Fullscreen HTML5Med Res (??MB)HTML4

DECEMBER 2021 ISSN 1030-2662 12 The VERY BEST DIY Projects! 9 771030 266001 $ 50* NZ $1290 SMD 11 INC GST INC GST Trainer and how to solder surface-mount parts The small but powerful Hummingbird Amplifier Hands-on with the Raspberry Pi Pico siliconchip.com.au December 2021  1 The smallest Raspberry Pi yet! Australia’s electronics magazine Build your own Christmas Lights Controller Re-purpose or jazz up your Christmas lights with this Arduinobased Christmas lights controller project. It uses the traditional UNO prototyping board, and allows you to customise it with your own sensors, etc. Alternatively, you could even use the UNO with Wi-Fi (XC4411 $39.95 sold separately) to make it IoT controlled. SKILL LEVEL: INTERMEDIATE CLUB OFFER BUNDLE DEAL For step-by-step instructions & materials scan the QR code. 3995 $ www.jaycar.com.au/christmas-light-controller See other projects at SAVE 40% www.jaycar.com.au/arduino CLUB OFFER BUNDLE DEAL 14 $ 95 SAVE 30% KIT VALUED AT $22.80 KIT VALUED AT $69.77 LED Christmas Tree 100 gift card Arduino® Compatible Prototyping Board Shield XC4482 Got a great project or kit idea? If we produce or publish your electronics, Arduino or Pi project, we’ll give you a complimentary $100 gift card. Upload your idea at projects.jaycar.com 85¢ + 180Ω 0.5W Metal Film Resistors - Pk8 RR0554 + ONLY 40¢ EA Light Emitting Diodes (LEDs) ZD0150 5 x 5mm Red 10 x 5mm Green ZD0170 Looking for your next build? Silicon Chip projects: jaycar.com.au/c/silicon-chip-kits Kit back catalogue: jaycar.com.au/kitbackcatalogue 1800 022 888 www.jaycar.com.au Awesome projects by On 24ilicon November to 2 Sale S Chip 26 December, 2021 ONLY 95 Add a bit of Christmas spirit to your workbench and learn how multiple LEDs can be controlled from microcontroller pins. Arduino based, the LEDs can be customised to your liking. Requires Arduino® UNO Board sold separately. For step-by-step instructions visit: www.jaycar.com.au/led-christmas-tree $ ONLY 15 $ Australia’s electronics magazine Shop online and enjoy 1 hour click & collect or free delivery on orders over $99* siliconchip.com.au Exclusions apply - see website for full T&Cs. * Contents Vol.34, No.12 December 2021 SILICON CHIP www.siliconchip.com.au Features & Reviews 12 Big Brother is Tracking You! – Part 2 Following on from last month, this article goes into detail about how governments monitor their citizens, covering what data is collected and how, including metadata and mobile phone IMSI catchers – by Dr David Maddison 30 SMD Soldering – tips and tricks There’s a lot of jargon surrounding SMDs and the techniques used when working with them. We cover common component sizes, tools, cleaning, the type of tips and solder to use, along with some of the more advanced soldering techniques such as drag and wave soldering – by Tim Blythman 43 El Cheapo Modules: 35MHz-4.4GHz Signal Generator Geekcreit’s signal generator is a self-contained module based on an Analog Devices ADF4351; all you need is a 5V DC power supply – by Jim Rowe Requiring just throughhole parts, the Hummingbird Amplifier is easy-to-build, and powerful for its size. Multiple can also be combined to form more complex designs – Page 18 48 Review: Raspberry Pi Pico The Raspberry Pi Pico costs around $5 and yet is a powerful microcontroller board with great features – by Tim Blythman Constructional Projects 18 Hummingbird Audio Amplifier This mini amplifier delivers up to 60W into 8W or 100W into 4W and it can be easily made into a multi-channel amplifier system by mounting several onto a single heatsink together – by Phil Prosser 38 SMD Trainer Board If you’re interested in learning how to solder SMD components, or just want to try your hand at working with components as small as a grain of sand, then give it a go with our SMD Trainer board. It’s a great way to practice soldering a variety of SMD parts and seeing it flash to indicate everything’s fine – by Tim Blythman Many projects these days use at least one SMD. If you aren’t confident in soldering SMDs or want to polish up your skills, this article is for you – Page 30 61 Digital Lighting Controller Translator This Translator allows our latest Digital Lighting Controllers to communicate with any of the slave units. This means that slave units designs from 2010-11 can be controlled with our Lighting Controller Master from 2020 – by Tim Blythman 85 USB Cable Tester – Part 2 Ideal for troubleshooting and going through piles of cables, we finish construction of the USB Cable Tester and show you how to use it – by Tim Blythman Your Favourite Columns 68 Serviceman’s Log A mixed bag of odds, sods, ends and bobs – by Dave Thompson 76 Circuit Notebook From M3216/1206 to M0603/0201 sized resistors and LEDs, plus a USB connector, SSOP-16 IC and more. This SMD Trainer has many different components for you to practice soldering – Page 38 (1) Micromite BackPack Planetarium (2) Contactless temperature sensor (3) Parallel/series cell switcher (4) Two pushbuttons on an input-only pin 94 Vintage Television Restoring a Sony 5-303E Micro-TV – by Dr Hugo Holden Everything Else 2 Editorial Viewpoint 4 Mailbag – Your Feedback 74 Product Showcase siliconchip.com.au 105 Subscriptions & Shop 108 Ask Silicon Chip 111 Market Centre 112 Advertising Index Australia’s electronics magazine 112 Notes & Errata The Raspberry Pi Pico is a new and interesting microcontroller board. It costs just a bit over $5 and measures 51 x 21mm, making it compact and well-suited for December 2021  1 breadboard use – Page 48 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. Nicolas Hannekum – Dip.Elec.Tech. Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Allan Linton-Smith Dave Thompson David Maddison – B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Geoff Graham Associate Professor Graham Parslow Dr Hugo Holden – B.H.B, MB.ChB., FRANZCO Ian Batty Phil Prosser – B.Sc., B.E.(Elec.) 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 (Australia only): 6 issues (6 months): $65 12 issues (1 year): $120 24 issues (2 years): $230 Online subscription (Worldwide) 6 issues (6 months): $50 12 issues (1 year): $95 For overseas rates, see our website or email silicon<at>siliconchip.com.au Recommended & maximum price only. 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. Making kits is not easy! You might have noticed the announcement last month that we are selling an almost complete kit for the USB Cable Tester project. As we were building the prototypes we realised that, due to ongoing shortages, there was no guarantee that the parts would be available by the time the project was published. And what would be the point in publishing a project article if nobody could build the thing? Of course, there are other reasons to offer kits. We realise that it’s much easier for readers to build most of our designs if they can buy all the parts as a set, rather than running around gathering them from various sources. It can also be cheaper to buy a kit, mainly because you don’t have to pay delivery fees to multiple vendors. There are two primary reasons we haven’t done this in the past. One is that Jaycar and Altronics have tended to produce kits for our projects (and still do, thankfully; see below), and we didn’t want to ‘step on their toes’. Another is the perception that it would be a lot of work to produce kits, distracting us from working on the magazine. Our experience now shows us that concern was not misplaced. It might seem like a simple job to make a kit; just order some parts, throw them in a bag, and then send that to the customer, right? Well, it turns out it isn’t quite that easy. Problem number one is estimating the demand. It takes time to find all the vendors, order the parts, gather those orders, and then make the kits, so you need to do it well before the article is published. But how do you know how many parts to order before you’ve had a chance to gauge reader interest? Order too few sets, and you run the risk of delaying getting kits to customers (or, under the current circumstances, possibly not being able to supply them at all!). Ordering too many not only means a large cash outlay upfront, but it could even result in the whole exercise being a net loss, with a bunch of unsold kits sitting around taking up space. Once you’ve figured that out, it takes a surprising amount of time and labour to actually order the parts, track all the incoming shipments and then put it all together in preparation for making the kits. The kit-making then takes a deceptively large amount of time and effort. Some parts are not easily separated. Some need re-packing. Some need programming. Some need to be cut or broken apart into smaller sections. Often, they need to be separated into several bags or other containers to be later combined to make the final kits. Some parts need extra protection to survive delivery (anti-static bags, foam, tape, bubble wrap etc). You also need to be meticulous to ensure you don’t leave anything out of a kit and put in the correct number of each component. The time spent doing all these things adds up, and it ends up consuming way more hours than you might guess when making dozens or even hundreds of kits. I’m delighted that our SMD Test Tweezer and USB Cable Tester kits have been so popular (partly because it shows that people enjoyed the articles), but it will be a relief once we get all the kits to our customers! Altronics kit for projects in this magazine Printing and Distribution: Finally, I am pleased to announce that Altronics will be producing kits for three projects this month: the Hummingbird amplifier (starting on p18), SMD Trainer (p38) and Digital Lighting Controller Translator (p61). See the respective parts lists for the relevant code that you can search for on their website. 24-26 Lilian Fowler Pl, Marrickville 2204 Cover background image source: www.freepik.com/free-vector/realistic-motion-neon-lights-background_15292690.htm ISSN 1030-2662 2 Editorial Viewpoint Silicon Chip by Nicholas Vinen Australia’s electronics magazine siliconchip.com.au siliconchip.com.au Australia’s electronics magazine December 2021  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 had the right to edit, reproduce in electronic form, and communicate these letters. This also applies to submissions to “Ask Silicon Chip”, “Circuit Notebook” and “Serviceman’s Log”. Important information about the Tele-com (OzPLAR) In the Tele-com article on page 38 of the October issue, one of the alternative transformers for the ringer section in the parts list is shown as Triad FS24-100-C2 (Mouser Cat 553-FS24100-C2). This should instead be Triad FS24-100 (Mouser Cat 553-FS24-100). Note that the Altronics M7024A is a good performer, and about the same price as the Triad FS24-100. The FS24-100-C2 version (while cheaper) is designed to be short circuit proof, and as a result, it just doesn’t perform well in the ringer circuit. I purchased quite a few and was disappointed to discover this. Another recommendation that isn’t covered in the article is the type of self-tapping screw used to mount the board in the Pac-Tec LH96-200 case. I initially used some 8mm-long 4G self tappers and found that one of the mounting stand-offs in the case split down the side. The PT (Plas-tite) screws WN1411KB30X6Z available from PSM Fasteners in Marrickville, NSW can be used to avoid this happening. Editor’s note: we usually find 4G/3mm screws to be fine for this sort of job, but perhaps 8mm is a bit long; 6mm screws are less likely to split the posts. Note that both feed bridge designs were tested using a power supply similar to those in the parts list, and we could not notice any audible switching artifacts in the telephones. However, some constructors may not use the recommended PSU and instead elect to use a small plugpack such as the Altronics M8968B (superseded by 4 Silicon Chip M8968C) because they are considerably cheaper. Testing with the M8968B after the article went to press showed that when the LB1011AB feed bridge was used, switching artefacts were audible in the telephones as an annoying ‘digital squeal’. It is not noticeable when the M1000 inductor feed bridge is used with the M8968B. Fitting the M8968B with an 820μH inline inductor using adhesive heatshrink and decoupling pin 8 of both LB1011ABs with 4.7μF 50V capacitors effectively eliminated the noise. Still, the likelihood of constructors opting for the LB1011AB feed bridge is minimal, although we can supply them if needed. The 820μH inductor tested was Mouser Cat 815-AIAP03821K. I used 6mm adhesive heatshrink (Altronics W0994A) to increase the diameter of the cable on the M8968B and sheathed the inductor with 19mm adhesive heatshrink (shown below; Altronics W0997A). I haven’t checked the switching frequency of the Altronics M8968B, but I suspect it is around 500kHz. I also tested a plug pack that operated at 50kHz, and the modified inductor/ capacitor filter arrangement effectively suppressed the noise from that as well. Ross Herbert, Carine, WA. Silicon Chip magazines to give away I have many Silicon Chip magazines that I wish to give away. If you are interested, please e-mail silicon<at> siliconchip.com.au and they will pass your message on to me. John Maarssen, Thornlie, WA. Australia’s electronics magazine SMD Test Tweezers – more than just something to build This is just a note to let you know how much I enjoyed the October article by Tim Blythman on the SMD Test Tweezers. I went right ahead and purchased the kit but never built it! My interest started because I was curious about how to use the OLED display, how the sleep mode worked and anything else I could learn from it. It is great that you make the source code available, so I immediately downloaded the C source code from your website. I’m by no means a ‘crack’ C programmer. Still, on opening the code in MPLABX, it just looked very neat and concise with its separate includes for the I2C communications, the OLED operation and convenient utility routines such as getDigit for displaying on the OLED. I mapped the font.h file onto a spreadsheet with “x”s to see how the fonts were made. It was a real learning experience. For example, I discovered the term “include guard” when exploring the #defines. I always had a vague idea what that was about, but there it is, nice and simple. It inspires one to try to write neat code. I’ve decided to get familiar with the PIC16F1459, so as an exercise, I set the circuit up on a breadboard, using different pins (because the processor is different). I created a new MPLAB X project with your code and began porting it across. All this meant getting familiar with MPLAB X again, fiddling around with the PICkit programmer and using different pins for wake up on interrupt. In the end, I now have a nice little siliconchip.com.au test jig (which behaves as a pair of test tweezers) for practising with I2C driven OLED displays and a whole lot of new ideas as to how to format the code. The reason I’ve written is to thank you for your efforts and to let you know a different angle from which some of your readers might derive enjoyment from such projects. Dave McIntosh, Eastwood, NSW. Backwards compatibility nightmares My reading list is far and wide, and I always read (or at least flip through) your magazine with interest because I never know what I will find. April’s edition was no exception, and I wanted to add to your editorial comments (“Adobe making our lives difficult”), which are not exclusive to Adobe. I published some books on lighting design, for which a few of the fonts have since been ‘updated’. This means that I need to change the whole contents because the new fonts are not only ghastly and inappropriate, but they completely scramble all of my work, including paragraph endings, tables and the like. To overcome this problem without re-doing the layouts, I check with the printers to ensure that the fonts I’ve typed are still in their system. That is the best I can do under the circumstances, though I now have three publications requiring the same method for printing. But it doesn’t stop there! When I was forced to upgrade to a new computer and Windows 10, I was assured that every piece of technology would work on the new system. However, my brilliant Epson 1260 scanner, which also does 35mm colour slides and negatives, would not work. After wasting so much time, I contacted Epson directly only to be told that the scanner was too old and I needed to purchase another item which is superior (probably because it was also a printer – whoopty-doo). This is what it’s all about – getting us to upgrade all of our equipment whenever a newer model is produced. Thank goodness the medical professional doesn’t value our lives in the same manner! Then a few months ago, I thought I’d watch a quick DVD on Windows 10, only to discover that I now need to purchase and download an app 6 Silicon Chip that will allow my DVD player to run. This is absolute nonsense in its highest form. The new regime has allowed third parties to piggyback and make more money by stealth, not only in the computer industry but with most bookings or purchases done online. As a result of all this, I have had to go back to using Windows Vista on my laptop so that I can use my preferred software. But I have to keep it offline to ensure that there are no ‘updates’ that break its operation. Some of us try desperately to uncomplicate our lives. I look forward to your next edition of Silicon Chip. Karen Wardell, Nelson, New Zealand. Comment: perhaps the most frustrating aspect of this culture of providing updates that break backwards compatibility is how little these companies, to whom we pay a considerable amount of money to use their software, seem to value our time or effort. They are quite happy to cause us hundreds of hours of work and frustration, then act as though they are doing us a favour. More feedback and a suggestion A quick note to let you know I really enjoyed the October issue; it is packed with many interesting projects and reviews! I was also wondering if you’d consider publishing an updated electronic load circuit. This is a very handy device on the bench, and the last Silicon Chip design is from 2006. Olivier Aubertin, Singapore. Comment: we have a contributor working on an electronic load design, and it sounds like it will be finished soon. Getting competitive about vintage gear I expect another older reader will top this, but I can beat Greig Sheridan’s venerable EA power supply (mentioned in his letter you published in the October issue) by some decades. That magazine’s predecessor, Radio, Television & Hobbies, published an FM tuner circuit in January 1957, presented by its avuncular editor, John Moyle. The one I built was in almost everyday use until the advent of stereo FM in the mid-seventies and supplied my LP disc cutter with high-quality ABC orchestral concerts. It is still working perfectly (mono only, of course) with its original four 6AM6 valves. Today, Australia’s electronics magazine it sits under my bench, and I listen to it now and again simply for the sentimental satisfaction of keeping it alive. Brian Wallace, Dora Creek, NSW. Windows updates and DMM AC calibration In your July editorial, I noticed that you pinged Microsoft for their dodgy fix that didn’t fix. Shock horror. You’re surely not suggesting that Microsoft sells software of dubious quality. Let’s not forget that one of the first, if not the first, vulnerabilities exposed in Windows XP was inherited from Windows NT, and Microsoft knew about it for years but did nothing to fix it. I think you need to keep in mind that the primary aim of almost every company is to make profits, and manufacturing something or supplying goods or services is just the process they use to achieve that end. Providing superior products, services etc comes at an extra cost which has to be passed onto customers or taken out of profits. Some companies have successfully managed to provide quality as well as make a profit, although many more have delivered quality and gone bust. So to stay up with the competition, flashy new thingamabobs are often the more cost-effective route to staying in business. Henry Ford is reputed to have said that “There is one rule for the industrialist and that is: Make the best quality goods possible at the lowest cost possible, paying the highest wages possible.” Modern manufacturers have pretty much ditched the last part and are concentrating on the second at the expense of the first. It is a cut-throat game. Having said all that, I must add that my observation is that most goods I use these days are of higher quality and provide greater utility than they ever have in the past 60 years, and they are relatively cheap. Smartphones and computer systems would be the most glaring exceptions to that. Fortunately, although life could be better, it could also be much worse. I’ll finish this diatribe with an observation from the late, great Douglas Adams: “The idea that Bill Gates has appeared like a knight in shining armour to lead all customers out of a mire of technological chaos neatly ignores the fact that it was he … [who] led them into it in the first place ...” siliconchip.com.au Can you deliver reallife technology solutions? Is the answer automated smart grids that connect industry and households to renewable energy? Could you engineer robotic systems that improve safety and increase efficiency in manufacturing and farms? Work alongside USQ’s world-class lecturers and help solve current industry problems with a USQ engineering degree. Study 100% online, on campus or a mix of both. #1 uni in Australia for graduate starting salary in engineering.^ Experience more opportunities and personalised support with our small class sizes. Join this in-demand industry and study electrical, mechatronic, computer systems engineering and more. USQ Engineering ^ Good Universities Guide, 2022 CRICOS: QLD 00244B, NSW 02225M | TEQSA: PRV12081 Helping to put you in Control Spectrally Flat Class C Pyranometer DeltaOHM PPYRA03AC – Spectrally Flat Class C Pyranometers according to ISO 9060:2018. Complete with levelling device and calibration report. SKU: OHM-001 Price: $1545.50 ea UC100 USB Motion Controller Directly replaces the traditional Parallel port with modern USB. Can control up to 6-axis with Mach3, Mach4 or UCCNC software. Up to 100kHz step frequency operation, Fast communication with data buffer for robust and stabile operation. SKU: CND-001 Price: $198.00 ea M18 Shielded Inductive Proximity Sensor NPN, NO+NC IPSI/L-18NOC5B Shielded (flush) M18, 4-wire NPN-style output with NO+NC contact type. It has a sensing distance of ~5 mm. Screw on connector. Choose 2m cable with straight or 90 degree 4 wire M12 connector. SKU: IBS-0280 Price: $30.25 ea Programmable Range Pressure Sensor Novus Automation’s NP620 Programmable Range pressure sensor with input range of 0 to 10 Bar. 2-wire 4 to 20 mA output, 0.25% accuracy and 1/2” BSPP process connection. SKU: NOS-206 Price: $259.60 ea 604 Differential Pressure Switch Huba 604 is used as a DP flow switch in ventilation ducts for the control of filters and fans, and in control systems for the control of dampers. Pressure range 0.2-3mbar option 1-10, 0.5-5, 10-50. SKU: NOS-2600 Price: $307.95 ea Thermostat Controller with NTC Sensor and Buzzer Panel mount thermostat with included NTC sensor on 2 m lead. Configurable for a huge range of heating and cooling applications. Fitted with Buzzer for alarm. 100 to 240 VAC powered. SKU: CET-0012 Price: $121.00 ea 2.0 N·m NEMA 23 Integrated Stepper Motor iST-2320 2.0 N·m NEMA 23 stepper motor with integrated driver. Standard pulse and direction (or CW/CCW) input. Advanced antiresonance DSP driver. Comments on component shortages SKU: SMC-126 Price: $241.95 ea For Wholesale prices Contact Ocean Controls Ph: (03) 9708 2390 oceancontrols.com.au Prices are subjected to change without notice. 8 Silicon Chip Also, I thought about R.M.’s problem of measuring AC for calibration purposes (Ask Silicon Chip, July 2021, page 110). Most DMMs do not have very high accuracy on the AC ranges, usually much poorer than the specified DC accuracy. For example, Keysight U123x meters have specified DC accuracy of 0.5%, AC accuracy of 1% for the low voltage ranges, and frequency accuracy of 0.1%. I used to own one, and I thought it was a great general-purpose instrument. The corresponding figures for the U1282A are 0.025%, 0.3% and 0.005%. I own one now but rarely use it because it’s expensive, and I don’t want to damage it. 1% is a pretty typical accuracy for the AC ranges on DMMs. You recommend that R. M. use a “low-distortion sinewave oscillator”, but consider how much distortion contributes to the RMS value of a (nominal) sinewave. Because you have to use the root-of-sum-of-squares method to add distortion and fundamental the distortion has to exceed 14% before the RMS value increases by 1%. A 1V RMS sinewave with 1% distortion has an RMS value of 1.00005V RMS, which is well within the accuracy of even five- or six-digit DMMs. I realise that “low-distortion” is a relative term, but even a cheap function generator should deliver acceptable performance. Besides, if you are using the LTC1966 as a reference, it should be irrelevant what the waveform is so long as it is within the meter’s crest factor capabilities. The exercise is complicated by the LTC1966 working over a fairly small range, up to 500mV max, so it cannot be used reliably to calibrate higher voltage ranges without also calibrating the gain circuit. Also, strict attention must be paid to the effects of loading, both resistive and capacitive. If the multimeter is not a ‘True RMS’ meter, the need is less. Phil Denniss, Darlington, NSW. Nicholas comments: You are right; a pretty basic sinewave generator should be fine for calibrating most DMMs on AC voltage ranges. The main requirement is that sinewave amplitude must be more precisely known than the DMM’s measurement tolerance. Also, some of the blame for how buggy computer software has become must lie with consumers. The reason software companies prioritise adding bells and whistles over fixing bugs or improving performance is that they’ve figured out that is why people pay for their products. Consider that Microsoft and Apple essentially form a duopoly, and by refusing to license macOS to be run on hardware they do not sell, Apple allows Microsoft to act as a monopoly. Monopolies rarely lead to good outcomes for consumers. Linux is making inroads into the desktop market, but only slowly. Concerning your October Editorial Viewpoint, I am not surprised that components are also in short supply. This suggests that the situation will be quite bad for Silicon Chip and hobbyists because we are at the bottom of the pecking order. The inability of hobbyists to play with electronics simply does not rate against manufacturers who need to keep their production operational. Australia’s electronics magazine siliconchip.com.au Design Contest Win $500+ Dick Smith challenges you Win $500 by designing a noughts-and-crosses machine that can beat 14-year old me! Dick Smith has described in his new autobiography how one of the turning points in his life, at age 14, was succesfully building a ‘noughts-and-crosses machine’ (also known as tic-tac-toe) that could play the game as well as anyone. Keep in mind that this was in 1958, when nobody had computers; it was a purely electromechanical device. Email Design to Enter Design your own noughts-andcrosses circuit and send your submission to compo<at>siliconchip. com.au including: a) Your name and address b) Phone number or email address (ideally both) c) A circuit or wiring diagram which clearly shows how the device works d) The display can be anything as long as it’s understandable e) Evidence that your device can always play a perfect game (it never loses) f) A video and/or supply images and text describing it g) Entries requiring software must include source code The deadline for submissions is the 31st of January 2022. ➠ ➠ Win $500 + Signed Copy of Dick Smith's Autobiography ➠ Four winners to be decided, one each for the following categories: ➊ The simplest noughts-andcrosses playing machine most ingenious noughts➋ The and-crosses playing machine youngest constructor to ➌ The build a working noughts-and- DICK SMITH crosses playing machine most clever noughts-and➍ The crosses playing machine not using any kind of integrated processor The entry we judge overall to be the best will also be featured in our Circuit Notebook column and receive an additional $200. ‘Businessman, adventurer, philanthropist…Di ck Smith is a true Australian legend.’ JOE CITIZEN Conditions of entry Dick Smith writes 1) You must be a resident of Australia or New Zealand 2) One entry per family (Silicon Chip staff and their families are not eligible) 3) Submissions will be confirmed within 7 days. If you do not receive a confirmation of your submission, contact us to verify that we have received it 4) Chance plays no part in determining the winner 5) The judges’ decision is final 6) The winners will be decided by the 3rd of February 2022 and will be notified immediately By 1958 I’d advanced from building crystal radio sets to designing and building what I called a noughts and crosses machine. It really was an early computer. I used second-hand parts from a telephone exchange to build it. It would play noughts and crosses against anyone and no one could beat it. This was a great boost to me, because while I was no good at rote learning and theory, I was fine at practical things. The fact that my mind was capable of working out how to build this complex machine gave me confidence as I left school. Now I just had to find a job. Because this was such a turning point in his life and he’s so enthusiastic about youngsters learning electronics, he’s putting up $2000 of his own money to award to people who can come up with a modern version of his noughts-and-crosses machine. Silicon Chip will judge the entries. Winners will be announced in the March 2022 issue of Silicon Chip magazine and will also be contacted directly for payment information. siliconchip.com.au Australia’s electronics magazine December 2021  9 POWER SUPPLIES PTY LTD ELECTRONICS SPECIALISTS TO DEFENCE AVIATION MINING MEDICAL RAIL INDUSTRIAL Our Core Ser vices: Electronic DLM Workshop Repair NATA ISO17025 Calibration 37 Years Repair Specialisation Power Supply Repair to 50KVA Convenient Local Support SWITCHMODE POWER SUPPLIES Pty Ltd ABN 54 003 958 030 Unit 1 /37 Leighton Place Hornsby NSW 2077 (PO Box 606 Hornsby NSW 1630) Tel: 02 9476 0300 Email: service<at>switchmode.com.au Website: www.switchmode.com.au 10 Silicon Chip But hobbyists have one advantage; we can use recovered components, whereas manufacturers cannot afford the risk. For many years, I bought old equipment and PCBs to get expensive and rare components, and in doing so, I collected a lot of common parts. The result is that the shortage is not a hindrance to my experimentation. I realise that I am in a unique position, but there will still be old equipment with components that can be retrieved. One just needs a good hot air gun to make for easy removal. If you don’t already know, Wiltronics are still advertising surplus components. They are: BAS16 SOT-23, BC848C SOT-23, BC849C SOT-23, all in 3K reels <at> $30 per reel; TIP32B TO-220 as 500 pack <at> 73¢ each; 1SMB5941 47V diode 1.5W in 2K reel <at> $40; and 16V 5W Zener diode in pack of 1000 for $50. You can find these online at: www.wiltronics.com.au/ product-category/semiconductors-surplus/ The Dick Smith noughts & crosses competition intrigues me. I have no intention of entering it, but it is interesting that noughts & crosses is being revisited when it has been researched to death. The creation of an unbeatable machine is a trivial exercise. I will be very interested to see the winning entries. Regarding Mr Smith himself, I am impressed that he created an unbeatable machine at age 14, especially back in 1958. He was very fortunate to have access to telephone exchange parts as such things were almost impossible to obtain in the early 1960s, when I was his age. As I age (now 70) and suffer more and more from knotted neurons, I have become interested in technical people who have achieved something remarkable. Their stories are far more interesting than those from other areas of endeavour. The microprocessor used in the USB Cable Tester project of the October Silicon Chip edition is a new one to me, and I was curious to look at its specs. Since the COVID-19 pandemic has caused a shortage of microcontrollers, it has occurred to me that Microchip and other manufacturers may use the pandemic to rationalise their products. In particular, older ICs that use more silicon real estate than current products would undoubtedly be targets for phasing out. Since Microchip has a vast range of microcontrollers, I would expect them to take advantage of the situation. The PIC16F18877 looks like a drop-in replacement for many earlier microcontrollers, including some very popular ones that have been around for some time and are in short supply. Microchip has been very good at maintaining common pinouts on many of their microcontrollers, which is to their credit. However, the move to the ‘swiss army’ microcontroller does leave a bit to be desired because that increased complexity also leads to microcontrollers which are much harder to understand. George Ramsay, Holland Park, Qld. Comments: we reckon most people who’d be interested in entering the competition would already know how to win the game. The real challenge is coming up with a clever circuit that uses minimal components, especially if no microcontroller is involved. Australia’s electronics magazine siliconchip.com.au By the way, while the situation has stabilised somewhat, we can’t see the shortages going away until late 2022 at the earliest, and more likely 2023-2024. As far as we are aware, Microchip has never phased out a product, and we don’t think they will start any time soon. However, their older products become more expensive over time, making switching to newer devices attractive. They generally perform better and have more features at a lower price, so it makes a lot of sense to migrate code where possible. We are sure you are right about other manufacturers taking this opportunity to cull their ranges, though. Yes, Microchip does a great job of maintaining pin compatibility. For example, the PIC16F1887x family looks like a drop-in replacement for the venerable PIC16F877. We don’t think the new micros having more features is a problem. You don’t have to use all the features; many of them do nothing unless enabled, but it’s nice to have them present in case you need them. The processor cores are still pretty easy to understand and work with, although Microchip’s stablemate AVR processors are significantly easier to understand at a low level than the PIC series. A familiar tale of woe I read with particular interest your column in the October 2021 issue with respect to the global silicon chip shortage. Your Mosfet lead time quote is the worst one I have heard so far (2.5 years!), but for all the other MCUs I use at RICTECH, the lead-time is usually quoted as November 2022 at the earliest, so at least a full year of waiting at this stage. I sell the Colour Maximite 2 units on my website, and I have one left and no chips to get any more made for at least a full year, probably longer at the rate things are going. I will continue to offer it once I can get the chips again, but who will remember or even want one in a year? I was also interested in your Tele-com project starting on page 30 of the same issue. It’s a clever idea, and I remember my older brother building something similar back when I was just a nipper, although it was 9V battery-based and used the handsets only, not the whole phone. Graeme Rixon, RICTECH(NZ) Ltd. Notes about connecting to Micromite via Bluetooth I have been doing some more work with my Micromite project that you published in the September 2021 issue, and thought it would be a good idea to pass on some additional advice. When using the Bluetooth terminal on your Android phone, you can often connect OK, but the screen is blank. This is because the program auto-starts and is out of sync with the terminal. Powering the Micromite on and off a few times will sometimes get things back in sync, but the best way is to send Ctrl-C to the Micromite from the terminal. That will halt the auto-running BASIC program and return you a cursor input prompt. You then just type in RUN, and things will start at the beginning for you. The Bluetooth Terminal App recommended in the article has the facility to program a macro key. I have programmed my M1 key to send Hex 03, which is Ctrl-C. Tom Hartley, Allens Rivulet, Tas. SC siliconchip.com.au Australia’s electronics magazine December 2021  11 Big Brother is tracking you! Part Two: by Dr David Maddison Our article last month was about all the ways that companies or individuals can track you, both in your online activities and as you move around in real life, using your smartphone or another wireless device. This second part concentrates on the ways that governments monitor their citizens’ activities. Source: https://unsplash.com/photos/9wXvgLMDetA H ere are just a few examples of government surveillance of citizens. Since we “don’t know what we don’t know”, chances are there is a lot more going on behind the scenes. This sort of monitoring can benefit society if used to fight crime or help to fight pandemics, but that relies on proper oversight. Retention of metadata Under Australian law, records of all telephone calls and internet access (although supposedly not recordings of the audio or specific website access) must be kept by telcos and ISPs for a minimum of two years. Text messages are also included, although it’s not clear if the content is also recorded. The following metadata is retained, according to the website at siliconchip. com.au/link/abaf • Your name, address, and billing information • Your phone number or email address, and the phone number or email of the person you’re communicating with • The time, date and duration of a communication 12 Silicon Chip • Your IP address • The location of the communication equipment you use; for example, the closest mobile tower • The type of communication; phone call, text, or email • The amount of data uploaded and downloaded Almost any government department is allowed to access this information. According to the latest available information (2016), 60 departments were included; there are probably many more now. For the 2016 list, see the ABC article at siliconchip.com.au/ link/abag This seems to be a data-mining exercise, collecting data for its own sake, because criminal law enforcement agencies already had access to such data with appropriate warrants. No need for this massive data collection exercise was ever demonstrated. It seems that the main reason that website traffic and browser history was excluded was the vast amount of storage required to do so. During discussions about the new laws, one ISP (iiNet) said that this would require 1000 terabytes per day of storage. Australia’s electronics magazine As much as various politicians and government agencies might want it, recording all phone calls would take considerably more storage. Weeping Angel Weeping Angel is a method devised by the US CIA and British intelligence to listen in on the microphones of smart TVs. It was described in the WikiLeaks “Vault 7” release of March 2017. The logo used for documents under Vault 7: https://wikileaks.org/ciav7p1/ siliconchip.com.au Fig.12: Malte Spitz’s recorded call data as seen at the interactive website siliconchip.com.au/link/abam You can explore the data at that site in various ways. It was collected over ten years ago and seems relatively tame compared to what is collected by both government and big tech firms today. The exploit created a ‘fake off’ mode to make it look like the TV was off, even though the microphone was listening. You can view part of the Weeping Angel user manual and notes at siliconchip.com.au/link/abah It only works with specific models of Samsung TVs. When it was brought to Samsung’s attention, they said they were urgently looking into it. It also required physical access to the TV and the insertion of a USB drive to ‘update’ the TV software/firmware. Also see the video titled “Smart TVs have a surveillance problem” at https:// youtu.be/KxjnjiVF8JE Apps and uses Bluetooth Low Energy to find other contacts within 10m. Several countries use GAEN. Australia does not, instead adopting Singapore’s open-source BlueTrace protocol (https://bluetrace.io/). Australia’s implementation is called COVIDSafe. It is designed to detect contacts that have been within 1.5m of the App user for 15 minutes or more. It is unclear why this App cost $8 million to develop, costs at least $75,000 per month to maintain and has had little use despite 7 million downloads. See siliconchip.com.au/ link/abaj Mass surveillance Electricity usage monitoring While you might not be surprised to hear of massive surveillance in the People’s Republic of China, are you aware that more than 691,000 CCTV cameras operate in London alone? According to US News, nine of the ten most surveilled cities in the world are in China (calculated as most cameras per head of population), but London comes in at number three. See siliconchip.com.au/link/abai Some people grow illegal drugs in suburban houses. The grow lights use a lot of electricity, so they usually bypass the electrical meters to avoid paying the large bills and avoid suspicion. Electricity companies can detect line voltage drops via smart meters around suspect properties, thus revealing the presence of a possible “crop house”. Contact tracing Authorities in Australia regularly monitor sewage to track drug use in various locations. They also look for DNA fragments corresponding to COVID-19 outbreaks. There is no reason they couldn’t or don’t look for other types of DNA either, including that of individuals. In Australia, drug use is monitored Both Apple and Google Android have contact tracing ‘infrastructure’ (the “Exposure Notification Interface” application programming interface [API]) built into the operating systems. This is known as Google/Apple Exposure Notification or GAEN. This API is used by contact tracing siliconchip.com.au by the Australian Criminal Intelligence Organisation under the auspices of the National Wastewater Monitoring program. Around 56% of the population is subject to such monitoring. It is not just restricted to illegal drugs; nicotine and alcohol are included as well. You can read their public reports at siliconchip.com.au/link/abak Location tracking Telcos or governments can determine the location of a mobile phone owner even if the phone is not in use, since a powered-on mobile phone is constantly communicating with nearby towers. At the very least, they will know the phone’s approximate location. Certain technologies allow for more precise triangulation. Sewage monitoring Australia’s electronics magazine The COVIDSafe app is used by the Australian Government for contact tracing. It is based on the Singaporean-developed open source BlueTrace protocol. December 2021  13 4G and 5G telephony can use advanced beamforming so that rather than a mobile tower transmitting omni-directionally, a pencil-like beam is directed to your specific phone. This gives more precise location data than tower triangulation alone. WiFi can also be used to determine the device’s location, as discussed last month. The data collected is used by the government and others. Malte Spitz sued a German phone company about location data his phone company kept on him (see Fig.12). He gave a TED Talk on the subject in 2012, which you can watch at siliconchip. com.au/link/abal Mobile phone data analytics Governments are known to use mobile phone data and analytics for the following pandemic-related purposes: 1. COVID-19 contact tracing with Apps (as mentioned above) 2. Using mobile phone location data Fig.13: movement data provided by Vodafone to the government before and after COVID-19 restrictions and published in the Sydney Morning Herald, 05/04/2020. to monitor individual compliance with movement restrictions 3. Using data analytics to understand the general movements of people during a lockdown 4. Hot spot mapping to analyse the movement of COVID-19 positive people See articles on these subjects in Australia at siliconchip.com.au/link/ aban (Sydney Morning Herald) and siliconchip.com.au/link/abao (AusDroid). The second article is about Vodafone handing over anonymised mobile phone movement data to the Australian government – see Fig.13. Sale of surveillance tools to Australian government According to the 2015 ABC news The fourteen eyes Fourteen Eyes refers to an agreement between the governments of 14 countries: Australia, New Zealand, Canada, the USA, the UK, Germany, France, the Netherlands, Belgium, Italy, Spain, Norway, Sweden and Denmark. The intelligence services of these countries collaborate and share information. The concern over this is that it’s often illegal for an intelligence agency to spy on the citizens of their own countries, as they exist mainly to prevent the operation of spies from overseas, and there is concern that they could abuse their powers otherwise. However, there’s little stopping the intelligence agency of country A from spying on the citizens of country B, then passing their findings on to the government of country A. In fact, there is growing evidence of this sort of activity, especially since the 2013 NSA leaks (see https://w.wiki/3xsV). This is the main reason why we suggest in the article that if you’re looking for secure online services, you look for those hosted outside of this group of countries. Of course, that’s no guarantee that nobody is spying on their services, but it does improve your chances that if someone is spying on the service, they are not passing that information back to members of our own government. Note that in no way does a desire for privacy imply any wrongdoing or intent of wrongdoing any more than does putting an old fashioned letter into an envelope (in most countries). Five Eyes (USA, Canada, UK, Australia, New Zealand) Nine Eyes (France, Netherlands Denmark, Norway) Fourteen Eyes (Germany, Sweden, Belgium, Italy, Spain) 14 Silicon Chip Australia’s electronics magazine siliconchip.com.au article at siliconchip.com.au/link/ abap several companies have tried to sell various spyware and tools to the Australian government. One example is the tool RCS or Remote Control System, it can “siphon off data and listen in on communications before they are encrypted”, and is made by an Italian company called Hacking Team. “Once a computer or mobile phone is infected the tool can read emails, switch on the microphone or camera on the device, identify passwords and record Skype calls”. For more information on RCS, see https://w. wiki/3xtV ECHELON When discussing privacy, the subject of ECHELON comes up frequently. It is a surveillance program operated by Australia, Canada, NZ, the UK and the USA (collectively known as Five Eyes). Its existence is well documented. In 2001, The Guardian reported that ECHELON is “a global network of electronic spy stations that can eavesdrop on telephones, faxes (now obsolete) and computers. It can even track bank accounts. This information is stored in Echelon [sic] computers, which can keep millions of records on individuals. Officially, however, Echelon doesn’t exist.” Theoretically, it is used for military and diplomatic intelligence and not against innocent persons, but there have been claims of abuse. Fig.14: the discontinued L3Harris Technologies StingRay II for interception of mobile phone communications. Source: www.engadget.com/2016-01-28california-secretly-listened-to-cellphone-calls-from-the-air.html ECHELON is said to use voiceto-text technology so keywords and context can easily be automatically determined. Presumably, this is common practice for interceptions done by other government agencies. That is pretty standard technology today. IMSI catchers IMSI (International Mobile Subscriber Identity) catchers are devices used by various law enforcement agencies (and conceivably criminals) that act as a fake mobile phone tower or “cell site simulator”. Thus, surveillance can be undertaken without cooperation from phone companies and with or (potentially illegally) without warrants. They use what is known as a ‘man-in-the-middle’ attack, where a phone user thinks they are connecting to an official, secure mobile phone tower or site, but they are actually connecting to an IMSI Catcher device. The device performs all the normal functions of a phone tower, but with the added “feature” of data collection. StingRay (see Figs.14 & 15) was a particular brand of IMSI catcher made by the US company now known as L3Harris Technologies. However, they discontinued sales and support of StingRay in June 2020. See the videos titled “The Stingray: How Law Enforcement Can Track Your Every Move” at https://youtu. be/wzSgLpNrr2E and “How Stingray technology works” at https://youtu.be/ HyONknZ_x_g Fig.15: a page from the manual of a nowobsolete StingRay, released online. You can find copies of the manual if you search for it. siliconchip.com.au Australia’s electronics magazine December 2021  15 L3Harris also made products such as Kingfish (a hand-carried version of StingRay), Harpoon (a device to enhance the capability of the StingRay), Amberjack, Arrowhead and Hailstorm. Apparently, a