedicated electronics design and assembly expo is on this month at Melbourne’s CEC. Register online for free admission at electronex.com.au 69 Restoring a Macintosh Classic II First released in 1991, the Classic II (also called a Performa 200) was a real challenge to bring back to life nearly 30 years later! – by Bruce Rayne They go to amazing lengths to spy on each other: the USS Jimmy Carter is reputed to be able to tap into undersea cables! – Page 16 92 Cypress “system on a chip” revisited A follow-up to our October 2018 article on the Cypress CY8CKIT-049-42XX PSoC – this time featuring the more powerful CY8CKIT-059 board – by Dennis Smith Constructional Projects 26 Build your own Gamer’s Seat with Four DoF If you’re into computer gaming, you’ll know that nothing beats a seat that echoes your screen movements. But they’re very expensive to buy! This D-I-Y version is driven by a Micromite and has four degrees of freedom – by Gianni Pallotti 52 A new Micromite: the sensational Explore-28 With an inbuilt USB socket, you can simply plug the Micromite Explore-28 into your PC and start programming. And it’s tiny: just 40mm x 19mm x 8mm and features 19 I/O pins (of which 10 are capable of analog input) – by Geoff Graham Micromite controlled D-I-Y Gamer’s Chair offers four degrees of freedom. Bring your on-screen games to life – Page 26 New Micromite Explore-28: even more features including an on-board USB programming socket – Page 52 74 Six-way Stereo Audio Input Selector with remote control Sometimes one or two inputs just aren’t enough! This new audio selector can handle up to six stereo inputs which can be selected by push button or remote control. And it even offers remotely controlled volume! – by John Clarke 100 Ultrabrite LED Bicycle Light You must have noticed some of those really bright white LED lamps on some of today’s pushbikes. Here’s one you can build yourself and $ave money. It has brightness settings, flash settings and much more – by Daniel Doyle Need more audio inputs? How about six? Remote controlled or push button and the volume control is remote controlled too! – Page 74 Your Favourite Columns 86 Serviceman’s Log Giving an old companion its voice back – by Dave Thompson 108 Circuit Notebook (1) High frequency adjustable LED strobe (2) Top octave generator using AVR micro (3) Formula 1 starting lights for slot cars (4) Six-decade resistor sorter (5) Phone call speech time warning Don’t look this bike light in the eye – it’s blinding! You can choose the way you mount it or use it. Page 100 114 Vintage Radio Kriesler Farm Radio, model 31-2 – by Assoc. Professor Graham Parslow Everything Else! 2 Editorial Viewpoint 4 Mailbag – Your Feedback siliconchip.com.au 98 Product Showcase 120 SILICON CHIP ONLINE SHOP 122 127 128 128 Ask SILICON CHIP Market Centre Advertising Index Notes and Errata Don’t miss the 2019 ElectroneX design and assembly expo in Melbourne this month. Exhibitor’s listing on Page 42. www.facebook.com/siliconchipmagazine SILICON SILIC CHIP www.siliconchip.com.au Publisher/Editor Nicholas Vinen Technical Editor John Clarke, B.E.(Elec.) Technical Staff Jim Rowe, B.A., B.Sc Bao Smith, B.Sc Tim Blythman, B.E., B.Sc Technical Contributor Duraid Madina, B.Sc, M.Sc, PhD Art Director & Production Manager Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Dave Thompson David Maddison B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Geoff Graham Associate Professor Graham Parslow Ian Batty Cartoonist Brendan Akhurst Founding Editor (retired) Leo Simpson, B.Bus., FAICD Silicon Chip is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 626 922 870. ABN 20 880 526 923. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Subscription rates (12 issues): $105.00 per year, post paid, in Australia. For overseas rates, see our website or email silicon<at>siliconchip.com.au Editorial office: Unit 1 (up ramp), 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 * Recommended & maximum price only. Printing and Distribution: Editorial Viewpoint 128 Pages: our largest issue ever! We have a huge issue this month with 128 pages. There are a few reasons for this. The first is to celebrate a successful twelve months as the new publisher of SILICON CHIP. My intention was for the transition to be seamless, keeping up the same high quality of content and service to our readers. From your many comments, I believe we’ve achieved that. I haven’t made any major changes to the magazine since Leo retired. It has been around for over thirty years and so must have been doing something right. As the old saying goes, “if it ain’t broke, don’t fix it”. We have made a few minor stylistic tweaks, just to freshen up the look and improve consistency here and there. But that’s it. I am happy with the quality and variety of our content (and I believe our readers are too). The only way that I thought we could improve the magazine was to run more of the same great content. And that’s what we’ve been doing. It is obviously more work to produce these larger issues, and it costs a bit more too. But I feel the result makes it worthwhile. I hope you have been enjoying the extra content. As I wrote in response to a letter in the Mailbag section last month, despite the extra expense involved, the magazine price has not changed, and I will keep it the same as long as possible. The intention is to give you, the reader, the best possible value for your money. Another main reason for the larger issue this month is that it coincides with this year’s ElectroneX exhibition in Melbourne and we have plenty of information on what you can expect to see if you attend. If you’re a Melbournite, or can spare the time to fly down for a day or two, it’s well worth attending. You will meet lots of interesting people, see some great technology and you will probably learn something too. I wish I could go, but publishing a magazine is time-consuming. We are represented by Glyn Smith, our Advertising Sales Manager, on stand D18. Call in and say hello! Next year, ElectroneX will be back in Sydney; hopefully, I will be there in person. The popular HRSA Vintage RadioFest is also on this month in Canberra, and we have an article on an interesting ‘farm radio’ in this issue. We also have some substantial Vintage Radio features coming up later this year. The final reason for having so many pages in this issue is the monster article on building a four degree-of-freedom gamer’s seat by Gianni Pallotti, starting on page 26. Normally we would run such an enormous article over two or even more months, but there’s a lot to this impressive design, and it would be difficult to split up. You need to be confident in your mechanical construction skills to take on that project, especially welding. But the result is a very impressive piece of equipment. Even if you don’t think you have the ability to build it, it’s still interesting to read about how he designed and made it. So when I saw what he’d done, I realised that we had to publish it. Dr David Maddison’s article on Cyber Espionage is quite fascinating, but I won’t go into any details about it here; you will have to read it and see! So I hope you enjoy this bumper issue. While we can’t promise to do this very often, I can promise to make SILICON CHIP the most interesting, best value for money electronics magazine not just here in Australia and New Zealand but anywhere in the world. Nicholas Vinen 24-26 Lilian Fowler Pl, Marrickville 2204 2 Silicon Chip Australia’s electronics magazine siliconchip.com.au siliconchip.com.au Australia’s electronics magazine September 2019  3 MAILBAG your feedback Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask Silicon Chip”, “Circuit Notebook” and “Serviceman”. GPS module compatibility problems I recently bought a pair of Arduinocompatible GPS receivers from AliExpress but found that none of the standard Arduino libraries could communicate with them. I tried AdafruitGPS, NeoGPS, TinyGPS and TinyGPS++. I decided to look for myself at the NMEA data being produced by these modules. I found that instead of the usual strings, starting with prefixes like “$GPGGA”, “$GPGSA”, “$GPRMC” and so on, I was seeing strings that started with “$GNGGA”, “$GNGSA”, “$GNRMC” and even some starting with “$GPGST” and “$GLGSV”. These different prefixes presumably explain why the usual libraries could not understand the NMEA data. But why are the prefixes on these modules different? I did some research and it seems like this could soon be a widespread problem. The explanation is in a document titled “NMEA Revealed”, which you can read at: https://gpsd.gitlab.io/gpsd/ NMEA.html#_talker_ids Here it explains that the “GP” prefix is the ‘talker ID’ for a GPS receiver. But “GN” is the talker ID for a mixed GPS and GLONASS receiver, while “GL” is GLONASS-specific. More receivers these days support GLONASS, the Russian system (this will be explained in some detail in the November issue – Editor). So you can expect more modules to use a GN talker ID, confusing many pieces of software. So really, these days, software needs to be designed to expect a different talker ID (or it can simply be ignored). Note that there are other talker IDs listed on that web page which modules may produce, so merely looking for “GP”, “GN” or “GL” may not be sufficient. I’ve since found that there is a version of the TinyGPS library which has been updated to support GLONASS and mixed receivers. See: https:// github.com/florind/TinyGPS Bera Somnath, Vindhyanagar, India. The moon landing was inspirational In October 1957, the world was shocked by the launch of the Russian Sputnik, the world’s first artificial satellite. It made quite an impression on me at 11 years old. The following year, the USA rushed to launch Explorer I, and over the next few years, satellite launches became more frequent. By 1962, there was sufficient ballast space on an American rocket to piggyback a small amateur radio transmitter known as OSCAR (Orbiting Satellite Carrying Amateur Radio). OSCAR orbited the world every 90 minutes or so, and broadcast HI in Morse Code (.... ..) on the 2m amateur band (144MHz). My father was a radio ham, and we followed OSCAR as it passed overhead, using Doppler shift to track its trajectory. At about this time, there was great excitement in the ham radio community about the possibility of communicating by bouncing signals off the moon. The first amateur to achieve this goal was an American, Sam Harris. We visited him at Rhododendron Swamp in Massachusetts USA and saw the 30-foot (9m) dish in his back yard. My father thought it a great lark. He started to build a similar dish back Visit us online at www.wiltronics.com.au 4 Silicon Chip Australia’s electronics magazine siliconchip.com.au Design, Develop, Manufacture with the latest Solutions! Showcasing new innovations in Electronics and Advanced Manufacturing Visit Australia’s largest Electronics Expo and see, test and compare the latest equipment, products and solutions for manufacture and systems development. Make New Connections • Over 90 companies with the latest ideas and innovations • New product, system & component technology releases at the show • Australia’s largest dedicated electronics industry event • New technologies to improve design and manufacturing performance • Talk to experts with local supply solutions • Attend FREE Seminars Knowledge is Power SMCBA CONFERENCE The Electronics Design and Manufacturing Conference delivers the latest critical information for design and assembly. Details at www.smcba.com.au In Association with Supporting Publication Organised by Free Registration online! www.electronex.com.au Melbourne Exhibition Centre 11-12 September 2019 Red/Green Panel Light Single Lamp 5 P/N SO58RGM $14.9 +gst • High Brightness LEDs • Wide Angle of Visibility • Combined Housing • Separate Circuits • Independent Earths • IP67 External Rated Making sure your switch panel project is; easily seen, highly visible, and stands out from the rest, is made easy with the SO58RGM. It comes standard with an in-built dual-coloured Red and Green function, all within a single compact unit. Perfect for internal or external control panels, vehicle dashboards, machinery, or any indicator, signal or warning application. Sales enquiries P: (03) 9466 7075 E: led<at>ledtech.com.au W: ledautolamps.com 6 Silicon Chip Quality ISO 9001 in Australia, but perhaps due to my mother’s objections, it was never completed. When we moved house, we left a partly constructed 30-foot dish behind. I wonder what the new owners thought. Inspired and taught by my father, I sat and passed the Theory and Regulations exams for the ham radio licence at the age of 15. You had to be 16 to get the licence. Imagine my surprise and delight when I woke up on July 21, 1962, to find my licence amongst my birthday presents! My father had been able to persuade the Postmaster General’s department (PMG) to issue it on the strict understanding that he would not give it to me until I turned 16. I doubt that this would be allowed nowadays. Fast forward to 1969, when I was a fourth-year medical student at Monash University. On July 21, we were in the middle of a Pathology practical class. The laboratory had closed-circuit TV monitors connected to the demonstrator’s microscope, but on that day they were switched over to TV, and the class watched Neil Armstrong set foot on the moon in real-time. The Americans celebrate the occasion on July 20, but Australia is a day ahead. The moon landing on July 21, 1969 was seven years to the day after I had obtained my amateur radio licence. I still find it hard to imagine that the moon landing was accomplished with so little computing power. At the time, the Monash medical course had an “elective” period of eight weeks where we could do just about whatever we liked. Most students spent this time doing clinical work, but I chose to spend it learning to program the PDP-8 computer. It was state-of-the-art with 4096 12bit words of core memory. It occupied a small room. Each bit was stored in a tiny doughnut-shaped magnet about half a millimetre in diameter, assembled by hand under a microscope, with two or three fine wires threaded through each doughnut. A typical memory card might have held a few hundred bits. The computers on the lunar landing craft were similar in construction and capacity. Very soon after the moon landing, core memories became obsolete, replaced by silicon chips containing millions of transistors, each of which Australia’s electronics magazine is now the size of about 1000 atoms. Magnetic core technology became just a memory! Today, the computer on my desk has a memory of eight gigabytes, where a byte is eight bits. However, over time, the old memory boards morphed from junk into collectables. My wife was puzzled when a parcel arrived from Russia. It was a memory board like those on the lunar module, and probably still contains stored data if we had a way to read it. James Goding, Emeritus Professor, Monash University (Vic). Response: the progress in technology since the late 60s certainly is amazing. The Apollo Guidance Computer ran at 2.048MHz with 4KB RAM and 36KB ROM. It consumed 55W and weighed 32kg. A PIC16F18877 has the same amount of RAM, more flash (56KB), consumes 1.2mW (yes, milliwatts!) at 4MHz, is under one gram and costs less than $2! Update on software-defined radios I recently came across an operating system package called Skywave. It reminded me of Jim Rowe’s series of articles on SDR in October and November 2013 (SiDRADIO; siliconchip. com.au/Series/130) and November 2017 (Banggood SDR kit; siliconchip. com.au/Article/10879). Skywave is a free, open-source Linux-based operating system that contains probably every freely available SDR software package. You can download it from skywavelinux.com or buy a USB drive with the OS already installed and ready to boot from osdisc.com It can be dual booted with Windows or used to bring an old loved, but no longer viable, laptop back to life and made useful again. I tested it out by invoking “Ham Radio” in the Applications Menu, then Web SDR and Open Web RX Servers. This took me to a page with Online SDR Servers where I clicked on University of Twente Netherlands (Wideband ADC). This took me to the website http:// websdr.ewi.utwente.nl:8901/ which describes a “homebuilt SDR Board” using a Spartan XC3S500E field-programmable gate array (FPGA). For anyone interested in SDRs this is an awesome website outlining the development and assembly of this SDR. siliconchip.com.au Dev Tools Workbench 205X275.pdf 1 29/7/2019 2:28 PM C M Y CM MY CY CMY K siliconchip.com.au Australia’s electronics magazine September 2019  7 The LogBox 3G is an IoT device with integrated data logger and 3G / 2G connectivity. Free access to Novus Cloud for storage and access to data SKU: NOD-011 Price: $699.95 ea + GST It was the first ‘WebSDR’ ever, going live in 2008. You might want to consider basing an article on this design. By the way, the $30 SDR kit from Banggood Jim wrote about back in 2017 can now be purchased fully-assembled for $35, including postage. I’d also like to mention that your article on Radiation and Electronics in the July 2019 issue was very revealing. Jacob Westerhoff, Seaford Rise, SA. Temperature and Humidity Sensor Dad enjoyed reading Silicon Chip Helping to put you in Control LogBox Connect 3G Ideal for building automation applications the RHT-WM is an accurate wall mount temperature and humidity sensor with 4 to 20 mA outputs and is loop powered. Adjustment of output ranges can be made with TxConfig PC interface. SKU: RHT-003 Price: $209.00 ea + GST DC Earth Fault Relay A Din rail mounted current sensing relay dedicated for DC earth fault monitoring, such as insulation deterioration on a DC system. The unit is supplied complete with a dedicated DC Earth Fault CT. SKU: NTR-290 Price: $245.00 ea + GST Split core current transducer Split core hall effect AC current transducer presents a 4 to 20 mA DC signal representing the AC current flowing through a primary conductor. 0 to 100 A primary AC current range. SKU: WES-076 Price: $109.00 ea + GST Programmable Logic Relay The TECO SG2 Series PLR V.3 is 24VDC Powered, has 6 DC Inputs, 2 Analog Inputs, 4 Relay Outputs, Keypad / Display, Expandable (Max. 34) I/O. SKU: TEC-005 Price: $149.95 ea + GST 3 Digit Large Display Large three digit universal process indicator accepts 4 to 20mA signal with configurable engineering units. 10cm High digits. 24V DC Powered. SKU: DBI-020 Price: $449.00 ea + GST Raw & Waste Water Level Sensor 2 wire 4 to 20 mA liquid level sensor 0-3m. Suitable for raw and waste water. Supplied with 10m cable. SKU: IBP-104 Price: $369.00 ea +GST For Wholesale prices Contact Ocean Controls Ph: (03) 9708 2390 oceancontrols.com.au Prices are subjected to change without notice. 8 Silicon Chip My father, David Costello, was a regular Silicon Chip reader. Sadly, he passed away recently. Electronics fascinated my dad from an early age, and your marvellous magazine gave him many hours of enjoyable reading over a very long time. Just as importantly, it provided a great many more hours figuring out the next project, visiting Jaycar for supplies, and then sitting with a soldering iron, drill or screwdriver in hand till it was finished. Thank you for your significant contribution to my dad’s enjoyment in life and keep up the excellent work. Maree Costello, Rowville, Vic. Apollo 11 TV broadcasts Over the week around the 50th anniversary of the moon landing, there have been many documentaries of varying quality, particularly regarding Australia. I happened to be at ABC Sydney, where I watched the landing in colour, six years before Australia commenced colour TV broadcasting. The USA had NTSC colour TV at the time. I found the following article on the topic of the Apollo 11 TV broadcasts, which I believe is authoritative: www. hq.nasa.gov/alsj/ApolloTV-Acrobat5. pdf But based on my television engineering training at the ABC, I can comment further. The TV camera used on the lunar lander produced 262.5 image lines with another 57 black lines. They were scanned in progressive order, not interlaced. No domestic TVs could display these images, so a slow-scan converter was required to convert the image to the USA’s NTSC system, which has 480 interlaced image lines and 45 black lines, yielding 262.5 lines per field. The lunar camera produced 10 frames/second, but NTSC has 59.94 fields/second. So the images were Australia’s electronics magazine stored and each camera frame was shown six times with each alternate field delayed by half a line. Unfortunately, there was no way to synchronise the lines of the USA TV system back to the camera on the moon. As a result, the lunar images were shown on a long-persistence cathode ray tube, with a camera pointed at it. The long persistence phosphor on the CRT was used to increase the brightness and also to smooth the jerky motion caused by the very low 10 frames/second scan rate. The picture quality was reduced because of the camera pointed at a picture tube; it smeared movement and the grey-scale was distorted. The Field Sequential Colour camera contained a rotating red, green and blue filter wheel. ABC Sydney had a Slow Scan Converter, so a technician connected the outputs of the red, green and blue stores to the only colour monitor on the station. So, we were able to watch the feed in colour. The colour was good except when there was motion and the red, green and blue images would separate. Apparently, the original recordings were destroyed, so it is not possible to recover the colour images. The output of the Slow Scan Converter was unsuitable for Australian TV, so a second scan converter containing a CRT/camera was used to convert the signal to our standard of 575 interlaced image lines, with 50 black lines at 25 frames/second. That made the picture quality even worse. The moon landing video was distributed to the world from Honeysuckle Creek, which is in the Tidbinbilla Valley, ACT. The CSIRO’s Parkes NSW radio telescope was capable of reception too, and Carnarvon, WA was used for telemetry. Alan Hughes, Hamersley WA. Jaycar’s Maker hub is near Sydney TAFE The August article on Jaycar’s Maker Hub neglected to mention Sydney (Ultimo) TAFE, located behind UTS. Ultimo TAFE offers a wide range of electro-technology courses covering electronics, security and electrical work from Certificate II, III, IV, Diploma and Advanced Diploma Courses. When I first attended Ultimo TAFE in the mid-1980s, I remember walking past an electronics store every day (possibly called Radio Parts), in what is now siliconchip.com.au Making premium hearing technology easier for you to access and afford. Get your hands on award-winning hearing technology — in a few simple steps. 2. Buy hearing aids online or in person 1. Understand your hearing Head to blameysaunders.com.au to take our free online hearing test. It’s clinically validated, gives you accurate insights, and we can use your results to set up hearing aids for you. Place an order on our website or over the phone to have your devices express shipped— ready to wear out of the box. Or, visit us in one of our pop-up or permanent-location clinics. 3. Personalise your settings 4. Choose your level of support Our award-winning IHearYou® app lets you personalise your settings yourself, so what you hear is always just right. No repeat visits to a clinic required. Our friendly experts are here for you every step of the way. We can even help you program your hearing aids, over the internet. Visit blameysaunders.com.au to help yourself to better hearing today! Call 1300 443 279 Email info<at>blameysaunders.com.au siliconchip.com.au Australia’s electronics magazine September 2019  9 part of McDonald’s Broadway. Hopefully, the success of Jaycar’s second Sydney city shop will encourage other specialist electronics stores to open. Geoffrey Lee, Ultimo, NSW. Comment: the store was called Radio Despatch Service (RDS); managed by Norm Edge and Geoff Wood. Getting out of electronic manufacturing I am a retired electronic engineer. I spent six years in the RAAF as an air radio/radar tech. I also worked as a supervising radio tech on Macquarie Island. On my return in 1964, I applied for a position with Fairchild Semiconductor. The company was set up in an office block in South Yarra, Victoria. After a couple of years, they built a factory in the eastern suburbs at Kilsyth. I worked there for a few years and was then head-hunted by Anodeon Semiconductor as a senior product engineer. I eventually left Anodeon to start my own manufacturing company and obtained several contracts with government departments. We manufactured PCBs and did general electronics manufacturing of both of our products and also for those departments. We manufactured many PCBs for companies such as AWA, HMV and Radio Corp. Some of our main products were solar heating controllers for swimming pools and spas. Some years later, I sold the business but continued working as chief engineer. I produced several new designs for pool solar controllers and heat-pump controllers before the owner decided I was too expensive and replaced me with a young engineer. Consequently, I set up another small business working from home, which continued up until last year. My problem now is that I have a considerable stock of components, including blank PCBs and fully assembled circuit boards that I would like to dispose of. I cannot bring myself to throw them away, and I would like to at least get something for the assembled PCBs. All the controllers I have ever designed have been inspected and approved to AS/NZS 3136 by Electrical Safety Victoria and full documentation is available. I can supply all manufacturing documentation, software, circuit diagrams, enclosure details etc. The PCBs were designed using Protel and the PCB files can be supplied. 10 Silicon Chip Australia’s electronics magazine Most components were purchased through Altronics and the enclosures came from NAW Controls. I am wondering if any of your readers would be interested in what I have to offer. Don Myles, Chirnside Park, Vic. Comment: if any readers are interested in contacting Don to discuss acquiring his designs and hardware, email us and we’ll forward it on to him. Another RCA AR-812 radio restoration I just got my copy of the August issue to find an article on restoring an RCA AR-812 radio (siliconchip.com. au/Article/11782). Just the previous day, I’d watched a YouTube video from Glasslinger on the very same radio. Quite a coincidence! The video can be found at: https://youtu.be/UnzVbkcQWCE Wenlock Burton (VK3YWB), via email. Contributor received a design award I have just heard the most amazing story about Ian Robertson of Warriewood, author of the Analog Audio/Video Modulator (March 2018; siliconchip.com.au/Article/11007). Editor’s note: not to be confused with Ian Robertson of Engadine who is a prolific Circuit Notebook contributor. Ian has been awarded a 2019 Good Design Award for his InstallMate – see https://good-design.org/gooddesign-index/ Australia’s annual Good Design Awards program is one of the oldest and most prestigious international design awards in the world, promoting excellence in design and innovation since 1958. It is recognised by the World Design Organization (WDO) as Australia’s peak international design endorsement program. Ian is 70 years old and employed by CommBox. Ian and his late wife Jenny started CommBox in the 1970s. Upon her passing, he handed the company over to his daughter, Therese Halls, who is the current owner of CommBox. This is a great story of achievement in the twilight of your career and of family companies surviving. So I thought it might interest you and your readers. Oliver Goodman, via email. Strange problem with Class-D amplifier After reading the article on the “El Cheapo” Class-D amplifier modules siliconchip.com.au by Allan Linton-Smith (May 2019; siliconchip.com.au/Article/11614), I purchased an XD172700 Class-D amplifier board. I then set about modifying the output inductors as described in that article, to change their values to the correct 10µH. I did this by removing many of the windings and adjusting the remaining windings to be evenly spaced around the toroidal cores. The odd thing is that after I did this, at high volume, both right-hand coils (looking from the back of the board) heated up badly to the point of going black and smelling bad. I switched it off quickly when I noticed that! I have carefully checked the continuity of the board tracks to make sure I didn’t short them to ground when I re-soldered the modified coils back in place, and it was all good. The lefthand coils of each output channel did not heat up at all. After this, I decided to make entirely new air-cored coils, as the article said they should ideally be air-cored. I used an online calculator (http:// electronbunker.ca/eb/InductanceCalcML.html) and based on the available physical space, decided to make the coils 19mm in diameter with a 7mm inner diameter. I used 0.95mm diameter wire. This requires six rows of six turns each, which when hand-wound on a custom former, fits exactly in that space. The online calculator gave a value of 11.38µH, and I was delighted to find my finished coils measured 11.1µH, 11.2µH, 11.3µH and 11.4µH. With a 24V DC supply and the volume set loud enough for the neighbours to enjoy, after several minutes, I could not feel any warmth in the coils at all. A considerable amount of effort went into making the former and coils, and this may not be for everyone, but I want the amplifier for the long term. Geoff Stone, Eaton, WA. Self-contained TDR wanted Congratulations on the continuing excellence in the projects presented by Silicon Chip magazine. I was browsing through some back issues of Silicon Chip and came across the Micromite-based DDS IF Align- ment project from September 2017 (siliconchip.com.au/Article/10799), which plotted the intermediate frequency response of a radio receiver on the Micromite LCD BackPack touchscreen. This gave me the idea of a similar device to detect cable faults, like Jim Rowe’s Time Domain Reflectometry dongle design from the December 2014 issue (siliconchip.com.au/Article/8121), except without needing an external scope. I feel the Micromite and touchscreen combination could be configured to provide such a facility. This would also be much more convenient to use as you wouldn’t need two separate units, including an expensive DSO which you may need to lug around with you in the field. William Spedding, Lake Cathie, NSW. Response: that is an excellent idea, although it isn’t as easy as it sounds. To see the signal reflection and locate a cable fault accurately, you need to be able to measure the timing of the ‘echo’ to a resolution of around 1ns. That means you need an effective S E e M lec e us St elb tro a an ou ne t d A rn x 15 e sampling rate of around 1GSa/second; far beyond what even a very fast micro can achieve with its internal analogto-digital converter (ADC). Don’t expect to see a project just yet, but we are formulating some ideas that may allow us to achieve the required performance with a Micromite. Support for idea of RPi-based media player I was interested to read Raff Lerro’s letter in the March 2019 issue, suggesting a project based around a Raspberry Pi for playing various media types, supporting improved power on/off, a remote control etc. The author points to his use of MPEG4 for capturing DVDs for playback, and FLAC for CD audio. His choice of a lossless format here is interesting, rather than high bit rate MP3... Personally, while I haven’t given much thought to the software side (Raff suggests Kodi, but there are other options like Plex or Emby), I am interested in the notion of combining the digital processing capability of Pi with a high-quality DAC, possibly your CLASSiC DAC (FebruaryMay 2013; siliconchip.com.au/Series/63). I’d like to suggest modularising a high-quality DAC, which can then be used in several contexts (such as the stand-alone device already described). That could then be used as part of a Pi-based media player, as suggested by Raff. Of course, the “all-singing, all-dancing” player might need its own touchscreen, plus suitable outputs for both audio and video to feed external amplifiers, televisions etc. Geoff Best, Wamboin, NSW. Response: it’s an interesting idea but would take a lot of development work. Off-the-shelf high-quality DAC solutions are already available for the Raspberry Pi, but we haven’t tried them. While MP3 may be OK for listening in the car or with earbuds when out and about, its sound quality isn’t good enough for home hifi systems. FLAC is the way to go if you have a good amp and speakers. Comments on August issue Concerning your August Editorial Viewpoint, I applaud the move to make the Micromite one of your standard platforms. Obviously, not everyone will want to use a Micromite, but I imagine that the Arduino and the Raspberry Pi platforms will not be ignored. However, there is one thing that puzzles me, and that is the lack of projects and articles that use micros of other manufacturers. Why is that? Regarding the letter from John Evans in the Mailbag section (page 13), I have to agree with him. I was hoping to get FTTN with an upgraded phone line, but instead, I have been connected to the old Foxtel cable (HFC). The university got rid of the multidrop coax years ago for various reasons, including congestion. Now my area has it, and I fear we will suffer the same congestion problems. I really hope that Telstra recommended to the clowns who are building the NBN that the first priority should be the updating of the inter-city and the exchanges’ internet links. The Quantum-Dot Cellular Automata article in the August issue (siliconchip.com.au/Article/11774) was news to me. I am familiar with cellular automata and A-Life, but this took me by surprise. I wonder if anything will come of it. Only recently, Dr Maddison presented an article concerning the effects of radiation on microelectronics and 14 Silicon Chip particularly very small scale devices (siliconchip.com.au/ Article/11697), and here there is a hope of creating devices utilising single electrons. I think the researchers had better include significant error correction mechanisms before they proceed further. In the Mailbag section of the June 2019 edition, Kelvin Jones suggested reticulated low voltage in homes and Nicholas Vinen as part of his reply stated that the performance of battery power vacuum cleaners was inferior to mains powered appliances. I think the correct description of the “vacuum” of the battery appliances is a gentle breeze. I bought a couple of hand-held battery-powered machines, one for myself and one for a present. I realised very quickly that as supplied, they are almost useless. However, the purchase of a long-hair paintbrush changed that. When cleaning dust from circuit boards, the brush frees the dust, and there is sufficient “suction” for the battery-powered machine to remove it. It works very well, and I hope it is of use to others. I got this idea from the Super Hero robotic floor cleaner. It has a rotating cylinder brush and two contra-rotating brushes with one on each side of the front of the machine. Effectively, it is a sweeping machine with a fan that directs the dust and dirt to a collection area and on a plain wooden floor and tiles; it works well. I think it is a bit harsh to condemn the battery-powered machines based on their “suction” ability only. I know that my mains-powered machine cannot remove some types of dirt by suction alone. However, it has a rotating brush head, and that makes the difference. George Ramsay, Holland Park, Qld. Nicholas responds: regarding the micros used in our projects, there are dozens of different kinds available and many are excellent. But it’s impractical for us to have the required programming hardware and software to suit them all, and we think the same is true of our readers. We try to stick mainly to PICs so that our readers only need a PICkit or similar to build our projects. Also, it would take a lot of extra time to learn the quirks of each different platform, its compilers, libraries etc. It’s much easier to stick to the one ‘ecosystem’. There are hundreds of different PICs, suitable for just about any application, and the prices are quite good too. So if we have to pick one primary micro family, Microchip’s products (which now include AVRs) are a good choice. I agree that noise and interference are likely to be the biggest challenge facing Quantum-Dot Cellular Automata techology at useful scales. Time will tell whether it can be made to work in the real world or not. Our cordless vacuum works quite well on some surfaces as it has a rotating brush built into the head. But you can’t use that brush on all surfaces, and then it leaves dirt behind. That’s true even on the “max” power setting, which drains the battery in about five minutes! It’s especially bad where there are nooks and crannies; a mains-powered vacuum is usually powerful enough to suck particles across the gap between the nozzle and the dirty surface. But the battery-powered vacuum can’t. Ultimately, the battery-powered vacuum is too convenient to ignore, but that can’t make up for the lack of power in all situations. Sometimes I still have to drag out the extension cord... Australia’s electronics magazine siliconchip.com.au Shocking tales of quality control failure Nicholas Vinen’s Editorial Viewpoint in the February issue regarding dodgy and counterfeit products stirred up some bad memories of my experiences in quality control. I think the label “quality control” is often misunderstood and is used as a panacea to make us feel safe when we buy a product. It doesn’t always ensure quality products, however. My first bad experience occurred when I was a quality control supervisor with a large, well-known international company. One of our products was an oral medicinal tablet which was sealed in foil. It was well known that the tablets had a shelf life of 12 months, after which time the ingress of moisture through the foil changed the active ingredient to an inert one. There was consternation on the production floor one day when a special line was set up to process several pallets of this product which were out of date. The warehouse had not rotated the stock, and these pallets had remained unsold, until it was realised that they could not be sold because they were past their “use by date”. The production line was instructed to remove the foils from their boxes and insert them into boxes with that day’s date. I was unhappy with this situation and told my boss that this was blatantly wrong. I was told that we had to do this to keep making a profit. I left that company soon after as it was weighing on my conscience. My second traumatic experience as a quality audit supervisor was with a company which manufactured rolls of laminated sheeting which was glued together using two-part epoxy glue. One night, someone forgot to add the hardener to the adhesive tank, and as the hours rolled by, kilometres of laminate were produced with the adhesive/ hardener ratio progressively going beyond specification. Eventually, the quality control department notified production of the weak bond strength from the sample taken at the end of each roll, but it was only when the bonding was well out of tolerance that the process was stopped and the problem rectified. To cut a long story short, the company owner came to the factory late one night and ordered that these faulty rolls be sent out; the good to be blended in with the bad. The owner was gambling that the customers’ quality control would find the rejects and that they would be within the allowable limit which was in our supply contract. My most recent quality experience disaster was at a company which manufactured industrial benchtop digital weighing scales. It was a small company with an excellent overseas reputation for good product quality. We had an excellent testing process, which included “soak testing” every unit under power at 40°C for 14 days. But our smugness was shattered one day when one of our units failed in the USA. This was followed shortly after by another failure, then another. We eventually found out that the large capacitors in the power supply were leaking their electrolyte. We purchased our capacitors from a German company which produced high-quality components, and we notified them of the failures, although the damage to our reputation had already been done. It seems that the rubber seal at the end of the capacitors had failed due to premature deterioration. The rubber sheeting for the seals was supplied by a manufacturer in Japan siliconchip.com.au Who the #?!&*% is… • Operating since 1980. • Contract manufacturer, UL compliant, with engineering capability. • Your products may change but your contract manufacturer doesn’t have to. How to find a reliable contractor! Team up with us for the long haul. • We create a quality plan for every product we make for you. • Contact us for a free quote. www.elfelectronics.com.au 1300 367 353 lorenzo<at>elfelectronics.com.au who produced a high-quality product. But the rubber had been contaminated in some far, far away rubber plantation. It was difficult for us to foresee this disaster. I remember another small company which manufactured domestic fans some years ago. When these fans came off the production line, they were tested for correct operation. When they failed the tests, some of the units were not repaired; they were merely sold to customers in remote areas, knowing that these customers would find it difficult to return the item for a refund! The problem of the defects was solved; the customers sent the units to landfill. If rejected products cannot be recycled, they may not be disposed of properly. It costs money to dispose of rejects. Even if they are thrown away, sometimes people dig them up and then sell them! Then there is human error; reject stickers can fall off. Employees become dissatisfied and sabotage their production work. We all have “I don’t care days”. It would be great if perfect units could be produced every time, but this does not happen. It would be excellent if every component and circuit could be placed on a ‘bed of nails’ to be fully tested before sending it out, but for reasons of cost and time, this does not happen. Tony Farrell, Kingscliff, NSW. SC Australia’s electronics magazine September 2019  15 A BRIEF HISTORY OF CYBER ESPIONAGE AND CYBER WEAPONS Part 1 – espionage methods over the years – by Dr David Maddison S Part 1: pre-existing electronic hardware vulnerabilities and creating vulnerabilities pying on one’s enemies (or even one’s friends!) or sabotaging infrastructure is one of humanity’s oldest activities, but electronics vastly expanded the possible ways of doing so. In this article, we’ll describe some fascinating espionage methods that can be (and have been) used to take advantage of hidden flaws in everyday equipment, allowing spies to get their hands on all sorts of secret information. Naturally, many such techniques are secret, but there are still many that have been described in the open literature, that we explain below. The variety of technologies and methods of concealment of electronic espionage is immense, so we can only survey a portion of those, and give the most interesting examples. The number of ways people have devised to spy on each other is seemingly only limited by the imagination. We’ve come up with so many interesting electronic espionage techniques that this article will concentrate on those which exploit vulnerabilities in electronics and hardware, and techniques for creating vulnerabilities which can then be exploited later. Next month, we’ll have a follow-up article covering other electronic spying techniques, which we don’t have room for in this article. Unintentional “leakage” Many of the techniques described below can be classified as a “side-channel attack”. This involves the unintentional leakage of information from a system, such as RF or optical emanations from the 16 Silicon Chip device, which are an unwanted side effect of its regular operation. We present these in chronological order, to give an idea of the history of such exploits, which goes back further than you might imagine. We’ll start with pre-existing hardware vulnerabilities (side channel attacks). TEMPEST and teleprinters During the second world war, it was noticed that the plain text from encrypted teleprinter communications could be recovered some distance away. This is because of the significant EMI generated when the relays within the units switched on and off. Fig.1 shows one of the affected units, a Bell 131-B2. To work around this problem, commanders were instructed to maintain a secure zone for 33m around the encryption device. There were technical fixes put in place to reduce the EMI leakage, such as adding shielding, power supply filtering (to prevent signals travelling back along supply lines) and the use of lower-power relays which generated lower amplitude spikes when switching. But these efforts were not entirely successful and only reduced the distance over which information could be gathered, rather than eliminating the problem altogether. Another problem was that while reduced power operation reduced leakage, it also limited how far apart the connected equipment could be, or how many teleprinters could be driven at once. The problem wasn’t just limited to teleprinters, either. Signals from some electronic typewriters in use after WWII, Australia’s electronics magazine siliconchip.com.au Fig.2: the commercially-available Orion 2.4 HX Non-Linear Junction Detector. Fig.1(left) : a Bell 131B2 mixer, which was used to encrypt or decrypt teleprinter signals using relay logic. Its electronic emissions could be picked up some distance away. including in embassies and other secure locations, could be picked up and decoded from as far away as 1km! Due to the scope of this problem, in the early 1960s, the USA produced a set of guidelines under the codename TEMPEST, intended to prevent enemies from gaining access to classified information due to these types of emissions. In some locations, such as the US embassy in Moscow, equipment was installed in Faraday cages to significantly reduce electronic emissions. Apparently, staff did not like working inside them and referred to them as “meat lockers”. For more information, see the Wikipedia article on TEMPEST at: siliconchip.com.au/link/aaqp Interestingly, many of the TEMPEST guidelines are still applicable today, and some of the attacks described below would not be possible if the vulnerable systems complied with those standards. Non-linear junction detectors A non-linear junction detector is a device which was once used to find bugs (Fig.2). These work even if the bug is powered off. It uses the principle that a non-linear junction such as a p-n junction, as found in a transistor or diode, gives a characteristic response when illuminated with radio-frequency energy. This allows out-of-place electronic devices to be detected, eg, those hidden in walls or decorations. Such detectors can be easily defeated, however, by a loadmatching device called an isolator, and the US CIA has done so with their listening devices since 1968. Black Crow In 1970, during the Vietnam war, a phased-array antenna system called Black Crow (AN/ASD-5) was fitted to C-130 Spectre gunships (cargo aircraft modified for ground attack duties). This could detect the electromagnetic emissions of vehicle ignition systems up to 16km away (see Figs.3 & 4). This system was initially designed for picking up submerged submarines, as a form of Magnetic Anomaly Detector, but some bright spark (no pun intended) realised that it could also be used by aircraft to pick up the emissions Fig.3 (left): a Vietnam War-era AC-130A “Spectre” gunship, one of the types outfitted with the Black Crow system. Note the side-facing radome near the front of the aircraft, along with the barrels of multiple cannons aimed in the same direction. Fig.4 (right): the sensor operator station in a modern AC-130 aircraft, using cameras, radars and other equipment to locate enemy targets. siliconchip.com.au Australia’s electronics magazine September 2019  17 Fig.5: an image recovered from the LCD screen of a 440CDX laptop 10m away, through three plasterboard walls (M.G. Kuhn, University of Cambridge Computer Laboratory, 2004). The image is not perfect but is certainly readable. from the ignition systems of enemy trucks travelling along the Ho Chi Minh trail, much of which was obscured by jungle. Once detected by the system, there was no need to spot the trucks visually for engagement; the output of the Black Crow system was able to control the gunship targeting computers directly, to aim cannons at vehicles even though they could not be seen through the dense jungle canopy. It could also pick up radio transmitters on the ground, such as those used by Forward Air Controllers, who relay targeting information to aircraft. CRT and LCD monitors (RF emissions) While CRT monitors are rarely used today, in 1985, Dutch researcher Wim van Eck demonstrated in open literature that simple and cheap equipment could be used to reproduce images from remote computer monitors. This was done by picking up their RF emissions, an activity then thought to be restricted to major government espionage operations. The technique came to be known as “Van Eck phreaking”. It can also be applied to LCD monitors, including those used in laptop computers – see Fig.5. You can read the original paper at: siliconchip.com.au/link/aaqq Today, Van Eck phreaking can be done with cheap software-defined radios (SDRs) with appropriate software, such as Martin Marinov’s TempestSDR – see Fig.6. If you want to try this, we suggest you test it on your own computers, as using such software without the target’s permission or knowledge is likely to be illegal and could get you in trouble. For more information on TempestSDR, see the video titled “TempestSDR - Remotely Eavesdropping on Monitors via Unintentionally Radiated RF” at: siliconchip.com.au/link/aaqr TV licence vans (UK) Some regard them as a hoax, but the information above about Van Eck Phreaking, and the fact that radar detector detectors exist (note, that is not a misprint!), suggests that it may be possible for vans to drive around and detect nearby operating CRT television sets. However, the number of prosecutions achieved for op18 Silicon Chip Fig.6: a screen grab of the TempestSDR software receiving a checkerboard pattern from a remote computer (background). In the foreground window, part of the received image is shown, along with some signal spectra. erating a TV without a license in the UK was quite small. Blinking lights In 2002, it was discovered by researchers J. Loughry and David Umphress that the LED status lights of modems and other data communications equipment could reveal the data being carried by the device. No installation of malware on connected computers was required to take advantage of this, and the authors suggested design changes to prevent such data leakage. This was found to even be possible with lights observed from afar with a telescope. Decoding diffuse reflections from monitors Also in 2002, M. Kuhn at the University of Cambridge demonstrated the reconstruction of an image from a CRT monitor screen, using only the diffuse reflection from objects such as a wall or furniture. This was shown to be possible even through curtains, blinds or frosted glass. It was determined that the contents of a CRT screen, even with small fonts, could be established by the use of a 300mm astronomical telescope from 60m away, observing the CRT reflection from an object. Having acquired the image data, mathematical image processing was used to recover the image from the screen – see Figs.7 & 8. This technique is known as “optical time-domain eavesdropping”. It takes advantage of the fact that although a CRT screen appears to have a steady image, only a tiny portion of the screen is actually illuminated at any given time, and the ‘persistence of vision’ of our eyes causes the illusion of an image covering the whole screen. So a simple light sensor can be used to pick up the changes in brightness off diffuse objects on a short time scale. It is then possible to determine the horizontal and vertical blanking intervals based on breaks in that illumination, to simulate the movement of the beam across the CRT screen, then apply the same brightness variations to reconstruct that image without needing to observe it. While modern LCD and OLED screens are updated in a Australia’s electronics magazine siliconchip.com.au Fig.7: a test image, displayed on a monitor which was not directly observable (eg, facing a wall, with the observer able to see the wall but not the monitor). Fig.8: the image recovered after applying mathematical techniques to the diffuse reflection from the wall. Again, it’s not perfect but is largely legible. similar scanning manner to a CRT, because the image on the screen is steady, this technique is unlikely to work. network to recognise keypresses on a keyboard. The resulting accuracy was as good as one incorrect guess per 40 keystrokes, and the method worked at distances of up to 15m. Cloning key fobs In 2008, it was demonstrated that the KeeLoq proprietary code-hopping cipher used in many garage and car door opening systems could be compromised. The cryptographic keys used by a particular manufacturer could be recovered by measuring the power consumption of a device (in possession) such as a key fob during the encryption process. Once the cipher for a specific manufacturer is recovered, it is then possible to intercept two transmissions from a target key fob from as far away as 100m, and the device can be cloned. Furthermore, it is then possible to lock out the legitimate user of the cloned device. Some keyfobs, including older ones used for opening cars and garage doors, can be cloned without resorting to such clever tactics. Those which do not use rolling codes, just a basic handshake, are subject to a simple ‘replay attack’. In this case, recording and replaying their RF emissions may be enough to gain access. This has been demonstrated using an SDR (software-defined radio). Breaking systems that use a weak rolling code requires a bit more refinement (but not much); with many such systems, recording the RF associated with two subsequent access attempts (or possibly even just one) can be enough to establish the code being used and allow the attacker to later produce the next code in the sequence, opening the door. The NSA ANT Catalog The NSA ANT Catalog is like a mail-order catalog of electronic espionage equipment available from the US National Security Agency. ANT is their Advanced Network Technology division. It was produced in 2008 and reflects Leaking acoustic and electromagnetic radiation from keyboards Computer keyboards can leak RF radiation which can be used to decode what is being typed on them. In 2008, researchers Vuagnoux and Pasini (and many before) demonstrated the successful reading of multiple keyboard types including PS/2, USB, wireless and laptop boards, with 95% recovery of keystrokes up to 20m away, and even through walls. Acoustic emanations from keyboards can also be used to decode what is being typed, due to imperceptible differences in the sounds of individual keystrokes. In 2004, researchers Asonov and Agrawal used this method to train a neural siliconchip.com.au Fig.9: just one of the dozens of pages from the NSA ANT Catalog, which lists the electronic espionage tools available to friendly government agencies. This page shows a tiny device which can be hidden in a computer monitor cable, allowing the screen contents to be remotely read when illuminated by a radar. Australia’s electronics magazine September 2019  19 Fig.10: researchers demonstrated the ability to read text off a smartphone screen from reflections off a variety of objects, including the user’s eyeballs! items available to the NSA, US citizens and the Five Eyes intelligence alliance (which includes Australia). A sample page is shown in Fig.9. It was released to the public by the German magazine Der Spiegel from an unknown source in 2013. A copy of the catalog can be seen here: siliconchip.com.au/link/aaqs Most of the devices involve exploits against networked computer systems or mobile phones, and many are targeted toward the equipment of specific manufacturers. Highlights from the catalog include: • COTTONMOUTH, a USB “hardware implant” that provides a wireless bridge into a target network with the ability to load software on target PCs • NIGHTSTAND, which exploits weaknesses of the wireless 802.11 protocol to access wireless networks from as far away as 13km Remote observation of vibrating objects to recover audio This technique, developed by researchers at the Massachusetts Institute of Technology (MIT), is known as “passive recovery of sound from video” or the “visual microphone”. It involves visual observation of an object in a room under surveillance, and recovery of audio (including speech) from vibrations of that object, caused by sound in the room (see Fig.11). Objects that this technique has shown to be successfully used with include a chip packet, aluminium foil, the surface of a container of water and plant leaves. These observations were made with a high-speed video camera at 2000-6000 frames per second (FPS), but effective • SURLYSPAWN, a device to provide a signal return encoded with information from low data rate devices such as keyboards when illuminated with radar • GOPHERSET, a software implant for GSM phone SIM cards which sends phone book, SMS and call logs from a target phone to a user-defined phone number via SMS Reflections from eyeballs, sunglasses etc In 2013, researchers Yi Xu et al demonstrated how text on a smartphone screen could be read by observing screen reflections on objects such as 1) sunglasses and a toaster, 2) via reflection from eyeball, 3) reflection from sunglasses, 4) viewing from a long distance, plus they could decode typed words using finger motion analysis – see Fig.10. You can see some videos on this subject, and original publication, at: siliconchip.com.au/link/aaqt 20 Silicon Chip Fig.11: “the visual microphone”; recovery of audio from video observation of a chip packet. In this case, the audio being recovered is a pure tone rendition of “Mary had a Little Lamb”. Australia’s electronics magazine siliconchip.com.au results were also obtained with a consumer-grade digital SLR (DSLR) camera operating at 60 FPS. Even though the vibrations are not visible to the naked eye, sub-pixel variations representing soundwaves can be extracted with appropriate data processing. Observations were performed at a distance of up to four metres, but longer distances are thought to be possible with appropriate optics. For more information, see the video titled “The Visual Microphone: Passive Recovery of Sound from Video” at: siliconchip.com.au/link/aaqu Remote mobile phone microphone activation In surveillance terminology, a “roving bug” or “hot mic” (microphone) refers to the microphone in a mobile phone which has been activated as a listening device, whether a phone call is in progress or not, or even if the phone appears to be turned off. This technique is employed by intelligence agencies using a variety of methods, including the use of a suite of smartphone hacking tools known as “Smurf Suite” for Android and iPhone devices. This was developed by the US NSA, as revealed by The Guardian newspaper in January 2014. It’s possible to listen to the microphone on a phone that is apparently turned off because some phones still have some circuitry running even when off, and they can only be truly deactivated by removing the battery. See the video titled “Edward Snowden: ‘Smartphones can be taken over’ - BBC News” at: siliconchip.com.au/link/aaqv Encryption key recovery using PITA In 2015, researchers from the Laboratory for Experimental Information Security at Tel Aviv University in Israel made a demonstration at a cryptographic conference, to show the vulnerability of computer systems to RF sniffing. They called their invention PITA, which stands for Portable Instrument for Trace Acquisition. They non-invasively recovered cryptographic keys from a laptop 50cm away in only a few seconds, by picking up its RF emissions with cheap and readily-available equipment, including an SDR (software defined radio) dongle – see Fig.12. They alerted GnuPG, the open source organisation that supplies the widely used encryption software called PGP (“pretty good privacy”; not “great privacy”, apparently), which was the subject of the demonstrated attack. This software was subsequently modified to prevent this attack, although other cryptographic systems could be vulnerable to similar schemes. For more details on PITA, see: siliconchip.com.au/link/ aaqw Spying on vehicle occupants Many modern cars have computer systems that connect to their manufacturers via a mobile phone network, to report performance parameters, upgrade software or for emergency assistance. As an example, in the United States, GM’s OnStar technology (siliconchip.com.au/link/aaqx) can activate an in-car microphone to see if the occupants need help after a crash. It can also be used to remotely unlock a car if the keys have been locked inside. If the car has been stolen, this microphone can also be used to assist the police in arresting the perpetrators. siliconchip.com.au Fig.12: the PITA device (Portable Instrument for Trace Acquisition), shown on top of a possible disguise for the device. The US FBI (Federal Bureau of Investigation) and other agencies realised that this could also be used to spy on people; however, a 2003 court ruling established that they were not allowed to do so. In 2015, a hacker demonstrated they could remotely locate, unlock and start a vehicle, but the company modified the system to prevent this happening in future. Mobile phone tracking Mobile phones users can be tracked by methods including: 1) With the cooperation of the service provider, it is possible to determine which base station a handset is closest to and the adjacent ones and, with knowledge of the power levels and antenna patterns, a location fix to within about 50m can be obtained in urban areas. 2) A handset can broadcast its location, determined either by a GPS receiver or by knowledge of signal strengths and triangulation from nearby towers. 3) The location of a handset can be established by nearby WiFi networks. The phone requires software to do this, which is widely available. 4) Specific Apps on the phone can send one’s location to others (eg, one called Life360). This can be useful for knowing when family members will get home or coordinating meetings, but of course, there is also the possibility that malicious Apps could do the same. It is also possible to use these location methods to find an injured person, as happened recently in Australia, where a car ran off the side of the road and the driver did not know where they were. They rang emergency services using a mobile phone, who were then able to use the phone to locate them. Note that almost all telecommunications and Internet activity is recorded by or for the government in Australia, most recently under the Telecommunications (Interception and Access) Amendment (Data Retention) Act 2015. For details on this, see the following web page: siliconchip.com. au/link/aaqy The author recalls how the introduction of the GSM network in Australia, finally activated in 1993, was significantly delayed until Australian Government agencies were given the means to access communications going through that network (this was widely reported at the time). Signal Amplification Relay Attack (SARA) This attack works against anything with proximity key- Australia’s electronics magazine September 2019  21 tenna can be used for picking up higher frequency signals. This attack only works for certain cars (but there are millions of them on the road), and it requires another SARA attack to start the engine or reprogram the vehicle to accept a new key. It is suggested that criminals don’t need to start the car a second time, as they drive to a location and strip the car or use it once for a crime like a bank robbery etc. Other forms of “relay” attack work similarly. Many vehicle thefts have been documented which are either known to or appear to have used a SARA attack, including many expensive cars. See the video titled “Car Theft: Key Fob Relay Hack Attack Explained” at: siliconchip. com.au/link/aaqz Fig.13: a simplified scheme of the SARA relay attack. Source: Francillon, Danev and Capkun, Department of Computer Science, ETH Zurich. less entry, such as many modern cars, and some building entrances or garage doors. It does not require possession of a key, just a knowledge of its approximate location. It works by making a long-range connection between a legitimate owner’s key fob and the point to be accessed – see Fig.13. This attack primarily works on systems that do not require a button on the key/card to be pressed to gain access, but rather, simply require its proximity to the lock or a button press on the lock itself. This is because systems where a button is pressed on the key require access to the key. Many cars use a system known as Passive Keyless Entry and Start (PKES), although others are also used. The principle involved is that when the keyfob and vehicle are near to each other, an RF handshake occurs between the two devices. This handshake is encrypted and uses a rolling code, so just recording the exchange between the two devices will not allow you to gain access later. However, SARA emulates the key possessor being near the vehicle or door, when in fact they are far away (say, 100m). This allows the attackers to unlock the door without having the key. A simplified explanation of how PKES works is as follows. The car or other access point regularly emits a low frequency (LF) probe signal of 120-135kHz, which is picked up by the key’s paired RFID chip when it is less than 2m away. This then activates a microcontroller in the key, which opens a UHF channel and completes a rolling code authentication with the vehicle. The doors can be opened or, if the key is detected as being inside the vehicle, the engine can be started. Other systems may have the key respond on an LF band rather than UHF. A PKES attack first requires two devices, one near the car, the other within range of the keyfob. A long-range communications channel is then established between the two. The device near the car captures its LF emission and converts it to a convenient frequency, such as 2.5GHz. This is then received by the device near the keyfob and downconverted back to the original LF frequency. The key fob then reacts in the usual manner, and its UHF transmissions are picked up and relayed back to the other unit, and the rolling code exchange can be completed over the relay channel, as if the key is close to the vehicle. A loop antenna is used at both locations to inject and receive the LF signals from the car and key, while a standard UHF an22 Silicon Chip CREATING VULNERABILITIES IN HARDWARE IBM Selectric typewriter keystroke logging In 1984, it was discovered that from 1976-1984, 16 IBM Selectric typewriters used in the US Embassy in Moscow and the US Consulate in Leningrad had been fitted with what would today be called a key-logging system. These typewriters were electromechanical, with no electronics, so this was not a traditional form of hacking (see Fig.14). The attack was highly sophisticated and much more complex than the Soviets were thought to be capable of. The possibility that the typewriters might be bugged was only established after the French discovered one of their teleprinters had been bugged, and alerted the Americans, which lead to the “GUNMAN Project” to find these and other bugs. These typewriters used mechanical binary coding to move the ‘golf ball’ print head. The position of the six “latch interposers” on the typewriter had been modified, and a magnet added. The bug had magnetometers that could sense the position of the latch interposers, which had encoded on them a 6-bit binary value which the bug compressed to four bits and then transmitted (Fig.15). The bugs had special circuitry to evade standard bug sweeps, such as with non-linear junction detectors. It is likely enemy agents had obtained access to the typewriter somewhere along the supply chain to install the bugs (see Fig.16). The operation of the bug is quite complicated and there Fig.14: the IBM Selectric electric typewriter from the 1960s, showing its unique ‘golf ball’ print head. The “bugging” of these was the first known instance of key-logging for espionage. It used mechanical binary coding and mechanical digitalto-analog converters to detect the character on the golf ball being typed, then transmitted this information to a remote location. Australia’s electronics magazine siliconchip.com.au Fig.15: this shows how the Selectric bug worked, including conversion of the mechanical 6-bit binary code to a 4-bit value for transmission. Image source: Crypto Museum (www.cryptomuseum.com) is insufficient space for a full description here. See the following website for the only detailed description of its operation on the web: siliconchip. com.au/link/aare The full fascinating story can be read in the declassified document “Learning from the Enemy: The GUNMAN Project”, United States Cryptologic History, Series VI, Vol. 13 at: siliconchip.com.au/link/aaqo Jumping the “Air Gap” Computers which require very high security are protected by an “air gap”, which basically means that the only wires running to and from those computers carry power; there is no network connection to prevent hackers from accessing the systems or getting data out. Usually, people with access to air-gapped computers are also subject to strict rules about carrying USB drives, optical media, smartphones and so on, to prevent a bad actor from stealing the data. But Israeli researchers at the Cyber-Security Research Center at the Ben-Gurion University of the Negev have devised methods by which data can be extracted from an air-gapped computer. See the video titled “The Air-Gap Jumpers” at: siliconchip.com.au/link/aar0 Generally, these methods require the computer to be compromised in some manner beforehand, possibly before it is even installed, or via malware on a USB drive smuggled in. Data can then be transmitted to remote locations, despite the lack of networking. * LED-it-GO: a computer’s hard drive activity light can be made to blink on and off in a Morse Code-like pattern. See the video titled “LED-it-GO. Jumping the Air-Gap with a small HardDrive LED” at: siliconchip.com.au/link/aar1 * PowerHammer: a method by which the power consumption of the computer is altered by varying CPU utilisation. The variations encode the desired data. Power consumption can be monitored via associated wall power outlets and data extracted at the rate of 1000 bits/second, or by measuring phase angle changes at the electrical junction box, at 10 bits/second. * MOSQUITO: malware on the target computer transmits data via its speaker to the other computer at 18-24kHz, which is not audible to most people. A second computer, up to 9m away, uses its onboard speaker as a microphone to pick up that signal. See the video titled “MOSQUITO: Jump air-gaps via speaker-to-speaker communication” at: siliconchip.com.au/link/aar2 * ODINI: this attack allows data to be extracted from a computer even when it is in a Faraday cage, which blocks most electromagnetic radiation. The exploit is based on the fact that only higher frequency radiation is blocked by the cage, not low frequency or static magnetic fields. (For example, a compass will still siliconchip.com.au work in a Faraday cage.) Malware on the target computer is used to generate slowly varying magnetic fields by regulating the CPU load. A sensor external to the Faraday cage can detect the magnetic field variations and receive the desired data. See the video titled “ODINI: Escaping data from Faraday-caged Air-Gapped computers” at: siliconchip.com.au/link/aar3 * MAGNETO: similar to ODINI but uses the magnetic sensor of a smartphone for the receiver. See the video titled “MAGNETO: Air-Gap Magnetic Keylogger” at: siliconchip. com.au/link/aar4 * AirHopper: uses malware to generate encoded FM radio signals via a computer monitor, to be received by a smartphone. See the video titled “How to leak sensitive data from an isolated computer (air-gap) to a nearby mobile phone – AirHopper” at: siliconchip.com.au/link/aar5 * BitWhisper: malware which varies the heat output of the target computer, which can be picked up 40cm away. Allows the extraction of data such as passwords at the rate of 1-8 bits per hour. Fig.16: modified power switches from Selectric typewriters, showing how power was diverted to run the bug. There were multiple generations of the bug, and this modification was not used in all of them. Some of the bugs were battery powered instead. Australia’s electronics magazine September 2019  23 Fig.17: part of the OR1200 CPU (left) showing the tiny altered region involved in the A2 malicious hardware attack. One μm is one-thousandth of a millimetre. See the video titled “BitWhisper - Jumping the Air-Gap with Heat” at: siliconchip.com.au/ link/aar6 * GSMem: malware which generates radio signals via specific memory instructions, which can be received by a mobile phone. See the video titled “GSMem Breaking The Air-Gap” at: siliconchip.com.au/link/aar7 * DiskFiltration: malware generates ultrasonic audio signals via the hard disk actuator arm, so it can be used on computers without speakers. See the video titled “DiskFiltration: Data Exfiltration from Air-Gapped Computers” at: siliconchip. com.au/link/aar8 * USBee: utilises malware and an unmodified USB device to generate encoded radio signals that can be received and decoded using GNU Radio (opens source software radio). See the video titled “USBee: Jumping the air-gap with USB” at: siliconchip.com.au/link/aar9 * Fansmitter: malware which can transmit acoustic data from a speakerless computer via modulation of cooling fan speed, which can be received up to 8m away at a rate of 900 bits per hour. See the video titled “Fansmitter: Leaking Data from Air-Gap Computers (clip #1)” at: siliconchip. com.au/link/aara * aIR-Jumper is an optical and infrared exploit using malware to control the infrared illuminators of security cameras on the same network, allowing bidirectional communication over distances of kilometres; see the video titled “leaking data via security cameras” at: siliconchip.com.au/link/aarb * xLED: malware which extracts information by observing encoded data sent via the LED status lights of a network router. It can be observed remotely using a telescope, at 1-2000 bits per second. See the video titled “xLED: Covert Data Exfiltration via Router LEDs” at: siliconchip.com. au/link/aarc * VisiSploit: malware which encodes data on the computer’s LCD screen in a way not perceptible to humans (eg, fast flickering), but which can be recovered by viewing the LCD with a remote or hidden camera (“Optical air-gap exfiltration attack via invisible images” is another similar technique). * LCD TEMPEST: malware which encodes data as radio signals generated by the computer’s video cable, which can then be received via GNU Radio at 60-640 bits per second. ers called A2, was shown to work because typically, chip designers do not have full control over their design. Once a CPU or other chip is designed, it is sent to a third party for manufacturing. The chip development company ensures their design has not been tampered with by testing the fabricated chips, to ensure they behave as intended. But in this particular attack, the malicious circuitry was only activated by an extremely unusual sequence of events repeated multiple times, that the original designer could not possibly envisage or test for. In the scenario tested by researchers K. Yang, et al, they modified the circuit by adding capacitors into the chip circuitry or “mask” which siphoned off power from nearby wires as they transitioned from one logic state to another. But this only occurred during the execution of an unusual operation, which could easily be triggered by the attackers. When those capacitors eventually gain full charge, they cause a transition of the state of a selected flip-flop that holds the ‘privilege bit’ for the processor, enabling full control of the computer by any user. The attack was tested on an open-source chip design (OpenRISC 1200 CPU – see Fig.17) but could be adapted to virtually any CPU. Because this sort of attack is possible, companies with suspect behaviour have been banned or restricted from certain activities by governments. For example, Chinese manufacturers Huawei and ZTE have been banned in Australia from involvement in the 5G Manufactured devices with design altered for espionage Installing malware or hardware exploits into computer systems is bad enough, but consider that a “backdoor” could be built into a CPU or other important chip like a GPU (graphics processing unit). It would be virtually undetectable. This exact scenario was tested at researchers at the University of Michigan in 2016. This attack, which the research24 Silicon Chip Fig.18: the announcement that Huawei and ZTE have been banned by the Federal Government from providing 5G technology in Australia. Australia’s electronics magazine siliconchip.com.au Fig.19: the claimed Chinese espionage chip supposedly found built into Supermicro motherboards, along with pencil for size comparison. It is now doubtful that such a chip actually exists, but such an attack is theoretically possible. network due to security concerns (Fig.18). The Federal Government has a general guideline that says there is too much risk using companies that are “likely to be subject to extrajudicial directions from a foreign government that conflict with Australian law”; see: siliconchip.com. au/link/aard The concern is that there might be pressure from the Chinese government for these companies to install backdoors into the equipment, which could later be used for espionage (eg, listening to ministers’ private conversations). The government has made no direct public statement advising of the ban, but the affected companies were informed. Huawei has also been in the news recently as being banned from doing business with the United States over similar concerns. Huawei and ZTE were also investigated by the US House Intelligence Committee in 2012 over concerns that their equipment might be sending intelligence back to the Chinese government. The Committee recommended that US companies should not purchase telecommunications equipment from either company as a result. ZTE eventually had US their restrictions on US trade relaxed in exchange for paying a US$1 billion fine, as well as a nearly complete management change, and overwatch from a US compliance team. Currently, the only restriction placed on ZTE by the USA is that their devices will not be considered in US government purchasing contracts. The ZTE trading ban was in retaliation for selling their products to Iran and North Korea but ZTE is and was a lot more dependent on US manufacturers for chips than Huawei. Thus, the damage to ZTE was greater and they were therefore more keen to have that ban lifted. See: siliconchip.com.au/link/aaso and siliconchip.com. au/link/aasp Equipment intercepted and altered before delivery In 2002, the Chinese claimed that a Boeing 767 purchased from the United States to serve the Chinese President Jiang Zemin yielded a total of 27 bugs, which they claimed had been planted by the CIA when the aircraft was undergoing conversion work to a VIP aircraft in Texas. As with the 767 incident, other devices can be intercepted and altered for espionage purposes at some point between manufacture and delivery of the item to the end user. In late 2018, there was a claim by Bloomberg News that US computer server manufacturer Supermicro had been compromised by the manufacturer in China, by the insertion of a tiny espionage chip that could enable the transmission of data on the computer or its network to malicious actors (see Fig.19). This claim has since been thoroughly investigated and is now widely believed to be untrue. Investigations were siliconchip.com.au conducted by companies including Apple and Amazon, who were Supermicro customers, and the US Department of Homeland Security and the UK’s National Cyber Security Centre. Supermicro’s reputation has still damaged though, and they note the difficulty of proving a negative (ie, that the malicious chips don’t exist). But that does not mean that this particular method is impossible. NSA Cisco router hacks Security documents and photos were leaked depicting a US NSA “upgrade” facility called TAO (Tailored Access Operations) for Cisco devices and other tech devices. It was claimed the NSA would intercept shipped devices and used this facility to install backdoors or similar exploits, before delivering the products to the end users, who were presumably unaware that the product(s) had been altered. See: siliconchip.com.au/link/aasq and siliconchip. com.au/link/aasr Rowhammer and RAMbleed Rowhammer is an exploit involving DRAM memory, in which the memory cells inadvertently leak electrical charge into adjacent cells, thus causing those cells to change their contents. This leakage effect rarely or never occurs in DDR or DDR2 type SDRAM modules, but is known to occur in some DDR3 and DDR4 modules because of their much higher chip density. Normal leakage of the electrical charge representing a memory state is usually compensated for by regularly rereading the memory element and then rewriting the data. This is called ‘refreshing’ and is normally done every 64ms. But with Rowhammer, there is a forced repeated reading and refreshing of memory elements, with use of the Cache Line Flush (CLFUSH) instruction causing adjacent memory elements to flip. This is normally prevented by caching limits, but these limits are overridden by CFLUSH. The deliberate altering of data in adjacent memory rows has been used as a basis for the attacker to gain extra access privileges in the system under attack such as by altering control structures in memory. In one implementation of a Rowhammer attack, sensitive data such as passwords can be extracted from the leaking memory cells. Rowhammer cannot be easily fixed with security software or operating system updates, and perhaps not at all. The RAMbleed attack uses Rowhammer to identify bits that can easily be flipped, even when ECC (error-correcting code memory) is used. These flippable bits are used to read out the desired memory contents. A researcher who discovered this vulnerability, Yuval Yarom (University of Adelaide) described RAMBleed as “a side-channel attack that enables an attacker to read out physical memory belonging to other processes”. RAMbleed can be theoretically used to read any data in physical memory. A read rate of 3-4 bits per second has been demonstrated. Therefore, data such as passwords or encryption keys can be read in a relatively short time if the location of the data in memory is known. SC Next month, as promised in the intro, we’ll have the details on many more electronic spying techniques, especially bugging and covert surveillance. Australia’s electronics magazine September 2019  25 Micromite-based 4DOF Simulator Seat Playing a car racing game (or if you prefer, a driving simulator) on a big screen can be thrilling. Plus it’s a lot cheaper and safer than taking your car to a racetrack! But it’s a lot more exciting if you can actually feel the motion and forces as you accelerate, brake, corner and drive up/ down hills or banked tracks. Build this four-degree-of-freedom racecar seat and experience that motion, without spending heaps! It works well with flight simulators, too. I f you’re really into racing games or driving simulators, you’ll want a seat like this, which moves to simulate the motion of the vehicle you’re ‘driving’. It can also give you some sensation of motion with a flight simulator, although obviously, it can’t quite simulate barrel rolls and loops! You can go out and buy one right now (or order it online), but you could easily spend thousands of dollars on a good one. If you have some mechanical and electronics skills, and are interested in a bit of a challenge, you can build your own for a fraction of the price. And in this article, we explain just how to do that. You can see the sort of results you can expect to get if you build this seat by watching the following short video: https://youtu.be/tn9LW758emc That video shows a racing simulation game called rFactor (available on https://store.steampowered.com), actuating the seat using the SimTools software (link at the end of this article). Micromite-based The electronics, whose job is to inter26 Silicon Chip by Gianni face with your PC, retrieve data from the simulation and then drive the motors in the seat to the required angles. It’s set up using a touchscreen interface. And it’s all based on a familiar module to SILICON CHIP readers: Geoff Graham’s Micromite processor. The electronics module can control the motors in the seat using off-theshelf motor driver boards, or even better (and much cheaper!) you can build your own, as described later. The seat itself is a bucket seat as installed in many race cars, or even street cars. They are widely available and not terribly expensive (try a wrecker who might have just what you want!). Of course, if you want to use a famous brand seat (like a Recaro) be prepared to pay just a little more! The seat’s supporting structure is built mainly from steel tubing, plates and MDF, with linear bearings to allow it to move forward and back and simple ‘bearings’ made from caster wheels and tubes to allow it to pitch forward and back, yaw from side to side and roll from side to side. Between two and four motors provide the motion, depending on how many ‘dePallotti grees of freedom’ (DoF) you want. Australia’s electronics magazine siliconchip.com.au MICROMITE 4DOF AXES CONTROLLER Roll Up POWER SUPPLY “Pitch” Down PIC32MX170F256D Yaw H-BRIDGE Forward “Surge” POLOLU 758 Back WIPER MOTOR WIPER MOTOR Fig.1: apart from the mechanical side, which we’ll get to shortly, here are the electrical components of the simulator seat and are described in the text. The motors are worm drive (12V or 24V wiper motors, for example) which can be obtained at low cost from an auto wrecking yard. The panel below shows and explains the six basic degrees of freedom, while Fig.2 shows those motions the most complicated version of the seat provides. With a driving simulation, turning the vehicle normally causes some degree of yaw, sway (pitching sideways) and possibly also roll (pitching forward/back). Acceleration and deceleration cause changes in pitch (to simulate suspension compression) and surge (forward/ back motion), while driving over bumps or elevation changes (ie, going up or down a hill) causes heave (up/down) movements. The use of a standard seat slider mechanism provides a reach adjustment for the pedals, steering and gear controls (slider frame), so that you can customize it to suit each individual driver. Additionally, the seat can be relocated forward or backwards through additional holes on the main frame. It also provides a reach adjustment for the pedals and other controls, so that you can customise it to suit each individual driver. WHAT IS DoF? The are actually six Degrees of Freedom, which allow you to experience just about any force you’re likely to encounter. All relate to the possible movement of a ship at sea or an aircraft/spacecraft in flight. These are: Roll Right Yaw Left Pitch SC 2019 Down siliconchip.com.au The seat assembly can be built in three different versions, with two, three or four degrees of freedom. The three DoF version cannot move forward or backward but can tilt forward, back, left, right and yaw. The two DoF version cannot yaw either, and can only tilt forward, back, left or right. Essentially, the two DoF seat is made into a three DoF seat by the addition of a “swivel/yaw frame”, including a third motor which causes the back of the seat to swing from side to side. The three DoF seat is turned into a four DoF seat by the addition of another base (made from MDF) DoF – Degrees of Freedom – refer to the directions you (or more properly, your craft) can move (in this case, simulated by our seat). Up Forward Fig.2: the four ‘degrees of freedom’ which allow you to experience just about any force you’re likely to encounter while in a moving vehicle. The seat described here can provide all degrees of freedom except for left/right and heave (although its up/down axis does provide some degree of heave motion). Move up and down (elevating/heaving); Move left and right (turning/swaying); Move forward and backward (accelerating/braking or ‘surging’); Swivel left and right (yawing); Back Tilt forward and backward (pitching); Pivot side to side (rolling). Our simulation seat has four of these motions: up/down (heave), forward/back (surge), swivel (yaw) and roll. The ‘heave’ motion is implemented by moving the front of the seat up and down on both sides at the same time, while roll is provided by the differential vertical motion of the front of the seat between the left and right sides. Australia’s electronics magazine September 2019  27 Fig.3: the four main subframes: from left to right, the yaw base/swivel frame (not required for the two-DoF version), the main frame, the seat frame and the slider/steering frame. The majority of mechanical construction work in building the seat involves fabricating these four sub-frames. They are made mostly from steel tubing, plates, angle, flat bar and a few brackets. You will need some welding skills to do a good job. with linear bearings and a motor, so that it can slide forwards and backwards. The two-DoF version is the easiest to build, especially if you omit the seat slider adjustment. It’s possible to upgrade a two-DoF version to the three-DoF version later, and similarly, to upgrade the three-DoF version to the four-DoF version. The four main subframes are shown in Fig.3. The yaw base (not required for the two-DoF version), the main frame, the seat frame and the slider/steering frame are arranged in a stack, with the bottom frame on top of the yaw base, the seat frame on top of the bottom frame and the slider frame hanging from the seat frame. Building the seat frame/assembly This is a job which requires some significant fabrication skills and tools. Most of the components are made from steel, which can be cut using a metal cut-off saw or manually (and slowly!), with a hacksaw. The 6mm plates used to attach the electric motors are the only plates requiring actual shaping. Any metal supplier The seat frame with the bucket seat removed 28 Silicon Chip can cut these. It can be done manually, but it’s hard work! The other mounting plates are either fabricated from blank metal plates or made up using standard off-the-shelf brackets. There is a need to machine special bushes and rods to suit the spherical bearing and universal joint unit. These should be made to fit the selected components. The two rear caster wheels on the swivel base are attached using spherical bearings to reduce friction, and the shaft holes must be re-drilled to keep the correct horizontal height of the frame. Nylon solid wheels (not rubber) can also be used, although this will increase the power demand from the motor. In this case, the two angle holes to the main frame wheel also need to be re-located to maintain the correct horizontal level of the main frame. For the simulator frame to swivel, the body of the larger caster swivel wheel base is used. The wheel housing needs to be cut and welded to the swivel base. To allow a smoother swivel movement, it would be better to remove the ball bearing from the large caster swivel A view of the universal joint connecting the seat frame to the main frame. Australia’s electronics magazine siliconchip.com.au C 120 16 7 24° A 300 800 SLIDER BASE C 205 395 380 A G C C C A H 300 340 H 1071 134 ALL DIMENSIONS ARE IN MM F 130° 518 SLIDER & STEERING FRAME B 72° 149 1 October 2019  29 185 282 12 H G A E 40° C 82 518 I 340 FOOT PLATE B E B E 340 F D 500 134 SC 2019 SLIDER STEERING D B F E 149 800 30 base and introduce a double raw-angular contact bearing or similar, with a dedicated spindle. But that would require a dedicated housing design. The caster swivel base used is the easiest solution and works well. Figs.4-7 show the details of how each subframe is made, while Fig.8 shows the MDF pieces which need to be cut and shaped for the table which holds the steering wheel and gearshift lever, and the floor base, which is only needed for the four-DoF version of the seat. Fig.9 shows the assembled seat (four-DoF version) from two different angles while Fig.10 shows a 3D view of the completed assembly (3 DoF). You can also refer back to Fig.3 and the photos throughout this article during construction in case you have trouble figuring out exactly how the various pieces fit together. We won’t go into exhaustive detail on the construction steps here, partly because there are various ways you can go about it, and partly because we expect constructors with the tools and skills to be able to do so should be able to figure it out from the CAD drawings and diagrams. Most parts will need to be welded, although some parts are bolted together, and generally, the holes which need to be drilled for these bolts are shown in the drawings. Drill 12mm holes for M10 bolts, 10mm holes for M8 and 8mm holes for M6. Once you have built the subframes, given them a good coat of black paint for rust prevention (and to make it look good), put them together and then you can start mounting up the motors and fabricating the linkages to attach them to the frame where required. If building the three-DoF version, it’s easiest to completely build and test the two-DoF version first, then add the yaw base, motor and linkages and test that separately. Similarly, to build the four-DoF version, build and test the three-DoF version and then add the floor base, linear bearings, forward/back motor and linkages, then wire that up and test the final product. Once you’ve built the frame and attached the motors, you will need to build the controller module and obtain a suitable power supply before you can wire up the motors and test it properly. Make sure you attach the punched angle rail to the slider frame (“foot plate retainer”), even if you aren’t using the chequerplate foot plate, as it adds needed rigidity. The CAD drawings do not show how this is mounted, but you can see it in the photos. J FOOT PLATE RETAINER (x2) Fig.4: the slider and steering frame provides a place to mount the steering wheel, gear shift lever and pedals, while allowing them to be moved forward and back, to suit users of different heights and sizes. It’s a good idea also to fit the foot plate, to give you somewhere to rest your feet (it looks nice, too). 583 SC Fig.5: the bucket seat is mounted on the 12 x 12mm diameter seat frame, and P 38 holes to attach seat can be moved forwards or K M backwards 4 x 8mm O into one of diameter three positions holes to L N L attach through extra slider O bolt holes. This frame also provides 280 K attachment points for the 320 P slider and          steering frame and also the caster wheels          which roll on the optional swivel frame. N 2019 152 K P siliconchip.com.au Australia’s electronics electronics magazine magazine Australia’s 524 95 380 The additional adjustment holes allow 25mm further movement of the seat frame assembly. 355 110 81 SSeptember eptember 2019  29 2019  29 200 You can cut the MDF components using a jigsaw and laminate the edges with PVC edge banding tape and a hot air gun. 225 W V U 70 108 T T U R Adjustment and weight handling Q There are two options to assemble the seat and slider frame, depending on whether a standard seat slider is used or not. If using a seat slider, this is bolted between the seat bottom and top of the slider/steering frames. Unlike in a vehicle, instead of moving the seat itself, it moves the sliding/steering frame back and forward. The seat frame/slider frame is bolted to the pedal frame, while the slider top rail is bolted to the seat frame. This allows the foot frame to move forward or back as needed, with minimal disturbance to weight ratio balance of the unit as the seat stays close to the universal joint pivot point. There is a further 25mm forward or backward step adjustment on the seat frame, as there are three sets of holes in the seat frame to which the seat can be bolted. This can be used to offset user size or weight differences. I have tested the rig with a 120kg, 1.75m tall individual, and both the frame and the motors were able to cope without any problems. S 765 W 300 U 123 V U T 61° V Q 510 U T T R 750 U 391 S 100 650 108 V Q W U Controller circuit U S SC V 2019 Fig.6: the seat frame mounts on top of this main frame, which provides attachment points for the two front motors and also the caster wheels, which roll on the optional yaw base below. <at> 185 2019 5 40 40 15 8 SC 113 2 6 40 <at> X 335 7 75 280 5 350 2 Y 305 Z $ X 200 120 <at> 12 30 8 <at> 755 40 RETAINING WHEEL 16 6 LINEAR BEARING BRACKET 7 45 700 R887 The controller circuit is shown in Fig.11. This excludes the four motor controllers, which will be described separately later. You have a couple of options when it comes to those motor controllers. The job of this circuit is to receive data from the simulation running on a PC via a USB port, then perform some calculations to determine how the motors need to be driven to move the seat appropriately. It must then produce the appropriate drive signals to send to those motor controllers. All of this work is done by the software running on IC1, a 44-pin SMD PIC32 processor programmed as a Micromite. The aforementioned software is therefore written in MMBasic. Data from the PC comes in via a USB/serial adaptor that is wired up to CON1. The data then goes from CON2 to CON4, via a pair of jumper wires (blue/green dashed lines). CON4 connects to pins 8 & 9 on IC1, which are configured as a second serial port (ie, not the same one used for the <at> 5 8 <at> Z 8 2 <at> Z WHEEL HOLDERS 3 25 30 Fig.7: the yaw base/swivel 3 frame allows the main 100 20 20 frame above to rotate around 146 the front pivot point made from a caster swivel wheel. 60 50 It rides on two caster wheels attached to the angle bar which roll on the angled metal plates at the back of the frame. This also provides a mounting point for the yaw motor. 30 30  S Silicon Chip A view of the typical linear bearings and shaft used for the forward/backward motions. Australia’s Australia’s electronics electronics magazine magazine siliconchip.com.au 280 225 $ $ 130 445 1100 340 450 % % Motor $ FLOOR BASE (FORWARD/BACK) % Fig.8: these pieces, cut % from 16mm MDF, provide a SC 2019for the steering wheel and gear table shift lever, and the optional floor base which is needed for the fourth (forward/back) degree of freedom. BUCKET SEAT GHEPARDO (ADJUSTABLE) A view of the aluminium plate used as a footrest, installed on the slider/steering frame. siliconchip.com.au 355 150 115 $ 200 200 STEERING & GEARSHIFT TABLE 470 Micromite console & programming). To program or reprogram the Micromite software, the jumper wires connecting CON2 to CON4 are changed to connect CON2 to CON3 instead, so that the USB serial port accesses the Micromite console. During regular operation, the software reads in and processes the data from the USB serial port on the PC. It then generates control signals on digital output pins 1-4, 15 and 21-23. Pins 15 and 21-23 carry PWM signals which determine the torque/speed for each motor, while pins 1-4 control the direction of motor rotation. These signals go to pin headers CON8a-d and header sockets CON9a-d – these interface to one of two types of motor controller. CON8a-d suit pre-built modules, the “Pololu High-Power Motor Driver 18v25” while CON9ad suit a module that you can build yourself, for considerably less than the Pololu modules cost, described later in this article. It’s a slightly revised version of my design published in the Circuit Notebook section of the November 2017 issue (page 80). The main difference is a slightly changed layout to better suit plugging into the controller board used for this project, plus a slight simplification which removes two redundant resistors. While not shown in Fig.11, the board has two two-way terminal blocks to feed +13.8V and 0V from a high current supply into the board, for distribution to these four motor controller modules (see Fig.13). The motors are wired directly to the output sockets on the motor driver modules. If using my motor drivers, because they have three control inputs, rather than the two of the Pololu modules, you need an extra inverter for each driver. This is provided by IC2, a 74LS14 hex inverter. It converts the direction signals (low for one direction, high for the other) into two signals, with one going high for rotation in one direction, and the other going high for rotation in the opposite direction. CON6 is a 14-way header to connect to a 2.4in or 2.8in touchscreen based on the ILI9341 controller chip, which is the same screen used in the Micromite LCD BackPack and V2 or V3 BackPack. This is used to set the unit up and to monitor its operation. See the screen grabs below to see how the screen is used. It’s critical to calibrate the motor control scheme properly. Australia’s electronics electronics magazine magazine Australia’s Fig.9 (below): when the four main frames, seat, table, steering wheel and pedals are all joined together, they should look something like this (4DoF version). LOGITECH G27 STEERING FRAME NOT SHOWN SSeptember eptember 2019  31 2019  31 Fig.10: here’s a 3D view of the four main frames (not including the floor base or motors) as they appear when fully built and assembled. Other connectors CON5 is an in-circuit serial programming header which is compatible with the Microchip PICkit 3 and PICkit 4, although you could also connect it to a Microbridge (see the May 2017 article; siliconchip.com.au/Article/10648). This is necessary if you purchase a blank PIC32 microcontroller. If you purchase a pre-programmed micro from the SILICON CHIP ONLINE SHOP, you can get away without this header. Power is fed into the unit via CON7. It must be a regulated 5V, and this supplies the LCD screen at CON6 directly, both for logic power and to run its backlighting LEDs. (Initially the plan was to supply power via CON1 from the PC’s USB port but we found that the voltage drop caused by the long cable between the rear end of the chair and the display (about 2m) caused the display to misbehave. So it is best fed in via CON7). The 5V rail is also regulated to 3.3V by LDO REG1, to power microcontroller IC1. CON10 allows a DS18B20 temperature sensor to be connected to the board, so that the unit can shut down if the board temperature gets too high. If you use one of the DS18B20 sensors on the end of a A view of one possible mechanical link between the front motor shaft and the positioning potentiometer. 