popular replacement for the L3Harris StingRay is the Octasic Nyxcell V800 PBU/F800 TAU. Many US Government departments have online contract bids to acquire this device (no picture is freely available). Other manufacturers of IMSI catcher devices include: • Ability Computers and Software Industries (Atos) • Boeing subsidiary Digital Receiver Technology’s ‘DRT’ devices (hence another name for these devices, “dirt boxes”) • Datong (Seven Technologies Group) • Gamma Group • Martone Radio Technology • Meganet Corporation • Octasic • PKI Electronic Intelligence • Rayzone • Rohde & Schwarz • Septier Communication These devices have been in use for decades. Information that they can collect includes: • A phone’s location • The IMSI or ESN (electronic serial number, a 32-bit number embedded in a wireless phone and also printed on it) and other identification details • Call metadata, such as who is being called and the duration • The content of voice calls and text messages • Websites visited They can also be configured to divert calls and text messages, edit text messages and spoof the identity of the origin of text messages and voice calls. These devices can also collect all phone IDs in a geofenced area. There is a PDF report about the extensive use or overuse of IMSI catchers in Canada and abroad: siliconchip. com.au/link/abaq In that report, some of the uses for these devices are quoted as follows: • Confirming the presence of a device in a target’s home before a search • Identifying an individual responsible for sending harassing text messages • Locating a stolen mobile device as a precursor to searching homes in the vicinity • Locating specific individuals by driving around a city until a known IMSI is found • Mounted on aeroplanes to allow the United States Marshall Service to sweep entire cities for a specific mobile device • To monitor all devices within range of a prison to determine whether prisoners are using mobile phones • Reportedly at political protests to identify devices of individuals attending • To monitor activity in the offices of an independent Irish police oversight body Operation Ironside, arresting criminals & Australia’s lack of privacy laws The story of Operation Ironside is a good illustration of how government surveillance can prevent crime and also how poor Australia’s privacy laws (and civil liberties in general) are compared to other democratic countries. The story begins in 2018 when an informant for the US Federal Bureau of Investigation (FBI) developed smartphone software called AN0M which supposedly provided anonymous, encrypted communications. It was quickly adopted by various criminal operations (see https://w.wiki/3xsU for more details). The informant supplied communications data to the FBI, who then shared it with the Australian Federal Police. This led to almost 300 arrests in Australia and over 800 worldwide. Many of the charges had to do with the importation and distribution of banned drugs, although apparently at least one murder plot was uncovered by the operation. The interesting part is that, despite there being many AN0M users in the USA, no arrests were made there as much of the ‘overheard’ messages would not be admissible in court as evidence, as that would require warrants to be issued approving the eavesdropping. For those warrants to be issued, there would have to be a valid reason to suspect the surveilled individuals were involved in criminal activity. It appears that Australian authorities do not have to operate under such strict rules. According to the ABC article at siliconchip.com.au/link/abb4, this is because Australia’s privacy laws are amongst the weakest of any democracy. As stated in that article, “… innocent parties’ data could be obtained, stored and used in ways that they would never have foreseen”. If there is just one lesson to take away from Operation Ironside, it’s that you can’t trust unknown third parties to uphold your privacy. If an App or service claims to be anonymous or encrypted, absent laws ensuring those things being true, you should assume they aren’t. And even if such laws do exist, those services could operate overseas, outside those jurisdictions. So you clearly need to know whom to trust. In fact, based on the information recently revealed by the Australian Federal Government at siliconchip. com.au/link/abb5, the Australian government will have even more power to monitor online activity. The various logos used in Operation Ironside (also known as Operation Trojan Shield), from leftto-right you have: ANOM’s app logo (AN0M or ANØM), the AFP’s logo for the operation and the FBI’s logo for the operation. See https://en.wikipedia.org/wiki/ANOM 16 Silicon Chip Australia’s electronics magazine siliconchip.com.au See also the comprehensive video titled “Catching IMSI Catchers” at https://youtu.be/eivHO1OzF5E In that video, it is stated that for US$1400, it is possible to build your own IMSI catcher, and while this is documented publicly, we don’t suggest you do as it is certainly illegal. However, it is clear that criminals could make their own IMSI capture devices. Further details on IMSI catchers can be found on the EFF’s website: siliconchip.com.au/link/abb6 Tower “dumps” As reported in the Sydney Morning Herald at siliconchip.com.au/link/ abas, Australian authorities use tower “dumps” to track criminals. A tower dump provides the “identity, activity and location of any phone that connects to targeted cell towers over a set span of time”. Old-fashioned listening at the exchange The Author recalls how the introduction of GSM (2G) to Australia in 1993 was delayed by about a year because the exchange equipment had to be modified to ensure authorities could intercept any conversation at will. This is despite the same exchange equipment being accepted in other countries, which therefore introduced GSM earlier. There is a contemporary article in the Australian Financial Review on this, at siliconchip.com.au/link/ab3d No doubt, this capability still exists and likely has been enhanced now. as the Australian Taxation Office or Australian Electoral Commission, according to www.passports.gov.au/ protecting-your-privacy but presumably any other agency that wants them can get them, including foreign governments in some cases. License and passport photos Finding patterns in aerial or satellite imagery Governments routinely digitise drivers’ licences and passport photos and put them in databases so, like it or not, your picture is in a national database. That means that you can be automatically recognised and tracked by camera systems with access to that database. Australian governments employ extensive facial recognition systems within a National Facial Biometric Matching Capability. Services include the Face Verification Service (FVS), the Face Identification Service (FIS), the National Driver Licence Facial Recognition Solution (NDLFRS) and “Other Face Matching Services may be added over time”. For more information on this, see the Australian government (OAIC) website at siliconchip.com.au/link/ abat Australian passport photos can also be shared among other agencies such Terrapattern was a project of The Frank-Ratchye STUDIO for Creative Inquiry with the purpose of matching patterns in satellite images. An image such as a tennis court is selected, then all similar-looking tennis courts from the satellite imagery database are found. The software uses a Deep Convolutional Neural Net (DCNN) to assist with image recognition. We are unaware of this project still being active. See Fig.16 and the video titled “Terrapattern (Overview & Demo)” at https://youtu.be/VHv5W7Ei80s An example of use for financial or state-based intelligence is finding and examining all images of oil storage tanks. As the oil level changes, so does the floating roof of the tank. By examining the shadows cast, it is possible to determine the oil levels of tanks in a particular region, which could influSC ence the price. Fig.16: a Terrapattern search of objects in satellite imagery that look like oil tanks to determine oil level from shadows. This is a screengrab from the YouTube video at https://youtu.be/VHv5W7Ei80s siliconchip.com.au Australia’s electronics magazine December 2021  17 The Humm Audio A Like a hummingbird, this miniature amplifier is strong, delivering up to 60W into 8W 8W or 100W into 4W 4W. It is ideal for building multi-channel amplifiers for R eaders frequently ask us for advice on building amplifiers with more than two channels. We’ve published many hifi amplifier module designs over the years, but mainly they have been designed for maximum power and minimum distortion, resulting in modules that will only fit one or two per case (unless you use a huge case!). We have published amplifier designs using all-in-one IC ‘chip’ amps like the LM1875T. They are always quite compromised, both in terms of maximum power output (typically topping out at around 30-40W) and performance, with distortion and noise figures far worse than a discrete amplifier. This design offers an excellent compromise between the two. It’s cheaper and easier to build than our best hifi amplifiers while still delivering plenty of power with very good performance. And because it’s so compact and has modest power supply requirements, you can quite easily jam half a dozen (or more!) of these into a reasonably-sized chassis. We designed these for driving multiway loudspeaker systems using an active crossover to split the signals into frequency ranges to suit each driver. This approach needs one amplifier per driver (woofer, tweeter etc) but you generally don’t need as much power per amplifier, since they are working together. Initially, we looked at using small, low-cost Class-D amplifier modules which could deliver 30-50W. After quite a bit of searching, we concluded Features Specifications ● Low distortion and noise ● Extremely compact PCB ● Fits vertically on a 75mm heatsink and can be stacked in a 2RU case ● Produces specified power output continuously with passive cooling ● All through-hole parts ● Low in cost, simple to build ● Onboard DC fuses ● Output over-current and short circuit protection ● Clean overload recovery with low ringing ● Clean square wave response with minimal ringing ● Tolerant of hum & EMI fields ● Quiescent current adjustment with temperature compensation ● ● ● ● 18 Silicon Chip ● ● ● ● ● ● ● that there was nothing readily available with distortion performance within an order of magnitude of what we’d call hifi. Many smaller Class-D amplifiers exhibit high-frequency distortion above 0.5%, worse than many decent loudspeaker drivers! Our benchmark for high fidelity amplifiers is the Ultra-LD Mk.4 (August-October 2015; siliconchip. com.au/Series/289). If we could fit six of those into a box with a power supply, we would be set! But as mentioned above, they are far too large. The answer was to shrink the design as much as we could without making too many compromises. The result is the Hummingbird amplifier module that packs a surprising punch for its size, while keeping Output power (±32V rails): 100W RMS into 4W, 60W RMS into 8W Frequency response (-3dB): 1Hz to 150kHz Signal-to-noise ratio: 118dB with respect to 50W into 4W Input sensitivity: 1.2V RMS for 60W into 8W; 1.04V RMS for 100W into 4W Input impedance: 22kW || 1nF Total Harmonic Distortion (8W, ±32V): <0.008%, 20Hz-20kHz, 50kHz bandwidth 32W (see Figs.2 & 6) Stability: unconditionally stable with any nominal speaker load ≥4W Power supply: ±20-40V DC, ideally ±34V DC from a 25-0-25 transformer Quiescent current: 53mA nominal Quiescent power: 4W nominal Output offset: typically <20mV (measured) Australia’s electronics magazine siliconchip.com.au mingbird Amplifier applications like surround sound or when using an Active Crossover (like the one we presented last month). It can trace its heritage back to our UltraLD family, making only a few compromises in being shrunk to a fraction of its original size. It even has output protection! Image Source: https://pixabay.com/photos/hummingbird-bird-flight-wings-2139279/ many of the low-distortion characteristics of the Ultra-LD amplifiers from which it takes inspiration. It can achieve up to 60W into 8W or 100W into 4W with distortion below 0.0008% at 1kHz and less than 0.008% all the way up to 20kHz. That’s way better than “CD quality”. Design While the physical PCB bears little resemblance to the Ultra-LD series, a comparison of the circuit diagrams (Fig.7) will show how many similarities there are between the Hummingbird and its larger siblings. The principal changes are: • There is only one pair of output transistors, rather than two. • We’re using less expensive NJW21193/4 output transistors. • The maximum supply rail voltages have dropped from ±57V to ±40V. • The PCB width has been reduced from 135mm wide to 64mm – less than half. • Simplification lets us use throughhole components exclusively. The width of the PCB is defined by the two output devices and thermal compensation transistor. This is also a neat fit for the emitter resistors By Phil Prosser required for a stable operating bias point. Despite their relatively large size, we have retained the DC rail fuses in this design, as they form an important protective layer for the amplifier in case something goes wrong in use. The SOA protection is tightly coupled with the output stage and sits between this and the Voltage Amplifier (VAS). The VAS and Driver come next, and sit between the fuses, again with little room to spare. At the front end of the board is the input stage. How the various sections of the amplifier fit on the PCB is shown in Fig.1. Fig.1: this depiction of the Hummingbird PCB is at 90% of life-size and shows the purpose of each set of components. The input stage is responsible for setting the gain and distortion cancellation while the VAS & drivers buffer the signal from the input stage to provide suitable drive for the output transistors. The SOA Protection circuitry keeps the output transistors within their ‘safe operating areas’. siliconchip.com.au Australia’s electronics magazine December 2021  19 Because we are only using one output device per side, we have chosen a robust device with a generous safe operating area (SOA). Few devices are sturdier than the NJW21193G/NJW21194G (or their beefier MJL21193/4 siblings). These are rated at 16A, 250V and 200W. We decided to add output SOA protection to the amplifier that monitors the output current and voltage and shuts off the output in case of a short circuit or severe overload. This protects the amplifier from all but the worst abuse. Calculations confirmed that using a mains transformer with a 25-30V AC secondary providing rail voltages of ±35-42V would be safe with a single pair of output devices into 4W, 6W or 8W, delivering 60W into 8W loads and 100W into 4W loads. With a 25V transformer, that’s reduced slightly to 50W for 8W. We have not diverted very far from the Ultra-LD series design for the remainder of the amplifier design. This is because the topology of the Ultra-LD amplifier, which is basically the “blameless” amplifier (as it is dubbed by Douglas Self), just works. The innovation in this project is more about simplification and minimisation. No doubt using SMDs would have let us make the PCB less, err, packed. Still, we managed to fit all the required through-hole components into an area of just 88 by 64mm. That will easily fit standing on its side in a standard two rack unit (2RU) high case, and assembly is not especially difficult. Performance We took total harmonic distortion Fig.3: a scope plot of the amplifier’s output waveform into an 8W resistive load, driven into clipping. You can see there’s a tiny bit of ‘sticking’ to the negative rail as it comes out of clipping, but not enough to be concerned about. 20 Silicon Chip Fig.2: total harmonic distortion (minus noise) plots for the Hummingbird at two different power levels: 36W (red) and 10W (blue). The other curves show the test results with various combinations of output transistors, driver transistors and, in one case, a different VAS transistor (BD139, pink curve). Regardless of which devices you choose, the performance is pretty good. (THD) measurements of the prototypes at 10W and 35W into 8W by powering it from a bench supply, shown in Fig.2. The 35W measurement required using a 40dB attenuator with our test equipment, while the 10W level only needed a 20dB attenuator. That is why the distortion results at 10W look so much better than at 35W. Given that the shapes of the two curves are very similar, it’s likely that the actual performance of the amplifier is closer to the 10W figures, even up to its maximum 60W power output. We can confidently say that this amplifier generates very low distortion levels, and at 10W, is below 0.002% THD over much of the audio range. Note that Fig.2 also shows partial distortion curves for various alternative output/driver/VAS transistors, and we will explain those options a bit later. The amplifier behaves well at clipping. The most common problem is the output ‘sticking’ as the amplifier exits clipping from the negative rail, when the VAS transistor comes out of Fig.4: this time, the amplifier has been driven into clipping with a 3W resistive load, representing pretty much the worst-case situation it will have to deal with when driving a real 4W (nominal) loudspeaker. Once again, the recovery from clipping is fine. Fig.5: we fed a square wave signal (orange) into the Hummingbird and connected its output to a 3W resistive load (harsh, we know). It handled this very well, with no sign of overshoot or undershoot; it’s a very well-behaved amplifier. Australia’s electronics magazine siliconchip.com.au Fig.6: one of the many spectral plots we produced as part of the performance tests. You can see the THD readings of the input (red) and output (blue) signals towards the bottom. You can also see all the harmonics of both signals in the central area. The test signal is at 1kHz, so the first harmonic is at 2kHz, third at 3kHz etc. The amp’s output was passed through a 40dB attenuator, reducing the fundamental to -15dB and dropping the measured noise floor to that of the instrument. saturation. The Hummingbird behaves well coming out of clipping, as shown in Figs.3 & 4. We also tested with a square wave signal, and the result is in Fig.5. There is not a lot to show here; it generates a bandwidth-limited square wave output as shown, with no overshoot and minimal undershoot. Finally, Fig.6 shows one of the spectral plots taken while gathering the measurements for Fig.2. The left channel is connected to the output of the amplifier via an attenuator, while the right channel is monitoring the signal into the amplifier. As you can see, the distortion at the output is hardly any higher than the input signal, and the second and third harmonics are roughly equal at around -110dB. The 22kW input resistor is selected to match the 22kW feedback resistor so that each side of the differential amplifier formed by PNP transistors Q7 and Q8 has matched DC input impedances. Assuming that these transistors have equal current through each leg and similar hfe, the offset voltages at the bases of Q7 and Q8 will be about the same. This should ensure a low output offset voltage on the amplifier. We measured less than 20mV on our prototypes. We have specified BC556 transistors for Q7 and Q8, although you could use low-noise BC560 devices if you can find them. These are commonly available and perform well in this application. 100W emitter degeneration The Hummingbird Amplifier is built on a PCB measuring 64 x 88mm. The Amplifier can be built with multiple configurations of transistors. For example, this photo uses MJE15032/3 transistors for Q4 & Q12. These could be replaced with BD139/140 transistors respectively. See Tables 1-3 for more detail. Circuit description Fig.7 shows the Hummingbird circuit. A 220kW resistor biases the input signal at CON2 to 0V DC. The input signal passes through a 10μF bipolar capacitor and then a 100W resistor shunted by 1nF and 22kW to the lownoise signal ground. This connects to the output ground via a 10W resistor. The 10μF and 22kW combination at the input sets the -3dB low-frequency cutoff point below 1Hz. siliconchip.com.au Australia’s electronics magazine December 2021  21 Fig.7: the Hummingbird amplifier circuit is pretty standard if a bit minimalist. It has a lot in common with our previously published, higherpower amplifiers like the SC200 and Ultra-LD series. Note NPN transistor Q17, which has been added to protect Q14 during negative clipping excursions and the SOA protection transistors, Q6 & Q10, with three resistors each to set the I/V limit slope and intercept. resistors are used for Q7 and Q8. These assist with achieving balance and linearity in the differential amplifier. This reduces its sensitivity to transistor and temperature variations. The input stage operates with 3mA of bias current. This is set by the 220W resistor in the emitter leg of PNP transistor Q3, which serves as a constant current source. The keen-eyed will note that we have omitted a resistor from the previous design, which was between the constant current source and the differential amplifier. Our lower voltage rails mean this is not necessary, as Q3 can handle the resulting 100mW dissipation. The collector legs of the differential amplifier feed into a current mirror made using NPN transistors Q15 and Q16. A current mirror works by exploiting the fact that with a matched set of transistors at the same temperature, the Vbe (base-emitter voltage) relationship vs current will be the same. So by connecting the bases of Q15 and Q16, and putting the same resistance in their emitter circuits, if we drive 1.5mA through Q16, Q15 will similarly seek to conduct 1.5mA as it has the same base-emitter voltage. This ensures that the differential pair of Q7 & Q8 operates with the same current in each leg, which means it operates optimally as a linear differential amplifier. The output of the differential amplifier is a current that flows into the base of NPN transistor Q13. If the amplifier output is higher than the input, the input to Q8 increases, which reduces the current into Q16. Because the current mirror ‘tries’ to keep the current through Q15 and Q16 the same, this ► excess current flows into Q13’s base. Q13 forms part of a quasi Darlington transistor pair with Q14, which ultimately drives the amplifier output. These transistors together form the voltage amplifier stage (VAS). It transforms the current from the front end into a voltage. Q14 is a KSC3503DS transistor, which is specialised for this sort of application. These are available from Mouser, Digi-Key, element14, RS etc. The VAS transistor needs to have a very low Cob or output capacitance. There are not many really suitable devices being made these days, most likely as the best VAS transistors were also video amplifier transistors for cathode ray tube (CRT) based monitors, which have gone the way of the Dodo! We used the BF469 video transistor here in the past, but they are now obsolete. The load on the VAS is the constant current from PNP transistors Q1 and Q2, which is set to about 8mA, plus the current required to drive the output stage. Between Q2 and Q14, we have NPN transistor Q9 and its base biasing resistors. This forms a simple ‘Vbe multiplier’ that allows us to set the voltage between the bases of output stage and driver transistors Q4, Q5, Q11 and Q12. These are arranged in standard emitter-follower connected pairs. The amplifier must operate in Class-AB for good performance, where Fig.8: four common amplifier classes; Class-C is mainly used for RF, not audio, ► where distortion is less of a concern. Class-A has a single transistor that varies its conduction over the whole cycle, while the other three classes use complementary pairs. In Class-B, one device conducts for the positive half of the cycle; the other conducts during the negative half. Class-AB is like Class-B except that both devices conduct when the output is near 0V (the purple area is where they overlap), while for Class-C, neither device conducts in the crossover zone. 22 Silicon Chip Australia’s electronics magazine siliconchip.com.au both the positive (NPN) and negative (PNP) output devices are conducting for output voltages around the 0V crossover point, as shown in Fig.8. We want to bias the amplifier to draw about 50mA in the quiescent state as this gives the best output stage linearity around the crossover point. To achieve this, we need to set a ‘constant’ voltage to bias the four base-emitter junctions at just over their turn-on voltage (about 0.6V each), for a total of around 2.4V. But the base-emitter threshold voltages of Q4, Q5, Q11 and Q12 all vary with temperature, so Q9 is mounted on the same heatsink as Q5 and Q11, siliconchip.com.au and Q9 is used to multiply its own Vbe voltage using a 390W fixed resistor and potentiometer VR1. This way, the bias voltage will track the Vbe voltages of those two transistors, giving a mostly constant bias current. When properly adjusted, VR1 will be about 130W. Q9’s base-emitter voltage is across this resistance, around 0.6V, giving about 4.6mA through VR1 and also the 390W resistor. That gives 1.8V (390W × 4.6mA) between Q9’s base and collector, for a total of 2.4V (0.6V + 1.8V). Our output stage is a single pair of transistors, Q5 & Q11. The NJW21193/4 types, as stated earlier, have been Australia’s electronics magazine selected for their large safe operating area. These are driven by MJE15032/33 driver devices, as there is not enough current available from the VAS to drive them directly. The output devices both have 0.22W resistors in series with their emitters, providing a small amount of negative feedback for their bias currents. The driver devices are capable of much higher current and dissipation than demanded in this application. However, they are freely available and reasonably priced, so they suit this application well. They do not dissipate enough power in this application to require heatsinking. December 2021  23 Fig.9: SOA curves for all the output devices you can use in the Hummingbird, plus load lines for 8W purely resistive and 45° reactive loads (representing a worst-case loudspeaker). This shows that all the output devices are safe for driving such loads with the recommended supply voltages, except perhaps the TIP35/36, so it’s probably best to avoid those if possible. However, suppose you are pushing your luck by increasing the rail voltage or driving very low impedances with continuous waveforms, or you wish to achieve ideal bias tracking. In that case, you might benefit from fitting them to the heatsink (or the back of the output devices) on flying leads. Ideally, we would have mounted them on the main heatsink so that their Vbe voltages track those of the output devices, as Q9 will multiply its own Vbe changes by a factor of four. We did not do that, to keep this module as compact as possible. The driver transistors still heat up and cool down as the load changes, which provides some thermal tracking, but it won’t be exact. Fig.10: a similar plot to Fig.9 but this time, the load lines are for 4W resistive/reactive loads and we’ve eliminated those output devices that we don’t recommend for driving 4W loudspeakers. All three options are pretty safe; the MJL3281A/MJL1302A pairing comes pretty close to the reactive load line, but the SOA protection circuitry is there to save the day if necessary. The result is that under transient application of a heavy load, the output stage bias will tend to decrease slightly as the module gets hot delivering a significant amount of power. It does not experience thermal runaway, nor does the performance change due to this change in bias, so it is a worthwhile compromise to keep the module compact. SOA protection Because we are using a single pair of output devices, we feel it prudent to protect them against unexpected overload or short circuits. Shorting the output of a typical amplifier often leads to the failure of output devices, driver transistors and ultimately the fuse, often in that order. We get around that by adding some basic safe operating area (SOA) limiting components. The SOA curves for each pair of recommended output devices (taken from their data sheets) are plotted in Figs.9 & 10, along with curves representing the maximum specified output power being delivered into purely resistive and reactive loads, the latter representing the worst-case loudspeaker load. As you can see, except for the TIP35/36 pair, all devices will be within their SOAs under these conditions. However, some loudspeakers can have significant impedance dips at specific frequencies that could cause the transistors to operate outside their safe areas, and also Table 1 – alternative output transistors NPN output PNP output SOA protection resistors Comments & limitations Status NJW21194G NJW21193G 18kW 820W 220W Performance as presented Verified MJL21194 MJL21193 22kW 750W 220W Performance as presented; THD <0.001% at 1kHz with MPSA42 VAS Verified FJA4313 or 2SC5242 FJA4213 or 2SA1962 22kW 470W 270W Limit to 25V AC transformer if driving difficult 4W loads Verified 2SC5200 2SA1943 18kW 560W 220W Performs as specified Verified MJL3281A MJL1302A 18kW 820W 220W TIP35B/C TIP36B/C 27kW 1kW 390W Limit to 25V AC transformer, prefer 8W load. Surprisingly good performance Verified TIP3055 TIP2955 12kW 680W 270W Limit to 25V AC transformer and 8W load Not checked 24 Silicon Chip Not checked Australia’s electronics magazine siliconchip.com.au ► Fig.12: we deliberately overdrove the amplifier by connecting its output across a load of just 1W and fed it with a single sinewave pulse. This causes the output transistors to deliver so much current that it triggers the SOA protection circuitry. You can see from the bottom trace how it limits the output voltage/current to protect the transistors. accidents can happen with the wiring accidentally shorting together etc. Fig.11 shows the same SOA curves as Figs.9 & 10 but also adds dashed “SOA protection” lines. These are the limits we’ve chosen to ‘program in’ for each pair of output devices to ensure they stay within their SOAs. The effect of driving the Hummingbird into a 1W load is shown in Fig.12. The input signal is at the top, while the ‘clipped’ output waveform below shows the protection kicking in. This will not save you from ultimately overheating the output transistors, but it will prevent the immediate loss of magic smoke. Some people claim that this type of protection degrades the amplifier’s performance, but the measured specifications speak for themselves. Fig.11: this shows all the output transistor SOAs again, as well as the SOA protection lines (dashed). While the protection lines are straight, they’re positioned to stay below the SOA curves in almost all cases, so the amplifier can’t drive the transistors outside of their SOA curves. The SOA protection lines for the NJW21193G/ NJW21194G and MJL3281A/MJL1302A are identical (green dashed line) since, despite being different curves, they cross over at a critical point. ► To understand how the SOA protection works, consider the top half, based on NPN transistor Q6 and diode D1 plus three resistors: 18kW, 820W and 220W. In normal operation, the voltage across the 0.22W emitter resistor of Q5 is less than 0.6V. Ignoring the extra resistors for now, this means that Q6 is biased off and has no effect. Under fault conditions, the voltage across the 0.22W resistor increases to the point that Q6 starts to switch on. This diverts current from the base of driver transistor Q4 to the output, starving the driver of base current. This, in turn, starves the output device of base drive until the output current reduces to the point that Q6 is no longer switched on so hard. This creates a local feedback loop that limits the output current, thus protecting the output stage. Diode D1 is included so that the opposing current protection circuit is not reverse-biased by heavy output loads. In the absence of the three extra resistors, Q6 would switch on at an output current of about 3A (0.6V across a 0.22W resistor). This is too early, so to allow more current, the 820W and 220W resistors form a voltage divider with a division ratio of 0.21. So a current of about 13A through the emitter resistor is required to turn the over-current protection on. Without the 18kW resistor, the current limit will be the same regardless of the output voltage. Adding that resistor injects more current into the voltage divider formed by the other two resistors, so that at low output Table 2 – alternative driver transistors NPN driver PNP driver Comments Status MJE15032 MJE15033 As specified (MJE15034 & MJE15035 have not been tested but should be similar) Verified MJE15030 MJE15031 These perform well with 8W and 6W loads. At 3W, distortion increases faster than the specified devices, but they are still a fair choice Verified TIP31B/C TIP32B/C Performs close to specifications. With 3W loads, distortion increases faster than the specified devices, but they are still a fair choice Verified BD139 BD140 Install in opposite orientation (ECB vs BCE pinout). The -16 gain group parts are the best choice. Limit to 25V AC transformer Verified MJE350 MJE340 Install in opposite orientation (ECB vs BCE pinout). Not ideal. Marginal on maximum current. Limit to 8W and 25V AC transformer Not checked siliconchip.com.au Australia’s electronics magazine December 2021  25 Table.3 – alternative VAS transistors NPN VAS Comment Status KSC3505DS As specified Verified BF469 As specified Verified BD139 Slightly elevated distortion, but a surprisingly good performer – rumour has it that there are many “types” of BD139, so ‘your mileage may vary’. Verified MPSA42 Pinout is different. Measured THD <0.001% at 1kHz with MJL21193/4 output transistors. More negative rail “sticking” than KSC3505DS, but not excessive Verified voltages, more current is injected, and the current limit kicks in earlier. This results in the SOA protection being “sloped” to fit the SOA of the output devices, and allowing more current at high output voltages, because the voltage across the devices is lower. Thus they dissipate less power for the same current. Output device selection The pinout of the output devices is very common. The Hummingbird delivers the measured performance with the parts specified, but we have checked that the amplifier works properly with a range of other output transistors. You do need to change the SOA protection resistor values, though, as per Table 1. You also have options for the driver transistors (Table 2) and VAS transistor (Table 3). Construction All parts are through-hole, and they fit on the 64 x 88mm, double-sided PCB coded 01111211, shown in Fig.13. The parts are closely spaced but not too tight. We have kept the pad sizes generous to make soldering easier. Before we continue, we strongly advise you to use transistors from a reputable supplier. There are cheap transistors on internet auction/sale sites. Do not be tempted by these. Fakes are prolific, even in surprisingly simple devices. All the devices recommended for this amplifier are available at reasonable prices from major suppliers. Start by fitting all the small resistors and diodes – make sure the orientations of the diodes match what’s shown in Fig.13 and on the PCB silkscreen. Follow with the trimpot, orientating its adjustment screw as shown. This is critical as we need to be able to set the quiescent current to a minimum before the module is first powered up. 26 Silicon Chip Next, mount the input and output connectors. We have used parts with the common 5/5.08mm spacing on these (except the input, a 2.54mm-pitch header). You should consider how you will be mounting the modules before choosing either screw terminals or pluggable connectors. Access to a screw terminal may be obstructed in some arrangements, so in that case, use pluggable connectors. Now install all the non-polarised capacitors. Fit the MKT parts close to the PCB. Make sure that you use a 100V-rated device for the 220pF capacitor. Follow with the 5A fuses and their clips. We find it easiest to put the fuses in their clips and then solder that as an assembly to the PCB. This ensures everything is well-aligned. Fit the electrolytic capacitors next, noting that they must all be installed with their + (longer) lead to the left when the PCB is orientated with the output devices at the top. Ensure that you have adequate voltage ratings on these parts (ie, at least what is specified in the parts list). Now install the TO-92 transistors. It is worth finding matched pairs for Q7 & Q8 and Q9 & Q10, if you can. To do this, check the hfe figures of a handful of each type. Select pairs that have reasonably similar hfe measurements; within 10% is fine. Also, try selecting pairs that have high hfe figures compared to the others. With the BC549 and BC556, an hfe figure below 100 is cause to throw the part in the bin, although such a low reading is rare indeed. Now is a good time to mount the remaining resistors. The only ones that get warm are the 0.22W output stage emitter resistors, and that’s only when delivering full-power sine waves from the amplifier, which will not happen with musical material. But it is still good practice to mount these a few millimetres proud of the PCB. The PCB will accept standard 5W cast resistors, but we really liked the look and fit of some smaller resistors we got from Mouser (see the parts list). They need to have a rating of at least 3W in this application, so 5W is quite conservative. Making inductor L1 The output inductor is made from 0.8mm enamelled copper wire (ECW) as follows: 1. Find a mandrel that is a bit over 10mm in diameter and has a slight chamfer to it so that once complete, you can push the inductor off. We used a large ‘Sharpie’ brand permanent marker. 2. Put masking tape around this mandrel with the sticky side facing outwards. Fig.13: building the Hummingbird is straightforward; fit the components to the PCB as shown here. Watch the orientations of all diodes, transistors and electrolytic capacitors. For the TO-220 and TO-126 devices, the metal tabs face as shown here (if your TO-126 device lacks a metal tab, it would typically be opposite the side with writing on it). Don’t forget that if any of your transistors are substitutes for the recommended devices, they will have different part codes than those shown here – see Tables 1-3. Australia’s electronics magazine siliconchip.com.au Parts List – Hummingbird (for one amplifier) 1 double-sided PCB coded 01111211, 64 x 88mm 1 split rail power supply delivering ±20V to ±40V DC (eg, 15-28V AC mains transformer, bridge rectifier, filter capacitors, mains socket, mains-rated wiring, heatshrink tubing etc) – see Fig.15 3 2-way 5/5.08mm pitch mini terminal blocks (CON1, CON3, CON4) 1 2-way polarised/locking pin header (CON2) 4 M205 fuse clips (F1, F2) 2 5A 5mm ceramic fuses (F1, F2) Altronics kit will be available 1 1m length of 0.8mm diameter enamelled copper wire (L1) Altronics has announced that they will be 1 500W vertical or side-adjust multi-turn trimpot (VR1) making a kit for this project, code K5158. 2 TO-3P insulating kits (washers and bushes) It should be available late November/early 1 TO-126 insulating kit (washer and bush) December. Check their website or in-store 3 M3 x 25mm panhead machine screws to find the kit price (not available at the 3 flat washers to suit M3 screws time of going to press). 3 crinkle washers to suit M3 screws 3 M3 hex nuts 2 blown 5mm fuses (for testing, or purposefully blow 100mA fuses) 1 heatsink, type depending on intended application (we used one Altronics H0545 for six modules) 1 small tube of superglue 1 5cm length of masking tape Semiconductors 5 BC556 65V 100mA PNP transistors, TO-92 (Q1, Q3, Q7, Q8, Q10) 1 MJE350 300V 500mA PNP transistor, TO-126 (Q2) [Altronics Z1127, Jaycar ZT2260] 1 MJE15032G or MJE15034G 250V/350V 8A NPN transistor, TO-220 (Q4) [element14 9556621, Digi-Key MJE15034GOS-ND, Mouser 863-MJE15032G] 1 NJW21194G or MJL21194 250V 16A NPN transistor, TO-3P (Q5) [Jaycar ZT2228, element14 2535656, Digi-Key NJW21194GOS-ND, Mouser 863-NJW21194G] 3 BC546 65V 100mA NPN transistors, TO-92 (Q6, Q13, Q17) 1 BD139 80V 1A NPN transistor, TO-126 (Q9) [Altronics Z1068, Jaycar ZT2189] 1 NJW21193G or MJL21193 250V 16A PNP transistor, TO-3P (Q11) [Jaycar ZT2227, element14 9555781, Digi-Key NJW21193GOS-ND, Mouser 863-NJW21193G] 1 MJE15033G or MJE15035G 250V/350V 8A PNP transistor, TO-220 (Q12) [element14 9556630, Digi-Key MJE15035GOS-ND, Mouser 863-MJE15033G] 1 KSC3503DS 300V 100mA NPN transistor, TO-126 (Q14) [element14 2453955, Digi-Key KSC3503DS-ND, Mouser 512-KSC3503DS] 2 BC549 30V 100mA NPN transistors (Q15, Q16) 3 1N4148 75V 250mA small signal diodes (D1-D3) Capacitors 1 220μF 25V electrolytic [Altronics R5144, Jaycar RE6324] 2 100μF 50V 105°C electrolytic [Altronics R4827, Jaycar RE6346] 2 47μF 50V low-ESR electrolytic [Altronics R6107, Jaycar RE6344] 1 10μF 50V low-ESR electrolytic [Altronics R6067, Jaycar RE6075] 1 10μF 50V non-polarised electrolytic [Altronics R6560, Jaycar RY6810] 1 220nF 63V MKT [Altronics R3029B, Jaycar RM7145] 5 100nF 63V MKT [Altronics R3025B, Jaycar RM7125] 1 22nF 63V MKT [Altronics R3017B, Jaycar RM7085] 1 1nF 63V MKT [Altronics R3001B, Jaycar RM7010] 1 220pF 100V NP0/C0G ceramic [eg, element14 2860112, Digi-Key 445-173535-1-ND, Mouser 810-FG28C0G2A221JNT6] Resistors (all 1/4W+ 1% metal film axial unless otherwise stated) 1 220kW 5 100W 0.5W or 0.6W 1% metal film 2 22kW 1 82W 2 18kW 2 68W 2 3.9kW 2 47W 0.5W or 0.6W 1% metal film 3 2.2kW 1 39W 1 1.2kW 1 15W 1W 2 820W 1 10W 1 390W 2 10W 5W 10% (for testing) 4 220W 1 4.7W 1W 2 0.22W 5W 5% [element14 1735119, Digi-Key BC3440CT-ND, Mouser 594-AC050002207JAC00] siliconchip.com.au Australia’s electronics magazine December 2021  27 3. Placed a bend in the enamelled copper wire (ECW), 30-40mm from the end, and wind nine turns onto the masking tape. 4. Put a few drops of super glue on the ECW. Don’t worry if it gets on the masking tape, but you probably don’t want to get it on your mandrel! 5. Give this a minute to set, then wind another layer on top of the first nine turns. You might only be able to get eight more in; that is OK. Add more superglue and again allow it to set. 6. Add the final winding of nine turns over that and glue again. 7. Push the inductor off the mandrel. Don’t be scared to give it a solid push. 8. Tease the masking tape from inside the inductor; we used longnose pliers. Then we added some extra super glue. 9. Trim the ends, scrape the enamel off them and mount it to the PCB above the 4.7W resistor as shown. Finishing construction Now fit the remaining transistors: solder Q2, Q4, Q12 & Q14 directly to the PCB. The BD139, NJW21193 and NJW21194 devices that mount on the main heatsink (Q5, Q9 & Q11) come last. Before proceeding, check your mounting arrangements and ensure that you load these at the right height for mounting on the main heatsink. The best way is to mount these transistors to the heatsink using the insulating kits and machine screws, bend their leads to fit the board and then solder them. It’s ideal if you can tap the heatsink to accept the screws, but if not, drill through between the fins and use long screws and nuts. Adjustment & testing It is critical that the bias adjusting potentiometer is set to maximum resistance so that the initial bias current is very low. Do this by turning it clockwise a minimum of 20 turns. Check with a multimeter that there is close to 500W between the cathode (striped end) of diode D3 and the right-hand end of the 390W resistor, just to the left of Q11. Do this now as, if you forget, you might blow the fuses when you power it up, and fuses aren’t always fast enough to protect semiconductors! 