32 Silicon Chip wire, you could mount it in or on the power supply, or one of the motors, if you want. But if anything is going to overheat, it will probably be the motor drivers, so the ideal location for this sensor is in the middle of the M1 and M2 driver boards as these are the most heavily used. The pins of CON11 can be shorted to reset microcontroller IC1. It could be wired to a momentary pushbutton reset switch. CON12a-d provide connection points for the four motor position feedback potentiometers. Basically, as the motors rotate, the voltage at pin 3 of each of these connectors varies between 0V and 3.3V, and this is fed to analog input pins 27-24 of IC1, so it can use its internal analog-to-digital converter (ADC) to sense the potentiometer positions and thus drive the motors to a particular angle, just like a servo motor. LED1 is a simple power indicator to show when the 5V supply is present. And finally, CON13 is an auxiliary header which breaks out connections to four spare Micromite pins plus +3.3V and GND, and could be used for future expansion (such as adding a fan to simulate wind!). Pololu motor drivers Note that the Pololu motor drivers now being sold are somewhat smaller and cheaper than the versions shown here, but they do the same job and are drop-in replacements. These drivers enable bidirectional control of the highpower DC brushed motors used. These motor driver boards support a wide range of motor voltages, from 6.5V to 30V DC, and can deliver a continuous 25A. You can get these modules in Australia from RobotGear (http://siliconchip.com.au/link/aats) or Core Electronics (http://siliconchip.com.au/link/aatt). Or you can build your own H-bridge drivers, which are almost as capable... H-bridge driver circuit My own H-bridge module design is shown in Fig.12, which is very similar to the circuit published in the Circuit Notebook section of November 2017. The H-bridge is formed from two CSD18534KCS high-current logic-level N-channel Mosfets (Q3 & Q5) and two IRF4905 P-channel high-current Mosfets, Q2 & Q4. The rear bearing assembly. The retaining centre bearing prevents the frame from over-tilting during strong changes of direction of the swivel frame. Australia’s electronics magazine siliconchip.com.au An overall view of the assembled unit. The positioning of the motor links on the two lower frames is best determined once assembly is complete. Schottky diodes D1-D4 parallel the Mosfet body diodes and absorb any back-EMF or motor braking energy. They dissipate a lot less heat than the Mosfet body diodes because of their lower forward voltages. There’s also a local 100µF bypass capacitor across the motor supply. Zener diodes ZD1-ZD4 protect the Mosfet gates from excessive voltages, clamping them to about -0.7V and +15V. AND gates IC1a & IC1b combine the PWM and directional input signals to generate the gate drive voltages, and their outputs directly drive the gates of Q3 and Q5. These signals also go to the bases of NPN transistors Q1 and Q6, which form inverters to generate the drive signals for the P-channel Mosfets. These also act as level-shifters, so that when the signal from IC1a/IC1b is low, the gate of the associated P-channel Mosfet is held at V+, around 13.8V, to keep that Mosfet switched off. When the signal from IC1a/IC1b goes high, the baseemitter junction of one of these NPN transistors is forward-biased, and current flows through its 3.6kΩ base current-limiting resistor, causing it to switch on and pull its collector down to just a volt or so. This is well below the 13.8V at the source of Q2 and Q4, so one of those Mosfets switches on. The 1.5kΩ base-emitter resistors for Q1 and Q6 ensure that they switch off when there is no drive voltage, and as a result, all four Mosfets are kept off if the 5V supply is absent, even if the 13.8V motor supply is present. The 160Ω emitter resistors for Q1 and Q6 prevent them from fully saturating when switched on, so that they switch off faster when the base drive is removed. The exposed seat frame. The full frame, without the seat in place. siliconchip.com.au Building the control module The control module is built on a single-sided PCB coded 11109191. Use the overlay diagram, Fig.13, as a guide during construction. You can etch this at home, as I did, or you can buy a commercially-made PCB from the SILICON CHIP ONLINE SHOP. That board will be double-sided, with copper tracks on the top layer replacing the wire links, saving you considerable effort in fitting those links. Australia’s electronics magazine September 2019  33 CON7 DC IN +5V + 470 – CIRCUITRY IN THIS SHADED AREA V+ FF2 FF1 RESET- 8 5V 7 PWM 6 DIR+ 5 DIR– 4 GND 5 GND 47 F  LED1 K 4 3 2 2 1 14 1 IC2a 3 PWM 2 DIR 1 GND CON 9 b CON8b V+ 5V(out) FF2 FF1 RESET- 8 5V 7 PWM 6 DIR+ 5 DIR– 4 GND 5 4 3 2 4 1 3 CON4 IC2b 1 TX 3 PWM GAME 2 RX 2 DIR CON10 1 GND CON 9 c CON8c V+ 5V(out) FF2 FF1 RESET- 8 5V 7 PWM 6 DIR+ 5 DIR– 4 GND IC2: 74LS14 5 4.7k 3 TEMP SENSOR IN +3.3V 2 1 4 3 2 6 1 5 IC2c 3 PWM ICSP 2 DIR CON5 1 GND MCLR Vcc 5V(out) FF2 FF1 RESET- GND CON 9 d CON8d V+ 8 5V 7 PWM 6 DIR+ 5 DIR– 4 GND 5 PGD 4 PCC 3 2 1 +3.3V 3 4 5 6 IC2d 8 1 2 9 7 3 PWM 2 DIR K A CON8a-9d: For Pololu Drivers CON9a-9d: For DIY drivers SC 20 1 9 LM3940IT LED 1 GND GND IN GND OUT FOUR DEGREES OF FREEDOM MICROMITE-BASED MOTOR CONTROLLER The only slightly tricky part to solder is SMD microcontroller IC1. But it isn’t a particularly fine-pitched device, so it is not too difficult. You will need some good flux paste and a roll of solder wick, though. Start by locating its pin 1 dot and line this up with the pin 1 indicator etched into the copper on the bottom side of the board. Tack one of the corner pins to the board, for example, by applying a little solder to one of the pads and then sliding the chip into position while heating that solder. Check that the chip is square and all the pins are lined 34 +3.3V OUT IN 100nF A CON 9 a CON8a 5V(out) NOT REQUIRED IF POLOLU IS USED REG1 LM3940IT-3.3 +5V Silicon Chip up with their pads. If not, re-heat that initial solder joint and gently nudge the chip in the right direction. Once it’s correctly aligned, apply flux paste to all the pins, then solder the diagonally opposite pin from the one you tacked. Apply solder to the remaining pins. You can do this by loading the iron tip with some solder, then gently dragging it along one edge of the chip. Repeat for the other edges, then check for solder bridges across pins. If you find any, apply extra flux paste and clean them up with solder wick. Then use pure alcohol or flux residue cleaning solution to remove flux residue and inspect Australia’s electronics magazine siliconchip.com.au 9 10 11 T_IRQ 8 T_DO 7 T_DIN T_CLK 6 T_CS 5 SDO 4 BKL 3 SDI 2 SCK 1 D/C RESET 1 18 CS 2 RESET CON11 1k +5V 50k +3.3V GND +5V 12 13 14 CON6 ILI9341 BASED LCD DISPLAY 47 F +3.3V 17 AVDD 28 VDD 40 VDD AUX1 MCLR 1 2 3 4 RPB 8/PMD4/RB 8 RB9/RPB 9/SDA1/PMD3 RPB 7/PMD5/RB 7 RC 6 /RPC 6/PMA1 PGEC 3/RPB 6/PMD6/RB 6 RC 7 /RPC 7/PMA0 PGED3/RPB5/PMD7/RB5 CON13 18 6 44 5 43 4 42 3 41 +3.3V 2 1 38 IC1 RPC 5/PMA3/RC 5 5 PIC32MX170F 2 MX170F 37 RC9/RPC9/PMA6 PIC3 RPC4/PMA4/RC4 –256D 8 9 10 11 12 13 14 15 19 20 21 22 RC8/RPC8/PMA5 RB 10/RPB 10/PMD2/PGED2 RB 11/RPB 11/PMD1/PGEC 2 RPC3/RC3 TDI/RPA9/PMA9/RA9 RB12/PMD0/AN12 SOSCO /RPA4/RA4 RB 1 3 /RPB 1 3 /AN 11 SOSCI/RPB4/RB4 RA10/PMA10/TMS/PGED4 RA7/PMA7/TCK/PGEC4 RB 1 4 /RPB 1 4 /AN 10 TDO /RPA8/PMA8/RA8 OSC 2/CLKO /RPA3/RA3 OSC 1/CLKI/RPA2/RA2 RB15/RPB15/AN9 AN 8/RPC 2/RC 2 RA0 /AN 0 /VREF+ AN 7/RPC 1/RC 1 RA1/AN1/VREF– AN6/RPC0/RC0 PGED1/AN 2 /RPB 0/RB 0 AN5/RPB3/RB3 PGEC1/AN3/RPB1 /RB1 AN4/RPB2/RB2 VCAP AVSS 16 VSS 6 VSS 29 VSS 39 JP1 34 RX 2 33 TX 1 GND CON1 +5V 1 CON3 CON2 PROGRAM 32 +3.3V USB-SERIAL INPUT 36 35 PWM2B IN/OUT 31 2 2 3 1 4 5 30 6 27 +5V GND TX RX DTR +3.3V CON 12 a 26 3 25 +3.3V 24 2 1 23 POT – M1 CON 12 b 7 3 +3.3V 47 F 2 1 TANT. POT – M2 CON 12 c 3 +3.3V 2 1 POT – M3 CON 12 d 3 Fig.11: the control board circuit is relatively simple, thanks to the use of a PIC32 Micromite microcontroller (IC1) and four separate motor driver H-bridge modules, which connect via CON8a-d or CON9a-d, depending on the type. Motor position feedback comes from attached potentiometers, which provide variable voltage signals at CON12a-d. The blue and green dotted lines (CON2 to CON3 or CON2 to CON4) are where jumper leads are fitted to select between programming mode and game mode. the solder joints under magnification to ensure they are all good. Fitting the remaining parts If you have a single-sided board, the next job is to fit the 27 wire links on the top side of the board. They are shown in red on Fig.13. Don’t miss any, and if you are using uninsulated wire, make sure the links are taut so that they can’t easily bend and short to each other, or to the leads of adjacent components. Now fit the five resistors in place where shown on the siliconchip.com.au +3.3V 2 1 POT – M4 overlay diagram. It’s best to check each one with a multimeter before soldering it; you can identify them by the colour bands, but they are easily mixed up. Next, solder IC2 in place, ensuring that its pin 1 dot is orientated correctly. You can use a socket if you want, but it shouldn’t be necessary. IC2 can be left out if you are using the Pololu motor drivers. Install LED2, with its longer lead towards the closest edge of the board (marked “A” for anode on the PCB). Follow by fitting all the standard pin headers. Depending on how you are building the unit, some can be left out, Australia’s electronics magazine September 2019  35 Fig.12: the circuit of the DIY version of the motor driver (H-bridge) module. It uses four Mosfets to drive the motor in either direction, controlled by two small-signal transistors and a 74HC08 quad 2-input AND gate. This is only slightly different than the version previously published in Circuit Notebook. but they’re quite cheap, so it’s easier just to fit them all. If using the Pololu motor drivers, you can also fit the four 8-way female header sockets now. Follow by mounting polarised header CON7, then the capacitors. The electrolytic capacitors are polarised and must be orientated as shown. You can identify the positive lead as it is the longer of the two. The tantalum capacitor should also have a “+” marking on its body, while the aluminium electrolytics will have a stripe on the can showing the negative lead. You can now install the two terminal blocks along the left edge, with their wide entry holes facing the edge of the PCB, then fit regulator REG1 with its metal tab orientated as shown in Fig.13. Your touchscreen module should have come with a 14pin header pre-soldered to it. You can now connect this up to CON6 on the controller PCB using fourteen femalefemale jumper wires. You can get such wires joined together in a single ribbon cable, which would make the job a little easier (and neater). Pin 1 of CON6 is as the bottom, so make sure this goes to pin 1 on the LCD (pin 1 is +5V, pin 2 is GND) and that each pin is wired up in sequence. Use the two shorter jumper wires to connect Tx on CON2 to Tx on CON3, and similarly, Rx to Rx. Fit the shorting block on JP1 only if the controller is driven via the USB and LCD display installed close by (see our earlier comments about the display misbehaving with a long cable). Do not connect any other power source to CON7 (the LED will not light up). Solder the six-pin female header to the bottom of your USB/serial adaptor, so that its pinout matches that of CON1. Then plug this adaptor into CON1. Programming IC1 If you’ve purchased a preprogrammed Micromite chip, you can skip this step. Connect a PIC32 programmer to CON5, ensuring the pinout is correct (for a PICkit, this will be the case as long as pin 1 is lined up correctly). If using a PICkit, use MPLAB X IPE to load the 44-pin Micromite Mk2 HEX file into the chip, which can be downloaded for free from either the SILICON CHIP website, or Geoff Graham’s website (geoffg.net). If using a Microbridge, follow the instructions in the Microbridge article on using pic32prog to load a HEX file into PIC32. The file is the same regardless of the programmer you’re using. Loading the BASIC code You are now ready to connect this adaptor to your PC via a USB cable. LED1 should light up. Fire up a terminal emulator (or MMedit) and connect to the serial port which Here are the two motor drivers which suit our controller: on the left is the commercial “Pololu” driver, while at right is our DIY version (see Fig. 12 above). The DIY version, however, does require that IC2 is fitted to the PCB (see text). 36 Silicon Chip Australia’s electronics magazine siliconchip.com.au Fig.13: use this PCB overlay diagram as a guide to building the controller PCB. If you’re using a single-sided board, fit the wire links where shown in red. Otherwise, if you’ve purchased a double-sided PCB, that is not necessary. Note that the motor drivers shown here are now obsolete; the new versions are pincompatible but a fair bit shorter, so the supply wires will need to be a little bit longer. Also note that while this diagram shows the Pololu modules fitted, it also shows IC2. As explained in the text, you do not need IC2 with the Pololu modules – the diagram simply shows where it would be fitted if you are using DIY H-bridge modules. has now appeared at 38,400 baud (check Device Manager to see the newly allocated COM port number). Once you’ve established communication, use XMODEM or MMedit’s upload function to load the BASIC source code for this project into the Micromite chip. As with the Micromite firmware, the BASIC code is a free download from the SILICON CHIP website. You will then need to configure the touchscreen and set up the code to run on power-up by issuing the following commands: OPTION LCDPANEL ILI9341,L,36,32,35 OPTION TOUCH 30,31 OPTION AUTORUN ON GUI CALIBRATE Once you’ve finished calibrating the touchscreen, you can use the GUI TEST TOUCH command to check that it’s correct (touching the screen should leave a trail of dots), then cycle power and check that the splash screen comes up (see Screen1) and by touching the screen, the main screen (Screen2). Building the H-bridge module If you aren’t using the Pololu modules, you can build your own H-bridges using the double-sided PCB coded 11109192. Use the PCB overlay diagram, Fig.14, as a guide. Start by fitting the resistors where shown, except (for the moment) for the two 2.2kΩ, followed by the zener diodes, with the cathode stripes all facing towards the bottom of the board as shown. Next, fit schottky diodes D1-D4. Note that D3 faces in the opposite direction to all the other diodes. Also, since the diode bodies are quite large, you will have to be careful in bending the leads to fit the closely spaced pads on the PCB. Now solder IC1 in place, ensuring its pin 1 is in the correct location. You can use a socket, although we suggest you Top and bottom sides of the controller PCB, before the H-bridge drivers are attached (they slot into the header pin sets on the top side). While this single-sided board is ideal for home PCB makers, a double-sided version, which has all the links already in place as the top side pattern, is available from the SILICON CHIP ONLINE SHOP. IC2 is not required if Pololu drivers are used. siliconchip.com.au Australia’s electronics magazine September 2019  37 Part list - seat frame Pedal frame / slider 2 800mm lengths 20x20x1.6mm square steel tubing (A) 2 520mm lengths 20x20x1.6mm square steel tubing (B) 4 300mm lengths 20x20x1.6mm square steel tubing (C) 1 320mm length 20x20x1.6mm square steel tubing (D) 2 150mm lengths 20x20x1.6mm square steel tubing (E) 1 135mm length 20x20x1.6mm square steel tubing (F) 1 400mm length 25x25x3mm steel angle (G) 2 25mm lengths 25x25x3mm steel angle (H) 1 500x340x1.6mm rectangle of aluminium chequer plate (I) 2 800mm lengths of 30x30mm punched steel single slot angle rail (J) 10 M6 x 30mm machine screws and hex nuts (for attaching J to the slider frame). Seat frame 2 583mm lengths of 25x25x3mm steel angle (K) 2 355mm lengths of 25x25x3mm steel angle (L) 1 75x145mm rectangle of 6mm steel plate (M) 1 524mm length of 25mm diameter steel tube (N) 2 280mm lengths of 30x5mm flat steel bar (O) 4 M10 x 25mm machine screws (to join O to L) 6 M10 hex nuts (P) Main frame 1 750mm length of 40x40x1.6mm square steel tubing (Q) 1 650mm length of 40x40x1.6mm square steel tubing (R) 2 762mm lengths of 25x25x1.6mm square steel tubing (S) 2 300mm lengths of 25x25x3mm steel angle (T) 4 123mm lengths of 25x25x3mm steel angle (U) 2 142x100mm rectangles of 6mm steel plate (V) 1 215x100mm rectangle of 6mm steel plate (W) | not needed for 2DoF or 3DoF versions ~ Silicon Chip Fasteners and Linkages 6 55mm lengths of M10 threaded rod (for casters) # 12 M10 domed-cap nuts # 16 M5 x 12mm machine screws (for linear bearings) | 2 M6 x 15mm self-tapping screws (for retaining wheel) # 1 150mm length of M10 threaded rod (to swivel base) # 1 140mm length of M10 threaded rod (to MDF base) | 2 130mm lengths of M10 threaded rod (to seat frame) Bearings/wheels 8 M10 female swivel-head ball bearings 3 spherical insert ball bearings [NBR-SB201/12-40-22] 2 50mm diameter caster wheels (8) 1 heavy-duty swivel caster, 65x95mm minimum base size (wheel removed) (9) # 1 steering universal joint or prop-shaft UJ (from any car scrap yard) (for connecting the seat frame to the main frame) 4 linear ball bearings with rails (SBR12UU [block] & SBR12250mm [rail]) (%) | 4 Carinya 40x40 zinc-plated brackets (Bunnings Cat 0046902)(<at>) | not needed for 2DoF version; one only needed for 3DoF version solder it directly as some pins are soldered on the top side. Next, install the two 2.2kΩ resistors, which are mounted vertically, followed by transistors Q1 and Q6, with their flat faces orientated as shown. Also, before soldering the diodes, test fit the nearby Mosfets to make sure they will not get in the way. You may need to bend the diode leads a little to get them into a favourable position, where they clear the Mosfet bodies. Now solder the two 2-way terminal blocks in place, with the wire entry holes facing towards the outside, followed by the four Mosfets. As there are two different types, be careful not to get them mixed up, and ensure their tabs face as shown in Fig.14. Before soldering them, it would be a good idea to attach each pair to its heatsink, to ensure they line up correctly. Insert the insulating layer between the two pairs, then push them down as far as they will go and solder and trim the pins. Finally, fit header socket CON1 to the underside of the board, and it is ready for testing. Once you’ve completed the modules (you will need one for each degree of freedom that you are building into the seat), plug them into the main board. Note that the power supply terminals for this module are reversed compared to the Pololu module, so you will have to cross the wires over when you wire them up. 38 Swivel frame (|) 2 755mm lengths of 25x25x1.6mm square steel tubing (X) 1 700mm length of 40x40x1.6mm square steel tubing (Y) 1 350mm length of 40x40x1.6mm square steel tubing (Z) 1 305mm length of 40x40x1.6mm steel angle (2) 2 146mm lengths of 40x40x1.6mm steel angle (3) 4 40mm lengths of 45x45x5mm steel angle (4) 1 75x113mm rectangle of 3mm steel plate (5) 2 75x200mm rectangles of 3mm steel plate (6) 1 30x120mm rectangle of 3mm steel plate (7) # not needed for 2DoF version Wiring it up Luckily, this part is pretty straightforward. As you can see from the photos, I mounted the power supply for my rig at the back. I suggest you do the same. You will then need to run some thick (~25A-rated) wires, or a similarly rated figure-8 cable, from the supply up to the motor power terminals on the control board. Next, run a set of 10A-rated (or more) figure-8 cable from each pair of motor controller outputs to the appropriate motor. Motors 1 & 2 are at front left and right respectively. Motor 3 (if fitted) is the yaw motor, and motor 4 is the Fig.14: here’s how to fit the components to the double-sided DIY H-bridge board. For clarity, the heatsinks, mounting screws and insulating layer between the two pairs of Mosfets are not shown here. Refer to the photos of the unit for details on the heatsink mounting. It’s a pretty packed board, so don’t be surprised if you have to bend a few component leads to get everything to fit. Australia’s electronics magazine siliconchip.com.au Parts list - controller module 1 Dunnings 100x100x140mm angle bracket (Bunnings 1076757) | Motors/power 2 12V DC Fiat X1/9 lights retractor motors with 40mm radius action (roll) 2 24V DC garage sliding door motor with 40mm radius action (surge/yaw) ~ (worm-drive motors can also be used but are more expensive) 1 13.8V DC 40A power supply (Jaycar Cat MP3089) 2-4 100kΩ potentiometers (see text) MDF pieces 1 445x225mm rectangle of 16mm MDF ($) 1 280x130mm rectangle of 16mm MDF ($) 1 150x200mm rectangle of 16mm MDF ($) 1 1100x800mm rectangle of 16mm MDF ($) (floor base) | Other 1 Ghepardo fixed-back, five-way adjustable racing bucket seat 1 standard car seat slider mechanism (optional – see text) 1 set of Logitech G27 force feedback steering wheel and pedals Several metres of heavy-duty figure-8 cable Several metres of medium or light-duty three-core (or more) cable Connectors, to suit motors Total lengths of tube/angle/bar/rod 40x40x1.6mm square steel tubing: 1.1m 20x20x1.6mm square steel tubing: 4.6m 40x40x1.6 steel angle: 0.65m 25x25x3mm steel angle: 3.5m 30x5mm flat steel bar: 0.6m M10 threaded rod: 1m forward/back motor. Each motor must be fitted with a potentiometer to sense its shaft position. You need to wire the three connections for each potentiometer back to CON12a-CON12d on the controller board, ie, from motor 1 back to CON12a, motor 2 to CON12b etc. There are many different ways to connect these pots to the motors. Some motors have an extended shaft (for example, the two garage door motors I used). This allows placing the pot on one side of the shaft and the lever on the other end. Note that the arm lever length should not exceed 4550mm pivot to pivot, or the motor torque requirements may be too high. The RPM of a typical wiper motor will be around 50 revs/min. Wiper motors usually have the shaft extending only one one side, which will require a different mounting. The wiper motors unit pot uses a fork and spindle (a slide type mechanism). This allows full 180° rotation. But to avoid possible damage to the pots, I recommend opening the pots and flattening the wiper arm stopper. (see Fig.15). Additionally, do not attach any mechanical links yet – this is to avoid sudden and dangerous movement of any one of the actual chair frames. In each case, the pot wiper is wired to the connector siliconchip.com.au 1 single-sided PCB, code 11109191, 133.5 x 96.5m 3 6-pin headers (CON1,CON5,CON13) 5 2-pin headers (CON2-CON4,CON11,JP1) 1 14-pin header (CON6) 1 2-pin polarised header (CON7) 4 8-pin header sockets (CON8a-d; optional – for Pololu motor drivers) 4 5-pin headers (CON9a-d; optional – for self-built motor drivers) 5 3-pin headers (CON10,CON12a-d) 1 jumper shunt (JP1) 1 USB/serial adaptor (eg, CP2102-based; SILICON CHIP ONLINE SHOP Cat SC3543) 1 6-pin female socket (for USB/serial adaptor) 2 2-way 5.08mm pitch screw terminal blocks [Altronics Cat P2040/P2040A] 1 2.4in or 2.8in ILI9341-based colour LCD touchscreen [SILICON CHIP ONLINE SHOP Cat SC3410] 2 short (~100mm) female-female jumper leads 14 long (~200mm) female-female jumper leads (for LCD screen) 1 1m length of Bell wire, tinned copper wire or light-duty hookup wire (not needed for double-sided PCB) Semiconductors 1 PIC32MX170F256D-I/PT microcontroller, QFP-44, programmed with Micromite V2 firmware (IC1) 1 74LS14 hex Schmitt trigger inverter, DIP-14 (IC2)^ 1 LM3940IT-3.3 3.3V 1A low-dropout regulator, TO-220 (REG1) [Jaycar Cat ZV1565] 1 5mm LED (LED1) ^Not needed with Pololu Capacitors motor drivers 1 47µF 6V tantalum electrolytic         2 47µF 16V aluminium electrolytic 1 100nF MKT or ceramic Resistors (all 1/4W 5%) 1 47kΩ 1 4.7kΩ 1 1kΩ 1 470Ω 1 18Ω Parts list – DIY H-bridge H-bri dge (per module, 2-4 required) 1 double-sided PCB, code 11109192, 54.5 x 23mm 1 5-pin header socket (CON1) 1 4-pin terminal block, or 2 2-pin terminal blocks (CON2) 2 small heatsinks (cut down from Jaycar HH8526) 1 piece of insulating material, 20 x 20mm (eg, presspahn or stiff plastic) 2 M3 x 16mm machine screws, shakeproof washers and nuts Semiconductors 1 74HC08 quad 2-input AND gate, DIP-14 (IC1) 2 BC546 100mA NPN transistors, TO-92 (Q1,Q6) 2 IRF4905 P-channel Mosfets, TO-220 (Q2,Q4) 2 CSD18534KCS N-channel Mosfets, TO-220 (Q3,Q5) [SC4177] 4 1N5819 40V 1A schottky diodes (D1-D4) 4 15V 1W zener diodes (ZD1-ZD4) Capacitors 1 100µF 25V low-ESR electrolytic Resistors (all 1/4W 5%) 2 3.6kΩ 2 2.2kΩ Australia’s electronics magazine 2 1.5kΩ 2 160Ω September 2019  39    Fig.15: to make the pot wipers    continuously variable, prise the lugs holding the rear cover on apart and remove the stoppers on both the pot cover and the internal workings. pin that’s closest to CON5, the ICSP header, while the opposite ends of the pot tracks go to the other two pins. But you need to be careful to connect these two connections with the correct polarity, or else the motor will bump into its end stops the first time it’s powered up. To get this right, disconnect the motor wiring one at a time and briefly power each from a 12V source so that they rotate fully clockwise, then measure the resistance from the wiper to each end. Find the end which gives the highest resistance when fully clockwise, and ensure that this end is wired to the ground pin on CON12a-d. The ground pin is the one centre pin of each header, while +5V is at the right-hand end. Also, make sure that you don’t get the motor wiring mixed up; the motor which is wired to CON12a should be powered from the M1 outputs (CON8a or CON9a) and so on. Wiper motors usually have a switch in the gearbox which need to be bypassed in this application. Wiring for all motors must be isolated from the motors and frames; you should also make necessary arrangements that take into accout that there are several parts which move and could cause chafing later on. The top side of the completed controller PCB with the four Pololu H-Bridge motor controllers in situ, with heatsinks (eg, Jaycar HH8526) attached. Set-up and testing You can now change the jumper leads from the Tx and Rx pins of CON2 to go to CON4 rather than CON3, then power the controller up by placing a shorting block on JP1 and plugging the USB cable into your PC. After the splash screen has been shown and you can see the main screen (shown in Screen2), briefly disconnect each motor from the power supply and apply 12V to Motor 1 should move anti-clockwise about 45°. This command should return it to centre: Screen1: the initial splash screen which appears on the LCD touchscreen when power is first applied, assuming that the Micromite firmware and BASIC code has been loaded onto the PIC32 chip. Screen2: this shows you the current motor positions (POTx) and desired motor positions (MOTx), along with the internal temperature reading. Touch the limit percentage bars to adjust the motor power for each axis. 40 Silicon Chip each motor in each direction. Check that as the motor rotates clockwise, the relevant POTx reading on the screen increases, and as it rotates anti-clockwise, the reading decreases. Check also that the temperature reading is correct. Set the roll, surge and sway limits low, then connect all the motors back to the main power supply and switch it on. The motors should all move towards the centre, then stop. If any of them are acting up, switch the power supply off and check their wiring, especially to CON12a-d. Now open a terminal emulator program and connect to the USB/serial port on your PC at 115,200 baud (or use MMedit chat facility), then type the following sequence and press Enter (you may need to copy and paste this text into some terminal programs for it to work): A<at>~~~Z (That’s a capital A, the at symbol, three tildes, and a capital Z). A~~~~Z  (That’s a capital A, four tildes, and a capital Z). Repeat these commands, moving the <at> (at symbol) to the right, to test the other motors, eg: Australia’s electronics magazine siliconchip.com.au Here’s the electronics “works” – the (commercial) power supply on the left and the H-brdge controller on the right. ing, flying and other simulators: A~<at>~~Z A~~<at>~Z • • • etc. www.x-sim.de www.xsimulator.net http://bffsimulation.com If that all works, then you’re ready to close the terminal emulator, turn up the settings on the touchscreen, fire up your simulator and give it a try! Once you’ve finished testing, it’s up to you whether you want to leave the controller board powered from the 5V USB supply, via JP1, or rig up a 5V regulator to run the controller off the 13.8V motor supply – or via some other arrangement, like a 5V DC regulated plugpack. To see just how expensive commercial equivalents of this project are, check out the following links: Useful links Further information regarding the actual seat development and construction can be viewed on the following link: The following websites are dedicated to simulations which have developed accessible programs to extract the physics data from many supported games, including driv- • • • • • • • www.pagnianimports.com.au https://simxperience.com www.inmotionsimulation.com www.atomicmotionsystems.com www.cxcsimulations.com www.vrx.ca www.xsimulator.net/community/marketplace/ 2dof-3dof-optional-descriptions.81/ Changing the software Screen3: this is the screen which allows you to save or load those presets, depicted as three different types of vehicle. siliconchip.com.au The BASIC code includes two variables called PotLimMax and PotLimMin which allow the motor potentiometers to work at the centre of their movement, taking account of any possible small ‘overrun’ past the +90° and -90° maximum angles. PotLimMax is the required travel angle of rotation of the pots (from 0 to 1), in this case, a full 180°, while PotLimMin is the value at the lowest point of the travel (-90° angle, again from 0 to 1). There are also offset variables (Brk1, Brk2, Brk3 and Brk4) are used to limit or remove any minute motor movements due to pot variation when standing still. These also assist in ‘powering-off’ the motors when movement is not required. You can control the most suitable axis strengths relating to the type of simulation being run, by limiting the PWM pulse width to a percentage of its maximum value, via the touchscreen. These can be saved and reloaded in three SC presets (Screen3). Australia’s electronics magazine September 2019  41 Melbourne Convention & Exhibition Centre 11-12 September 2019 Connect with the Electronics Industry at Electronex Australia’s only dedicated trade event for the electronics industry returns to Melbourne in September. ElectroneX – The Electronics Design and Assembly Expo will be staged from 11-12 September and following sell-out events in previous years at Melbourne Park Function Centre, has moved to the world class Melbourne Convention and Exhibition Centre. This year’s expanded event will see more than 100 companies represented at the Expo with more new product releases than ever before. The SMCBA’s national conference will also be held concurrently with the Expo and will feature leading international industry experts as they present a series of two day workshops to help build the knowledge and skills of local engineers. ElectroneX is a “must-attend” event for decision makers, managers, engineers and industry enthusiasts who are involved in designing or manufacturing products that utilise electronics or work in the electronics service industry. 42 Silicon Chip Australia’s electronics magazine Australian manufacturing companies have moved towards specialised niche manufacturing over the past decade and companies are now sourcing more products and solutions from Australian based suppliers. In addition to featuring a wide range of electronic components, surface mount and inspection equipment together with the latest test and measurement products and other ancillary products and services, companies can also discuss their specific requirements with contract manufacturers that can design and produce turnkey solutions for specific applications. The last Expo in Melbourne in 2017 attracted around 1200 electronics design professionals including electronic and electrical engineers, technicians and management, along with OEM, scientific, medical, IT and communications professionals, defence, government and service technicians. Free seminars A series of free seminars on the latest hot topics will also be held on the show floor in the purpose built seminar theatre and all visitors are welcome siliconchip.com.au to attend. Trade and industry visitors can register for free online at www. electronex.com.au The SMCBA Electronics Design & Manufacture Conference which is held concurrently with the Expo features leading international experts Jasbir Bath from the USA, Martin O’Hara from the UK and Andy Kowalewski to share information critical to the successful design and development of leading-edge electronic products and systems engineering solutions. Visit www.smcba.asn.au/conference for full conference details or contact Andrew Pollock at the SMCBA on 03 9571 2200. SMCBA Conference The 2019 Surface Mount & Circuit Board Association (SMCBA) conference is again being held in conjunction with ElectroneX at the Melbourne Convention and Exhibition Centre. A comprehensive two-day workshop program is being presented by Martin O’Hara from the UK, Jasbir Bath from the USA and Andy Kowalewski. Martin O’Hara is conducting a two day workshop – “New Product Development and Introduction”. This workshop will cover, from start to finish the processes and procedures for new product development and introduction – everything you need to know and implement from product conception to market introduction, to maximise the success of your products. Martin is a Chartered Engineer, Fellow of the Institution of Engineering and from 2013 to 2016 was the National Strategy Manager for the ESPRC. siliconchip.com.au Jasbir Bath, who has over 25 years of experience in research, design, development and implementation in the areas of soldering, surface mount and packaging technologies. is conducting a two day workshop – “Improving Manufacturing Yield and Reliability”. This workshop is being presented in six parts – Part 1: “Design for Manufacturability and Reliability”, Part 2: “Board Pad and Stencil Design, Soldering Materials, Board and Component Surface Finishes and Their Effect on Manufacturing Yield and Reliability”, Part 3: “ Backward and Forward Compatibility Assembly and Reliability, Low Silver and Higher Reliability Lead-Free Solder Alloys Used in Electronics Manufacturing”, Part 4: “Printing and Its Effect on Manufacturing Yield”, Part 5: “Reflow, Wave and Rework Soldering Process Optimization in Electronics Manufacturing” ­and Part 6: “Other DFR Considerations”. With a technical background in avionics, covering HF, VHF and UHF airground-air and radio link communications, radar and navigational aids, and a board designer for 39 years, Andy Kowalewski is conducting a two day workshop – “PCB Design”. This is a comprehensive two-day course covering many of the trade-offs and design that make PCB design ever more difficult. As technology evolves in components, board fabrication and board assembly, competent PCB designers and engineers need to stay in tune with the industry in order to be successful in bringing products to the market on time, on budget and with a minimum of development cost. Australia’s electronics magazine September 2019  43 Stand B10 Way to go, The WAGO Group is an international, standard-setting supplier of electrical interconnection and automation products and interface electronics. The family-run company is the world market leader and inventor of spring pressure connection technology. WAGO has continued to grow since being founded in 1951, with a current worldwide workforce of around 8000 globally and sales of €862 million in 2017. WAGO products are used globally in power and process technology, building automation, machinery and equipment, as well as industrial and transportation applications. They are trusted anywhere electrical conductors must be connected to each other or where complex automation systems must be controlled. Here they have continuously been proven to contribute to safety and the reliable operation of devices and complete installations. The WAGO Group consists of nine international production and main sales locations, 20 additional sales offices and the M&M Software specialist. In addition, there are representatives in over 80 countries, giving the company a strong global presence. WAGO’s new 221 Series COMPACT Splicing Connectors comes in 6mm2 Easier, faster, safer: these three attributes characterize WAGO’s 221 Series Splicing Connectors. WAGO’s 221 Series now offers a model for conductors up to 6mm2. Previously, stranded or fine-stranded conductors up to 4mm2 were connected with WAGO’s 221 Series Splicing Connectors. WAGO-I/O-SYSTEM 750 XTR for Hazardous Areas WAGO’s 750 XTR Series offers solutions for machines and systems with regard to environmental conditions and external interference factors, while providing the highest degree of flexibility. At temperatures from -40°C up to 70°C, vibrations up to 5g, operating altitudes of up to 5000m above sea level or enhanced immunity to electromagnetic interference and other interference as per EN60870-2-1. CLOUD CONNECTIVITY – Your Link to the Digital World Recording, digitizing and linking data profitably – this is the core concept behind Industry 4.0. As the interface between automation and information technology, cloud connectivity meets this challenge. Installed on the WAGO PFC Controllers, machine data can be transferred via MQTT to the cloud, for example, Microsoft Azure, Amazon Web Services, IBM Cloud, SAP Cloud and last but not least WAGO Cloud, where the information can be aggregated and used for analysis. This capability creates true added value for your company – whether for increasing the efficiency of in-house production, implementing energy management or developing additional end-customer services. 44 Silicon Chip Open for your digital future Digitalisation offers companies the great opportunity to shape their future dynamically and successfully. However, the digital transformation also entails many challenges. Networking, analytics, increased productivity and new business models are all challenges that have to be faced on a daily basis. There are no hard-and-fast rules for handling the digital transformation successfully. Therefore, forward-thinking companies need solutions tailored to meet their specific system requirements. Open and Easy Automation with WAGO‘s PFC200 Controller The second generation of WAGO‘s PFC200 Controller is significantly more powerful and has a larger memory. It enables both traditional PLC and open Linux programming in high-level languages. That’s why it’s the first choice for customers from both worlds, making programming #openandeasy. WAGO 221 Sortimo L-Boxx Mini-Splicing Connector Sets up to 6 mm2 The 221 4mm2 and 6mm2 are now available in two different L-Boxx Mini sets. The sets include an assortment of WAGO‘s splicing connectors for different types of wires and a range of cross sections, including the 221 Series. In the Sortimo L-BOXX, the splicing connectors always remain properly sorted, ready and waiting at the right place when you need them. This provides for space-saving and practical storage of both the splicing connectors and the case itself. More power on your PCB WAGO’s line of PCB terminal blocks gives a comprehensive product portfolio that perfectly meets the needs of today’s power electronics. Combining compact design and a high current-carrying capacity with all the advantages of WAGO’s Push-in CAGE CLAMP connection technology, WAGO’s new terminal blocks simplify wiring and maximise PCB design flexibility. Both parallel and perpendicular too WAGO’s power electronics portfolio includes six terminal block families. The PCB terminal blocks accommodate 4mm², 6mm² and 16mm² conductors, are rated up to 1000 V/76A and can be operated via operating tool or lever. They are equipped with Push-in CAGECLAMP® technology for all conductor types, allowing solid and ferruled conductors to be simply pushed into the unit. The new terminal blocks terminate conductors both horizontally and vertically to the PCB. Furthermore, they can be tested both parallel and perpendicular to conductor entry. WAGO Pty Ltd Australia & New Zealand 2 – 4 Overseas Drive, Noble Park VIC 3174 Australia Tel: (03) 8791 6300 Fax: (03) 9701 0177 Email: sales.anz<at>wago.com Web: www.wago.com.au Australia’s electronics magazine siliconchip.com.au STAND B10 MORE POWER ON YOUR PCB PCB TERMINAL BLOCKS FOR POWER ELECTRONICS WAGO’s line of PCB terminal blocks gives a comprehensive product portfolio that perfectly meets the needs of today’s power electronics. Combining compact design and a high current-carrying capacity with all the advantages of WAGO’s Push-in CAGE CLAMP® connection technology, WAGO’s new terminal blocks simplify wiring and maximize PCB design flexibility. WAGO’s power electronics portfolio includes six terminal block families. The PCB terminal blocks accommodate 4 mm², 6 mm² and 16 mm² conductors, are rated up to 1000 V/76 A and can be operated via operating tool or lever. They are equipped with Push-in CAGE CLAMP® technology for all conductor types, allowing solid and ferruled conductors to be simply pushed into the unit. The new terminal blocks terminate conductors both horizontally and vertically to the PCB. Furthermore, they can be tested both parallel and perpendicular to conductor entry. SAVE SPACE ON THE PCB Beyond their nominal cross-section, the PCB terminal blocks may connect solid and fine-stranded conductors up to the next larger cross-section size. This advantage saves space on the PCB and reduces device connection costs. WAGO’s 2624, 2626 and 2636 Series PCB Terminal Blocks are ideal for space-restricted applications. Tool operation is performed parallel to conductor entry so that the clamping points can be easily reached – even if individual components are tightly packaged on the PCB. This makes these new 2624, 2626 and 2636 Series PCB Terminal Blocks ideal for compact device connections and panel feedthrough applications. Advantages: • Comprehensive product range: 0.2 … 25 mm² (24–4 AWG) • Push-in CAGE CLAMP® termination of both solid and ferruled conductors • Wider conductor range and higher current carrying capacity • Conductor connection and mating direction both horizontal and vertical to the PCB • Testing both parallel and perpendicular to conductor entry EASY-TO-USE LEVER WAGO has developed the 2604, 2606 and 2616 Series PCB Terminal Blocks that enable intuitive and tool-free operation via lever. The blocks’ lever is incredibly user-friendly because the respective latch positions (open/closed) can be clearly identified. When the clamping point is closed, the ease of movement becomes a tremendous advantage: the force of the open spring ensures that the lever closes – even at low force. This intellgent design always ensures a secure connection of the clamping point for all types of conductors, and virtually eliminates errors due to misuse. siliconchip.com.au For more information visit: www.wago.com/au/electrical-interconnections/discover-pcb-connection Australia’s electronics magazine September 2019  45 sales.anz<at>wago.com | (03) 8791 6300 | www.wago.com.au WAGO is a registered trademark of WAGO Verwaltungsgesellschaft mbH. LEACH: Your reliable partner for electronic contract manufacturing In China, there are thousands of contract manfacturers providing PCBA/OEM/ ODM services (most of them are in Guangdong province). Because many factories focus on consumer products, they need huge quantities to keep their SMT lines running for 24 hours. The Chinese market has a large demand for consumer products. But the risks are also high: so many companies develop very fast, then disappear suddenly. Regular SILICON CHIP readers would recognise the name “LEACH”, a Shenzen, China-based company who advertise regularly in the magazine. LEACH was founded in 1999. It is not a huge factory but has a total of three SMT lines, two through-hole lines and one box assembly line. Since they focus on industrial and commercial products, they accept any quantity of orders. Their work lines can switch a maximum of 25 types of boards per day. With a stable and capable team of 88 employees, all multi-skilled, LEACH can purchase from global suppliers and deliver to the entire world. LEACH focuses on industrial products and can accept high mix/low volume. They have engineers to help with lay-out/DFM and provide both full-turnkey service as well as partial-turnkey builds. During the past 19 years, LEACH has accumulated knowledge, expertise and experience in providing electronic manufacturing services. From the concept of a new product to the delivery to customers around the globe, LEACH supports you. Australian company’s FAQs: Have a new idea for a new product? LEACH can work with you in the new electronic design. Do you need to identify the right and cost-effective components? LEACH has the knowledge of the best suppliers in China and in Asian countries. Looking for an efficient and reliable manufacturer? LEACH can provide a high-quality product at the right cost. Do you have low volume and high mix of products? LEACH is the partner to be associated with. Do you need to assure that the product is zero defect? LEACH will test every item before shipment. Do you need to provide the required logistics for global distribution? LEACH will take this task for you. Call in and discuss your organisation’s particular requirements with LEACH at ElectroneX 2019. You’ll find LEACH on Stand D16. And if you can’t make it to ElectroneX 2019, you’ll find many of your questions answered on their website: www.leach-pcba.com Mastercut Expand their Stencil range with DEK Vectorguard High Tension Stand A15 Mastercut have expanded their suite of stencil products with the introduction of the new DEK Vectorguard High Tension reusable frame. Until now, the Vectorguard Blue was the most popular frame system as it provided high print performance and fast stencil changeover. The thin shims allow for significantly reduced storage space requirements too. The new High Tension version of the Vectorguard frame utilises the same shims but the foil tension is 45% greater than a standard stencil. This provides a reduction in “rippling” and aids paste release for fine and ultra fine pitch components. Mastercut’s Director of Marketing, Bill Dennis said “the High Tension system has been developed by Assembly Systems (ASM) in response to the market calling for solutions to the challenges of SMT manufacturing, with ever increasing uptake of fine pitch components in PCB design. Initial interest has been strong and we look forward to a solid uptake.” The DEK High Tension frame is backward-compatible with standard shims so the advantages can be applied to existing stencils. Mastercut will display the new High Tension frame alongside other framing options at Electronex 2019. 46 Silicon Chip Australia’s electronics magazine siliconchip.com.au siliconchip.com.au Australia’s electronics magazine September 2019  47 STAND NO: D33 AT Rohde&Schwarz NGL200 Power Supply Series Thanks to their high accuracy and fast load recovery time, the R&S NGL200 power supplies are perfect for challenging applications. Their two-quadrant architecture allows them to function as both a source and a sink to simulate batteries and loads. Their short recovery times enable them to handle fast load changes that occur, for example when mobile communications devices switch from sleep mode to transmit mode. Some of the benefits and key features include fast load regulation, minimum residual ripple and low noise, galvanically isolated and floating channels. With a display resolution of up to 6½ digits when measuring voltage, current and power, the R&S NGL200 power supplies are perfect for characterising devices that have low power consumption in standby mode and high current in full load operation. In many cases, an additional digital multimeter is no longer necessary. The R&S NGL200 power supplies allow for easy operation with their high-resolution touchscreen, colour coding of operating modes, QuickArb function, EasyRamp function and save and recall instrument settings. The R&S NGL200 power supplies are the right choice for challenging applications. They are used in R&D labs and integrated into production test systems. Electrolube on show at ElectroneX (Stand D9) . . . plus a seminar Electrolube, a division of H.K. Wentworth Limited, is a leading manufacturer of specialist chemicals for electronics, automotive and industrial manufacturing. Core product groups include conformal coatings, contact lubricants, thermal management materials, cleaning solutions, encapsulation resins and maintenance and service aids. Electrolube, the global electro-chemicals manufacturer for electronics, automotive and industrial manufacturing, will present a technical seminar at ElectroneX Australia, which takes place on the 11th and 12th September at the Melbourne Convention and Exhibition Centre. The seminar will be presented by Beth Turner MSc, Development Chemist for Electrolube’s Conformal Coatings Division, who will provide a comprehensive overview of next generation conformal coatings for harsh environments as well as a useful insight into coating vs encapsulation. The seminar will focus on protecting electronics from the harshest environments with new generation conformal coatings. Visitors will have a great opportunity to learn about the different types of coatings available, for instance, how to speed up production dramatically with next-generation UV cure products, as well as explore the varying levels of protection that different coatings provide. Beth will also highlight examples of how to select the most suitable product for your application by providing an insight into how Electrolube has provided collaborative solutions for a number of different applications with their global customers. Visitors will also gain a deeper understanding of when it is better to use an encapsulation resin rather than a coating, the difference between these two mediums and learn more about a new generation 2K conformal coating that encom48 Silicon Chip passes the same features as a resin but in a coating format. Please visit www.electrolube.com for more information about Electrolube’s range of specialist electro-chemicals. 10 95 75 25 5 0 Australia’s electronics magazine EL_AUS_Conformal_87x120mm_072019_prepress 29 July 2019 13:01:43 siliconchip.com.au ALL OPTIONS. ONE PRICE. LIMITED TIME. COMPLETE SOLUTIONS. Until 31 December 2019 you can buy high quality Rohde & Schwarz spectrum analyzers, power supplies, power analyzers and oscilloscopes from our Value Instruments range fully optioned with big cost savings. Value Instruments from Rohde & Schwarz are precise, reliable and universal measuring products that are easy to use and combine practical features with excellent measurement characteristics. Designed for users who want high quality products at a good price. More information about our range is available online at: https://www.rohde-schwarz.com/complete-promotion Contact: sales.australia<at>rohde-schwarz.com siliconchip.com.au Silicon Chip full page Value Inst 181x244 New Sep19.indd 1 Australia’s electronics magazine September 2019  49 31/07/2019 12:03:53 PM Altronics Distributors <at> Electronex: you’ll find them on stand D6 New IX Series pushbutton: ultrawaterproof and highly customisable Powertran toroidal transformers Control Devices is the official APEM distributor for Australia and New Zealand and is pleased to promote the new IX Series push button, the new addition to the I series. The IX Series combines the high qualities of the IP and IA series with a backlit switch.The IX series also features a flexible elastomer membrane actuator, with no space between the actuator and Ø12mm compact bushing, guaranteeing an IP69K panel sealing for an ultra-waterproof feature. This provides excellent resistance to frost, sand and other contaminants. The ultra-thin design has a great ergonomic advantage with a tight matrix mounting. It is highly customisable, with a choice from nine different actuator colours, illuminated markings with five different LED colours and many different symbols. Illumination can also be limited to just the symbol, or the entire membrane actuator. IX series is recommended for harsh environments and all key markets of material handling, agriculture machinery, defence and more. Contact the Control Devices sales team at ElectroneX 2019 (stand C6) or call them direct for further information: Unit 17, 69 O’Riordan Street Alexandria NSW 2015 Tel: (02) 9330 1700 Fax: 02 8338 9001 Email: sales<at>controldevices.net Web: www.controldevices.net Altronics offers a range of toroidal transformers which are certified and approved as per AS/NZS61558.2.6 standards. These Toroidal Transformers are available in various voltage and current ratings starting from 30VA to 500VA. New finger touch LED switches The new touch LED switches are offered in stainless steel body with red or green coloured LEDs. The two models will be available in momentary or alternate action. These LED switches are designed for 50 million cycles and are IP68, IP69K rated for industrial applications. These finger touch switches require a mounting hole size of 19mm and have a temperature range of -25 to +55°C. New lead-free touchscreen 100W soldering station The new T 2460A high power, temperature-controlled soldering station with touchscreen will feature on their stand. This soldering station incorporates a special intelligent microchip control design. It has been developed to meet the present and future lead-free soldering needs of the electronic assembly industry and is suitable for work on SMD electronics. The ergonomic handle with a short distance between heating element and tip allows very fast heat up time and quick heat dispersion. The sensor and heat transfer technology employed ensures precise temperature regulation required for making consistent, reliable soldering connections. The temperature is maintained within ±3°C. Have a chat with the Altronics Distributors team on stand D6; or call Altronic Distributors on 1300 780 999; or send an email to sydneywholesale<at>altronics.com.au; or visit their their web site: www.altronics.com.au LAUNCH OF NEW RIGOL 2GHz MSO AT ELECTRONEX 2019 – Stand A1 Emona Instruments will launch the new Rigol MSO8000 series 2GHz oscilloscopes at ElectroneX at stand A1. The MSO8000 series digital oscilloscopes are a highperformance range design based on RIGOL UltraVision II technology and Rigol’s in-house designed PHOENIX chipset. www.emona.com.au Sydney-MelbourneBrisbane-Adelaide-Perth The MSO8000 series offer bandwidth up to 2GHz, 4 channels with 16 digital channels, up to 10GS/s sampling rate, 500Mpts memory depth and a high waveform capture rate of 600,000 waveforms per second. With a 10.1-inch capacitive multi-touch screen, the MSO8000 series also integrates seven independent instruments into one: • • • • • • • digital oscilloscope 16-channel logic analyser spectrum analyser digital voltmeter 6-digit frequency counter and totaliser arbitrary waveform generator (option) protocol analyser (option) The MSO8000 series also support real-time eye diagram measurement and jitter analysis, making the unit suitable for a wide variety of R & D applications. See the MSO8000 DSO – and much more – at the Emona Instruments Stand (A1) at ElectroneX 2019 – or see their website for local contact details. 50 Silicon Chip Australia’s electronics magazine siliconchip.com.au ontrol evices Unit 17, 69 O’Riordan Street ALEXANDRIA NSW 2015 AUSTRALIA Excellence in Engineering T: 02 9330 1700 F: 02 8338 9001 Joins our extensive product range. PRODUCTS Control Devices is pleased to be the newly appointed distributor of Herga Technology for Australia, New Zealand and South-East Asia. Welcoming Herga Technology, the leading UK designer and manufacturer of footswitches, hand controls and sensing solutions for the Medical, Industrial and Commercial markets. Producing durable and ergonomic controls to enhance performance and product yield. The range covers single or multi-pedal controls in ergonomic designs that are available with electrical/electronic, pneumatic, Bluetooth® wireless and USB switching technologies. With customisation options for switch specifications, electrical connections, mechanical fixings, colours and logos, application areas include industrial, business and domestic machinery switching as well as medical grade switching and sensing. FOOTSWITCHES FOR MEDICAL APPLICATIONS Herga consistently provides medical grade footswitches and hand controls that meet customer’s requirements. The products are certified to ISO13485 and approved to IEC 60601 medical standards. Footswitches offers hands-free operation which can lower the risk of infection and contamination in comparison to hand controls. Herga can provide footswitch solutions for efficient hospital bed handling, operating theatres, doctor surgeries or dental chairs. These Footswitches Palm Switches Bellows Air Switches Pressure Switches Vacuum Switches Infra Red Switches Hand controls Micro Switches Bluetooth Devices APPLICATIONS Medical/Dental Industrial Commercial Lifestyle Custom footswitches provide maximum standards of ergonomic comfort and convenience. Contact Control Devices Sales team today for further information on our products. Our Partnered Products Visit us at STAND C6 Melbourne 11-12 Sept 2019 www.controldevices.com.au siliconchip.com.au sales<at>controldevices.net Australia’s electronics magazine September 2019  51 The Micromite Explore-28 The 28-pin Micromite has been used in many of our projects, and with good reason. It is a low-cost, powerful microcontroller which allows you to create advanced devices with minimal effort. Now the Explore-28 will make your life even easier. It’s a small plug-in module with the same powerful PIC plus a USB socket for comms and programming, giving you everything you need to get started with the Micromite in one handy package. By Geoff Graham# T he Micromite is a high-performance 32-bit microcontroller which can be programmed in a friendly BASIC programming language. It has a lot of built-in capabilities including a variety of communications protocols (I2C, SPI, serial etc), the ability to easily interface to many devices (LCD screens, GPS modules, temperature sensors etc). And it’s really easy to learn how to use it, too. To get started with the Micromite, you just need a programmed chip, which you can then plug into a breadboard. This is not hard to do, but there is a bit of fiddling about to be done before you can start programming the chip. Many readers would prefer a pre-assembled module that can be immediately put to use. That is the essence of the Explore-28. You can plug it into a USB port on your laptop and in a few minutes, have a simple program up and running. For readers who have followed the Micromite story, the Explore-28 combines the 28-pin Micromite Mk2 (January 2015; www.siliconchip.com. au/Article/8243) with the Microbridge interface (May 2017; siliconchip.com. au/Article/10648). 52 Silicon Chip Another way to think about it is that it is a bit like the Micromite LCD Backpack V2 (May 2017; siliconchip. com.au/Article/10652) but without the LCD, and in a much smaller package. The whole module is only a little bit larger than a 28-pin DIL IC package but it packs a lot of hardware, including: • A 28-pin Micromite pre-programmed with the latest MMBasic interpreter. • A USB-to-serial interface, which allows you to plug the Explore-28 into your computer and immediately start programming. • A PIC32 programmer, so that you can update the BASIC interpreter whenever a new version is released. • A power supply with a # http://geoffg.net Australia’s electronics magazine 4-16V input range and the ability to supply up to 150mA at 3.3V (plus 5V, when powered from USB) for external circuitry. This means that if you purchase a pre-assembled Explore-28 module, you can immediately start experimenting with it. You do not need to source the microcontroller, program the firmware, setup a breadboard, etc. It is a fully assembled and ready to go package. It is interesting to compare the Explore-28 to the Commodore 64 from 1982, which also came with a built-in BASIC interpreter and was the most popular computer in the 80s. Many millions were sold worldwide, for around US $600 each. The Explore-28 is fifty times faster, with much more memory and costs about US $20. While they clearly have different end uses, this still illustrates how far modern semiconductor technology has progressed. The Explore-28 printed circuit board and concept was developed by two Micromite enthusiasts in New Zealand: Graeme Rixon and Robert Rozee. It can be purchased as a kit of parts from SILICON CHIP, or as a completely assembled module from Graeme’s website siliconchip.com.au – see the last page of this article for details. Graeme Rixon also offers a full construction pack, which you can download from his website. This includes the PCB Gerber files, parts list, firmware etc. So, you can get your own PCBs made and build your Explore-28 modules from scratch if you wish Connections Explore-28 Features • Complete microcontroller module with USB interface and power supply • Programmed in BASIC, with 60KB program space and 50KB RAM for variables • 19 I/O pins with 10 capable of being used as analog inputs • Supports communications protocols including async serial, I2C, SPI and Dallas OneWire • Support for special devices such as temperature sensors, keypads, IR remote controls etc • Full support for touch-sensitive LCD panels up to 3.6in (9.2cm) diagonal • The Explore-28 has the same • ‘form factor’ as the Arduino Nano, • which means that breakout boards • designed for the Nano will suit the Explore-28. But the two are quite different in a programming sense; the Micromite is vastly more powerful and is programmed in BASIC, not C/C++. The pin-out of the Explore-28 is shown in Fig.1. Essentially, it mimics the pins on the 28-pin DIP version of the Micromite, except pin 20 which is not present. The module also includes two extra pins at the bottom, labelled +5V, which can be used to feed power in or out. When the Explore-28 is plugged into a USB port, it will power itself from the USB 5V supply, and that voltage appears on the +5V pins. This is useful if you want to power some other devices from 5V. You can also power the Explore-28 by connecting an external power source to either of the 5V pins. The input can range from 4V to 16V, so for example, you could power the Ex- Embedded controller features such as sleep, control over clock speed and watchdog timer Built-in PIC32 programmer for updating the firmware Runs from 4-16V <at> 50mA Compact size: 40mm long, 19mm wide and 8mm tall (without header pins) plore-28 from a 12V battery. But note that if you are using an external power source, you cannot plug the Explore-28 into your computer’s USB port at the same time. The two power supplies will conflict and possibly damage your USB port or computer. Secondly, if you are powering the Explore-28 from a car battery, you will need to include extra circuitry to protect it from the excessive voltage spikes that can be found in an automotive electrical system. The Micromite chip itself requires a 3.3V supply, and this is provided by the onboard regulator. This voltage is made available on pin 13 so that you can power external components that require 3.3V. Up to 150mA can be drawn from this pin; however, you will need to make sure that this does not cause the regulator to overheat and shut down Fig.1: the Explore-28 has 19 I/O pins with 10 that can be used as analog inputs. Other connections include a 3.3V output, ground and two pins which can be a 5V output or external power input (4-16V). ANA means analog I/O capable, DIG means digital. The other notations refer to the special capabilities of each pin – see the “Micromite User Manual” for a full description. siliconchip.com.au Australia’s electronics magazine (particularly with high input voltages). USB/serial interface The Explore-28 includes a PIC16F1455 microcontroller, which is programmed to act as both a USBto-serial interface and as a PIC32 programmer (for updating the Micromite firmware). This is called the “Microbridge” and when it is acting as a USB-to-serial interface, it creates a virtual serial port on your computer. This acts like a normal serial port, but it works over USB. As mentioned above, we introduced the Microbridge in the May 2017 issue of SILICON CHIP, and it is used in the later versions of the Micromite LCD Backpack (V2 [May 2017; siliconchip.com. au/Article/10652] and V3 [August 2019; siliconchip.com.au/Article/11764]). The Microbridge connects your computer to the Micromite’s serial console. This is the main programming interface to the Micromite and you can use it to set options, enter programs, run them, get feedback from running programs and also receive data. If you’re running Windows, it will automatically create a virtual serial interface when the Explore-28 is plugged into a USB socket on your computer. This appears as a COM port, usually with a high number such as COM5 or COM21. On Windows 7 and earlier versions, a device driver may be required (see siliconchip.com.au/link/aalb), but Windows 8 and 10 already have the driver built in. You can check the COM number that Windows allocated to the Explore-28 by going into Device Manager and looking for a new device listed under Serial Ports, as illustrated in Fig.2. The Linux kernel and MacOS operSeptember 2019  53 An introduction to the Mighty Micromite The Micromite was designed and develped in Australia and is now popular around the world. We have covered the Micromite in many previous articles but in case you haven’t seen those, here is a quick rundown. The Micromite is based on the Microchip PIC32, which is a high-performance 32-bit microcontroller. While this chip as supplied is powerful, it is not that easy to write programs for it (the manuals run to over a thousand pages!) and the standard programming languages used on it are assembler, C or C++. These languages and the programming software are complex and require experience to use properly. For the average hobbyist, the Micromite firmware makes programming much easier. It’s loaded into the flash memory of the PIC32 and turns the chip into a Micromite. The Micromite firmware insulates you from the complexities of the underlying silicon, while still allowing you to use its features. To program the Micromite, you use the BASIC programming language, which is designed to be easy for beginners and allows you to get started almost immediately. The BASIC language The following is an elementary introduction to Micromite programming. We published a comprehensive four-part article series on programming the Micromite in the February, March, May and June 2017 issue (siliconchip. com.au/Series/311). So refer to those articles for more detailed instruction. The Micromite version of BASIC is called MMBasic (short for MicroMite BASIC) which is loosely based on the Microsoft BASIC interpreter that was popular years ago. That it is “interpreted” means that the firmware reads through your program line-by-line, executing each command as it finds them. BASIC (an acronym which stands for Beginner’s All-purpose Symbolic Instruction Code) was initially developed by Dartmouth College in the USA for teaching programming and therefore emphasises ease-of-use. BASIC is also a powerful language, and it became popular in the 80s and 90s with the introduction of small computers such as the Commodore 64, Apple II etc. These days, it is still used in some large commercial data systems (usually running Pick Basic). BASIC program execution starts at the top of the program and continues until it runs off the bottom or hits an END command. Generally, there is one command per line, although you can have more if you wish, each separated by the colon (:) character. A command can be something like PRINT which will output some text to the console, PIN() which will set the state of an output pin, or SERVO which will control a servo motor. Decisions within the program are made using the IF…THEN command. So, for example, your program can include something like: IF t > 30 THEN PRINT “too high” Your program can also run commands in loops. For example: FOR nbr = 1 to 10 PRINT nbr NEXT nbr This will display the numbers from one to ten. To help newcomers to the Micromite and BASIC programming, we have a tutorial titled “Getting Started with the Micromite”. This begins with the basics then takes you through advanced programming, input/output, communications protocols, and much more. It is recommended reading for anyone starting with the Micromite and can be downloaded for free from the SILICON CHIP Shop. Micromite input/output The Micromite is intended to be a controller that can be embedded in something like a burglar alarm, reticulation controller etc. In this type of 54 54  S Silicon Chip role, its ability to use the I/O pins to control external devices is critical. An I/O pin refers to the physical pin on the Micromite chip. On the Explore-28, these are routed to pin headers on the edge of the module, with the same numbering. So, when you refer to a pin number in your program, that is both the physical pin on the chip and the pin header number. In MMBasic, you configure an I/O pin on the chip using the SETPIN command and this defines the pin as a digital input, digital output, analog input etc. For example, if pin 2 on the chip has been defined as an analog input, the function PIN(2) will read the voltage on pin number 2. You could use it like this: PRINT PIN(2) and you would have a simple voltmeter. To read the state of a pin configured as a digital input, you use the same function, but in that case, it will return zero for a low voltage and one for voltage high. You can set the output level of a pin configured as a digital output by assigning a value to PIN(). For example, this will set the output on pin 24 to a logic high (3.3V): PIN(24) = 1 There are many other things that you can do with the Micromite’s I/O pins, including measuring frequency, timing, generating square waves and more. Special device support A great feature of the Micromite is that it has built-in support for many external devices like temperature and humidity sensors, keypads, real-time clocks and servos. For example, using the IR command, you can receive commands from an infrared remote control. This is easy to do, and it adds flair (and utility) to your project when you can control it by pressing a button on a remote control. As another example, you can connect a low-cost ultrasonic distance sensor to the Micromite and with one function, read the distance to an object in centimetres. Measuring temperature and humidity is just as easy; MMBasic will query the sensor for you and return the temperature in degrees Celsius and humidity in %RH. Perhaps the most outstanding feature of the Micromite is its ability to control a touch-sensitive LCD panel. The Micromite can display text and graphics and respond to touch inputs on the panel’s face. We have used this feature in many projects such as the DAB+/FM/AM Tuner (January-March 2019; siliconchip.com.au/Series/330) and the LabQuality GPS Frequency Reference (October & November 2018; siliconchip. com.au/Series/326). Communications protocols There are many modules and chips that you can buy to measure anything from air quality to acceleration. These all send their data via some communication protocol, usually serial, and the Micromite supports the four main protocols that are in use: • Asynchronous serial, which is used by computers, lab equipment and GPS modules. • I2C, which is used by gas sensors, real-time clocks and many other chips. • SPI, which is used by accelerometers, memory chips, electronic compasses etc. • Dallas One-Wire, which is mostly used for temperature sensors. GPS modules are particularly valuable. These days, they are amazingly cheap ($15-35) and they will give you your precise location, altitude, speed, heading and the exact time. Using the Micromite’s serial interface, it is easy to retrieve this information and they open up a world of exciting projects that can be built.v Australia’s Australia’s electronics electronics magazine magazine siliconchip.com.au Fig.2: when the Explore-28 is plugged into a Windows computer, it is allocated a virtual serial port number by the operating system. You can check what COM number was allocated by going into Device Manager and looking for a new device listed under Serial Ports (COM5 in this example). done by pressing ALT-B, and this has the same effect as if the power to the Micromite was cycled. Programming example Fig.3: when you have connected to the virtual serial port created by the Explore-28, you will see the MMBasic command prompt (“>”), as shown here. At this point, you can try out commands, set options, enter programs and run them. ating systems usually do not need any special configuration and, as an example, under Linux Mint, the Explore-28 normally appears as /dev/ttyACM0. Accessing the Micromite console When you plug the Explore-28 into your computer, the LED marked “PWR” (LED1) will illuminate, to show that it is powered. To access the Micromite’s console, you need to run a terminal emulator on your computer. This takes the key presses that you make and sends them down the serial interface to the Micromite, while also displaying any responses from the Micromite. For Windows, you have several choices. We recommend Tera Term (http://tera-term.en.lo4d.com/), but there are many other terminal emulators to choose from, with some specially written for the Micromite (see the panel titled “Micromite resources”). The Micromite’s console defaults to a speed of 38,400 baud, so all you need to do is configure your terminal emulator for the correct COM port number and this baud rate. Then, when you press Enter, you should see the Micromite command prompt (a greater than symbol: “>”), as shown in Fig.3. At this point, you have full control of the Micromite for entering commands, setting options etc. You can experiment by typing “PRINT 1/7” and pressing Enter. The Micromite will return the result of dividing 1 by 7, then display the command prompt again. This is called ‘command mode’ and siliconchip.com.au it allows you to try out most BASIC commands at the command prompt. It is handy for testing commands while you are learning the language. Note that when you type something on the console or the Micromite sends some data to your PC, the LED marked “MODE” (LED2) will briefly flash to indicate that data is being sent over the virtual serial port. The tactile pushbutton near the LEDs (switch S1) is used to put the Microbridge into its programming mode (more about that later). A handy feature of the Microbridge is that you can reset the chip by sending a break signal over the virtual serial interface. In Tera Term, this is We mentioned how easy it is to get started with the Explore-28, so here is a short tutorial to illustrate that point. For a beginner, the best method of entering a program into the Micromite is to use the Micromite’s built-in fullscreen editor. This is fully documented in the Micromite User Manual, but to get started, all you need to know is that the arrow keys on your keyboard will move the cursor around the text and the backspace key will delete the character before the cursor. At the command prompt, type “EDIT” followed by the Enter key. This will take you into the Micromite’s editor. Then, enter this short program: SETPIN 15, DOUT DO PIN(15) = 1 PAUSE 500 PIN(15) = 0 PAUSE 500 LOOP To save this program, press the F1 key or CTRL-Q (which does the same thing). This will return you to the command prompt. Then, to run the program, type “RUN” and press enter. This program toggles the voltage on pin 15 of the Explore-28 from zero to 3.3V and then back again every second, and continues doing it forever. You can test this by probing pin 15 with a voltmeter, and you should see the voltage jumping up and down at 1Hz. While the program is running, you will not see the command prompt in the terminal emulator. This is because the Micromite is now busy, but you can regain control by pressing CTRL-C. This is the break key and it will interrupt any running program and return control to the command prompt, so that you can edit the program or enter other commands. Circuit description The Explore-28 is just a little larger than the original 28-pin Micromite in a standard dual inline plastic (DIP) package. But it has many more features including a USB-to-serial interface, onboard PIC32 programmer and a 3.3V regulator. Australia’s electronics magazine The circuit of the Explore-28 is shown in Fig.4. As you can see, it isn’t terribly complex. It consists of three main components: IC1, the 28pin PIC32 microcontroller (the Micromite); IC2, the PIC16F1455 (Microbridge) which provides the USB interface; and a voltage regulator to provide September 2019  55 the 3.3V supply (REG1). The PIC32 used for the Micromite (IC1) is in a 28-pin surface-mounting package, with most of its pins going directly to the header pins on the edge of the board (CON1-CON3). The 10µF capacitor on pin 20 is critical and must be a high-quality multilayer ceramic type. It is used to stabilise the chip’s internal 1.8V regulator, and if it is missing or the wrong type is used, the Micromite will not work. The only Micromite pins which do not go directly to a corresponding pin on CON1-CON3 are: pin 11, the serial data out line, which goes via a 1.5kΩ resistor in order to protect IC1 if an external device attempts to drive it above +3.3V or below 0V (eg, a raw RS-232 signal); and pin 20 (VCAP), as this micro pin is already connected to the required capacitor. Several of the micro’s pins also connect to the Microbridge (IC2), to allow the Microbridge to reprogram the chip and for its USB/serial function. As mentioned earlier, the Microbridge chip has two functions; it acts as a USB-to-Serial bridge and as a PIC32 programmer. On power-up, it starts in the USBto-serial bridge mode, with the MODE LED (LED2) off, except for flickering when there is serial activity. Serial data is transmitted from pin 6, which connects to the receive data pin (pin 12) on IC1. Similarly, the Micromite’s transmit pin (pin 11) connects to receive (pin 5) on the Microbridge chip. A second 1.5kΩ resistor between the TX pin of IC2 (pin 6) and the RX pin of IC1 (in 12) protects IC2 in case external circuitry tries to send data to the Micromite while the Microbridge is active. A 10kΩ pull-up resistor from 3.3V to pin 11 of IC1 prevents glitches on the serial port when the Micromite is reset. Another 10kΩ pull-up resistor on pin 1 (MCLR) prevents spurious resets of the chip. The tactile switch on pin 4 of IC2 is used to place the Microbridge into its PIC32 programming mode. In this mode, the MODE LED (LED2) lights up, and the Microbridge chip uses pin 7 to reset the PIC32 and pins 2 and 3 to drive its programming interface. In normal operation, these pins are in a high-impedance state, so the corresponding I/O pins on the Micromite can be used for other purposes. The power supply is based on a lowdropout linear regulator (REG1; Microchip MCP1703) with a fixed output of 3.3V. This powers both the Microbridge chip (IC2) and the Micromite (IC1) and as mentioned, is also made available on pin 13 of CON1 for external circuitry to use. The MCP1703 can source up to 250mA, with about 50mA of that being used by the Microbridge and the Micromite. Besides this critical 10µF capacitor described above, there are two 100nF bypass capacitors for the 3.3V supplies of IC1 & IC2, plus 4.7µF input bypassing and output filtering ceramic capacitors for REG1. PIC32 programmer Fig.4: the circuit of the Explore-28 module is elegant in its simplicity. IC1 is the PIC32 which runs MMBasic, IC2 is the Microbridge which provides a USB serial port and the ability to reprogram IC1, and REG1 is a low-dropout regulator which provides both ICs with a 3.3V supply rail, derived from USB 5V or a source of 4-16V DC fed in via CON1 and/or CON2. 56 Silicon Chip Australia’s electronics magazine As mentioned above, the Microbridge chip can act as a PIC32 programmer for loading firmware updates into the Micromite (IC1). You essentially get this feature for free, which is handy, as previously you needed to purchase a separate PIC32 programmer to take advantage of new releases of the Micromite firmware. If you purchased the Explore-28 as a fully assembled module or a kit, both microcontrollers (the PIC32 and PIC16F1455) will be supplied pre-programmed, so this programming feature is only required if you want to update the firmware with a new release. The process of loading new firmware into siliconchip.com.au the Micromite is painless and only takes a minute or two. Start by switching the Microbridge into its programming mode and then, using free software on your laptop, you upload the new firmware via USB to the Microbridge, which in turn programs it into the flash memory of the Micromite. To enter into the programming mode, momentarily press the tactile switch on the Explore-28. The Microbridge chip will then immediately switch to its PIC32 programming mode, and the MODE LED will illuminate to confirm this. If you did not intend to enter this mode, you can revert to the USB-to-serial mode by simply cycling the power. The software you need to reprogram the Micromite is called pic32prog. The Windows version is available from the SILICON CHIP website, while the macOS and Linux versions are available from other sites. The Windows version does not need to be installed; you can copy the executable to a convenient location and start a command window in that folder. New versions of the Micromite firmware can be found at the author’s website, http://geoffg.net/micromite.html (scroll to the bottom of the page). The Micromite firmware download on the SILICON CHIP website is also updated periodically, but there may be a delay between a new release and it appearing on our website. Generally, the firmware is contained in a .zip file, along with the Micromite manuals, so you need to unzip its contents and locate the firmware file (it has a .hex extension). Then, copy this file to the same folder as the pic32prog program. Programming the firmware To program this file into the Micromite chip, run pic32prog with the following arguments: pic32prog -d ascii:comxx yyyy.hex Here, xx is the COM port number and yyyy.hex is the name of the firmware file. The COM port number is the same as that allocated by Windows when the Microbridge was in its USBto-serial converter mode. As an example, if your Microbridge was allocated the virtual serial port of COM23 and the file that you wanted to program was “Micromite_V5.05.09. hex”, the command would be: 58 Silicon Chip Fig.5: the typical output from pic32prog after it has programmed a new version of the MMBasic firmware into the Micromite using the Microbridge. The whole operation is straight forward and takes less than a minute. pic32prog -d ascii:com23 Micromite_V5.05.09.hex Before you do this, make sure that you have closed the terminal emulator that you were previously using to communicate with the Microbridge in its USB-to-serial mode. Not doing this is a common mistake and it will cause pic32prog to abort with an error message, because it cannot open the virtual serial port. When you press enter at the end of this command, pic32prog will upload the hex file to the Microbridge, program it into the PIC32, then read back the programmed data to verify that the programming operation was executed correctly. The whole operation will take less than a minute and sample output of the whole process is shown in Fig.5. After the programming operation, the MODE LED will switch off, the Microbridge will revert to operating as a USB-to-serial converter, and the Micromite will automatically restart with the new firmware. Updating the Micromite’s firmware will reset any options set and completely erase the BASIC program memory. So make sure that you make a copy of the program stored on the Micromite before starting the upgrade. Construction Because the Explore-28 is readily available as an assembled module, we expect that many readers will take Australia’s electronics magazine that option. However, if you decide to assemble your own module, you will find that it is not hard but you will need a steady hand and ideally, some experience soldering surface-mount components, even though the ones used in this project are not that small (at least, by SMD standards). We have covered soldering surface mounted components before and it is nothing to be feared. The secret is to use plenty of flux paste and keep only a small amount of solder on the soldering iron’s tip. The flux makes the solder flow smoothly around the joint while using only a minimal amount of solder means that you will avoid solder bridges and blobs. The PCB used for the Explore-28 is a four-layer board, coded 07108191 and measuring 39 x 18.5mm, and it has components mounted on both sides. The overlay diagrams, Figs.6(a) and (b), show where the components are mounted, along with top and bottom layer tracks. We haven’t shown the two inner layers because that would make the diagrams hard to read. The outer layer tracks shown are used for signal routing, while the two inner layers consist of a ground plane and a power (+3.3V) plane. These cover most of the board and only have holes where vias pass between the top and bottom layers. Other vias are used to connect these siliconchip.com.au CON2/3 (UNDER) 28 CON2 /3 (UNDER) 28 15 5V 15 5V K CON4 IC1 K 1 S1 1 CON1 (UNDER) 14 5V LED2 MODE ACTUAL SIZE 1.5kW 10kW 1.5kW 10W 1 100nF IC2 100nF 28 1 1.5kW 10mF CON2/3 siliconchip.com.au IC1 K S1 CON4 4.7mF 1 REG1 4.7mF 15 5V Fig.6: use these same-size photos and PCB overlay diagrams (top and bottom view) as a guide to assembling the Explore-28. Because the Micromite Explore-28 is so small, we’ve also prepared the twice-life-size diagrams at right to make life a little easier! As mentioned in the text, it’s easiest to populate the bottom side first (with IC2 & REG1) since these components are all similar heights, so the board should still sit relatively flat while you solder the remaining components on the top side. If you’re having trouble getting it to sit flat, try plugging a pair of 15-pin headers into a breadboard and then resting the PCB on top. planes to component pins. While Fig.6 shows where all the components need to be mounted, the silk screen printing on the board will also guide you during assembly. It’s best to solder the SMD components on the bottom side first (the side with IC2 and REG1), then add the components to the top side, and finish with the pin headers. Before soldering IC2, if you haven’t purchased a pre-programmed kit, you need to program it with the Microbridge firmware. This can be downloaded from the SILICON CHIP website or from: http:// geoffg.net/microbridge.html (scroll to the bottom of the page). You will also need a narrow SOIC programming socket to do this, so unless you have one, you’re better off acquiring a programmed chip. You do not need to program the PIC32 microcontroller used for the Micromite, as the Microbridge will do that for you when you have finished construction. Solder IC2 on the bottom side of the board first, taking care that its pin 1 dot is orientated towards the nearby empty square pads, as shown in Fig.6. If you accidentally bridge two pins with solder, clean up the bridge by applying a little flux paste and then some solder wick. Follow with REG1, which can only go in one way around. It’s best to apply a little flux paste to the large pad first, then solder the three smaller pins K 14 5V 10kW (b) CON1 1.5kW 1 LED1 PWR 1 (a) 14 CON1 (UNDER) 5V 2:1 SCALE FOR CLARITY (DOUBLE ACTUAL WIDTH & HEIGHT) 1 1.5k CON1 10k before finishing with the large tab. You may need to turn your iron up to get a good solder joint on the tab. Now add the seven resistors and five capacitors to the bottom side, being careful not get any of the different values mixed up. Flip the board over and then solder the USB socket. Make sure its five signal pins line up correctly with the pads (aided by the two plastic posts going into holes on the board), then solder those signal pins and ensure there are no bridges between them. If there are, apply some flux paste and clean them up using solder wick. Then solder the four large mounting tabs, to hold the socket firmly to the board. With that done, you can continue with soldering IC1; again, watch its orientation – pin 1 goes at the opposite end from the USB socket. Where to buy the Explore-28 • A full kit or major parts from the SILICON CHIP ONLINE SHOP (see siliconchip.com.au/shop) Full Kit: (Cat SC5121) $30.00* or 2 Prog. micros: (Cat SC5120) $20.00* 4-layer PCB only: (Cat SC5115) $7.50* *Inc. GST; P&P: $10.00 PER ORDER • If you’re looking for a pre-assembled module, go to Rictech Ltd (www.rictech.nz/micromite-products) or to https://micromite.org/ Also visit the Rictech website for a downloadable Construction Pack with PCB, firmware etc. Australia’s electronics magazine 1.5k IC2 100nF 10k 1 100nF 28 5V 4.7 F 1.5k 1 1.5k 10 14 10 F REG1 4.7 F CON2/3 15 5V Then fit LED1 & LED2, with their cathodes (generally indicated with a green stripe or dot) towards the “K” shown in Fig.6 (shown on the PCB itself as white squares). But note that while most LEDs have a green dot or stripe to indicate the cathode, we’ve seen LEDs where it indicates the anode. So to be extra safe (and avoid a lot of fiddling rotating of components later), it’s best to probe each end of the LEDs with a multimeter set on diode test mode. When they light up, the red probe is on the anode and the black probe on the cathode. Finish up by soldering pushbutton S1 in place, followed by the three headers, fitted to the underside of the board as shown. Testing To test the completed Explore-28, simply connect it to a USB port on your computer and program the latest firmware into the Micromite as described above (if your Micromite chip wasn’t already programmed). Then check that you can get the MMBasic command prompt via a terminal emulator. If you can, it means that everything is working perfectly. If you do not see the virtual serial port created by the Microbridge on your computer, the first thing to check is that the voltage regulator is producing 3.3V (measure between pins 13 & 8). If this is OK, then the Microbridge September 2019  59 Parts list – Micromite Explore-28 1 four-layer PCB coded 07108191, 39 x 18.5mm 1 15-pin male header, 2.54mm pitch (CON1) 1 6-pin and 8-pin male header, 2.54mm pitch (CON2,CON3) (optional) 1 mini type-B SMD USB socket (CON4) [Altronics P1308, element14 2300434] 1 mini SMD tactile pushbutton switch (S1) [element14 1629616] The Explore-28 is designed to plug into a standard (solderless) breadboard for easy prototyping. Using the preassembled module, you can plug it into a USB port on your laptop and in a few minutes, have a simple program running. chip is probably at fault, with the most likely causes being poor soldering or an incorrectly programmed chip. If you can connect via the USB-toSerial interface but you do not see the Micromite’s prompt, you should check that the Micromite was programmed correctly, that the capacitor on pin 20 is of the correct type and, of course, that your soldering is good. A handy check is the current drawn by the completed module. This is nor- mally about 36mA. You would need to connect an ammeter between a 4-16V DC supply and the bottom row of pins on the board to measure this. If it is closer to 15mA, the Micromite chip is not running correctly, while a current draw of less than 5mA points to a problem with the voltage regulator. So, there you have it. The Explore-28 is an easy to use microcontroller module that you can use as the Semiconductors 1 PIC32MX170F256B-50I/SO microcontroller programmed with MMBasic, SOIC-28 (IC1) 1 PIC16F1455-I/SL microcontroller programmed for Microbridge, SOIC14 (IC2) 1 MCP1703A-3302E/DB low-dropout 3.3V regulator, SOT-223 (REG1) 2 red SMD LEDs, 2012/0805-size (LED1,LED2) Capacitors (all SMD 2012/0805 ceramic) 1 10µF 6.3V X5R 2 4.7µF 16V X5R 2 100nF 50V X7R Resistors (all 1% SMD 2012/0805) 2 10kΩ (Code 103) 4 1.5kΩ (Code 152) 1 10Ω (Code 100) brains of your next project. It is a fun thing to play with and an excellent way of learning to program in the BASIC programming language. SC Micromite Resources Latest firmware versions, manuals and tutorials: .......................................................................................................http://geoffg.net “Getting Started with the Micromite” and “Micromite User Manual”:........................... http://geoffg.net/micromite.html#Downloads The Back Shed forum, where many knowledgeable users can help newcomers:.......www.thebackshed.com/forum/Microcontrollers Microbridge Resources Firmware for the Microbridge (PIC16F1455) in the Explore-28:................................ http://geoffg.net/microbridge.html#Downloads pic32prog, used to program new firmware into the Micromite (Windows):.............. http://geoffg.net/microbridge.html#Downloads P32P, a user-friendly GUI interface for pic32prog.exe (Windows):..... www.thebackshed.com/docregister/ViewDoc.asp?DocID=21 Terminal Emulators Tera Term, the standard terminal emulator used with the Micromite:.................................................... http://tera-term.en.lo4d.com/ GFXterm, a terminal emulator designed specifically for use with the Micromite. It works with the Micromite’s built-in editor and supports a set of graphics extensions:.................... www.thebackshed.com/docregister/ViewDoc.asp?DocID=22 MMEdit, a complete IDE (Integrated Development Environment) specifically designed for the Micromite. It includes advanced features such as colour coded text, formatting, download and run and more:................ www.c-com.com.au/MMedit.htm 60 Silicon Chip Australia’s electronics magazine siliconchip.com.au young maker electronics by On sale 24 August to 23 September, 2019 My first program Teaching kids about robotics and how to code is made easy thanks to these amazing tech toys. Kids will get a thrill in building their robot then control it with simple drag and drop programming blocks (i.e Scratch). No prior coding knowledge required. NOW 129 $ SAVE $20 Codey rocky robot kit Kids can learn coding and AI while they play. 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KJ9033-KJ9042 Planetarium educational kit ONLY ANY 2 FOR $40 JUST 5995 $ Tobbie II robot kit Build-it-yourself hexiped robot with a 360° free-rotation body. Pair it with micro:bit board to create the coolest projects you can program. KR9260 BUNDLE DEAL: Add micro:bit $34.95 & 4 x AAA batteries $2.95 VALUED AT $97.85 BUNDLE DEAL 8495 $ SAVE $12.90 TEACH THEM ABOUT ! H C T A R C S Scratch is free, it is easy to use, and it lets people of all ages quickly design and program their own interactive animations, stories, games, and even program robots built on core computer components such as Arduino or Raspberry Pi. All this without writing a single line of code. Yes! Scratch has a very simple drag and drop graphical user interface, making it the easiest way to get started in the world of computer coding, only without the traditional text line coding. The ability to code computer programs is an important skill in modern education and future industries. 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SAVE $2 MAKER KIT 17-piece KJ9310 WAS $119 NOW $99 SAVE $20 95 SAVE $20 Short Circuits 1 book and project kit 02 T A general purpose stand for any electronics soldering iron. Metal base. Economy TS1502 WAS $9.95 NOW $6.95 SAVE $3 Deluxe TS1507 WAS $16.95 NOW $9.95 SAVE $7 49 95 5 S1 Soldering iron stands 1395 $ steel barrel and orange cool grip impact resistant handle. Fully electrically safety approved. TS1465 FROM ONLY 2995 $ Set of five 115mm cutters and pliers for electronics, hobbies, beading or other crafts. Soft ergonomic grips. TH1812 95 SAVE $8 Mini electric motor experiment kit KJ9032 WAS $19.95 NOW 24 $ 95 SAVE $3 12-in-1 electrical experiment kit KJ8919 WAS $27.95 NOW 2995 $ SAVE $5 Car or boat electronic kit KJ8972 WAS $34.95 on sale 24.8.19 - 23.9.19 63 Micro:bit Playground 3-in-1 Game Game 1: Keep in tune with the “Guess the Beat” game which includes our Micro:Bit (XC4320 $34.95) + speaker (AS3185 $22.95) Teach the little ones with this 3-in-1 project! 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Features A/B/X/Y buttons, Perfect for building a Raspberry Pi based emulator. Includes start, select, and direction controls. Easily access to all ports on your Raspberry Pi, additional USB ports, configurable, USB powered. XC4404 and a handy storage slot for your spare micro SD cards. XC4403 NOW 1495 $ SAVE $4 2 Shaft universal motor / gearbox set Includes main output shaft exiting either side of the gearbox (i.e to drive wheels) and another singleended shaft at 90º to the former. Metal chassis, includes motor. YG2742 WAS $18.95 HALF PRICE! 95 SAVE $5 Worm drive set Contains one worm gear 24mm long x 12mm dia. and one spur gear. YG2736 WAS $9.95 In the Trade? $ SAVE $4 74 0 4 Speed gearboxes Features an all plastic moulded gearbox and motor casing. Includes FA-30 type 3V electric motor, axle with 2 crank arm. 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Set includes 2 x each 50 & 25mm pulleys, 2 x 11mm pulleys, bushings, screws, nuts and 1m of rubber drive band. YG2869 149 $ Raspberry Pi starter kit Just about everything you need to get started with a Raspberry Pi. Includes: Raspberry Pi 3B+, acrylic case, power supply and USB cable, book (Programming the Raspberry Pi: Getting Started with Python), microSD card loaded with NOOBS software, getting started guide. XC9010 on sale 24.8.19 - 23.9.19 65 THE BEST REWARDS & PERKS! Shop In store & online Earn Points For dollars spent Get Rewards eCoupons for future shops in store 1 point = $1 200 points = $10 eCoupon + Perks offers, event invitations, account profile and more... JOIN OUR CLUB TODAY! exclusive CLUB offers: Da Vinci 3D pen Mobile & lightweight. Designed for children. 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LT3067 REG $19.95 CLUB $16.95 35% Assorted boards. HG9990 REG $27.95 CLUB $17.95 Will hold 1kg rolls. TS1504 REG $19.95 CLUB $16.95 20% Pre-wired. Weatherproof. ST0574 REG $12.95 CLUB $9.95 CLUB OFFER SAVE CLUB OFFER SAVE CLUB OFFER SAVE CLUB OFFER SAVE 12/24V battery tester Solar rover kit IP65 sealed ABS enclosure Universal amplifier module 25% 12/24V Slide switch. QP2263 REG $24.95 CLUB $17.95 40% Easy snap together construction. KJ9026 REG $24.95 CLUB $14.95 25% OFF 20% 240(W) x 160(D) x 90(H)mm. ABS material. 1 Channel 3.5W. HB6134 REG $37.95 CLUB $24.95 AA0223 REG $24.95 CLUB $19.95 exclusive club offer your club. your perks! SHORT CIRCUIT PROJECTS* Keep up to date with the latest offers and what’s on! visit www.jaycar.com.au/makerhub *Applies to Vol 2 & 3 project kits & instruction. Books not included. 66 30% click & collect Buy online & collect in store ! 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TS1512 WAS $12.95 6 95 JUST 1 $ 95 FREE BUTANE GAS ea Bar magnets with purchase of TS1111 Valued at $4.95 (NA1020) Educational magnets. Ideal for hobbyists & children to learn more about magnetism. Bar Magnet TH1874 U Shaped Magnet TH1873 NOW Made of lightweight metal and has strong suction. 195mm long. TH1862 Engineers ruler 25cm with scale Includes several charts and diagrams i.e angle gauges, IC pin spacing tables and chip resistor/capacitor package sizes. R-4 gold plated. TH2520 1995 Includes all soldering essentials for various projects. Pack includes 240V 20/130W turbo soldering iron, spare tip, stand, solder, metal solder sucker with spare tip and O-ring. TS1651 WAS $24.95 Metal desolder tool 595 $ $ Soldering starter kit 16 2995 $ ONLY SAVE $5 95 JUST JUST 1995 $ 3 SAVE $3 995 $ JUST 995 $ $ NOW 1495 SAVE $3 NOW ONLY ONLY 26 $ 995 $ • Includes transistor & diode test • 500V, 2000 count • AC voltages up to 750V • DC voltages up to 1000V • DC current up to 10A • Includes test leads QM1500 $ Low cost gas soldering iron Great for soldering, cutting plastic, or heat JUST NOW 1 5. Magnetic project work mat 3. 10W 240VAC soldering station JUST 95 SAVE $10 4. Solder fume extractor • 30W Mains powered • Supplied with 2 x 7mm dia. glue sticks • Spare glue sticks pk6 (TH1991 $3.95) sold separately TH1997 WAS $12.95 19 $ 4 NOW 1. Mini glue gun 2 1995 $ 6-pce insulated electronic screwdriver set • Ergonomic handles with excellent non-slip grips • Fully insulated shafts rated for 1000V • TÜV and GS approved • Storage case included TD2026 ea SAVE $5 FROM Lead-free solder 99.3% Tin / 0.7% copper - lead free. Rosin cored. 200g rolls. 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A great tool for inspecting hard to reach areas. 3" display. • Records to micro SD card. • 5.5mm semi-flexible tube • HD 720P resolution • Drop resistant QC8716 High torque rechargeable lithium-ion screwdriver with bits Ideal for makers, technicians, and other professionals who are assembling or repairing phones, watches, laptops, drones, etc. 150 RPM no load speed. USB rechargeable. TD2510 Due Early September AV equipment JUST 89 $ JUST $ HDMI audio extractor 4-Way HDMI splitter with downscaling Extracts the audio stream from a HDMI signal so you can listen to the audio through your home theatre system, amplifier or active speakers. Outputs: TOSLINK optical, digital coaxial & analogue 3.5mm stereo audio. AC5030 JUST 39 $ Audio mixer with Bluetooth® technology 95 9995 $ Digital to analogue converter with 4-way switcher Compact and rechargeable, ideal for street busking, outdoor parties, etc. . 3.5mm Auxiliary input & output. 6.5mm Microphone input. 1500mAh rechargeable battery. AM4230 4K HDMI Cat5e/6 extender Send UHD 4K signals from a set top box, media player, or other video source to another room up to 50m away over an ethernet Cat6 cable. High-Dynamic-Range (HDR) video support. AC5020 JUST 69 95 Manually switch up to 4 digital audio devices to analogue via TOSLINK RCA or 3.5mm socket. Supports a wide range of audio formats such as PCM, LPCM, DTS, DOLBY-AC3 and THX. AC1723 Bluetooth® 5.0 Transmitter and receiver with optical ONLY 129 $ Multi-directional, transmit or receive. Supports the latest Bluetooth® 5.0 technology. Allows two Bluetooth® devices to be paired at the same time. AA2112 8-Step automatic marine battery charger with dual output Designed to charge and maintain 12V lead-acid batteries, including Wet, MF, VRLA, AGM and Gel, and Calcium batteries from 1.2Ah to 120Ah. IP68 dust and waterproof rated. Mains powered. MB3627 TERMS AND CONDITIONS: REWARDS / CLUB MEMBERS FREE GIFT, % SAVING DEALS, & MEMBERS OFFERS requires ACTIVE Jaycar Rewards / membership at time of purchase. Refer to website for Rewards / membership T&Cs. Page 1: MULTI-BUYS: National Geo Science Kits Deal: 2 for $40 applies to 2 x KJ9033, KJ9034, KJ9035, KJ9036, KJ9037, KJ9038, KJ9039, KJ9040, KJ9041, KJ9042 or combination. BUNDLE DEAL $84.95: 1 x XC4320 Micro:Bit + 1 x KR9260 Tobbie II & 1 x SB2413 Batteries. Page 3: FREE 1 x 12g Lead-free Solder (NS3086 or NS3092 of your choice) with purchase of TS1465 Soldering Iron. Page 4: Club Offer Project Kit: Micro:Bit Playground for $79.95 when purchased as a bundle (1 x XC4320, 1 x WC6032, 1 x WC6010, 1 x PB8819, 1 x YM2758, 1 x AS3185, & 1 x RP7610). Page 5: Club Offer Project Kit: Wi-Fi Rover for $99 when purchased as a bundle (1 x KR3166, 1 x XC4421, 1 x XC4472, 1 x HP0418, 1 x HP0425, 1 x HP0148, 1 x PH9200, & 6 x RC5360). Page 6: Club Offer: Soldering Accessories for $24.95 applies to 1 x TH1850, NS3048, NS3020 & NA1008. Page 7: FREE 1 x Butane Gas (NA1020) with purchase of TS1111 Soldering iron. Club Exclusive Offer: 25% Short Circuits Project applies to Jaycar 100A: Short Circuit Electronics Learning Series - Short Circuits Vol 2 & 3 project kits & Instruction product category. ST RRY McD ona ld’s QUEEN ST AB ELIZ THE ST $ $ Connects a single HDMI source to four HDMI displays and downscales 4K signals to 1080p. Analogue and digital audio output. AC5004 ETH JUST JUST 179 249 95 T IN S KL RAN F Melbourne City 110 Franklin Street Melbourne, VIC 3004 PH: 03 9329 3961 For your nearest store & opening hours: 1800 022 888 www.jaycar.com.au 100 stores & over 130 resellers nationwide Head Office 320 Victoria Road, Rydalmere NSW 2116 Ph: (02) 8832 3100 Fax: (02) 8832 3169 Online Orders www.jaycar.com.au techstore<at>jaycar.com.au Arrival dates of new products in this flyer were confirmed at the time of print but delays sometimes occur. Please ring your local store to check stock details. Occasionally there are discontinued items advertised on a special / lower price in this promotional flyer that has limited to nil stock in certain stores, including Jaycar Authorised Stockist. These stores may not have stock of these items and can not order or transfer stock. Savings off Original RRP. Prices and special offers are valid from catalogue sale 24.8.19 - 23.9.19. The Macintosh Classic II, also called the Performa 200, was released in 1991. With computers of this age, corrosion and time often take their toll. In this case, the ever-present leaking electros had caused some damage. However, Bruce Rayne managed to make this old “classic” run again. I was 10 or 11 years old when I received my first computer. It had an 8-bit, 3.5MHz CPU, 8KB of RAM and used cassette tapes for data storage. After a couple of years, it was replaced with a faster computer and ended up in the bin. What reason could I possibly have to keep it when my new computer was so much faster? Fast forward 35 years where CPU speeds are measured in gigahertz, RAM is measured in gigabytes and hard drives are measured in terabytes, you would think those old computers would be long gone and worthless. But there’s been an incredible nostalgic resurgence in the popularity of these old devices. I saw my exact model of computer sell on eBay for nearly $300 a couple of months ago. You might think that it’s only people my age and older that are collecting vintage computers, but you’d be wrong. I’ve met teenagers who are collecting 25-year-old computers, fascinated by the role these devices played in the evolution of the personal computer. The more memorable and rare computers can sometimes go for quite obscene amounts of money. Apple’s very first computer (the Apple I) is so rare, siliconchip.com.au every single one known to be in existence is recorded in a registry, along with its sale price. In October 2014, one of these old Apples sold for over US$900,000. Not bad for a computer that sold for $666.66 back in 1976. One of the main selling points of any vintage computer is whether it still functions, but many of the internal components have a limited lifespan, so the older the computer, the greater the chance it will have a fault. Among the most troublesome components are electrolytic capacitors. They tend to leak electrolyte onto the PCBs, corroding surrounding components. Even when a working computer has been tucked away in a dry cupboard for years, it’s not uncommon for it to fail when it’s finally pulled out and switched on. But even worse than a leaky capacitor is a leaky backup battery. These were used to store settings and power the clock when the computer was off and can spew out corrosive chemicals if left long enough, sometimes completely destroying the computer from the inside out. This has lead to a niche business of restoring old computers to extend their operational life. The commonly Australia’s electronics magazine used term “recapping” refers to the replacement of old capacitors with new ones. After recapping a few of my own computers, I have recently started offering these services to others. It’s not a very profitable business model but I do get a great deal of joy bringing these old computers back to life. I’m always on the lookout for potential bargains, so when I see a vintage computer for sale as “not working” or “untested” (which means the same thing), I like to keep a close eye on it. If the price is right, I snap it up. The Classic II My most recent purchase was an Apple Macintosh Classic II. For those not familiar with this model, it followed the release of the Macintosh Classic, which was sold in 1990 as a sort of modernised version of the original compact Macintosh. In one of many strange moves by Apple, the Macintosh Classic offered very few improvements over the Macintosh Plus, a model released four years earlier. Although it now had a built-in hard drive and a slightly redesigned case, it had the same four megabyte RAM capacity, the same Motorola 68000 September 2019  69 Above: a close-up of the damage caused by leaky capacitors. Right: this version of the Macintosh Classic II used a 3.6V ½-AA PRAM lithium battery for CMOS backups, which had luckily not leaked. CPU and the same nine-inch monochrome screen. The one thing it had going for it was its low price tag, which made it very popular with schools and home users. As a result, over 1.2 million units were sold, and there are still quite a few Macintosh Classics floating around these days. A year later, Apple released the more powerful Macintosh Classic II, which looked almost identical to the Macintosh Classic but it was more closely based on the Macintosh SE/30, a model released in 1989. The Classic II had a Motorola 68030 CPU running at 16MHz and the RAM was expandable to 10MB. It had one empty slot for a ROM/FPU expansion card, but in a strange twist, Apple never released one! The Classic II was also a winner with the education and home user market, so they are also fairly easy to come by, though finding one that still works can be a challenge. Regardless of how well a computer like this has been treated or stored, chances are it won’t function today without a few repairs. The Classic II motherboard has between 13 and 16 SMD aluminium electrolytic capacitors (depending on the model revision) as well as a ½-AA size 3.6V lithium backup battery. All early compact Macs were held together with Torx screws, and not many people had matching screwdrivers. As a result, very few owners ever opened them up to replace the battery, so they’ve been left there to leak and corrode. The Classic II is comprised of three main internal parts: the cathode ray tube, the power supply board and the 70 Silicon Chip motherboard (referred to by Apple as the analog and logic board respectively). There is also a cooling fan, a 40MB SCSI hard drive and a 1.4MB floppy drive crammed into the case, plus a speaker mounted in the corner. The power supply board provides +5V, +12V and -12V DC outputs and also hosts the controller for the CRT display. Starting the repair I whipped out my trusty Torx driver and removed the four screws holding the back cover in place. Compact Macintosh cases are sometimes a little hard to open and require some gentle persuasion, but this cover came off with little effort. The corrosion from a leaky battery often spreads to the metal chassis in these Macs, but thankfully the chassis of this one looked clean. The next step was to inspect the motherboard, which sits on metal rails, so I unplugged the floppy cable, the hard drive cable and the power connector and that allowed the motherboard to slide right out. To my relief, I saw a completely intact backup battery. No leakage, no visible “battery cancer”. The whole board looked pretty good to the naked eye. It was the original revision of the motherboard, with 13 SMD electrolytic capacitors (eight 10µF 16V, three 47µF 16V and two 1µF 50V), plus a little blue jumper wire snaking its way across the board. This wire might look like a user modification, but it actually came like this from the factory. Later revisions of this model didn’t have the wire, so Apple obviously resolved this design flaw. Australia’s electronics magazine Each of the capacitors needed to be removed and the pads cleaned. Many of the ICs also needed to have their pads cleaned. siliconchip.com.au Some traces had also been damaged by corrosion from the electrolyte. The example shown above was fixed by soldering copper wire from the nearby via to the SMD IC shown below. This was then cleaned with an ultrasonic cleaner. siliconchip.com.au I put the board under the microscope and could immediately see the results of electrolyte leakage from the capacitors. All of the surrounding components had a caked-on yellow crust, something I have seen many times before. The whole board would need a thorough clean. The first thing to do was to get rid of the old capacitors. I use a hot air rework station. Some people like to use solder tweezers, and I’ve even seen someone who likes to cut the tops of the capacitors off, just leaving the pins, then remove them carefully with a regular soldering iron, but I prefer hot air. I use little flat pieces of steel as shields, positioned carefully around the capacitors, to minimise the amount of hot air spilling onto other components. It’s 27 years since this computer was assembled, so I don’t want to push my luck by blasting too much of it with too much hot air. Once the capacitors were off, it revealed large amounts of electrolyte residue around the old pads, but it looked far worse than it was. I started to clean this up by adding a liberal amount of a good quality gel flux, then I added some new solder to the dirty pads and gently moved the flat part of my bevelled soldering iron tip around the pad to melt any old, crusty solder. This is definitely not a job for a conical tip; I prefer fine bevel or small chisel tip. Next, I grabbed some solder wick and gently soaked up all of the solder from the pads. Ever so gently, I rubbed the pads with solder wick to clean off any remaining residue. Finally, I used a cotton bud soaked in isopropyl alcohol to clean off the excess flux, which revealed a sparkling clean pad, ready for the replacement capacitor. There were some ugly looking solder joints on a nearby transistor, so I Australia’s electronics magazine took the opportunity to remove it as well, then cleaned the pads before reattaching it using fresh solder. After removing one of the capacitors, I could see a break in one of the nearby traces. The localised corrosion was so severe, it had eaten right through the solder mask and trace, so that would need to be repaired. It took me a while to remove all 13 capacitors and clean the board up. I was then ready to fit the replacements. For many restoration purists, replacing the electrolytic capacitors with tantalums may seem like vandalism, but I have more interest