28 Silicon Chip Fig.14: route the wiring to each module like this to ensure you get the stated performance. Current flowing through these wires will cause magnetic fields, which affect the operation of components on the amplifier. Routing the cables this way keeps those magnetic field strengths low. Once you’ve run them, use cable ties and cable clamp to hold them in place and keep everything neat. You can do some initial testing without mounting the amplifier to a heatsink. This test will check that the amplifier is operational. Remove the 5A fuses from the board and install the test (blown) M205 fuses with 10W 5W resistors soldered across them. We refer to these as “safety resistors”. Connect a voltmeter between the output and ground, set to a 200V range (or similar). Connect another voltmeter across one of the 10W resistors, set to a 20V range or similar. If you only have one meter, run an initial check monitoring the output voltage only. With the input to the module disconnected, apply power. Anything over about ±15V is fine. If you can, set the current limit on the power supply to about 100mA. Check that the output voltage settles to 0V ±50mV. We built 14 test units, and all were within that range. Also check that the voltage across the 10W Australia’s electronics magazine safety resistor is less than 1V. If either of these tests fail, immediately power it off and check for the cause. Have you got the bias pot set at the right end of its travel? Are all the capacitors in the right way around? Do you have a signal feeding the input? If so, disconnect it. Are all the transistors and diodes in the right places and the right way around? Check that those output devices are in the right spot! Is your power supply delivering both positive and negative rails, and do you have the ground connected? Setting the bias This requires the amplifier to be mounted to a heatsink with appropriate insulators for the output devices and Vbe multiplier transistor. Power it up and adjust the bias by turning potentiometer VR1’s screw anticlockwise while watching the voltage across siliconchip.com.au The Amplifier can be cleanly mounted to a 75mm heatsink as shown above. The SOA protection resistors are missing as we wanted to compare the performance with and without them. After which you can daisy-chain them together to form a larger system such as a six channel setup shown adjacent. This setup was mounted in a 2U rack case. the 10W resistor. Nothing will happen for quite a few turns; then, the bias current will rapidly increase. Adjust this to achieve 500mV across the resistor. Allow this to settle and readjust. It will take a while to settle, depending on your mounting arrangement this should be done with the full supply voltage applied (ie, the final voltages you intend to use). Re-install the 5A fuses, and you are ready to go. You can check the bias later by measuring the voltage across the 0.22W resistors; you should see 10mV across each. If you’re mounting multiple modules on a heatsink sideways as we did, the side-adjust style trimpot specified makes this quite easy. Installation To minimise distortion to the levels presented requires careful attention to layout and the power supply wiring. Our recommended wiring layout per module is shown in Fig.14, and the recommended power supply configuration is shown in Fig.15. The wiring from the main supply capacitors should have the positive, negative and ground wires twisted together. The output should fold back toward the output devices, run parallel to the 0.22W output resistors, then follow the power wires. The output wire should follow the power wires back past the power supply and pick up a ground wire, minimising the loop area created, then run as a pair from there to the speaker terminals (see above). Ensure that the power supply has a ‘star Earth point’ from which you connect to the input ground, the amplifier ground and the speaker output ground. Also check that the way you connect the rectifier and its ground connection to the capacitors does not inject noise onto your star Earth point. Connect the input shielded cable screen to the star point. Make sure all connections are secure Fig.15: we’ve left the power supply for the Hummingbird somewhat open-ended, as it has pretty standard requirements. It just needs split DC rails without too much ripple, somewhere between ±20V and ±40V. The configuration shown here will produce around ±34V, which is right in the sweet spot and uses commonly available parts. Make sure your filter capacitors have a high enough voltage rating (above the highest expected peak DC voltage) and enough capacitance to ‘hold up’ the supply between 100Hz recharge pulses at the maximum sustained output power you’re expecting. Generally, you will need at least a few thousand microfarads per rail; ideally, at least 10,000μF per rail for multiple amplifier modules. siliconchip.com.au Australia’s electronics magazine and have low resistance; poor connections can easily double the distortion levels, or more. We found this measuring a batch of modules we built to verify our results; we had to tighten the connections to achieve consistent results. Getting the most out of it We expect this module to find use where a small, low distortion, rugged and reasonably-priced multi-channel amplifier is required. As these modules will fit on a 75mm heatsink, many of them can be mounted vertically in a 2U rack case. Our original application for this amplifier was to provide six channels for a stereo system using three-way loudspeakers with active crossovers. With two channels for subwoofers, two for mid-range two for tweeters, we expect the maximum continuous power to be 60W on each subwoofer channel, possibly half this for the mid and a tiny fraction of this on the high. As a result, a power supply based on a 300VA transformer will be more than enough for all six channels. Even a 160VA might cut it if you don’t plan on driving it especially hard. If your application calls for high power levels, there are more appropriate options, such as the SC200 and the Ultra-LD series. You could use a pair of those for the low-frequency channels and the Hummingbird for the others. SC December 2021  29 ► SMD Soldering Tips & Tricks While the only difference between SMD and through-hole components is how they are soldered to the PCB, there is a lot of jargon surrounding SMDs and new techniques required to work with them, especially the smaller types. This article accompanies our SMD Trainer project (starting on page 38) and provides a lot of detail to help you become an SMD soldering master. Image source: www.pxfuel.com/en/free-photo-qhfan By Tim Blythman U ndoubtedly, some people would prefer to learn how to solder SMDs by getting a hold of the Trainer board (see page 38) and some parts and just getting stuck into assembling it. However, soldering SMDs is a lot easier if you know the tricks. You might find the information in this article helpful even if you don’t plan on building the SMD Trainer. There’s plenty of general advice and hints here, so it’s well worth a read. However, keep in mind that this article is intended to accompany the Trainer; it does not describe less common components and SMD packages that do not appear on the Trainer PCB. If you have some SMD experience but still might have something to learn, you could read through this article and skip over any sections about subjects that you already understand. SMD component sizes and packages Many of the components used in our Trainer design (including the resistors, 30 Silicon Chip capacitors and diodes) have two leads (terminals) and are in so-called ‘chip’ style packaging. These are small, flat and roughly rectangular. These tend to be the most numerous type of components in any design based primarily on surface-mount parts. Some passive components come in different types of SMD packages. For example, it’s common to see small electrolytic can capacitors sitting on a small plastic base with SMD-style leads protruding. While smaller than most electros, they are still larger than most surface-mount passives, so they are not hard to work with. The parts in chip packaging are often described by a four to six-digit code, and there are both imperial and metric versions of this code. For example, a common 3216 metric sized part would be interchangeably known as 1206 under the imperial system. Confusingly, there are some parts with the same codes in both systems (including 1206), but they are very different sizes! Australia’s electronics magazine One way of differentiating these is to use the “M” prefix for metric sizes; this is what we prefer, and we will usually quote both to resolve ambiguity. For example, you will often see (M3216/1206) in our parts lists. This is the largest resistor and capacitor size that we have used in the SMD Trainer. Larger parts are available, though; the next step up is usually M3226/1210 and then M4532/1812. The first two digits determine the component length, while the other digits determine the width. Most parts are longer than they are wide, so the first two digits will be greater, but this is not always the case. Usually, the leads are along the short sides, but in cases where the leads span the longer sides, the numbers might be reversed (eg, M1632/0612). The metric digits are in tenths of a millimetre, so an M3216 part measures 3.2mm long by 1.6mm wide. Also note that the two terminals will be situated at opposite ends, lengthwise. Under the imperial system, each siliconchip.com.au pair of digits accounts for 1/100th of an inch, so a 1206 part is 0.12in by 0.06in, close to the metric equivalent. Table 1 summarises some of the more common two-lead sizes. Note the last row showing a five-digit imperial code (with a dimension under 1/100th of an inch or 0.25mm!). You can also see how, confusingly, some codes (such as 0603 and 0402) are present in both rows. On our Trainer board, the parts around IC1 are all M3216/1206 size. This is one of the largest sizes for which there is a comprehensive range of parts, so it is a good choice for using SMD parts where there is no need to go smaller. The LEDs around IC2 vary from M3216/1206 through M2012/0805, M1608/0603 and M1005/0402 down to M0603/0201. Each has a corresponding resistor of the same size. Another two-lead package that you might see is often used for diodes and is known as SOD-123 (small outline diode). These are similar in appearance to the transistor packages we’ll describe below, but only have two leads. Components with three or more leads IC1 and Q1 on our board are also in commonly-available SMD packages. For parts with more than two leads, there are often variants with differing pin counts but otherwise identical pin pitch and spacing between rows. Parts called SOIC or SOP (small outline IC or small outline package) typically have pins with 1.27mm or 0.05in pin pitch. This is exactly half the pitch of most DIL (dual in-line) through-hole parts. IC1 is in a SOIC-8 package with a 3.9mm body (plastic part) width. Like Table 1 – common passive SMD component sizes Metric M3216 M2012 Length 3.2mm 2.0mm Width 1.6mm 1.2mm Imperial 1206 0805 Length 0.12in Width 0.06in M1608 M1005 M0603 1.6mm 1.0mm 0.6mm 0.4mm 0.8mm 0.5mm 0.3mm 0.2mm 0603 0402 0201 01005 0.08in 0.06in 0.04in 0.02in 0.01in 0.05in 0.03in 0.02in 0.01in 0.005in DIL parts, width tends to increase as the pin count increases, to allow room for the internal leads to fan out along with larger silicon dies. The package we have chosen for transistor Q1 is called SOT-23 (“small outline transistor”). There are also variants with extra pins opposite each of these, called SOT-23-6, plus SOT23-5, which is much the same as SOT23-6 but lacking a middle pin on one side (see Fig.1 below). The basic SOT-23 parts (Mosfets, small-signal transistors, dual diodes etc) are quite easy to work with, as they will only fit their pads one way, and the pins are fairly well spaced and accessible. But they are getting to the point where their size means they are more likely to be misplaced, lost or simply fly into the distance without a trace if not handled carefully. A clean workspace of uniform colour is the best strategy against losing these tiny parts. The package size of IC2 on our Trainer board is the next step down, called SSOP for “small shrink outline package”. You’ll also see these with other modifiers, such as TSSOP (thin small shrink outline package). Either way, they’ll have a 0.65mm pin pitch, about half that of SOIC. Besides being thinner, TSSOP packages are also narrower than SSOP, so watch out – some M0402 footprints will suit either, but not all. Integrated circuit packages Another common IC package that is suited to hand-soldering is the QFP (quad flat pack) and its many variants, such as TQFP (thin quad flat pack). These come with a variety of pin pitches, with 0.8mm down to 0.4mm being typical. They are often used where more pins are needed in a small space, such as for microcontrollers. While the packages are not much smaller, with the pins arranged around four of the sides, they can be more tricky to align correctly. We’ve placed a QFP-44 (10x10) footprint on the rear of the PCB for reference; it has 44 pins (11 along each side), while 10x10 refers to the plastic case dimensions in millimetres. It has a pin pitch of 0.8mm. You can test your skills if you have a suitable part, although it won’t do anything. It could also be useful as a reference for checking dimensions and pin pitches. While it’s usually the tiny size of SMD parts that makes hand-soldering difficult, there are other reasons too. For parts smaller than SSOP, a designer might choose a QFN (quad flat no-lead), BGA (ball grid array), VTLA (very thin leadless array) or WLCSP (wafer level chip scale packaging). Fig.1: some of the more common surface-mount component footprints are shown at left (eg, SOT23, SOIC-8, SSOP-16, M3216/1206) along with pin numbering. siliconchip.com.au Australia’s electronics magazine December 2021  31 These parts are not intended to be soldered by hand, depending on a reflow process or similar to be soldered correctly. That’s not to say that they can’t be hand-soldered at all, but it is very difficult. Some parts can also have large ‘thermal’ pads on the underside of their packages that need to be soldered. Unless the PCB is designed with a via through the PCB to allow the solder to be fed from the other side, it isn’t practical to solder these by hand either (although a handheld hot air reflow tool can be used with great success). The packages and parts described so far are all standard to a degree. There are also numerous SMD parts that come in unique packages. Our SMD Trainer has two parts like this; the mini-USB socket and the coin cell holder. SMD component markings Markings on SMD parts can be cryptic, even when present, but resistors (above a certain size) are thankfully quite straightforward. Instead of a colour code, they are simply printed (or laser etched) with the numeric equivalent of the colour code. A through-hole 10kW resistor would have coloured stripes of brown, black, orange or brown, black, black, red, indicating 10 followed by three zeroes or 100 followed by two zeros. An SMD 10kW resistor would simply be marked ‘103’ or ‘1002’. Note that there is no tolerance code. Unfortunately, the common ceramic chip SMD capacitors are not usually marked at all. In this case, all you can do is make sure that the parts are well labelled in their packaging and only work with one value at a time. ICs can be tricky, too, as they usually have cryptic codes etched into the smaller space that’s available on their tops. SOIC parts may be large enough to have a sensible code, but SOT-23 parts are too small for this. Some manufacturers may even use the same code that another manufacturer has used for a different, incompatible part. The part’s data sheet usually indicates what code(s) they have used. ICs also have a mark indicating their orientation. Usually, the marking is intended to highlight pin 1. This may be a dimple in the plastic moulding or a bevel along one edge. Or it might be an etched symbol on the part top. Referring to the data sheet is the 32 Silicon Chip best way to find out what this mark will be. We usually mark the location of pin 1 on the PCB silkscreen with a small dot or “1”. Some SOIC parts will have a notch and bevel marked on the silkscreen too, corresponding to these features that might exist on the IC. Note, though, that different manufacturers of equivalent parts can use different methods for indicating pin 1. Since the smallest SMD components are not intended to be placed by hand, they generally have no distinct markings. Instead, a computerised pick and place machine is programmed to know how they are orientated in the tape reel on which they are supplied; the data sheet will often show this. As LEDs are polarised, they too usually have a polarity mark. It can vary, but it is usually a green dot or T-shape marking the cathode, or a small triangle that matches the direction of the triangle in the diode symbol and thus also points to the cathode. Tools & consumables This article is intended for relative beginners, so we will assume you mainly have tools intended for soldering through-hole parts. That means a soldering iron (temperature-controlled ideally) and some solder wire. You could use those tools to assemble the first section of our SMD Trainer Board with a bit of care, although a few extra items will be helpful. Tweezers You’ll need something to hold the parts in place while soldering. The small size means that you can’t use your fingers; even if they were small enough, they would get burnt very quickly! Fine-tipped tweezers are ideal. Kits like Jaycar’s TH1752 or Altronics’ T2374 are perfectly adequate, although precision points can be helpful for smaller parts. Just about anything that can be described as tweezers will be better than nothing. Flux Practically all electronics solder contains flux or resin, usually sufficient for through-hole construction. But you probably won’t realise the benefits that a separate flux can bring until you start using it. While you might be used to solder wire ‘just working’, it’s actually the resin core (the resin from certain trees makes an excellent flux) that is largely responsible for this. There are other, more modern and even synthetic fluxes, but resins (called “rosins” after purification) continue to be used as they are quite effective. If you’ve ever tried reusing solder, you’ll know that it doesn’t work as well as new solder. That isn’t due to its age, but because flux has been consumed. This is primarily due to the metal oxides that build up over time as metals react with oxygen in the air. One feature of flux is that it is a reducing agent; Tweezers are useful for holding components when soldering. You can also purchase tweezers with heating cores, which can be used for desoldering as shown in this photo. Source: https://commons.wikimedia.org/wiki/ File:Soldering_a_0805.jpg Australia’s electronics magazine siliconchip.com.au For applying flux there's a variety of different tools you can use, such as this flux pen above. We generally recommend using a flux gel syringe over a pen or container of paste because it's easy to apply and doesn't boil off immediately circuits but must be removed from mains circuits before applying power. The impurities captured by the flux can create a conductive path that would be dangerous at such voltages. You should also clean the flux off the PCB to be able to inspect it properly. Flux and slag can obscure solder bridges and poor solder joints. It’s best to clean as you go, rather than leave it all until the end, as flux is easier to remove when warm. Clean up using the appropriate chemicals. It’s best to use Nylon brushes and/or lint-free cloths since you don’t want to leave fibres behind on the board. Don’t just spray or pour the cleaning solution onto the board; you need to remove it after it has had a chance to dissolve the flux. Sometimes letting it sluice off will carry away much of the flux, but you’ll still need to dab it dry. You may find that the cleaning process is imperfect or, even worse, reveals a soldering failure. There’s no choice but to go back and fix the problem, then clean and inspect it again. the simple explanation of this property is that it can reverse oxidation. The flux reacts with the oxides to leave a pure metal that will bond better. Many fluxes also form a layer to keep out oxygen and prevent further oxidation, which also applies to the solder itself, PCB pads and component leads. Another feature of flux is that it should be heat-activated and only work near the soldering temperature. This prevents it from being used up prematurely. Flux can also enhance heat transfer. Since all surfaces need to be heated above the solder melting (eutectic) point to enable good solder bonding, flux can help get heat into where it is required. The flux can be applied directly to the parts and PCB in surface-mount work, facilitating heat transfer from the iron to all components. The flux also reacts with the various oxides and contaminants to neutralise their negative effect on the soldering process. The reaction products are referred to as slag. This is due to the reactions with the various oxides. The result is often a dark, sticky substance that collects on the tip of the soldering iron. Flux can also be a potently corrosive chemical and can damage a board if any is left behind. Your flux should have a data sheet that explains this aspect in detail; those marketed as ‘no-clean’ are less likely to leave a corrosive residue. Liquid fluxes, flux pens and flux pastes are available; our preference is for a paste or gel as it is easier to apply and control and sticks around longer. Even for the amount of soldering we do, a fairly small syringe lasts for years (or at least until it expires), so there is no need to buy a huge amount of flux paste. For ease of handling, we recommend getting a small syringe, such as Altronics’ H1650A Flux Gel Syringe. The syringe allows for the precise application of small amounts. soldering, especially if you use a lot of flux (which is not a bad idea since it results in more reliable joints). You’ll probably find that you’ll need to clean your iron’s tip as you go. A cleaning sponge is the most common choice here; lightly moisten it, just enough to prevent the iron from burning the sponge. We’ve seen brass sponges that work pretty well, but they don’t seem to have the ability to capture all the residue. In a pinch, a lightly-moistened paper towel works well. Cleaning A solder sucker is better for removing a larger volume of solder, while a braid is better for smaller jobs such as SMD components. Source: https://commons. wikimedia.org/wiki/File:Solder_sucker.jpg It’s important to clean up after siliconchip.com.au Solvents Most fluxes will also recommend a cleaner (even the so-called no-clean fluxes). Isopropyl alcohol (isopropanol) is a reasonable all-around choice. Some fluxes and their slags are sticky and might require scrubbing to be cleaned up properly. Therefore, an even better option is a specialised flux cleaner like Chemtools’ Kleanium Deflux-It G2 Flux Remover (siliconchip.com.au/link/ abad). Take care with these solvents. Many, including isopropyl alcohol, are flammable, while some are poisonous or can damage the skin. The solvent datasheet or MSDS is the best place to find advice and information about these things. The presence of flux should not inhibit testing of most low-voltage Solder wicking braid You might also hear this called desoldering braid or solder wick; it is a length of finely woven copper wire that has usually been impregnated with some sort of flux. It is used to wick away (or absorb) excess solder. A typical use is removing the excess solder which has formed a bridge between two pins, or cleaning solder from a pad after removing a defective part and before fitting a new part. It is pretty cheap; you can purchase a small roll over 1m long for a few dollars from Jaycar (Cat NS3020) This is a close-up of some solder wick braid. It's normally sold on a reel and is used for cleaning solder. Source: https://commons.wikimedia.org/wiki/ File:Solder_wick_close_up.jpg Australia’s electronics magazine December 2021  33 You might need to use the zoom feature (even digital zoom will be very helpful) to see a reasonable amount of detail. If your device has a macro mode, then that will be better suited for close-up viewing too. But we generally find that it’s handy to have a fixed magnifier that can be rigged up in place above a PCB, as well as a small handheld unit that can be picked up and aimed as needed. Lighting While it doesn't need to be an all-in-one package, a magnifying glass, PCB holder and good lighting will help to make soldering small components easier. This is the Jaycar TH1987 mentioned below. or Altronics (Cat T1206A). A typical use might consume a few millimetres of braid, so it too will last for quite a while. PCB Holder Many boards that use SMDs are quite small, and it can be helpful to secure a PCB in place while working on it. It’s also handy to be able to move it around to access a particular component at a certain angle. Tool’s like Jaycar’s TH1982 Third Hand PCB Holder or Altronics’ T2356 Spring Loaded PCB Holder are ideal. The PCB is held in place but can be adjusted, or the entire tool rotated, to allow access from different angles. While these tools are not expensive, even something like Blu-Tack or a similar reusable putty can be a handy makeshift substitute. While the heat from the iron will likely soften and tarnish the Blu-Tack, we’ve never had any trouble using it to hold a PCB in place. Magnifiers Being able to clearly see the tiny parts and features involved with SMD projects is paramount. There are two important ways that you can improve the way you see: magnification and illumination. If you have keen eyes and you’re working with some of the larger parts in SOIC and M3216/1206 packages, you may well do fine without magnification. But it is still vital to peer closer 34 Silicon Chip to inspect your work and check that everything is as it should be. Fortunately, there is a vast range of things that you can use for magnification, and you might well already have some of these, like a simple handheld magnifying glass. Some PCB holders include a magnifier of some sort, including Jaycar’s TH1987 PCB Holder with LED Magnifier. That one includes a soldering iron stand too. The other extreme is a microscope. While certainly not as cheap, not much magnification is needed. Many microscopes also provide excellent illumination. These days, there are many USB and digital microscopes available. A smartphone camera is a suitable piece of gear that most people will already have in their pocket. A digital camera with an LCD viewfinder is a similar option. Good lighting is paramount for successful SMD work. A diffused light source is best, as point sources can cause shadows that obscure parts of the PCB, especially between component leads where bridges might form. If you only have point sources, then aim them from opposite sides to cancel shadows. You can diffuse the light by reflecting it off something white like a wall, ceiling or sheet of paper. As long as you’re happy you can see what you need to see, then you probably have enough light. Fume extractions Remember that flux also generates smoke which is unhealthy to inhale. A fume extraction hood is the recommended way of dealing with this but can be expensive. A small fan (such as a computer fan) can work too, set up to blow away from you. If you can’t manage some sort of active fume control, working outside (or near a large open window) is another option. Top gear If you don’t already have them, the items we’ve mentioned so far are all available at reasonably low prices. We’ll also briefly touch on a few items that can further enhance your SMD experience. Some form of fume extraction is important if you're working in an enclosed area. While this Hakko FA430 (August 2011; siliconchip.com.au/Article/1121 siliconchip.com.au/Article/1121) may be out of the budget of some hobbyists, you can instead just use a small fan to blow the fumes away. Australia’s electronics magazine siliconchip.com.au As we noted earlier, a basic soldering iron is probably adequate to work with larger SMD parts. When you start to get into the smaller parts, then some optional features become essential. Two aspects will help. A fine tip will allow more accurate soldering as you generally want to make contact with just one pin at a time (but see the section below about drag soldering; larger tips can be better with those techniques). The edge of a chisel tip can be narrow enough to work down to relatively small sizes. A soldering station with adjustable temperature is an advantage when working on larger parts. Many of these come with stands and sponges, which also help. Finally, a hot air rework gun can be very handy for desoldering SMDs or reflow-soldering some of the trickier parts. These are available at surprisingly low prices and are well worth having if you plan to do much work with surface-mount components. Using your tools To sum up the advice given above, make sure you have some flux paste, a soldering iron tip-cleaning sponge and some appropriate solvent for your chosen flux. Use the flux generously and keep your iron’s tip clean. Soldering techniques If you’ve read any of our SMD construction articles before, then the following will be familiar. We’ll even go into quite some detail about how you use the tools we’ve just mentioned. You can also follow along with the photos we’ve included. Apply flux to the pads of the components in question. It is a good idea to work in small groups of similar components. For example, you might plan to work with all the 10kW resistors if there are many of them. If there are a small number of different values, then they can be worked in parallel. One exception to this are capacitors, which, as we noted earlier, do not usually have any distinguishing markings. In that case, we recommend sticking to a single value at a time. Roughly place the components on their pads. Flux gel or paste will generally be sticky enough to hold them in place. You might find that your tweezers pick up small amounts of flux and will then stick to components. That’s another reason to keep everything quite clean. Adjust the component with the tweezers so that it is centred on its pads. The amount of PCB pad visible will dictate how easy it is to apply the soldering iron, so symmetrical placement is not just neat, but crucial to ease of soldering. For tiny leads, it can help to apply some flux to the top of the lead too. Clean the iron’s tip and apply a minuscule amount of fresh solder to it. Gently hold the component down flat against the PCB with the tweezers and touch the iron to both the pad and lead together. Hold it there for a second to allow the parts to heat up and bond with the solder. You should see the solder flow from the iron and onto the part and pad. Remove the iron and continue to hold the part in place while the solder solidifies. One second will be sufficient for small parts with fine leads, perhaps longer for larger components. If the part has moved or is not flat against the PCB, grip it with tweezers and apply heat to melt the solder. Adjust its position until you are happy. If the part looks like it is still wellaligned and flat against the PCB, apply some fresh solder to the iron and work through the remaining pads. Medium conical tips are used for general soldering including through-hole and larger SMD components. They have the advantage of being usable at virtually any angle. Finer conical tips are able to make contact with smaller leads, so they are more suitable for soldering large-to-medium SMDs, while still working with smaller through-hole parts. The wide contact area of chisel tips makes them handy for applying solder wick to remove solder, as well as heating SMD tabs or reflowing the pins on one side of a device. Like the chisel, the knife tip can make contact with a large area of the board at one time. Its angle makes it more comfortable for running down the sides of ICs. Bevel tips can contact an even larger area but the larger tips like this one are generally too large to get near smaller components. Smaller bevel tips are not only more manoeuverable but you can also angle them to make contact on just one edge, or the whole face when needed. An SMD flow tip is similar to a bevel tip but it has a depression in which to hold molten solder. This makes them ideal for drag soldering many pins at once. siliconchip.com.au Australia’s electronics magazine December 2021  35 Metric 0402 0603 1005 1608 2012 2520 3216 3225 4516 4532 5025 6332 1 x 1mm Imperial 01005 0201 0402 0603 0805 1008 1206 1210 1806 1812 2010 2512 0.1 x 0.1in 1 x 1cm This diagram shows common SMD component sizes at actual size. The metric 0402 component is so small that it is barely visible! An example of wave soldering showing the PCB leaving the heater portion of the machine and being moved to the solder wave. Source: https://youtu.be/ VWH58QrprVc For very narrow or fine pads, place the iron onto the pads first. The solder mask on the PCB will help to prevent the solder from flowing where it shouldn’t. We try to enlarge the pads in many of our SMD projects to make this easier, although you won’t find this in all designs. Depending on the iron, pad and flux, the solder may be drawn onto the pad and lead by surface tension alone. The advantage of this is that the iron does not obscure the view of the lead so that you can observe the joint forming. The behaviour of solder and its surface tension at the small scales used for SMDs is critical, so this will help you get a feel for what works. You might have seen parts being soldered with solder paste in a reflow oven; when the solder liquefies, the part snaps into the correct location. This is due to the surface tension, pad location and the importance of the solder mask. Surface tension also pulls solder exactly where it is needed. Only a tiny amount of solder is required if the parts are flat against the PCB. If you see clean, curved fillets of solder, that is a good indication that the joint is well-formed. You can use surface tension to apply a generous amount of solder to ensure a strong joint. A bulging but clean and glossy joint is sure to be more functional and solid than a tiny fillet that cannot be seen, just as long as it doesn’t bridge out against any other part! These movements are what has to be practised. The timing will also depend on things like your iron temperature and choice of (tin-lead or lead-free) solder. If you experience a solder bridge, and as long as the part is correctly aligned, continue to solder the remaining leads. Then sort out the bridge. Use the technique described earlier to remove solder from bridged leads. Apply more solder if needed (especially if you can’t easily access the bridge). Apply flux, braid (see below) and then the iron. Allow the braid to absorb some solder, then carefully slide both away. Inspect the part closely with a magnifier. If the joint appears dry or unclean, then apply fresh flux and gently touch the clean iron tip against each lead in turn. You’ll find that even this step of refreshing each lead will help distribute solder to where it should be. Drag soldering When SMD components have pins that are very close together, it becomes impractical to solder them individually. The only component on the SMD Trainer PCB that we would consider having such tight pin spacings is IC2, in an SSOP package with 0.65mm pin pitch. Some chips have an even finer pitch, down to about 0.4mm (eg, TQFP-144). In these cases, it’s easier to drag solder the ICs. Once the chip has been tacked in place and flux has been applied to the pins, a small amount of solder is loaded into the iron’s tip and then gently dragged along a row of pins. Surface tension pulls a small amount of solder from the tip and onto the pins. Done correctly, it forms When drag soldering you'll typically use a flow or bevel tip. The easiest way to learn hown to drag solder would be by watching a video, such as the many found on YouTube. Source: https://youtu.be/ nyele3CIs-U Some common soldering iron tips; most are suitable for SMD work. 36 Silicon Chip Australia’s electronics magazine siliconchip.com.au Table 2 – common types of solder Type of Solder Composition/Name Melting-point Comment Lead-based SnPb 60/40% 188°C Higher tin (Sn) concentrations lead to greater strength SnPb 63/37% 183°C Eutectic – melts/solidifies at a single temperature Sn100C 227°C Silver-free; contains copper, nickel and germanium SAC305 217-220°C Contains tin, silver and copper; used in wave soldering SnCu 217-232°C Contains tin and copper; tin-based lead-free solders are quite often used for reflow and wave soldering SAC387 217-219°C Contains tin, silver and copper Rosin NA Helps to facilitate soldering Non-rosin NA Often contains metal halides such as zinc chloride, hydrochloric acid, citric acid etc; can be corrosive Silver, copper, brass, bronze etc >450°C Often used for jewelry and are designed to have a melting point just below that of the corresponding metal Lead-free Flux Hard solder perfect joints the first time. It’s generally better to apply too much solder than not enough as bridges are easier to see than joints with insufficient solder, and they are easily cleaned up using braid (see below) and more flux. You can get special flow soldering iron tips with ‘wells’ (depressions) to hold the solder for this technique, but you can get away with a standard tip. You just have to add more solder to it more often (eg, every 5-10 pins soldered instead of every 30-40 pins). Even larger-pitch ICs like the SOIC types can be soldered using this sort of technique; it can be quicker (and neater) than soldering them individually. Using braid Solder braid is best for removing small amounts of solder, while a solder sucker is better for removing large volumes. So if you have a lot of solder to remove, start with the sucker to remove the bulk and finish with the braid to tidy up. But at the tiny scales involved with SMD parts, solder suckers become unwieldy and likely to simply inhale your parts as well as the solder you’re trying to remove. The amounts of solder you need to remove will be pretty small too. Before using the braid, it helps to add flux. The word “flux” comes from the Latin word “fluere”, meaning to flow; we want to encourage the solder to flow into the braid. Press a clean part of the braid onto the solder with your iron and allow everything to heat up enough to melt the solder; it should start to soak into the braid. Being made of copper, the braid conducts heat well, so place your grip with care or use tweezers. After the braid takes up the solder, carefully move both the iron and braid away together by sliding away across the PCB. You don’t want to remove the iron first and have the braid soldered to your PCB! It can sometimes help to add more solder where you want to remove it, especially if it’s a solder bridge tucked deep between two pins. The extra volume can give the braid more surface to contact. If there is a dark residue on your PCB after using braid, this is probably the byproduct of the flux working. For areas like this, a cotton-tipped swab dipped in flux cleaning solvent can be used to clean small regions before SC continuing. The basic principles of wave soldering. The PCB is carried ► along over the solder bath by a conveyor. At one point, the solder is forced up in a “wave” so that the bottom of the board passes through it. The components and copper tracks are soldered and the board then emerges from the bath. ► siliconchip.com.au Australia’s electronics magazine Reflow soldering doesn’t use a soldering iron at all – temperaturecontrolled hot air or IR is used to melt the solder “paste” applied to the component and copper tracks to be soldered. The board passes through the oven, the solder paste melts and hey presto – a soldered joint. December 2021  37 By Tim Blythman SMD Trainer Board Are you interested in learning to solder small surface-mount devices but don’t want to ruin an expensive board or chip gaining those skills? Perhaps you have no choice but to learn since so many parts made these days only come in SMD packages. This simple Trainer project is a great way to practice soldering a variety of surface-mount devices. If done correctly, you’ll be rewarded with a series of LEDs flashing in sequence. S urface-mount devices (SMDs) are the preferred type of parts used in most commercial equipment to their compactness, good reliability, low cost and widespread availability. While some manufacturers are still producing new through-hole parts, your choices become a lot more limited if you can't handle SMDs. We know it seems daunting initially (it did to us, too), but you will be surprised how easily you can do it with a bit of practice. And that's precisely what this board is designed for. It's a working circuit designed using a wide variety of different SMD parts, allowing you to try out soldering them. This way, you can master the techniques and become familiar with the common sizes and packages. It's designed so you can start with the larger parts and, as you gain confidence, move onto the smaller ones. And you can test it along the way, so you'll find out pretty quickly if you've made a mistake and have an opportunity to correct it. This article includes the basic instructions for building and testing the Trainer board, along with a description of how it works. The 38 Silicon Chip accompanying article, starting on page 30, provides considerably more detail regarding the necessary tools and techniques. We recommend that you look at that article now and refer back to it later if you come across anything that you don't fully understand. That's especially the case if you are not experienced at soldering, or have doubts about your ability to handle SMDs. Assuming you have read that article (at least in part) and are starting to get an idea of how you would go about assembling this board, let's move on to describing its design. Common to both parts is the power supply. Coin cell holder BAT1 is paralleled with a USB socket, CON1. Only one of these should be fitted. We recommend the coin cell holder, as a coin cell is less likely to deliver damaging current in case you make a mistake building it. Because of the presence of a coin cell, take care that the SMD Trainer is kept out of reach of children. It has flashing lights, so it will appeal to curious eyes, but there is no reason for it to come into a child's hands as it is not a toy. Circuit details IC1 is a timer IC (a 7555). We've chosen this CMOS variant rather than the bipolar transistor based 555 to allow the circuit to work at low voltages and be powered by a coin cell. The supply passes to IC1's pin 8 (positive) and 1 (negative). Pin 4 (RESET) is held high to allow the timer to run. IC1 has its supply bypassed by a 100nF capacitor and a second 100nF capacitor stabilises the internal voltage on the CV pin, pin 5. IC1 is configured with the 100kW resistors and 1μF capacitor in the well-known astable The circuit of the SMD trainer board is shown in Fig.1. We'll explain how it works before going any further. It's important to know what it should do, especially so that you can figure out what's wrong if it doesn't work initially. There are two main parts to the circuit, the second of which depends on the first. The first part of the circuit is also easier to build, so you can try out your skills on that before dialling up the difficulty. Australia’s electronics magazine First half siliconchip.com.au Fig.1: this simple circuit lets your soldering efforts speak for themselves. IC1 is configured as an oscillator that alternately flashes LED11 and LED 12. IC2 is clocked from IC1's output and lights up each of LED1-LED10 in turn. Power comes from either a USB socket or coin cell holder. oscillator configuration. In this arrangement, the 1μF capacitor charges from the supply via the two 100kW resistors; its top is connected to input pins 2 and 6. When pin 2 rises above 66% of the supply voltage (about 2V), an internal flip-flop toggles and pin 7 is connected to ground (through a transistor inside IC1). At the same time, pin 3 goes low. This causes the 1μF capacitor to discharge through the lower 100kW resistor into pin 7, until the voltage on the capacitor reaches 33% of the supply (about 1V). The flip-flop resets, pin 3 goes high, pin 7 stops sinking current, the capacitor begins charging again, and the cycle repeats. With the provided component values, the oscillator frequency is around 4.8Hz with a 66% duty cycle at pin 3 (ie, pin 3 is high about 2/3 of the time). When pin 3 is low, current is sunk from the supply via LED12 and its 1kW series current-limiting resistor, causing it to light. When pin 3 is high, Mosfet Q1 is switched on by the positive voltage at its gate, and current flows through LED11 and its series resistor instead. Thus these two LEDs flash alternately. This first part of the circuit is built from larger SMD parts, like those we usually include in our projects when through-hole parts are unsuitable. It can operate independently of the siliconchip.com.au remainder of the circuit, and can be built and tested as the first part of a two-part challenge. Second half A horizontal line on the PCB divides it neatly into two distinct parts; part two is below this line. IC2, a 4017-type decade counter, is the heart of the second part of the circuit. It is powered from the same supply as IC1, connected to its pin 16 (positive supply) and pin 8 (negative supply). Its supply is also bypassed by a 100nF capacitor for stability. IC2 has ten outputs at pins 3, 2, 4, 7, 10, 1, 5, 6, 9 and 11. These are driven high, one at a time, in response to a clock signal applied to pin 14. This signal comes from pin 3 of IC1 mentioned above. Pins 13 and 15 are pulled low to allow normal counting operation. Pin 12 is a carry output, which can be cascaded to other chips, but is left disconnected in this case. Each of the ten outputs noted above has a 1kW series resistor and LED connected to its output. Thus, a clock This is the SMD Trainer board that we put together (shown at approximately 166% actual size). If you're having trouble making out the M0603/0201 LEDs, it might be because they're not fitted! We couldn't solder these by hand, and won't pretend that it's easy to do so. Australia’s electronics magazine December 2021  39 intended to be hand-soldered), the ICs typically have finer leads and are harder to work with. So it makes sense to do them first and then work on their surrounding passive components, which are often larger. Assembling the SMD Trainer The SMD Trainer is designed to function without all components installed, making testing your SMD work easy. signal at pin 14 causes the LEDs to light up in order, one at a time. The components around IC2 have a variety of sizes to present a more interesting challenge; IC2 is also in a smaller SMD package than IC1. See Table 1 for more details. Placement and order Our recommended assembly order for most through-hole designs is for a few reasons. Working by component type, for example, starting with resistors, then diodes, capacitors and then ICs, makes it easier to keep track of what step you are up to. For the most part, this order is dictated by the component heights. Components that are close to the PCB are placed first as they don't restrict the placement of taller parts. Also, this means that the PCB can be turned upside down without the throughhole components falling out; they are held on the PCB by the work surface. Working with SMD parts has similar motivations, but there is much less need to invert the PCB, so no real chance of parts falling out. Also, most SMD parts have a low profile. So the primary consideration will be to place the more difficult-toaccess or difficult-to-solder parts first, so that they aren't impeded by parts fitted later. With this in mind, the best way to construct hybrid circuits (that have both through-hole and SMD parts) is to fit the SMD parts first. Whether they are on the same side or not, the taller through-hole parts will be a greater impediment to construction if they are fitted before the smaller SMD parts. This also means that the process of placing ICs last is no longer appropriate. Nowadays, ICs tend to be more rugged and less prone to damage from static, which was usually the motivation to fit them as late as possible. In SMD designs (or at least those Refer now to the PCB overlay diagrams, Figs.2 & 3, which show which components go where. The SMD Trainer PCB is double-sided, measures 70.5 x 40mm and is coded 29106211. We recommend starting with the USB socket if you will be fitting it. The leads are not too small, but they are not very accessible. Fortunately, this part has locking pins on the underside that go into holes in the PCB. So positioning the part correctly is easy. Place flux on all the pads for the USB socket and press the part down. For this application, only the two outer pads of the five are needed to supply power; hence they are the only ones that are extended. You can add more flux to the top of the pads too. Clean the iron's tip, apply a small amount of solder and press the iron against the PCB pad. If the solder doesn't run onto the lead, bring it closer, until it is touching if necessary. Repeat for the other outer pad. With this connector, make sure you don't touch the iron against the USB socket shell when making these power connections. The tight angle here is what makes this tricky. If you form a bridge, apply heat to all the pins to remove the part and tidy both the socket and PCB with solder braid. For the larger pads that secure the USB socket mechanically, simply apply the iron, add some solder until a tidy fillet forms, then remove the iron. Figs.2 & 3: start by fitting the components in the top half of the PCB, which forms the alternate flasher, lighting LED11 & LED12. These components are larger SMDs that are generally not too hard to solder. Once you have those working, you can move onto the more challenging parts below, which form an LED chaser. With IC2 and its bypass capacitor in place, fit LED1, LED6 and their series resistors, then move onto the smaller parts, testing it at each step to ensure your soldering is good. 40 Silicon Chip Australia’s electronics magazine siliconchip.com.au A generous amount of solder here will result in a secure connection. Using a similar procedure, place IC1 and Q1, ensuring that they are rotated correctly. Then solder the resistors and capacitors in place. Note that there are two different values of each; you can refer to our photos too. The LEDs are polarised too, and must be fitted with their cathodes to the left towards the resistors. If you wish to fit the cell holder instead of the USB socket, do so now. It's usually easier to fit parts on one side of the board at a time, but this will allow you to test out the first part of the circuit that you have just assembled. Flip the PCB over and put some flux on the two smaller outer pads. Leave the large inner pad clear, as the PCB pad itself becomes the negative terminal and doesn't need soldering. Also ensure that the holder opening is towards the edge of the PCB, so that you can easily insert the cell. Position the holder roughly in place and add some flux to the top of the leads too. Note that, unlike the USB socket, there is nothing to lock this part in place. You will probably need to turn up the temperature on the iron slightly (if it's adjustable) and load some solder onto the tip; a bit more than for the smaller parts. Use tweezers to keep the cell holder in place and touch the iron to the pad. Give it some time to heat up; remembering that it is all one piece of metal, so it is unlikely to be damaged by too much heat. You should see the flux smoke and the solder flow. Remove the iron and give the part (and solder) a few seconds to cool before releasing the tweezers. Parts List – SMD Trainer 1 double-sided PCB coded 29106211, 71 x 40mm 1 mini-USB socket (CON1) OR 1 SMD coin cell holder (BAT1) [BAT-HLD-001; Digi-Key, Mouser etc] Semiconductors 1 7555 CMOS timer IC, SOIC-8 (IC1) 1 4017B decade counter IC, SSOP-16 (IC2) 1 2N7002 N-channel Mosfet, SOT-23 (Q1) 4 M3216/1206 size LEDs, any colour (LED1, LED6, LED11, LED12) 2 M2012/0805 size LEDs, any colour (LED2, LED7) 2 M1608/0603 size LEDs, any colour (LED3, LED8) 2 M1005/0402 size LEDs, any colour (LED4, LED9) 2 M0603/0201 size LEDs, any colour (LED5, LED10) Capacitors (all SMD X7R 10V+ ceramic) 1 1μF M3216/1206 size 3 100nF M3216/1206 size Resistors (all SMD 1% or 5%) 2 100kW M3216/1206 size Altronics kit will be available 4 1kW M3216/1206 size 2 1kW M2012/0805 size Altronics has announced that they will be 2 1kW M1608/0603 size making a kit for this project, code K2001. 