in preventing future capacitor leakage than I do in preserving the exact look of the original motherboard. I also like to remove the original ½-AA battery holder and replace it with a 20mm button cell holder, as 3V CR2032 batteries are much easier to source, and the computers don’t seem to mind the 0.6V difference between the two battery types. With all thirteen capacitors replaced, I turned my attention to the broken trace. I followed it up to a nearby via, then using a curved surgical scalpel, I gently scraped away the solder mask, revealing fresh copper. I then applied some solder to the copper and soldered some 0.2mm diameter enamelled copper wire to the exposed copper. I then ran the wire around to the other end of the broken trace, which was the pin of a surface mounted plastic-leaded chip carrier (PLCC) IC. I scraped away at the trace coming out from the destination pad (to increase the solder area for the other end of the wire) and trimmed the repair wire to a more suitable length. After repeating the same soldering process to secure the other end of the September 2019  71 wire, I used my multimeter to confirm that the repair had restored continuity. The only thing left was to give the board a good clean. I’ve heard that some people like to clean these old boards with soap and a toothbrush, while others like to resort to the household dishwasher but I wouldn’t recommend either approach. I use an ultrasonic cleaner filled with a diluted detergent designed specifically for PCB cleaning. I dropped the board into the ultrasonic cleaner then gave it about 15 minutes on each side. Ultrasonic cleaners do a great job of cleaning gunk out of tiny crevices, while still being quite gentle. Once the cleaning was complete, I dropped the board into a bath of isopropyl alcohol. This helps to wash away any residual water and detergent, and the low evaporation temperature of the alcohol also speeds up the drying process. I use a small toaster oven set to a very low temperature (around 60-70°C) for drying cleaned boards, leaving the boards in the oven for about 60-90 minutes. Once out of the oven, I gave it a quick inspection while waiting for it to cool. Almost all of the residual electrolyte gunk was now gone, and the trace repair had held together well. Even though the repair looked solid, I still applied several coats of UV-curing solder mask for extra protection. I usually use a UV globe to cure the mask, but it was a sunny day, so I left it in the sun for a few minutes instead. The repaired and cleaned motherboard shown above. Note the CMOS battery and holder were replaced with a much more common CR2032. The power supply board looked fine at a glance, but had large amounts of electrolytic capacitor leakage on the underside (shown below). Testing I put the computer back together, plugged in the mains power cord, flicked the power switch and got nothing, not even a crackle or a pop. It was completely dead. I grabbed my multimeter to see if I was getting any power at all. The external floppy drive connector can be used to check the output voltage, and I read just 2V on the 5V pin, so the power supply board would need some attention. After discharging the EHT, I removed the power supply board and gave it a quick once-over to see if there were any obvious problems. I didn’t find any burn marks, but what I did find was a huge amount of electrolyte leakage near a small cluster of eight electrolytic capacitors. They all needed to be replaced. This is a known failure point for these 72 Silicon Chip Australia’s electronics magazine siliconchip.com.au boards, so I keep a good supply of replacements. I de-soldered the joints for all eight capacitors and pulled them off the board. This revealed the full extent of the leakage, with dirty brown rings of liquid under each capacitor. Cleaning the power supply board is a little trickier than cleaning the motherboard, as it has a small speaker riveted to the surface. Submerging a speaker in an ultrasonic cleaner wouldn’t be the smartest move, so I used a little isopropyl alcohol and a toothbrush to get the worst of the gunk off the board. Once cleaned, I then soldered in the replacement capacitors. Before reassembling the computer for another test, I took a few moments to inspect the solder joints. Some of the components on the power supply board are relatively large and bulky, so the weight can sometimes cause cracks in the joints over time. I found a few ugly looking joints, so I removed the old solder and replaced it with new stuff, just to be thorough. With fingers and toes crossed, I put the Macintosh back together and powered it up. I got the familiar “ding” sound of the Macintosh startup chime. A couple of seconds later I heard more “dings”, meaning I wasn’t quite finished yet. The computer was starting but kept restarting itself in an endless loop. Chances were this was being caused by the voltage being a bit low and I could probably fix this with a minor adjustment. My multimeter showed about 4.5V on the 5V power rail. Thankfully, the power supply board is equipped with a small potentiometer for minor voltage adjustments, so I gave it a twiddle until the voltage read exactly 5.0V. The reboot loop stopped and the Macintosh started booting into an operating system from the 27-year-old, 40-megabyte internal hard drive. A quick glance at the original owner’s files revealed that this computer hadn’t been used in nearly 20 years. As I intended to sell this old Mac, I went ahead with a few other housekeeping tasks, such as replacing one of the cogs in the floppy drive eject mechanism, as this is a well-known weak point. Don’t ask me why, but of the four cogs in the mechanism, one of them changes to the consistency of an aged cheese when it gets old, while the others are unaffected. Even though this one had not yet failed, its disintegration was inevitable, so I saved the future owner from any potential headaches. I also gave the floppy drive heads a good clean, then erased the internal hard The black potentiometer (PP1) on the power supply board provides minor voltage adjustments, and was needed to adjust the 5V rail. The floppy drive eject mechanism in the old Macintosh Classic IIs had a habit of deteriorating, as seen by the yellowed cog at far right. siliconchip.com.au Australia’s electronics magazine drive and installed a “fresh” operating system. Even though a quick block test of the hard drive came up clean, it’s a miracle that this drive still works, and it could fail any day. Thankfully there are modern replacements available, such as the SCSI2SD adapter that allows the old SCSI hard drive to be replaced with a modern micro SD card. Now that the Macintosh Classic II works, what can you do with it? The answer is quite simple: you can do anything you could do with it in 1991. There are a large number of online resources with vintage software that can be run on these old computers: word processors, spreadsheets, graphics, games, music etc. Thousands of old applications that will run beautifully on a computer of this vintage. And that’s precisely what the collectors want to do. They want to relive their past by playing old games from their youth, writing a letter on Microsoft Word version 5.0, or composing a musical masterpiece for playback on the tinny, 55mm speaker. It’s all a bit silly, but it’s also a lot of fun! Extra Links Schematic diagrams (the SE/30 is close in specifications to the Classic II) – siliconchip.com.au/link/aaqd Developer notes – siliconchip.com. au/link/aaqe Service guide – siliconchip.com. au/link/aaqf SC September 2019  73 At last! No more swapping cables every time you want to change audio sources! This high-performance audio switcher can expand the number of inputs on just about any piece of audio equipment with stereo line level inputs. It can be used as a stand-alone device or it can be used to ‘upgrade’ our ultra-low-distortion, low-noise preamplifiers from March 2019 or November/December 2011 to increase the number of available stereo inputs from three to six. I SIX INPUT STEREO AUDIO SELECTOR f you’re one of those people who enjoys listening to music from a variety of sources, you’ll know just how much a pain unplugging and replugging cables can be. For example, you might want to listen to CDs or DVDs one day, an MP3 player another, not forgetting your still-vast vinyl record collection another. And other times there’s the audio from your TV . . . but most of the time it’s a DAB+, FM or AM tuner you want plugged in. That’s five but there are many more. So what to do? Our 2011 and 2019 preamplifiers, for example, can switch between three different stereo sources, using either a remote control or front panel pushbuttons. And while three 74 BY JOHN CLARKE Silicon Chip inputs are enough for many people, inevitably, some people need more! They are very high-performance stereo units, with vanishingly low noise and distortion. They both have remote controlled volume and input switching, while the 2019 update added stereo and bass tone controls. While it is possible to add an external input switcher to expand the number of available inputs (eg, our January 2012 standalone three input switcher), that’s an unsatisfying solution. After all, who wants an extra box and an extra remote control? This project expands the number of stereo inputs on either preamp (or indeed any other preamp or all-in-one) to six, which should satisfy most peoAustralia’s electronics magazine ple. Yes, we know that there will be people who need seven or eight, but you have to stop somewhere! It’s an easy upgrade to either preamp, whether you’ve already built it and you just want to add more inputs, or you’re going to build either one from scratch. Simply build the two new boards, wire them up to the existing preamp main board and reprogram the microcontroller on the preamp. Voila, you have more inputs! You can still use the same remote control to adjust the volume and switch between the six input pairs. So that you can use it with other preamp designs, or other equipment entirely, we have designed it so that siliconchip.com.au it can be used as a standalone unit. All you need to do is build the boards, put them in a box and connect a small 9-15V DC power supply and you have a remote-controlled six input switcher with front panel pushbuttons and LED indicators. You can control it with just about any universal remote. Overall design The Audio Selector consists of two PCBs. The main one has the six stereo inputs, one pair of stereo output sockets and the relays used for switching between the inputs. The control PCB has the six pushbutton switches to select each input, with integral LEDs and mounts on the front panel of the unit. The two PCBs are connected by a 14way ribbon cable with IDC connectors at each end. When used as a standalone unit without the preamplifier, an infrared receiver can be included on the control PCB. The main PCB also has a 5V regulator to power the whole circuit from a 9-15V DC source. When used with the preamplifier, the Audio Selector is connected to the main preamp board via a 10-way ribbon cable with IDC connectors. In this case, the Audio Selector is powered from the preamplifier over this cable. The infrared receiver on the preamplifier is then used to control the Audio Selector as well as adjusting the volume on the preamplifier. This requires revised firmware to be loaded onto the preamp micro. If you have a PIC programmer, you can download this from our website and reprogram the chip yourself. Alternatively, you could merely swap the preamp chip out for one already programmed with the revised firmware. If you haven’t built the preamp yet, Features • • • • • • • • • • Six stereo inputs Negligible noise and distortion Input selection via pushbutton or infrared remote controlled LED indicators to show currently selected channel Remembers currently selected input even when powered off Can be built as a standalone unit or incorporated into one of two high-performance preamplifiers Can be retrofitted to suitable existing preamplifiers No mains wiring required; can run off low voltage DC Easy construction Uses common parts you can use a chip with the revised firmware from the start. Circuit description Fig.1 shows the circuit of the main (switching) board while Fig.2 is the circuit diagram of the front panel control board. Let’s start by looking at the main circuit, Fig.1. It’s based around microcontroller IC1, which drives the DPDT input selection relays (RLY1-RLY6) via NPN transistors Q1-Q6 and monitor the switches and infrared receiver via CON10. When the circuit is powered up, the coil of one of six relays RLY1-RLY6 is energised at any given time. Each relay’s pair of COM terminals is connected to its corresponding pair of RCA input sockets, CON1-CON6. So when its coil is energised, those signals are fed through a pair of 100Ω series resistors and ferrite beads FB1 and FB2 to the output sockets, CON7 and CON8. The series resistors, ferrite bead and 470pF capacitors heavily attenuate any ultrasonic signals which may be picked up by the preamp inputs and wiring. Such signals typically come from elec- tromagnetic emissions from nearby equipment, broadcast radio stations (the wires may act like antennas) etc. We only want to feed audio frequency (20Hz-20kHz) signals to the following equipment. One end of each relay coil is permanently connected to the +5V supply while the other end is connected to ground by one of six NPN transistors, Q1-Q6. Each of these transistors has a 2.2kΩ base current limiting resistor which is driven by one of the digital outputs of IC1; RA2 (pin 1) for Q1, RA3 (pin 2) for Q2 etc. So when one of these outputs goes high, the base-emitter junction of the corresponding transistor is forward-biased, switching on that transistor and pulling current through the connected relay coil, energising it. When that output goes low, the transistor switches off and the connected diode (one of D1-D6) prevents the coil from generating a high-voltage spike as its magnetic field collapses, which could damage the connected transistor. When used as a standalone unit, an external source of DC power is applied to terminal block CON11, and this is Looking at the rear of the input PCB with its six stereo RCA sockets, hiding the low-profile relays behind. At left foreground is the connector which has the cable connecting to the preamp board. siliconchip.com.au Australia’s electronics magazine September 2019  75 Fig.1: the circuit of the main Audio Selector board. Microcontroller IC1 switches on one of the six relays, to connect the appropriate pair of input sockets to the output, using NPN transistors Q1-Q6. It connects to the front panel pushbutton/LED board via CON10. That front panel board also hosts the infrared receiver, if built as a standalone unit. If part of a preamp, the IR receiver is on the preamp board, which is connected via CON9. 76 Silicon Chip Australia’s electronics magazine siliconchip.com.au Fig.2: the circuit of the front panel control board is quite simple, as it mainly hosts pushbuttons S1-S6, which have integral LEDs, plus the infrared receiver and its supply filter, which are only fitted if building the Audio Selector as a standalone unit. Otherwise, these parts will already exist on the preamp board. regulated to 5V by REG1 to power the relays and IC1. Diode D7 provides reverse polarity protection while 100µF capacitors are used for input bypassing and output filtering of REG1. JP1 is fitted in the upper position. When used as part of a preamp, 5V power comes from pins 7 and 8 of CON9, with the ground connection made at pins 9 and 10. In this case, JP1 is fitted in the lower position. IC1 has a 100nF bypass capacitor and 10kΩ reset pull-up resistor to ensure correct operation. Control board circuitry As shown, CON10 on the main board connects to CON12 on the control board (Fig.2), and this allows microcontroller IC1 to detect when one of the front panel pushbuttons is pressed and also illuminate the LED in one of the buttons, to indicate the currently selected input. LED1-LED6 are housed within pushsiliconchip.com.au buttons S1-S6. Their cathodes are joined together and to a 2.2kΩ resistor to ground, setting the maximum LED current to around 0.8mA ([5V - 3.3V] ÷ 2.2kΩ). One LED anode is driven to +5V to light it up and the others are left low at 0V, turning off the other LEDs. This is done via pins 5, 7, 9, 11, 13 & 14 of CON12, which connect back to the same pins on IC1 as are used to drive the relays via the six transistors (see Fig.1). Hence, whenever a relay is activated by that output going high, the corresponding LED on the front panel lights up. The pushbutton switches are connected in a ‘matrix’ manner to pins 3, 4, 6, 8 & 10 of CON12. This reduces the number of pins needed to sense a press of one of the six buttons by one (to five). Pins 3 and 4 of CON12/CON10 connect to the RB3 and RB4 outputs of IC1, while pins 6, 8 and 10 of these connecAustralia’s electronics magazine tors go to the RB5, RB6 and RB7 inputs of IC1. These inputs are typically held at 5V via pull-up currents which are internal to IC1. Switches S1, S3 and S5 have one side connected to the RB4 output, while switches S2, S4 and S6 have one side connected to the RB3 output. The other sides of the switches are monitored by the RB5, RB6 and RB7 inputs. Periodically, outputs RB3 and RB4 are briefly brought low in turn, and if one of the three inputs (RB5, RB6 or RB7) goes low at the same time, that means one of the three switches connected to that output has been pressed. The micro figures out which one has been pressed based on which combination of these five pins is low and switches to the selected input. The current input can also be changed by infrared remote control. Infrared receiver IRD1 is a complete infrared detector and processor; its 5V supply is filtered by a 100Ω resistor and 100µF capacitor. It receives the 38kHz signal from the remote control, amplifies, filters it and demodulates it. The result is a serial data burst at its pin 1 output. This is fed to the RA6 digital input of IC1via pin 12 of CON12. Software within IC1 determines whether the received code is valid and if so, which button on the remote control has been pressed and whether that corresponds to one of the six inputs. If it does, it switches to the new input. Regardless of which method is used to select an input, as well as changing over the relays as needed, IC1 stores the current input selection in its permanent EEPROM memory so that the same input will be selected the next time the unit is powered up. If the Audio Selector circuit is built as part of a preamplifier, IRD1 and its supply filter components are not fitted. The infrared receiver on the preamplifier board is used instead. This controls the volume on the preamplifier directly. If an input change is required, the preamplifier board sends a coded signal over pins 1-6 of CON9. These signals are fed to the RA1, RA0 and RA7 inputs of IC1 (pins 18, 17 & 16). The signals carry serial data indicating which input has been selected. The microcontroller on the preamplifier must be reprogrammed to send these signals, as the earlier designs did not have this capability. Once IC1 receives valid serial data from that miSeptember 2019  77 Parts list - Six Input Audio Selector Main board and Control board 1 double-sided PCB, code 01110191, 165 x 85mm 1 double-sided PCB, code 01110192, 106 x 36mm 6 PCB-mounting DPDT relays with 5V DC coil (RLY1-RLY6) [Altronics S4147] 6 PCB-mounting dual vertical RCA sockets (CON1-CON6) [Altronics P0212] 1 white vertical PCB-mount RCA socket (CON7) [Altronics P0131] 1 red vertical PCB-mount RCA socket (CON8) [Altronics P0132] 2 14-pin PCB-mount vertical IDC headers (CON10,CON12) [Altronics P5014] 6 PCB-mount pushbutton switches with blue LEDs (S1-S6) [Jaycar SP0622, Altronics S1173] 2 ferrite beads (FB1,FB2) [Jaycar LF1250, Altronics L5250A] 1 3-way pin header, 2.54mm spacing (JP1) 1 jumper shunt/shorting block (JP1) 1 18-pin DIL IC socket (for IC1) 4 M3 x 12mm Nylon tapped spacers 4 M3 x 6.3mm Nylon tapped spacers 16 M3 x 6mm panhead machine screws 2 14-pin IDC line sockets [Altronics P5314] 1 350mm length of 14-way ribbon cable If you don’t already have one, you will also need a “Universal” Remote Control (see text) – eg Altronics A012 or Jaycar AR1954 or AR1955 Semiconductors 1 PIC16F88-I/P microcontroller programmed with 0111019A.HEX (IC1) 6 BC337 NPN transistors (Q1-Q6) 6 1N4004 1A diodes (D1-D6) Capacitors 1 100µF 16V PC electrolytic 1 100nF MKT polyester or multi-layer ceramic 2 470pF NP0/C0G ceramic or MKT polyester or MKP polypropylene [eg, element14 Cat 1005988] Resistors (all 0.25W, 1% metal film)          4-band code 5-band code 1 10kΩ brown black orange brown or brown black black red brown 6 2.2kΩ red red red brown or red red black brown brown 12 100Ω brown black brown brown or brown black black black brown Extra parts for standalone version 1 3-pin Infrared receiver; TSOP4138, TSOP4136 or similar (IRD1) 1 7805 5V regulator (REG1) 1 1N4004 1A diode (D7) 3 100µF 16V PC electrolytic capacitors 1 2.2kΩ 0.25W 1% resistor 1 100Ω 0.25W 1% resistor 1 2-way screw terminal, 5.08mm spacing (CON11) 1 M3 x 6mm panhead machine screw and hex nut (for REG1) Extra parts for connecting to preamplifier 1 PIC16F88-I/P microcontroller programmed with 0111111M.HEX* 1 10-pin PCB-mount vertical IDC header (CON9) [Jaycar PP1100, Altronics P5010] 2 10-pin IDC line sockets [Jaycar PS0984, Altronics P5310]** 1 250mm length of 10-way ribbon cable** * replaces IC3 in 2011 preamp or IC5 in 2019 preamp ** not required if already part of pre-existing preamp 78 Silicon Chip Australia’s electronics magazine cro, it switches inputs as required. Construction The components for the circuit shown in Fig.1 are fitted to a doublesided PCB coded 01110191, which measures 165 x 85mm while the separate control section components are mounted on a double-sided PCB coded 01110192, which measures 106 x 36mm. The overlay diagrams for these boards, which indicate where the components go, are shown in Figs.3 & 4. Start by building the main board. Fit the resistors first, where shown. The resistor colour codes are shown in the parts list but it’s best to check the values with a DMM set to measure resistance to make sure they’re going in the right places. Follow with diodes D1 to D6, and install D7 if building the standalone unit. Ensure that their cathode stripes face as shown, then feed resistor lead off-cuts through the ferrite beads and solder them in place. We recommend that IC1 is installed using a socket. Make sure its pin 1 dot/ notch faces toward CON9, as shown. Fit the two 470pF MKT/MKP/ceramic capacitors next. Any of these types can be used, but if you use ceramics, they must use the NP0 or COG dielectrics for excellent low-distortion performance. If building the standalone version, you can now bend REG1’s leads to fit the pads, attach it to the board using the specified machine screw and nut and solder and trim its three leads. Mount the remaining capacitors such as the 100nF MKT polyester or ceramic and the 100µF electrolytic capacitors. Electrolytic capacitors are polarised so the longer positive leads must go through the holes marked “+”. Note that only one 100µF capacitor is needed when the Audio Selector is used as part of a preamplifier. Fit the six transistors next. You may need to gently bend their leads out (eg, using small pliers) to fit the PCB footprints. Ensure the flat sides face as shown. Construction continues with the installation of the 3-way pin header for JP1 and the 10-way and 14-way box headers, CON9 and CON10. These sockets must be installed with their slotted keyways orientated as shown. Remember that you don’t need CON9 for the standalone version, but you do need CON11, so now is a good time siliconchip.com.au Fig.3: follow this diagram and the photo below to build the main Audio Selector PCB. Make sure that the header sockets are correctly orientated, as well as IC1, the diodes and electrolytic capacitors. Note that CON1, D7, the two 100µF capacitors and REG1 are only installed if you are building it as a standalone unit. to fit it. Finally, complete the assembly by installing the six relays, the stereo RCA input sockets and the two vertical RCA output sockets. The red vertical RCA socket goes on the left and the white socket on the right. These colours then match those for the CON1-CON6 stereo sockets. Once you’ve finished soldering the parts to the board, plug the pro- siliconchip.com.au grammed microcontroller (IC1) into its socket, ensuring that it is orientated correctly. Front panel control board assembly There only a few parts on the control board but be careful to install the parts on the correct side of the PCB. The component footprints are screen printed on the side they should be in- Australia’s electronics magazine stalled. Pushbutton switches S1-S6 and IRD1 are on one side (the underside, as shown in Fig.4), and the 14way IDC header CON12, the resistors and 100µF capacitor are on the other (top side). IRD1, the 100µF capacitor and 100Ω resistor are not required when the Audio Selector is part of a preamplifier. Fit the pushbuttons first but note that they must be installed the right September 2019  79 Fig.4: the six pushbutton switches and infrared receiver IRD1 (for the standalone version) are mounted on the back of the pushbutton board (which faces towards the front of the unit when installed) while the header socket, resistors and capacitor go on the top (with CON12’s keyway towards S3 and S4). Make sure that the longer straight lead of each pushbutton goes to the pad marked “A”. way around. These have kinked pins at each corner plus two straight pins for the integral blue LED. The anode pin is the longer of the two, and this must go in the hole marked “A” on the PCB (towards CON12). Once the pins are in, push the buttons all the way down so that they sit flush against the PCB before soldering their leads. IDC header CON12 can then be installed on the other side of the board, with its keyway notch towards the bottom. IRD1, the 100Ω resistor and the 100µF capacitor should now be fitted, if building the standalone version. The 100Ω resistor and 100µF capacitor are mounted on the same side as CON12 while IRD1 is mounted on the pushbutton side, with its lens in line with the switches. The leads are bent at right angles, and it is mounted so that IRD1 is at the same height as the buttons. alone unit, you only need to make the 14-way cable which connects the two boards, shown at the bottom of Fig.5. Otherwise, make both the cables, including the 10-way cable that will connect back to the preamplifier board. If you’re building this unit as an upgrade to an existing preamplifier which already has the three-way input switcher, you should already have those cables. Pin 1 is indicated on each socket by a small triangle moulded into the plastic, while wire 1 in each section of ribbon cable should be red. The red stripe of the cable must go to pin 1. The best way to crimp the IDC connectors onto the cables is by using a dedicated crimping tool such as IDC crimping tool (eg, Altronics T1540). Alternatively, you can crimp them in a vice or using large pliers that have jaw protectors, or a woodworker’s screw-adjust G clamp with the IDC connector sandwiched between two strips of timber. Don’t forget to fit the locking bars to the headers after crimping, to secure the cable in place. Having completed the cables, it’s a good idea to check that they have been correctly terminated. The best way to do this is to plug them into the matching sockets on the PCB assemblies and then check for continuity between the corresponding pins at either end using a multimeter. When complete, plug the 14-way cable into CON10 and CON12. The 10way IDC cable (if used) connects between CON9 of the 6-Input Audio Selector and CON7 on the preamplifier. Now place the shorting block on JP1 in the correct position, ie, to the left if you are building this as part of a preamplifier, or to the right if it is a standalone unit. If upgrading an existing preamp, ensure that its onboard micro has been programmed with the revised firmware, coded 0111111M.HEX, which can be downloaded from the SILICON CHIP website. Initial testing Before programming the remote, it’s worthwhile to power the unit up and check that the pushbutton, relays and Making the cables You need to make the interconnecting cables before you can test the Audio Selector. If you’re building a stand80 Silicon Chip Fig.5: this shows how to make the two ribbon cables. Only the bottom one is required if building the standalone unit. If upgrading an existing preamp which already had a 3-input switcher, you should already have both cables. Australia’s electronics magazine siliconchip.com.au LED indicators work as expected. If you’re building it as a standalone unit, this is easily done by feeding 9-15V DC into CON11. Otherwise, you will need to plug the unit into the preamp board and power it in the usual way. You can run the preamp off an AC plugpack for testing, if you have one, via a rectifier and regulator board (eg, our Universal Regulator from the March 2011 issue; see siliconchip. com.au/Article/930). You can switch to using a mains-based power supply once testing is complete. Apply power and check that one LED lights up and you should hear a relay click on when power is applied. Press all the buttons and verify that you hear a click and that the LED in that button lights up, with all the others off. If you want, you can feed an audio signal into each input in turn and check that it’s only fed through to the output connectors when that input is selected. Setting up the remote control The remote control functions can now be tested using a suitable universal remote, as described below. By default, the Audio Selector expects remote control codes for a Philips TV. If this conflicts with any other equipment in your possession, you can switch it to use SAT1 or SAT2 instead. If you have built the Audio Selector as a standalone unit, all you need to do to change modes is to press and hold S1 on the pushbutton board during power-up to switch to using the SAT1 code, or S2 for SAT2. Pressing and holding S3 at power-up reverts to the default TV mode. It’s a bit more tricky if you’re building this as part of a preamplifier because the preamp board has no way of reading the switch states. So in this case, you have to unplug the 10-way cable from CON7 on the preamp board and then use a femalefemale jumper lead to temporarily short pins 1 and 9. Apply power, wait a few seconds, then switch off, remove the jumper cable and plug the ribbon cable back in. That selects the SAT1 mode. To select SAT2 mode, bridge pins 3 and 9 instead. To go back to the TV code, bridge pins 5 and 9. Pin 1 is the one in the upper righthand corner of CON7, nearest to the microcontroller, while pin 9 is in the siliconchip.com.au upper left-hand corner. Pin 3 is immediately to the left of pin 1 and so on. Programming the remote itself Once you’ve chosen the mode, the correct code must be programmed into the remote control. This involves selecting TV, SAT1 or SAT2 on the remote (to agree with the microcontroller set-up) and then programming in a three or four-digit number to tell the remote control to send the codes that the unit is expecting to receive. Most universal remote controls can be used, such as the Altronics A1012 ($29.95) and the Jaycar AR1955 ($29.95) or AR1954 ($39.95). For the Altronics A1012, use a code of 023 or 089 for TV mode, 242 for SAT1 or 245 for SAT2. Similarly, for the Jaycar remotes, use code 1506 for TV, 0200 for SAT1 or 1100 for SAT2. In the case of other universal remotes, it’s just a matter of testing the various codes until you find one that works. Start with Philips devices as these are the most likely to work. There are usually no more than 15 codes (and usually fewer) listed for each Philips device, so it shouldn’t take long to find the correct one. Note that some codes may only partially work, eg, they might control the volume on the preamplifier but not the input selection. In that case, try a different code. Also, some remotes may only work in one mode (eg, TV but not SAT). Once you have set up the remote control, you can power the unit up and complete the testing process by pressing the buttons 1-6 in sequence and verifying that the corresponding LED lights up and the relays click over. Troubleshooting If you run into any problems, the most likely causes are improperly crimped or wired cables, mixed up or reversed components, bad solder joints or unprogrammed/incorrectly programmed microcontrollers. These problems can all cause similar faults, so if it doesn’t work the first time, go over the boards and compare them to Figs.3 & 4. Ensure that all components have been installed correctly, then carefully inspect the solder joints to make sure you haven’t missed any, you have used sufficient solder and there are no dry joints or solder bridges. Australia’s electronics magazine Presumably, you checked the continuity of your cables earlier, but if not, do so now. It’s common to have problems with an IDC ribbon cable because the crimp has not been done with sufficient force for all the blades to cut through the insulation and make good contact with the copper inside. If the unit responds to the 1, 2, 3, 4, 5 & 6 buttons on the remote but the button switches don’t work, check that the IDC ribbon cable to the pushbutton board has been plugged into the line sockets properly. Similarly, if the preamp remote volume function works but not the remote input selection, check the cable from the preamplifier board to the input selector board. Since the cable from the preamplifier board also supplies power to the other two boards, it’s worthwhile checking that there is 5V between pins 5 & 14 of IC1 on the Audio Selector board. Also, check that JP1 is in the correct position. If everything works except the remote control, check that it has fresh batteries. If it does, most likely it is not programmed for the code that the unit is expecting. Re-check that you have set up the Audio Selector board to the right code, and programmed the remote control with the correct corresponding code. Mounting it in the case If building a standalone unit, you will need to choose a case large enough to mount both boards, ie, at least 200mm wide and 150mm deep. If powering it from a plugpack, fit a chassis-mount concentric DC socket and wire it up to CON11. The 12mm tapped spacers can be used to mount the main board in the bottom of the box, while the 6.3mm tapped spacers areused to mount the front panel board after drilling six 9mm diameter holes spaced 15.1mm apart for S1-S6. Once you’ve made those holes, you can temporarily fit the front panel board and mark out the locations of the four mounting holes, then drill them to 3mm. You may want to use black machine screws to attach the front panel board to the front of the case if using a black case, so they are not so visible, and possibly even use countersink head screws. It would also be a good idea to attach some rubber feet to the bottom of the case. SC September 2019  81 Upgrade & Save Build It Yourself Electronics Centres® HURRY, OUR FIRST STOCKS WILL SELL FAST! Top deals in electronics for September. Ideal surveillance solution for renters! 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Arduino Keypad Plate Perfect for Arduino based access control designs, this handy wallplate has a atmega328p chip and is suitable for use with standard shields. K 9650 » Springvale: 891 Princes Hwy » Airport West: 5 Dromana Ave B 0092 Z 6444 Sale Ends September 30th 2019 SAVE 33% 40 $ ProtoHAT for Raspberry Pi® HAT board with soldermasked 0.1” holes & stackable GPIO header. Pi sold separately. Z 6307 SAVE 15% 10 $ Anderson SBS Mini Connectors Supplied with connector housing & contacts. Genderless design. P 7790 15A P 7794 30A P 7798 45A NEW! 7 $ .95 Phone: 1300 797 007 Fax: 1300 789 777 Mail Orders: mailorder<at>altronics.com.au © Altronics 2019. E&OE. Prices stated herein are only valid until date shown or until stocks run out. Prices include GST and exclude freight and insurance. See latest catalogue for freight rates. SERVICEMAN'S LOG Giving an old companion its voice back I’ve always been interested in loudspeakers. Their electromechanical nature appeals to me, as a good speaker needs to be both mechanically and electrically sound, the two parts working together in harmony. It amazes me that despite modern technology and improved materials, their basic operation hasn’t changed in many decades. Modern speakers tend to be more efficient, and usually offer a wider frequency range in a similar-sized cabinet compared to older speakers. But I don’t think they necessarily sound as good as older models. Of course, this is open to argument. There have been endless flame wars, err, I mean discussions online as to what is the best type of speaker. Some quote specs to prove how much better their speakers are. But like many others, I don’t care about the figures as much as how the speakers actually sound to me. Money for nothing I’ve spent a good deal of time in recording studios and high-end showrooms over the years listening to expensive drivers. They don’t always sound as good to me as the numbers suggest. While it could be that I’m just an audio philistine, I know what I like. Merely throwing money at speakers with fancy-sounding European names doesn’t guarantee pleasing results. I’d also argue that the speaker is merely one of the components in a system; all the components need to be up to scratch. Driving a $5000 set of speakers from a cheap and nasty amplifier (or even an expensive one, if it’s poorly designed) won’t do them any favours. And running a rubbish set of speakers from a $5000 reference amplifier is just a waste of money. The fact is that all speakers are not created equal, and the extensive range of cabinets, enclosure materials, driv86 Silicon Chip er constructions/configurations and crossover designs means there’s a lot of room for experimentation. Anyone who has kept up with hifi magazines will be aware of the trends and fads that have come and gone over the years, with speakers made of everything from concrete tubes to metal drums and even cardboard. I recall back in the 70s, a family friend showing off his expensive (and admittedly cool-looking) electrostatic speakers; the first I’d seen outside of magazines. When he fired them up though, I wasn’t as blown away as I thought I would be. They sounded good, but I reckoned our middle-of-the-road system at home sounded better. And while our speakers didn’t look like a couple of framed antique prints hanging on the wall, at least if I cranked the volume, I could feel the sound as well as hear it. Editor’s note: electrostatic speakers can give excellent mid-high definition but are famously lacking in bass, with some having integrated magnetic woofers to try to overcome this limitation. However, home stereo systems are not the only domain of quality drivers. The live music and sound reinforcement worlds feature some serious, high-wattage hardware. Whether it’s an 18-inch bass driver designed for PA systems or a 10, 12 or 15-inch instrument speaker, the type and quality of driver used will profoundly affect the resulting sound. Australia’s electronics magazine Dave Thompson Items Covered This Month • • • • Guitar speaker re-coning Fixing an inverter arc welder Panasonic AM/FM radio repair Double wall oven repair *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz Let’s say I buy a generic 12-inch, 50W speaker from the local electronics store. It’s likely a lot cheaper than buying a speaker designed specifically for instrument amplification, but it will almost certainly not give me the sound I’m looking for, and given the punishing output of an overdriven guitar amplifier, it may not last very long either. Listen to the music Choosing the right speaker can therefore be a bit of a mission. Only the individual knows what sounds good, and this knowledge is not always transferrable to somebody else. Looking at catalogs doesn’t help much either, with lots of purple prose being used to describe speakers to potential buyers. It’s a bit like trying to describe colour to a blind person; for example, the literature for guitar speakers throws around terms like “crunch”, “throaty”, “warmth”, “vintage”, “punch”, “expressiveness” and “chime”. But what do these terms really mean? Half of them sound more like terms you’d expect to hear when wine tasting, not shopping for a loudspeaker! Most of the musicians I know simply go down to a music shop, plug in their instrument and play various amp and speaker combos until they find one that sounds like what they are after. I’ve only ever purchased one speaker from a catalog, and that was for someone who specifically wanted it to put into an existing cabinet. The siliconchip.com.au result wasn’t to my taste, and certainly didn’t match what I interpreted the catalog’s descriptive terms to mean, but he was rapt with it, which is the key point I guess. This is why musicians become passionate about their gear. We’ve usually spent years getting our sound, and we don’t want to have to go through all that drama again. Besides, this newfangled stuff generally doesn’t sound as good. So losing an amp or speaker can be like losing an old friend. Having gear nicked by some chancer at a gig, or damaged on-stage by a bandmate who has had one too many falling into it can be tough to take. Losing a ‘vintage’ amp or speaker is even worse, as these can literally be irreplaceable. The sounds of silence Recently, one of my speakers failed; an ancient Celestion G12-65 (12-inch, 65W, 8W) used mainly for workshop testing. I’m not sure why it popped, but given it is at least 35 years old it could have just thrown in the towel. It worked the last time I used it, but when I plugged it in the other day to test a valve amplifier I’d repaired, there was nobody home. I first thought I’d messed up the amp repair, but on fursiliconchip.com.au ther testing, I discovered the speaker’s voice coil was open circuit. I was despondent, as this speaker has been with me through thick and thin. While checking online and reeling at today’s prices for a replacement, I came across some Celestion re-coning kits and thought that this was a perfect solution. Back in the day, proper re-coning kits were hard to come by and expensive; now they’re a dime a dozen. At $65 including shipping, it was a lot cheaper than replacing the whole speaker, which all things considered is actually still in pretty good nick, the blown voice coil aside. The rub with replacing a voice coil (pun intended!) is that to get to the coil, everything has to come out of the basket (the metal frame of the speaker). And those parts are generally glued in pretty well. It might be possible to remove the old cone and spider (the flexible, corrugated disc that covers and protects the coil cavity) intact, using a razorblade or similar. But it simply isn’t necessary as there is a new cone, spider and dust-cap (the bit in the centre of most speakers) provided in the kit. I can already hear the purists wailAustralia’s electronics magazine ing about the fact this will no longer be a vintage speaker. But I’m OK with that; I’d rather have a newish working speaker than a dead vintage one cluttering up the workshop. When the kit arrived, I first tested the new voice coil; I didn’t want to go through replacing everything only to fit a dud. The old speaker had a nominal impedance of 8W, and while the replacement coil read only 6.3W on my multimeter, that’s actually correct. A multimeter measures the DC resistance only, not the complex reactance, which depends on frequency. September 2019  87 You probably wouldn’t get a correct impedance measurement for a coil by itself anyway, as there is a mechanical component to the reactance as well as the fact that the coil is inductive. To measure the impedance of a driver, you need to use a specialised tester. Or you can hook up a sinewave signal generator to the input of an amplifier, connect the driver to the amplifier via a high-power fixed value resistor, then measure the varying voltage across the driver. Some basic calculations using Ohm’s Law then give you the impedance at a given frequency. Don’t fear the repair Re-coning is often seen as a complicated process not worth doing, so many people don’t even consider it. But I’ve done it quite a few times over the years and if I can do it successfully, so can anyone. I’m no magician! Just a guy with some tools and a little bit of knowledge, and I’m not afraid to have a go. I started the job at hand by preparing to remove the old cone. The spider and voice coil are connected to the bottom of it, and the leads from the coil are soldered to the terminal on the 88 Silicon Chip basket. So I first had to release those wire connectors. I could have just cut them off, but I wanted to get an idea of their overall length, so I heated and un-wrapped them instead. I then used a hobby knife to cut around the edge of the spider and removed enough of it to allow me to see and mark the voice coil resting depth in the magnet cavity with a sharpie; I might need this approximate measurement later. Next, I cut the cone away as close to the basket as possible, leaving the gasket (the thick mounting material stuck over and around the outside edge of the cone) behind. The whole assembly was then lifted clear, and I noted the state of the voice coil as it exited the magnet cavity; in this case, it appeared undamaged. This may seem an odd thing to do, but it tells me whether I should check the magnet aperture more closely for blobs of melted wire or other debris. With the cone clear, I quickly sealed the open coil cavity using several strips of masking tape. In a workshop like mine, there are metal off-cuts and dust everywhere, no matter how well I clean it. Murphy’s Law dictates that Australia’s electronics magazine some of this will find its way into that gap otherwise. Given the size and strength of the magnets on guitar speakers, which are typically welded or otherwise permanently bonded to the basket, the potential for contamination is high. Removing anything magnetic that gets stuck in there can be very difficult. I know techs who don’t bother with this masking-off ritual, especially if they are going to re-cone the speaker immediately, but I neglected to do this on one of the first speakers I re-coned and some foreign objects got in there. It was a right-royal pain clearing them out. For the sake of a minute or two of time and a few strips of tape, I avoided much potential misery. I proceeded to strip the basket of the remaining gasket, cone and spider material. It depends on how this has been attached as to how much work it will be to remove it. In this case, they used some kind of cement. I used a hobby knife and razor-scraper to very carefully cut the remains as close to the basket rim as I could. The possibility for slipping and carving up one’s own hands at this point is very high, and as I’d done exactly that a few times as a youngster building model aircraft, I was particularly averse to having it happen now. Nothing teaches sensible tool skills better than the memory of a painful injury (and boy, do I have a few of those, as regular readers will know)! Even though I cut very close and removed almost all of the remaining bits, I couldn’t get it all with a knife. While I could possibly have glued the new bits onto this and had no further problems, it only takes a slight amount of asymmetry at the wide edge of the cone to stress it. That can result in the voice coil rubbing on the side of the magnet cavity or non-optimal sound reproduction, even if the voice coil does clear the sides. It is well worth the extra effort to clear the old glue and cone from the basket completely. In such cases, I break out my trusty rotary tool and use it with a brass wire-wheel attachment to clean up the rest. This tool is speedadjustable and perfect for the job, but it does make a real mess, so I made sure to do this job outside (see above on sealing the magnet gap!). A quick brush and vacuum afterwards had the basket completely free of any debris. Compressed air can also siliconchip.com.au be used, but I’m wary of blowing more rubbish about, so prefer the vacuum cleaner option. Before going any further, I checked that the basket was still reasonably flat by sitting it face-down on a saw-bench table. These speakers can get knocked about a lot on tour, and over-worked (and possibly over-enthusiastic) roadies can sometimes distort the basket when securing the driver to a cabinet using power screwdrivers. A twisted basket can result in a trickier set-up during the re-coning process, and baskets that are out-ofround or too far gone usually need to be replaced. This one was still fine, despite its long history. Meet the new cone, same as the old cone Speaker coning kits come in several forms; some are pre-assembled, which means the voice coil, spider and cone are all glued together at the factory. This makes the job considerably easier, as the new assembly can simply be dropped into the basket, aligned and glued down. However, many kits come as separate components, and while this makes things a little trickier, the process is still relatively straightforward. My kit came unassembled. After double-checking there was nothing loose that could foul things up, I removed the masking tape covering the voice coil gap. Despite having taken this measure, I decided to check that the gap was clean by wrapping some double-sided tape onto an old ice-cream stick and inserting it into the coil gap, probing it around inside the cavity to pick up anything that might have gotten in there. The first tape came away slightly grubby, so I repeated the process with fresh tape a couple of times until it came out completely clean. I compared the new voice coil to the old one, making sure they were the same physical size; they were. I positioned the new coil into the gap, using the supplied Mylar shims packed around the inside edge to centre everything properly over the magnet. I then adjusted the coil to sit at roughly the same height as the mark I’d made on the old one; I’d fine-tune it later once the spider and cone had been fitted. I used a spare shim to check there was enough clearance between the outside of the coil and the magnet and siliconchip.com.au ensured the coil’s flat, tab-like connecting leads were positioned directly adjacent to the basket terminals, where they’d eventually be connected. I then dry-fitted the rest of the components; though my kit was unassembled, at least the cone and spider had been pre-cut to the right size. Two small holes for the voice coil connections hadn’t been made in the new cone though, so after referring to the old cone, I used a scriber to punch new holes in the same locations on the new one. Satisfied everything fitted, I glued the spider to the basket using the supplied adhesive, with the voice coil’s tabs protruding through the centre of the spider. After clearing excess glue, I left it overnight to cure. The next morning, I used epoxy resin to ring the centre of the spider, the voice coil former and the rim of the basket. I then set the cone into place and gently twisted it side-to-side to bed it into the glue. I also let this set overnight. The following day, I carefully slid the plastic shims out and gently moved the cone back and forth to check that the voice coil was clear; all was well. After soldering two lengths of the supplied ‘tinsel’ wire to the voice coil tabs, which now sat at the base of the new cone, I fed them through the holes I’d made in the cone and soldered them to the basket terminals. Finally, I centred and glued the dust cap to the cone, using some of the glue to run over the short lengths of exposed tinsel wire. I used the same glue to stick the four-part, hard-cardboard gasket ring around the top edge of the cone, and the job was done. I tested the speaker. It sounds as good to my ears as it ever did. Quite “crunchy”, “throaty” and “punchy” in fact. I’d go as far as maybe even calling it “gravelly”! Inverter welder repair Don’t you hate it when you buy something, check that it works and then put it aside, and when you go to use it again, it doesn’t work at all? Especially if it’s no longer under warranty! Well, that’s almost what happened to B. P., with his wonderful new welder. He managed to get a replacement unit but also got to keep the faulty one. So of course, he had a go at fixing it... I bought my first arc welder some 45 years ago. It was an Abel 110A AC unit Australia’s electronics magazine and over the years, I’ve done a lot of welding with it. It’s massively heavy with wheels and a handle to make moving it easier. The transformer has a copper secondary winding, which was the standard back then, but is unheard of these days. I’ve done very few repairs on this unit during its life but I did replace the electrode holder a long while back and around five years ago, I replaced the old dilapidated welding cables with some 250A cables that were salvaged from a defunct mobile diesel welder. I still have this Abel welder and it still works well after all this time. Around five years ago, I bought a smaller 100A AC arc welder from Aldi when it was on special. This unit is much smaller and considerably lighter than the Abel welder but it still has a transformer, although it has an aluminium secondary. I’ve made a few modifications and improvements to this unit over time and it’s still working well today also. This year, I decided to buy one of the newer models of DC inverter welders. I chose a 250A unit, which was the most powerful that was available at the time. It weighs around 5kg and is smaller than the 100A Aldi unit while delivering 2.5 times the amperage. That just goes to show how fast technology improves. After the welder arrived, I unpacked it and connected the cables and did some test welds. I was impressed with the high current and the ease of striking the arc. I’ve only ever previously used AC arc welders and it’s a lot harder to strike an arc with an AC welder than a DC welder. After the successful test, I put the welder away, as I didn’t have an immediate need to do any welding. Around six months later, I got the welder out to do a small welding job but I was amazed and disappointed to find that it no longer worked. All I got was a tiny spark which looked like it was about 10A worth. I suspect this was from the power source intended to initiate the arc. But where was the main welding