2 1kW M1005/0402 size 2 1kW M0603/0201 size The first joint doesn't need to be perfect; the main thing is that the part is accurately placed and held firmly. The second pad can be approached like the larger pads on the USB socket. Apply the iron, feed in the solder until a good fillet is formed, then remove the iron. Give it a few seconds to solidify before returning to the first pad to make it tidy. You can touch it up by applying the iron and solder in the same fashion. Initial testing The first part of the circuit should now be functional. You can test it by fitting the button cell or applying power from a USB source. If using the button cell, make sure the polarity is correct. You should see LED11 and LED12 flicker alternately. If one LED is stuck on, then IC1 is not oscillating, and you should check it and the components around it. If only one LED is flashing, the other might not be soldered correctly; this could include either of the 1kW resistors or Q1. You might also see what appears to be the two LEDs on at the same time. In that case, they are probably flashing faster than the eye can see. One possible reason for this is that the 1μF timing capacitor has been mixed up with one of the 100nF capacitors. At this point, it's best to verify that this part of the circuit works correctly. Otherwise, if the second part doesn't work, it will be harder to determine the problem. Remainder of the circuit There's a set of TQFP pads located on the underside of the PCB. This is for you to practice soldering, and does not have any electrical connection to the circuit. siliconchip.com.au Australia’s electronics magazine You'll note that the components in the lower half of the PCB are fairly well spread out. This is a luxury that won't be present in all SMD designs. With the amount of space present on the SMD Trainer, it's certainly possible to install these components in just about any order. But we recommend starting with IC2 and its capacitor, followed by the LEDs in order of size from largest to smallest. This will allow you to power up the circuit at any time after December 2021  41 Table 1 – common passive SMD component sizes Metric M3216 M2012 M1608 M1005 M0603 M0402 Length 3.2mm 2.0mm 1.6mm 1.0mm 0.6mm 0.4mm Width 1.6mm 1.2mm 0.8mm 0.5mm 0.3mm 0.2mm Imperial 1206 0805 0603 0402 0201 01005 Length 0.12in 0.08in 0.06in 0.04in 0.02in 0.01in Width 0.06in 0.05in 0.03in 0.02in 0.01in 0.005in you have any of the larger LEDs fitted, and check that it is working. Start with IC2. Apply flux and position the part. We've been quite generous with the length of the pads here, for two reasons. Firstly, we have seen SOP variants of this part being available with various body widths. So this pad configuration offers the flexibility to accept a range of compatible parts. Secondly, it makes it easier to solder. Clean the tip of the iron and add a tiny amount of fresh solder to it. Hold IC2 with the tweezers and apply the iron to the PCB pad only. You should see the solder flow onto the lead and form a joint strong enough to hold the part in place. Check that the leads are aligned and solder the remaining pins in this fashion. These tiny parts do not need much solder, so you might find that you only need to occasionally add solder to your iron. Check for bridges and rectify as needed. Follow with the remaining 100nF capacitor. LED1 and LED6 are M3216/1206 sized parts, so you should be comfortable fitting them and their respective 1kW resistors. Note that all cathodes are on the side away from IC2. And test again Our design is incrementally functional, so you can power and test the partially completed design at just about any time. You should see LED11 and LED12 continue to alternate as before; if they do not, then you might have a short circuit that is shunting power away from IC1 and its components. LED1 through to LED10 should flicker on and off in turn when fitted. If you get nothing at all, check that IC2 is fitted correctly, with the correct orientation and no bridges. Individual LEDs not flashing are probably a sign that a single LED or its resistor are not fully soldered. Completion Take your time and work through the differently-sized LEDs and resistors in turn. Don't be disappointed if you can't solder the M1005/0402 or M0603/0201 parts by hand. We have not used anything smaller than M1608/0603 in any of our designs, and even we find anything smaller than M1005 challenging. The last time we used components as small as M1608 was for the DAB+ Touchscreen Radio (January-March 2019; siliconchip.com.au/Series/330). Even then, we offered the PCBs with these smaller parts pre-fitted. Anything that tiny is not intended to be soldered by hand. The smaller LEDs often have exposed pads only on the underside, making it very difficult to transfer heat where it is needed. There are some tricks you can use, such as applying a small amount of solder to the pads and trying to conduct heat through the PCB trace radiating out from the lead. Or try your hand at reflowing solder using hot air or infrared. We published a DIY Solder Reflow Oven design in the April and May 2020 issues (siliconchip.com.au/ Series/343). It is also possible to successfully reflow a board with 'tools' such as electric frypans and clothes irons! Cleaning Once you are satisfied with your progress, clean up any residual flux and allow the board to dry fully. Although the board doesn't do anything incredibly useful, it is still a handy reference tool and will remind you of the tricks and techniques you learned in its construction. Complete Kit While stocks last, we will be selling a complete kit of parts (siliconchip. com.au/Shop/20/5260) or get one from SC Altronics. Further reading We have, of course, written articles in the past about surface mount technology, devices and construction. They are as follows: ● Make Your Own SMD Tools, Circuit Notebook July 2007 (siliconchip.com.au/Article/2289) ● How To Hand-Solder Very Small SMD ICs October 2009 (siliconchip.com.au/Article/1590) ● Soldering SMDs: it’s becoming unavoidable December 2010 (siliconchip.com.au/Article/376) ● Simple DIY gizmos for SMD desoldering, Circuit Notebook July 2014 (siliconchip.com.au/Article/7944) ● Publisher’s Letter: SMDs present challenges and opportunities September 2015 (siliconchip.com.au/Article/8955) ● Third hand for soldering tiny surface mount devices, Circuit Notebook April 2016 (siliconchip.com.au/Article/9901) ● Publisher’s Letter: It’s getting hard to avoid tiny SMDs January 2019 (siliconchip.com.au/Article/11361) ● A DIY Reflow Oven Controller for modern soldering April & May 2020 (siliconchip.com.au/Series/343) 42 Silicon Chip Australia’s electronics magazine This M0603-sized component, shown on a fingertip, measures a miniscule 0.6 x 0.3mm, making it easy to lose. siliconchip.com.au Using Cheap Asian Electronic Modules By Jim Rowe Geekcreit’s 35MHz4.4GHz Signal Generator This self-contained module is based on the Analog Devices ADF4351 wideband digital synthesiser chip. It has an onboard microcontroller unit (MCU), OLED display and pushbuttons to set the desired frequency and adjust the output level. All it needs is a 5V DC power supply. If the ADF4351 sounds familiar, that’s because it was also used in the digitally-controlled oscillator we reviewed (May 2018; siliconchip.com. au/Article/11073). But whereas the earlier unit needed to be controlled via a separate microcontroller such as an Arduino or a Micromite, this one is a self-contained instrument, delivered ready to use. It is larger than the earlier one, measuring 88 x 67mm compared to 48 x 36.5mm. But the price isn’t all that much higher, currently setting you back $48 plus $7 for shipping to Australia. It can be purchased from Banggood (siliconchip.com.au/link/ab83). As shown in the photos, it comes with two cables: a USB Type-A to mini-B cable and a 240mm-long DC cable with a plug on one end to match the module’s DC input socket. It also comes fitted with four 5mm-long Nylon mounting spacers and matching screws. But no case is supplied, so you’ll either need to use it as a ‘bare’ module, or come up with your own arrangement. On the PCB, there’s an STM32F103 MCU (visible at lower left), a small siliconchip.com.au OLED (organic light-emitting diode) display with a 128 x 64 pixel 25mm (1-inch) diagonal screen, and a total of seven pushbutton switches. The five at lower right control the module, while the one in the centre resets the MCU. The one near the upper left with a square body and blue actuator is the ON/OFF switch. The ADF4351 synthesiser chip and its surrounding components are all in the upper right-hand corner of the PCB. The two nearby edge-mounted SMA sockets are the RF outputs, while the vertical SMA socket near the centre of the PCB is an input for an optional external master clock, an alternative to the onboard 100MHz crystal oscillator. The ADF4351 chip at the heart of the module is a digital ‘phase-locked loop’ or PLL device, and a pretty fancy one at that. But there isn’t space here to give you a full explanation of PLLs and how the ADF4351 itself works. So if you want to know more about these aspects, refer to the May 2018 article A close-up of the 1-inch OLED screen when using the “Point” command from the main screen. Australia’s electronics magazine December 2021  43 (siliconchip.com.au/Article/11073), which has a comprehensive explanation. The data sheet for the ADF4351 can be found at siliconchip.com.au/ link/aajc UG-435, which you can download from their website (siliconchip.com. au/link/ab82). A brief rundown Lack of instructions How it works The ADF4351 is a wideband digital synthesiser IC with a ‘fractional-N’ PLL, allowing it to be programmed to produce any desired output frequency between 35MHz and 4.4GHz. It is locked to a ‘master clock’ crystal oscillator of typically 25MHz or 100MHz. It can be programmed to change the output frequency in steps as small as 10kHz, and can also provide an output sweeping over a range of frequencies in steps of the same minimum size. The whole chip is controlled/programmed via a simple three-wire serial peripheral interface (SPI), in this case, via the onboard STM32F103 MCU. The Geekcreit 35-4400MHz signal generator module comes with very little user information, so you have to work a lot out for yourself. All you get is a brief summary of its main specs and features, and you can download a circuit diagram that is not easy to decipher. So before I began testing the module, I spent a couple of hours redrawing the circuit so that we can all see how it works, shown in Fig.1. Like the earlier module, this one is fairly closely based on Analog Devices’ evaluation board for the ADF4351. That is described in their User Guide In Fig.1, the ADF4351 (IC2) is on the right, with its onboard 100MHz master clock oscillator to its left. These form the actual VHF-UHF RF synthesiser ‘heart’ of the module. The two complementary RF outputs emerge from pins 12 and 13 of IC2, and are fed via 1nF capacitors to the two SMA output sockets at far right. The 3.3V DC supply to pins 12 and 13 flows via inductors L2 and L3. Only the RF output from pin 12 of IC2 (RFout+) has an onboard 51W terminating resistor. The other components on the righthand side of Fig.1 are to provide IC2 44 Silicon Chip Australia’s electronics magazine siliconchip.com.au Fig.1: the circuit diagram for the Geekcreit signal generator module. with power, set its operating mode, or feed it control signals. For example, the components between pins 7 and 20 at upper right form the ADF4351’s lowpass loop feedback filter (to optimise its performance), while the capacitors at pins 19, 23 and 24 bypass key reference points in its internal circuitry. The digital control signals from IC1 that direct IC2’s operation are fed to pins 1, 2, 3 and 4 at centre left, labelled CLK, DATA, LE and CE. The only other signal that passes back from IC2 is the LD (lock detect) signal from pin 25, which is high when IC2 is locked to the requested frequency. As well as being fed back to the MCU, this signal is also used to illuminate LED2, the blue lock indicator. The power supply section is at upper left in Fig.1. This accepts either 5V DC from mini USB socket CON2, or 5-15V DC from concentric DC socket CON1. This flows via on-off switch S7 to power indicator LED1 and the rest of the circuit. The incoming supply powers REG1 and REG2, both of which are LT1763 LDO (low drop-out) 3.3V linear regulators. REG1 provides 3.3V to the control siliconchip.com.au circuitry, while REG2 generates a separate 3.3V supply for synthesiser IC2. The incoming supply to REG2 is via T1-T2, a balanced decoupling transformer wound on a small ferrite balun core. As mentioned earlier, the control circuitry is based around IC1, an STM32F103C8T6 microcontroller, and the 128 x 64-pixel OLED display module to its right. The four digital signals to control synthesiser IC2 connect to pins 25-28 of IC1, while the LD signal from IC2 is fed back to pin 29. Pushbuttons S1-S5 at lower left select the operating mode of the synthesiser, its operating frequency, output level and so on. The MCU provides a series of menus and indications on the OLED display to make this reasonably straightforward. The OLED display is driven via an SPI serial control link from pins 14-17 of IC1. The instruction and master clock for IC1 is generated by an internal oscillator using 8MHz crystal X2, connected to pins 5 and 6. Pushbutton S6 manually resets IC1 if necessary. The D- and D+ data lines from mini USB socket CON2 are Australia’s electronics magazine connected to pins 32 and 33 of IC1, so its firmware can be updated from a PC if needed. It’s also possible to communicate with IC1 via a second serial link connected to pins 34 and 37, brought out to the pins of CON5. This is not a physical connector, but provision on the module’s PCB for fitting a four-pin SIL header. Trying it out When I received the unit and tried powering it up, there were a couple of problems. The first of these was that the DC supply cable provided with it turned out to have an open circuit in its red (positive) lead. So I had to discard it and substitute a known-good cable. Then when I powered it up, I found that the module was on regardless of whether power switch S7 was pressed or not. The cause turned out to be a solder bridge under the PCB joining its two active pins permanently. Luckily, I fixed that easily with a soldering iron. I also tried powering the unit from a 5V USB plug pack, using the USB Type A-to-mini Type B cable provided, which worked fine. December 2021  45 Fig.2: plot of the output level vs frequency when terminated by 50W. When the module is first powered up, the OLED screen shows its function menu, or more accurately, the top of it – listing the first three functions: 1. Point: used to set the module’s frequency to a particular figure, like 4375.05MHz 2. Sweep: used to set the start and stop frequencies for sweeping over a range 3. Step Fre: not clearly explained, but seems to be used to set the frequency steps used during sweeping Then if you continue pressing the down (DWN) button, S5, you find the remaining two options: 4. Step Time: not clearly explained, but it appears to be for setting the time between steps when sweeping 5. dB Set: see below When you press the OK button (S4) to select this last option, you get a screen giving a choice of four RF Power settings: +5dB, +2dB, -1dB or -4dB. These appear to be provided to allow ‘fine adjustment’ of the module’s RF output level. When I tried checking these output level options with the module’s frequency set to 1GHz using my Agilent V3500A power meter, I obtained the following results: • With the +5dB setting, the meter registered +3.60dBm • With the +2dB setting, it registered -0.24dBm • With the -1dB setting, it registered -1.99dBm • With the -4dB setting, it registered -4.52dBm These were all measured with the meter connected to the RFout+ On starting the module, the OLED display lists the five available functions. 46 Silicon Chip Australia’s electronics magazine connector, using a very short (<20mm) SMA-SMA coupler. So the reference (0dB) level appears to be around -1dBm, and while these settings are not particularly accurate, they give you the ability to adjust the unit’s output level somewhat. The next step was to measure its RF output over the whole frequency range, again using the V3500A power meter. I did these measurements again using the SMA-SMA coupler, connected between the power meter and first the module’s RFout+ connector, and then the RFout- connector. In each case, the output not being measured was terminated in 50W, to hopefully prevent any standing wave disturbances. As you can see from Fig.2, the level from the RFout+ connector is about 4dBm lower than that from the RFoutconnector, probably due to the loading from the onboard 51W terminating resistor across RFout+. But apart from that, both plots are relatively flat, rising slowly by about 2-3dB between 40MHz and 1GHz, and then wobbling a bit to return very close to the 1GHz level at 4.4GHz. So overall, both outputs were within the range of -4dBm to +4dBm over the entire frequency range. Next, I checked the module’s RF output signal purity at several different frequencies, using my Signal Hound USB-SA44B spectrum analyser with the latest version of Signal Hound’s ‘Spike’ software. The results were reasonably acceptable, bearing in mind that the module’s outputs are essentially square waves with significant harmonic content, along with the inevitable spurs you tend to get from any PLL-type synthesiser. To illustrate this, Fig.3 shows the module’s output at 2.5GHz, with the analyser set for a 60MHz span (ie, 30MHz either side of 2.5GHz). The main output is a reasonably clean peak reaching about +1.5dBm in the centre, with two small spurs at about -55dBm around 25MHz either side. So far, it looks reasonably clean. But now look at Fig.4, which shows what the analyser displays when set to span over the total frequency range from 50MHz to 4.4GHz, with the module still set to 2.5GHz. Several additional spurs are visible, spaced at about 620MHz apart on either side of the main output, with amplitudes varying between about siliconchip.com.au -6dBm and -18dBm. So the output is not nearly so clean as Fig.3 suggests. The full-scan plots don’t look so bad with the module set to higher frequencies, though. For example, Fig.5 shows the result when the frequency is set to 3.0GHz, while Fig.6 shows a similarly clean plot when it is set to 4.0GHz. On the other hand, Fig.7 shows the result with a full scan showing what happens when the module is set to produce a 100MHz signal. There’s now a virtual ‘forest’ of spurs, varying in amplitude from -10dBm down to about -49dBm in alternating steps. Not a pretty picture! Because of the lack of information regarding how to get the module sweeping or stepping from one frequency to another, I gave up trying to test those functions. Fig.3: a graph of the module’s output at 2.5GHz with a 60MHz span provides a reasonably clean plot with just two small spurs at the edges. Fig.4: the span is now set over the range 50MHz to 4.4GHz with the same 2.5GHz output. Note the additional spurs approximately 600MHz apart. Summary So although the Geekcreit 35MHz4.4GHz signal generator module is a low-cost, self-contained unit that can generate output signals of around 0dBm (1mW) over that wide frequency range, it does have a few drawbacks and limitations. One of these is the lack of much information on operating the module, especially with regard to getting it to perform sweeping. Another is the large number of ‘spur’ components in the outputs, especially when it’s generating a frequency below about 1GHz. That is because its outputs are essentially square waves, rather than the sinewaves that are needed for many signal generator applications. Filtering these to produce a smoother signal is virtually impossible due to the wide range of possible output frequencies; however, external filters could be used if you need cleaner signals at specific frequencies. And finally, because of its lack of any shielding (especially for the RF generation circuitry around the ADF4351), it would be tough to achieve accurate control over its output level. But overall, the module would still be useful, for example, if you want to generate digital clock signals over a very wide range of frequencies. Just bear in mind that to use it as the basis of a practical VHF/UHF signal generator, you’d have to add shielding, output filtering and a wide-range output attenuator system. SC siliconchip.com.au Fig.5: setting the output frequency higher to 3GHz also provides a clean plot. Fig.6: the output frequency now set to 4GHz. Fig.7: setting the module to an output frequency of 100MHz produces a large number of spurs at the harmonic frequencies (ie, multiples of 100MHz) with varying amplitude. Australia’s electronics magazine December 2021  47 Hands-on with Tim Blythman Raspberry Pi is a trademark of the Raspberry Pi Foundation The Raspberry Pi Pico Microcontroller The Raspberry Pi Foundation (www.raspberrypi.org) is well known for its range of inexpensive single-board computers, firmly aimed at the educational market but used by many others. Now they have released a very low-cost microcontroller board with an interesting set of peripherals. O ver the last ten or so years, the Raspberry Pi Foundation has continued to surprise us (in a good way) with their range of Raspberry Pi SBCs (single-board computers). These tiny boards have been used from embedded applications through to fully-fledged desktop machines. Over 30 million units have been sold since they were introduced, undoubtedly helped by very attractive pricing. We have reviewed several of these, including the model 3B+ (July 2018; siliconchip.com.au/Article/11141) and the 4B (August 2019; siliconchip. com.au/Article/11772). These boards can run the Raspberry Pi Foundation’s Linux-based desktop operating system, now known as Raspberry Pi OS. Earlier versions were known as ‘Raspbian’ as a nod to their Debian Linux roots. In addition, other third-party operating systems have been produced and ported to the various Raspberry Pi computers. Some operating systems turn these boards into media centres or retro gaming consoles. However, the boards’ target price of US$35 (currently about $46) also means that they are well suited for their primary intended use as an educational computer. The minimalist Raspberry Pi Zero boards can be had for under $10; we used one in our Speech Synthesiser 48 Silicon Chip from July 2019 (siliconchip.com.au/ Article/11703). It’s incredible that something as powerful as a desktop computer from around twenty years ago can be so small and cheap. Pico board However, the new Raspberry Pi Pico cannot be used as a desktop computer; it is a microcontroller board featuring the Raspberry Pi Foundation’s own RP2040 microcontroller. Still, it echoes the philosophy of other Raspberry Pi products. The claimed target price is US$4, and we purchased our units from DigiKey and Core Electronics for roughly the equivalent in Australian currency (excluding shipping) of about $5.25. Unfortunately, being so cheap has meant that there have been minor delays in obtaining the Pico, presumably due to high demand as well as the ongoing chip shortages. They are also now available from Altronics. The low price also means that it should find a good following in the educational sector and various Like many other microcontroller boards, the Pico is suited to breadboard use, although it does not come with header pins. This is a cost-saving measure that we have seen on other Raspberry Pi products like the Pi Zero. We have fitted the three-pin SWD header with right-angled pins at the opposite end to the microUSB socket. Australia’s electronics magazine siliconchip.com.au Board Used in Clock RP2040 ESP8266 ESP32 PIC32MX470 SAMD21 Pico D1 Mini Various modules Micromite Plus Arduino MKR 133MHz 160MHz 240MHz 120MHz 48MHz RAM 264kB 80kB 520kB 128kB 32kB Flash external (2MB) external (4MB) up to 4MB 512kB 256kB Cores 2 x ARM 1 x Tensilica 2 x Xtensa LX6 1 x MIPS 1 x ARM Pins 56 32 48 64 48 GPIO 30 11 34 45 22 UART 2 1 3 4 1 SPI 2 1 4 2 1 I2C 2 software only 2 2 1 PWM 16 software only 16 5 12 ADC 4 x 12-bit 1 x 10-bit 18 x 12-bit 28 x 10-bit 7 x 12-bit USB host/device no OTG host/device host/device no WiFi WiFi & Bluetooth no no Radio Table 1: how the Raspberry Pi Pico (RP2040) compares to other ‘similar’ microcontroller chips. other diverse fields, as we have seen with the other Raspberry Pi products. The RP2040 chip The basic specs of this chip are shown in Table 1, compared to some other familiar parts. The Pico’s RP2040 microcontroller was designed internally by the Raspberry Pi Foundation. This not only helps to keep the cost down, but it also allows the chip to be customised, and we will elaborate later on the interesting and unusual peripherals that have been incorporated as a result. The RP2040 is based on the ARM Cortex M0+. Boards such as the Arduino Zero and MKR series also sport such a processor; it is well-established. It is a 32-bit processor and, as is fairly typical for those, runs from 3.3V. The chip does not have internal flash memory, instead needing an external serial flash chip. Thus, various flash memory sizes can be provided by simply changing the external flash. An internal cache means that the flash speed does not typically limit the processor’s operating speed, and there is an option to copy and run code from RAM. The chip does have 16kB of internal boot mask ROM. This includes ‘bootstrap’ code which initialises the chip siliconchip.com.au and can download firmware to the flash chip via USB flash drive emulation. It also provides some optimised floating-point, bit manipulation and memory functions. You can download the full (600+ page) data sheet which explains all this from siliconchip.com.au/link/abab Peripherals The RP2040 features a single-cycle hardware multiplier, dual processor cores and a DMA peripheral. All of these are handy for implementing signal processing type applications, amongst other things. While there are 36 pins that could be used for general-purpose I/O (GPIO), six of these are generally used for the flash memory interface (in four-bit QSPI mode), leaving 30 for practical use. Four of these remaining pins are connected to the analog-to-digital converter (ADC) peripheral, and can be used as analog inputs. Broadly, any of these 30 pins can be used with just about any digital peripheral (such as SPI, I2C, PWM or UART), but each pin only in specific roles and grouped as such. This is similar to the PIC32 peripheral pin select (PPS) system. Each physical pin also has so-called ‘pad’ settings that control features such as drive strength, slew rate, Australia’s electronics magazine The Tiny 2040 board (shown at triple actual size) might be worth considering if you need a smaller device with fewer pins. Despite its smaller size (18 x 21mm), it was more expensive than the Pico due to the way the Raspberry Pi Foundation discounts its products. input levels, pull-ups and pull-downs. These work independently of the peripheral that is driving the pin. There is a USB peripheral that supports both device (full-speed) and host (full-speed and low speed) modes. At the Pico’s price, we can see it being used simply as a USB ‘widget’; for example, emulating a keyboard, mouse or other simple devices such as a serial port. PIO Probably the most interesting peripheral is the PIO or programmable input-output block. It could almost be considered to be a unique microprocessor optimised for input and output functions. Rather than having its function set by registers, each PIO block is controlled by a state machine with a small program that can be changed at runtime. We’ve already seen people using the PIOs to generate HDMI-compatible DVI video signals (with some processor overclocking), so it is very versatile. There are examples at https://github. com/raspberrypi/pico-examples/tree/ master/pio, including driving devices like WS2812 serial LEDs and HUB75 LED matrices. There are also examples to reproduce standard peripheral functions such as SPI and UART. December 2021  49 The Pico board The Pico board measures 51 x 21mm, with a micro-USB socket at one end and a 3-pin serial wire debug (SWD) header at the other. The two sides are lined with 20-way castellated vias. As expected at the price point, none of the headers are populated. Apart from the RP2040 IC and its surrounding passive components, a 3.3V switchmode regulator (surrounded by the necessary passives) provides power for the board. The dual-mode (PWM/PFM) regulator can be controlled by the micro via GPIO23. A tactile pushbutton is used to enter bootloader mode at reset. There are no other buttons to effect a reset, so the simplest way to start the bootloader is to hold the button while plugging in the board. A solitary LED and its series resistor are connected to GPIO25, while you can use a divider connected to GPIO24 to detect the presence of USB power. Thus the full complement of I/O pins are not brought out to external headers. A 12MHz crystal and the flash chip in an 8-pin leadless package round out the component list. There are six test pads on the back of the PCB, along with a QR code, which appears to be a serial number. The back of the PCB also has the I/O pin labels. Four holes to suit M2 machine screws are present. The board is suitable for use with a breadboard by soldering on headers, mounting in an enclosure via the holes or even soldering to a larger carrier board. In short, the board is not overly adorned but has been well-designed to suit a wide range of purposes and end-users. For the price, we cannot complain. But wait, there’s more In addition to the Pico, the Raspberry Pi Foundation is also making bare RP2040 chips available for sale. In addition to this, several other boards are available with the same microcontroller, including some made by Sparkfun and Adafruit. Many of these boards have opensource schematics (the Pico’s is in its 30-page data sheet), so creating your own variant won’t be too hard, if you don’t mind soldering QFN parts! There is also an Arduino “Nano RP2040 Connect” board, including a WiFi chip. It isn’t as cheap as the Raspberry Pi Pico, but it’s good to see such broad support for the new chip. Programming As noted earlier, the bootloader ROM on the RP2040 provides a USB interface when the Pico is started with the bootloader button pressed. This shows up as a virtual USB drive, as seen in Fig.1. It’s not a real drive that can load and save files, but it does provide two small files for reference. We saw a similar system on the Curiosity Nano AVR128DA48 board we reviewed (January 2021; siliconchip. com.au/Article/14696). This allows programming (or uploading firmware) by a simple drag-and-drop process. The Pico is the same, although it uses the so-called UF2 file format rather than the HEX file that is otherwise commonly used. The UF2 format has been designed by Microsoft to make uploading simple for both the user and the microcontroller. It is documented at https://github.com/ microsoft/uf2 Probably the most significant consequence of this arrangement is that it is practically impossible to ‘brick’ the Pico. The USB interface is defined in an immutable ROM and can be accessed by keeping the bootloader pin low at reset or power-up. More info can be found at www. raspberrypi.org/documentation/ rp2040 including guides to getting started and various data sheets. Much of the software is open source, and there are also third-party tools becoming available; we’ll mention those that we found useful. Silicon Chip When we first obtained our boards, there were two main ways of programming the Pico provided by the Raspberry Pi Foundation. The first of these is Micropython. The Python language is provided with many Raspberry Pi OS distributions. It’s also possible to set up a compiled C environment. This is a bit more involved, both regarding setup and use, but it appears some people have created an installer to simplify the setup process. Even so, a lot of command-line interaction is needed. More recently, there is now also an Arduino Boards Manager add-on which means that the Pico (and other RP2040-based boards) can be programmed through the Arduino IDE. Micropython Micropython is a subset of the Python 3 programming language that is optimised for microcontrollers. Programming with Micropython is a bit like programming with MMBasic on the Micromite. It includes a read-evaluate-print loop (REPL) prompt, similar to many older home computers. You can type single commands and see their immediate effect or enter complex programs and run them. You can also develop code in a PC-based IDE (integrated development environment) and then run the program on the Micropython hardware. The Pico is not the only board that can run Micropython; many 32-bit boards (especially those with ARM processors) can do so, as can the ESP8266 and ESP32. One advantage of Micropython (and other Python variants) over BASIC is that the Python language is standardised, so it is easier to find and write libraries that can be imported. This, in turn, makes it potentially more powerful, versatile and portable. Micropython implements a simple filesystem on the flash chip to allow user programs to be installed and extra Fig.1: when the Pico’s bootloader is active and it’s plugged into a USB port, it appears as a virtual drive to which you can copy a firmware file. The bootloader code is in a mask ROM baked into the RP2040 microcontroller at the factory, so all RP2040-based boards should have this feature. The Raspberry Pi Pico is built on a tiny 51 x 21mm board and is shown at actual size above. 50 Software Australia’s electronics magazine siliconchip.com.au libraries and other files to be loaded. With ample flash available, the Pico is well-suited to this role. Getting started with Micropython on the Pico is a simple case of loading the UF2 firmware file and then opening a serial terminal program to interface to the serial port, where the REPL prompt and interaction occur. Fig.2 shows several commands being issued at the prompt, including one to list the included modules. A module is what might be called a library file in other languages. For example, the “machine” module supports various I/O functions, including the ADC, pulse-width modulation (PWM) and communication peripherals such as SPI and I2C. You can find more information about Micropython and the UF2 files needed to run Micropython on the Pico at https://micropython.org/download/ rp2-pico/ Example Micropython code for the Pico can be found at https://github. com/micropython/micropython/tree/ master/examples/rp2 Note that the RP2 designation is the superset of microcontrollers which includes the RP2040 used in the Pico. Fig.2: Micropython will run on the Pico. It has an interactive prompt and a flash-based filesystem that can hold user programs and libraries. Although the language is a subset of Python, the overall feel is similar to BASIC computers like the Micromite. Fig.3: utilities like the Project Generator make C development quite easy once the environment is set up. Many compiler options are hidden by simply using the “nmake” command to initiate the compilation process. C language SDK Most of the microcontroller programming that we do is in the C language, typically on PIC microcontrollers using the MPLAB X IDE, so we were keen to see how useful and easy this would be. It is very much dependent on working with a command prompt. We found a few GUI tools to help set up projects, but you need to provide your own text editor. The documentation page has links for the C SDK (software development kit) in a GitHub repository and a script for setting this up on a Raspberry Pi and other Linux computers. It also includes several example programs. The SDK requires various other programs to be installed to provide a complete development environment, and we were not able to set this up successfully on a Windows PC. However, this appeared to be a problem with just one of the necessary programs, which hopefully has been fixed by the time this article is published. Fortunately, someone has bundled together all the necessary components in a simple installer, which you can find at https://github.com/ndabas/ pico-setup-windows siliconchip.com.au We recommend this alternative for those who are comfortable programming in an IDE, unless you are familiar with manually setting up compiler toolchains. This also installs some example programs and a project generator utility. This utility is used to set compiler options beyond what can be configured by the source code. This is shown in Fig.3; it is started with the “pico_project.py –gui” command from the pico-project-­generator folder. Australia’s electronics magazine There is also a “pico-env.cmd” file that can be used to set up a prompt with the appropriate environment variables. We found it handy to create shortcuts to these two utilities, as we were accessing them often. After doing that, we had no trouble copying bits and pieces from the example code into our generated C file. Then, to compile it, we changed to the “build” subdirectory and ran the “nmake” command. This resulted in a UF2 file in the build subdirectory, ready for uploading. December 2021  51 We haven’t tried it but we expect that for those who have installed the SDK on a Raspberry Pi or other Linux machine, the experience will be much the same, perhaps except for the use of “make” instead of Microsoft’s “nmake”. Arduino The Arduino Team has recently released the Arduino Nano RP2040 Connect board, although we have not tested it yet. We think this will be a handy board, as it will incorporate the NINA-W102 WiFi and Bluetooth radio module, as seen in several other Arduino boards. That includes the MKR Vidor, which we reviewed in March 2019 (siliconchip.com.au/ Article/11448) They also announced that the Arduino IDE (specifically, the Boards Manager) would support other RP2040 based boards, including the Pico. In fact, this support is already available, so we were able to test out programming the Pico using the Arduino IDE. This is as simple as searching for “RP2040” in the Boards Manager and installing the “Arduino Mbed OS RP2040 boards”. Mbed OS is a platform for developing on ARM microcontrollers. We found an interesting catch-22 while trying to use this board profile. It assumes that each board is assigned a serial port for programming. This is not necessarily the case with a new Pico and definitely not in bootloader mode. Once a sketch has been uploaded, it includes a serial port, but the difficulty is in performing the first upload. We found the easiest way to get around this was to use the Sketch → Export Compiled Binary option to generate a UF2 file, then use the bootloader to install it. After this, we could see and select a serial port as for other Arduino boards. Sometimes the port number changed, but that was easy to fix. As an aside, we found another board variant at https://github.com/ earlephilhower/arduino-pico which also circumvents this problem. It is a third-party board profile that builds the binary using the C SDK that we mentioned earlier. Cleverly, it does not require a serial port for uploading, but can detect the presence of the virtual USB drive that the Pico’s bootloader creates and 52 Silicon Chip uploads the file that way. Thus it’s another handy way to rescue boards that the Arduino IDE otherwise can’t recognise. You can install it by adding a link to https://github.com/earlephilhower/ arduino-pico/releases/download/ global/package_rp2040_index.json in the Boards Manager Preferences. The window shown in Fig.4 includes the two board profiles that we tried. This version also includes support for some Picoprobe boards, as well as a board from Adafruit. Picoprobe A Picoprobe is essentially a Pico programmed with firmware that allows it to behave like an ARM SWD debugger and a USB-serial converter. As we noted in our review in June 2021 (siliconchip.com.au/Article/14890), the Arduino 2.0 IDE can perform in-circuit debugging, but requires a probe; it appears that the Picoprobe can fill that role. There are examples showing how one Pico can be used to debug another. Since many debugging interfaces can also be used for programming, the Picoprobe variants described use the Picoprobe interface instead of the serial port for programming. Other boards Apart from the Arduino Nano RP2040 Connect that we mentioned, there is also the Adafruit Feather RP2040, plus variants from Sparkfun and Pimoroni. We managed to get one of the Pimoroni boards, called the Tiny 2040, as seen in our photo. But it appears that demand is high for these very cheap boards, and supplies are being snapped up as soon as they become available. No doubt, these circumstances aren’t helped by current chip shortages. Conclusion Like the Raspberry Pi single-board computers, the Pico microcontroller board offers exceptional value and ease of use. The sheer number of ways that it can be easily programmed is pleasing to see. Assuming that supply can keep up with demand, we do not doubt that the Pico and other RP2040 variants will be used not just for education, but just about anywhere that a 32-bit microcontroller is needed. With HDMI-compatible video already being coaxed from the chip and native USB support, it is not a stretch to imagine people tacking this board onto a project for these peripherals alone. So like the Raspberry Pi, it will see a variety of uses. The Pico, as well as numerous other RP2040-based boards and accessories, are available (subject to supply constraints) from: • Altronics: siliconchip.com.au/ link/aba8 • Core Electronics: siliconchip. com.au/link/aba9 • Digi-Key: siliconchip.com.au/ SC link/abaa Fig.4: we tried two different Arduino board profiles for working with RP2040 boards like the Pico. The Arduino team has also announced the Arduino Nano RP2040 Connect board, which will include a WiFi chip like many other recent Arduino boards. Australia’s electronics magazine siliconchip.com.au k n i h T ts. f i G er k r. a a M c y a J k n Thi 24 21 ale r, 20 On S mbe Dece 6 2 er to 149 $ b m Nove NOW BEST SELLER SAVE $20 Portasol Super Pro Gas Soldering Tool Kit Adjustable tip temperature up to 580°C with equivalent power of between 25W and 125W. Includes 4 tips, cleaning sponge & case. TS1328 DUAL COLOUR PRINTING DON'T FORGET YOUR SOLDER! 15g, 200g, & 1kg Available FROM $2.75 NOW 99 $ SAVE $30 4.3" COLOUR TOUCH SCREEN CLUB OFFER Ultra-high current 1000A AC and DC current measurement. CAT III, 6000 count. Data hold, backlight, non contact voltage, relative measurement and more. QM1634 FREE $100 GIFTCARD JUST 2495 $ 1000A True RMS AC/DC Clamp Meter PCB Holder with LED Magnifier Ideal aid for soldering work, model making etc. 2x magnification. TH1987 IDEAL FOR MID-SIZED WEB MEETINGS JUST 1299 $ Creality Dual Filament 3D Printer CR-X NEW NEW 59 $ Create amazing high-quality prints with two colours or materials. Dual cooling fans. SD memory card slot. Prints up to: 300Lx300Wx400Hmm. TL4410 JUST 7995 $ ONLY 95 Omnidirectional USB Conference Microphone Add sound quality to your Zoom, VoIP, Wechat meetings and chats. Plug & Play. Compatible with Mac OS X, Windows PC. AM4137 IMPROVE YOUR PODCASTING Wireless Lavalier Microphone for Smartphone and Camera Improve your podcasting or audio recording. Includes a Transmitter and Receiver. AM4138 BUILD AND PLAY WITH YOUR KIDS SPREADS ITS FRILLS ONLY 3995 $ 229 PIECES Hydraulic Cyborg Hand Kit Simulates the movements of your hand. Adjustable joints. Ages 10+. KR9266 Shop the catalogue online! JUST 3995 $ FOLLOWS, RUNS AWAY Smart Frilled Lizard Kit Build this interactive lizard. 370mm long. Ages 10+. KJ8968 29 $ Travels up to 80m on one single tank. No batteries or motor required. 190mm long. Ages 10+. KJ8967 Exclusions apply - see website for full T&Cs. * 95 Air Power Engine Car Kit Free delivery on online orders over $99* JUST 1995 $ JUST 6-in-1 Solar Robot Build robots out of a can or water bottle. Ages 10+. KJ8939 www.jaycar.com.au 1800 022 888 Gifts for your Workbench 100MHz Dual Channel Oscilloscope 7” colour LCD. Built-in waveform generator. PC connection via USB. SD card support. Lightweight and compact. Includes 2 probes & USB cable. QC1936 CLUB OFFER 699 $ SAVE $200 60W ESD Safe Soldering Station HIGH TEMP STABILITY SAVE $30 NOW 129 $ NOW 129 $ Powerful 60W heating element. 160-480°C temperature range. Celsius or Fahrenheit temperature display. Mains powered. TS1640 0-36VDC 0-5A Slimline 80W Lab Power Supply SAVE $30 Powerful and compact. Constant current and voltage options. Includes banana to alligator clamp leads. MP3842 4.3" OLED DISPLAY ADJUSTABLE STAND JUST 2995 $ NOW 39 $ 27 PIECES 95 SAVE $10 Smartphone Repair Kit 73 PIECES 73 Piece Screwdriver Set Contains all necessary tools you need to fix your Smartphone from 4mm bits, tweezers & more. TD2118 Open all kinds of electronic devices. S2 Steel precision bits. Storage case. TD2136 NOW NOW 99 49 $ $ 95 SAVE $30 SAVE $10 Desktop Magnifier with LEDs 100mm 3-dioptre glass lens provides powerful magnification. Changeable lens. QM3552 1080p Digital Microscope Up to 600x magnification. LED illumination. Built-in rechargeable Li-ion battery. QC3193 GIFT QUALITY HAND TOOLS CURES UNDER UV BEST SELLER BUY BOTH FOR JUST 1695 $ Crimping Tool for Non-Insulated Lugs Suits 14-18 & 22-26 AWG lugs. Builtin wire cutter. 185mm long. TH1834 20 $ SAVE $9.90 Precision Cutters & Pliers 127mm Angled Side Cutters TH1897 $14.95EA 150mm Long Nose Pliers TH1887 $14.95EA JUST 32 $ 95 Heavy Duty Wire Stripper, Cutter & Crimper Strip all types of cable from 10-24 AWG (0.13-6.0mm). 204mm long. TH1827 Not sure what to build next? Here's some inspiration: jaycar.com.au/projects NOW 3995 $ SAVE $5 Bondic Liquid Plastic Welding Kit Bond, build, fix & fill virtually anything in seconds. Solvent-free. NA1530 Gifts for your Workbench BUILT-IN HD CAMERA & WI-FI SUPPORT CLUB OFFER CLUB OFFER GIFTCARD GIFTCARD FREE FREE $100 $100 STURDY ALUMINIUM BODY JUST 1299 1349 $ $ CONTROL PANEL WITH 4.3" COLOUR SCREEN JUST NEW 499 $ 3.5" TOUCHSCREEN Flashforge Adventurer 4 3D Printer 3-in-1 3D Printer, CNC & Laser Etcher 3D print, engrave & laser cut with a single machine. Easy swap & interchangeable modules. Includes easy to use software. Prints up to 125Lx 125Wx125Hmm. TL4400 Large print volume of 220Wx200Dx250Hmm. Features include a levelling-free removable print bed, quick release nozzles & a HEPA13 air filter. TL4431 Due early December. JUST 2495 Non-contact AC Voltage Detector Detects AC voltages from 200V to 1000V. Flashlight function. QP2268 NOW FROM 4995 $ PIECES Digital Multimeter with Temperature Measures voltage, resistance, capacitance, temperature and more. CATIII 600V 10A. 4000 count display. QM1323 19 95 SAVE $5 Contains 160 lengths of different sizes in a handy storage case. WH5524 95 SAVE 25% Liquid Electrical Tape Seals and protects electrical connections. 118ml can or 28g tube. Black or red available. NM2832-NM2838 ARDUINO® COMPATIBLE This icon indicates that the product will work in your Arduino® based project. 95 Ultrasonic Cleaners Mini Bench Scales Extremely accurate. 0.01g Resolution. Weighs in grams, carats, and pennyweight. 100g QM7258 $49.95 200g QM7259 $69.95 Effectively clean your jewellery and other small parts. Mains powered. 400ml 40W YH5414 NOW $69.95 SAVE $20 1.8L 80W YH5416 NOW $119 SAVE $30 STOCK UP ON YOUR ESSENTIALS NM2832 14 $ SAVE <at> $30 FROM 49 $ NOW FROM NOW 6995 $ JUST NM2836 160 160pc Heatshrink Pack Large build volume of 220Lx220Wx250Hmm. Resume printing function. Filament auto feeding. Support PLA, ABS, & PETG type filament. TL4432 0.01G RESOLUTION EASY TO USE AUTORANGING METER $ Entry Level 3D Printer BEST SELLER GREEN & RED LED INDICATORS $ JUST NOW 3495 $ SAVE $5 25M ON EACH ROLL Light Duty Hook-up Wire Pack Quality 13 x 0.12mm tinned hook-up wire on plastic spools. 8 different colour rolls included. WH3009 NOW 3995 $ SAVE $5 300 PIECES 300pc QC Crimp Connector Pack Bullet, ring, fork, spade and joiners in various sizes and colours. PT4536 RASPBERRY PI COMPATIBLE This icon indicates that the product will work in your Raspberry Pi project. Gifts to Make & Build JUST 1995 $ JST Connectors Kit Includes the popular JST XHP 2.54mm and PH 2.0mm housings & headers. Used for prototyping, repairs, and hobby applications. PT4457 NOW 34 $ 95 89 $ INCLUDES UNO BOARD SAVE $5 NOW 1495 SAVE 30% SAVE $20 Arduino Compatible Starter Kit INCLUDES MEGA BOARD Arduino Compatible MEGA Experimenter’s Kit ® ® Includes UNO board, jumper leads, resistors and more to get you started in the world of Arduino®. XC3902 Make it with UNO Boards Arduino® Compatible Solderless Breadboard with Power Supply Includes 830 tie-point breadboard, power supply module. Power from USB or 12V plugpack. PB8819 NOW 2495 $ SAVE $5 240x320 LCD Touch Screen Large, colourful touch display shield which piggybacks straight onto your UNO or MEGA. microSD card slot. 77Lx52Wx19Hmm. XC4630 5995 2995 $ Stackable design makes adding shields easy. Powered by a USB-B cable or 7-14VDC. ATMega16u2 USB-Serial chipset. 53Lx75Wx13Hmm. XC4410 80 9 Operates directly from 5V. SPDT relays. 10A rated. XC4419 $5.45EA NOW 995 $ SAVE $10 * 9.95 4 x 4 x 4 Blue LED Cube Kit Learn to connect and program basic Grove modules that includes both sensors and actuators along with the Arduino® UNO Board (XC4410 $29.95 sold separately). XC9201 SAVE 15% More ways to pay: Buy Sensor Kit & UNO Board for Arduino® Sensor Kit $ 5V Relay Board BUNDLE DEAL $ 64 ULTRABRIGHT LEDS HALF PRICE! SAVE $9.90 2 FOR DOUBLE UP JUST $ JUST UNO R3 Development Board & SAVE ON MODULES INCLUDES 64PCS MIXED JUMPER LEADS Includes MEGA board, breadboard, jumper wires and plenty of prototyping hardware & peripherals in a plastic organiser. XC4286 BEST SELLER NOW $ 2 FOR 10 $ SAVE 15% PIR Motion Detector Module Add motion detection to your project. 0.3-18s adjustable delay. 5-20VDC. XC4444 $5.95EA Build a dazzling array of ultra-bright blue LED’s which alternate between fifteen different patterns. Requires Arduino® UNO Board (XC4410 $29.95) sold separately. KM1097 2 FOR 35 $ SAVE 10% 1.3” 128 x 64 OLED Monochrome Display Module Wide viewing angle to eliminate eye strain. 39Lx36Wx6Dmm. XC3728 $19.95EA Gifts to Make & Build NOW 89 $ 3995 $ NOW WITH BUILT-IN MIC & SPEAKER SAVE $40 JUST micro:bit GO V2 Development Board Bundle Upgraded model! Touch sensitive logo. Power indicatior. Includes micro:bit board, batteries, battery box and USB cable. XC4324 SuperBot Robot Kit BUNDLE DEAL Build 18 cool multi-functional models. Allows kids to do coding by graphical programming language. 400 pieces. Ages 8+. KJ9354 iPad not included Buy Robot Kit, micro:bit & Battery For 119 $ LEARN ROBOTICS & CODING SAVE $16.85 NEW NOW 6995 $ ONLY Starter Kit with micro:bit v2 Meet Edison Robot Kit Includes micro:bit v2 board, resistors, servo and all the necessary prototyping accessories to get you started in the world of electronics and coding. XC4326 Compact, pre-programmed with 6 robot activities. Can be programmed using simple drag-and-drop programming blocks. Ages 5+. KR9210 JUST Smart Robot Kit for micro:bit Fun to build robot that uses a micro:bit board (sold separately) that you can code or control using Smartphone via Bluetooth®. Plug and play. KR9262 2500mAh 3.6V 18650 Battery to suit SB2298 $25.95 The perfect gift for a maker, guaranteed! HALF PRICE! 2495 NOW 80W 240V Soldering Iron SAVE $5 SAVE $15 Christmas Tree Kit Includes tree shaped circuit board, coloured LEDs, and electronic components. Add an Arduino® UNO board (XC4410 $29.95 sold separately) to create amazing lighting effects. Soldering required. XC3754 49 95 SAVE $10 Hydraulic Robot Arm Kit Lift up to 50g. Hydraulic power. No motors, no batteries required. Ages 10+. KJ8997 Up to 530°C temp range. Stainless steel barrel. Electrically safety approved. TS1485 NOW 1495 $ NOW JUST $ 495 $ 9.95 6995 $ 9995 $ SAVE $30 $ * HALF PRICE! Santa Sleigh Kit Includes 126 multicolour flashing LEDs, with a clever circuit that creates the illusion of a flying reindeer while Santa's hat flaps in the wind. Soldering required. XC3756 NOW 2495 $ SAVE $4 Salt Water Fuel Cell Engine Car Kit Demonstrate the concept of a salt powered automotive engine. 120mm long. Ages 8+. KJ8960 Looking for more product information? Visit your local store or our website jaycar.com.au NOW 1195 $ SAVE 40% Desktop PCB Holder Hold PCBs of up to 200 x 140mm. Adjustable angle. TH1980 PCB not included ONLY 24 $ 95 Cardboard Radio Construction Kit Make your own AM/FM radio. No soldering required. Requires 3 x AA batteries. Ages 8+. KJ9021 4 x AA Batteries SB2425 $3.25 JUST 1495 $ Mini Motor Experiment Kit Demonstrates the basics of how the magnets, armature and commutator work together in an electric motor. Ages 8+. KJ9032 We reward our industry professionals Christmas Savings 3" SCREEN NOW 4995 $ REVERSED IMAGE REFLECTS CORRECTLY ONTO WINDSCREEN DASH CAM & REVERSING CAMERA IN 1 NOW 149 $ SAVE $10 1296p 140° view front camera with rear camera doubling as a reversing camera. Automatically records on impact to microSD card (sold separately). 12/24VDC operation. Auto on/off. QV3849 32GB microSD Card XC4992 $36.95 NOW 49 $ JUST 69 95 Diagnose your cars problem. Plugs into OBD-II port and transmits speed, RPM, fuel consumption, etc via Bluetooth® to your Smartphone. PP2145 NOW 4995 95 $ SAVE $20 OBD-II Engine Code Reader with Bluetooth® SAVE $30 SHD Car Dash Camera with GPS & Rear Camera Keep your eyes on the road and read important driving info such as speed, from a head up display reflected off the windscreen. OBD-II or GPS operation. Auto brightness adjustment. LA9036 Measures from 2 to 99,999 RPM. 5-digit backlit LCD. Integrated laser pointer. Built-in memory recalls. Carry case included. QM1449 Wireless Reversing Camera Kit with 7” LCD 2.4GHz digital. Help see through blind spots. Up to 80m range with crystal clear picture. 12V/24VDC. QM8046 JUST 1795 $ SAVE $15 Digital Tachometer NOW 299 $ SAVE $50 Head Up Display Speedometer with GPS & OBD-II Data $ IDEAL FOR 4WDS & LARGE VEHICLES Automotive Multi-Function Circuit Tester with LCD Tests electrical system of a vehicle running on 12V or 24V. Tests voltage and polarity of a circuit, continuity check and more. QM1494 Automotive Crimp Tool with Connectors Cut and strip wire and crimp connectors. 80 pieces. TH1848 SAVE ON SOUNDS AMAZING SOUND NOW 6995 $ GREAT FOR TV OR MUSIC SAVE $10 2 Channel Soundbar Speaker with Bluetooth® 5.0 Enhance the sound of your TV or use as a standalone speaker. Includes 3.5mm stereo and digital optical inputs. 2 x 14W Output. Wall mountable. XC5233 NEW LOW PRICE JUST 119 $ BUILT-IN MIC Active Noise Cancelling Wireless Earbuds Features True Wireless Stereo (TWS) and Active Noise Cancellation (ANC) to provide amazing stereo sound. Recharging case. Bluetooth® 5.0 technology. AA2149 NOW 39 $ 95 SAVE $5 Portable Mini Boom Box with Bluetooth® Pump up the sound with this portable 8.5WRMS Bluetooth® speaker. Built-in FM radio. CS2469 ONLY 2995 $ Dancing Santa Bluetooth® Speaker Play your favourite festive tunes via your Smartphone. Dances to the music. GT4300 NEW 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. IN-STORE ONLY refers to company owned stores and not available to Resellers. Page 1: CLUB OFFER: FREE $100 Gift Card with purchase of Dual Filament 3D Printer (TL4410). Page 2: Buy 1 x TH1897 + 1 x TH1887 for $20. Page 3: CLUB OFFER: FREE $100 Gift Card with purchase of 3D Printers TL4400 and TL4431. Page 4: Bundle Deal: 1 x Arduino Sensor Kit (XC9201) + 1 x UNO Board (XC4410) for $80. Page 5: Bundle Deal: 1 x micro:bit v2 Board (XC4324) + 1 x Robot Kit (KR9262) + 1 x 18650 Li-Ion Battery (SB2298) for $119. Page 7: Gamer’s Bundle includes 1 x Headphones (AA2126) + 1 x Keyboard & Mouse Set (XC5132) + 1 x Gaming Pad (XM5101) for $89. Page 8: CLUB OFFER: FREE $100 Gift Card with purchase of 4K Resin 3D Printer (TL4421). SUPPLY CHAIN DISRUPTION. We apologise for factors out of control which may result in some items may not being available on the advertised on-sale date of the catalogue. View live or playback video on your TV or monitor or remotely via Smartphone or Tablet using free app. SAVE $150 NOW 399 $ NOW 849 $ Christmas Savings SAVE $50 4K 2TB HDD 1TB HDD 1080P Concord 4 Channel HD DVR Kit with 4 x 1080p Cameras Concord 8 Channel 4K NVR Kit with 4 x 5MP Cameras • Smart viewing and notification • PIR movement detection with push notification • Built-in infrared LEDs for night vision up to 20m • Expandable to 6 channels (4 x AHD and 2 x IP cameras) • IP67 rated camera QV5050 • Smart viewing and notification • PIR movement detection with push notification • Built-in infrared LEDs for night vision up to 30m • Expandable to 8 x 5MP cameras • IP66 rated camera QV5600 ALL KIT CONTENTS INCLUDE: Digital Video Recorder (or Network Video Recorder). Cameras, Power and Video Cables, Adaptor and Splitter. USB Mouse, HDMI Cable and Network Cable. 2.4" LCD JUST 29 $ 95 Plug-in Wireless Doorbell Compact sized, plugs straight to a power point. 36 selectable melodies. 240VAC. LA5029 Camera Detector Protect your privacy! Detects hidden wired and wireless cameras. QC3506 2 x AAA batteries SB2426 $1.95 NOW 95 SAVE $10 USB Retro Arcade Game Controller Pairs with any USB compatible gaming system. Suits PC, Nintendo Switch, Raspberry Pi, PS3 & Android TV Arcade Games. USB powered. XC5802 NOW 3995 $ SAVE $10 DIY Game Console An Arduino-based handheld game console that you can code or upload your favourite Arduboy games. See website for details. XC3752 Monitor local wildlife or use as an outdoor security camera. 10sec-3min motion detection recording onto microSD card up to 32GB (sold separately). Water resistant housing. Time lapse recording. 2.4" LCD. Requires 8 x AA batteries (sold separately). QC8043 32GB microSD card XC4992 $36.95 12pk AA Batteries SB2333 $7.95 PAIRS TO A PHONE, TABLET, OR COMPUTER NOW 24 $ 1080P 1080p Outdoor Trail Camera SAVE $20 29 $ SAVE $30 NOW 7995 $ NOW 169 $ 95 SAVE $15 GAMER’S BUNDLE Designed for hardcore gamers who enjoy many hours of gameplay. Includes keyboard and mouse, gaming pad and headphones. Gaming Headphones with Microphone AA2126 $49.95 Gaming Keyboard and Mouse Set XC5132 $59.95 Ultra Durable Gaming Pad XM5101 $19.95 Bluetooth® Game Controller Get a better gaming experience from your Android and Windows games. XC5800 Smartphone not included. Available in: JUST 2995 $ Retro Style Handheld Game Console Features built in speaker and a 3.5mm to RCA and USB recharge cable. Ages 15+. GT4280 Looking for more product information? Visit your local store or our website jaycar.com.au BUY ALL FOR 89 $ SAVE 30% VALUED AT $129.85 The perfect gift for a maker, guaranteed! s a m t 4K HIGH RESOLUTION FOR HIGHLY DETAILED PRINTS s i r h s r C e k r ma fo JUST 499 $ Anycubic Wash & Cure Plus Machine Rotating curing platform with full 360° curing operation. 405nm UV light. TL4423 PRINTS LARGER SIZES AND 3X FASTER THAN EARLIER MODELS eSUN 3D Printer Resin 1kg PLA High precision, smooth surface. 7 colours. TL4433-TL4439 $59.95EA PLA Pro Higher resolution & precision. High strength & toughness. 3 colours. $59.95EA TL4440-TL4442 Standard High precision, high hardness & good wear resistance. 7 colours. $69.95EA TL4443-TL4449 FROM 5995 $ CLUB OFFER JUST FREE 1149 EA $ $100 GIFTCARD Anycubic 4K Resin 3D Printer Larger build volume of 192Lx120Wx245Hmm. 8.9" 4K LCD. Fast printing speed (3 x faster than previous models). More detailed prints compared to filament-type printers. Uses Anycubic App to remotely control print operations, monitor printing progress etc. TL4421 PERFECT GIFT FOR A MAKER IN THE MAKING MIRROR, HOOK & PICK-UP MAGNET INCLUDED HANDY KIT FOR THOSE QUICK AND URGENT REPAIRS NOW 129 $ NOW 99 $ SAVE $30 Pro Soldering Gas Kit Includes soldering iron, wire stripper, cutters, heatshrink and other accessories. Supplied in a hard plastic carry case. TS1115 JUST 169 $ SAVE $20 Inspection Camera with 2.4” Screen Arduino® Starter Kit This official kit from Arduino® includes UNO board, breadboard and plenty of prototyping accessories. XC9200 Excellent for inspecting or locating objects in tight spaces. 1m long gooseneck. QC8710 CHRISTMAS TIME! WORKING CLOCK & CALENDAR! MAKE OR REPAIR A CLOCK HALF PRICE! NOW 9 $ 95 SAVE $10 SHAKE TO GENERATE A RANDOM NUMBER Electronic Dice Kit Teach your kids and grand kids how to solder. CR2032 battery required. KM1099 NOW 9 $ 95 SAVE $10 9V Battery (SB2423 $4.50 sold separately) HALF PRICE! 3D Traffic Light Kit Take their soldering skills to the next level. Can place onto car or train set. 9V battery required. XC3758 JUST 16 $ 95 Quartz Clock Movement Self starting. Supplied with three sets of hands. XC0100 FROM 59 $ 95 250 PIECES 168 PIECES DIY Wooden Puzzle Kits Fun to assemble and will make a magnificent art piece on your desk or table. Ages 14+. Zodiac Wall Clock KJ9050 $69.95 Time Engine Calendar KJ9051 $59.95 LEARN, BE INSPIRED, PROJECTS, WORKSHOPS & MORE! 24/7. 1800 022 888 www.jaycar.com.au Over 100 stores & 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 confirmed at the time of print. Call your local store to check stock. Occasionally discontinued items advertised on a special / lower price in this flyer have limited to nil stock in certain stores, including Jaycar Authorised Resellers, and cannot be ordered or transferred. No rainchecks. Savings off Original RRP. Prices and special offers are valid from 24.11.2021 - 26.12.2021. Digital Lighting Controller Translator By Tim Blythman Last year’s Flexible Digital Lighting Controller project is a fresh design that controls mains-powered lights or addressable RGB LED lighting strips to create spectacular lighting shows. But many people have built our previous lighting controllers from 2010 & 2011. So that you can upgrade without redoing it all from scratch, this Translator allows all of the original Lighting Controller slave units to operate with the new system. T he Digital Lighting Controller published in the October, November & December 2010 issues (siliconchip. com.au/Series/14) allows up to 32 mains-powered incandescent lights or 12V LED strips to be choreographed to music. It is controlled by a master unit based around a dsPIC33FJ64 microcontroller which controls the lights and plays the music. As there weren’t many easier ways to do that at the time, quite a few were built, including from kits. We designed the Flexible Digital Lighting Controller (siliconchip.com. au/Series/351) 10 years later to supersede the older units. Similar in concept, it can control up to 64 lighting channels. It also uses trailing-edge siliconchip.com.au dimming instead of the older style leading-edge dimming that is only really suitable for incandescents. Trailing-edge dimming is ideal for modern mains-powered LED lamps as it mitigates inrush currents by switching on near the mains voltage zero crossing. It is fully compatible with incandescent globes too. We also designed a separate slave unit to handle so-called ‘smart’ low-voltage LED strings, published in December 2020. This includes the options to set up groups of multiple LEDs to cover a wider area. Thus, the new system can control either mains-powered or low-voltage LED lights. Both Flexible slave unit types are addressable, so a combination of mains and low-voltage LEDs can be driven by the same channel in synchrony. But the 2010/11 and 2020 systems are incompatible and use entirely different signalling protocols and control strategies. So it is difficult to upgrade a system using the older Digital Lighting Controller. For example, the older Digital Lighting Controller continually outputs data to precisely control each switching event in time with the mains waveform; there are around 2000 switching events per second. On the other hand, the Flexible Lighting Controller only transmits data if the display needs to change, with the slaves handling mains synchronisation. This small unit brings together the two different Digital Lighting Controller systems. It takes its input from any of the 2020 Flexible Digital Lighting Controller master units (which could just be an Arduino board) and can drive the older Digital Lighting Controller slaves from 2010 or 2011. Altronics still stocks kits for these slave units (Cat K5886 & K5887). The logical way to bridge this gap is with a protocol translator. The Translator we present here receives data in the ‘new’ format and transmits the ‘old’ format. This means that the master unit presented in November 2020 can be used to control the older slave units as well as the newer ones it is designed to interface with. This master from November 2020 is based around the Micromite BackPack hardware and offers a graphical interface lacking on the older unit. So you can now use this master to control any of the four different types of slave unit. It is also possible to use a USBSerial converter to control the Flexible Digital Lighting Controller slaves Australia’s electronics magazine The Translator December 2021  61 Fig.1: the Translator circuit uses the same optoisolated receiver scheme as the newer “Flexible” slave units. A pair of regulators provide the 3.3V and 6V rails needed to drive the older slaves, while four I/O pins produce the data using much the same interface as the original dsPIC33FJ64-based master unit. using a Processing sketch. In fact, the newer protocol is so simple that you can even use an Arduino board as the master of such a system. The old control protocol Both Digital Lighting Controller systems use logic-level signals transmitted over CAT5/CAT6 cable and terminated with RJ45 plugs (similar to Ethernet cables). But that’s really all they have in common. The older system passes 3.3V logic level signals over four of the conductors in the cable; these are used to drive the DATA, CLOCK, LATCH and RESET lines of a 74HC595 shift register. The shift register outputs are then used to drive either Mosfets (for the LED version) or Triacs (for the 230V version). The remaining four lines consist of 6V and 3.3V power supply rails, a ground and a chain length sense line. While the 230V version uses optoisolators in each slave to separate the mains voltage from the control signals, the LED version has no such provision. Thus much of the circuitry is tied to the same voltage rail. In fact, the master provides power and is directly connected to all shift registers in the chain. This system feeds data to the shift registers 20 times each mains halfcycle. The chain length sense line is used to detect the number of connected slaves and can thus reduce the amount of data sent if fewer than the full number of slaves are connected. It also needs to synchronise its data to the mains waveform so that the Features ● Allows Digital Lighting Controller slaves from 2010 & 2011 to be controlled by Flexible Digital Lighting Controller masters (described in 2020) ● 2010, 2011 & 2020 slaves can be mixed and controlled by a single 2020 Master unit ● Compact unit fits in UB5 Jiffy box ● Powered by 9V AC plugpack ● Uses standard CAT5/CAT6 Ethernet cables for wiring 62 Silicon Chip Australia’s electronics magazine Triacs are triggered correctly. It works well but demands high data rates and continuous attention from the master microcontroller. The new protocol The new system delegates much of the control responsibility to the slaves, which each have their own microcontroller. Each slave also has an optoisolator to isolate it from the bus and thus the master. The new protocol is inspired by DMX-512, which is used in professional lighting control systems. DMX512 uses RS-485 level differential signals at 250,000 baud. Our system uses a single-ended logic level signal at 38,400 baud because this is easier to produce and interpret. Like DMX-512, the start of a frame is marked with a ‘break’ condition on the serial data line; this is a period of around 13 bit times of low (not idle state) data level and is not a state that occurs otherwise during normal transmission. The first data byte is 0x00, which sets the frame type, meaning the subsequent data contains lamp brightness values. Other DMX-512 frame types siliconchip.com.au exist but are not used in our system. The actual data follows as consecutive bytes of serial data; the first byte after the 0x00 is sent to the first lamp, the next to the second and so forth, up to 64 lights. If you wish to implement your own master, you can also look at our Arduino and Processing code. The circuit Fig.1 is the circuit of the Translator, which has much in common with the Flexible Digital Lighting Controller slaves (described in the October & December 2020 issues). All three use 14-pin microcontrollers and 6N137 optoisolators to provide isolated reception of the data from the master. IC1 is a PIC16F1705 or PIC16LF1705 microcontroller, the same part as used in the 230V slave unit. CON4 is an ICSP header that you can use to program the chip. A 10kW resistor between pins 1 and 4 of IC1 pulls up the MCLR pin, while a 100nF capacitor provides local bypassing of the 3.3V rail that powers the microcontroller. Pins 1 and 2 of RJ45 jack CON1 are connected across the LED (pins 2 and 3) of OPTO1 with a 220W resistor in series. 1N4148 diode D1 provides reverse polarity protection to the LED by shunting current if power is applied in the reverse direction. In regular operation, the master applies +3.3V or 5V to pin 1 of CON1. Pin 2 will idle at the same voltage but is taken low when the master transmits a ‘0’ bit or a break condition. Thus current only flows when the master’s output is not at the idle voltage. OPTO1 is bypassed by another 100nF capacitor between its pin 5 (circuit ground) and pin 8 (3.3V). The output pin, pin 6, is pulled up by a 1kW resistor to the 3.3V rail. Thus, it idles at the same state as the master (high) with no current flowing. When the master transmits a ‘0’, current flows through OPTO1’s LED, and its internal circuitry causes its pin 6 to be pulled to ground. This scheme provides isolation while also maintaining the correct logic sense. Also, the disconnected state is the same as the idle state, which means the slave does not misbehave if it is not connected to a master. OPTO1’s pin 6 is connected to microcontroller IC1’s pin 5, which is configured to operate as a UART receiver at 38,400 baud. Green LED1 siliconchip.com.au in series with a 1kW resistor is also connected between the 3.3V rail and OPTO1’s output. It thus illuminates whenever the master transmits a ‘0’. While OPTO1 is probably not necessary for most applications, it is possible to connect the Translator to a computer to implement a ‘simple master’ using the Processing application. In this case, it is cheap insurance to avoid the possibility of any damage to the computer’s USB port. Keep in mind that there is no slot in the PCB, so OPTO1 will not provide isolation from mains voltages, and the clearance and creepage requirements are not met. Pins 8-11 of IC1 are connected to another RJ-45 jack, CON2, to produce data in the ‘old’ protocol. Each pin has a series 100W resistor to limit fault current and a 10kW pull-down resistor to set a safe default state while the microcontroller is starting up. For more detail on the operation of the old protocol, you can refer to the article in the October 2010 issue (siliconchip.com.au/Article/315). The pins provide the DATA, CLOCK, LATCH and RESET signals using IC1’s SPI and GPIO peripherals. IC1’s pin 7 (RC3) is connected to the CHAIN SENSE line of CON2 and is pulled down to ground by a 4.7kW resistor. Each slave has a 10kW resistor pulling this line up to its 3.3V rail, so the voltage on this pin depends on the number of slaves connected. Thus, the number of slaves can be determined by using the micro’s analog-to-digital converter (ADC) peripheral to read the voltage on this pin. Pin 3 (RA4) on IC1 is connected to a yellow LED through a series 1kW resistor to ground. It is used to flash error codes by the microcontroller’s firmware. Pin 6 (RC4) of IC1 is connected to one side of the AC supply input via a 1MW resistor and is used to detect the mains polarity and thus keep track of the mains phase. The resistor allows pin 6 to be pulled high or low by the AC waveform while limiting the current to a minimal level, so the micro’s input pin will not be damaged. Power supply 9V AC to power the circuit comes in through barrel jack CON3. We need to use AC power to allow the circuit to sense the phase of the mains waveform so that it can drive slaves controlling Australia’s electronics magazine mains-powered lights. An AC plugpack provides a safe and simple way of doing this, as well as providing power. Current flows into bridge rectifier BR1 and the resulting pulsed DC is filtered by the first of three 100μF electrolytic capacitors. REG1 is a 7806 regulator that provides a 6V rail stabilised by the second 100μF capacitor. A transformer driving a bridge rectifier and filter capacitor results in a high peak current draw as the AC waveform approaches its maximum amplitude. Therefore, a 10W series resistor has been added to limit the peak current. This reduces distortion of the AC waveform and thus improves zero-crossing detection. Red LED2’s anode is connected to the 6V rail, while its cathode is connected to circuit ground via a 1kW resistor. Thus LED2 lights up when power is present. The 6V rail also feeds REG2, an MCP1700 3.3V regulator, and a third 100μF capacitor to generate a 3.3V rail. The 6V and 3.3V rails are needed for compatibility with the slaves from the older system. Software Since many of the Translator functions are similar to those of the newer slaves, we reused some of that code. After the initial setup, the firmware does little more than check the peripheral interrupt flags to know if anything needs to be done, as there are no user inputs to monitor and act on. The setup code initialises the UART (to receive serial data from OPTO1) and SPI (for shift register data output) peripherals. A timer is set to fire around 7800 times per second. Also, the ADC peripheral is enabled, and the various I/O pins are configured for their respective roles. In the main loop, the UART is checked for incoming data and if it is detected as lamp data, it is processed immediately into arrays of shift register data for sending to the slaves. Each data byte takes up to 85μs to process and, at 38,400 baud, can arrive once every 260μs. Each byte received consists of 10 bits including the start and stop bits. The timer fires every 128μs and is used to increment a counter, so each mains half-cycle is split into 78 divisions. In the main loop, the software checks if the incoming AC waveform has flipped polarity and uses an December 2021  63 internal counter to mark that point with respect to the counter. Compensation is made for the fact that the pin does not change state precisely at the zero crossing; the pin transition voltage level is above 0V and varies depending on whether it is positive-going or negative-going. The microcontroller sets a second counter to provide a signal synchronised with each mains half-cycle. Checking the AC waveform and adjusting the counters can take up to 7μs, which is not a significant amount of time compared to the other activities that occur. Starting at the 20th (of 78) points in the cycle, the shift register bitmaps are fed to the output in turn. These 78 points are chosen to partially compensate for the instantaneous mains voltage varying over the cycle, resulting in a smoother brightness ramp. There is no setting that will give perfectly linear results for all incandescent globes, and LEDs will naturally not be affected in the same way, but the chosen numbers should give a good middle ground for all lamp types. The points are closer together near the peak and further apart near the zero crossing, which has the added benefit of diminishing the effects of jitter on the slave Triacs switching off. Scope 1 shows the timing of these data bursts. The green line is the output of the transformer, not the mains waveform itself, hence is it far from sinusoidal. Delivering this data takes around 75μs. So in the worst case of a data byte being received simultaneously with an SPI transmission, the timer could be delayed slightly. If this delay is ever longer than a 128μs timer cycle, timer counts will be missed. However, output waveform corruption due to missed timer events should not occur under normal operation, although small amounts of jitter (up to about 50μs) might occur under the very worst conditions. Note that the Translator has been programmed to only work on 50Hz mains systems. The timing is probably too tight for it to work properly on 60Hz systems. Status indicator LED Every timer cycle also triggers a check to update the status LED. Every two seconds, the AC waveform, incoming data and outgoing chain are checked. If a fault is detected, the LED flashes; otherwise, it remains solidly lit. One flash indicates that no incoming data has been received in the preceding two seconds. If you see two flashes, no downstream chain sense resistors have been detected. Three flashes let you know that no transitions have been seen in the AC waveform. Performing these checks and updating the LED state can take up to 15μs. Construction The Translator is built on a PCB coded 16110206 which measures 79mm x 45mm – see Fig.2. This fits neatly into a UB5 Jiffy box. Start by fitting and soldering the resistors as marked on the PCB silkscreen. Use a multimeter to doublecheck the resistance of each part before mounting it. Note that the resistors along the right-hand side of the board appear to be arranged in pairs, but some are not! The sole diode is next to CON1 at the bottom left of the PCB. Be sure to match the cathode mark to the silkscreen. Then fit the two 100nF capacitors, one adjacent to IC1 and one near OPTO1. Bridge rectifier BR1 is at the bottom centre of the PCB. You should ensure that its + mark goes to its bottom left, as shown on the silkscreen. Push it down against the PCB before soldering, then trim all its leads close to the PCB. Solder the two parts in DIL packages next, IC1 and OPTO1. There is room to use sockets if you wish, although Scope 1: the timing of the latch pulses relative to the mains waveform. The AC waveform is quite significantly distorted due to the properties of the transformer and the brief current inrush into the capacitor leading up to the waveform peaks. Still, it’s good enough to sense the zero crossings. The more closely-spaced pulses near mains peaks provide more even brightness steps for incandescent lights without affecting mains-powered LEDs too much. 64 Silicon Chip Australia’s electronics magazine siliconchip.com.au Fig.2: assembling the PCB is relatively straightforward; fit the parts as shown here, paying particular attention to the orientations of IC1, OPTO1, the electrolytic capacitors, diode D1 and the LEDs. If you experience issues due to control tones affecting timing, then a small value capacitor (10pf) between pins 6 and 14 of IC1 may help. there is little need for this as IC1 can be programmed in-circuit via CON4, even after it is soldered in place. Ensure OPTO1 and IC1 are orientated correctly, with their number 1 pins to the upper left of the PCB. Straighten the leads to allow them to be inserted, then tack two leads and ensure the parts are flat against the board before soldering the remaining leads. To install REG1, bend its leads back 90° around 7mm from the regulator body. Thread them through the PCB and fit one of the machine screws from the back of the PCB, then secure the regulator with the nut and washer on the front of the tab. Carefully align the regulator to be square within its footprint and tighten the nut firmly, but taking care not to twist the part. When you are happy with this, solder the leads from the back of the PCB and trim the excess. Fit REG2, making sure that it matches the outline on the silkscreen. Push down firmly and solder the leads. Mount the three electrolytic capacitors next, observing the polarity markings; all three have their positive lead closest to CON2 on the right of the PCB. Now fit the barrel socket at CON3. It may require some extra heat and solder to secure the larger tabs. You should also try to keep the part parallel to the Parts List – Digital Lighting Translator 1 double-sided PCB coded 16110206, 79mm x 45mm 1 9V AC plugpack with 2.1mm inner diameter barrel plug 2 PCB-mount RJ45 sockets (CON1, CON2) [Altronics P1448] 1 2.1mm inner diameter PCB-mount barrel socket (CON3) 1 5-way male pin header (CON4; optional, for programming IC1 in-circuit) 1 UB5 Jiffy box 4 M3 x 12mm tapped spacers 9 M3 x 6mm machine screws 1 M3 nut and washer (for REG1) 4 self-adhesive rubber feet Semiconductors 1 PIC16F1705 or PIC16LF1705 microcontroller, DIP-16, programmed with 1611020F.HEX (IC1) 1 W02M/W04M bridge rectifier (BR1) [Jaycar ZR1304] 1 6N137 optoisolator, DIP-8 (OPTO1) 1 7806 6V linear regulator, TO-220 (REG1) 1 MCP1700-3.3 low-dropout 3.3V linear regulator, TO-92 (REG2) 1 green 3mm LED (LED1) 1 red 3mm LED (LED2) 1 yellow 3mm LED (LED3) Altronics kit will be available 1 1N4148 signal diode (D1) Altronics has announced that they will be Capacitors making a kit for this project, code K5888. 3 100μF 25V electrolytic 2 100nF 63V MKT Resistors (all 1/4W axial 1% metal film) 1 1MW 5 10kW 4 1kW 1 220W 4 100W 1 10W siliconchip.com.au Australia’s electronics magazine edge of the PCB for neatness. If you wish to fit an ICSP header for programming IC1, you should use a straight (rather than right-angled) header. This can be left in place without fouling the box if it is mounted vertically. It can be mounted under or on top of the PCB as there is around 12mm of clearance on both sides. We recommend placing it underneath, as you might find that the adjacent capacitor prevents the programmer from being fully inserted onto the header from above. Next, solder the two RJ45 sockets, CON1 and CON2. They have clips to lock them in place, but it’s still a good idea to solder one lead and check that they are flat against the PCB and parallel to its edge before soldering the remaining leads. The only remaining components are the LEDs. If you wish to fit them now, leave 10-12mm from the top of their flanges to the PCB so that they sit just behind the front panel. However, it is better to leave them out until you can confirm their positioning against the assembled enclosure. Note that LED1 is green (data), LED2 is red (power) and LED3 is yellow (status). Programming IC1 Now is a good time to program microcontroller IC1 if this is required. If you buy the microcontroller from the Silicon Chip Online Shop, it will already be programmed, and you can skip this step. You can use a PICkit 3, PICkit 4 or Snap programmer. If you don’t have a programming application, we recommend using the MPLAB X IPE, which can be downloaded for free from Microchip’s website. Connect the programmer to CON4, December 2021  65 Fig.3: you might find that your UB5 Jiffy box already has small divots in the base to mark the four holes to be drilled. The side cuts start from the top of the box, so they can easily be made with a hacksaw or similar. Fig.4: before applying this panel artwork to the lid of your Translator, you can also use it as a template to mark the LED hole positions. Since the input and output connections are via identical RJ45 sockets, the panel label is a handy guide to making sure you don’t mix them up. 66 Silicon Chip Australia’s electronics magazine aligning the arrow on the programmer with the arrow on the PCB, both of which mark pin 1. From the IPE, choose the PIC16F1705 from the Parts list (or the LF version if you’re using that) and then click Connect. Browse to the HEX file, open it, then click the Program button and ensure that the “Program/Verify Complete” message appears. If you have already fitted the LEDs, the red LED should illuminate, indicating the presence of power, and the yellow LED should light up or flash after about a second. The green LED will do nothing until a signal is provided at CON1. Enclosure The PCB mounts in the bottom of a UB5 Jiffy box. If you want to test the Translator, we recommend drilling the top first, as you can use this to fit and align the LEDs. Fig.3 shows the drilling and cutting that is needed to complete the Translator. Three 3mm holes are needed for the LEDs. You can also download and print (or photocopy) our lid artwork (Fig.4) and use this to position the holes for the LEDs. We have a helpful guide to preparing panels: siliconchip. com.au/Help/FrontPanels Drill these holes as shown and then you can attach the panel artwork. If you haven’t fitted the LEDs, insert them into their respective holes and rest the lid over the top. By holding the lid against the tops of the RJ45 sockets and aligning the PCB to be centred on the lid, you can adjust the LED positions so that they fit nicely. They can then be soldered in place and their leads trimmed. This method has the advantage of compensating for any drilling inaccuracies. You can then remove the lid and siliconchip.com.au test the PCB. The drilling and cutting for the base looks a bit more elaborate but is not too involved. The Jiffy boxes that we are using have small divots at exactly the marked locations in the base of the box, so these are easy to align if your box has them. These are 3mm holes to suit the M3 machine screws. Mount the tapped spacers inside the base of the box using four screws. The square cutouts in the ends of the box are for the RJ45 sockets. Mark these with a pencil and use a hacksaw to make the vertical cuts. Score the horizontal cut with a sharp knife, and you should be able to gently flex and then snap the tab out with combination pliers. Check the fit of the sockets and use a file to open up the holes and tidy them if needed. The RJ45 sockets should sit level with the top of the base of the box. The final hole is for the barrel jack. We’ve indicated a 10mm hole to suit the plug we are using, but you should check that you don’t need a differentlysized hole to suit the plug’s body. This hole is best drilled by starting with a smaller ‘pilot’ bit, allowing you to check that the hole is aligned correctly before being enlarged. Make increasingly larger holes with larger bits, or use a step drill or tapered reamer to open the hole out further, then attach the PCB to the spacers using the remaining four screws. Completion It’s a good idea to run some final tests before closing it all up. Apply power via the barrel jack. The red power LED should light up, and you should be able to measure voltages relative to ground at REG1’s tab. Lead/pin 3 (closest to IC1) should measure close to 6V, while lead 1 will be around 12V for a 9VAC input. The 3.3V rail is best checked at IC1’s pin 1 (closest to the edge of the PCB). If these voltages are out by much, check around the bridge rectifier, capacitors and regulator, particularly for reversed parts. Yellow LED3 should be flashing once or twice every two seconds; any flashing pattern indicates that the micro is operating. If it is flashing three times, it is not detecting the AC phase correctly. If any ribs on the lid prevent it from sitting down flat against the RJ45 sockets, these can be removed by carefully cutting or filing them away. Align the lid to the LEDs and secure the lid with the screws included with the Jiffy box. Then apply the rubber feet to avoid damage from the screws on the bottom of the box. REAL VALUE AT $19.50 * PLU S P&P Using it Connect the CON1 “Data in” socket to any of the master units described in the October, November and December 2020 articles. These can be as simple as an Arduino board with two wires of half of an Ethernet cable wired to their headers (see photo below). Back then, we also presented a small PCB that can be attached to a CP2102 USB-serial adaptor, allowing a computer to act as a Master. It can be controlled using our Processing program. Some serial terminal programs may also be able to generate data for testing. Take care not to mix up the two connectors on the Translator. Doing so probably won’t cause damage, but it definitely won’t work. The green LED will flicker when the Translator receives data, indicating it’s probably wired up correctly. If all is well, connect any of the slaves described in the October 2010 or October 2011 issues to the CON2 “Data out” port. If you are only using LED slaves, then it is possible to run the Translator from a DC supply; in this case, we recommend a 9-12V DC plugpack. Note that the yellow LED will flash to indicate a fault with a missing AC waveform, but the Translator will continue to produce control signals. The Translator only translates the first 32 channels from CON1, so if you are using a mix of newer and older slaves, set the addressing switches on the newer slaves to the 33-64 range to make the best use of the available SC address space. An Ethernet cable terminated with jumper wires turns an Arduino into a Flexible Lighting Controller Master. siliconchip.com.au Silicon Chip Binders Australia’s electronics magazine Are your copies of SILICON CHIP getting damaged or dog-eared just lying around in a cupboard or on a shelf? Can you quickly find a particular issue that you need to refer to? Keep your copies safe, secure and always available with these handy binders These binders will protect your copies of SILICON CHIP. They feature heavy-board covers, hold 12 issues & will look great on your bookshelf. H 80mm internal width H SILICON CHIP logo printed in gold-coloured lettering on spine & cover Silicon Chip Publications PO Box 139 Collaroy Beach 2097 Order online from www. siliconchip.com.au/Shop/4 or call (02) 9939 3295 and quote your credit card number. *See website for delivery prices. December 2021  67 SERVICEMAN’S LOG A mixed bag of odds, sods, ends and bobs Dave Thompson It’s sometimes a bit of a curse when people around the neighbourhood discover that I can do repairs on electronics and anything else vaguely related. I’ve had my fair share of food processors, heaters, amplifiers and CD players turn up just through word-of-mouth referrals. Don’t get me wrong; I welcome anything as a challenge. However, while sometimes the results are positive, that isn’t always the case. Recently, I had an 80s-era Phillips CD player through the workshop. This thing was likely audiophile quality back in the day, and the price tag (still stuck to the top) confirmed that at $3500 Kiwi bucks, you’d have to be a serious audio guy to buy it. I don’t think – aside from a house or a car – I’ve ever paid that much money for anything! Some of my old audio gear and guitars were getting up there in price, but 3.5 big ones for a CD player? Not for me! Anyway, this player had a problem. It would no longer open, and I got the impression the owner was more interested in getting the CD out of it than an actual repair. As with most older devices, getting any spares for it – like another CD player module – would be problematic. I told him what I tell most people in this situation: I’d open it up and have a look, and if I can do 68 Silicon Chip anything with it, I will; but if I can’t, well, that’s all there is to it. The machine was built like an external masonry water closet. Where one screw would suffice, they used three. All the plastic parts were also clipped onto the steel chassis. They certainly knew how to make stuff back then! None of this glue-the-two-halvestogether and throw-it-away-if-something-goes-wrong business. One thing they didn’t do was round off the stamped chassis edges. Not only was this unit really heavy but the exposed metal edges were like guillotines. As I’ve been caught before, slicing my hands open on poorly-finished metal fittings, I knew this time to be extremely careful how I handled it. I once picked up a heavy amplifier case and the sharp-edged chassis cut into all my middle knuckles. I couldn’t hold anything for weeks, which is a major pain in the rear (among other body parts). Lesson learned! I disassembled this CD player and when I got inside it, I discovered that the CD module was like nothing I’d seen before. I was hoping that it would at least be similar to the modern-day units you get for computers, DVD players and stereos, but no, it was completely different. Even the connections to it looked proprietary. Although the module was clearly labelled with part numbers, as usual, I couldn’t find any relatable information on the web about it; no service manuals or circuits for it anywhere. I also searched the likes of eBay and other auction sites to no avail. I went back to the Australia’s electronics magazine machine and looked to see if I could pinpoint what was actually going on with it. On power-up, the CD player just sat there hunting, as if looking for a disc. It wouldn’t open as it was working, and that’s all it did. Disc in or not, it just sat there looking. I suspected the laser had failed, and that’s what the rest of it was waiting for – the laser to report a disc was present, then it could complete booting and carry on. I have dozens of laser modules removed from CD and DVD drives; perhaps I could adapt one of these to this drive? Once again, it was all so different, and the laser module itself was a heavy-duty thing that looked like even a hammer wouldn’t touch it. I couldn’t even see the laser diode as it was embedded well inside the carrier. I could possibly get the old one out, but only using drills and such, so that wasn’t going to fly. Part of being a service or repair guy is knowing when to pull the pin on a job, and for me, this was that point. I had the disc out; all I had to do was manually turn the drive door pulley while there was no power present, opening the drawer bit by bit until I could move it all the way out. I reassembled the thing and, against all hope, tried it again, just in case the drawer would open and the thing would magically work. But no, it was, as far as I was concerned, end-of-life. I suggested to the owner that he might get more success from an established repair agent, who might have spares that would get it working, but he agreed that it had its day and it was time for a new one. At least I got the disc out of it. The next odd job Another neighbour arrived out of siliconchip.com.au Items Covered This Month • A mixed bag of odds, sods, • • ends and bobs Fixing the motor in a burnt-out clothes dryer A Kriesler radio and its capacitor firework *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz the blue and asked if I knew anything about trailer lights. He’d recently had his trailer refurbished, with new incandescent taillights and an LED number-plate light and some of the cabling replaced. But some of those lights had already stopped working properly. Could I take a look? I suggested he should take it back to the people who’d refurbished it, but he said he already had several times, and they couldn’t find a fault in their work and weren’t prepared to spend any more time on it. I thought that was a bit rich, but the guy was clearly troubled by it, so I said I’d have a look over it and see what I could do. This was a standard trailer; nothing flash, just the sort of thing you’d fill up with rubbish or soil of a weekend and do a garden or dump run or similar. The lights and lenses all looked relatively new, as expected, but when hooked up to his car, he had no tail lights, and a brand-new LED numberplate light also didn’t work. The indicators did work, so that was something. The first thing I did was hook the trailer up to our own car; I wanted to rule out problems with his car’s fuses, power leads and trailer plug. Even though they are pretty hardy, trailer plugs can get a real hammering, and people can accidentally drop the trailer hitch onto the plug when moving the thing around, crushing it between the hitch and the road. However, once hooked up to our car, I got the same result as he did, indicating some kind of fault in the trailer wiring itself. This isn’t exactly rocket surgery; it’s basically a big tow-able wheelbarrow, but the inclusion of a wiring loom apparently elevates it to another level. In New Zealand, we use a heavyduty plug with seven contacts, and this plug hooks into a handy socket mounted on the car once the trailer is connected. I imagine it is the same connector used worldwide, but I don’t know for sure. Once connected, the indicators, brake lights and any other ancillary lights hooked into the system should ideally mirror the actions of the various rear lights on the car. My first step was to measure the voltages from the car’s socket and check that no shorts or high-­resistance joints were dropping the voltage. When I turned the lights or indicators on, or applied the brakes, I read the expected 12V (or near as reasonable) at all the correct pins. While colours for trailer wiring are supposed to be standardised, and most trailers are wired up correctly, there are plenty out there – perhaps built before the standards came in – with non-standard cabling. The wiring on this particular trailer was not standard, which made things a bit trickier. But due to the open nature of the plugs and sockets, one can readily deduce what coloured wire connects to what part of the circuit. And there’s another problem; ringing out a trailer loom with one person is tricky; I don’t have a three-metre arm span, nor do I have one of those tools for measuring connectivity in longer wiring looms. I ended up just using a small jumper lead with alligator clips at each end and connected one clip to a good clean spot on the trailer chassis and the other clip to each pin in turn at the connector end. I then used my multimeter with the buzzer function set to ALSO AVAILABLE 10% OFF YOUR NEXT DECEMBER ORDER WITH DISCOUNT CODE SCDEC10 FREE SHIPPING AUSTRALIA WIDE siliconchip.com.au THE TOOLS TO BUILD THE FUTURE w w w. p h i p p s e l e c t r o n i c s . co m Australia’s electronics magazine December 2021  69 span the ground and ‘live’ connections at the other end. It’s a bit of a faff walking backwards and forwards to set the clips, but with only seven big pins, it’s easy enough to do. I got identical results to the car-plugged-in tests, as expected. I took the non-working incandescent bulbs out of their sockets and tested them with the meter as well – all were fine, but I wanted to be thorough. Too many times, I’ve jumped the gun and had to backtrack over some silly missed problem like a blown light globe. Chasing a cable fault It appeared there was a lack of connectivity somewhere along the loom that connects the trailer socket to the lamps. The question was where. Two cables made up the loom on this trailer; both ran down a natural channel formed under the right-hand chassis rail before splitting at the right-rear light, and a single cable ran across the rear underside of the trailer and up to the left-hand light. Both were four-wire cables about the size of a standard mains lead and were strapped – some very tightly – using cable ties both together and to the chassis rails. Detecting breaks in longer cables is a bit of an art in itself, and while there are many methods using special tools and Wheatstone bridge-based machines and the like, I checked them using a ‘quick and dirty’ method. Using the jumper cable and multimeter once again, I connected one of my many dental picks to the non-grounded multimeter lead. I could then simply pierce the cable insulation and measure continuity along the length of the main cables, shifting the ground lead as I went along the loom. There’s a certain amount of educated guessing as to where the wires run within the insulation, and one could argue it exposes the inner wires to the elements. Still, the pick is so fine, and most trailer connections are exposed to the weather anyway, I didn’t see it as a problem. The main problem is the dental pick is dangerously sharp, so I had to take care not to miss the cable and find my fingers! At one of the tight cable tie points, I lost connection with the white wire in the bundle. This wire was terminated at the right-rear lamp, where it was split off using one of those plastic-coated inline crimp connectors to one wire leading to the LED number plate light. There was another similar connector for the second LED wire. That could explain why this wasn’t going either. That whole rear section of the loom was covered in 70 Silicon Chip poorly-­applied insulation tape, which I consider unsuitable for wiring sitting out in the weather. I’d have to re-do all that once I worked my way down there. I clipped the cable ties all along the loom down to the section where I thought it might be broken and marked that area with a bit of tape to avoid losing my place. I removed the cables from the right-rear light assembly and pulled them back through the chassis rail so I could easily get to the dodgy section. This would also make it easier to add proper heatshrink tubing where needed eventually. I was a bit surprised to find that the wiring simply enters the body of the taillights through a largeish hole in the backplate. In my opinion, this is a design flaw; as the lights hang directly behind the wheels, they can fill up with water and road grime flung up from the tyre through that hole. Now for the tricky part, peeling away the insulation around the fault. I didn’t want to replace the whole loom from front to back but would do so if push came to shove. I’ve in-lined joints before, and that shouldn’t be too much of a problem on a low-voltage system. I carefully split the insulation on either side of the suspected fault with the tip of a craft knife about 5cm along the ‘grain’ of the cable, being very careful not to carve anything else inside. Now having access to the crushed section, I could move the other three wires out of the way and check the white wire. I simply pulled on it a little, and a small section of insulation stretched, telling me the wire inside had parted company. I snipped it at that point and, sure enough, cut only through the plastic. Of course, if I stripped back the insulation and simply re-soldered this wire together, it would be shorter than the others, creating a messy join. Instead, I stripped it back on each side and installed some heatshrink tubing before using a brass ferrule to make up the length difference. A thorough crimp had it back to size without a lot of bulk, and after shrinking the tubing over the ferrule with a heat gun, I fed suitable large-sized self-amalgamating heatshrink tape down to cover that area of the loom. Once again, the heat gun had the tube down to size, and the amalgamation would see it well-sealed in there. Almost there With that area done, I went back to the rear end. I fed the loom roughly back into place and reconnected everything back to the light assembly. I wanted to test it before I went any further. This time, when it was all plugged in, I got brake lights and tail lights but, frustratingly, still no number plate light. Looking at the mess of how it had been connected into the loom, there was no wonder. Once again, I got the multimeter out, and while I had voltage to the point of the connectors that split the loom off to the LED, I got nothing after them. Hopefully, all I’d need to do is replace those inline connectors to get it working because the LED assembly had been riveted to the tailgate, and I didn’t want to have to drill those big rivets out. They had already cracked the plastic housing and I was reluctant to cause any more trauma to it. The people who had installed the LED had left plenty of cable length, so chopping out the connectors wouldn’t be a problem. I soldered those wires back together (after Australia’s electronics magazine siliconchip.com.au installing suitable heatshrink) and, when tested, it all worked properly. I then took the loom back out and fitted more heatshrink tape – all this would tidy up that insulation-tape mess. Now when everything was reconnected and appropriately cable-tied, the lights worked a treat, and the wiring installation looked a whole lot better. Job done! I wonder why the original installers couldn’t figure it out. You don’t have to be Wile E. Coyote, super-genius... Fixing the motor in a burnt-out clothes dryer A. L. S., of Turramurra, NSW had to take a guess at what had failed so he could order a replacement part before he’d disassembled the failed unit. His guess was close enough to result in a successful repair... Returning home one day, my wife came running out to greet me with “there’s been a disaster!” Our 5kg Simpson clothes dryer (39S500M) had stopped working and had emitted clouds of smoke, setting off the smoke alarm and filling the house with an evil smell! The smell from this dead dryer was slightly different from the usual burnt-out transformer smell that I was familiar with. It had the odour of a stale ashtray. My wife said it smelled like a car had done a burnout in the house, but I put it all down to the type of insulation enamel. My wife thought it was best to throw the dryer away because it was over 20 years old, and I agreed. But when I checked out the reviews of the newer high-tech programmable model, several reviewers gave it only two stars, and a couple of buyers regretted buying it. That’s because it has a sensor that is supposed to detect lower humidity and shuts down the “program” when it sees fit. The problem is that if the user disagrees with the decision of the dryer, they can’t dry the clothes for five or ten minutes more if the items are still damp! My wife also preferred the old-fashion timer and was very adept at setting the timer for various items. So I suggested that I have a go at fixing it because I was sure it was a burnt-out motor, and there were plenty of second-hand and re-conditioned replacements available online at reasonable prices. I could also find plenty of siliconchip.com.au Australia’s electronics magazine December 2021  71 other replacement parts such as drive belts, timers and odds and sods, which made me think that this model was infinitely repairable! She agreed but did not want me to pull it apart yet to avoid a mess in the laundry. So I took a gamble and bought what looked like a pretty good used motor (part #0214377106) for $69 online, which arrived after about two weeks. I tested it on the bench with a temporary AC mains supply, and it seemed very strong and noiseless, so it was time to operate and replace the faulty one. Before I could remove and dismantle the dryer, the kindly next-door neighbour (who enjoys working out at the local gym) helped me pull it off the wall. I then set about removing the screws from the back panel and took off the small nut which held the drying drum in place. Inside, I found three connectors: one for the incoming mains, one for the motor, and one for the heating element. These are tricky because they are hard to access; the sheet metal was really sharp, and my wrists were in danger of being slashed. It didn’t help that the wires were very short, and there was a narrow gap between the connectors and the edges of the back panel. I used thick leather gloves to help separate them, and then I could remove the back panel. I then removed the drive belt from the motor assembly and extracted the big drying drum for cleaning and inspection. The guts were full of dust and lint, so I vacuumed it out to see where all the screws were. I could just see some burnt lint around the motor capacitor. I used a 6.5mm socket on an extended shaft to remove all the screws holding the motor in place. The fan and shrouding had to be unbolted at the same time. Finally, it all came out, and I was able to see that the capacitor which was bolted to the motor had a cavernous hole (which was definitely not an inspection hole), and it had oozed molten metal all over the motor. The 8μF 450VAC rated capacitor had overheated and spilt its guts (shown below)! That explained the smell; a burning capacitor smells different to burnt windings. There was a thermal cutout, but this was mounted beside the motor on a piece of tin. Since the motor itself had not overheated, the full mains voltage remained active across the capacitor. Luckily, my wife had switched it off as soon as the smoke alarm activated; otherwise, it could have started a fire. Fortunately, the new second-hand motor was identical to the old one and also had the 8μF 450V capacitor attached, which looked very fresh. So I replaced both the motor and capacitor. Before everything could be reassembled, I filled a bucket with the lint I removed! My wife is very particular and empties the external filter assembly before every drying cycle. Obviously, that was not enough to prevent a huge buildup over 20 years. Perhaps this contributed to the demise of the This 8μF capacitor had overheated and leaked all over the motor. 