current? Fortunately, the welder was still under warranty, being less than 12 months old, so I contacted the seller, who requested a video of the fault, which I supplied. The seller then promptly sent me an identical replacement welder but they didn’t want the old welder back. With the high cost September 2019  89 This photo shows the repaired arc welder PCB, with the problem diode circled. All six diodes were re-soldered. Note the generally poor soldering quality. Many of the SMD pads have lumpy-looking joints, indicating a lack of flux activation. of repairs these days, it must have been cheaper for them to just replace the faulty unit with a new one, rather than having it sent in for inspection and possible repair. As soon as the replacement welder arrived, I tested it and confirmed that it was working correctly and I put it away. Then I contacted the seller again and thanked them for their excellent service and very fast replacement of the defective welder. The repair Now that the original welder was officially scrapped, I could take it apart and have a look at it. It would have voided my warranty but the warranty now applied to the new unit, so there was no reason not to open up this nonworking welder to see if I could fix it. I removed the eight screws securing the top cover, lifted it off and put it aside. I could now see the inner workings, which consisted of a couple of circuit boards and a lot of aluminium heat sinks. It still looked brand new inside, which was not surprising, because it had barely been used. The first thing I did was to remove the main circuit board and inspect the soldering on the back for any faulty joints. On a previous occasion, my gasless MIG welder had developed a fault whereby the wire speed control no longer worked and the wire ran at full speed. It turned out to be noth90 Silicon Chip ing more than dry joints on the PCB, which was an easy fix, so I wondered if a similar fault might be at work here. But the PCB soldering was all good, so I turned my attention to the component side of the board, where I looked for any obvious signs of blown-up components. I found nothing, so I took a closer look with a magnifying glass, but there was still nothing obvious. I was beginning to think that this fault was beyond my ability, due to the obvious complexity of the circuitry involved in the unit, when I noticed something that was not quite right. There were six of what appeared to be surface-mount diodes next to a small daughter-board and the middle diode (D15) on the right-hand side just didn’t look right. This diode was sitting at an angle and one of its legs appeared to be raised slightly above its solder pad. It looked like a manufacturing defect, where the component had not adhered to the PCB and therefore was not soldered properly, but it must have been initially touching the pad for the welder to have worked in the first place. I was sceptical that this could be the fault that had stopped the welder from working, but I also wondered if it might be the culprit. As this was the only obvious thing I could see at this time, I decided to resolder the leg of diode D15 and while I was at it, I also re-soldered both ends Australia’s electronics magazine of all the diodes, as they all looked to be lacking a good amount of solder at their joints. This isn’t the first time I’ve seen something like this (see the photo of the repair). I then connected the welder up again and got out what I needed to do a quick test, just in case it was now working again. I wasn’t really expecting it to work, as I didn’t think that something as simple as this minor manufacturing defect could have caused the failure. However, as I didn’t know just how this circuit worked, it was a possibility. To my astonishment, the welder was now working properly again. I was amazed that just one bad solder joint in this part of the circuit had been the cause of the failure. I almost couldn’t believe that I’d found the fault and fixed it so easily. I’d been expecting to find something major to be wrong with the welder that would have either been impossible to find or impossible to fix. I put the welder back together and put it away. Since then, I’ve used it several times for small welding jobs and it has been working faultlessly. One of the great things I’ve discovered about it is that since it’s so much easier to strike the arc, I can use old welding rods that I’ve had stored for some time. Over time, the flux absorbs moisture, which causes difficulty in striking an arc with an AC welder. But not so with this one! It works with rods that I reckon I’ve had for around 25 years. Anyway, it just goes to show that it’s worth having a look at a faulty device, even if you only have limited experience with repairing these devices, as sometimes the fault is easily found and fixed. Panasonic RF-P50 AM/FM radio fix G. C., of Wellington, New Zealand rescued a Panasonic RF-P50 AM/FM radio from the rubbish bin. As is so often the case in equipment that is about to be discarded, the fault was a simple one, easily fixed by someone with some repair skills... The Panasonic RF-P50 in question is powered by two AA cells and it had a very loud crackle in the audio output when the volume control was operated. Also, the audio would “drop out” entirely at some positions on the volume control, making the set virtually unusable. I thought the fix would be trivial: all I would have to do is dissiliconchip.com.au mantle the plastic case and clean the volume control pot. The previous owner had taken the set to an electronics repair shop (there can’t be many of those left these days, surely) and was told the repair was uneconomic (which it probably was!). The set was given to me and I quickly had the case apart and cleaned the volume control pot with a cotton bud and some isopropyl alcohol. After re-assembly, the set worked fine for a day or two but then the crackle and blank spots progressively returned until again it was unusable. Oh well, perhaps a further clean was required, so I did so again. However, the fault reappeared after each clean and the radio was eventually put aside again as unusable. That was a shame as it worked well, with a clear, undistorted audio output for a period after each clean. Finally, after some time I had a “lightbulb moment”; I thought maybe this perhaps this was the classic case of a DC current flowing through the volume control potentiometer. That would likely be due to a faulty (leaky) series capacitor or, lacking such a capacitor, I could add one into the circuit. On a rainy afternoon and with little else to do, I once again pulled open the Panasonic radio’s case. The set uses a 30-pin Sony CXA1619 FM-AM receiver IC centrally placed on the PCB, so I googled the IC number and studied a number of typical broadcast radio receiver circuits based on that IC, one which showed a volume control connected via capacitors between pin 24 (the detector output) and pin 25 (the AF input). Although the PCB was tightly packed with small components, the volume control arrangement could be seen and the voltage divider circuit easily discerned, but no capacitors were located in this area of the PCB. Maybe I was on the right track after all. I had to figure out how to fit a small capacitor in series with the volume control pot. I thought about cutting the very fine track, which was going to be quite difficult if I was to avoid damaging the PCB. Then I realised that the top end of the voltage divider was connected via a miniature 2.2kW 0.25W series resistor. All that needed to be done was to cut one leg of the resistor, lift that end of the resistor off the board, remove the siliconchip.com.au remainder of the lead from the pad and then solder a capacitor between the pad and the remaining lead on the end of that resistor. And that is what I did. I added a 100nF Mylar capacitor in this fashion, then re-fitted the AA battery to test it out. What a difference it made! Even though the volume control pot had not been cleaned this time, a few operations of the pot cleaned up its operation and it then gave perfect audio output. After re-assembly, this little radio was restored to pride of place in the household. It seems obvious now that it was a design fault all along. One has to wonder how many other examples of this little radio have been tossed into the rubbish bin because of this annoying fault. St George DEO-6 Double Wall Oven repair R. L., of Oatley, NSW knew that he would be on his own when it came to fixing a 25-year-old appliance. He used a methodical approach, and it paid off in the end… Approximately 25 years ago, when we renovated our kitchen, we bought a St George Double Wall oven, with digital control. It performed flawlessly until about two years ago. Since then, occasionally while in use, it would emit a beep and shut down. Resetting the circuit breaker would restore its operation. It would then work perfectly for several months until the same thing would happen again. It got to the point where the fault would occur every other time that we used it. My wife was not happy. As I knew there would be no service support for a 25-year-old oven, I would need to fix it or replace it. The oven was in otherwise perfect condition and to replace it would probably involve modification to the surrounding cupboards, so I decided to try to fix it first. I found a replacement controller on eBay, except that it was for the single oven model. But I decided to buy it and become familiar with the circuit before I disassembled my oven. The module consists of two circuit boards. One is a power supply/relay board, and the other, a display/controller board. From the connection diagram supplied with the oven, I figured out how to connect the purchased module to mains power and the other connections; it turns out that the single oven module is identical to the dual oven version, but with a few parts (eg, relays) missing. I plugged it in and ran through all the functions, and it worked fine. So, the big moment came, and I disassembled my oven, removed the controller connections (about 30 wires) and connected it to my bench set-up. I applied power and went through all the functions; it worked as expected. I decided to heat it up a bit and tried again; it still worked. So, I disconnected the module, got out my magnifying headset and carefully scanned the boards looking for dry joints, as the problem was obviously heat-sensitive. I found a couple of suspect joints on the digital board and re-soldered them, but they were not drastic and unlikely to be the cause of the fault. I then checked the power supply board. All was fine until I got to the filter capacitor joints. They looked very strange. The capacitor looked perfectly OK from the top, but I decided to remove it because of the strange-looking solder joints. And that was it; the 2200µF capacitor had leaked (and probably dried out), but because it had been sealed to the board, no electrolyte had spread out from the base. I checked the other three 1000µF electrolytic filter capacitors in the supply circuit; they looked OK, but I replaced them all, as it was reasonable to expect that they would be on the way out as well. I replaced the capacitors with 105°C-rated units, cleaned up the board, reassembled the module and installed it. The oven now runs like new. I saved us the cost of a new oven and my wife is happy. SC Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column? If so, why not send those stories in to us? We pay for all contributions published but please note that your material must be original. Send your contribution by email to: editor<at>siliconchip.com.au Please be sure to include your full name and address details. Australia’s electronics magazine September 2019  91 Introduction to Programming – Part 2 ˃Cypress’ System on a Chip Analog/digital signals and debugging Our last tutorial on using the Cypress Programmable System on a Chip covered programming and using these fascinating mixed analog/digital devices, but being an introductory article, didn’t go into great detail on how to use the programmable analog features which make them so unique. This followup article describes the more powerful CY8CKIT-059 board and explains how to use its capabilities. By Dennis Smith O ur previous article on using Cypress PSoCs (October 2018; siliconchip.com.au/Article/11269) introduced the Cypress Semiconductor CY8CKIT-049-42XX development code, a 32-bit ARM development platform. We described how to install and use its integrated development environment (IDE), and provided a sample program to read the temperature from an NTC thermistor and display it on an LCD screen. This article is based on the more powerful CY8CKIT-059 board, with attached Serial Wire Debug adaptor (SWD) and programmer, shown above. Incidentally, the included SWD adaptor and programmer can also be used with the 049-42XX boards. The main product page for the CY8CKIT-059-5LP development board, which contains links to extensive documentation and the relevant downloads, is at: siliconchip.com.au/link/ aaqn You may need to create a free Cypress account to download the files. The development board is available in Australia for just over $20 (at the time of writing) from element14, Mouser, RS Australia etc. The integrated development environment (IDE), called PSoC Creator, complete with compiler and device specific libraries is available to download for free from the product page above. The CY8CKIT-059-5LP board is 92 Silicon Chip designed around the CY8C5888LTILP097 chip (see www.cypress.com/ part/cy8c5888lti-lp097) which is available in 68-pin QFN or 100-pin TQFP packages (both surface-mounting). It contains an ARM Cortex-M3 32-bit CPU running at up to 80MHz, 256KB of flash memory and 64KB of SRAM; which makes it quite powerful as microcontrollers go. You can download the chip’s Product Overview document, which lists all of its important features, at: www. cypress.com/file/140796/ The chip also includes a coprocessor, called the Digital Filter Block (DFB), which is a 24-bit digital signal processor (DSP). A datasheet on this co-processor can be found at: www. cypress.com/file/315811/ The DFB is useful for certain tasks like matrix/vector multiplication or analog signal processing. Performing these jobs using the DFB frees up the main CPU for other tasks. It also includes programmable analog and digital components, such as ADCs, DACs, timers/PWM inputs, serial communication etc. CY8CKIT-059 Features 32-bit ARM microcontroller with 256KB flash and 64KB SRAM 24-channel direct memory access (DMA) controller Capacitive touch sensing Programmable analog blocks, including: • one 8- to 20-bit delta-sigma analog-to-digital converter (ADC) • two 12-bit successive approximation (SAR) ADCs • analog multiplexers, which can make the ADCs multi-channel capable • four 8-bit DACs • four comparators • four op amps • four programmable analog blocks (continuous time or switched capacitor) Programmable digital blocks: • four timers/counters/PWM (pulse width modulators) • 24 universal digital blocks (UDB), which include registers and an arithmetic logic unit (ALU) • Up to 72 input/output pins • On-chip JTAG/debugging • 1.2(1.7)-5.5V supply voltage Australia’s electronics magazine siliconchip.com.au A removable USB-to-serial and Serial Wire Debug adaptor is included in the kit. Once you have finished your project, the adapter can be snapped off and used as a general-purpose USB/ serial adaptor or as a Serial Wire Debug adaptor for any of the PSoC family boards. The adaptor can also be used as a USB to general-purpose I/O (GPIO) device. Becoming adept at programming PSoCs As with other micros, there’s a bit of a learning curve. The curve might be somewhat steeper with a PSoC than, say, an Arduino, but its ultimate capabilities are far greater. It has a 32-bit CPU rather than 8-bit, and much more memory, but is actually cheaper than most Arduino modules. Most importantly and uniquely, though, it has the configurable analog blocks which give you far greater flexibility and power when it comes to signal processing. Probably the biggest disadvantage of the PSoC compared to other 8-bit and 32-bit micros is that its extra capabilities translate into somewhat higher power requirements. You are also effectively stuck using the Creator IDE for programming PSoC boards; while it's possible to build the project yourself, it's impractical. It's important to note that since the community is smaller, fewer libraries are available for these devices compared to Arduino. Although, given the dodginess of some of the Arduino libraries we’ve come across, sometimes having to write your own code may be a blessing in disguise… to your “C:\Users\<USERNAME>\ Documents\PSoC Creator” folder. They can be placed in other folders if you want, but for this article, we’ll assume you’ve used this default location. Now plug the board into a USB 2.0 port on your PC. An orange LED on the USB-to-serial adaptor indicates that power is present, while a flashing blue LED indicates that all is well. Now unplug the board and plug it back in again, but this time, holding down the button at the rear of the board while you plug in. The blue light should now flash at a faster rate, indicating that the board is now in bootloader mode. With the 049-42XX board described in the previous article, the bootloader was the only way to load programs into the chip. This method still works with the CY8CKIT-059 board, but with this board, you can load your program straight into the board without having to enter bootloader mode. Preparing our first example We’ve provided two example projects this time, both included in the free download (ZIP package) on the Silicon Chip website. We’ll start with the “AnalogDebugExample” project first. Navigate to the “AnalogDebugExample.cydsn” folder and double click on “AnalogDebugExample.cyprj”. This will open PSoC Creator 4.2 IDE and load the project files automatically. Otherwise, you can open the IDE, click “Open Existing Project” from the Start page and navigate to the project folder. You should now see the block diagram shown in Fig.1. If it is not visible, double click on the “TopDesign. cysch” tab at the top of the left panel. Now click on the “Connections” tab at the bottom, and you should see the wiring diagram shown in Fig.2. This just provides a guide for how to configure the hardware and is not required when you make your own projects. You can also view what pins are actively being used on the main IC by going to the Pins item under Design Wide Resources in the left sidebar of the IDE. You should see the same diagram shown in Fig.3. Connect two pushbutton switches to your board, as Fig.2. You can wire the components directly to the board, or if you solder header strips to the development board, you can plug it into a breadboard and then connect the switches that way. But if you are planning to snap off the USB-to-serial adaptor board later, don’t solder terminal strips on just yet. Building and uploading To build the project before programming the hardware, click on the build icon in the tools bar just above the Workspace Explorer window (you can also just press CTRL+F5). If all is well, Using PSoC Creator If you need a refresher on using the software, refer to the previous article (October 2018) on how to get started with Cypress PSoC, including downloading and installing the PSoC Creator IDE. Note that the IDE only supports Windows PCs (7-10). If you already have the IDE installed, you only need to download the “CY8CKIT-059 Kit Only” file from: siliconchip.com.au/link/aaqn Otherwise, you can download the “CY8CKIT-059 Kit Setup” file below it, which gives you the above files as well as the IDE. With the IDE installed, download the project files for this article fromsiliconchip.com.au and unzip the files siliconchip.com.au Fig.1: block diagram of the first example program as shown in PSoC Creator. This program uses an Arbitrary Waveform Generator (WaveDAC8) to generate a tune that is played by pressing SW_1, and have its pitch/tempo varied via SW_2. Australia’s electronics magazine September 2019  93 Fig.2: wiring diagram for the first example program. Note the circuit diagram and the breadboard layout which show how to connect an LM380 audio amplifier and speaker to the CY8CKIT-059 board. you will see output similar to the text below in the Output Window: ------- Build Started: 06/18/2018 14:06:49 Project: AnalogDebug, Configuration: ARM GCC 5.4-2016-q2-update Debug ------Flash used: 6086 of 262144 bytes (2.3%). SRAM used: 2849 of 65536 bytes (4.3%). Stack: 2048 bytes. Heap: 128 bytes. ------- Build Succeeded: 06/18/2018 14:07:18 ------- Fig.3: the active pins of the main IC used in the “Analog Debug” example program. You can view this by clicking on the “Pins” item under “Design Wide Resources” in the left sidebar of the IDE. 94 Silicon Chip Australia’s electronics magazine If you get an error message in the Output Window about missing binaries for the ARM GCC and MDK toolchain, this is because the project is set for a ‘debug’ build and the default toolchain in the build settings is incorrect. To fix this, go to Project → Build Settings in the toolbar. In the Build Settings sub-menu, the second entry “Toolchain” should be set to “ARM GCC 5.4-2016-q2-update” or similar instead of the default “ARM MDK Generic”. Or it might be due to not having the correct binaries for the 059 board. Just having the 042 kit files from the previous article is not enough to successfully build this project. siliconchip.com.au After this, the project should build without any errors, but you might get two warnings about asynchronous paths which you can safely ignore. Unlike the PSoC 049-42XX boards, it is not necessary to press a button on the board before programming. If programming is successful, the log will show a message similar to the one below: Fig.4: a breakpoint (indicated in red) can be set by either clicking to the left of the line-number, or right-clicking the line and selecting “Insert Breakpoint”. Breakpoints determine when to temporarily stop code execution during debugging. ------- Rebuild Succeeded: 06/22/2018 12:45:59 ------Programming device 'PSoC 5LP CY8C5888LT*-LP097' with file 'K:\ARM Development\ Cypress PSoC\Active Projects\ AnalogDebugExample\ AnalogDebug.cydsn\CortexM3\ ARM_MDK_Generic\Debug\ AnalogDebug.hex'. Device ID Check Erasing... Programming of Flash Starting... Protecting... Verify Checksum... Finished Programming Device ‘PSoC 5LP CY8C5888LT*LP097’ was successfully programmed at 06/22/2018 12:46:09. If the chip is programmed successfully, and you have a suitable audio amplifier connected, the opening theme from “The Godfather” will play each time you press SW_1. Pressing SW_2 changes the pitch and tempo while playing a piano scale. The music is created using the built-in arbitrary waveform generator (discussed later). Interactive debugging One of the problems with many microcontroller development systems, including the popular Arduino environment, is that they don’t give you an easy way to debug your program. What do you do if you write some code, upload it to the board, and it doesn’t do what you expected? You generally end up having to add lots of print statements throughout your code, so you can watch the serial console to find out what’s going wrong. That can be time consuming. Wouldn’t it be handy if you could step through each line of your code and check the value returned by a function or from a calculation, while also being able to see the value of each currently active variable? While this is theoretically possible with an Arduino, it is not easy to orsiliconchip.com.au Connection diagram for the PSoC CY8CKIT-059 board. Source and prototyping guide: www.cypress.com/file/157971/download Australia’s electronics magazine September 2019  95 Fig.5: when debugging, the current point of execution is indicated in yellow. If you click the tab at the bottom left called “Locals”, you should be shown the current values of all variables that are currently ‘in scope’. You can also set a “Watchpoint” via right-clicking the variable, which means that the value of that variable will always be displayed when ‘visible’. ganise. But PSoC Creator has in-built debugging. It does this via the 0595LP’s USB-to-serial adaptor which contains its own 32-bit ARM processor. It receives commands from the IDE and communicates with the 059-5LP’s (or 049-42XX) CPU to execute code one line at a time. Since the IDE has access to the source code of your program (including all the library code written by Cypress and others), it is possible to step through each line of code with a press of a key. Using the example project, we can step through the code and see what is happening at each point. It helps to tell the IDE how far through the program we want to go before debugging should start. To do this, we set a ‘breakpoint’. Fig.4 shows what the IDE looks like when we set a breakpoint at the first statement in the code, as indicated by the red blob to the left of the “CyGlobalIntEnable” statement. To set a breakpoint, click in the shaded vertical area to the left of line numbering, or right-click the line you 96 Silicon Chip want to break at, and select “Insert Breakpoint”. Click again on the red circle to remove the breakpoint. Breakpoints can be set on any line. Once you have a breakpoint set, click on the “Debug” drop-down menu and select “debug” or press F5. The IDE will compile the code and program the 059-5LP. It will then begin execution of the code and stop at the first breakpoint it detects. The yellow highlighting shown in Fig.5 indicates where the program execution is currently up to. Now when you click on the Debug drop-down menu, you will see some additional menu items. The new menu items show which function keys you can use to step through the code; for example, F10 will execute the current statement and then step to the next one, F11 is similar but will step into the function itself when relevant. Try pressing F10, then F11 while the “DAC_Start();” statement is highlighted. This will move the debugger to inside the scope of that function which is located in the file DAC.c. Australia’s electronics magazine So if you want to find out what happens within a function that’s called on the currently highlighted line, press F11. If you are only interested in what the function returns, press F10. To see the value of a variable (eg, Button_1_Pressed), hover the mouse cursor over that variable and a popup window will display details of the variable and its contents. Note, however, that the variable must be ‘in scope’, that is, local (or ‘visible’) to the function currently being executed. By right-clicking on the variable, a popup window appears that allows a “Watchpoint” to be created, which means that the IDE will always show the value of that variable whenever it is in-scope. Arbitrary Waveform Generation (WaveDAC8) The above example program uses the Arbitrary Waveform Generator (WaveDAC8) component to play music. This component has an analog output which can provide sine, square, triangle and sawtooth waveforms. It siliconchip.com.au also has the facility for the user to draw their own waveform. You can double-click on the WaveDAC8 component to change its parameters and hear the difference; for example, you can change the waveform shape, and that will affect the timbre of the sound it produces. The test waveforms are shown in Fig.6. Once you’ve wired up the circuit as described earlier, and programmed the chip, pressing pushbutton SW_1 plays a theme song, while pressing SW_2 plays a musical scale, first with the “DAC” object, then in reverse with “DAC_1”, which are both WaveDAC8 components. This demonstrates the use of different waveforms, but the second DAC could also be used for multi-channel playback. The “Voice_Write()” function modifies the contents of a CPU register which enables one DAC while disabling the other. To play the music, I’ve created an array of values which represent the frequency of each note in the tune. These are passed (one at a time) to the “PlayNote()” function, which alters the clock frequency driving each WaveDAC8 unit, to produce a different output frequency. The values stored approximate the frequencies of the notes on a piano. To create a different song, make a new array using TheGodFather[] as a template and following the comments in the code. There are ways to turn audio files, like mp3s, into arrays of bytes which can then be used with this program. Of course, you wouldn’t easily be able to fit more than snippets into program memory. By duplicating the “Volume” control component (a Programmable Gain Amplifier) and the output potentio- Fig.7: The “Analog_Alarm” program alters the behaviour of an LED depending on the input voltage from PIN_1 using the chip’s in-built configure hardware. meter, you can turn this project into a stereo synthesiser. With a little extra programming you could also control the gain of the PGA(s) with the software to set the volume. A second example If you wish to learn more about the Analog components built into the Cypress CY8CKIT-059-5LP, here is a second sample project. It is called “Analog_Alarm” and is included in the download package for this article. Open it up in the IDE, as you did with the previous project. You can see the block diagram for this program in Fig.7. It uses two 8-bit voltage DACs, a voltage reference, three analog comparators, an XOR gate, a 4-input analog multiplexer, a lookup table and three PWM units to produce a voltage alarm. The input voltage comes from the wiper of a potentiometer (variable resistor) connected to input port P3[0]. Depending on the position of the potentiometer, it will drive the onboard LED as follows: 1. For any voltage below 1V, the onboard LED is off. 2. Between 1-2V, the LED pulsates. 3. Between 2-4V, the LED flashes at 100Hz. 4. Above 4V, the LED remains continuously lit. These voltage ranges can easily be changed in the code. You can replace the potentiometer with a voltage source (0-5V only), and you have a voltage monitor facility. More example projects Cypress code Examples: siliconchip. com.au/link/aarf 100 Projects in 100 Days: siliconchip. com.au/link/aarg CY8CKIT-059 driving a VGA monitor: siliconchip.com.au/link/aarh Open FPGA tools: github.com/ azonenberg/openfpga CNC wood router using a 059-5LP: github.com/holla2040/hyatt Cypress buyout Fig.6: the two waveforms used for DAC (left) and DAC_1 (right) shown in Fig.1. siliconchip.com.au Australia’s electronics magazine Recently Cypress Semiconductors was acquired by Infineon for approximately €9B. The acquisition seems to be primarily for Cypress’ automotive electronics, but their microcontrollers like the CY8CKIT-059 shown in this article are likely to continue being developed and sold. SC September 2019  97 PRODUCT SHOWCASE Dual-coloured – all in one bright LED fitting Making sure your switch panel project is highly visible and stands out from the others have now been made easier with LED Autolamps’ most recent new product, the SO58RGM. This lamp typically comes standard with a dual-colored red and green LEDs within a single compact unit, owing to its origins from LED Autolamps’ equivalent automotive-styled range. The SO58RGM includes two super-bright LEDs that are housed inside a specially designed and enhanced lens. This combination creates a bright, wide viewing angle of light instantly alerting operators. The standout features for this lamp is its separately wired circuits for each color as well, independent earthing wires making them ideal for 2-way rotary switches. The SO58RGM utilizes a surface-mounted fitting method, most commonly used in the automotive industry but unique to panel switch lights. These lamps will offer flexibility and ease of installation not seen within this industry. Installation merely requires fixing the bracket to the fitting surface and then clipping the lens in place, cleverly hiding the screws and creating a tidy, professional finish. Harsh operational environments demand a stand out performer and rest assured the SO58RGM is up to the task. Polycarbonate plastics have been used for the lens, ideal for strength, durability and UV resistance, as well as an ABS base to finish the build. They also have been vibration tested and are certified to rigorous IP67 standards for dust and water ingress. LED Autolamps’ renowned quality manufacturing will ensure an extended operational life, and with 30,000 hours LED lifespan these lamps will give you years of trouble-free service. They’re ideal for internal or external control panels, vehicle dashboards, machinery; or any indicator, signal and warning applications. They are supplied in a single poly bag and offer a 3-year peace-of-mind warranty. Available to order diContact: rectly from LED AutolLED Autolamps amps, designers and 42 Enterprise Drive Bundoora Vic 3083 manufacturers of highTel: (03) 9466 7075 quality LEDs for autoWeb: www.ledautolamps.com motive lighting. Wagner Electronics’ new Accento tube Amplifier has Bluetooth! In what might seem to some to be a strange mix of old and new technologies, the new Accento-Dynamica hybrid amplifier from Wagner Electronics has a pair of 6F2 valves, attractively illuminated by blue LEDs, along with (on top of the chassis) a whip antenna to receive Bluetooth signals. The preamplifier is solid state. The Accento is a German-designed hifi mini-amp with a high quality sound for a low price that is ideal for running modern, good quality, compact speakers. With compact dimensions and of course great sound, the unit has two RCA inputs for tuner, CD or media player. The Bluetooth V4.2 signal reception (with external antenna) as well as the built-in USB audio player (supports MP3, WAV, APE, FLAC with play/pause/fast forward/rewind) for modern connectivity and playback. It features a 12W+12W output (into four ohms) with less than 0.1% THD <at> 12W and a 20Hz-20kHz frequency re- sponse (±2dB). The 230V power supply is not switch-mode like most designs these days but linear. The rear panel sports connectors for speakers, headphones and even a subwoofer output while the top panel (front) has USB input (with pushbutton track selection), level (volume) control and inContact: put selector switch. Wagner Electronics Size is 235 x 155 x 84-90 Parramatta Rd, Summer Hill 2130 110mm. It is priced Tel: [Sydney] (02) 9797 9866 at $259 (inc GST) – Web: www.wagneronline.com.au Cat no ADHA24BT. Get your hands on user-programmable hearing aids – without setting foot inside a clinic! You’re not likely to wear your hearing aids much if you’re unhappy with the programming. But it can take frustrating repeat trips to the audiologist to get things sounding just right. So Blamey Saunders puts the power in your hands. Blamey Saunders hearing aids work with an app called IHearYou® that lets you control your settings from your smartphone, tablet or Windows computer. It’s easy. And there’s no need to visit a clinic for the initial set up. Have your hearing aids home delivered and ready to go, preset based on your results from their 98 Silicon Chip Australia’s electronics magazine free online hearing test. Find out if Blamey Saunders’ user-programmable hearing aids will work for you—take the free online test at blameysaunders.com.au/spt It’s quick and clinically validated. Contact: BlameySaunders 364 Albert St, East Melbourne Vic 3002 Tel: 1300 443 279 Web: www.blameysaunders.com.au siliconchip.com.au Silicon Chip--mouser-widest-selection-205x275.pdf 1 30/7/2019 3:55 PM C M Y CM MY CY CMY K siliconchip.com.au Australia’s electronics magazine September 2019  99 Do you ride a pushbike in the dark? You need our new ULTRABRITE LED PUSHBIKE LIGHT This tiny (22 x 12mm) circuit board is a high-efficiency LED driver that delivers a constant 1A or 2.2A. You can use it with a 12V white LED array to make a (very!) bright bicycle light, a torch or another light source. It can be powered from a lithium-ion or LiPo battery pack but there are other options. It also has brightness control and a flashing function. It’s a very compact and modern design, for advanced constructors. Design by Daniel Doyle Words by Nicholas Vinen T here are plenty of bicycle lights and LED torches on or wherever you need a bright light but don’t have ready the market, but there are certain advantages to build- access to mains power. The driver board is tiny, so it can be tucked away just about anywhere. Add a LED and a bating your own. For a start, you get to choose the battery, so you could use tery, and away you go. It has a flashing mode and two reduced brightness options a high-capacity rechargeable lithium-ion or LiPo battery that would last for many hours of use. These are not terribly ex- that you can use for longer battery life. You can also build a higher-power version of the circuit to suit more powerpensive, and can last for many years if treated well. ful LEDs. You also get to choose the SWITCH S1 INDUCTOR L1 It’s a generally useful deLED(s), so you can use a real+ vice. It’s also a good way to ly efficient one for maximum + learn about switchmode powbattery life and brightness. iL PATH 1 er supplies and LED driving. And you can also tailor And while it’s designed to the optics to suit your needs. VIN C1 VOUT LOAD D1 PATH 2 drive LEDs, it isn’t necessarYou can build it with a tight, ily limited to only doing that. bright beam or a wider beam With a few small changes, this to improve your visibility to board can be used as a conobjects not directly in front of you. Fig.1: the general configuration of a step-down switching stant current source for a vaYou don’t necessarily have DC/DC converter, also known as a ‘buck’ converter. When S1 riety of applications. to use this driver board for a is on, current flows through it and inductor L1 to the load, bike light or torch. It could charging up both capacitor C1 and L1’s magnetic field. When S1 Operating principle This LED driver is a “buck” be used for caravan lighting, switches off, the magnetic field starts to collapse, which forces current to continue to flow. This must come from ground, via step-down DC/DC converter to light the bed of a ute or the D1, which along with the charge in C1, causes the load voltage with current regulation. It efcargo area of a van, in a shed, to drop slowly until S1 switches on again. 100 Silicon Chip Australia’s electronics magazine siliconchip.com.au ficiently reduces the 15-21V battery supply voltage down to around 12V, as required by the LED array. The LED voltage is not regulated directly; rather, the circuit attempts to maintain 1A through the LED array, at whatever voltage is required, from virtually nothing up to the full input voltage. Fig.1 shows the basic configuration of a buck regulator. Switch S1 is electronically toggled on and off rapidly to control the current through inductor L1. When S1 is on, the current flowing through L1 increases at a rate determined by its inductance and the voltage across it. Some of this current may flow through the load while the rest charges up capacitor C1. L1’s magnetic field also charges up as the current flows. When S1 switches off, the magnetic field starts to collapse and this forces current to continue to flow into the load and C1, although at a reducing rate. Since current can no longer flow through S1, it must instead come from circuit ground and through diode D1, effectively flowing in a loop through D1, L1 and C1/the load, back to ground. It is the energy stored in the magnetic field which makes this an efficient circuit, as the voltage drop across L1 is not dissipated as heat; most of that energy is stored while S1 is switched on, and recovered when it switches off. By controlling the duty cycle of S1, we can control the current through L1 and thus the average voltage across C1. Circuit description Fig.2 shows the LED driver circuit, including the internal details of the LM3409MY controller. In this case, the switch shown in Fig.1 is actually a Mosfet (Q1). You should be able to see all the other components from Fig.1 in this circuit, with the addition of a 0.22Ω currentsense resistor between the supply bypass capacitors and the source of Q1. Q1 is a P-channel Mosfet which means that the controller IC can switch it on hard, by pulling its gate down to 0V, without needing a boosted gate supply rail. That means if the battery is almost fully discharged, the highest possible LED brightness can still be maintained, as there will be a minimal voltage drop in the circuit (around 0.25V, mostly Features & specifications • Can power a 12V LED array from a 5S (18.5V) lithium-ion/LiPo battery • Operates from 5-25V (minimum LED operating voltage + 2V) • Delivers 1A (12W for 12V LED) or 2.2A (26W for 12V LED) • Can be used with a wide variety of highbrightness LEDs including 6V and 12V (nominal) types • Three brightness settings plus flashing mode with pushbutton on/off and mode control • Low quiescent current when off (around 1mA) • Under-voltage lockout • Overheating protection • High efficiency; typically more than 90% due to the current sense resistor). IC1 is powered from pin 10 (VIN ) and it has an internal regulator (VCCREG.) producing a voltage at pin 9, labelled VCC. This is a ‘negative’ regulator which produces a voltage rail that is relative to VIN, but about 6V lower. The external 1µF capacitor filters this rail. Internally, VCC is fed to the Mosfet gate driver, and this provides the voltage that the Mosfet gate is pulled down to (via pin 6) to switch it on. This gives the Mosfet a gatesource voltage of -6V, more than enough for Q1 to be fully in conduction. To switch it off, pin 6 is pulled up to VIN, so the gate-source voltage is reduced to 0V. The benefit of this scheme is that it allows VIN to be higher than it otherwise could. A typical Mosfet has a maximum gate-source voltage rating of ±20V. If the Mosfet gate were This photo of a “naked” bike light really doesn’t do the LED justice! It is so bright that you risk temporary vision impairment from looking into it – trust us, that is from experience! You can also see just how small the controller board is from this pic. The LM3904 on this board may get quite warm at higher currents, especially if in close proximity to the LED and/ or if in a small housing. In this case, a small heatsink is suggested. The battery, by the way, is a 5-cell, 18.5V, 5000mAh high discharge Li-Po by Turnigy, siliconchip.com.au Australia’s electronics magazine September 2019  101 REG1 LM3480IM3-5.0 IC1 OUT IN GND 100nF 15.8k 4 COFF GND GND 1 2 4 1 GP2 GP0 IC2 PIC PIC10 1 0 F202 -E/OT VSS CON3 1 2 2 OFF TIMER GP1 GP3 LM3409MY 3 + VCC UVLO Finish 3 R CSP 8 R CSN 7 PGATE 6G 35V TANT. 0.22 S CONTROL LOGIC EN 6 Q1 Si4447DY IADJ + 2 PAD 5 TANTALUM CAPACITORS 1 3 0 5 6 V GND WHITE LED + ARRAY – THERMAL PAD UNDERNEATH CONNECTS TO GND LM3840IM3 15MQ040 SC 20 1 9 10W+ LED DRIVER & FLASHER 3 K A 1 Si4447DY LM3409MY 10 2 1 DD 6 S 5 35V TANT. + – 2 A 5R GND 10 F D1 15MQ040 1.24V 1.24V 1 L1 33 H DR74-330-R K 5 A 49.9k 1 UVLO CON2 D 22 A S1 On/Off/Flash/ 16.5k Brightness 10 F 1 F Start 560pF 5 VDD VCC TS1 5 TC6502 TOVER P095VCT VCC VCC REG. 5V 4 9 VIN 100nF – 3 HYST 10 + 12-30V DC IN CON1 + S S G          PIC10F202/OT 65 DD 1 2 3 TC6502VCT 5 4 4 1 2 3 Fig.2: this circuit diagram also shows the internals of the LM3409 IC. It’s a constant off-time switchmode current regulator driving a P-channel Mosfet. The internal negative regulator (Vcc REG.) takes the supply between pins 10 (VIN) and 5 (GND) and produces a third rail at pin 9 (Vcc) which is around 6V below VIN. This determines the low (on) voltage for the Mosfet gate, allowing a supply voltage higher than its gate-source rating. Note the 1µF filter capacitor between VIN and Vcc. The LM3409 IC does get quite warm during operation – heatsinking may be required especially in a small housing. pulled to 0V to switch it on, that would mean that VIN could not exceed 20V. Our recommended 5-cell Lithium-ion battery has a fully charged voltage of 21V, and the circuit can operate to at least 30V thanks to this internal regulator. When S1 is on, the current flowing through it and inductor L1 is sensed via the voltage developed across the 0.22Ω resistor. Both ends of this resistor are connected to a differential amplifier within IC1. The regulated current is determined by the value of the current sense resistor, and the value connected from the IADJ pin (pin 2) to ground, if any. In this application, no such resistor is fitted. If a resistor is fitted there, it changes the 1.24V reference voltage which controls the voltage divider formed by the internal resistors labelled “R” (at pin 8) and “5R”. With no external resistor, 1.24V appears across the “5R” resistor, meaning that 0.248V (1.24V ÷ 5) appears across the upper “R” resistor. Therefore, a similar voltage must be Scope1: the yellow trace (bottom) is the PWM control signal from pin 3 of IC2 to pin 3 (EN) of IC1, while the green trace above is Q1’s gate. The blue trace above that is at Q1’s drain while the mauve trace at top is the voltage across the LED array. The time-base for this grab is fast, at 2µs/div, so you can see the switch-mode operation at 568kHz, with around 100mV of ripple appearing across the LED. Scope2: now we’ve switched the LED to medium brightness and slowed the time-base to 1ms/div, while keeping the same traces and voltage scaling as in Scope1. You can see that the duty cycle is around 80% and the frequency is 200Hz. When the PWM control signal goes low, the LED drive is cut and the LED filter capacitor discharges until the switchmode driver is re-enabled. 102 Silicon Chip Australia’s electronics magazine siliconchip.com.au developed across the external sense resistor for the current amplifier’s output to change polarity. This sets the peak current to 1.13A (0.248V ÷ 0.22Ω), resulting in an average LED current close to 1A. IC1 uses a ‘controlled off-time’ scheme for regulation. With standard PWM, the pulses applied to the gate of Q1 would be at a fixed frequency but with a varying duty cycle. With the controlled off-time scheme, Q1 is switched off for the same time after each pulse; the on-time varies to control the duty cycle. This results in a variable switching frequency. The advantage of this scheme is that it’s easier to stabilise the feedback loop to prevent sub-harmonic oscillation. This avoids the need for external loop compensation components. The combination of the 15.8kΩ resistor from the output to pin 4, and the 560pF capacitor from pin 4 to ground, sets the fixed off-time to be very close to 1µs. So with a 50% duty cycle, the switching frequency will be around 500kHz. Diode D1 is a 1.5A schottky diode with an especially low forward voltage of 0.43V at 1.5A, for maximal efficiency. The resistive divider at pin 1 (UVLO) sets the input supply under-voltage lockout threshold to 5V (1.24V x [1 + 49.9kΩ ÷ 16.5kΩ]). The internal switched 22µA current source adds 363mV (16.5kΩ x 22µA) of hysteresis, so that the switch-off threshold is 5.363V. This was chosen to shut down the circuit before the external control circuitry no longer has enough voltage to run, and to allow lower-voltage batteries and LEDs to be used. It is expected that your battery will have built-in over-discharge protection and so will cease supplying current before it is damaged. If not, you would have to change these divider values to protect your battery. For example, a 5S Li-ion or LiPo battery should not normally be discharged below 3V per cell or 15V total. So you could change the 49.9kΩ resistor to 183kΩ (16.5kΩ x [15V ÷ 1.24V - 1]) (180kΩ would do) and the LED drive will automatically shut off when your battery drops below 15V. Control circuitry Pin 3 (EN, enable) of IC1 is driven from the GP1 digital output (pin 3) of 6-pin microcontroller IC2. This pin is Scope3: this scope grab was taken under the same conditions as Scope2, but now the driver is in low brightness mode, with the PWM duty cycle reduced to around 40%. siliconchip.com.au driven high to light the LED or low to shut it off. It can be modulated (eg, using PWM) to provide dimming. Microcontroller IC2 provides seven different modes: light off, low, medium or high brightness (continuous) or low, medium or high brightness (flashing). These are all achieved by pulse-width modulating or switching the GP1 output state. Onboard temperature sensor TS1 has a digital output at pin 5 (TOVER) which feeds digital input GP2 (pin 4) on IC2. This pin is driven high if the board gets too hot (over 95°C) and IC2 responds by slowly reducing the LED brightness. Its pin 3 hysteresis (HYST) input is connected to Vcc to provide 10°C of hysteresis, so when the sensor temperature drops below 85°, pin 5 goes low again, and the LED brightness slowly ramps back up. This prevents damage to the whole unit if operated for long periods at high brightness in hot weather. If the sensor is at 95°C, the LED array is likely to be well above 100°C, as there will be some distance between them, and no direct path for heat conduction. The various modes are selected using external momentary pushbutton S1, which connects between GND and the GP0 digital input (pin 1) of IC2. IC2 has an internal pullup current to keep this pin high when the button is not pressed. It detects when the button is pressed as that pin is then pulled low. IC2 and TS1 are powered from a 5V rail developed by low power regulator REG1. This regulator can withstand input voltages up to 30V (it is the limiting factor in this design), can deliver up to 100mA and has a quiescent current of around 1.9mA. As it is not a micropower regulator, an external power switch is recommended to avoid discharging the battery when the light is not in use. Scope grabs Scope1-Scope4 below show the voltages at four points in the circuit during different phases of operation. See the captions for an explanation of which each trace represents. Scope1 is a close-up of the switching waveforms, demonstrating how the LED current is regulated. Note how the Scope4: we’ve now switched the driver into flashing mode and slowed the time-base down again, to 100ms/div, so that you can see the full effect. The flashing frequency is around 4Hz, and the duty cycle is 50%. Other flashing modes involve switching between lower LED brightness (PWMcontrolled) and full brightness. Australia’s electronics magazine September 2019  103 Increasing its current delivery Fig.3: because the PCB is so tiny (same-size diagrams at left!) we have also shown the top and bottom at three times the actual size for clarity. Actual size 1 6 . 5 k TS1 D1 IC1 100nF CON1 To battery 3x actual size L1 33 H DR74-330-R While the ~1A current delivery of this design can give you a really bright light (around 2100 lumens), it is capable of delivering more than twice that with a few minor changes, for a CON2 To LED(s) theoretical output of around 5000 lumens, with the right LED(s)! Replacing the 0.22Ω 2/3W resistor with a same-size 0.1Ω 2/3W resistor will set the average current to around 2.2A. You also need to make the following two substitutions. Replace D1 with a 3A schottky diode in the same size package, eg, Comchip CDBA340L-G, Diodes Inc B340LA13-F, On Semi NRVBA340T3G or Micro Commercial SL34A. Replace inductor L1 with Panasonic ETQ-P5M470YFM, with a current rating 2.9A and a saturation current of 4.1A, in a package about the same size as the specified DR74330-R inductor. Two other possible inductor options which are slightly larger are the Murata DD1217AS-H-330M=P3 and Bourns SRN8040TA-330M, both 8x8mm. They will be a tight fit on the existing footprint, but it should be possible to solder them to the board without modifications. Both have slightly lower current ratings than the Panasonic part though; adequate, but barely so. Construction Fig.3 shows both sides of the assembled board at actual size; it’s tiny! The double-sided board is coded 16109191 and measures just 22 x 12mm. We built our prototype by hand with a regular soldering iron (using a standard chisel tip), so it isn’t that difficult, IC2 REG1 Q1 Si4447DY 0.22 49.9k CON3 15.8k gate pulses in green all have the same positive width (off-time) while the ontime varies. This is due to switchmode controller IC1 varying the on-time in an attempt to keep the current through the LED at the target level. Scope2 shows how the 200Hz PWM brightness control from IC2 causes the LED driver output to switch on and off rapidly, reducing both the light output and power consumption. Scope3 shows the same effect but on a lower brightness setting, with a duty cycle of around 40%. Scope4 shows the operation of the unit in flashing mode (4Hz), at a much longer time scale, corresponding to a whole second of operation. 1 F Fig.4: 3x diagrams of the top and bottom of CON2 To LED(s) the PCB. 560pF Besides making sure all the CON3 solder joints are good, the 10 F 10 F main thing to 35V 35V TANT. check is that the pin 1 TANT. dots of IC1, IC2 and Q1 CON1 are in the right To battery orientations, along with the positive stripes on the two 10µF tantalum capacitors. The wiring is shown on both sides as you can solder in the wires from either side. 100nF but it definitely requires some skill and patience. IC1 has closely spaced leads (0.5mm apart) while the other parts are not quite so tricky, but are still quite small so you may need to work under magnification. The board was designed to be so small to leave as much room as possible to fit the battery in your light housing. Fig.4(a) shows where the parts go on the top of the board, and it’s best to start assembly with this side, specifically, by soldering IC1 in place. As well as having closely spaced leads, this part has a thermal pad on the underside. Ideally, it should be reflow soldered, eg, using a hot air rework station. If you have such a station, spread a thin smear of solder paste on all the pads, place the IC in the correct position (ensuring its pin 1 goes towards the nearest corner of the board), then gently heat it with hot air until all the solder reflows. Don’t let the hot air dwell too long on one area or you risk burning the PCB or damaging the chip. The solder under the IC, on the large central pad, is likely to be the last to reflow. But you need to make sure it does, or else you could have hidden short circuits under the chip. If you don’t have a reflow oven or hot air rework station, the PCB pad has been extended slightly past the body of IC1, so that you can still heat the pad directly to solder that thermal pad. The two sides of the completed PCB are shown here rather significantly oversize, (about twice life size) just so you can see what goes where! The 560pF capacitor, 15.9kΩ Ω resistor, 33µH inductor and the two tantalum capacitors mount on the underside (right) – note the stripes denoting the positive end of the capacitors. 