72 Silicon Chip Australia’s electronics magazine motor capacitor; the rear ventilation slots were blocked, so there was no air cooling. Cleaning it up took me quite a few hours; I had to use a hose to wash the separated parts, allow them to dry and then reassemble them carefully. The motor bolted into place easily enough, and I threaded the belt arrangement by holding the tensioning spring back. You need to settle the belt onto the drum by rotating the motor by hand for at least two drum rotations before applying power; otherwise, it will instantly throw it off. Satisfied that all was good, I plugged in the repaired dryer, stood well back and set it going. It operated noiselessly and smoothly, and my wife and I watched it for a few minutes just like a new TV set. We were very happy that we had saved a few hundred bucks getting our dryer back in action! A Kriesler radio and its aluminium capacitor firework R. M., of Scotsdale, WA heard a knock at the door, and it was his mate Kevin, holding something that looked like a spent firecracker. It wasn’t, though... “I got this really good looking old radiogram, got it working, and it suddenly went bang! And I found this inside!” said Kevin. It did look a lot like a demised firework. About 12mm in diameter and 50mm long, tightly wrapped paper and foil, with one end showing definite signs of having exploded. When I realised the foil was aluminium, it clicked. I was holding the guts of an old high-voltage electrolytic capacitor. Having been retired for years, it had objected to suddenly being hit with volts and responded appropriately. A bit of leakage current, a buildup of heat and pressure, and bang’s your uncle. I offered to take a look at the radio, and it shows up the next day. It was a nice looking unit, a classic mid-20thcentury Kriesler in excellent condition. Someone had been taking very good care of it – I caught a whiff of furniture polish. Lifting up the lid, there was the large glass dial with an imposing array of knobs, and a record changer in a recess to the left. The cabinet was OK, but the innards might not match. Removing the Masonite back and a couple of long screws loosened the top part of the siliconchip.com.au deck, the dial swung up and released the chassis. I wriggled it out and onto the bench. I’d forgotten how heavy these things were! The top looked clean with no apparent damage, but underneath was another story... Within the usual tangle of pointto-point wiring, there was the empty aluminium can of an axial electrolytic. The end cap had been blasted away and hung forlornly from its solder tag. The once-liquid part of the contents was a grey goo sprayed all over the inside of the chassis. Luckily, it was facing away from most of the circuitry and expended its venom into a basically unpopulated corner. One thing that had copped the lot was the red active mains power lead. The rubber insulation had decomposed over the years, and it was stripped bare. The only reason it wasn’t shorting was that it was reasonably stiff and well-anchored. With judicious use of compressed air and a toothbrush, the chassis cleaned up nicely. All the rest of the circuitry looked good. I decided to make some quick checks to see if it was safe to proceed. I plugged it into a Variac and cautiously upped the volts. No smoke appeared, and the dial lights and all the six valve filaments lit up. I managed to connect one speaker and got a lot of hum, but also recognisable audio. One pleasant surprise was a copy of the circuit diagram stuck to the back panel. It was a bit faded and discoloured. Editor’s note: we have supplied another scanned version of this circuit. There were four filter caps on the high-voltage lines with their values clearly marked. 32μF, 50μF, 16μF and 8μF. The local electronic suppliers didn’t stock caps rated at 400V, but element14 did, so I ordered all four online. Next, it was time to replace that damaged power lead. Kev had thoughtfully looped up the slack lead and secured it with a cable tie. It seemed a bit long, and the plug looked modern, as did that end of the cable. I cut the tie and unwound the full length of the power cord, or should I say cords. The old cord was joined to a new one by a suspicious large insulation-tape-­ covered bump. Taking off the tape revealed a terminal block with just two joiners: Active and Neutral. There was no Earth connection because the extra length of cable was twin flex, with a three-pin plug but no green/yellow striped wire! This resulted in Kevin receiving a stern lecture on electrical safety. With the new capacitors fitted, it was time for the big test. I switched it on and wait for the old electronics to build up steam, then I got a glorious burst of ABC radio. I thought I’d better check the record player next. The complicated autochanger mechanism looked clean, and the bits moved freely, so I dug out an old 78 RPM disc and put that on the turntable. After lowering the pickup, there was a rush of snap, crackle and pop followed by music. But only through one speaker. I checked the balance control, but it was centred. Only one speaker was working now, but with the radio, both had given their best. An inspection of the ceramic cartridge told the tale – decomposing rubber again. The little flexible bridge that joins the stylus to the left and right piezoelectric elements had rotted badly and completely lost one leg. According to the label, the radiogram was made in 1965. What’s the chance of finding a new cartridge for that? Actually, it was easy; a bit of checking around and I found a replacement. It cost $70, but I now had two-channel mono. To make sure nothing else was going to blow up, I left the radio running for a day. There were no problems, so the nostalgia box went back to a happy Kev. The capacitors cost around $40, so for just over a hundred bucks, he was happily grooving along to the sweet sounds of his extensive collection of SC records. The circuit for the Kriesler 11-98 manufactured in 1965, scanned from Philip Leahy’s HRSA Circuit Book 5. siliconchip.com.au Australia’s electronics magazine December 2021  73 PRODUCT SHOWCASE New Keysight distributors in Australia Keysight Technologies has signed leading test and measurement companies, Rapid-Tech Equipment and Leda Electronics Pty Ltd as authorised distribution partners in Australia. The new distributors, owned by one company, cover all of Australia, improving customers’ access to Keysight’s line of test and measurement solutions, coupled with comprehensive local support and service. “Keysight is fully committed to supporting customers throughout Australia,” said Simon Rodger, Keysight’s Australia channel sales manager. “Adding Rapid-Tech and Leda Electronics to our network of distribution partners helps to ensure Australian customers receive the best solutions and technical expertise needed to be successful.” Rapid-Tech Equipment, headquartered in Melbourne, was started in 1996. The company has offices in Sydney, Brisbane, Perth and Adelaide, providing advice and high-quality test and measurement equipment to customers across eastern Australia. LEDA Electronics Pty Ltd is an established importer, distributor, wholesaler and retailer of quality test and measuring instruments in WA, operating for over 30 years. The company has a network of sub-­distributors throughout WA with technically qualified staff who provide customer service and calibration support. Keysight Technologies Aus. 745 Springvale Road, Mulgrave VIC 3170 Phone: 1800 629 485 tm_ap<at>keysight.com Mouser Electronics adds nearly 25,000 new parts In September, Mouser launched more than 24,740 products ready for shipment. Some of the products introduced by Mouser last month include: Maxim Integrated MAX32672 Arm Cortex-M4F Microcontrollers Maxim Integrated MAX32672 Mouser Electronics Inc. 1000 North Main St, Mansfield, TX 76063 USA Phone: (852) 3756 4700 www.mouser.com microcontrollers combine a flexible and versatile power management unit with a powerful Arm® Cortex®-M4 processor with a floating point unit (FPU). Futaba LC070HA TFT-LCD Module The Futaba LC070HA is a touchcontrollable display module designed for embedded applications. Renesas Electronics FS3000 Air Velocity Sensor Module Renesas FS3000 is a surface-mount module that provides precision air flow monitoring for detecting system failures, measuring air handling, controlling fan speed, and more. STMicroelectronics STEVALMKI210V2K iNEMO Inertial Module Kit STMicroelectronics STEVALMKI210V2K iNEMO Inertial Module Kit includes a main board and adapter board for evaluating the ISM330DHCX iNEMO inertial SiP module. To see more of the New Product Insider highlights, go to www.mouser. com/newproductinsider Study in your own time University of Southern Queensland are leaders in online education, offering students flexible degrees that allow them to study and continue living their life. Engineering degrees in electrical, electronic, computer systems and mechatronics are all available online, with graduates recognised for their industry-ready skills. Students undertake research and design projects – one example being the Mansell Infant Retrieval System, which incorporates advanced biomedical hardware and software. 2, 3 & 4-year degree courses are available, and recognition of prior knowledge may reduce that even further. Practical work is not neglected, as study is augmented with experimental work at home, intensive on-­ campus schools, simulation software and online video-based teaching. 74 Silicon Chip University of Southern QLD Phone: 1800 269 500 study<at>usq.edu.au www.usq.edu.au/engineering Australia’s electronics magazine siliconchip.com.au Multi-channel current/power monitors from Microchip The need for improved energy management in electronic systems is critical. Having the ability to measure and communicate power, voltage, current and energy accurately with minimal system power consumption is paramount for system performance and efficiency, form factor, low component count and reduced heat dissipation requirements. Microchip’s recently released PAC194X/195X multi-channel power monitor family with single-, dual-, triple- and quad-channel options is the latest addition. The PAC194X family incorporates the PAC1941-4 rated at 0-9V, while the PAC195X family has the PAC1951-4 rated at 0-32V. All of these devices have the capability to provide voltage, current, power and energy readings over their I2C-compatible bus. The PAC194X/195X family has been enhanced with two independent alert outputs for over-power, over/under voltage and current event detection. These ICs provide 16 bits of resolution for current and voltage monitoring and on-chip accumulation of power results for energy measurement. The PAC194X family focuses on portable applications monitoring up to 9V and the PAC195X family is targeted for applications requiring monitoring of voltage rails up to 32V. Both product families are well suited for portable applications, drones, secure communication, sensors, optical sights, smart base, data centers and any application utilising FPGA/SoC devices where power consumption and battery life are critical. The multi-channel PAC194X/195X family saves at least 31% of power usually consumed by two single-chip power monitoring devices and allows the flexibility to define, capture, warn and report dedicated events. The PAC194X can measure 9V directly with no additional circuitry and includes configuration for single-cell applications at 0 to 4.5V with the same 16 bits of resolution. F or eas e o f development, we offer evaluation Digi-Key launches new Scheme-it features Scheme-it is a cloud-based tool available to users globally for designing and sharing electronic circuit diagrams and schematics. The new features include: • Ultra Librarian symbol integration This feature brings in ~2 million of Ultra Librarian’s detailed symbols and images from Digi-Key’s product catalog. • Symbol Editor 2.0 A custom symbol editor that allows users to create new symbols that are not currently included in Scheme-it, offering endless ways to customise designs. • Mathematics markup Powered by LaTeX, users can now properly format and insert mathematical formulas and calculations directly on schematics. The Scheme-it tool includes a comprehensive electronic symbol library and an integrated Digi-Key component catalog that allows for a wide range of circuit designs. In Scheme-it, users can create a Bill of Materials (BOM) and purchase siliconchip.com.au components used in their projects, as well as share projects with others and export to KiCAD, PNG, SVG and PDF file formats. Schematics created in the platform can be shared publicly if desired and become searchable on the Scheme-it homepage, allowing for idea sharing and further innovation. A dedicated section on Digi-Key’s TechForum is also available for Scheme-it users to ask questions, make comments, and share ideas about the tool. (https://forum.digikey. com/c/design-tools-and-resources/ scheme-it/12) To use Digi-Key’s Scheme-it tool, visit the Scheme-it homepage at www. digikey.com.au/schemeit/home boards which connect to a PC via USB, and a Graphical User Interface (GUI) to display the data and the option to disconnect the PC and communicate directly to a different host controller. Why would you want to use these? • Lower risk • Reduced cost • Smaller footprint • Software drivers for Windows 10, MCC, Python, Linux (TBD) • Eliminates the need to code separately for high and low power consumption scenarios • Improved prototyping with higher sampling rate (burst mode) • Better event detection for system analysis • Eliminates the need for a filter circuit and external components More detail on this product line of multi-channel power monitors can be found below: www.microchip.com/ sitesearch/search/All/PAC19 Microchip Technology 2355 West Chandler Blvd, Chandler Arizona 85224-6199 USA Phone: (480) 792 7200 www.microchip.com Altronics Q0594 50A coulometer with shunt Altronics have added to their range a compact battery “fuel gauge” for monitoring how much capacity you have left in your remote power, auxiliary battery or electric powered transport. It provides voltage, current, power, real capacity and remaining run time. It suits any battery chemistry and voltage between 8V and 120V and includes a 50A shunt with sampling circuitry providing 0.1V resolution and 1% accuracy. Available now at Altronics for $89.90, catalog code Q0594 Digi-Key Electronics Altronics Thief River Falls Minnesota USA Phone: 1800 285 719 www.digikey.com 174 Roe St, Northbridge WA 6003 Phone: (08) 9428 2188 www.altronics.com.au Australia’s electronics magazine December 2021  75 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. Orrery (planetarium) using a Micromite LCD BackPack An orrery (or planetarium) is a model of the solar system showing the position and motion of the planets. The oldest known orrery (called the Antikythera mechanism) was discovered in a shipwreck in 1901 and is thought to be over 2000 years old. The first modern orrery was designed in 1704, with the Sun at the centre of the universe. This was presented to Charles Boyle, the 4th Earl of Orrery in 1704, and the term “orrery” was coined. You can find further information about the history and development of orreries at https://w.wiki/3qv6 Traditionally, orreries were mechanical, but this one is electronic, showing the position and motion of the planets on the Micromite’s colour touch screen. 76 Silicon Chip It operates in two modes. The first is similar to a mechanical orrery in that the position of the planets is advanced by one day every second. This shows the motion of the planets relative to each other, all revolving around the Sun with the Moon revolving around the Earth. Let’s call this demonstration mode. Real-time mode shows a display for any date and time from January 1st 1900 to any date in the future. Typically, the date and time will be set to the current date and time, but can be set to any date, for example, to find the position of the planets on the day you were born. The display then continues to be updated in real-time. There is also the option to display the phases of the Moon, the position of Australia’s electronics magazine the Sun relative to the tilt of the Earth and the rise and fall of the local tide. The Sun is represented by a small yellow circle in the centre of the display. Around the Sun are eight concentric circles representing the orbits of the eight planets, and the position of each planet is represented by either a letter or an astronomical symbol. A ring around the Earth represents the orbit of the Moon, and a dot the position of the Moon. Optionally, you can change the circles representing the orbits of the planets to ellipses. This makes better use of the width of the screen. The option to show or hide the phases of the Moon is in the top lefthand corner, the position of the Sun relative to the tilt of the Earth in the siliconchip.com.au top right-hand corner, and the height of the local tide in the bottom righthand corner. It can also show the time in addition to the date in the bottom left-hand corner. Note that the tide and time are only displayed in realtime mode. The display is updated once per second in demonstration mode. The display is updated each minute in real-time mode if the time and/or tide are displayed; otherwise, it is every hour. Mercury moves approximately 4.1° every 24 hours, Venus by 1.6° and the Moon by 13.4°. The tide graphic increases or decreases in height roughly every 9 minutes. You would be lucky to see the outer planets move – Neptune moves 1° every 167 days! All positions are relative to the Earth’s northern hemisphere winter solstice. Between screen updates, the Micromite clock speed is reduced to 20MHz to save power. Unfortunately, the touchscreen appears to become inoperative below 20MHz. Circuit description The circuit of the Orrery is basically identical to the Touchscreen Super Clock from July 2016 (siliconchip. com.au/Article/10004). That design was essentially a BackPack with a real-time clock module attached, and this one uses the same hardware. The only difference is that the Super Clock could optionally get its time from a GPS module, while the Orrery has no such option. The Micromite will use its built-in clock without the real-time module, but this can drift by a few seconds an hour. Also, without the real-time clock module, it will be necessary to set the date and time each time the Orrery is powered up. Of course, the software is different, and the BASIC source code is available for download from siliconchip.com. au/Shop/6/6051 When uploading the BASIC code, make sure your Micromite LCD BackPack’s touchscreen has been set up and touch calibrated as per the BackPack articles. Using it When the Micromite is powered up, it will immediately display the orrery. If the DS3231 module has been installed and previously initialised with the correct date and time, this will be shown in the bottom left-hand corner of the screen. Otherwise, the date and time will be set to the Micromite default of midnight on January 1st, 2000. Touching the LCD panel will display the setup screen with several options. “Set date” will display three additional screens with a numeric keypad to allow the correct date, time and then time zone to be entered. An incorrect entry can be corrected with the “Delete” key and the date or time saved with the “Save” key. If fitted, the DS3231 will be updated automatically. The “Show / Hide moon”, “Show / Hide time” and “Show / Hide earth” buttons switch on or off the displays in the corners of the screen. “Circle / Oval” switches between a circular or elliptical display, while “Text / Symbols” switches between alphabetic and astronomical symbols for the planets. Real-time or demonstration mode is selected with the “Real time / Fast mode” button. The “LCD xx%” button sets the brightness of the display, but this will only have any effect if you have version 2 or later of the Micromite BackPack and have installed the optional components for software control of the screen brightness. Otherwise, you can set the screen brightness via the trimpot on the Micromite PCB. The set tide button shows an additional screen that allows the time of the local high tide to be set and gives the option to show or hide the tide display. Note that over the long term, high tides occur every 12 hours and 25 minutes, but individual high and low tides can vary considerably, sometimes by up to an hour. As a result, the tide display should only be used as a rough guide. Local tide tables for your area should be readily available on the internet, and it is probably best to look at the pattern of high tides for your area and choose one that falls close to the average of 12 hours 25 minutes. The tide display is based on the local time that has been entered and is unaffected by the time zone setting, which only affects the position of the planets and Moon. The time of the local high tide will need to be adjusted if your area switches between winter and summer time/daylight savings time. Kenneth Horton, Woolston, UK. ($120) The Orrery screen can have the planet displayed by a letter or an astronomical symbol; the ring around the earth (‘E’) defines the orbit and location of the Moon. The tide display at lower right is based on the entered local time and is separate from the time zone setting which is used for the positions of planets and the Moon. siliconchip.com.au Australia’s electronics magazine December 2021  77 Non-contact cloud-based temperature sensor with speech To help track the health of the employees in our department, I have created this non-contact temperature sensor at the entry point. All you need to do is place your forehead close to it (within 2-5cm), and it measures your body temperature and plays back audio to indicate whether it is normal or high. It also uploads the data to a cloud server (www.thingspeak.com) for later analysis. It uses an HC-SR04 ultrasonic sensor to measure the distance to the person. Once that distance is close enough, it measures the temperature, plays back an audio file depending on the reading, then uploads the data to the internet. If it detects that someone is nearby, but not close enough (between 5cm and 78 Silicon Chip 15cm), it plays back an audio file asking them to approach closer. The ESP32 has two digital-to-analog (DAC) outputs at pins 9 & 10 (IO25/26). Audio playback in this case is from pin 9. One of two 8kHz PCM (pulse-code modulated) audio files is played back depending on whether the temperature measurement is below or above 37°C. A special Arduino library is used for this capability (XT_DAC_Audio from xtronical.com). A small 5V audio amplifier using the PAM8403 IC is used to deliver this sound to a 3W 8W loudspeaker. The ESP32’s WiFi capability is used to upload the temperature data to the cloud server at www.thingspeak.com The Arduino sketch to load onto Australia’s electronics magazine the ESP32 is available for download from siliconchip.com.au/Shop/6/6052 You will need to open a free account at www.thingspeak.com and modify the API key in the software to match the one you are supplied with before it will upload data. It supports multiple WiFi networks with separate SSIDs and passwords, so that whichever one is found will be used to transfer data to the cloud. You will need to modify the SSID and Password section of the sketch to contain your network details. The circuit uses two ESP32 modules; one is dedicated to handling the audio playback while the other monitors the temperature and distance sensors and drives the display. siliconchip.com.au The voice-handling module is programmed to play back one of the two sound files when pin 28 or 29 is brought high, and these pins have pulldown resistors to prevent audio playback at power-up or when the other micro is reset. The main ESP32 connects to the ILI9163 colour TFT display via an SPI serial bus, the HC-SR04 ultrasonic ranger via a two-pin digital interface and the MLX90614 IR temperature sensor via an I2C serial bus. As well as playing back the appropriate sound file, the unit also lights the red or green LED (red = high temperature, green = normal temperature), and it sounds the connected piezo buzzer if the temperature is high. Both the ESP32s may be powered from one 5V DC power supply. The audio data I have created is in the files “fever.h” and “ok.h”, while the file that is played when someone is not close enough for measurement is in “wel.h” (short for “welcome”). To change this, first record your desired audio to 8kHz, 16-bit WAV files. You then need to change these files to HEX format. There are many online sound converter sites such as www. fromtexttospeech.com that can do this. You then need to convert the HEX data to C code by using the software HxD from www.mh-nexus.de which produces a simple text file that you can use to replace “fever.h”, “ok.h” or “wel.h”. You can see the data recorded on my cloud server at www.thingspeak. com/channels/1371171 Besides showing the temperature readout on the screen, it also shows a letter code in the lower-left corner. C = Connected to WiFi, U = Data Uploaded, D = Distance measurement. Any form of ESP32, ESP32S or ESP32 S2 module will work for this project. Bera Somnath, Vindhyanagar, India. ($100) Editor’s note: while normal body temperature is generally considered to be 36.5-37°C, it is possible to measure above 37°C without being ill. Some people are simply hotter than others, and exertion and other factors can affect your core temperature to a certain extent. That time of year is nearly here... CHRISTMAS Spice up your festive season with eight LED decorations! Tiny LED Xmas Tree 54 x 41mm PCB SC5181 – $2.50 Tiny LED Cap 55 x 57mm PCB SC5687 – $3.00 Tiny LED Stocking 41 x 83mm PCB SC5688 – $3.00 Tiny LED Reindeer 91 x 98mm PCB SC5689 – $3.00 Tiny LED Bauble 52.5 x 45.5mm SC5690 – $3.00 Tiny LED Sleigh 80 x 92mm PCB SC5691 – $3.00 Tiny LED Star 57 x 54mm PCB SC5692 – $3.00 Tiny LED Cane 84 x 60mm PCB SC5693 – $3.00 We also sell a kit containing all required components for just $14 per board ➟ SC5579 siliconchip.com.au Australia’s electronics magazine December 2021  79 Switching cells between parallel and series Many Li-ion/LiPo charging modules are designed to handle either a single cell or multiple cells in parallel. That’s because they often run off 5V (eg, from a USB port or charger), and that’s ideal for linear charging of a single cell which ranges from about 3.3V when flat to 4.2V when fully charged. In many cases, you need two or three cells in series to get a high enough voltage to power a device. While it’s possible to generate higher voltages for charging multiple cells in series from 5V, that requires a more complex switch-mode boost converter, and they can generate EMI. When charging cells in series, you also need to consider how to keep their voltages balanced (equal). This circuit shows a much simpler solution. A single DPDT or 4PDT switch can be used to switch two or three cells between series and parallel connections, for powering a circuit and charging, respectively. When connected in parallel for charging, the cells are automatically balanced. To avoid the need to manually switch between charging mode and usage mode, a DPDT or 4PDT relay can be substituted for the switch, with the coil powered from the charging socket. A diode or similar can be used to ensure the coil cannot be energised by voltage back-fed from the battery. This way, the cells are automatically switched between the two modes. Use the relay’s NC contacts for the parallel connections (marked P) and NO contacts for the series connections (marked S). Benabadji Mohammed Salim, Oran, Algeria ($80) Editor’s note: while this should work in theory, we do not recommend this approach. That’s because any voltage imbalance which builds up in the cells as they discharge (due to differing cell capacities etc) will cause very high currents to flow as soon as the cells are switched into the parallel configuration. These currents could easily destroy or weld the switch/relay contacts. If you decide to use this configuration, we strongly recommend inserting PTC thermistors (or similar currentlimiting devices) into the connections between cells in the parallel configuration, switched out when the cells are connected in series. These can be connected inline where the red asterisks are shown. While adding such PTC thermistors will affect the rate at which the different cells charge, they should not affect the end-of-charge detection very much, so all cells should still charge fully (given enough time). The PTC thermistors should be chosen to have a ‘hold’ current rating that’s somewhat above the maximum charge current and a ‘trip’ current below the switch/ relay current rating for DC. Connecting two pushbuttons to an input-only pin Some PICs have a pin that can only be used as an input, eg, GP3/RA3 on the PIC10F200. In many cases, this is because that pin has other functions like MCLR. Sometimes you need to connect more devices to a micro than it has pins; many common techniques for making a pin dual-purpose require it to be switchable between being a digital input and output, which is not the case here. Other tricks use an internal ADC (analog-to-digital) converter with several external resistors connected as a divider to measure a different voltage generated by each pushbutton being pressed. For more on these techniques, see Microchip application note AN234 and Tips ‘n Tricks DS40040C. This simple circuit shows how the input-only GP3/RA3 can be used to 80 Silicon Chip sense two different pushbuttons being pressed, despite not being able to act as an output or an analog input. This relies on the pin having a selectable internal pull-up current, as is the case in both this chip and most of Microchip’s midrange family (the new XLP generation). According to their datasheets, the internal pull-up resistor has a typical value of about 23kW when Vdd = 5V. As GP3 is a TTL type input, we must choose a value for the external resistor so that when the internal pull-up is enabled, we have more than 2.4V as the idle voltage at GP3, giving an idle high-level state. This allows us to sense when S1 is pressed, as the pin will idle high but will go low when S1 is pressed. To sense a press of S2, the internal pull-up is periodically disabled. When we Australia’s electronics magazine disable the pull-up, the input will be pulled low by the 27-47kW resistor if S2 is not pressed or will be held high if it is pressed. The 1kW resistor avoids a short circuit between Vdd and Vss if both buttons are pressed simultaneously. Amine Houari, Oran, Algeria. ($70) siliconchip.com.au Festive Build It Yourself Electronics Centres® DEALS Bluetooth Boom Box & Wireless PA Need instant sound for your next big get together? y tech loving family. an r fo s ea id ft gi e lu Great va 31st. Sale ends December With outdoor sensors & smartphone app! Get live, local weather at home. Fire the weather man! This fantastic home weather station displays all your local weather data - great for boaties, gardeners & farmers. Bright & clear base station shows indoor/outdoor temperature, humidity, air pressure, rainfall, wind speed and direction. You can even connect it to your home wi-fi to monitor readings & data with your smartphone. 100m sensor range. With bea triggeredt LED lights ! Not only is this a great sounding boom box for your party music, it also includes a wireless microphone for speeches and karaoke! Offers up to 8 hours use from a single charge. You can even pair it with a second speaker using True Wireless Stereo (TWS) to really get the party pumping! You can even record your embarrasing 21st birthday speech to USB memory sticks. Size: 560H x 250D x 260Wmm. 219 $ C 5160 279 $ X 7063 SAVE $10 29 $ Say to goodbyein! eye stra SAVE $10 65 $ X 4204 3 Dioptre SAVE $10 70 $ X 4205 5 Dioptre “The most useful present i’ve ever received“ - Mark Edmonds Augusta, WA. Inspect-A-Gadget LED magnifier for micro tasks Why pay $300 for a MaggyLamp? The inspect-a-gadget illuminated desk magnifier is an absolute bargain $65, we believe ours is every bit as useful. An incredible visual aid for detailed inspection and work on fine items with full clarity through the lens. Tackle complex miniature tasks with confidence! X 4204 also fitted with 12 dioptre insert. X 3070 35 Acrobatic Mini Drone Nifty little copter for flying up to 30m - it even does acrobatic flips. Easy to charge at home or in the car with USB. ≈5 mins flying per charge. Requires 4xAAA batteries. Drone size: 75 x65 x 25mm. Ages 6+ Amazing Bluetooth Sound For Less! The perfect every day commuter earphones with top notch wireless sound, compact folding design and up to 18 hours of listening between recharges ideal for longer flights. Bluetooth 5.0. The must have summer pool toy SAVE $10 $ Create a pool panic with the RC shark. Controller doubles as a storage case. X 3098 With life like swimming motion and easy controls it’s a fun summer toy. Also great for the bath tub! USB rechargeable. 34cm long. Requires only 2xAAA batteries for the controller. Ages 6+ e With tyre smok al re r fo r to genera ! drifting effect SAVE $10 39.95 $ C 9034A SAVE 19% 64 $ Drift up a storm with the RC Drifter! X 3099 This amazing 360° spinning RC stunt car provides hours of drifting fun on carpet and hard surfaces. Control by hand genstures or traditional remote control. USB rechargeable. Ages 4+ Order online <at> altronics.com.au | Sale pricing ends December 31st. Tech gifts for less. Attach your camera anywhere! Got a TikTok’er ok! Great for vlogging & TikT in your house? Let them record videos anywhere with these handy flexible tripods for phones, GoPro cameras and small digital cameras. Easily stands on uneven surfaces and can be secured to a pole or railing. Reading Light USB C PD 80W mains output C 9021A 4 USB charging ports SAVE $30 109 $ Dual LED Torch SAVE $60 209 $ D 2213* 28cm SAVE 24% M 8197 30 $ D 2212* 16cm SAVE 28% Includes wireless remote. 25 $ Super Quiet Noise Cancelling Bluetooth® Headphones SAVE 50% 24.95 $ FANTASTIC VALUE AT $109! Why pay $300 or more? D 2327* Charge two phones at once with wireless charging. Suits iPhone and most Android. For fast charging you’ll also need a QC3.0 USB wall charger, such as M 8863 $20. Includes USB cable. 25 A 1112* 2 Channel Bluetooth USB Adaptor Provides wireless audio to TWO pairs of headphones at once! Ideal for two player gaming on Switch, PS4 or watching media on PC & Mac. Take high quality audio notes with ease! X 0705 79 $ *Devices shown for illustration purposes. The outdoor entertainer! Pump up the tunes around the BBQ or pool this summer with this nifty little speaker offering 3-4 hours listening time with Bluetooth 5.0 quality and range. Pairs to a second unit using True Wireless Stereo for even more sound! Water resistant design (IP65 rated). Brand name performance for less! Great for uni students! D 0515* USB & wireless charging in the one device. Stay charged up anywhere you go. 10,000mAh capacity. Includes charging cable. Dynalink® F2 Pro Gaming Headset Multi-platform ready! Suits PC, Playstation, Xbox and Switch with included TRRS adaptor. Offers excellent comfort for long gaming sessions with RGB lighting effects (when USB is plugged in). 2m cable. Record CD quality audio with excellent audio pick up for taking audio notes during lectures & recording interviews. 8GB on board memory with Micro SD slot. USB rechargeable. SAVE $20 99 $ 39.95 $ Portable Summer Tunes Dynalink® BT5.0 Can Speaker Wireless Charging Battery Bank $ HOT PRICE! D 2038 True wireless earbuds with the latest in active noise cancelling circuitry for immersive sound in noisy environments. Listen for up to 4 hours, then store them in the charging case - which even SAVE $20 has wireless charging! C 9040A Black C 9041A White HALF PRICE! This air travel friendly portable power generator is fitted with 6Ah battery bank, 80W 240V mains inverter, 18W power delivery USB C charger & QC3.0 USB charger. Offers you cable free power for both AC and DC appliances! Recharge by USB or included power adaptor. Minimise outside interference with world class noise reduction technology. Designed & engineered in Silicon Valley, USA. • Block out distractions while you work • Superb active noise cancelling • Bluetooth wireless • 12hrs of listening time. • USB rechargeable (includes cable) • Amazing sound. You be the judge - try a pair in store! Active Noise Cancelling Bluetooth® Earbuds Say goodbye to messy charging cables! Carry 240V Power Anywhere! SAVE $20 Bluetooth FM Audio/Hands Free Adapter With stylish RGB light! Transmits bluetooth audio from your phone (music, routes phone calls etc) to your cars FM radio. Plus it’s also a QC3.0 & USB C charger. SAVE 24% X 0604B 39 $ SAVE 27% 50 $ C 9042 Table Lamp With Wireless Charger A stylish glossy white table lamp with adjustable dimming, colour temperature & wireless charging. Great for the desk or bedside table. Powered by any USB wall charger - 2A minimum (M 8863 $19). SAVE 24% X 4221* 30 $ Order online <at> altronics.com.au | Sale pricing ends December 31st. A great bedside or study lamp 30 $ Build & have fun this Xmas. SAVE 25% 45 45 $ $ K 1095 Cute Scurrying Hedgehog Kit 3 In 1 All-Terrain Robot Kit 22 SAVE 28% Build it 4 ways! Learn coding! Have fun! K 1150 This cute hedgehog toy kit bristles his spines when he hears a loud noise (such as a hand clap). He will even curl up and roll away if you scare him! Assembles in <2 hours, no special tools required. Requires 4 x AAA batteries. Ages 8+ Great fun for the kids to build and play with! This single kit can be built (and re-built) three ways! Lifting capacity ≈100g. Wired remote control. Requires 4 x AA batteries. Ages 10+ $ Tobbie is back and he’s had an upgrade! Powered by the popular BBC micro:bit board, this version has unlimited scope for self programming. Front screen displays text & symbols. Great for teaching kids coding. Requires 4xAAA batteries & micro:bit board. Ages 8+ K 1152 Build it 3 ways! SAVE 25% K 1126 Tobbie II Hexapod Robot Kit SAVE 22% SAVE $9.95 50 Requires Z 6439A micro:bit ($27.95). $ SAVE 15% 28 $ K 1135 33 $ SAVE 22% K 1113 Build it 14 ways! Full Motion Robotic Arm & Claw Kit 14 Solar Kits In One! 4 in 1 Robotics Kit Air Powered Buggy Kit Assemble 4 robot designs which teach kids about geared movement in a fun way! Requires 1xAA battery. No soldering required. Ages 7+ Requires no batteries, electric motor or any conventional fuel to make it drive. Use the air pump to fill the bottle - let it go & watch it fly! Travels up to 50m. Ages 8+ 59 $ K 1107 A great introduction to basic robotics. Five motors allow base rotation, shoulder, elbow & wrist motion, plus claw for picking up objects (up to 100g). Includes wired controller (add USB PC control for $35 - K 1108A). Ages 9+ A fun and educational kit designed to assemble 14 different ways to inspire your kids to learn about solar power. No soldering required. Requires no batteries. Ages 8+ SAVE $10 39.95 $ TOP SELLER! K 1154 Build one robot up to 5 ways! SAVE $10 39 .95 $ K 1148 The Original Tobbie Robot Kit A six legged robot kit designed to avoid objects or follow you around the room. Easy to build. Requires 4 x AAA batteries. Ages 8+ 5 In 1 Smart ‘Coding’ Robot Kit Features a central coding ring which tells the robot directions and when to perform actions. Can be built and re-built 5 ways. Teaches kids about coding with no computers required! Requires 1xAAA battery. Ages 8+ K 1149 VALUE! Build it 12 ways! K 1141 VALUE! 49.95 39.95 $ $ 12 In 1 Solar & Hydraulic Kit A huge parts kit which can be built and rebuilt into 12 different solar powered designs. Hours of fun for kids aged 8 or over (or younger with adult help). Hydraulic Cyborg Hand Kit Build your own full size hydraulic powered robotic hand. Fits over your own hand like a glove and simulates joint movements to pick up objects. No batteries. Left & right handed. SAVE $10 39 $ SAVE $10 SAVE 18% 18 $ .50 49 $ SAVE 20% K 1138 Solar Powered Wild Boar Kit A basic solar DIY toy, it is ideal for a do-ityourself school holiday project with the bonus of being educational! Ages 6+ K 1139 19 $ .95 Solar Powered Rover Kit Build this fun 6 wheel all terrain vehicle modelled on famous NASA designs. No soldering or batteries required! Ages 8+ K 1097 K 1119 Build yourself an Aussie icon! Robot Frilled Neck Lizard Kit. Build it up and have it follow you like a pet. Or sneak up and surprise it, making it spread its frill. 37cm long. Requires 4xAAA. Ages 8+ Tribo 3 in 1 Coding Robot An easy to build and program robot which uses keypad entry commands to program movements and actions. No PC required! Uses 4xAAA batteries. Ages 8+. Order online <at> altronics.com.au | Sale pricing ends December 31st. Festive break essentials. SAVE $50 130W Remote Power Folding Solar Panel 199 $ M 8193 & USB Keeps devices charged with wireless Going bush? Have power wherever you go on your next 4WD/camping adventure. Includes 130W panel, solar regulator, battery connection cables and canvas carry case. 3 stage solar charger. Adjustable stand for best sun placement. 664x631x75mm (folded). charging! Portable Battery Bank Jump Starter An all round portable charging device - plus vehicle jump starter! Not just for car battery emergencies, this high capacity battery bank also wirelessly charges your phone, powers laptops etc. Jumpstarts most 4-6 cyl vehicles. car battery topped up! Heading away? Keep the 30 N 0700A Top up your batteries with solar power. This compact 5W solar panel is designed for keeping your vehicle batteries topped up when parked - ideal for when you head off on summer holidays. Croc clip or car accessory plug connection. Suits permanent outdoor install. X 3227* 75 Music sensor can trigger lights to the beat! M 8628B Keep everything charged up in the car with this handy 7.2A triple USB charger. Stylish carbon fibre look finish. Great gift idea for anyone 2! planning to travel in 202 Small enough to take anywhere you go. 5000mAh capacity. Single USB output. SAVE $30 18 $ D 0505B Automate your Christmas lights! 15 $ 37 $ A 0346 Cut standby power usage by switching appliances off at the wall. 30m RF range - line of sight to power point not requred! Requires 2xAAA batteries. 10A (2400W). Extra outlets, A 0347 $13.95. Indoor Pan & Tilt Wi-Fi Camera P 8149 Handy Wi-Fi Sockets Switch appliances on or off remotely from anywhere in the world. Set schedules, monitor and control via your using the Tuya Android/iOS app. Maximum 10A 2400W. Works with Google Home and Alexa Sale Ends December 31st 2021 Phone: 1300 797 007 Fax: 1300 789 777 Mail Orders: mailorder<at>altronics.com.au » Perth: 174 Roe St » Joondalup: 2/182 Winton Rd » Balcatta: 7/58 Erindale Rd » Cannington: 5/1326 Albany Hwy » Midland: 1/212 Gt Eastern Hwy » Myaree: 5A/116 N Lake Rd HOT PRICE! Makes a great baby or pet monitor, this camera features intelligent tracking of moving objects within the frame. 2-way audio with mic and speaker. Uses the popular Tuya app. Requires 5V 1A USB power supply. 79.95 $ S 9017A Western Australia Build It Yourself Electronics Centres USB Travel Charger & Wireless Power Bank A do-it-all USB power delivery charger (18W), Qi wireless charger and portable battery bank (6700mAh) for phones and tablets. Includes Australian, US, UK and European adaptors, plus carry case. *Phone for illustration purposes. SAVE 24% Remote Control Power Saver $ SAVE 27% 2 For This kit includes 5m of RGB strip lighting, power supply, controller unit and IR remote control allowing you to create colourful lighting effects around your home. Great for home entertaining. Works with Alexa and Google Assistant. 60 LEDs per metre. 59 A 0319* SAVE 13% Wi-Fi RGB Strip Lighting Kit 209 $ N 1130F Includes canvas carry case. Victoria 08 9428 2188 08 9428 2166 08 9428 2167 08 9428 2168 08 9428 2169 08 9428 2170 » Springvale: 891 Princes Hwy » Airport West: 5 Dromana Ave 03 9549 2188 03 9549 2121 New South Wales » Auburn: 15 Short St 02 8748 5388 Queensland » Virginia: 1870 Sandgate Rd 07 3441 2810 South Australia » Prospect: 316 Main Nth Rd 08 8164 3466 Find a local reseller at: altronics.com.au/storelocations/dealers/ Please Note: Resellers have to pay the cost of freight & insurance. Therefore the range of stocked products & prices charged by individual resellers may vary from our catalogue. © Altronics 2021. 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. *All smartphone devices pictured in this catalogue are for illustration purposes only. Not included with product. B 0092 $ .95 Triple USB Car Charger SAVE $30 Super Slim USB Battery Bank 19.95 $ SAVE 24% $ Power your camping fridge without risk of draining your battery! Cable U S B Tester Our USB Cable Tester, introduced last month, is ideal for going through piles of cables and sorting them out. It's also a great first step in diagnosing a faulty USB-connected device. It can perform continuity and short-circuit checks on practically any USB cable and will report problems such as high resistance in the power wires; a source of frustrating intermittent faults. Part 2: by Tim Blythman I n the initial article last month, we described the reasoning and principles of operation behind the USB Cable Tester. Bristling with all the standard USB sockets, it will test and diagnose any cable with either a USB-C or USB-A (2.0 or 3.2) on one end and any of USB-C or USB-B (such as 2.0, 3.2, micro or mini) on the other end. It will report whether the cable is suitable for power only, USB 2.0 or USB 3.2 operation (and indicate whether one or two SuperSpeed lanes are present). With USB 3.2 (which has replaced USB 3.0 and USB 3.1), each SuperSpeed lane consists of four wires, forming differential pairs in both (upstream and downstream) directions. The unit scans every combination of wires among the upstream facing siliconchip.com.au and downstream facing ports. It can tell you which wires are internally shorted or open circuit to help with diagnosis and repair. The USB Cable Tester also runs pulses of up to 1A through the cable's power (VBUS and GND) wires to assess their ability to carry current under realworld conditions. The resistance and voltage drop is reported. This feature will ferret out many cables that are causing intermittent problems. When devices like portable hard drives mysteriously stop working, it's possibly due to their high current needs being hampered by poor connections. With this tool, you can weed out dodgy cables and choose the best ones for high-current applications. Now you can know for sure if it's the cable Australia’s electronics magazine or the device that's causing problems. The USB Cable Tester can also run tests when only one end of a cable is plugged in, and it does this for three reasons. Firstly, it verifies cables that are OTG (USB on-the-go) compatible, which short their GND and ID pins. This state indicates to a device that it should instead behave as a host. Since OTG cables are usually adaptors, their other end is typically a socket, so you can't plug in it at both ends. The second reason is to help those who construct and repair cables. You can use it to check individual cable halves, mainly to ensure that there are no shorts between any conductors. The third is perhaps the most important. That is to check that the very fiddly USB sockets have been December 2021  85 correctly soldered to the PCB. It's a kind of self-diagnosis, if you will. We will offer a different order of construction than usual to take advantage of this self-diagnosis feature. PCB layout The internal photos and the overlay diagram (Fig.3) show that the USB sockets all lie along one edge of the PCB. CON5, CON6 and CON8 are on a narrow neck without any surrounding components. That makes fitting those sockets easier. The other sockets (CON3, CON4 and CON7) are near the relays and buck circuitry around Q3. Since these components are only needed for the power testing and not connectivity testing, we can fit those other components after confirming the USB sockets have been soldered correctly. So, no components below the rows of resistors and above the sockets should be fitted until later, except for the two other surface-mounting parts, the 220mW resistor and the inductor L1. These are low in profile and can be fitted with the other surface-mounting parts to simplify the workflow. Enclosure Prepare the case lid as the first step because the LCD is needed to perform our initial diagnostic tests, and we need to align all the parts to fit the LCD headers accurately. Refer to the cutting diagram, Fig.4. The single 4mm hole at upper right is for access to pushbutton S1; we suggest reading the Options section below to determine if you wish to fit it (and thus whether this hole is needed). It's essential that the opening for the LCD is centred horizontally to avoid the connecting header being skewed. We used a technique that requires a sharp hobby knife, pliers (preferably wide-nosed), a hacksaw or jigsaw and a drill. You can use the bezel as a template, keeping in mind that the bezel will hide most imperfections in the top panel. Mark the edges of the hole on both sides; small holes drilled in the very corners of the cutout area will help to align the two sides. Firmly score the rectangular cutout 86 Silicon Chip Fig.3: the only parts that are somewhat tricky to fit are the USB sockets. Make sure that IC1, RLY1, RLY2, the diodes and Mosfets are orientated as shown. Note that there is a single 10kW resistor amongst the rows of 1kW parts. The USB Cable Tester might still work if you mix this up, but it will drain the battery much more quickly. The six USB sockets are located along one edge of the PCB. It is important to fit USB-C socket CON4 before the relays and associated parts are mounted on the board, so you have decent access to its pins. Tactile switches with long actuators can be hard to come by, although you can certainly use such a part if you can find it. Our assembly uses four wires to stand S1 off the PCB so that you can access it from outside the case. Australia’s electronics magazine siliconchip.com.au Fig.4: fortunately, the laser-cut bezel hides any small inaccuracies in the large rectangular cutout in the case. The LCD mounting holes must be drilled accurately to ensure that the LCD aligns with the PCB underneath. The hole marked in green is used for accessing S1, and is optional. As scrolling text can be hard to read at some LCD contrast settings, the revised firmware (C/D) halves the scroll speed and provides a hidden option 4 under calibration to adjust it (1 = original speed, 2 = default, 4 = extra slow). Kits sent after 4/11/21 have this revised firmware. with the hobby knife against a straight edge. Take care with this, as a slip with a sharp knife can really hurt you! Make a hole in the centre of the rectangle that's large enough to accept the saw blade, then use the saw to cut up to the scored edges. You'll need to make a number of these cuts around the edge to divide the rectangle into manageable pieces. Then carefully flex the plastic to snap it along the score lines and break out the centre area in small sections. If the score lines are accurate, the result will have neat, precise edges. Use the hobby knife to lightly shave small pieces of plastic from the edges of the hole to enlarge the hole if necessary and to tidy up. Another method is to drill a row of holes inside the periphery of the marked area to remove most of the plastic, then file the edges smooth until the LCD fits. This is slower but requires fewer tools. With the LCD in place, you can use it (or the bezel) to mark and drill the location of the four mounting holes. If your LCD doesn't have a pin header fitted to its underside, solder it now. When the screen comes with a header, it's usually supplied siliconchip.com.au separately. Try to keep the pins at right angles to the LCD's PCB to ensure that they will fit squarely into the header sockets on the main PCB. Mount the bezel to the outside of the lid with the four 15mm-long M3 machine screws, keeping the matte surface facing out. Secure on the inside with four nuts. While simplifying assembly, these nuts also provide the spacing necessary to clear the top of the headers on the LCD panel. Slide the LCD module over the machine screws and secure it with the remaining M3 nuts. The top of the LCD panel should sit just proud of the bezel on the outside of the lid. You can see this in our photos at the end of the article. Using four self-tapping screws, secure the main PCB to the other half of the case. This will allow us to align the headers to the LCD and solder them in exactly the right place. There should be a 20mm gap between the main and LCD PCBs when the case pieces are assembled. Note that the enclosure will only fit together one way, so check that it slots together with the LCD1 pads on the PCB in line with the LCD panel's pins. If the LCD panel's pins are Australia’s electronics magazine above the USB sockets when the case is assembled, remove the PCB and rotate it by 180°. If you have 20mm spacers, you might like to use them (and the three mounting holes on the PCB) to align the LCD. Doing it that way is less fiddly. Before proceeding, check our photos of how the header sockets are fitted to the main PCB. Note that they only occupy the six end positions of each end of the header; the four central positions are not connected (as they are not used in the LCD's four-bit mode). Separate the case pieces and slot the sockets onto the LCD's pins as described above. Then place the two case pieces back together. This should align the socket pins into the pads on the main PCB. If you are having trouble, try aligning one edge of the case and pivoting the other end closed. This will bring the pins into location one at a time. With the pins located, screw the case halves together to secure everything in place. Then use your soldering iron to tack one pin to the main PCB at each end of the two headers (four pins in total) through the side opening. This is easiest at the end near the top of December 2021  87 Using the finished USB Cable Tester is as easy as plugging one end of a cable into a Downstream Facing Port, the other end into an Upstream Facing Port and then checking the LCD for its assessment. the PCB. Once you are happy they are secure and still correctly aligned, disassemble the case. Now solder the remaining pins without disturbing the alignment and then refresh any pins that might need it. At this stage, you should be able to reassemble the two halves with the pins lining up and seating into the header, pivoting the case as described earlier. If you're having trouble with the alignment, you could instead join the LCD to the main PCB with ribbon cable, strands of hookup wire or similar. Keep in mind to follow the correct pin ordering and use at least 5cm of cable for each connection to allow for flex when the case halves are separated. Remove the main PCB from the case to continue the construction. To simplify testing, we recommend detaching the LCD from the lid to allow the bare PCB to be attached to the LCD and powered up later while allowing access to the test points and jumpers on the PCB. Soldering the USB sockets Some of these are surface-mounted, so the usual collection of SMD tools is required. With CON4 and CON6 being some of the finest pitch parts we have worked on, a magnifier is a necessity, as is a good source of bright light. A mobile phone camera set to a high digital zoom level is an excellent alternative to a magnifier. 88 Silicon Chip You should also have a fine-tipped adjustable soldering iron, flux (preferably paste) and tweezers. Fortunately, most of the USB sockets (except for CON8) have locating pins, making exact positioning easy. Your flux should recommend a solvent to use for cleanup. Some desoldering braid (solder wicking braid) is a cheap and handy thing to have on hand for fixing any bridges or other situations where there is too much solder. Remember that flux can generate smoke. Use a fume extraction fan or work outside if necessary. Working outside is another way of getting decent illumination. Start with the mini-USB socket, CON5. Apply flux to the pads, rest the part in place (locking its plastic pins into the PCB holes) and apply a bit more flux to the top of the pins. Ensure that it is flat against the PCB. Also try to keep the part square and parallel to the PCB so it will align correctly with the front panel. Clean the iron's tip and apply some fresh solder to it. Then apply it to the point where the pins meet the pads. If you can't get in close, try applying the iron to the extended pads and allow them to draw solder off the iron tip. If you get a good fillet at the point where the pin meets the pad, then all is well. Do the remaining pins, then turn up the iron slightly to secure the mechanical pads. Clean the tip and Australia’s electronics magazine add fresh solder as needed. Pay attention to the mechanical pads, as these sockets will see a rough life and be subjected to repeated insertions and removals. There is also a through-hole pad accessible from the reverse of the PCB to help secure the shell of this part. Flip the PCB over and apply the iron to the pad. Gently feed in solder until the hole fills up. There should already be flux present if you have used it generously; if not, add a little more. Now use the same technique for CON8, the micro-USB socket. It has no locating pins, so you will have to take extra care with its alignment. Its front should be parallel with CON5 and its pins centred in their pads. Work one pin at a time to avoid bridges. If you get a bridge, remove it with extra flux and solder braid. Like CON5, turn up the iron to solder the larger mechanical pads. There are also extra pads underneath the PCB to help secure CON8; solder these similarly. CON4 and CON6 are the trickiest part of this build; the other two remaining USB sockets (CON3 and CON7) are through-hole only parts. The most significant trouble we had with pins on these parts bridging was when solder crept up to where they sit closer together, near their tops. If you keep your iron down near the PCB and just on the PCB pads siliconchip.com.au before you get back to soldering. Use your magnifier to examine the cleaned PCB. Any faults you can pick up now will be easier to see and repair before more components are fitted and may be more apparent now that the flux has been cleaned up. If you're unsure about your soldering, use a multimeter to check for continuity between the bottom ends of where the 26 1kW resistors will be fitted in the middle of the PCB, since these all go back to the USB sockets. If you find any short circuits, you can use the circuit diagram and overlay to identify the affected connector and pins. Through-hole parts A close-up view of the soldered pins on some of the USB sockets. This is what you want the solder joints to look like; glossy, with clear fillets between the PCB pads and socket pins, and no bridges between them. Elongated pads are provided for many of the pins which make soldering them significantly easier. only, you should avoid that problem. Apply flux paste before placing the socket, then add more before soldering the pins. Set up your magnifier to give you a good view, clean the iron tip and apply fresh solder. You'll see that two of the 12 pins have shorter PCB pads; these are not connected in circuit, so they do not have to be soldered. Solder the surface-mount pins, adding flux, cleaning the iron tip and adding solder to it as needed. Inspect your work closely, as it's only possible to easily remove the part and start afresh if the other through-hole pins haven't been soldered. If you think there might be bridges, use more flux and solder wicking braid to remove them. Take care not to allow solder onto the upper parts of the leads. Flux can make inspecting solder joins difficult. You can avoid the hassle of cleaning the entire board of flux for inspection by gently wiping away the flux with a cotton bud dipped in an appropriate flux solvent. When you're happy with the top of the PCB, flip it over and solder the through-hole pins. These are closely spaced too, but surface tension should keep the solder where it needs to be, and you can also use solder braid to remove bridges here. Turn up the iron and solder the four mechanical mounting pins. For these, siliconchip.com.au more solder is definitely better than less. Add some solder to the two central pads under the connector to help with mechanical strength. It might look like two pairs of the through-hole pins on each of CON4 and CON6 are bridged; the two outermost pairs in the row of eight. This is fine as they are all connected to their respective socket's GND pin. You can check this against the circuit diagram and overlay. We suggest leaving CON3 and CON7 until you can complete the self-tests, which will involve getting most of the USB Cable Tester functional. You can fit inductor L1 and the 220mW resistor now. Neither is polarised, so apply flux, rest the part in place and tack one lead with the iron. You may need more heat on L1 due to its size. Solder the second lead on each part, then go back and refresh the first lead if necessary. Now is a good time to clean up any flux that may be present on the PCB, given that all the surface-mounting parts have been fitted and there will be little need for more flux paste to be used. This will allow closer inspection of your soldering. Your flux should recommend a cleaning agent, but isopropanol or methylated spirits are good alternatives. Ensure that the board is allowed to dry and that any flammable solvents have a chance to evaporate Australia’s electronics magazine Continue by fitting the resistors, referring to the overlay diagram (Fig.3) as a guide. Fit the four 10kW parts first, then the 28 1kW resistors, then the rest. Check the resistances with a multimeter if you are not confident of the part markings. The 100W, 1kW and 10kW resistors only differ in one colour band. Once identified, solder them in and trim the leads close. To get the LCD operating so we can run the tests, we need to fit all the parts above and including IC1, except S1 and S2. If you don't have a pre-programmed microcontroller, you should install CON2 to permit programming in-circuit. Now fit D2, the 100nF capacitor near IC1, 10kW trimpot VR1, Q1 and CON2 if needed (we recommend a vertical header for CON2). Be sure to align Q1 and VR1 to the silkscreen pattern. Also solder the battery holder to CON1, running red to + and black to −. Check that D2 is a 1N5819 and that its cathode stripe faces as shown on the silkscreen. You don't need a header at CON1; you can solder the wires to the pads. The holes near CON1 are for strain relief, so thread the battery leads from below the PCB into the tops of the holes and then solder from below (see photos). While there is room to fit a socket for IC1, we don't recommend you use one. For a start, the large number of pins will make fitting and removing IC1 tricky. We only used one to allow us to test different microcontrollers. Gently bend IC1's pins to slot into the PCB, making sure that the pin 1 marker goes to the left as shown. Tack down two pins on opposite corners December 2021  89 Screen 1: on reset, the calibration prompt is displayed. This splash screen is shown for seven seconds. Calibration mode is entered if the USB Cable Tester receives an ESC character via the CON9 serial header during that time. and check that the part is flat and orientated correctly. Adjust if needed and then solder the remaining pins of IC1. If you don't have a pre-programmed chip, program it now, as described below. Otherwise, skip ahead to the Testing section. Programming Install cells in the battery holder to power the circuit (unless you have a programmer that can supply up to 25mA at 4.5-5V). You can use a PICkit 3, PICkit 4 or Snap programmer. We use the MPLAB X IPE for programming; it can be downloaded (along with the MPLAB X IDE) from www.microchip.com under the "Tools and Software" tab. Select the PIC16F18877, click "Apply", select your programming tool and click "Connect". Open the HEX file "0410821C.HEX" using the "Browse" button and then press "Program". If you see a "Program and Verify successful" message, all is well. Otherwise, check the wiring and soldering around the five tracks that go to CON2 from IC1. Two of the programming pins (PGD and PGC) are also used for probing the USB sockets at CON3 and CON4, so make sure that they are not shorting to anything else. If you have a PIC16F18875, use the "0410821D.HEX" file instead. Our original prototype used a PIC16F18875, which is why the PCB is marked with this part number. We decided to standardise on the PIC16F18877 as we think it will be more useful in the future and doesn't cost much more (it has more room for expansion). Though they are from the same family, some of their special function registers are in different locations, so the HEX files are not interchangeable. When finished, detach the programmer and power down the circuit (eg, by removing the cells). 90 Silicon Chip Screen 2: the Calibration screen has four options which are accessed by sending a 1, 2, 3 or 4 character. Sending Ctrl-C at any time will exit calibration mode. The measured battery voltage is displayed at top right to assist calibration. Testing Plug the LCD into its headers, apply power and adjust VR1, the LCD contrast control, until the display is legible. You should see a splash screen with a countdown timer, followed by the main USB Cable Tester screen. You can check the contrast voltage at VR1's wiper. Our unit reads around 1V with a fresh battery. If you see a "Ready for cable." message after seven seconds, construction is correct so far, and your USB socket soldering has no detectable faults. The Battery value should be between 4.2V and 4.8V. You can compare this with a multimeter voltage reading between TP1 and TP2; if the reading here is roughly correct but the displayed value is not, the circuit has a problem. If all is in order, you can progress to the remainder of the construction below. Problem? If there is no LCD backlight, there's likely a problem around transistor Q1. If you can light the backlight by grounding the LED cathode (pin 16) of the LCD, then it's definitely the PCB components and not the LCD. If you get a message on the LCD listing the UFP or DFP, these messages will point to USB socket pins that might be shorted. Refer to the circuit diagram and overlay to find those pins. Disconnect the power supply, make repairs and test again until you get the "Ready for cable." message. Remaining components Fit the three remaining capacitors. The two 1000μF and one 10μF electrolytic capacitors all have their positive (longer) leads facing to the right, according to the PCB silkscreen. Slot the two remaining USB sockets (CON3 and CON7) into place. Tack a couple of leads and ensure that the parts are flat against the PCB and squarely aligned to the PCB. This Australia’s electronics magazine will help align the sockets to the front panel. When the sockets look correct, solder the remaining pins and be generous with the mechanical tabs to ensure they have the necessary strength. There are two more diodes. Fit the single 1N4148 near CON4; it will sit between the two relays and is easier to fit before them. Check that its cathode stripe aligns with the silkscreen markings. The remaining diode is D3, a 1N5819 near L1. Then fit the two relays, RLY1 and RLY2. They should have one end marked with a stripe that will match the line on the PCB at the end nearest to IC1. As for any multi-lead part, solder a couple of pins and check that the device is correctly positioned before soldering the remaining pins. Then fit the other 2N7000 Mosfet (Q2) near RLY2 and Q3, the larger TO-220 P-channel Mosfet, near L1. Its marked face should be towards L1 with the tab closest to the cutout in the PCB. Ensure Q3's leads are pushed down against the board so that it doesn't foul the enclosure lid. Options The remaining parts are optional and only really needed for calibration (which isn't required). However, as we noted in the first article, you can also use S1 to wake up the USB Cable Tester without plugging in a cable. This could be handy if you are often testing just one end of a cable. The UART header, CON9, is only needed to enter calibration mode via a USB-serial module. S2 can be used to reset the microcontroller and quickly jump in and out of calibration mode. JP1 and JP2 are used to calibrate out the resistance of the internal wiring and traces. Our HEX file is calibrated with values suitable for the parts we are supplying, so there is little need to do this if you are building it from our kit. siliconchip.com.au Screen 3: each calibration value is entered in decimal. The value can be accepted by pressing Enter (CR, ASCII code 13) or cancelled by pressing ESC. You can clear the last keypress with delete or backspace. The other two calibrations are for the microcontroller's internal 1.024V reference voltage and current sense shunt resistance. The internal reference is specified to be accurate within ±4%, so the USB Cable Tester will be perfectly functional without calibration, but it will be slightly more accurate if this is done. The current sense resistor should be within 1% and won't need adjustment. The measured voltage is around 100mV with 1mV resolution, so the shunt resistance only needs to be adjusted if you can't use the specified shunt value. Values from 100mW to 500mW should work, although we have only tested the specified 220mW value. Lower values will give less accuracy, while higher values reduce the headroom to measure voltage drop in cables. Since the optional parts are supplied in our kit, you might as well fit them all if you already have them. Fit CON9 with the pins facing up; this will allow a pair of jumper wires or similar to be connected between the USB-serial converter and the PCB. Fit the JP1 and JP2 headers but leave the jumper shunts off for now, or plug them onto just one pin of the header. S2 fits flat against the PCB as it is only used for setup and calibration. It shouldn't be accessible during normal use. Snap it into the pads and ensure it is flat against the PCB before soldering. If you want to make S1 available for use after calibration, you need to drill the extra hole shown in Fig.4 and mount S1 above the PCB, near the top panel. To align everything, attach the main PCB to the enclosure using one screw in each corner. Use lengths of tinned copper wire to attach S1 to the PCB. Align S1 to the inside top of the front panel with some tape or Blu-Tack, then, after placing the lid on top, tack solder one or of the wires in place. This just needs to be enough to locate S1. Remove the tape and the lid. With the better access this provides, add more wires to secure the switch on all four corners. If you don't need external access for S1, it can be simply soldered flat against the PCB like S2. This completes the soldering for the USB Cable Tester. Double-check your work, then plug the LCD into its header. Calibration If you wish to perform calibration, connect a USB-serial converter to CON9 using female-female jumper wires. If you are using a CP2102 type (like us), the pin marked TXD on the converter connects to R on the PCB. GND on the converter connects to "−" on the PCB. Only one data line needs to be connected as the USB Cable Tester displays its prompts and responses on the LCD instead of the serial terminal. Screen 5: while the value is being saved to EEPROM, it is also displayed as a final check before returning to the main Calibration screen. siliconchip.com.au Screen 4: there is a final confirmation prompt before an entered value is committed to EEPROM. To answer the prompt, enter either upper or lower case "Y" or "N". Open a serial terminal program (eg, TeraTerm) and connect to the USB-serial converter at 9600 baud, 8 bits, no parity, one stop bit (8N1). It won't matter if your USB-serial converter has 3.3V or 5V signals. The 1kW resistor will limit the current flow, and IC1 will recognise logic levels in this range. Now power up the USB Cable Tester PCB. When the prompt shown in Screen 1 is visible, press the ESC key on the serial terminal. If communication is working correctly, you should see Screen 2. If not, check your wiring and reset the micro with S2 to get the prompt to press ESC again. At Screen 2, you can press 1, 2, 3 or 4 on the terminal to change the displayed value, as seen in Screen 3, after which you are prompted to confirm the change (Screen 4) with "Y" or "N". If you press "Y", you will see something like Screen 5. To calibrate the VREF value, measure the supply voltage between TP1 and TP2 and compare this with the displayed voltage shown at top right. The internal voltage reference is in inverse proportion to the displayed voltage. So if the displayed voltage is 1% too high (for example), increase the VREF value by 1% of its current value. With the internal reference specified being accurate to within 4%, you should not need to change this up or down by more than 40 points. Another way to calculate this is that Screen 6: with JP1 and JP2 fitted, only the Tester's internal resistance is reported. The value at the bottom of the screen is the contact resistance value. A similar screen is seen when a power-only cable is plugged in for testing. Australia’s electronics magazine December 2021  91 Screen 7: once calibration is complete, the main idle screen is shown unless a cable is plugged into the ports. The battery condition is reported and the sleep timer counts down 10 seconds before entering low-power sleep mode. an error of 0.01 in the displayed voltage (ie 10mV) is equivalent to about 2.1 VREF steps. So if the displayed value is 4.68V instead of 4.65V, add 6 points to the VREF value. The nominal shunt value should be accurate enough. You can measure the shunt resistance any time the relays are inactive (all the time in calibration mode) and there are no cables plugged in. Measure between TP1 and TP3. To calibrate the relay contact resistance, use option 3 to set this to 0mW. Then exit calibration mode by pressing Ctrl-C on the terminal or resetting the microcontroller. Attach jumper shunts to JP1 and JP2. This will simulate a power-only cable being connected, and you should get a display like Screen 6. Note down the resistance value shown, then remove the shunts. Reset the micro again and go back to calibration mode with ESC on the terminal. Save the noted value as the contact resistance and exit calibration. If you reattach JP1 and JP2, you should see a value very close to zero. At this stage, you can try out the USB Cable Tester on any USB cables you have lying around. See the Usage section for further information. Screen 8: a typical test result on a USB-C to USB-C cable shows what is expected for a fully USB 3.2 compatible cable with two SuperSpeed lanes, meaning that it has the USB 2.0 D+/D− pair as well as the SuperSpeed wires. Final assembly Power down the unit by removing the cells, detach the LCD from its header and reattach it to the lid as described earlier. Put the front panel PCB over the USB sockets on the main PCB and slot the pair of PCBs into place in the base of the enclosure. Secure the main PCB to the enclosure using the eight self-tapping screws. There are solder pads on the inside of the front panel PCB, so the panel can be affixed to the main PCB by soldering these pads to the USB sockets. The battery holder may have screw holes, but to avoid marring the underside of the enclosure, we recommend gluing it with neutral-cure silicone or construction adhesive. If you do use screws, fit self-adhesive rubber feet to the underside of the box to prevent the screws from scratching any surfaces. Slot the rear panel supplied with the case in place, then fit the cells. Carefully position the enclosure lid, feeling that the LCD header locks in place. The LCD backlight may illuminate if the unit has not gone to sleep, but there won't be a meaningful display since the LCD controller will not have been properly initialised. Allow the unit to go to sleep (the LCD backlight will go off), then plug in a cable (or press S1) to wake it up; this should reinitialise the LCD, and you should see one of the cable reporting screens (or the idle screen). If this is the case, all is well, and you can secure the two halves of the case with its two included screws. Usage Screens 7-11 show the USB Cable Tester in use. Screen 7 is the idle screen which shows the battery condition and time until the unit enters low-power sleep mode. It is present when the unit is awake, but no cable is detected. Once a cable is inserted, you should see the full diagnostic display, as seen in Screen 8. The first line shows a broad pass/fail assessment of the cable. The second line identifies the USB rating and the number of short circuits (+) and open wires (-) that have been detected. For an OK result, these are both zero. The third line shows more detailed information depending on the test results, listing the wires involved in any short or open circuits detected. The text may scroll if it doesn't fit on one line. The header on the LCD screen aligns with two 6-pin sockets on the main PCB. 92 Silicon Chip Australia’s electronics magazine siliconchip.com.au Screen 9: the Cable Tester will elicit a variety of information about a faulty cable, including what it thinks it ought to be and what problems it might have. Here, an open GND wire means that the cable will not function, even for charging. As shown in Screen 11, the results of the UFP and DFP tests are summarised so that single-ended tests may be carried out. This is done by unplugging one end of the cable at a time, leaving just the UFP or DFP connected. It's common that the DFP and UFP tests will detect that GND is shorted to the shield. This is the case for some USB-C cables and doesn't seem to cause any problems. The final line summarises the results of the current pulse test. Values around 200mW can be expected for cables in good condition. Up to around 500mW, they could work fine, especially for light loads; higher values indicate a cable that may cause problems. You can test cable combinations, such as when a cable is supplemented by a USB extension cable. However, as we noted, high-speed signal integrity is not tested by the USB Cable Tester. If you want to check a USB extension cable, first test a cable with a plug that will fit into it on one end (ie, A-type or C-type) and a B-type or C-type on the other; ideally, a USB 3.2 SuperSpeed type, although you can still do the test if you don't have one. Verify that cable is good and note its type and resistance. Then plug that cable into the extension cable and test the combination. Subtract the resistance reading noted earlier from the new reading to measure the extension cable's own resistance Screen 9 shows what might be seen if the cable has a fault; the first line indicates this. The second line lists the nearest 'working' cable type to what has been detected and also the number of faults present; in this case, '1-' means that this is most likely a USB 2.0 cable but with one conductor open circuit. The third line indicates that the open wire is the GND conductor, so it is unlikely to work at all. The "High resistance" message is only shown when the cable is incapable of carrying siliconchip.com.au Screen 10: with USB-C cables being reversible, it's necessary to test them with both insertion orientations. If this screen is seen, the current orientation does not connect the D+/D− pair and you should try another orientation. the lowest 100mA test current. The display in Screen 10 needs some explanation. USB-C leads only have one D+/D− pair (the wires required for a legacy USB 2.0 connection) but can be plugged in one of two ways, and some cable orientations do not detect this pair. In this case, the USB 3.2x2-2.0 indication is shown. That means that two of the SuperSpeed lanes needed for a USB 3.2 connection are detected, but the USB 2.0 wires are not. For these cables, you must try each USB-C plug both ways around (rotated 180°). If only one end is USB-C, run the test one way and flip it to try the other. If you have USB-C at both ends, flip one end, flip the other, then flip the first end back; this will test all four plug orientation combinations. You should get a USB 3.2x1 or USB3.2x2 result for only one of these tests, with the USB 3.2x1-2.0 or USB 3.2x2-2.0 indication for the remainder. That is, unless your cable has an extra D+/D− pair, which is non-standard, but it could still work on some devices. If all the combinations show USB 3.2x1-2.0 or USB 3.2x2-2.0, there is a problem with the D+/D− pair either being missing or open-circuit. The x1 designation means one SuperSpeed lane is present, while x2 means two lanes, which is only possible with a USB-C to USB-C cable. Screen 11 shows a typical UFP-only test result. If short circuits are detected in both the UFP and DFP simultaneously, but no continuity is detected between the two ends, then the UFP and DFP screens will alternate. This either means that your cable has failed very badly or (more likely) you have two different cables plugged in. For Screen 11, one end of an OTG cable has been plugged in. The fourth line shows a specific message for this case – it has detected that the GND and ID wires are connected. Only short circuits are shown on this screen, as usually, there should be no connections between pins. If four or more pins are listed, they might not all be shorted together, but they will all be shorted to at least one other pin. Up to 11 wires can be displayed, so there might be more than those shown if the screen is full. Also remember that you must always connect a cable between one of the UFPs and one of the DFPs. For example, a normal USB-A to USB-C cable can be plugged into the two DFP sockets, but this will not give a meaningful result; the USB-C end should instead be plugged into the UFP socket. Conclusion With this comprehensive and easyto-use piece of test gear, you can now sort through all your old USB cables and see whether they are worth keeping. With a 30μA sleep current, the USB Cable Tester will happily sit for years on the shelf, always ready. For a final flourish to your USB Cable Tester, you can carefully apply some white acrylic (or similar waterbased paint) to the etched text on the front of the LCD bezel. Wipe the excess away with a damp cloth and SC allow to dry. Screen 11: a typical use for the single-ended cable tests is checking if OTG cables correctly ground the ID pin. Here we see that is that case, with a specific message provided on the bottom line. Australia’s electronics magazine December 2021  93 Vintage Television Restoring Restoring aa Sony Sony 5-303E 5-303E Micro-TV Micro-TV The Sony 5-303 Micro-TV was revolutionary in 1962. It set the stage for what Japanese electronic engineers do very well; miniaturise things. It was not Sony’s first miniature TV, though. In the USA, the small Philco Safari TV beat Sony’s first small transistor TV, the TV8-301, to market in 1959. Fig.1: these specifications may not seem anything special today, but in the early 1960s, they were a big deal. 94 Silicon Chip Australia’s electronics magazine By Dr Hugo Holden The Sony Micro-TV sported a new generation of silicon power transistors that had temperature specifications and stability unheard of compared to the germanium transistors that preceded them. Sony developed these transistors especially for use in their own TV sets. The one that was proclaimed to be the mover and shaker was the 2SC140 (see Fig.1). Clearly, Sony was very proud of this transistor and they wanted to show off its spectacular features. The 2SC140 was used in the vertical output stage and the horizontal oscillator and horizontal driver. Oddly, there was a 2SD65 NPN Germanium transistor buffer stage between them, the importance of which will become clear later. Other silicon transistors used were the 2SC15 as the video output device and a 2SC41 as the horizontal output transistor. Generally, the rest of the transistors in the set are germanium PNP types, including those in the tuner, IF stages and the push-pull transformer-coupled audio amplifier. 2SC73 NPN germanium types are also used. Other interesting features of this set include a somewhat retro unregulated 12V DC power supply based on a selenium bridge rectifier (see Fig.2). The EHT rectifiers were 1DK1 small tube diodes, a commercial type, wired as a voltage multiplier to produce 8kV for the screen. As this EHT voltage is very high for the screen size (just under 14cm diagonal), the set can produce amazing high-contrast images even in bright light; screen brightness is quoted as 500 lux by Sony. The CRT (Fig.3) is a 5-inch (13cm) 70° deflection type specially designed by Sony. Its specifications are shown in Fig.4. Not mentioned there is the resolution, which is 300 columns x 400 lines, at 28 columns/cm and 45 lines/cm. siliconchip.com.au Fig.2: selenium rectifier stacks are famous for producing lots of toxic fumes when they fail. That’s why many people prefer to replace them with modern rectifiers. Still, you have to be careful because modern rectifiers can lead to much higher surge currents and have lower forward voltages. ► Fig.3: the 5-inch 140CB4 CRT was designed for this application. It provides excellent contrast. Fig.4: specifications for the cathode ray tube used in the Sony 5-303E Micro-TV. Block diagram It was customary at the time to include a block diagram in the manual (Fig.5). It shows the arrangement of the diodes and transistors. The label at the rear of the TV also says how many diodes and transistors the TV contains. Since these were expensive items, there was perceived value in the number of semiconductors inside: 25 transistors and 20 diodes (five of the transistors were silicon types). The Micro-TV was amazingly sensitive; Sony quoted a maximum sensitivity of 10µV at the input for 10V at the picture tube cathode. The set also had a gated AGC system, which was advanced for the time. The power consumption was quoted at 13W on AC operation and 9.6W from DC (12V). The set weighs in at 3.5kg (8lbs). I read on a website that this sets “runs hot”, which is nonsense. At 13W, given the size of the set, it barely warms up, and there is plenty of convection cooling. Sony’s goals for this TV were: 1. Be small in size & low weight. 2. Have the lowest power consumption of any mass-produced TV. 3. Operate perfectly as a completely portable TV set under all conditions. 4. Provide easy servicing. That last objective has now all but completely disappeared from the electronics industry. Many items now are designed for rapid and expedient assembly at a factory. Disassembly and repair is another matter, if it can even be done without special tools etc. Items are “life cycled” and the expectation that a customer would have any items repaired has siliconchip.com.au Fig.5: helpfully, Sony provided this block diagram in the TV’s user manual, showing the role of each transistor and diode. Fig.6: this diagram shows the minimum and maximum signal levels which can be expected throughout each stage of the TV during reception. Australia’s electronics magazine December 2021  95 faded away, into a new age model of replacement goods. Sony claimed that the AGC system (with its pulse or gated design and the automatic noise suppression they dubbed ANS) would maintain synchronisation in a moving car where the signal strength varies suddenly and almost continuously, even in the presence of intense ignition noise. Sony also published a very unusual and helpful signal level summary that is seldom seen in other manufacturers’ TV service manuals, shown in Fig.6. As indicated, the maximum signal gain is an astonishing 120dB. In practice, I have found that for a stable visible picture and sync, it requires about 100µV input at the set’s 75W input connector. By about 150-200µV, it is driven just out of the snow and a superclean video image results. Two PCBs Cleverly, to help servicing, Sony broke the set into two PCBs, one near the top of the chassis and one below. They have similar geometry, with a cut-out near the front for the CRT bulb and a connector at the rear. The upper board is shown in Figs.7(a) & (b). It contains the AFC (automatic frequency control for the Figs.7(a) & (b): the upper PCB has the components for automatic frequency control/horizontal hold, the horizontal and vertical scan oscillators and the horizontal and vertical scan power output stages. 96 Silicon Chip Australia’s electronics magazine siliconchip.com.au horizontal hold system), the horizontal and vertical scan oscillators and the horizontal and vertical scan power output stages. On account of this, Sony created aluminium flanges that extended from the PCB area to the front metal escutcheon of the set, to move heat away from the power output devices. Fig.7(b) is the overlay diagram from the manual, with the tracks shown as if you are looking through the component side of the PCB. When working on the underside of the board, it can be useful to scan these into a computer and flip them over, so the tracks seen on the diagram match the tracks that you see on the PCB surface. That is especially true for the upper PCB, as it is mounted with the tracks facing upwards and the components out of view. The signal board is equally as impressive for the time, and is shown in Figs.8(a) & (b). Restoration Back in the late 1970s or early 1980s when I bought this TV, it was defective. Even by then, nearly all the small electrolytic capacitors had failed, except for the Alox types (described below). The large main power supply capacitors were OK (and interestingly, they still are). I recapped the set and did a full RF alignment with a sweep generator and scope. I found some of my original notes from that time, where I kept a record of the video IF response curve and how the particular IF adjustments affected it (Fig.9). I also kept notes on the sound IF alignment. The sound response and adjustments are ideal when the set is tuned such that the high-frequency detail in the video image is optimal. I adjusted the IF bandwidth of the set at 3.75MHz (as per Sony specs). I found that the 3.8MHz bars from my pattern generator were easily resolved. The 4.8MHz bars are not visible, as expected (see Fig.10). This is the sort of performance you can expect to get with the video IF correctly set up with a sweep generator and oscilloscope. Latter-day TV restorers often try to set up the video IF by other methods, but I’m afraid there are no shortcuts here, and for excellent results there is no escaping the need for the sweep generator and scope. siliconchip.com.au Figs.8(a) & (b): the signal board carries the remaining TV circuitry not on the upper “deflection” board. Australia’s electronics magazine December 2021  97 3.8MHz Bars Fig.10: as you would expect from a set with an IF of 3.75MHz, the 3.8MHz bars in this test pattern are distinct while the 4.8MHz bars simply appear as a solid grey block. Fig.9: a redrawn version of my handwritten notes on the shape of the video IF curve and location of the adjustments on this set. I made these some time in the late 70s or early 80s. Note that while my TV has a VHF tuner, the Sony Micro-TV was also released with a UHF tuner. These were popular in North America. Fixing it up Fortunately, the set I acquired had few mechanical problems. One known weak point with these sets is the antenna clip. The plastic hardens and cracks with time, as shown in Fig.11. Mine was a victim of this, so I simply handcrafted a new one from a block of Nylon (Fig.12). This little TV sat in its box for about 40 years after I initially recapped it. I only occasionally used it. Recently, I pulled it out again. Despite just being in storage, it had developed some faults. One fault in particular was intermittent and very difficult to solve; it took a few days and a lot of patience to get to the bottom of it. 1. The vertical deflection linearity was poor at the bottom of the scanning raster. This was not correctable with the height and linearity controls. This is often a symptom of high-ESR electrolytic capacitors in the vertical output stage area, but that was not the case. 2. The horizontal hold was intermittent, with a combination of small left and right jittery movements of the horizontal position of the image, intermittently disappearing for some hours, then returning. There was also the occasional total loss of horizontal hold at times, with a sudden loss of raster width. The H-oscillator would abruptly run a much higher frequency than it should, around 20kHz. Improving vertical linearity For #1, I checked the power supply, the resistors and the electrolytic capacitors in the vertical stages; none were out of spec or defective, including the vertical yoke coil’s coupling capacitor. Fig.13 shows the vertical linearity problem. The horizontal linearity is also not ideal; this is discussed later, as it is intrinsic to the design and not easy to fix. As can be seen, the raster lines are compressed toward the bottom. In this set, there is plenty of height control and the raster will easily double in height, so there is plenty of dynamic range in the output stage. However, the vertical linearity control only has a significant effect at the top of the raster. One might think that to acquire a linear vertical scan, the Fig.11 (above): pretty much all Sony 5-303E sets will suffer from a broken plastic antenna clip by now, as the plastic becomes brittle over time. Fig.12 (right): I hand-crafted this replacement antenna clip (circled in red) from a small block of Nylon. It isn’t pretty, but it works. I could paint it grey in future for a more factory appearance. 