104 Silicon Chip Australia’s electronics magazine siliconchip.com.au You will need a fine-tipped soldering iron to do it this way, though To hand-solder this chip, add a small amount of solder paste to the middle of the big pad in the middle of its footprint. If you don’t have solder paste, spread a thin smear of flux paste over the whole central pad instead. Then locate the pin 1 dot or divot on the IC (using a magnifier) and then rotate it so that it’s near the closest corner of the board. Rotate the whole lot so the that the chip leads are on the left and right sides, then add a tiny bit of solder onto one of the chip’s pads (eg, at the upper-right corner if you’re righthanded). Heat this solder and gently slide the chip into place. Having removed the heat, check to see whether its pins are properly aligned with the pads on both sides. If not, heat that solder joint and very carefully nudge the IC slightly in the right direction. We got ours very close on our first attempt (probably close enough) but decided to nudge it a few more times to get the alignment perfect. When you’re happy, add flux paste to both sides, then add solder to the diagonally opposite pin before drag-soldering the rest of the pins on that side of the chip. Return to the other side and solder all the remaining pins, including the one you started with. Bridges are hard to avoid; if you get some, add more flux paste, then use solder wick to suck the excess solder off the pins. When you’re finished, check them carefully under magnification. You should have nice looking fillets on all pins, down to the pads on the PCB. Now add a little extra flux paste to the exposed part of the central pad and feed some solder onto it. Hold the heat on there for a few seconds. If you have solder paste under the chip, it should reflow now. Otherwise, the flux paste under the chip should help suck some solder underneath it (fingers crossed). If you have a hot air rework station, you can still solder the chip by hand, then re-heat it to reflow solder paste underneath the IC. That’s what we did, but again, be very careful to ensure that all the solder paste does melt or you will have trouble later. Also, try not to let the airstream blow the chip off its pads! It helps to keep the airflow rate low. Remaining SMDs With the tricky part out of the way, solder IC2 next. Ideally, it should be pre-programmed (eg, purchased from our online shop), although it is possible to program it later. Find its small pin 1 dot and rotate it so that it is facing towards Q1’s mounting position. Then use a similar technique as for IC1 to solder it in place. It should be somewhat easier due to having fewer, larger, more widely spaced pins. Next, fit TS1 and REG1, both of which can only go in one orientation due to the differing number of pins on each side. Follow with Q1, which has even more widely spaced pins which can possibly be soldered individually. Ensure its pin 1 dot/divot and chamfered edge go towards the bottom of the board as shown in Fig.3(a). The PCB is designed to accept a Mosfet in the SOT-669 package, which has a single large tab in place of pins 5-8, so there is one large pad for these pins. There is no need to worry therefore if you bridge them; in fact, we suggest you add enough solder on that side of the device to form one, large solder joint, as we did on our prototype. There’s also no need to worry about bridges between pins siliconchip.com.au Parts list – Ultrabrite LED Driver 1 double-sided PCB, code 16109191, 22 x 12mm 1 5S Li-ion/LiPo battery or similar, 1Ah+ 1 5S-capable Li-ion/LiPo battery charger 1 2-pin connector to suit battery 1 chassis-mount waterproof momentary pushbutton switch (S1) [eg, Altronics S0960/S0961 or Jaycar SP0756] 1 12V LED array, eg, Cree XHP70.2 P4 bin (2100 lumens at 1A, 4760 lumens at 2.2A) 1 heatsink to suit LED 1 lens to suit LED (optional) 1 DR74-330-R 33µH 1.4A SMD inductor, 7.2 x 7.2mm (L1) 1 waterproof enclosure, large enough for battery and LED(s) short lengths of medium-duty hookup wire or figure-8 Connector options for battery charging 1 waterproof 4-pin chassis-mount socket [Jaycar PS1009+ PS1005 (10A) or Altronics P9444+P9420 (5A)] or 1 waterproof 6-pin chassis-mount socket [Jaycar PS1003+PS1005 (10A) or Altronics P9446+P9420 (5A)] 1 4-pin line plug [Jaycar PP1006 (10A), Altronics P9474 (5A)] or 1 6-pin line plug [Jaycar PP1000 (10A), Altronics P9476 (5A)] Semiconductors 1 LM3409MY switchmode LED controller, MSOP-10 (IC1) 1 PIC10F202-E/OT 8-bit microcontroller programmed with 1610919A.HEX, SOT-23-6 (IC2) 1 TC6502P095VCT temperature switch, SOT-23-5 (TS1) 1 LM3480IM3-5.0 high-voltage 5V linear regulator, SOT-23 (REG1) 1 Si4447DY 40V 4.5A P-channel Mosfet, SOIC-8 (Q1) 1 15MQ040 40V 1.5A schottky diode, DO-214AC (D1) Capacitors 2 10µF 35V SMD tantalum capacitors, low-ESR, D case [eg, Kemet T495D106K035ATE120] 1 1µF 50V X7R SMD ceramic, size 3216/1206 2 100nF 50V X7R SMD ceramics, size 1608/0603 1 560pF 50V X7R SMD ceramic, size 1608/0603 Resistors (all 1% SMD 1/10W, size 1608/0603 unless otherwise stated) 1 49.9k 1 16.5k 1 15.8k 1 0.22 1% 2/3W, size 3216/1206 [eg, Susumu KRL1632EC-R220-F-T1] 1-3 as these all connect to the same point, but you don’t want to bridge pins 3 & 4 as pin 4 is the gate. You can still use flux paste and solder wick to clean up a bridge between these pins, should it occur. You can now fit diode D1, with its cathode stripe orientated as shown, followed by the three resistors and three capacitors. Make sure you use the correct values for the two smaller resistors. Components on the other side Now flip the board over. There are just five components to mount on this side of the board, as shown in Fig.3(b). Unfortunately, the board will not sit flat at this stage, so you should find some small plastic shims to place strategically under it so that it won’t wobble around as you are soldering these final components. Start with the two smaller components, making sure that Australia’s electronics magazine September 2019  105 The Cree XHP70 is shown at left close to life size, with a larger scale front and back image at right. It must be used with a heatsink; otherwise it would destroy itself. The star-shaped Meodex at bottom right not only provides some heatsinking but is also a convenient means of connection. you fit the capacitor in the position closer to the board edge. You can then solder the two larger capacitors in place. It helps to have fine tweezers when doing this, as they are quite close together. As usual, make sure the striped ends are orientated correctly. That just leaves the inductor. Spread some flux paste on its pads, then use the usual technique to tack it into place before soldering the opposite lead. Put some heat and solder into the joints to make sure the fillets look good on both sides. Preparing the LED You may be able to buy a suitable LED pre-assembled and ready to wire up, but the recommended Cree XHP70 LED generally comes as a bare ‘chip on board’ type LED, which needs to be soldered to a suitable PCB both for electrical connections and to get heat out of it. This is then generally attached to a piece of metal which acts as a heatsink to keep the LED temperature under control. It’s a good idea to then mount the PCB on the back of this heatsink (with a suitable layer of electrical insulation in between!) so that the PCB can sense the heatsink temperature and reduce the LED brightness if it’s getting too hot. But we’re getting ahead of ourselves. First, you need to solder the LED to this PCB, which is often in a ‘star’ shape. Note that the XHP70 can be run at 6V or 12V, depending on the configuration of the PCB, so make sure you get a suitable PCB that’s designed to run it at 12V. Otherwise, the LED will require twice as much current for the same brightness. You can sometimes get the LEDs pre-soldered to the star boards, but we couldn’t find one locally, so we ordered the LED and board separately from Cutter Electronics in Victoria (www.cutter.com.au). We then attached the LED to the board. First, we checked the T-shaped marking on the underneath to identify the anodes and cathodes; the bar across the ‘top’ of the T indicates the cathode. This goes towards the side of the star PCB with the negative (-) pads on it. We then covered all the LED pads (two small rectangles plug a larger Z-shaped pad) with a thin smear of solder paste mixed with some flux paste, placed the LED on top and gently applied heat from a hot air rework station from underneath the board. We did it this way to avoid overheating and damaging the LED lens. Make sure the small pads on the underside of the LED line up with the two small rectangles on the star board. We managed to heat the star PCB from underneath by clamping it with a hemostat (self-closing tweezers) and then clamping that in a vice, giving us access to the underside of the board without having to hold it. You definitely don’t want to hold an aluminium PCB while heating it to over 200°C! We had to gently nudge the LED using a metal object when the solder reflowed to get it properly centred on its pads. In theory, it should pull itself in due to solder surface tension, but ours got ‘hung up’ on something and needed some help. Wiring & testing The next step is to solder wires to the board for the control pushbutton (S1), battery power and the LED(s). As the board is so small, the wire holes are too, so you aren’t going to be able to solder heavy leads to it. You’ll be keeping the wires fairly short anyway, so medium-duty hookup wire is adequate. You will probably need to cut away some of the wire strands at the exposed end, so that you can twist the remaining strands together to fit through the holes in the PCB before soldering them. The current will quickly spread out through the other strands in the wire, so this should not cause any problems. But make sure you don’t leave any loose strands that can short to anything else! Now solder the two LED wires from the board to the + and – terminals on the LED star, then use screws and thermal paste to attach it to a heatsink. Solder the momentary pushbutton to the end of its wires; its polarity doesn’t matter. Before powering it up, carefully inspect both sides of the board, looking for short circuits between any of the wire solder joints and nearby components, between components or component pins and also to ensure that all pins have good fillets, touching both the pin and the pad. Magnification and good lighting are critical to successfully inspecting a board populated with tiny SMD components. It’s also a good idea to clean it thoroughly beforehand, using a specialised flux solvent or alcohol (isopropyl, pure ethanol or methylated spirits). Otherwise, flux residue can get in the way of a proper inspection. Once you’re satisfied that it has been assembled correctly, its time to power it up. Having trouble holding the LED in place while you solder it? Here’s how we did it: a pair of tweezers held tight in a bench vice, with the LED held firmly at the opposite end! A wooden clothes peg (NOT plastic!) also works well! 106 Silicon Chip Australia’s electronics magazine siliconchip.com.au If you have a suitable DC voltage source such as a 1524V 1A DC plugpack or bench supply, you can now test the unit. Wire up the supply leads and use some electrical tape to make sure they can’t short together, then switch on power. At first, nothing should happen. If your supply has a current meter, you should get a reading of no more than a few milliamps. If the current reading is significantly more than that, switch off and carefully examine your board and wiring for faults. Now press the pushbutton, and the LED should come on. Depending on the supply voltage, you should see around 500mA being drawn from the supply; slightly less if its output voltage is significantly above 15V. Brief presses of the button again should change the brightness — cycling between medium, low and off. Holding it down for a few seconds should switch the LED on at full brightness. If you continue to hold it, the LED should start it flashing. Once it’s flashing, brief presses of the button will change the flashing mode; hold it down for several more seconds to switch the LED off. If it doesn’t work, most likely you have a soldering problem, or one of the components is in the wrong location or was fitted with the wrong orientation. Carefully inspect the board for problems. If you don’t find any, try adding flux paste to all the small IC leads and re-flow them all, either with a soldering iron that has a clean tip or (even better) a gentle application of hot air. Re-test to see if that fixed it. Once you’re sure it’s working, switch off the power, disconnect the test supply and solder the battery connector onto the end of the supply wires. Make sure you get the polarity right (very important!) and use heatshrink tubing to insulate the solder joints. There are several common types of lithium-ion battery connector so you will need to obtain one that matches your battery (usually from the same source). We’ve seen connectors with red/black wire colour coding that’s actually the opposite of the supply polarity once it’s plugged into the battery. So check yours, and if this is the case, use red and black heatshrink tubing to change the wire colours to avoid mistakes. Placing inside your bike light At the outset, we designed this project “tiny”, so it could fit inside a bike light. However, because every bike light is different, we can’t offer much guidance here. It may be that you have an old dynamo-type bike light set gathering dust in a cupboard; these have been largely superseded by modern lamps which also save your legs somewhat when pedalling up a hill! But most of these older-style lights had a fair bit of room inside the light itself (because there was no battery). One of these could be worth experimenting with. The battery will need to be mounted in its own case external to the light – though this could be beneficial when it comes to charging. We should warn you though that many bike lights (especially plastic ones!) may not like the heat of the ultrabright LED, so you may need to come up with some arrangement which ensures your bike light doesn’t melt. Putting it in a case However, if you need to mount the project in a new case, siliconchip.com.au Old-style tyre-driven dynamo bike lights (remember them ... puff, puff!) have been largely superseded but if you can find one, it should be possible to mount the LED and control board inside the headlight. Just beware of the heat generated by the LED, although it may not be much different to the heat of a recent “halogen” incandescent bulb which ran very hot. the following points might help you. The case should ideally be a waterproof one if you’re going to be using it on a bicycle, or anywhere external where it could be in the weather. You will probably have to install a waterproof transparent window so that the LED itself can be mounted inside the box. It can be made from clear plastic and sealed with silicone sealant. You should also seal around the pushbutton switch to ensure water cannot enter that way. The battery and board should be securely anchored inside the box so that they can’t put any strain on the wires. That just leaves the question of how you charge the battery. You could open the box up and remove the battery to charge it each time it runs low (or just swap it for a fresh one), but that’s hardly convenient. To charge the battery without removing it, you will need to fit a waterproof socket to the case and make up a cable with a matching plug to connect to a suitable lithium-ion battery charger. If you do this, it’s vital to choose a connector where you can’t accidentally short the pins. That could melt the connector or even damage the battery. Ideally, multi-cell (series) lithium-ion/LiPo battery packs should be balance charged. In the case of a 5S battery, that requires at least six contacts, two of which will carry the full charging current. But you can get away with the occasional balance charge, so you could compromise by taking the battery out from time to time, and simply fitting a two-pin connector for day-to-day recharges (although some connectors are not available with fewer than four pins). Another option is to build our March 2016 Battery Balancer (www.siliconchip.com.au/Article/9852) and mount it inside the case, permanently attached to the battery’s balance connector. That way, it will automatically be balanced each time you charge it. It is a relatively small board, so you should not have trouble fitting it, and it draws little current when not active (around 25µA). We suggest that you use a four-pin chassis-mount socket for regular charging, with the pins wired in pairs for extra current handling, or a six-pin socket for balance charging. Suitable connectors are available from both Jaycar and Altronics; see the parts list for details. Don’t forget to insert the waterproof gasket (if supplied) SC when putting the lid on your box. Australia’s electronics magazine September 2019  107 CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions will be paid for at standard rates. All submissions should include full name, address & phone number. High-frequency adjustable LED strobe I have a friend working in the nanotechnology field and he wanted to be able to see the movement of microscopic particles, which requires pulses of light in the microsecond range. This is much shorter than conventional strobes but I thought it would be achievable with LEDs. I designed this circuit to drive those LEDs. The circuit includes both a freerunning oscillator with adjustable frequency, which pulses the LED(s) like a conventional strobe, and also a section which produces pulses of light in response to a triggering voltage, with an adjustable delay and also an adjustable pulse width. All seven internal stages of a ULN2003A Darlington IC are used to drive the white LED(s). This is capable of sinking up to 2.5A in total, which with a 12V supply, equates to a total LED power of around 25W. This could be even higher if a higher LED supply 108 Silicon Chip voltage is used with an appropriate array (up to a maximum of 50V). You need to select a suitable resistor value (R1), taking into account the power rating of your LED and the ~10.5V across the LED and resistor when the Darlington array is switched on. That figure is assuming a well-regulated 12V supply is used. The free running trigger signal is generated by NAND gate IC1a. One input is grounded by a 10kW resistor but it can be connected to 12V by switch S3 to enable the oscillator. The charge and discharge paths are isolated by small signal diodes so that the timing of the negative output pulse is controlled by a 4.7kW fixed resistor, while the duty cycle is controlled by the second 4.7kW resistor and series 100kW potentiometer VR1. This allows you to adjust the duty cycle. The repetition rate is determined by the setting of VR1 and the position Australia’s electronics magazine of switch S1, which selects between five different timing capacitor values. These give pulse adjustment ranges of 1-20µs (330pF), 10-200µs (3.3nF), 100µs-2ms (33nF), 1-20ms (330nF) and 10-200ms (3.3µF). The output signal from IC1a is buffered and inverted by IC1b, to provide pulses with a positive-going leading edge. With switch S4 in the correct position, these pulses are fed to the inputs of the Darlington output stage via a 1kW current-limiting resistor, so the pulses from IC1b switch on the LEDs. With S4 in the alternative position, trigger pulses for the Darlington array come instead from pin 10 of IC2b, half of a 4098B dual monostable multivibrator. This is configured to deliver a variable width pulse, adjusted using trimpot VR3 and switch S2b, which selects one of four different timing capacitors: 100pF (1-10µs), 2nF (10-100µs), 47nF (100µs-1ms) and 470nF (1-10ms). IC2b is triggered by IC2a, configured siliconchip.com.au identically, which provides an adjustable trigger delay via trimpot VR2 and switch S2a. IC2b is triggered using its negative trigger input (pin 11) so that its output pulse starts as soon as the pulse from IC2a finishes. IC2a is triggered by an external signal via a 4.7kW current-limiting resistor, with a 100kW pull-down to prevent triggering in the absence of a signal. IC2 can therefore be used to synchronise the flashes to a camera or another piece of external equipment, as long as it can provide a trigger pulse, with a delay and flash time chosen to suit the particular circumstance. Alternatively, you can use switch S5 to route the continuous pulses from IC1 through to IC2a as well as the trigger input, which becomes an output. These pulses can then be used to trigger the camera (or another external device) and they are also fed to IC2a so that after the chosen delay, the LEDs switch on for the period determined by IC2b. Note that the trigger input/output voltage swing is 12V, as this circuit runs from a 12V supply. If your external equipment needs or has a different voltage swing, you may need to add level translation (eg, a simple transistor) to the trigger input. The 4.7kW resistor should prevent damage to external equipment as long as it has an input clamping diode to its own positive supply. White LEDs work very well with this circuit, even with pulses down to around 1µs, it is also possible to drive a laser diode. I suggest that a 470W current-limiting resistor would be suitable for driving a laser. But note that you can’t use a green laser as these are actually an infrared laser pumping a small crystal to double the frequency. These work well at very low frequencies but visibly dim as the frequency increases because the crystal takes time to produce an output. As a result, when the drive frequency increases, the output consists more and more of infrared light. Apart from amusement, this circuit could be used as a replacement for the old Xenon timing lights for servicing cars. Note that in one microsecond, a rifle bullet only moves about one millimetre. That would make for some interesting strobe photography! Graham Jackman, Melbourne, Vic ($80). siliconchip.com.au Top octave generator using AVR micro In the 1970s, numerous electronic musical instruments were designed using a chip known as a Top Octave Generator (TOG). Almost all of the TOGs used an input frequency derived from a 2MHz crystal oscillator circuit to provide 12 or 13 square waves for each musical note in an octave, by dividing this input frequency by factors from 239 to 478. This provided square waves with frequencies between 4434 and 8368Hz. Lower frequencies were generated, for additional octaves, by dividing each output by powers of two using counter ICs. People repairing these instruments can source suitable divider ICs, but the TOGs are no longer made. Custom chips or old stock are available but are expensive. An alternative solution is to create a TOG using software but it's a bit tricky due to the “real-time” requirements. Creating the software TOG was a learning exercise for me. The resulting program is written in assembly to suit a 16MHz ATmega328P AVR processor – ie, the same one used in the Arduino Uno and compatible boards. An Arduino Pro Mini with a 16MHz crystal and ATmega328P processor can be purchased from overseas for less than $3. The firmware .hex file was created using AtmelStudio 7 and I programmed it into the Pro Mini using avrdude driving an Arduino-compatible FT232RL USB/Serial Adaptor (also costing less than $3). The program was written to be a faithful emulation of a TOG IC driven by a 2MHz clock. The ICs attempt to produce an equal tempered scale, where the note pitches are based on the twelfth root of two. This is the scale in common use for instruments with fixed tuning such as pianos. The TOG IC notes are not exact, but close approximations. Because the ATmega328P has a 16MHz clock, the divider values used in the program are eight times the values used in the original TOG. This allows the division Australia’s electronics magazine values for some notes to be closer to the exact equal-tempered scale pitches. The downside of doing this is the outputs have to align with a notional 2MHz clock, so appear to jitter. When the signal is feeding a divider, the jitter disappears after dividing by eight. It is an area for experimentation. Another area for experimentation is using different scales. The period information is held in flash memory and copied into RAM as part of the initialisation process. There is enough spare flash memory to have hundreds of 12-note scales; a selection mechanism would be needed to decide which scale to copy to RAM. The program is written so that in idle time, the flash memory data is repeatedly copied to RAM. This is not required when using a single scale, but opens the opportunity to change scales on the fly. The program is quite convoluted, to minimise the number of instructions needed. There is much duplication of code; program memory is plentiful, so speed takes priority over compactness. The source is heavily documented to help explain how it works. Both the source code (TopOctaveP3.asm) and firmware (TopOctaveP3.hex) are available for download from the Silicon Chip website (siliconchip.com. au/Shop/6). Alan Cashin, Islington, NSW ($80). September 2019  109 Formula 1 starting lights for slot cars This simple circuit uses a humble shift register to implement a set of starting lights that light up one at a time, stay on for an unpredictable period of between one and five seconds, then go out to signal the start of the race. And if a car spins off the track, you can change to light to flash orange for danger! The project uses three simple 74HC series logic chips and a 555 timer to implement the random delay. It is ideal for beginners as it can be built on stripboard. The LEDs are wired together in a box, with red LEDs3-7 arranged horizontally and yellow LEDs1-2 above them, with a larger gap between them. For my prototype, I used some Lego Technic bricks that look like traffic lights, attached to a Lego Gantry. The lens of a 5mm LED is slightly bigger than the hole in a Lego block, but the block can be reamed out slightly to accept it. 110 Silicon Chip I used Adafruit RJ45 breakout boards to connect the LEDs. You could use an RJ45 punch down socket or similar. IC4 is a serial-in, parallel-out shift register which is used to drive LEDs3-7. Its pin 8 clock input is connected to the output of an astable timer based on 7555 timer IC2 via switch S2b. When pushbutton S1 is pressed, IC4's reset pin is released and with S2b in the upper position, this causes LED3 to light first, then LED4 and LED5 and so on until they are all lit. This is because the SDa and SDb inputs of IC4 are tied high, so after it comes out of reset (and its output states are all low), 'ones' are shifted in on each clock pulse, causing the outputs to go high in sequence. There is then a one-second delay, after which output pin O6 goes high. This is fed to a set/reset flip flop formed from the four gates in IC1, a 74HC00 quad NAND logic gate chip. This signal goes to pin 5 of IC1b, but Australia’s electronics magazine when this pin goes high, nothing happens until the other input pin (pin 4) also goes high. This is driven from the Q2 output of IC3, a 74HC193 synchronous 4-bit binary up/down counter. IC3 is also clocked from 7555 timer IC2, and it runs freely and asynchronously with the shift register. So the Q2 output of IC3 could already be high when the O6 output of IC4 goes high, or there may be a delay of up to four seconds before both go high, setting the flip flop and thus resetting IC4 (via its pin 9 master reset input), switching off LEDs3-7 and starting the race. You can extend the maximum possible delay to nine seconds by using the Q3 output of IC3, rather than Q2. While delays that long are used in Formula 1 races, it proved a little too dull for my little ones, so I switched to using Q2 instead, for a total delay of between 1 and 5 seconds. In most cases (50% of the time), there is only a 1-second delay. Otherwise there is an equal (12.5%) chance of a two-second, three-second, four- siliconchip.com.au second or five-second delay. This makes for an exciting start to any race. When there is a crash or a car flies off the track, a flick of a switch S2 sets the lights to flashing yellow, to show there is a track incident and to give you time to retrieve your car before setting the lights up to start again. With S2 in the alternative position, the flip-flop is automatically reset to switch off the red LEDs, and the yellow LEDs are driven from the timer circuit via NPN buffer transistor Q1. IC2, the 7555 timer, is configured to produce a square wave of about 1Hz due to the combination of the 10µF Six-decade resistor sorter Testing resistors using a multimeter can take a long time if you have a large number of resistors. For each resistor, you need to wait for the meter to auto-range and then for its reading to stabilise. This resistor sorter simplifies the process by enabling you to pre-sort the resistors into six groups. The reduced range of resistor values within these groups makes it easier to read the colour codes. Alternatively, having sorted the resistors, you can set your multimeter to the correct range for each group and then measure their values much more rapidly. This sorter's indication is instant. As soon as you connect a resistor, the appropriate LED lights up to show you which resistance range it falls within. I developed this unit after accumulating a large number of mixed resistors, left over from many electronic projects. Several wattage ranges were included, with both 4 and 5 colour bands and a range of body colours, making it very difficult to read the resistance values quickly. The resistor to be tested is connected to the test clips X1 and X2, then power button S1 is pressed, causing one or more of the LEDs to be illuminated. The lowest range LED that lights up siliconchip.com.au indicates the group the test resistor is from. If you press S1 without a test resistor fitted, all the LEDs remain off. Resistors near the edges of the ranges could go either way due to component tolerances. This tester uses three LM358 dual op-amps as six comparators to detect the resistance ranges shown at the bottom of the circuit diagram. The comparators have individual resistive dividers which provide a reference voltage to the inverting inputs. The non-inverting inputs are all connected together and go back to the junction of the resistor being tested and two fixed resistors, with a total resistance of 1082W. So depending on the value of the resistor connected between X1 and X2, a particular voltage is fed to the non-inverting inputs of each stage. If this is higher than the reference voltage fed to that comparator's inverting input, its output pin goes high, lighting up the connected LED. Depending on your requirements, you could fine-tune the voltage level for one or more stages by altering the ratio of the two resistors at the inverting input of each comparator. You do this by changing the value of either resistor. You could even connect a trim- Australia’s electronics magazine timing capacitor and 8.2kW/68kW timing resistors. The circuit is powered from the slot car power supply, 16V AC, via a bridge rectifier formed by diodes D1-D4, a 100µF filter capacitor and 5V linear regulator REG1. Martin Walker, Burnham, UK. ($80) pot in the middle of each voltage divider, with the wiper going to the op amp input, to make it easier to adjust. Also, if you use high-brightness LEDs, you could increase the values of the 680W LED current-limiting resistors, which would reduce the circuit's power consumption. The sorter runs on a 9V alkaline battery and has a pushbutton power switch to increase battery life considerably. The battery directly supplies power to the three ICs at pins 4 & 8 while the various resistive dividers are fed from a 2V lower rail voltage that is provided by the drop across LED7. The 82W resistor below the resistor under test is optional and was added to my prototype, to fine tune the voltage level on the non-inverting inputs; you can alter this resistor value as required. This project can be built on prototyping board or strip board and then housed in a small Jiffy box. Use 1% tolerance resistors. The LEDs used are not critical; I used 3mm red LEDs mounted on the board and lined up with holes in the case. The power button S1 should have tactile or snap action contacts and be chassis-mounted. Crocodile clips on short leads can be used for test terminals X1 and X2. Ian Robertson, Engadine, NSW. ($70) September 2019  111 Phone call speech time warning (sales booster) There’s a sales joke that goes like this: “You can’t buy yet. I haven’t finished my pitch!”. Many salespeople get so caught up in talking, they forget that it’s only by listening to the customer that they can make a sale. This is a significant problem in any sale that happens over the phone. Sometimes, a salesperson will fail to make a sale because they simply can’t stop talking. I designed and built this device to help one of my staff who had that very problem. Even though he knew he should talk less, once he was in full sales mode, it was hard for him to remember to stop and listen. The device consists of two parts: an Arduino-based box which plugs into a USB socket (but only as a power source) and a cable that leads to a microphone and LED that sticks to the side of a computer monitor. Its operation is very simple. If the salesperson talks for more than a set time (selectable on the box) without a pause, the LED goes on. If they talk for much longer than that, the LED flashes. The negative side of the microphone is connected to GND via the shield of its connecting cable. It is powered Circuit Ideas Wanted 112 Silicon Chip via a 4.7kW resistor which provides around 1mA, sourced from a filtered 5V rail from the Arduino Nano, with a 100W series resistor and 220µF capacitor used to reduce noise in the power supply. Quad LM324 op amp IC1 amplifies the signal from the microphone. The low-level signal is AC-coupled to op amp stage IC1a via a 15nF capacitor, and this first stage has a gain of -10, set by the ratio of the 4.7kW and 47kW feedback resistors. The second stage, based around IC1b, again has a gain of -10, so the overall gain to its output pin 7 is -10 × -10 = 100 times. The third stage, based around IC1d, has an adjustable gain from near-zero to around two times, set using trimpot VR1. The non-inverting inputs of these three op amp stages are connected to a 2.5V virtual ground formed by a 10kW/10kW resistive divider across the filtered 5V rail. This provides the DC bias for each op amp gain stage, keeping the signal between the op amp's 0V and 5V supply rails. The amplified signal is fed into the Arduino's A0 analog input so that it can sense when the salesperson is talk- ing. Op amp stage IC1c is not used, so its inputs are tied to ground. The Arduino's D3 digital output drives LED1 via a 100W series currentlimiting resistor, with a 470nF capacitor to suppress electrical noise when it switches on and off. Trimpot VR2 forms an adjustable divider across the 5V rail, feeding the Arduino's A2 analog input, allowing you to set the ‘talk time’ before the LED comes on. Set-up is simple: reduce VR2 to its minimum setting, making the talk time zero. Then adjust VR1 to a suitable sensitivity by rotating it until the LED lights only when you’re talking. Then set VR2 to a suitable talk time; the maximum setting is one minute. Most of the ‘smarts’ are in the Arduino sketch, which can be downloaded from the Silicon Chip website. It implements a variable sampling frequency (up to 500Hz), a programmable bandpass filter which defaults to 70-250Hz, the typical fundamental frequency range of the human voice, plus an RMS measurement routine. Phil Cohen, Sydney, NSW. ($75) Got an interesting original circuit that you have cleverly devised? We will pay good money to feature it in Circuit Notebook. We can pay you by electronic funds transfer, cheque or direct to your PayPal account. Or you can use the funds to purchase anything from the SILICON CHIP Online Store, including PCBs and components, back issues, subscriptions or whatever. Email your circuit and descriptive text to editor<at>siliconchip.com.au Australia’s electronics magazine siliconchip.com.au Vintage Radio By Associate Professor Graham Parslow Kriesler Farm Radio model 31-2 At first glance, this radio looks like the common Kriesler model 11-7. But it’s actually a 31-2, which (for most of its production run) recycled the same case. This was done to save money and take advantage of its very recognisable shape; thanks to a strong advertising campaign for the 11-7. This radio is powered from a 6V lead-acid battery, and was intended for use on farms. This Kriesler radio was made for use on a farm, operating from a single 6V battery. The first of the model 31-2 line was released in 1946 with a timber case (not Bakelite). Anyone familiar with the popular Kriesler “breadbox” radio manufactured from 1947-1952 might suspect that the radio featured here is a model 11-7. Indeed, the bottom of the case has “model 11-7” moulded into the Bakelite, but appearances are deceiving. The Bakelite breadbox radio was strongly promoted at the time, particularly with the phrase “triple throated”. This is because three grilles act as sound sources: the honeycomb front grille and two vents in the top of the case. Catchy as the promotional line is, this conveys no acoustic advantage to the design. Even so, many collectors regard the sound reproduced by the modestlybaffled 6-inch Rola speaker as better than most contemporaries. This radio is best categorised as a table model. It is 400mm wide and 114 Silicon Chip weighs a hefty 9.7kg. The mains-powered model 11-7 weighs 10.6kg due to the added transformer. This radio comes at the apex of the Bakelite period, before thermomouldable plastics displaced Bakelite through the 1950s. Manufacturing this substantial Bakelite case required expensive high-pressure moulds. The pay-back was a low unit cost when produced in large quantities. Repurposing the model 11-7 case for a farm radio made good sense because of the economies of scale for Bakelite pressing and the bonus of the advertising associated with the case. The model 31-2 has five octal valves and this example is firmly dated to 1950 by the date stamped on the filter choke (L3). Circuit description The circuit of the Kriesler model 31-2 is shown in Fig.1. It is a rather standard five-valve superhet, although it has a few interesting features that I shall now describe. Australia’s electronics magazine Farm radios were designed to run from various DC voltages, with 6V and 32V being the most common. Many cars of the time had 6V batteries, so maintaining and charging a 6V leadacid battery was relatively easy. A vibrator provides the high tension supply. Vibrators use mechanical oscillators, analogous to simple electromagnetic buzzers. Once an interrupted DC supply is created, a transformer can be used to step up the voltage as required. The V5124 six-pin plug-in vibrator in this radio is the synchronous type, with an extra set of points that take the place of a rectifier valve. The internal circuitry of this module, along with a couple of the external components (to aid in understanding its operation) is shown in Fig.2. Both sets of contacts are mounted on the same vibrating reed, as indicated by the dashed line, and this operates at 100Hz. Contacts “A” alternately connect each end of the primary to ground; the centre-tap is permanently connected siliconchip.com.au Fig.1: the Kriesler model 31-2 circuit, showing the socket for the vibrator (V5124; its circuit is in Fig.2) and the supporting components required to step up and filter the 6V battery supply, inside the dashed box titled “Vibrator Unit 19-1”. The vibrator itself is essentially a DPDT relay that self-oscillates at 100Hz. The V5124 pinout starting from the right and going clockwise is: primary, reed & can, primary, secondary, driving coil, secondary. to the +6V battery terminal. Simultaneously, the second set of contacts at “B” alternately connects each end of the secondary to ground, rectifying the 150V which appears at its centre tap, as this keeps the two halves of the transformer in-phase. This is equivalent to a full-wave rectifier. The polarity of the input voltage is important. Reversed polarity will cause the rectified output voltage to be negative. In this radio, the components in the dotted-line box on the circuit diagram are in a canister mounted where a mains transformer would have been in the model 11-7. The canister is designated “Vibrator unit 19-1”. The inductors and capacitors packaged with the vibrator ensure a well-filtered hightension supply of 150V. In 1950, many farm radios were switching to miniature valve types, yet this radio uses octal valves. It may be that Kriesler had a large stock of octal valves, so the model 31-2 circuit of 1946 remained attractive. Another motive for using octal types was that this meant that they could re-use the same punched chassis from the 11-7; by my reckoning, the chassis used in siliconchip.com.au the 31-2 is identical. The physical layout of this chassis would not scale well to a three-gang tuning capacitor. This may explain why an RF amplification stage, which would require a third capacitor gang, is not incorporated. It’s a pity, as this would improve reception in remote areas. However, there are punched holes for three IF transformers, so they were able to add another 455kHz IF amplification stage. The front end has the external aerial switched between two aerial coils via DPDT switch S1; one for MW and the other to cover 6-18 MHz (1650m). Matching local oscillator coils ensure that the mixer/converter valve (type ECH35) operates with a fixed 455kHz IF. The 1K7 has two internal diodes. One acts as a detector for the output of IF transformer three (designated IFT5 on the circuit diagram). After passing through C27A (10nF) to block DC, the audio signal goes to the 1K7 grid from the wiper of the 0.5MW volume control. The second diode feeds a negative AGC voltage back to the ECH35 and first 1M5 via R146A (1MW). Amplified audio from the anode of Fig.2: the internals of the vibrator unit. This diagram also includes the transformer and filter capacitor which are external (and shown in Fig.1), to aid in understanding its operation. Contacts “A” alternately ground one end of the primary, driving the coil with alternating polarities to cause oscillation. Contacts “B” alternately ground one end of the secondary, rectifying the transformer’s output voltage. Australia’s electronics magazine September 2019  115 Shown above are the Kriesler 31-2’s Bakelite, not timber, case as purchased (left) and the rear of its chassis after cleaning (right), with the V5124 vibrator, shown at the upper right corner in the larger canister. You can clearly see the green wires connecting the top control grids of each valve to the IF transformers and tuning gang. the 1K7 valve passes to the three-position tone control switch, S3. The three tone choices are (1) straight through after the primary coupling capacitor, (2) bass cut by switching in an extra capacitor in series and (3) top cut by adding a capacitor to Earth. The circuitry around the 1L5 output valve is minimal. There is no negative feedback from the secondary of output transformer T2. The 1L5 is directly heated with the filament serving as the cathode. The grid bias of the 1L5 is set by the filament chain of connections between the valves. Pin 2 of the filament is at +6V and pin 7 is at +4V, giving an effective grid bias of -5V. Radios with all directly-heated valves usually turn on and function without significant delay, much like a transistor radio. Although four of the valves are 1-series types with direct heating, this radio has a prolonged warmup period due to the ECH35 converter, which is a 6V indirectly heated valve. Radio construction The photo of the chassis shown above is after cleaning, but before full restoration. The vibrator canister can be seen in the upper right corner. The ECH35 (made by Philips) is easy to spot due to the metalised shield coating, painted red, that connects through octal pin 1 to Earth. That photo also shows the first four valves with top-cap control grids con- As is the norm with these types of restorations, all electrolytic and high-voltage paper capacitors were replaced. 116 Silicon Chip Australia’s electronics magazine nected by short lengths of wire to their signal sources. This arrangement avoids the potential injection of noise from longer hook-up wiring that would have been required if the grids were terminated via the octal base pins. The two IF amplifier valves (type 1M5) are well shielded, and for good measure; the detector preamplifier valve (type 1K7) is also shielded. Most comparable radios in 1950 used a miniature 3V4 valve for audio output. By contrast, the 1L5G is enormous and its internals are clearly visible. The G (glass) designation in the 1L5G valve specifies the classic envelope shape that was near-universal in the 1930s. The 1L5G valve in this set is a Philips Miniwatt made in Australia. Few sets made after this date would have an all octal, all type-G valve lineup. The 1L5 presented with two bands of perished rubber as seen in the chassis photo after cleaning. I removed the perished rubber from the 1L5 to improve its appearance. There is a pleasingly simple linearity to the above chassis arrangement of this radio. Unfortunately, this is not reflected under the chassis. The bulky components, notably the electrolytics and paper capacitors, were installed with little concern for easily locating specific components or making repairs (see photo at left). The large pink electrolytics are 500µF 12VW types made by Ducon. The marks on them show that the set got wet at some point in its life. Restoration This radio was previously owned siliconchip.com.au by Rob Coleman, a singular character who enjoyed recounting his times as a technician at Channel Nine in the golden years of the sixties through to the nineties. His best stories were about the behind-the-scenes crises and horse-play in the days of In Melbourne Tonight and Hey Hey, It’s Saturday. Rob was an inveterate acquirer, and this radio was part of a pile in his backyard, largely exposed to the elements. Rob served for many years on the committee of the Historical Radio Society of Australia (HRSA), so it was fitting that the HRSA assisted in the sale of his collected items after his death in 2017. But at the end of the day, no one had taken this orphan home. Bakelite has never looked duller than on this weather-worn radio. The original dial calibration and one knob were missing and the dial string was broken. That’s probably why no one else wanted it. I purchased the radio to clear the table. My tepid enthusiasm to restore it was elevated when I discovered it was not just another model 7-11. Removing the bottom panel revealed exactly what I expected – spider webs, water marks and worm castings. Thankfully, there proved to be no faults in the densely-packed shielded box housing the aerial and oscillator coils. You might notice a yellow stalactitelike intrusion of wax that had melted through from the vibrator canister above. Fascinating! My conclusion was that wax had been used as a noise suppressant to muffle the 100Hz buzz of the vibrator. sirable effect of decluttering the underside of the chassis and making the valve pins more accessible. Some fruitless hours passed, with the radio remaining dead and voltages making little sense, until that ‘Eureka!’ moment when it all made sense. Corrosion internal to the pin 7 socket of the 1L5 was causing erratic contact between the valve filament and the power supply. Inspection of the filament cascade of series and parallel connections in the circuit diagram will show how an imperfect connection of the 1L5 will cause other valves in the chain to lose function. Although the 1-series of valves nominally work with 1V across their filament, they need at least 1.5V for good performance. All of the 1-series valves in this radio operate at 2V (6V ÷ 3). Fixing the pin 7 contact did not completely fix the radio. The RF section remained dead and external audio fed in came out highly distorted. Swapping the 1L5 and replacing the output transformer did not fix this distortion. The first replacement speaker I used The 6in Rola speaker was replaced as the coil was jammed and the cone damaged. However, the output transformer was good enough to reuse. Troubleshooting a dead radio I decided to bypass the vibrator in restoration, and simply use an external 150V DC supply. Sadly, the speaker coil was jammed hard, so I tossed it in the bin. I fitted a replacement speaker but retained the original output transformer. The electrical components looked like they might all be serviceable. Ever the optimist, I connected bench supplies of 6V and 150V (ramped up from zero), but got nothing. There was no output from the RF stages at the volume control and injecting a signal at the 1L5 grid also produced no output. The next step was to replace all electrolytics and high-voltage paper capacitors. Because of the smaller size of the replacements, this has the desiliconchip.com.au The internals of the Kriesler 31-2 were in a mess, with loose parts scattered around along with dirt and insects. Australia’s electronics magazine September 2019  117 An advert for a Kriesler table model radio (likely the 11-7) which shared its case design with the 31-2. Source: Australian Women’s Weekly, May 1951, Page 51 – https://trove.nla.gov.au/newspaper/page/4388702 118 Silicon Chip Australia’s electronics magazine siliconchip.com.au The internals of a non-synchronous V4012 vibrator. Oak vibrators were unique in that they had a secondary winding on the driving coil which is short circuited. This helps lower the Q of the coil and thus reduces sparking at the driver contact. (http://members. iinet.net. au/~cool386/msp/ msp.html) looked fine, but substituting another speaker fixed it, so obviously the first substitute was no good. I guess that goes to show that you should test replacement parts before fitting them! Systematically working through the RF section brought me a relatively quick reward. The ECH35 stage was working fine; injecting a 455kHz signal modulated with 400Hz audio to the second 1M5 produced audible output, but there was no result when a signal was injected to the first 1M5. Finally, I found the last fault – the first 1M5 had only 1V across the filament, so it was effectively dead. The 1M5 data sheet states that the filament current is 0.12A at 2V. Using Ohm’s Law, that tells us the filament should have a resistance of 16.6W, precisely the value of series resistor R46 installed by Kriesler to reduce the 4V down to 2V. Testing the valve from this radio on the bench showed 0.2A of filament current at 2V (ie, 10W resistance). So I paralleled the 16.6W series resistor with a 22W resistor to restore 2V across the filament. Subsequently, I installed a new 1M5 valve meeting the original specification and then removed the 22W resistor. Finishing it up The radio now functioned perfectly. I put some parts together to create a dedicated 150V/6V DC mains power supply (shown below). When I started using this, I found that its two-core mains cord was radiating noise into the radio. I replaced it with a threecore lead with the Earth connected through to the radio, which then suppressed this EMI. The cabinet polished up remarkably well. So, in the end, this ugly duckling became an interesting addition to my collection. SC The custom 150V/6V DC power supply made for the Kriesler 31-2. siliconchip.com.au Australia’s electronics magazine September 2019  119 SILICON CHIP .com.au/shop ONLINESHOP Looking for a specialised component to build that latest and greatest Silicon Chip project? Maybe it’s the PCB you’re after? Or a pre-programmed micro? Or some other hard-to-get “bit”? The chances are they are available direct from the Silicon Chip Online Shop. • • • • • PCBs are normally IN STOCK and ready for despatch when that month’s magazine goes on sale (you don’t have to wait for them to be made!). Even if stock runs out (eg, for high demand), in most cases there will be no longer than a two-week wait. One low p&p charge: $10 per order, irregardless of how many items you order! (AUS only; overseas clients – check the website for a postage quote). Our PCBs are beautifully made, very high quality fibreglass boards with pre-tinned tracks, silk screen overlays and where applicable, solder masks. Best of all, subscribers receive a 10% discount on purchases! (Excluding subscription renewals and postage costs) HOW TO ORDER: INTERNET (24 hours, 7 days): log on to our secure website – siliconchip.com.au, click on “SHOP” and follow the links EMAIL – email silicon<at>siliconchip.com.au – Clearly tell us what you want and include your contact and credit card details MAIL – PO Box 139, Collaroy NSW 2097. Clearly tell us what you want and include your contact and credit card details PHONE (9am-5pm AET, Mon-Fri): Call (02) 9939 3295 (INT +612 9939 3295) – have your order ready, including contact and payment details! YES! You can also order or renew your SILICON CHIP subscription via any of these methods as well! 4 4 4 4 PRE-PROGRAMMED MICROS ATtiny816 PIC12F202-E/OT PIC12F617-I/P PIC12F675-I/P PIC12F675-E/P PIC16F1455-I/P PIC16F88-E/P PIC16F88-I/P PIC16LF88-I/P Micros cost from $10.00 to $20.00 each + $10 p&p per order# $10 MICROS ATtiny816 Development/Breakout Board (Jan19) ATmega328P Ultrabrite LED Driver (with free TC6502P095VCT IC, Sept19) PIC16F1459-I/SO Temperature Switch Mk2 (June18), Recurring Event Reminder (Jul18) PIC16F84A-20I/P Door Alarm (Aug18), Steam Whistle (Sept18) White Noise (Sept/Nov18) Remote Control Dimmer (Feb19), Steering Wheel Control IR Adaptor (Jun19) PIC16F877A-I/P Car Radio Dimmer Adaptor / Voltage Interceptor (Aug19) PIC32MM0256GPM028-I/SS IR-to-UHF Converter (Jul13), UHF-to-IR Converter (Jul13) PIC32MX170F256D-501P/T PC Birdies *2 chips – $15 pair* (Aug13), Driveway Monitor Receiver (July15) PIC32MX170F256B-50I/SP Hotel Safe Alarm (Jun16), 50A Battery Charger Controller (Nov16) Kelvin the Cricket (Oct17), Triac-based Mains Motor Speed Controller (Mar18) Heater Controller (Apr18), Useless Box IC3 (Dec18) Courtesy LED Light Delay for Cars (Oct14), Fan Speed Controller (Jan18) Microbridge & BackPack V2 / V3 (May17 / Aug19), USB Flexitimer (June18) Digital Interface Module (Nov18), GPS Speedo/Clock/Volume Control (Jun19) PIC32MX270F256B-50I/SP Auto Headlight Controller (Oct13), 10A 230V Motor Speed Controller (Feb14) PIC32MX795F512H-80I/PT Automotive Sensor Modifier (Dec16) Projector Speed (Apr11), Vox (Jun11), Ultrasonic Water Tank Level (Sep11) Quizzical (Oct11), Ultra LD Preamp (Nov11), 10-Channel Remote Control PIC32MX470F512H-I/PT Receiver (Jun13), Revised 10-Channel Remote Control Receiver (Jul13) Nicad/NiMH Burp Charger (Mar14), Remote Mains Timer (Nov14) Driveway Monitor Transmitter (July15), Fingerprint Scanner (Nov15) MPPT Lighting Charge Controller (Feb16), 50/60Hz Turntable Driver (May16) Cyclic Pump Timer (Sep16), 60V 40A DC Motor Speed Controller (Jan17) Pool Lap Counter (Mar17), Rapidbrake (Jul17), Deluxe Frequency Switch (May18) Useless Box IC1 (Dec18), Remote-controlled Preamp with Tone Control (Mar19) UHF Repeater (May19), Six Input Audio Selector (TWO VERSIONS, Sept19) Garbage Reminder (Jan13), Bellbird (Dec13), GPS Analog Clock Driver (Feb17) PIC32MX470F512H-120/PT PIC32MX470F512L-120/PT dsPIC33FJ128GP802-I/SP PIC32MZ2048EFH064-I/PT $15 MICROS RF Signal Generator (Jun/Jul19) Four-Channel DC Fan & Pump Controller (Dec18) Programmable Ignition Timing Module (Jun99), Fuel Mixture Display (Sept00) Oscar Noughts And Crosses (Oct07), UV Lightbox Timer (Nov07) 6-Digit GPS Clock (May-Jun09), 16-bit Digital Pot (Jul10), Semtest (Feb-May12) Super Digital Sound Effects (Aug18) 44-pin Micromite Mk2 (Aug14), 4DoF Simulation Seat (Sept19) Micromite Mk2 (Jan15) + 47F, Low Frequency Distortion Analyser (Apr15) Micromite LCD BackPack [either version] (Feb16), GPS Boat Computer (Apr16) Micromite Super Clock (Jul16), Touchscreen Voltage/Current Ref (Oct-Dec16) Micromite LCD BackPack V2 / V3 (May17 / Aug19), Deluxe eFuse (Aug17) Micromite DDS for IF Alignment (Sept17), Tariff Clock (Jul18) GPS-Synched Frequency Reference (Nov18) ASCII Video Terminal (Jul14), USB Mouse & Keyboard Adaptor (Feb19) Maximite (Mar11), miniMaximite (Nov11), Colour Maximite (Sept/Oct12) Touchscreen Audio Recorder (Jun/Jul 14) $20 MICROS Stereo Audio Delay/DSP (Nov13), Stereo Echo/Reverb (Feb 14) Digital Effects Unit (Oct14) Micromite PLUS Explore 64 (Aug 16), Micromite Plus LCD BackPack (Nov16) Micromite PLUS Explore 100 (Sep-Oct16) Digital Audio Signal Generator (Mar-May10), Digital Lighting Cont. (Oct-Dec10) SportSync (May11), Digital Audio Delay (Dec11) Quizzical (Oct11), Ultra-LD Preamp (Nov11), LED Musicolor (Nov12) $30 MICROS DSP Crossover/Equaliser (May19) SPECIALISED COMPONENTS, HARD-TO-GET BITS, ETC MICROMITE EXPLORE-28 (CAT SC5121) (SEPT 19) Complete kit – includes PCB plus programmed micros and all other onboard parts $30.00 Programmed micro bundle – PIC32MX170F256B-50I/SO + PIC16F1455-I/SL $20.00 MICROMITE LCD BACKPACK V3 (CAT SC5082) (AUG 19) KIT – includes PCB, programmed micros, 3.5in touchscreen LCD, laser-cut UB3 lid, mounting hardware, SMD Mosfets for PWM backlight control and all other mandatory on-board parts Separate/Optional Components: - 3.5-inch TFT LCD touchscreen (Cat SC5062) - DHT22 temp/humidity sensor (Cat SC4150) - BMP180 (Cat SC4343) OR BMP280 (Cat SC4595) temperature/pressure sensor - BME280 temperature/pressure/humidity sensor (Cat SC4608) - DS3231 real-time clock SOIC-16 IC (Cat SC5103) - 23LC1024 1MB RAM (SOIC-8) (Cat SC5104) - AT25SF041 512KB flash (SOIC-8) (Cat SC5105) - 10µF 16V X7R through-hole capacitor (Cat SC5106) GPS SPEEDO/CLOCK/VOLUME CONTROL 1.3-inch 128x64 SSD1306-based blue OLED display module (Cat SC5026) laser-cut matte black acrylic case pieces (Cat SC4987) MCP4251-502E/P dual-digital potentiometer (Cat SC5052) (JUN 19) $75.00 $30.00 $7.50 $5.00 $10.00 $3.00 $5.00 $1.50 $2.00 $15.00 $10.00 $3.00 (FEB 19) N-channel Mosfets Q1 & Q2 (SIHB15N60E) and two 4.7MW 3.5kV resistors (Cat SC4861) $20.00 IRD1 (TSOP4136) and fresnel lens (IML0688) (Cat SC4862) $10.00 MOTION SENSING SWITCH (SMD VERSION) (FEB 19) Short form kit (includes PCB and all parts, except for the extension cable) (Cat SC4851) $10.00 SW-18010P vibration sensor (S1) (Cat SC4852) $1.00 (JAN 19) Main PCB with IC1 pre-soldered Main PCB with IC1 and surrounding components (white box at top right) pre-soldered Explore 100 kit (Cat SC3834; no LCD included) Laser-cut clear acrylic case pieces Set of extra SMD parts (contains most SMD parts except for the digital audio output) Extendable VHF whip antenna with SMA connector: 700mm ($15.00) and 465mm ($10.00) PCB-mounting SMA ($2.50), PAL ($5.00) and dual-horizontal RCA ($2.50) socket (AUG 18) PCB and all onboard parts (including optional ones) but no SD card, cell or battery holder $40.00 USB PORT PROTECTOR COMPLETE KIT (CAT SC4574) (MAY 18) PARTS FOR THE 6GHz+ TOUCHSCREEN FREQUENCY COUNTER (OCT 17) All parts including the PCB and a length of clear heatshrink tubing TOUCH & IR REMOTE CONTROL DIMMER DAB+/FM/AM RADIO P&P – $10 Per order# SUPER DIGITAL SOUND EFFECTS KIT (CAT SC4658) $60.00 $80.00 $69.90 $20.00 $30.00 Explore 100 kit (Cat SC3834; no LCD included) One ERA-2SM+ & one ADCH-80A+ (Cat SC1167; two required) $15.00 $69.90 $15.00/pk. MICROBRIDGE COMPLETE KIT (CAT SC4264) (MAY 17) PCB plus all on-board parts including programmed microcontroller (SMD ceramics for 10µF) $20.00 STATIONMASTER (CAT SC4187) (MAR 17) Hard to get parts: DRV8871 IC, SMD 1µF capacitor and 100kW potentiometer with detent $12.50 VARIOUS MODULES & PARTS - ISD1820-based voice recorder / playback module (Junk Mail Repeller, AUG19) $4.00 - 23LCV1024-I/P SRAM (DIP) and MCP73831T charger ICs (UHF Repeater, MAY19) $11.50 - MCP1700 3.3V LDO regulator (suitable for USB Mouse & Keyboard Adapator, FEB19) $1.50 - LM4865MX amplifier IC & LF50CV regulator (Tinnitus/Insomnia Killer, NOV18) $10.00 - 2.8-inch touchscreen LCD module with SD card socket (Tide Clock, JUL18) $22.50 - ESP-01 WiFi Module (El Cheapo Modules, Part 15, APR18) $5.00 - MC1496P double-balanced mixer IC (DIP-14) (AM Radio Transmitter, MAR18) $2.50 - WiFi Antennas with U.FL/IPX connectors (Water Tank Level Meter with WiFi, FEB18): 5dBi – $12.50 ~ 2dBi (omnidirectional) – $10.00 - NRF24L01+PA+NA transceiver with SNA connector and antenna (El Cheapo 12, JAN18) $5.00 - WeMos D1 Arduino-compatible boards with WiFi (SEPT17, FEB18): ThingSpeak data logger – $10.00 ~ WiFi Tank Level Meter (ext. antenna socket) – $15.00 - Geeetech Arduino MP3 shield (Arduino Music Player/Recorder, VS1053, JUL17) $20.00 - 1nF 1% MKP (5mm lead spacing) or ceramic capacitor (Wide-Range LC Meter, JUN18) $2.50 - MAX7219 LED controller boards (El Cheapo Modules, Part 7, JUN17): 8x8 red SMD/DIP matrix display – $5.00 ~ red 8-digit 7-segment display – $7.50 - AD9833 DDS module (with gain control) (for Micromite DDS, APR17) $25.00 - AD9833 DDS module (no gain control) (El Cheapo Modules, Part 6, APR17) $15.00 - CP2102 USB-UART bridge $5.00 - microSD card adaptor (El Cheapo Modules, Part 3, JAN17) $2.50 - DS3231 real-time clock module with mounting spacers and screws (El Cheapo, OCT16) $5.00 THESE ARE ONLY THE MOST RECENT MICROS AND SPECIALISED COMPONENTS. FOR THE FULL LIST, SEE www.siliconchip.com.au/shop *Prices valid for month of magazine issue only. All prices in Australian dollars and include GST where applicable. # P&P prices are within Australia. O’seas? Place an order on our website for an accurate quote. 09/19 PRINTED CIRCUIT BOARDS NOTE: The listings below are for the PCB ONLY. If you want a kit, check our store or contact the kit suppliers advertising in this issue. For unusual projects where kits are not available, some have specialised components available – see the list opposite. NOTE: Not all PCBs are shown here due to space limits but the Silicon Chip Online Shop has boards going back to 2001 and beyond. For a complete list of available PCBs etc, go to siliconchip.com.au/shop/8 Prices are PCBs only, NOT COMPLETE KITS! PRINTED CIRCUIT BOARD TO SUIT PROJECT: PUBLISHED: APPLIANCE INSULATION TESTER APR 2015 APPLIANCE INSULATION TESTER FRONT PANEL APR 2015 APPLIANCE EARTH LEAKAGE TESTER PCBs (2) MAY 2015 APPLIANCE EARTH LEAKAGE TESTER LID/PANEL MAY 2015 4-OUTPUT UNIVERSAL ADJUSTABLE REGULATOR MAY 2015 SIGNAL INJECTOR & TRACER JUNE 2015 PASSIVE RF PROBE JUNE 2015 SIGNAL INJECTOR & TRACER SHIELD JUNE 2015 BAD VIBES INFRASOUND SNOOPER JUNE 2015 CHAMPION + PRE-CHAMPION JUNE 2015 DRIVEWAY MONITOR TRANSMITTER PCB JULY 2015 DRIVEWAY MONITOR RECEIVER PCB JULY 2015 MINI USB SWITCHMODE REGULATOR JULY 2015 VOLTAGE/RESISTANCE/CURRENT REFERENCE AUG 2015 LED PARTY STROBE MK2 AUG 2015 ULTRA-LD MK4 200W AMPLIFIER MODULE SEP 2015 9-CHANNEL REMOTE CONTROL RECEIVER SEP 2015 MINI USB SWITCHMODE REGULATOR MK2 SEP 2015 2-WAY PASSIVE LOUDSPEAKER CROSSOVER OCT 2015 ULTRA LD AMPLIFIER POWER SUPPLY OCT 2015 ARDUINO USB ELECTROCARDIOGRAPH OCT 2015 FINGERPRINT SCANNER – SET OF TWO PCBS NOV 2015 LOUDSPEAKER PROTECTOR NOV 2015 LED CLOCK DEC 2015 SPEECH TIMER DEC 2015 TURNTABLE STROBE DEC 2015 CALIBRATED TURNTABLE STROBOSCOPE ETCHED DISC DEC 2015 VALVE STEREO PREAMPLIFIER – PCB JAN 2016 VALVE STEREO PREAMPLIFIER – CASE PARTS JAN 2016 QUICKBRAKE BRAKE LIGHT SPEEDUP JAN 2016 SOLAR MPPT CHARGER & LIGHTING CONTROLLER FEB/MAR 2016 MICROMITE LCD BACKPACK, 2.4-INCH VERSION FEB/MAR 2016 MICROMITE LCD BACKPACK, 2.8-INCH VERSION FEB/MAR 2016 BATTERY CELL BALANCER MAR 2016 DELTA THROTTLE TIMER MAR 2016 MICROWAVE LEAKAGE DETECTOR APR 2016 FRIDGE/FREEZER ALARM APR 2016 ARDUINO MULTIFUNCTION MEASUREMENT APR 2016 PRECISION 50/60Hz TURNTABLE DRIVER MAY 2016 RASPBERRY PI TEMP SENSOR EXPANSION MAY 2016 100DB STEREO AUDIO LEVEL/VU METER JUN 2016 HOTEL SAFE ALARM JUN 2016 UNIVERSAL TEMPERATURE ALARM JULY 2016 BROWNOUT PROTECTOR MK2 JULY 2016 8-DIGIT FREQUENCY METER AUG 2016 APPLIANCE ENERGY METER AUG 2016 MICROMITE PLUS EXPLORE 64 AUG 2016 CYCLIC PUMP/MAINS TIMER SEPT 2016 MICROMITE PLUS EXPLORE 100 (4 layer) SEPT 2016 AUTOMOTIVE FAULT DETECTOR SEPT 2016 MOSQUITO LURE OCT 2016 MICROPOWER LED FLASHER OCT 2016 MINI MICROPOWER LED FLASHER OCT 2016 50A BATTERY CHARGER CONTROLLER NOV 2016 PASSIVE LINE TO PHONO INPUT CONVERTER NOV 2016 MICROMITE PLUS LCD BACKPACK NOV 2016 AUTOMOTIVE SENSOR MODIFIER DEC 2016 TOUCHSCREEN VOLTAGE/CURRENT REFERENCE DEC 2016 SC200 AMPLIFIER MODULE JAN 2017 60V 40A DC MOTOR SPEED CON. CONTROL BOARD JAN 2017 60V 40A DC MOTOR SPEED CON. MOSFET BOARD JAN 2017 GPS SYNCHRONISED ANALOG CLOCK FEB 2017 ULTRA LOW VOLTAGE LED FLASHER FEB 2017 POOL LAP COUNTER MAR 2017 STATIONMASTER TRAIN CONTROLLER MAR 2017 EFUSE APR 2017 SPRING REVERB APR 2017 6GHz+ 1000:1 PRESCALER MAY 2017 MICROBRIDGE MAY 2017 MICROMITE LCD BACKPACK V2 MAY 2017 10-OCTAVE STEREO GRAPHIC EQUALISER PCB JUN 2017 10-OCTAVE STEREO GRAPHIC EQUALISER FRONT PANEL JUN 2017 10-OCTAVE STEREO GRAPHIC EQUALISER CASE PIECES JUN 2017 RAPIDBRAKE JUL 2017 DELUXE EFUSE AUG 2017 DELUXE EFUSE UB1 LID AUG 2017 MAINS SUPPLY FOR BATTERY VALVES (INC. PANELS) AUG 2017 3-WAY ADJUSTABLE ACTIVE CROSSOVER SEPT 2017 3-WAY ADJUSTABLE ACTIVE CROSSOVER PANELS SEPT 2017 3-WAY ADJUSTABLE ACTIVE CROSSOVER CASE PIECES SEPT 2017 6GHz+ TOUCHSCREEN FREQUENCY COUNTER OCT 2017 KELVIN THE CRICKET OCT 2017 PCB CODE: 04103151 04103152 04203151/2 04203153 18105151 04106151 04106152 04106153 04104151 01109121/2 15105151 15105152 18107151 04108151 16101141 01107151 15108151 18107152 01205141 01109111 07108151 03109151/2 01110151 19110151 19111151 04101161 04101162 01101161 01101162 05102161 16101161 07102121 07102122 11111151 05102161 04103161 03104161 04116011/2 04104161 24104161 01104161 03106161 03105161 10107161 04105161 04116061 07108161 10108161/2 07109161 05109161 25110161 16109161 16109162 11111161 01111161 07110161 05111161 04110161 01108161 11112161 11112162 04202171 16110161 19102171 09103171/2 04102171 01104171 04112162 24104171 07104171 01105171 01105172 SC4281 05105171 18106171 SC4316 18108171-4 01108171 01108172/3 SC4403 04110171 08109171 Price: $10.00 $10.00 $15.00 $15.00 $5.00 $7.50 $2.50 $5.00 $5.00 $7.50 $10.00 $5.00 $2.50 $2.50 $7.50 $15.00 $15.00 $2.50 $20.00 $15.00 $7.50 $15.00 $10.00 $15.00 $15.00 $5.00 $10.00 $15.00 $20.00 $15.00 $15.00 $7.50 $7.50 $6.00 $15.00 $5.00 $5.00 $15.00 $15.00 $5.00 $15.00 $5.00 $5.00 $10.00 $10.00 $15.00 $5.00 $10.00/pair $20.00 $10.00 $5.00 $5.00 $2.50 $10.00 $5.00 $7.50 $10.00 $12.50 $10.00 $10.00 $12.50 $10.00 $2.50 $15.00 $15.00/set $7.50 $12.50 $7.50 $2.50 $7.50 $12.50 $15.00 $15.00 $10.00 $15.00 $5.00 $25.00 $20.00 $20.00/pair $10.00 $10.00 $10.00 PRINTED CIRCUIT BOARD TO SUIT PROJECT: PUBLISHED: PCB CODE: 6GHz+ FREQUENCY COUNTER CASE PIECES (SET) SUPER-7 SUPERHET AM RADIO PCB SUPER-7 SUPERHET AM RADIO CASE PIECES THEREMIN PROPORTIONAL FAN SPEED CONTROLLER WATER TANK LEVEL METER (INCLUDING HEADERS) 10-LED BARAGRAPH 10-LED BARAGRAPH SIGNAL PROCESSING TRIAC-BASED MAINS MOTOR SPEED CONTROLLER VINTAGE TV A/V MODULATOR AM RADIO TRANSMITTER HEATER CONTROLLER DELUXE FREQUENCY SWITCH USB PORT PROTECTOR 2 x 12V BATTERY BALANCER USB FLEXITIMER WIDE-RANGE LC METER WIDE-RANGE LC METER (INCLUDING HEADERS) WIDE-RANGE LC METER CLEAR CASE PIECES TEMPERATURE SWITCH MK2 LiFePO4 UPS CONTROL SHIELD RASPBERRY PI TOUCHSCREEN ADAPTOR (TIDE CLOCK) RECURRING EVENT REMINDER BRAINWAVE MONITOR (EEG) SUPER DIGITAL SOUND EFFECTS DOOR ALARM STEAM WHISTLE / DIESEL HORN DCC PROGRAMMER DCC PROGRAMMER (INCLUDING HEADERS) OPTO-ISOLATED RELAY (WITH EXTENSION BOARDS) GPS-SYNCHED FREQUENCY REFERENCE LED CHRISTMAS TREE DIGITAL INTERFACE MODULE TINNITUS/INSOMNIA KILLER (JAYCAR VERSION) TINNITUS/INSOMNIA KILLER (ALTRONICS VERSION) HIGH-SENSITIVITY MAGNETOMETER USELESS BOX FOUR-CHANNEL DC FAN & PUMP CONTROLLER ATtiny816 DEVELOPMENT/BREAKOUT BOARD ISOLATED SERIAL LINK DAB+/FM/AM RADIO TOUCH & IR REMOTE CONTROL DIMMER MAIN PCB REMOTE CONTROL DIMMER MOUNTING PLATE REMOTE CONTROL DIMMER EXTENSION PCB MOTION SENSING SWITCH (SMD) PCB USB MOUSE AND KEYBOARD ADAPTOR PCB REMOTE-CONTROLLED PREAMP WITH TONE CONTROL PREAMP INPUT SELECTOR BOARD PREAMP PUSHBUTTON BOARD DIODE CURVE PLOTTER FLIP-DOT COIL FLIP-DOT PIXEL (INCLUDES 16 PIXELS) FLIP-DOT FRAME (INCLUDES 8 FRAMES) FLIP-DOT DRIVER FLIP-DOT (SET OF ALL FOUR PCBS) iCESTICK VGA ADAPTOR UHF DATA REPEATER AMPLIFIER BRIDGE ADAPTOR 3.5-INCH SERIAL LCD ADAPTOR FOR ARDUINO DSP CROSSOVER/EQUALISER ADC BOARD DSP CROSSOVER/EQUALISER DAC BOARD DSP CROSSOVER/EQUALISER CPU BOARD DSP CROSSOVER/EQUALISER PSU BOARD DSP CROSSOVER/EQUALISER CONTROL BOARD DSP CROSSOVER/EQUALISER LCD ADAPTOR DSP CROSSOVER (SET OF ALL BOARDS – TWO DAC) STEERING WHEEL CONTROL IR ADAPTOR GPS SPEEDO/CLOCK/VOLUME CONTROL RF SIGNAL GENERATOR RASPBERRY PI SPEECH SYNTHESIS/AUDIO BATTERY ISOLATOR CONTROL BOARD BATTERY ISOLATOR MOSFET BOARD (2oz) MICROMITE LCD BACKPACK V3 CAR RADIO DIMMER ADAPTOR/VOLTAGE INTERCEPTOR PSEUDO-RANDOM NUMBER GENERATOR (LFSR) DEC 2017 DEC 2017 DEC 2017 JAN 2018 JAN 2018 FEB 2018 FEB 2018 FEB 2018 MAR 2018 MAR 2018 MAR 2018 APR 2018 MAY 2018 MAY 2018 MAY 2018 JUNE 2018 JUNE 2018 JUNE 2018 JUNE 2018 JUNE 2018 JUNE 2018 JULY 2018 JULY 2018 AUG 2018 AUG 2018 AUG 2018 SEPT 2018 OCT 2018 OCT 2018 OCT 2018 NOV 2018 NOV 2018 NOV 2018 NOV 2018 NOV 2018 DEC 2018 DEC 2018 DEC 2018 JAN 2019 JAN 2019 JAN 2019 FEB 2019 FEB 2019 FEB 2019 FEB 2019 FEB 2019 MAR 2019 MAR 2019 MAR 2019 MAR 2019 APR 2019 APR 2019 APR 2019 APR 2019 APR 2019 APR 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 JUNE 2019 JUNE 2019 JUNE 2019 JULY 2019 JULY 2019 JULY 2019 AUG 2019 AUG 2019 AUG 2019 SC4444 06111171 SC4464 23112171 05111171 21110171 04101181 04101182 10102181 02104181 06101181 10104181 05104181 07105181 14106181 19106181 04106181 SC4618 SC4609 05105181 11106181 24108181 19107181 25107181 01107181 03107181 09106181 09107181 09107181 10107181/2 04107181 16107181 16107182 01110181 01110182 04101011 08111181 05108181 24110181 24107181 06112181 10111191 10111192 10111193 05102191 24311181 01111119 01111112 01111113 04112181 19111181 19111182 19111183 19111184 SC4950 02103191 15004191 01105191 24111181 01106191 01106192 01106193 01106194 01106195 01106196 SC5023 05105191 01104191 04106191 01106191 05106191 05106192 07106191 05107191 16106191 4DoF SIMULATION SEAT CONTROLLER BOARD HIGH-CURRENT H-BRIDGE MOTOR DRIVER MICROMITE EXPLORE-28 (4-LAYERS) SIX INPUT AUDIO SELECTOR MAIN BOARD SIX INPUT AUDIO SELECTOR PUSHBUTTON BOARD ULTRABRITE LED DRIVER SEPT 2019 SEPT 2019 SEPT 2019 SEPT 2019 SEPT 2019 SEPT 2019 11109191 11109192 07108191 01110191 01110192 16109191 NEW PCBs Price: $15.00 $25.00 $25.00 $12.50 $2.50 $7.50 $7.50 $5.00 $10.00 $7.50 $7.50 $10.00 $7.50 $2.50 $2.50 $7.50 $5.00 $7.50 $7.50 $7.50 $5.00 $5.00 $5.00 $10.00 $2.50 $5.00 $5.00 $5.00 $7.50 $7.50 $7.50 $5.00 $2.50 $5.00 $5.00 $12.50 $7.50 $5.00 $5.00 $5.00 $15.00 $10.00 $10.00 $10.00 $2.50 $5.00 $25.00 $15.00 $5.00 $7.50 $5.00 $5.00 $5.00 $5.00 $17.50 $2.50 $10.00 $5.00 $5.00 $7.50 $7.50 $5.00 $7.50 $5.00 $2.50 $40.00 $5.00 $7.50 $15.00 $5.00 $7.50 $10.00 $7.50 $5.00 $5.00 $7.50 $2.50 $5.00 $7.50 $5.00 $2.50 WE ALSO SELL AN A2 REACTANCE WALLCHART, RTV&H DVD, VINTAGE RADIO DVD PLUS VARIOUS BOOKs IN THE “Books, DVDs, etc” PAGE AT SILICONCHIP.COM.AU/SHOP/3 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Send your email to silicon<at>siliconchip.com.au Ultracaps: an expensive way to store energy I don’t know if it would be worth publishing a project article on the subject, but a battery made of supercapacitors sounds interesting. How about an automotive 12V battery or a battery to be used in a home solar panel system to store energy? It may be just too expensive, but could it be an option in certain circumstances? Thanks for a great magazine. (F. C., Maroubra, NSW) • Jaycar used to sell 12V supercapacitors for car amplifier use, but they don’t stock them any more. However, supercapacitor/ultracapacitor banks are available online, for example: www.aliexpress.com/ item/33019886354.html The problem is that the energy storage of a supercapacitor is a lot less than a battery; even if you’re willing to spend a lot of money on capacitors, it’s hard to overcome that. Especially when you consider that lead-acid replacement LiFePO4 batteries are now becoming widely available at fairly reasonable prices (see Jaycar’s latest catalog). To illustrate our point, the 16V 83F capacitor bank linked above has a maximum energy storage of 10.6kJ (C × V2 ÷ 2; 83 × 162 ÷ 2). The energy storage of a 7.2Ah 12V SLA, costing less than half as much ($20 retail) is 311kJ (12V × 7.2Ah × 3600s), or 30 times as much. It’s also easier to extract the energy from a battery since its voltage only varies over a range of about 11-13V during discharge, while the capacitor bank has to be charged up to 16V and discharged to 0V to use all of its energy storage capability. EHT probe voltage rating and bandwidth I recently bought a back issue copy of the April 2010 issue as I wanted to build the 1000:1 EHT probe (siliconchip.com.au/Article/121) to measure the ignition voltage on au122 Silicon Chip tomotive coils (many kilovolts), both CDI and TCI type. I have two questions about this design. Firstly, how did you arrive at the 25kV maximum rating? I foresee it handling 30kV or maybe even more, and am curious whether this EHT probe can be used in that range. I want to measure a spike which might last only a few milliseconds at most, so will not be using a DMM but an oscilloscope. Secondly, your calibration voltage trimpot leg confuses me a bit. You refer to trimming the leg to 800.8kW but even with VR1 at zero, the fixed values of 820kW and 30kW already total 850kW. So how can that leg be trimmed down to 800.8kW with the trimpot in series with those resistors? (N. M., Northern Ireland) • The maximum voltage that the 1000:1 EHT probe can handle is limited not by the resistor voltage or power ratings, but by the distance between each group of resistors on the PCB. Each resistor is rated at 1.6kV, but that doesn’t mean you can apply 1.6kV × 80 = 128kV to the probe without any problems. You will get flashover across the exposed pads on the PCB. From the 12.7mm (0.5in) spacing between each resistor group, we can calculate that it should be safe from flashover with about 2.5kV between each group, so with 10 groups, that gives us our total rating of 25kV. This is slightly conservative, as you could probably apply a few more kV before arcover occurred, considering that there is extra spacing for the resistors at the probe end. But 30kV would be pushing it; whether it could handle that would depend on the humidity, your altitude, how clean the PCB is etc. To calculate the maximum voltage rating based on the distance between conductors, see the following website: www.smpspowersupply.com/ ipc2221pcbclearance.html To answer your second question, you have to remember that the DMM’s input impedance of 10MW is in parallel with the bottom leg of the diAustralia’s electronics magazine vider, so to achieve a total resistance of 800.8kW, the resistance in the EHT Probe needs to be 870.51kW (1 ÷ [1 ÷ 800.8kW - 1 ÷ 10MW]). Since the fixed resistors total 850kW, VR1 is adjusted for about 20.51kW, which is near the halfway point. Since most scopes have a 1MW input impedance, you will need to change the bottom leg divider resistors to 3.9MW and 68kW and VR1 to 100kW, to allow you to adjust the total resistance to 4.02MW, which in combination with the 1MW input impedance, gives you the same 800.8kW total resistance. However, we think you are going to run into difficulty measuring short pulses with the modified probe. The reason is the scope’s non-trivial input capacitance, which will be around 12pF. This will form a low-pass filter with the probe’s considerable resistance, and also a capacitive divider with the probe’s parasitic capacitance. Depending on which effect is stronger, you will either get a roll-off in the frequency response that could seriously smooth and attenuate the pulses you are trying to measure, or overshoot and ringing. We suspect that the low-pass filter formed from the 800MW and ~12pF, giving a -3dB point of around 16.5Hz, will be the dominant effect. To overcome this, you need to measure the modified probe’s frequency response to determine its -3dB point, then use that figure to calculate the parasitic capacitance across the resistors. You can then figure out how much total capacitance to add, to compensate the probe and give a flatter frequency response – it would need to extend to at least a few kilohertz if you are looking at millisecond-level pulses, and ideally higher. The only practical way to add this capacitance would be to connect highvoltage, low-value (0.1-1pF) capacitors across groups of resistors. Unfortunately, it’s difficult to find throughhole capacitors with such values and ratings. You may need to solder SMD siliconchip.com.au capacitors to a resistor pad at one end and a short length of insulated wire at the other end, to reach the next resistor group. These modifications will not be easy but they should be possible, and you will end up with a high-voltage probe with sufficient bandwidth for your purposes, if you take the time to get it right. Ultrasonic Anti-Fouling with a 24V battery I am planning to install an ultrasonic anti-fouling system in our sailing vessel, such as your design from the May & June 2017 issues (siliconchip.com. au/Series/312), which I plan to build from a Jaycar kit (Cat KC5535). But before ordering it, I have some questions. Our boat has a 24V battery system. Is there a kit that can run from this voltage? Also, our boat is a lifting keel type. The ballast in the hull is made from concrete. Will that cause any problems? It is 39 feet (12m) long. Will two ultrasonic transducers be sufficient, and where should we install them? (P. V., via email) • All of our Ultrasonic Anti-fouling units are designed for 12V battery operation only. You could run them from a 24V battery system, but you would need a device to step the voltage down from 24V to 12V that can supply at least 4A. Jaycar Cat MP3356 (5A 24V-12V DC-DC Converter with USB Charger) should be suitable. Ultrasonic anti-fouling is most effective while the boat is at rest, so the keel lifting when the boat is moving will not affect the operation of the antifouling system. The unit will work with concrete hulls. The best place to find details on how and where to install the transducers is in our September and November 2010 issues, in the articles on our original Ultrasonic Anti-Fouling system (siliconchip.com.au/Series/12). Those magazines are available as back-issues, or you can purchase online access via our website. Anti-Fouling transducer potting is damaged I finally found time to finish building your 2017 Ultrasonic Anti-Fouling kit from a Jaycar kit (Cat KC5535). I am getting ready to install it on my boat, but I have two questions. siliconchip.com.au Firstly, as I was at the point of screwing in the flanged nut, I started removing what appeared like a protective paper on the transducer. I then stopped as the glue seemed quite permanent. Should these paper covers be removed? If not, what should I do now? Can I use glue to re-attach the torn part of the paper? Also, I want like to try different positions on the hull to install the transducers and may later move the system to another boat if I ever decide to buy a new one. Can you supply extra flanged nuts and J-B Weld two-part epoxy glue for attaching them? (C. B., France) • The ‘protective paper’ you have started to pull off is the potting compound used to seal the transducer within the plastic housing. This should be re-potted using a smear of the mixed J-B Weld two-part epoxy beneath the lifted section. Having applied the epoxy, press down on the lifted section to remove any air pockets and ensure it is held flat for 24 hours, to allow the epoxy to cure fully. We do not sell the J-B Weld epoxy or the 50mm BSP flanged back nuts. These should be available from hardware stores and plumbing suppliers. The flanged nuts can be found on eBay, for example: www.ebay.com/ itm//121940440567 (sent from the UK). J-B Weld can also be ordered online and found in many automotive parts stores. Alternatively, Jaycar sells J-B Weld (Cat NA1518; www.jaycar.com. au/j-b-weld-epoxy/p/NA1518). Speed controller for high-voltage DC motor I have a 500W, 220V DC motor (permanent magnet type) and would like to know if your March 2018 Full Wave, 230V Motor Speed Controller (siliconchip.com.au/Article/10998) could be used to control its speed. Would I have to add a rectifier circuit to convert its AC output to DC? (Dalibor, via email) • You would get a variable voltage DC waveform if you rectified the output of the Universal Motor Speed Controller, with the correct average voltage. But at higher settings, the peak output voltage would exceed the 220V DC rating of your motor and could go as high as 350V DC or even higher, depending on your mains voltage. That could lead to insulation breakdown in the motor, which could be a safeAustralia’s electronics magazine ty hazard and could also destroy the motor. So we do not recommend that you try this. We have not (yet) produced a motor speed controller suitable for a 220V DC motor, as is commonly found in treadmills. Speed controller for 100W fan I want to build the Deluxe 230VAC Fan Speed Controller (May 2014; siliconchip.com.au/Article/7595) to control a workshop dust cleaner which is rated at 100W (a Thor TF810 air filter). Could I use this circuit for that or would it need to be modified? (W. P., Curl Curl, NSW) • The 80W rating on that device is a conservative figure. Since a Mosfet connected in series with the motor provides speed control by varying its resistance, the circuit supplies a limited current which varies with the pot setting, thus offering inherent protection. This current limiting may mean that your fan will run more slowly for a given setting compared to a lower wattage fan. But it’s unlikely to cause damage, despite being rated at 100W. Currawong resistor burn-out I have finally built the Currawong Stereo Valve Amplifier (siliconchip. com.au/Series/277) and at present am in the power-up testing phase. I have used the ‘new’ power transformer (Altronics Cat MA5399) as mentioned in the October 2016 issue, and wired it accordingly, with LK6 installed. Before connecting the transformer to the PCB, I powered it up and measured 129V AC between pins 1 & 3 of CON7 and 13.8V AC between pins 1 & 3 and 4 & 5 of CON8. I then connected the transformer to the PCB but left all the valves out, and switched it on. The four blue LEDs adjacent to T3 & T4 lit immediately and brightly. The headphone LED2 was off, and power LED1 was on (red & bright) and turned green (bright also) roughly 20 seconds later. But approximately 2-3 seconds after power LED1 turned green, there was a ‘fizzing’ noise and a burning smell coming from the top of PCB. After removing power, I noticed that the 6.8kW 1W resistor next to the socket for V8 had burned out. September 2019  123 I checked all the component values and orientation. The +HT supply seems correct and I can’t find any shorts on either side of the PCB. If you have any thoughts/comments or require more information, please let me know. Thank you for your time. (S. B., Port Macquarie, NSW) • The 6.8kW resistor which burned out is the one shown directly above V3/V7 on the circuit diagram (Fig.1 on page 31 of the November 2014 issue). It’s part of the supply filtering for the amplifier front-end, powering preamplifier valves V5 and V6. If it burns out, that means there must be a short circuit somewhere in the front end. Since you left those valves out when you powered it up, that leaves only a few places where the short circuit could be. Immediate suspicion falls on the 39µF bypass capacitor which is connected between this resistor and ground, mounted near the front of the board, just above the Currawong logo. If that was reversed or faulty then it would explain the resistor burning out. The only other thing we can think of would be a short circuit between components on the board, possibly due to bridged solder joints, but you said you inspected the board and couldn’t find any shorts, and the pads and tracks on this board are spaced quite far apart. So that seems unlikely. There are no other obvious components which could cause this; the following 220kW, 120kW and 47kW resistors would burn out first if the short circuit was elsewhere. But we suggest that you check the value of all of those resistors anyway. The 47kW resistor in question is right below the 6.8kW resistor. The 120kW and 220kW resistors are just below LK5. If those all measure OK then we think it must be the aforementioned capacitor at fault. Currawong supply voltages a bit high I wrote to you previously about the Currawong valve amplifier I built (October 2014-January 2015; siliconchip. com.au/Series/277) where one of the resistors burned out after I powered it up (see above - Editor). As you suggested, I checked the 39µF filter capacitor. Its orientation was correct, but when removed, there was a small amount of electrolyte which had leaked out, making me think it was faulty. 124 Silicon Chip I replaced the capacitor and the 6.8kW resistor which had burned out and powered it up. The resistor did not burn out again, so I think the problem has been solved. However, some of the voltages I then measured on the board were higher than I expected. The power transformer is producing 131V AC on the main secondary and 13.8V AC on each of the other two. These are within a couple of volts of what is stated in the October 2016 issue. My concerns are the readings on the HT supply (before and after the filter) and the supply voltages at the valves and heater filaments. I get a reading of 15.03V DC between pins 4 & 5 of the 12AX7 sockets (ie, for the nominally 12V heaters). Then on the HT side, I read 360V DC at the cathode of D1, 358V DC on pin 3 of each 6L6 socket, 270V DC and 310V DC respectively on pins 1 and 6 of V1 and V5, and 318V DC and 292V DC respectively on pins 1 and 6 of V2 & V6. The HT supply is approximately 40V above the suggested HT supply in the article. I realise that this is when the supply is not under load, and that mains voltages can vary quite significantly from the nominal 230V AC. But I am concerned that these readings are still too high. The HT supply voltages to the 9-pin sockets at pins 1 & 6 seem on point on a couple of pins but quite low on others. (S. B., Port Macquarie, NSW) • 131V AC is significantly higher than the design figure of 110V AC but as you say, these readings are essentially unloaded. While your voltage readings are higher than expected, they are all well within the component ratings, so you should plug the valves in and recheck the voltages to see if they come down a bit. The ideal heater voltage for a 12AX7 is around 12.6V. Any lower and the performance suffers. Yours is quite high at 15V. A typical tolerance figure given is ±10%, which is a range of 11.34-13.86V. This will almost certainly drop into that range once the valves have been plugged in, but you should check that. 358V is a good deal higher than the 308V intended for the 6L6 anodes but is still well below their 500V maximum rating. And the other readings are below the 330V maximum plate rating of the 12AX7. Australia’s electronics magazine In a sense, slightly higher voltages in the Currawong are good – you will probably get more power from the amplifier. You will also have more dissipation, though, including when it is idle. That shouldn’t be a major problem, but we never tested the amplifier at elevated voltages. You should monitor the overall temperature during operation (don’t touch the output valves though!). Unless there is evidence of anything overheating, you should be OK. What is a little concerning, though, is the varying readings you get on pins 1 and 6 of V1, V2, V5 & V6. With those valves not in circuit, there should not be any path for current to flow in that part of the circuit, and so these pins should all be very close to the 358V DC readings you got at pin 3 of V3, V4, V7 & V8. What is your meter’s input impedance? If you’re using an old-style meter with an input impedance of 1MW, this will form a voltage divider with the anode and filter resistors, giving you artificially low readings. The readings you’ve given are low by almost precisely the amount you would expect for a 1MW input impedance. Try using a modern DMM with a 10MW input impedance and see if you get higher voltage readings on those pins. Can Studio 350 amp drive a 2W load? I have a few Studio 350 amplifier kits (January & February 2004; siliconchip.com.au/Series/97) left over from a project and was wondering whether I can operate them with a reduced supply voltage so I can use two of them to drive a 4W load in bridge mode. Each amplifier module would ‘see’ a 2W load in this configuration. (J. A., via email) • Reducing the supply rails considerably from the ±70V specified for the Studio 350 module would enable you to drive a 4W load in bridge mode. However, various biasing resistors would need changing so the amplifier transistors are operating along the correct load line. Overall, we think that you would be better off just using one amplifier module running off the full ±70V supply rails to drive the 4W load on its own, not in bridge mode. siliconchip.com.au Troubleshooting High Energy Ignition I recently built your High Energy Ignition System (November-December 2012; siliconchip.com.au/Series/18) from a kit – it’s for use on an older, points-based car. After making it up according to the directions, I was not getting any spark when the points opened. I did a fair bit of troubleshooting on the board. All the required components are soldered properly and are the correct value. There is a 5V output from the regulator and 5V at pin 14 of IC1 (Vdd). I can see an appropriate voltage at pin 13 of IC1, the battery voltage monitor. I can also vary the voltage on pin 18 by varying VR1, and at pin 1 by varying VR2. But even in Spark Test mode, there is no output on pin 9. Most of the time there is no voltage, but occasionally it goes to around 4.95V. I have tested Q1 with an Arduino delivering a 20Hz square wave, and if I connect it to a coil, I get sparks at 20Hz. The Arduino square wave output is very clear on my scope, but nothing is showing on pin 9 of IC1. While I don’t currently have a PIC programmer, it seems to me that the PIC is either not programmed properly or is faulty. Is this common? Do you have any other suggestions? (I. B., Wauchope, NSW) • If you have 5V at pins 4 and 14 of IC1 and 0V at pin 5, with the other voltages you mentioned being correct at pins 13, 1 and 18, the PIC should certainly be producing a waveform at pin 9 when in the spark test mode. Check that pin 9 is not shorted to ground somehow. If your Arduino test involved unplugging IC1 from its socket and feeding the waveform into pin 9, that shows there is no short. One way of testing that the PIC has been programmed correctly is to check the voltage at pins 11, 12 and 8 without the jumper links inserted. These pins should be pulled to 5V via internal pull-up current. If not, either the PIC is not programmed, or the crystal oscillator is not running. Try replacing X1. If that doesn’t help, we’re inclined to agree with you that IC1 is either faulty or has lost its programming. The only way to know for sure which is the case is to buy a PIC programmer and attempt to reprogram it with our HEX file. If that doesn’t work, you will need a new PIC chip. While it is not very common, we do occasionally hear of faulty microcontrollers. In one or two cases, the program appeared to have been erased or corrupted, despite it having been programmed and verified correctly. LC Meter provides incorrect readings for certain capacitor values I built your Wide-Range LC Meter as described in the June 2018 issue (siliconchip.com.au/Article/11099). Boy, do I love the easy functionality that combining an Arduino with a relatively simple bit of circuitry brings. But I have struck a problem with it. It works just fine with capacitors from 100pF to 100nF. From 200nF to 1µF it reads low, about one or two decades lower than the actual value. For example, 490nF of capacitance reads as 16nF (Fosc = 125,563Hz). From 2µF and above, it is just fine. The fact that it works fine below 200nF and above 2µF suggests to me that I’ve built it correctly. I had a look at waveforms at the Arduino D5 input (the output from the LM311 IC) and what I see is that as the capacitance value increases above 200nF, the leading and trailing edges of the waveform becomes increasingly ‘broken’, with additional low/high transitions. My guess is that the waveform from the top of the tuned circuit is passing too slowly through the linear region of the LM311 comparator input. The increasing number of spurious transitions I am seeing could therefore be due to noise on siliconchip.com.au the input. As the capacitor value gets smaller, the time in the linear region is smaller, and the comparator can’t switch its output within that time. Looking at the signal at CON3, as the capacitance increases, the amplitude of the sinewave becomes small, and there is a lot of high-frequency noise apparent. After doing some internet searching, it seems that this circuit configuration is well known for this problem and some people even refer to it failing at around 300nF. I guess your prototype works right through to at least 1µF, so maybe variations between samples of the LM311 IC can be significant. Your article makes a rather cryptic comment about trying to improve the oscillator without success. Do you have any suggestions for how to fix my unit? (I. P., Loganholme, Qld) • Our attempts to improve the oscillator mainly involved trying different component values; perhaps unsurprisingly, we found the values in the classic Neil Heckt circuit to be close to optimal and therefore decided to leave them as-is. You may be right that your problem is due to instability, as the optimal values appear to be right at the edge of stability. Australia’s electronics magazine We sourced our LM311 ICs from Jaycar, but there’s no guarantee that all the parts they stock are from the same batch or manufacturer. We chose a 2µF threshold because we found our oscillator to be stable to slightly above that value. The unit checks the approximate value before running the test, and if it’s above 2µF, it uses the RC method instead. This decision is made on line 114 of the code (from the current version on the website). You could try dropping this threshold to 200nF or lower (eg, change “2.0e-6” to “2.0e-7”). This would be the ‘quick and dirty’ method of getting your unit working, and would mean that the LC meter would use the RC method for values down to 200nF. That should work, but it may be slightly less accurate. If possible, you should try using a different LM311 IC; ideally, one from a well-known manufacturer like Texas Instruments. Other things you can try are using a different power supply (excessive noise from the power supply may be getting into the oscillator), changing the two tantalum capacitors to low-ESR types and checking all your soldering, as a high-resistance joint could affect the circuit’s operation. September 2019  125 Troubleshooting old motor speed controller I built your May 2009 10A Full Wave Motor Speed Controller (siliconchip. com.au/Article/1434) from a Jaycar kit, Cat KC5478. After building it, I tested with a drill, and it worked well. When I went to use it again a few weeks later, there was no speed control; the drill just ran at full speed. I later realised that this drill already had a variable speed trigger, and using such a drill with the speed controller is a no-no. I went through the instruction troubleshooting guide using a 12V supply, and found that all the test points measured 11.7V. There was no variation in voltage when turning variable resistor VR1. I also measured 11.7V on pin 7 of IC3 and the gate of Q1. I tested VR1 separately and found that the resistance from the wiper to each end varied correctly, between 0W and 5kW. I have no experience testing electronics, and don’t have a great understanding of how the circuit works. Any pointers greatly appreciated. (M. V., via email) • Firstly, you need to figure out why the VR1 wiper does not vary the voltage at TP1. That is probably the cause of the drill always running at full speed. There could be an open connection in the 8.2kW resistor that connects the bottom end of the potentiometer to 0V. Check the IC supply pins. Pins 1 & 11 of IC1, pin 1 of IC2 and pins 8 & 14 of IC4 should all read 12V. If you can find the cause of the lack of voltage variation from VR1, the averaged IGBT gate voltage (as read by a DMM set to measure DC volts) should then vary as VR1 is rotated. If it still doesn’t work then IGBT Q1 could be damaged. This can be checked by measuring the resistance between its collector and emitter. If you get a low ohms reading, then it is shorted and will need to be replaced. Questions about Majestic loudspeakers I’m currently building a pair of your Majestic loudspeakers, as described in the June & September 2014 issues (siliconchip.com.au/Series/275). In the June issue, there is a photo on page 31 which shows a view of the 110mm diameter circular vent hole. The vent appears to have some kind of insert inside it, which is not referenced in the text. What is it, and where can I get it? Also, is there any reason why I can’t add a bottom panel to the base of each speaker box so that I can attach castors below, to make the speakers easy to move? (R. C., Baulkham Hills, NSW) • Allan Linton-Smith replies: the black insert you refer to is the remains of a 110mm port which was originally available from Altronics, but is no longer stocked. We tried using a port initially but discovered that it made no difference to the sound, so we simply cut it off flush, as you can see in the photo. So don’t worry about the port, just cut the hole as specified and all will be well! Regarding adding baseboards to the speakers, it will slightly reduce the bass output because the floor becomes part of the overall cabinet, and by lifting the cabinet up off the floor, they will interact in a slightly different manner. I know this because I have been listening to the prototype Majestic speakers in my garage and they are propped up on a board, about 10cm above the floor (to protect the speakers from water damage). They definitely do not sound as good bass-wise as when they are indoors and sitting on a timber floor! But keep in mind that there are a lot of variables which affect the sound, such as your room dimensions, speaker position, room furnishings etc. So I can’t give any concrete guidelines, except to say: try it and see. The speakers are heavy indeed, so if you aren’t going to add wheels, study handles might be another option to make moving them easier. SC Building the Majestic loudspeakers with an active crossover I want to build a DIY audio system, and am considering building your Majestic loudspeakers (June & September 2014; siliconchip.com.au/ Series/275). But you’ve published two active crossover projects since then; the 3-way Active Crossover (September & October 2017; siliconchip. com.au/Series/318) and the DSP Active Crossover (May-July 2019; siliconchip.com.au/Series/335). So I want to ditch the passive crossover designed for the Majestics in favour of one of these active crossovers. But I don’t have the equipment to match the Majestic cabinet and drivers to the active crossover frequencies and slopes. I think this needs to be done with high-end speaker testing equipment and a keen ear! Is this possible? (B. T., via email) 126 Silicon Chip • We haven’t tested it, but the Majestics should perform well with an active crossover. Setting it up shouldn’t be too difficult, nor should you need any expensive test equipment. We suggest that you set it up with a Linkwitz-Riley response (aka ‘Butterworth Squared’) and set the crossover point close to 1.5kHz. That is the approximate crossover frequency for the original passive crossover, as shown in Fig.2 on pages 34 of the June 2014 issue. As mentioned in that article, the tweeter is 12dB more efficient than the woofer, so you need to adjust the active crossover and/or your amplifiers to allow for this. If you have a basic signal generator and a voltmeter that can measure over the audio spectrum (up to a few kilohertz), that’s quite easy to do. Australia’s electronics magazine Inject a 750Hz (or thereabouts) signal into the active crossover at a fixed level, measure the voltage across the woofer amplifier outputs and write that figure down. Then inject a 3kHz signal into the active crossover at the same level, monitor the voltage across the tweeter amplifier and adjust the tweeter amplifier level to get a reading that is one quarter that for the woofer (-12dB = ¼V). With the DSP Active Crossover, it should also be possible to configure it for a high-frequency boost above 10kHz, as we did with the passive crossover, to compensate for tweeter high-frequency roll-off. You may need to adjust the relative amplifier levels slightly by ear to get the best result, but the above procedure should get you pretty close. siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP FOR SALE KIT ASSEMBLY & REPAIR tronixlabs.com.au – Australia’s best value for supported hobbyist electronics from your favour ite brands – along with kits, components and much more – with flat-rate $8 delivery Australia-wide. KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith: 0409 662 794 keith.rippon<at>gmail.com LEDs, BRAND NAME and generic LEDs. Heatsinks, fans, LED drivers, power supplies, LED ribbon, kits, components, hardware, EL wire. www.ledsales.com.au DAVE THOMPSON (the Serviceman from S ILICON C HIP) is available to help you with kit assembly, project troubleshooting, general electronics and custom design work. No job too small. Based in Christchurch, NZ but service available Australia/NZ wide. Email dave<at>davethompson.co.nz PCB PRODUCTION PCB MANUFACTURE: single to multi­ layer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au NEED A NEW PCB DESIGNED? Or need to update an old board? We do PCB layouts from circuits, drawings, photocopies or sample boards. Contact Steve at sgobrien8<at>gmail.com or phone 0401 157 285. Get a new PCB and keep production going! VINTAGE RADIO REPAIRS: electrical mechanical fitter with 36 years ex­ perience and extensive knowledge of valve and transistor radios. Professional and reliable repairs. All workmanship guaranteed. $17 inspection fee plus charges for parts and labour as required. Labour fees $38 p/h. Pensioner discounts available on application. Contact Alan, VK2FALW on 0425 122 415 or email bigalradioshack<at>gmail. com WANTED LOOKING FOR: a) Set of Dick Smith Electronics catalogues from 1975-1982. Must be in pristine condition. Will pay $100 for the set (inc. postage), only one set needed. b) Copy of a book once sold by Jaycar entitled “High Power Loud Speaker Enclosure Design & construction”’; catalogue number BC1166. Will pay $50 (inc. postage) to the first with a pristine copy, ie, little use; slight dog ears OK. Contact Melanie (on behalf of inquirer on 02 8832 3100) MISCELLANEOUS ASSORTED BOOKS FOR $5 EACH Selling assorted books on electronics and other related subjects like audio, video, programming etc. The books are relatively old in most cases and vary in condition. All books can be viewed at: https://imgur.com/a/gnSWoII Some of the books may not be for sale, but the vast majority are available. Bulk discount available; post (cost varies) or pickup. Silicon Chip silicon<at>siliconchip.com.au ADVERTISING IN MARKET CENTRE Classified Ad Rates: $32.00 for up to 20 words (punctuation not charged) plus $1.20 for each additional word. Display ads in Market Centre (minimum 2cm deep, maximum 10cm deep): $82.50 per column centimetre per insertion. All prices include GST. Closing date: 5 weeks prior to month of sale. To book, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or phone Glyn (02) 9939 3295 or 0431 792 293. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. siliconchip.com.au Australia’s electronics magazine September 2019  127 Coming up in Silicon Chip Universal 6-24V Battery Charge Controller This Battery Charge Controller turns a ‘dumb’ battery charger into a smart charger, suitable for use with various 6V, 12V or 24V batteries, including leadacid, gel-cell, Li-ion and LiFePO4 (lithium-ion phosphate). It has three preset charging profiles and three adjustable profiles with one to three-stage charging. Advertising Index AEE Electronex........................... 5 Altronics...............................82-85 Ampec Technologies................. 13 50V 8A Linear Bench Supply Blamey Saunders hears.............. 9 Coming soon, this fully analog design which delivers plenty of current with low noise. We will also be presenting a low-cost digital multi-parameter panel meter that can be added to it, to monitor its various operating parameters. Control Devices......................... 51 How Satellite Navigation (GNSS) Works Digi-Key Electronics.................... 3 Dr David Maddison explains how satellite navigation systems work, including GPS (USA), GLONASS (Russia), Galileo (EU), BeiDou (China), NavIC (India) and QZSS (Japan). Dave Thompson...................... 127 Electrolube Australia................. 48 ELF Electronics......................... 15 New Arduino Nanos Emona..................................... IBC We take a look at the new Nano Every (based on the ATmega4809) and Nano 33 IoT (ATSAMD21 Cortex-M0+ with WiFi & Bluetooth LE) modules. Hare & Forbes....................... OBC Three I/O Expander modules Jaycar............................ IFC,61-68 Running out of microcontroller pins? These low-cost modules make it a breeze to add more functions to your existing micro. In some cases, they won’t take up any more pins on your existing micro and can add dozens more, including pins with PWM capability. Keith Rippon Kit Assembly...... 127 Note: these features are planned or are in preparation and should appear within the next few issues of Silicon Chip. The October 2019 issue is due on sale in newsagents by Thursday, September 26th. Expect postal delivery of subscription copies in Australia between September 25th and October 11th. Notes & Errata Fluidics and Microfluidics, August 2019: on page 17, the images for Fig.8 and Fig.9 are swapped. Dual 12V Battery Isolator, July 2019: if you use the specified LP2950 regulator, it’s necessary to add a 4.7kW resistor between 5V and GND for the unit to work properly. It will also work with a 78L05 regulator in place of the LP2950, although that will increase the quiescent current by around 3mA, compared to adding the resistor which only increases it by around 1mA. Future PCBs supplied will have a location to fit this extra resistor. AM/FM/CW HF/VHF RF Signal Generator, June & July 2019: the second article describes the core for transformer T1 as being 7mm long in some places and 14mm long in others. It should be 7mm, although a 14mm core will work; it’s just harder to fit. Also, if you use the Jaycar Cat QP5516 LCD with DIL pin header, you need to swap the pin 1 & 2 connections from the PCB (by replacing those two pins with short lengths of wire) as its pinout is slightly different from the Altronics Cat Z7018 LCD. This is not necessary for the Jaycar Cat QP5521 LCD which has a SIL pin header. Finally, some constructors have found that the 1kW resistor next to Q4 on the PCB (connected to its collector) needs to be increased in value (eg, to 10kW) so that the unit can be switched off by pressing S3. Bridge-mode Audio Amplifier Adaptor, May 2019: in Fig.30 on p70, the negative terminal of CON4 is incorrectly drawn as being connected to both pins 1 & 2 of CON5. The positive terminal of CON4 only connects to pin 1 of CON5, and the negative terminal only connects to pin 2. 128 Silicon Chip Australia’s electronics magazine LD Electronics......................... 127 LEACH PCB Assembly............. 47 LED Autolamps........................... 6 LEDsales................................. 127 Mastercut Technologies............. 12 Microchip Technology........... 11,57 Mouser Electronics................. 7,99 Ocean Controls........................... 8 On-Track Technology............... 113 PCB Designs........................... 127 Rohde & Schwarz...................... 49 Silicon Chip Shop...........120-121 The Loudspeaker Kit.com....... 119 Triple Point Calibrations............. 46 Tronixlabs................................ 127 Vintage Radio Repairs............ 127 WAGO Pty Ltd........................... 45 Wagner Electronics................... 10 Wiltronics Research.................... 4 siliconchip.com.au “Rigol Offer Australia’s Best Value Test Instruments” Oscilloscopes FREE OPTIONS Bundle! 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