98 Silicon Chip Australia’s electronics magazine siliconchip.com.au current in the vertical output transistor should be a linear ramp, during scan time at least. On testing with the scope, with the raster shown, the transistor’s current appeared as a near-perfect linear ramp, but this is not normal. However, to get a linear scan given the properties of the vertical yoke coils, the yoke coupling capacitor and the collector load choke need to be compensated for. So the current and transistor base drive voltage that is required for a linear raster scan needs to flare upwards toward the end of the scan. This is shown with the required waveform (red star in Fig.15) in Sony’s manual. Sony achieved the upward curve by placing positive feedback around the vertical output stage with C707, a 10µF electrolytic capacitor, and R714, a 620W resistor. This feedback is not enough to cause the amplifier to oscillate, but resulted in the upward rise of current in an exponential-like manner towards the end of scan time. The positive feedback also helped with a fast flyback. Yet in my set, with original-value resistors and capacitors and tested transistors, the output stage current was more of a linear ramp, and so the raster was compressed at the bottom. Also, the sawtooth voltage developed across 100µF capacitor C702, by the 330W charging resistor R704, was closer to 4V peak-to-peak, rather than the 2Vpp specified in the service manual. One aggravating factor here is the 20ms interval with a 50Hz vertical scan frequency versus the 16.7ms interval for the 60Hz scan frequency used in the USA. The voltages here also agreed with calculations. This means that, in the 50Hz system at least, the height control needs to be set at near minimum (larger resistance). This reduces the value of the positive feedback signal that is mixed in with the sawtooth voltage (as it has to pass via the height control) to the vertical amplifier’s input at transistor X17’s base. This aggravates the compression of scan lines toward the end of the scan, at the bottom of the raster. I corrected the poor scan linearity by increasing the value of R704 from 330W to 750W. That reduced the amplitude of the sawtooth voltage across R704 to 2.4V peak-to-peak, close to the manual’s suggestion of 2Vpp (with siliconchip.com.au Fig.13: after taking my set out of storage, I noticed that it had very poor vertical linearity, as is apparent from the ‘squashed’ blocks at the bottom. Fig.14: et voila, with a few minor component modifications, the set demonstrated far superior vertical linearity. Fig.15: the vertical deflection section of the circuit, with expected waveforms. Note how the waveform at the bottom of C702 is a linear ramp, while the base of X18, the vertical power transistor, has a modified ramp with an accelerated rise rate towards the end of the ramp. This compensates for the properties of the vertical yoke coil, to provide better vertical linearity. My set was missing that spike. this change, the most negative part of the sawtooth waveform sits at 6.6V). This meant that the height control could be adjusted for a lower resistance (more height). This improved the positive feedback. To further improve the situation, I changed C707 from 10µF to 15µF, increasing the positive feedback. Australia’s electronics magazine Another helpful change was to parallel a 3W resistor with the existing 3W resistor in the emitter of the vertical output transistor. Normally, the voltage across this resistor is 0.33V, giving an emitter current of 110mA. With the extra resistor added, the voltage drops to 0.22V across 1.5W, and the new emitter current is 146mA. December 2021  99 Fig.16: to track down the faults in the horizontal sync circuitry, I had to disconnect one leg of the 3kW resistor from its pad with solder wick. That disabled the AFC, allowing me to figure out whether the fault was in the horizontal oscillator or the AFC circuitry (it turned out to be the latter). This increase of about 36mA takes the transistor’s power dissipation from about 1.32W to 1.75W. Sony advises that the 2SC140 is capable of 1.75W without a heatsink, and in this case, it has a heatsink and only runs warm to the touch. Probably, there are some aging effects on this transistor over time. I do not want to replace it because of its historical significance. The result after these vertical linearity corrections is shown in Fig.14. I think you will agree that it’s a big improvement. Horizontal instability Once the vertical scan linearity problem was solved, I moved onto to the horizontal image instability and hold problems. Solving this was trickier than usual, as there were actually three problems. The section of the circuit shown in Fig.16 helps to explain it. Firstly, on the simple side of things, the HOR. HOLD preset was defective and at a certain point of its rotation, the resistance value suddenly jumped (not corrected by cleaning). If it was set near that position, the resistance value was erratic. So I replaced it with a modern 10kW preset pot on a small piece of plated through-hole spot board, as shown in Fig.17. Notice that the resistors are radial types, to stand up off the PCB; most are 5% tolerance parts. All but one of these resistors in my set were in excellent condition. The cause of the sudden massive change in horizontal frequency was very interesting. NPN germanium buffer transistor X22, a 2SD65, was intermittent. It would suddenly lose its ability to buffer, and the sudden loading on the horizontal oscillator forced the scan frequency up very high, to around 20kHz, well outside the capture range of the AFC. I concluded that one of two things was happening to this transistor: either the collector connection inside the transistor was intermittently going open-circuit, or the base-to-emitter terminals inside the transistor were being intermittently shorted out by something like a tin whisker. Both mechanisms result in the same failure to buffer. Of the two, I’m very suspicious that it is tin whisker disease, because I could not detect any voltage drop at all across the base-emitter junction at the time of the failure, and one would have expected about 300mV. A suitable NPN Germanium transistor replacement for the 2SD65 is an AC127. In this case though, since it is a switching circuit and not an analog circuit with specific bias requirements, Fig.17: one of the preset pots had gone bad, and since I couldn’t easily source a replacement, I rigged up a modern trimpot of the same value to fit in the same location. 100 Silicon Chip Australia’s electronics magazine siliconchip.com.au Alox Capacitors These capacitors are very interesting. They are potted in a brown resin, somewhat reminiscent of a modern-day tantalum capacitor, but they have a wax coating over the resin too. They have a logo I cannot recognise; it has some similar features to the Siemens logo, but it is not exactly the same. I copied it as best possible below. On testing the leakage properties of these Alox capacitors, they are very similar to a Tantalum capacitor. It is interesting that Sony used these in their sets, since they had the advanced technology to make silicon transistors and might have made their own capacitors if they had wanted. The fact these capacitors are all working nearly 60 years later says a lot. Presumably, they are some sort of solid aluminium electrolytic (modern and the transistors around it are silicon types, I simply replaced it with a high-quality gold-plated leg vintage BC107A (Fig.18). Usually, I would replace a germanium transistor with an equivalent germanium type, to avoid any other changes in the biasing. But in this case, it didn’t matter. The third fault was where the fun really began; it took about three days to locate because it was intermittent. After fixing the first two problems, I was initially convinced all was well. Then, much to my horror, another fault occurred. The horizontal position of the locked image had a random jitter; a few millimetres this way and that. Then the problem would disappear for some hours and return. One problem is with the horizontal AFC in lock, any changes inside the control loop from an intermittent component will be partially cancelled due to the loop behaviour. So several thoughts crossed my mind: could the incoming sync pulses be changing their shape randomly? Could the phase splitter transistor driving the AFC diodes be noisy? Could an AFC diode be noisy? Or could the old Alox capacitors be defective? Or maybe the horizontal oscillator transistor was defective and noisy, and having erratic small frequency offsets to cause the effect? I decided the better move was to siliconchip.com.au versions are available). The one marked 5µF read as 6µF on my meter. Even though these capacitors tested perfectly, I replaced the 1µF and 2µF ones with non-electrolytic Wima MKP 50V types (the pink-red colour ones seen in the photo of the deflection board) and the 5µF with a 6.8µF 50V tantalum. This will hopefully avoid any future problems; but who knows, these vintage Alox capacitors may well still be better than modern types. 57 years is a pretty good test window. break the loop (red star in Fig.16). I fed in a clean DC control voltage to the horizontal oscillator via R801 (3kW) and watched the test pattern float by horizontally. The oscillator appeared very stable, certainly with no jitter, so at least that part of the circuit was ruled out. Looking at the AFC voltage on the scope with the broken loop, the fault was present. The DC level of the AFC voltage was randomly jumping up and down about 50-100mV at times. I also tried feeding clean sync pulses from the generator directly into the phase splitter X15, but the fault remained. At that point, I disconnected the two coupling capacitors on the legs of the phase splitter output (green stars on the diagram) using solder wick and a temperature-controlled soldering iron (these old phenolic PCBs are very heat-sensitive). The fault remained, so that ruled out the phase splitter transistor, its resistors and the two disconnected capacitors. At this point, I thought the most likely explanation was that one of the IT22 germanium AFC diodes was defective and probably noisy. I replaced them one at a time with OA47 diodes. The fault and the jitter on the AFC output remained. At this point, I double-checked all of the capacitors. I had previously replaced Alox capacitors C611 and C607 with high-quality Wima Fig.18: despite being a silicon transistor, the BC107A (left) was a perfectly fine replacement for the internally faulty germanium 2SD65 (right) in my set. That’s only because of the way it was used in the circuit though; it isn’t operated in a linear manner. If it were, a germanium replacement with similar properties would have been required. Australia’s electronics magazine Fig.19: this innocent-looking 100W 5% resistor was the source of all my frustrations! It measured OK by itself, but when current passed through it, its resistance varied wildly. December 2021  101 102 Silicon Chip Australia’s electronics magazine siliconchip.com.au The complete circuit of the Sony 5-303E Micro-TV. It’s astoundingly elegant, using just 25 transistors and 25 diodes for all functions. non-electrolytic types. I eliminated all the other capacitors by desoldering one leg and by substitution. The intermittent fault still remained. At this point, I was running out of ideas, so I started checking the resistors. I was worried that if I heated them, the fault might vanish. Looking at the circuit, I could see no reason why I couldn’t eliminate each one in a test by shorting it out, avoiding the need to desolder any. The resistors to test for noise were R610, R611, R612, R614 and R615. All of these resistors had correct values on the meter. When I shorted out 100W resistor R612 (Fig.19), the voltage jitter vanished. The intermittent fault causing the small, yet apparent horizontal picture shift was due to this resistor. Inspection of the resistor showed it to look physically normal, but on testing and passing a current, its resistance value was erratic. it doesn’t have a width control inductor either. That explains why the Sony Micro TV has those horizontal linearity errors. If a technician sees these errors and wants to fix them, without realising that they are inherent to the design, they could spend months trying to improve it. It is quite different with the vertical scan linearity, which can be adjusted simply by changing the drive wave shape to the vertical scan amplifier. To correct these horizontal scan linearity errors would require more horizontal scan width, meaning an increased HT with the same line output transformer and yoke, and the addition of a width control inductor, an S-correction capacitor and magnetic saturable reactor. So it is not a practical proposition. In this case, I thought it better to accept those errors as a feature of the simpler design. Horizontal linearity Raster scanning Also noted from the screen photos, the horizontal linearity is a little stretched on the left compared to the right. In more modern video monitors and TVs, two things are done to correct horizontal linearity errors. One is to have an S-correction capacitor in series with the horizontal yoke coils; the other is to have an adjustable magnetically saturable reactor coil in series too. This set has neither an S-correction capacitor or a magnetic linearity coil; I think it was a pretty astonishing feat that Sony came up with an effective vertical oscillator and scan circuit that used only three transistors in total. Because of this, it is not surprising that the adjustments and mix of currents at the input to the two-stage vertical scan amplifier (transistor X17 and output stage X18) are critical for a linear scan. A more modern TV would contain at least two or three or more transistors. So I cannot but admire the genius, Fig.20: Sony’s follow-up was the 5-307 TV, and as you can see here, there are many similarities with the 5-303 (compare this to Fig.15). But they also made some well-advised changes, including some which addressed the very same vertical linearity problems that I encountered in my set. siliconchip.com.au Australia’s electronics magazine simplicity and economy of what Sony did with the vertical oscillator and scan amplifier. Later though, they changed the design. Sony’s next model, the TV 5-307U, sported a UHF tuner. It seems that Sony might not have been entirely happy with the design of the vertical scan oscillator and amplifier in the TV 5-303. Sony modified the positive feedback loop design in the 5-307 (Fig.20), as I had to in my 5-303, but in a different way, eliminating C707. They also used a silicon oscillator transistor, lowered the value of sawtooth capacitor C702 from 100µF to 20µF, and used a higher value charging resistor, 2.7kW vs 330W. On top of this, they modified the collector-to-base bias resistor R706 on input transistor X17. It is now split into two resistors with a 10µF capacitor to bypass the AC component of the negative feedback. This has the effect of increasing the AC signal gain of input (drive) transistor X17. There are also some other value and transistor type changes. Final points If this set is run from a 12V external battery, it is vital that a resistor of at least 1-1.5W is placed in series with the battery. This is also shown on some of Sony’s diagrams, but not all. The reason is that a lead-acid battery can have a very low internal resistance, especially a car battery. Fig.21: I added these three components to protect the CRT from damage at switch-off due to a bright spot appearing in the centre of the screen. It’s caused by the immediate shutdown of the horizontal and vertical deflection, while the electron beam continues for some time. These components shut down that beam at switch-off. December 2021  103 Just how small is this set? This advertisement from Life Magazine, March 1963, shows this amazing little TV set. While I didn’t realise it at the time, it was very clever marketing to show the Micro-TV next to two very young children (possibly around four years old). It gives you an immediate idea of the size of the set, while also showing a reallife application a parent might benefit from: the entertainment of young children. Sometimes, advertising agencies actually do a great job. In more recent times, the field of advertising has been cynically renamed “perception management”. The text at the bottom of the advert reads: “People once said Micro TV might happen in the Seventies. Sony research and engineering made it happen a year ago. This revolutionary set weighs just 8 lbs, and is about the size of a telephone, yet it outperforms standard receivers in both sensitivity and durability. And it plays anywhere... on its own rechargeable battery, 12V auto-boat battery, or AC.” “You can put the Micro TV beside your bed, on your desk, in your boat, car, den, patio or picnic basket. High fidelity sound is always assured. Epitaxial transistors – the powerful, sensitive type used in advanced electronic equipment – give it a matchlessly sharp, clear picture. See it at a Sony dealer. Be among the many enjoying the Set of the Seventies today.” 104 Silicon Chip Australia’s electronics magazine When the heater in the CRT is cold and has a very low initial resistance, the surge current can be extreme enough to bright-flash part of it and even fuse it. With the resistor, in conjunction with the high-value filter electrolytics in the set, the CRT heater gets a softer start, and the voltage applied to it rises more slowly. Also, on my set (and this problem affects many TVs of the era), at turn off, when the CRT’s scan stages initially stop the deflection, the CRT heater is still warm and the CRT’s electrode voltages can stay up for a while. The intense energy applied to the phosphor near the centre of the screen can damage it over time, so it loses its sensitivity in that area. Many TV and VDU manufacturers added “turn-off spot killers” to prevent this problem. The other thing that helps is to remember to turn the brightness to zero before powering the TV off. I added a small turn-off spot killer circuit to my set, as shown in Fig.21. It charges a capacitor from the power supply via a diode. This is so that, in case the TV gets turned off and on rapidly (or has a bad power supply connection), the capacitor charges very quickly initially. Then when the power is switched off, the TV’s 12V supply collapses fairly quickly to zero. This takes the diode side of the capacitor to about -12V; then after a while, the capacitor discharges via the 33kW and 3.3MW resistors. This creates a long-duration negative voltage pulse at the CRT grid at turn-off, helping to extinguish the beam current. These three components are simply mounted on the lower PCB connector pins where the existing 3.3MW resistor and 0.05µF capacitor reside. There is plenty of room there. Another simple method that works is to increase the charge storage on the video amplifier circuit’s power rail (in the case where the video amp drives the cathode and is directly coupled). This can be done by powering it via a series diode and adding an electrolytic filter capacitor on the supply rail. This way, at turn-off, the cathode voltage stays high for a while, also helping to extinguish the beam. In the case where it is AC-coupled, the same idea works with some added charge storage on the brightness control circuit in the cathode. SC siliconchip.com.au Subscribe to OCTOBER 2021 ISSN 1030-2662 10 The VERY BEST DIY Projects! Two- or Three-Wa Active Crossover y 9 771030 266001 $1150* NZ $1290 INC GST INC GST SMD Test Tweezers The Tele-Com Phone Intercom Gravitational Waves how they are detected Australia’s top electronics magazine Cover1021.indd 1 Silicon Chip is one of the best DIY electronics magazines in the world. Each month is filled with a variety of projects that you can build yourself, along with features on a wide range of topics from in-depth electronics articles to general tech overviews. Published in Silicon Chip 07-Sep-21 12:34:21 PM If you have an active subscription you receive 10% OFF orders from our Online Shop (siliconchip.com.au/Shop/)* Rest of World New Zealand Australia * does not include the cost of postage Length Print Combined Online 6 months $65 $75 $50 1 year $120 $140 $95 2 years $230 $265 $185 6 months $80 $90 1 year $145 $165 2 years $275 $310 6 months $100 $110 1 year $195 $215 2 years $380 $415 All prices are in Australian dollars (AUD). Combined subscriptions include both the printed magazine and online access. Try our Online Subscription – now with PDF downloads! NASA’s 2020 Mission to Mars; July 2021 High-Current Four Battery Balancer; March 2021 SMD Test Tweezers; October 2021 An online issue is perfect for those who don’t want too much clutter around the house and is the same price worldwide. Issues can be viewed online, or downloaded as a PDF. To start your subscription go to siliconchip.com.au/Shop/Subscribe SILICON CHIP .com.au/shop ONLINESHOP HOW TO ORDER INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) MAIL (24/7) PHONE – (9-5:00 AET, Mon-Fri) siliconchip.com.au/Shop silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au PO Box 139, COLLAROY, NSW 2097 (02) 9939 3295, +612 for international You can also pay by cheque/money order (Orders by mail only) or bank transfer. Make cheques payable to Silicon Chip. 12/21 YES! You can also order or renew your Silicon Chip subscription via any of these methods as well! The best benefit, apart from the magazine? Subscribers get a 10% discount on all orders for parts. PRE-PROGRAMMED MICROS For a complete list, go to siliconchip.com.au/Shop/9 $10 MICROS 24LC32A-I/SN ATmega328P ATmega328P-AUR ATtiny85V-10PU ATtiny816 PIC10F202-E/OT PIC12F1572-I/SN PIC12F617-I/P PIC12F617-I/SN PIC12F675-I/P PIC12F675-I/SN PIC16F1455-I/P PIC16F1455-I/SL PIC16F1459-I/P PIC16F1705-I/P PIC16F88-E/P PIC16F88-I/P $15 MICROS Digital FX Unit (Apr21) RF Signal Generator (Jun19), Si473x FM/AM/SW Digital Radio (Jul21) RGB Stackable LED Christmas Star (Nov20) Shirt Pocket Audio Oscillator (Sep20) ATtiny816 Development/Breakout Board (Jan19) Ultrabrite LED Driver (with free TC6502P095VCT IC, Sep19) LED Christmas Ornaments (Nov20; specify variant) Nano TV Pong (Aug21), SMD Test Tweezers (Oct21) Car Radio Dimmer (Aug19), MiniHeart Heartbeat Simulator (Jan21) Refined Full-Wave Universal Motor Speed Controller (Apr21) Model Railway Level Crossing (two required – $15/pair) (Jul21) Model Railway Carriage Lights (Nov21) Motor Speed Controller (Mar18), Heater Controller (Apr18) Useless Box IC3 (Dec18) Tiny LED Xmas Tree (Nov19) Digital Interface Module (Nov18), GPS Finesaver (Jun19) Digital Lighting Controller LED Slave (Dec20) Ol’ Timer II (Jul20), Battery Multi Logger (Feb21) 5-Way LCD Panel Meter (Nov19), IR Remote Control Assistant (Jul20) Ultrasonic Cleaner (Sep20), Electronic Wind Chime (Feb21) 20A DC Motor Speed Controller (Jul21) Flexible Digital Lighting Controller Slave (Oct20) Digital Lighting Controller Translator (Dec21) Automotive Sensor Modifier (Dec16) UHF Repeater (May19), Six Input Audio Selector (Sep19) Universal Battery Charge Controller (Dec19) ATSAML10E16A-AUT High-Current Battery Balancer (Mar21) PIC16F1459-I/SO Four-Channel DC Fan & Pump Controller (Dec18) PIC16F18877-I/P USB Cable Tester (Nov21) PIC32MM0256GPM028-I/SS Super Digital Sound Effects (Aug18) PIC32MX170F256D-501P/T 44-pin Micromite Mk2 (Aug14), 4DoF Simulation Seat (Sep19) PIC32MX170F256B-50I/SP Micromite LCD BackPack V1-V3 (Feb16 / May17 / Aug19) GPS-Synched Frequency Reference (Nov18), Air Quality Monitor (Feb20) RCL Box (Jun20), Digital Lighting Controller Micromite Master (Nov20) Advanced GPS Computer (Jun21) Touchscreen Digital Preamp [2.8in/3.5in version] (Sep21) PIC32MX170F256B-I/SO Battery Multi Logger (Feb21), Battery Manager BackPack (Aug21) PIC32MX270F256B-50I/SP ASCII Video Terminal (Jul14), USB M&K Adaptor (Feb19) PIC32MX795F512H-80I/PT Maximite (Mar11), miniMaximite (Nov11), Colour Maximite (Sep12), Touchscreen Audio Recorder (Jun14) $20 MICROS dsPIC33FJ64MC802-E/SP dsPIC33FJ128GP306-I/PT dsPIC33FJ128GP802-I/SP PIC32MX470F512H-I/PT PIC32MX470F512H-120/PT PIC32MX470F512L-120/PT 1.5kW Induction Motor Speed Controller (Aug13) CLASSiC DAC (Feb13) Ultra-LD Preamp (Nov11), LED Musicolour (Oct12) Stereo Echo/Reverb (Feb 14), Digital Effects Unit (Oct14) Micromite Explore 64 (Aug 16), Micromite Plus (Nov16) Micromite Explore 100 (Sep16) PIC32MX695F512L-80I/PF PIC32MZ2048EFH064-I/PT Colour MaxiMite (Sep12) DSP Crossover/Equaliser (May19), Low-Distortion DDS (Feb20) DIY Reflow Oven Controller (Apr20) $30 MICROS KITS, SPECIALISED COMPONENTS ETC SMD TRAINER KIT (CAT SC5260) (DEC 21) Complete kit includes the PCB and all on-board components, except for a TQFP-64 footprint device HUMMINGBIRD AMPLIFIER (CAT SC6021) $20.00 (DEC 21) Hard-to-get parts includes: two 0.22W 5W resistors; plus one each of an MJE15034G, MJE15035G, KSC3503DS & 220pF 250V C0G ceramic capacitor USB CABLE TESTER KIT (CAT SC5966) $110.00 (NOV 21) Includes PCB, IC1 (programmed), IC2, D1, L1, SMD capacitors and resistors. Does not include reed switch, magnet, LEDs or through-hole parts SMD TEST TWEEZERS KIT (CAT SC5934) $35.00 (AUG 21) $17.50 PCB and all onboard parts only (does not include controllers) MODEL RAILWAY LEVEL CROSSING (JUL 21) $15.00 $5.00 - Pair of programmed PIC12F617-I/Ps - ISD1820P-based audio recording and playback module AM/FM/SW RADIO (JAN 21) $2.50 $3.00 $7.50 - PCB-mount right-angle SMA socket (SC4918) - Pulse-type rotary encoder with integral pushbutton (SC5601) - 16x2 LCD module (does not use I2C module) (SC4198) LED CHRISTMAS ORNAMENTS (CAT SC5579) (NOV 20) Complete kit including micro but no coin cell (specify PCB shape & colour) RGB STACKABLE LED CHRISTMAS STAR (CAT SC5525) $14.00 (NOV 20) $38.50 Complete kit including PCB, micro, diffused RGB LEDs and other parts MICROMITE LCD BACKPACK V3 KIT (CAT SC5082) $25.00 (OCT 21) PCBs, micro, other onboard parts and heatshrink (no cell or brass tips) NANO TV PONG SHORT FORM KIT (CAT SC5885) $15.00 (NOV 21) Short form kit with everything except case and AA cells MODEL RAILWAY CARRIAGE LIGHTS KIT (CAT SC6027) siliconchip.com.au/Shop/ (AUG 19) Includes PCB, programmed micros, 3.5in touchscreen LCD, UB3 lid, mounting hardware, Mosfets for PWM backlight control and all other mandatory on-board parts $75.00 Separate/Optional Components: - 3.5-inch TFT LCD touchscreen (Cat SC5062) $35.00 - DHT22 temp/humidity sensor (Cat SC4150) - BMP180 (Cat SC4343) OR BMP280 (Cat SC4595) temp/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) $7.50 $5.00 $10.00 $4.00 $5.00 $1.50 $2.00 VARIOUS MODULES & PARTS - 64x32 pixel white 0.49in OLED (SMD Test Tweezers, Oct21) $10.00 - pair of AD8403ARZ10 (Touchscreen Digital Preamp, Sep21) $35.00 - Si4732 radio IC (Si473x FM/AM/SW Radio, Jul21) $15.00 - EA2-5NU relay (PIC Programming Helper, Jun21) $3.00 - VK2828U7G5LF GPS module (Advanced GPS Computer, Jun21) $25.00 - MCP4251-502E/P (Advanced GPS Computer, Jun21) $3.00 - pair of Signetics NE555Ns (Arcade Pong, Jun21) $12.50 - 2.8-inch touchscreen LCD module (Lab Supply, May21) $25.00 - Spin FV-1 digital effects IC (Digital FX Unit, Apr21) $40.00 - 15mW 3W SMD resistor (Battery Multi Logger / Arduino PSU, Feb21) $2.50 - DS3231(M) real-time clock SMD IC (Battery Multi Logger, Feb21) $3.00 - Pair of CSD18534 transistors (Electronic Wind Chimes, Feb21) $6.00 - IPP80P03P4L04 (Dual Battery Lifesaver / Vintage Radio Supply, Dec20) $5.00 - 16x2 LCD module (Digital RF Power Meter, Aug20) $7.50 - WS2812 8x8 RGB LED matrix module (Ol’ Timer II, Jul20) $15.00 - MAX038 function generator IC (H-Field Transanalyser, May20) $25.00 - MC1496P double-balanced mixer IC (H-Field Transanalyser, May20) $2.50 - AD8495 thermocouple interface (DIY Reflow Oven Controller, Apr20) $12.50 - Si8751AB 2.5kV isolated Mosfet driver IC (Charge Controller, Dec19) $5.00 - I/O expander modules (Nov19): PCA9685 – $6.00 ¦ PCF8574 – $3.00 ¦ MCP23017 – $3.00 - SMD 1206 LEDs, packets of 10 unless stated otherwise (Xmas Ornaments, Nov20): yellow – $0.70 ¦ amber – $0.70 ¦ blue – $0.70 ¦ cyan – $1.00 ¦ pink (1 only) – $0.20 - ISD1820-based voice recorder / playback module (Junk Mail, Aug19) $4.00 - 23LCV1024-I/P SRAM & MCP73831T (UHF Repeater, May19) $11.50 - MCP1700 3.3V LDO regulator (suitable for USB M&K Adapator, Feb19) $1.50 - 1nF 1% MKP (5mm) or ceramic capacitor (LC Meter, Jun18) $2.50 - ESP-01 WiFi Module (El Cheapo Modules, Apr18) $5.00 - DS3231 real-time clock module with mounting hardware $7.50 *Prices valid for month of magazine issue only. All prices in Australian dollars and include GST where applicable. # P&P prices are within Australia. Overseas? Place an order on our website for a quote. PRINTED CIRCUIT BOARDS & CASE PIECES PRINTED CIRCUIT BOARD TO SUIT PROJECT LED CHRISTMAS TREE HIGH-SENSITIVITY MAGNETOMETER USELESS BOX FOUR-CHANNEL DC FAN & PUMP CONTROLLER ATtiny816 DEVELOPMENT/BREAKOUT PCB ISOLATED SERIAL LINK DAB+/FM/AM RADIO ↳ CASE PIECES (CLEAR) REMOTE CONTROL DIMMER MAIN PCB ↳ MOUNTING PLATE ↳ EXTENSION PCB MOTION SENSING SWITCH (SMD) PCB USB MOUSE AND KEYBOARD ADAPTOR PCB LOW-NOISE STEREO PREAMP MAIN PCB ↳ INPUT SELECTOR PCB ↳ PUSHBUTTON PCB DIODE CURVE PLOTTER ↳ UB3 LID (MATTE BLACK) FLIP-DOT (SET OF ALL FOUR PCBs) ↳ COIL PCB ↳ PIXEL PCB (16 PIXELS) ↳ FRAME PCB (8 FRAMES) ↳ DRIVER PCB iCESTICK VGA ADAPTOR UHF DATA REPEATER AMPLIFIER BRIDGE ADAPTOR 3.5-INCH LCD ADAPTOR FOR ARDUINO DSP CROSSOVER (ALL PCBs – TWO DACs) ↳ ADC PCB ↳ DAC PCB ↳ CPU PCB ↳ PSU PCB ↳ CONTROL PCB ↳ LCD ADAPTOR STEERING WHEEL CONTROL IR ADAPTOR GPS SPEEDO/CLOCK/VOLUME CONTROL ↳ CASE PIECES (MATTE BLACK) RF SIGNAL GENERATOR RASPBERRY PI SPEECH SYNTHESIS/AUDIO BATTERY ISOLATOR CONTROL PCB ↳ MOSFET PCB (2oz) MICROMITE LCD BACKPACK V3 CAR RADIO DIMMER ADAPTOR PSEUDO-RANDOM NUMBER GENERATOR 4DoF SIMULATION SEAT CONTROLLER PCB ↳ HIGH-CURRENT H-BRIDGE MOTOR DRIVER MICROMITE EXPLORE-28 (4-LAYERS) SIX INPUT AUDIO SELECTOR MAIN PCB ↳ PUSHBUTTON PCB ULTRABRITE LED DRIVER HIGH RESOLUTION AUDIO MILLIVOLTMETER PRECISION AUDIO SIGNAL AMPLIFIER SUPER-9 FM RADIO PCB SET ↳ CASE PIECES & DIAL TINY LED XMAS TREE (GREEN/RED/WHITE) HIGH POWER LINEAR BENCH SUPPLY ↳ HEATSINK SPACER (BLACK) DIGITAL PANEL METER / USB DISPLAY ↳ ACRYLIC BEZEL (BLACK) UNIVERSAL BATTERY CHARGE CONTROLLER BOOKSHELF SPEAKER PASSIVE CROSSOVER ↳ SUBWOOFER ACTIVE CROSSOVER ARDUINO DCC BASE STATION NUTUBE VALVE PREAMPLIFIER TUNEABLE HF PREAMPLIFIER 4G REMOTE MONITORING STATION LOW-DISTORTION DDS (SET OF 5 BOARDS) NUTUBE GUITAR DISTORTION / OVERDRIVE PEDAL THERMAL REGULATOR INTERFACE SHIELD ↳ PELTIER DRIVER SHIELD DIY REFLOW OVEN CONTROLLER (SET OF 3 PCBS) 7-BAND MONO EQUALISER ↳ STEREO EQUALISER DATE NOV18 DEC18 DEC18 DEC18 JAN19 JAN19 JAN19 JAN19 FEB19 FEB19 FEB19 FEB19 FEB19 MAR19 MAR19 MAR19 MAR19 MAR19 APR19 APR19 APR19 APR19 APR19 APR19 MAY19 MAY19 MAY19 MAY19 MAY19 MAY19 MAY19 MAY19 MAY19 MAY19 JUN19 JUN19 JUN19 JUN19 JUL19 JUL19 JUL19 AUG19 AUG19 AUG19 SEP19 SEP19 SEP19 SEP19 SEP19 SEP19 OCT19 OCT19 NOV19 NOV19 NOV19 NOV19 NOV19 NOV19 NOV19 DEC19 JAN20 JAN20 JAN20 JAN20 JAN20 FEB20 FEB20 MAR20 MAR20 MAR20 APR20 APR20 APR20 For a complete list, go to siliconchip.com.au/Shop/8 PCB CODE Price PRINTED CIRCUIT BOARD TO SUIT PROJECT 16107181 $5.00 REFERENCE SIGNAL DISTRIBUTOR 04101011 $12.50 H-FIELD TRANSANALYSER 08111181 $7.50 CAR ALTIMETER 05108181 $5.00 RCL BOX RESISTOR BOARD 24110181 $5.00 ↳ CAPACITOR / INDUCTOR BOARD 24107181 $5.00 ROADIES’ TEST GENERATOR SMD VERSION 06112181 $15.00 ↳ THROUGH-HOLE VERSION SC4849 $.00 COLOUR MAXIMITE 2 PCB (BLUE) 10111191 $10.00 ↳ FRONT & REAR PANELS (BLACK) 10111192 $10.00 OL’ TIMER II PCB (RED, BLUE OR BLACK) 10111193 $10.00 ↳ ACRYLIC CASE PIECES / SPACER (BLACK) 05102191 $2.50 IR REMOTE CONTROL ASSISTANT PCB (JAYCAR) 24311181 $5.00 ↳ ALTRONICS VERSION 01111119 $25.00 USB SUPERCODEC 01111112 $15.00 ↳ BALANCED ATTENUATOR 01111113 $5.00 SWITCHMODE 78XX REPLACEMENT 04112181 $7.50 WIDEBAND DIGITAL RF POWER METER SC4927 $5.00 ULTRASONIC CLEANER MAIN PCB SC4950 $17.50 ↳ FRONT PANEL 19111181 $5.00 NIGHT KEEPER LIGHTHOUSE 19111182 $5.00 SHIRT POCKET AUDIO OSCILLATOR 19111183 $5.00 ↳ 8-PIN ATtiny PROGRAMMING ADAPTOR 19111184 $5.00 D1 MINI LCD WIFI BACKPACK 02103191 $2.50 FLEXIBLE DIGITAL LIGHTING CONTROLLER SLAVE 15004191 $10.00 ↳ FRONT PANEL (BLACK) 01105191 $5.00 LED XMAS ORNAMENTS 24111181 $5.00 30 LED STACKABLE STAR SC5023 $40.00 ↳ RGB VERSION (BLACK) 01106191 $7.50 DIGITAL LIGHTING MICROMITE MASTER 01106192 $7.50 ↳ CP2102 ADAPTOR 01106193 $5.00 BATTERY VINTAGE RADIO POWER SUPPLY 01106194 $7.50 DUAL BATTERY LIFESAVER 01106195 $5.00 DIGITAL LIGHTING CONTROLLER LED SLAVE 01106196 $2.50 BK1198 AM/FM/SW RADIO 05105191 $5.00 MINIHEART HEARTBEAT SIMULATOR 01104191 $7.50 I’M BUSY GO AWAY (DOOR WARNING) SC4987 $10.00 BATTERY MULTI LOGGER 04106191 $15.00 ELECTRONIC WIND CHIMES 01106191 $5.00 ARDUINO 0-14V POWER SUPPLY SHIELD 05106191 $7.50 HIGH-CURRENT BATTERY BALANCER (4-LAYERS) 05106192 $10.00 MINI ISOLATED SERIAL LINK 07106191 $7.50 REFINED FULL-WAVE MOTOR SPEED CONTROLLER 05107191 $5.00 DIGITAL FX UNIT PCB (POTENTIOMETER-BASED) 16106191 $5.00 ↳ SWITCH-BASED 11109191 $7.50 ARDUINO MIDI SHIELD 11109192 $2.50 ↳ 8X8 TACTILE PUSHBUTTON SWITCH MATRIX 07108191 $5.00 HYBRID LAB POWER SUPPLY CONTROL PCB 01110191 $7.50 ↳ REGULATOR PCB 01110192 $5.00 VARIAC MAINS VOLTAGE REGULATION 16109191 $2.50 ADVANCED GPS COMPUTER 04108191 $10.00 PIC PROGRAMMING HELPER 8-PIN PCB 04107191 $5.00 ↳ 8/14/20-PIN PCB 06109181-5 $25.00 ARCADE MINI PONG SC5166 $25.00 Si473x FM/AM/SW DIGITAL RADIO 16111191 $2.50 20A DC MOTOR SPEED CONTROLLER 18111181 $10.00 MODEL RAILWAY LEVEL CROSSING SC5168 $5.00 COLOUR MAXIMITE 2 GEN2 (4 LAYERS) 18111182 $2.50 BATTERY MANAGER SWITCH MODULE SC5167 $2.50 ↳ I/O EXPANDER 14107191 $10.00 NANO TV PONG 01101201 $10.00 LINEAR MIDI KEYBOARD (8 KEYS) 01101202 $7.50 TOUCHSCREEN DIGITAL PREAMP 09207181 $5.00 ↳ RIBBON CABLE / IR ADAPTOR 01112191 $10.00 2-/3-WAY ACTIVE CROSSOVER 06110191 $2.50 TELE-COM INTERCOM 27111191 $5.00 SMD TEST TWEEZERS (3 PCB SET) 01106192-6 $20.00 USB CABLE TESTER MAIN PCB 01102201 $7.50 ↳ FRONT PANEL (GREEN) 21109181 $5.00 MODEL RAILWAY CARRIAGE LIGHTS 21109182 $5.00 NEW PCBs 01106193/5/6 $12.50 HUMMINGBIRD AMPLIFIER 01104201 $7.50 DIGITAL LIGHTING CONTROLLER TRANSLATOR 01104202 SMD TRAINER Australia’s$7.50 electronics magazine DATE APR20 MAY20 MAY20 JUN20 JUN20 JUN20 JUN20 JUL20 JUL20 JUL20 JUL20 JUL20 JUL20 AUG20 NOV20 AUG20 AUG20 SEP20 SEP20 SEP20 SEP20 SEP20 OCT20 OCT20 OCT20 NOV20 NOV20 NOV20 NOV20 NOV20 DEC20 DEC20 DEC20 JAN21 JAN21 JAN21 FEB21 FEB21 FEB21 MAR21 MAR21 APR21 APR21 APR21 APR21 APR21 MAY21 MAY21 MAY21 JUN21 JUN21 JUN21 JUN21 JUL21 JUL21 JUL21 AUG21 AUG21 AUG21 AUG21 AUG21 SEP21 SEP21 OCT21 OCT21 OCT21 NOV21 NOV21 NOV21 PCB CODE CSE200103 06102201 05105201 04104201 04104202 01005201 01005202 07107201 SC5500 19104201 SC5448 15005201 15005202 01106201 01106202 18105201 04106201 04105201 04105202 08110201 01110201 01110202 24106121 16110202 16110203 16111191-9 16109201 16109202 16110201 16110204 11111201 11111202 16110205 CSE200902A 01109201 16112201 11106201 23011201 18106201 14102211 24102211 10102211 01102211 01102212 23101211 23101212 18104211 18104212 10103211 05102211 24106211 24106212 08105211 CSE210301C 11006211 09108211 07108211 11104211 11104212 08105212 23101213 01103191 01103192 01109211 12110121 04106211/2 04108211 04108212 09109211 Price $7.50 $10.00 $5.00 $7.50 $7.50 $2.50 $5.00 $10.00 $10.00 $5.00 $7.50 $5.00 $5.00 $12.50 $7.50 $2.50 $5.00 $7.50 $5.00 $5.00 $2.50 $1.50 $5.00 $20.00 $20.00 $3.00 $12.50 $12.50 $5.00 $2.50 $7.50 $2.50 $5.00 $10.00 $5.00 $2.50 $5.00 $10.00 $5.00 $12.50 $2.50 $7.50 $7.50 $7.50 $5.00 $10.00 $10.00 $7.50 $7.50 $7.50 $5.00 $7.50 $35.00 $7.50 $7.50 $5.00 $15.00 $5.00 $2.50 $2.50 $5.00 $12.50 $2.50 $15.00 $30.00 $10.00 $7.50 $5.00 $2.50 DEC21 DEC21 DEC21 01111211 16110206 29106211 $5.00 $5.00 $5.00 We also sell an A2 Reactance Wallchart, RTV&H DVD, Vintage Radio DVD plus various books 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 Motor speed controller recommendation I am hoping you can point me in the right direction. I am looking for a variable speed controller, which is harder to find than hen’s teeth in New Zealand. I came across an article on your website about building one (230V/10A Speed Controller For Universal Motors, February & March 2014), then discovered that you sell some of the parts for it. If this is the correct product? Does it come with a list of instructions on how to build it and what else would be required to make it complete? I am looking to control the speed of a 230-240V 7.2A 1650W brush router (S. W., Christchurch, NZ). • While you could build that and it should work for your application, we recommend you instead build our April 2021 controller design (Refined Full-Wave Motor Speed Controller; siliconchip.com.au/Article/14814). It is cheaper and smaller than the 10A 230VAC Universal Motor Speed Controller you mentioned. The instructions for building it are all in the April 2021 issue, which you can purchase at the following links: siliconchip.com.au/Shop/2/5795 (printed) or siliconchip.com.au/ Shop/12/5797 (online/PDF). We also sell the PCB and programmed PIC for that project at siliconchip.com.au/ Shop/?article=14814 With those, you would just need to source the remaining components from a convenient electronic store, as per the parts list in the magazine. Building Reflow Oven firmware in MPLAB Can you help me import the C source files for the Reflow Oven project (April-May 2020; siliconchip.com. au/Series/343) into MPLAB IDE? I have Harmony v2.06 installed, but MPLAB doesn’t seem to import the project correctly (via the open project option). It brings in the original programmer’s file 108 Silicon Chip locations, and the project fails to build. Is there an easier way than having to alter the source file locations manually in the configuration files? (T. B., Footscray, Vic) • We have run into this problem before. You might need to create a new project and add each source file in over the template. Be aware that there are several versions of Harmony. This project uses the old “vanilla” one. We tried getting it to compile against a newer version without much luck. There are some instructions on migrating projects available via web searches, which you should hunt down. Adding tone controls to Nutube preamp I am building the Nutube Preamp project (March 2020; siliconchip.com. au/Article/12576) to combine with the 20W Class A amplifier (May-August 2007; siliconchip.com.au/Series/58) as a small guitar amp. I figure the “cleanness” of the Class A power amplifier would allow the qualities of the Nutube to be appreciated without colouration from power amplifier distortion. I wish to use the left and right channels as two mono inputs switched by one pole of a foot-switch controlled DPDT relay, the other pole switching the selected output to the main power amplifier, with LED channel indication. This doesn’t seem to pose too much of a problem for me. But I also wish to incorporate a three-stage Baxandall tone circuit in each channel. I have found several of these circuits in Silicon Chip projects, and I think the one in the 2-Channel Guitar Preamp from November 2000 to January 2001 seems like a good choice (siliconchip.com.au/Series/134). Other possibilities are Baxandall circuits from the 4-Channel Mixers from June 2007 & 2012 (Mix-It!; siliconchip. com.au/Article/644) or one gleaned from the Digital Preamp from September 2021, without the digital control. Australia’s electronics magazine Please advise how I could insert one of these into the Nutube circuit, either by using it in the feedback loop of one of the existing op amps or adding another op amp or two for the feedback loop and as a buffer. I have a couple of spare OPA1662AIDs, or I could use an LM833 or TL072 if need be. Also, effects send and receive would be a fine addition! Finally, on the Nutube PCB screen printing, parts list, component layout diagram and circuit diagram are specified three 100μF/25V electrolytic capacitors, one of which for the Supply/2 filter is shown as much smaller than the other two.Is this correct? And please explain what the dot means following the μF on some of the electrolytic capacitors in Fig.10 on page 28. (I. H., Essendon, Vic) • The Baxandall tone control circuitry could be placed as a separate circuit between the preamplifier output and the power amplifier input. We recommended that you use OPA1662 op amps for the tone control circuitry rather than LM833s. While TL072s have a low input current, they do not have the low distortion figures of the previously mentioned op amps. Your enquiry concerning the 100μF capacitors and the size differences is related to the asterisks following the capacitor values. Those capacitors with the * (asterisk) are to be 25V rated and so are larger than their 16V counterparts. Questions about the Super-9 FM Radio I have almost completed building the Super-9 (November & December 2019; siliconchip.com.au/Series/340) but have a few questions. The 33kW resistor shown above IC3 is labelled 10kW on the PCB I received. Which is the correct value? When winding T1 and L6, the parts listing states that I should use 0.25mm diameter enamelled copper wire, but in the winding instructions on p63, it says 0.125mm. Which is correct, and siliconchip.com.au should it be 11.5 turns on two layers, or do all 23 turns for T1 need to be all one layer? (R. S., Epping, Vic) • Use the 33kW resistor as shown in the articles and ignore the screen printing on the PCB. As for the T1 windings, we think it’s better to use 0.25mm diameter wire as this makes the winding easier, and it is less likely to break when winding. You can make the 23 turns in two layers (it would fit in just one layer if using the finer wire). Questions on Water Tank Meter project I have three questions about the February 2018 Water Tank Level Meter/ Weather Station project (siliconchip. com.au/Article/10963). If I cut holes in the box for relative humidity (RH) measurements, will that expose the boards and pins to corrosion from high moisture air? As I am primarily after the water tank measurement feature, can I leave out those holes without ill effect? Can I use the same kit for a second tank without the weather station components, or do I need the whole circuit to be complete? If I get this going, I would like to somehow control the pump for that tank, which is 300m away from the tank. (A. R., Darkan, WA) • If you do not have holes in the case, the RH reading will remain constant as it will measure the RH inside the sealed box and not external air. Suppose you want the RH sensing feature to work but avoid the possibility of corrosion due to moisture in the air. In that case, you’d either have to conformally coat the board (but not the sensor!) or place the sensor in a separate, ventilated compartment somehow. The RH/temperature sensor and barometer can be left out, and the water tank level sensing will still work. The circuit does not provide for controlling a water pump based on water level, but it could be modified to do so. That would require extra lines in the software, adding logic to decide when to switch the pump on and off and drive a digital output pin appropriately. As your pump from the tank, you could have another ESP8266/ESP32 query the water level over WiFi, but that would require considerable design work. siliconchip.com.au Monitoring solar power generation I have some questions regarding using solar power at home rather than selling it for the feed-in tariff. As the buy-back rates (feed-in tariff) for electricity generated with solar panels becomes lower (we have had two price reductions in the past year), it is becoming more prudent to use as much generated power at home as possible. Heating water is a good one, as I have a 1000L spa and a storage hot water system. Do you have a way to sense when generated power is going back to the grid and how much? Could this power be diverted to heat the spa or hot water system? Time clocks don’t do the job. In winter, there are times we must purchase power as the panels do not generate enough for the house usage and the spa on dull days. Should there be insufficient power available, is it possible to switch off some loads that are not needed, like pool pumps or washing machines? I have 6kW of north-facing panels on the roof. (M. S., Umina Beach, NSW) • You need an energy meter that can show power flow to and from the solar system and the power grid. We have published power meters in the past but they are not suitable for your application. However, commercial units are available. For example, see www. energymatters.com.au/flex/solarenergy-monitor/ Choosing the right ferrite bead for an amp First off, thanks for all of your team’s hard work in keeping electronics accessible to the non-engineer. I plan to build some SC200 amplifier modules (January-March 2017; siliconchip. com.au/Series/308) and am sourcing the parts. Do you have a value for the small ferrite bead, FB1? Looking at different suppliers, I see that most are from Fair-Rite Products Corp. Their Beads-on-Leads are listed by impedances at various frequencies. They are arranged as Higher Frequencies, Broadband Frequencies and Lower Frequencies. I’m assuming it is in the Broadband category, but other than that, I’m stumped. (J. R., Norco, CA, USA) • You could make an argument for looking at beads that suppress either Australia’s electronics magazine Broadband Frequencies (25-300MHz) as that covers the FM broadcast band, or Lower Frequencies as that covers AM and the sort of frequencies that virtually all switchmode converters operate at. We think the latter (Lower Frequencies) would be the most useful as switch-mode EMI breakthrough will be more of a problem than FM pickup in an amplifier in most cases. As this is a signal path, choose one with a higher impedance value. The other thing you need to check for is that it will fit in the available space. This design uses a loose bead that’s slipped over a resistor lead, so you will need a bead without a lead about 5mm long. It would be possible to solder a resistor and ferrite bead in series, in an inverted-V shape off the board, if you particularly wanted to use a beadon-lead style product (in which case their product number 2773005111 would be good). While both are likely tight fits, you could try their product number 2673028602 at 5.6mm long or, for better performance, 2673000301 at 6mm long. You should be able to squeeze those into the available space. Adding input switching to Currawong amplifier I am currently building a Currawong valve amplifier (November 2014-January 2015; siliconchip.com. au/Series/277) with the added remote board, and I propose to add the 3-input Selector board from the Ultra-LD preamp of January 2012 (siliconchip.com. au/Article/821). I note that you still sell the PCBs for both projects. Can I select the input channel with the version of the PIC chip software supplied for the Currawong remote? Thanks in advance for your help. (G. D., Melba, ACT) • Yes, this should work as the 3-input selection is already integrated into the Currawong remote control software. Instead of soldering the three 10kW resistors to CON13, fit the box header and run a ribbon cable to the 3-input Selector board. Make sure that pin 1 on the cable is in the correct position at both ends. Senator speakers built using thicker MDF I have been looking through back December 2021  109 issues at your different speakers and would love to build your Majestic speakers (June-September 2014; siliconchip.com.au/Series/275), but that was vetoed. So on to the Senators (September-October 2015; siliconchip. com.au/Series/291). How critical is the internal volume? The plans call for 18mm MDF but I have two sheets of 20mm MDF that have been lying around for years. Therefore, the internal dimension will be reduced in one direction by 4mm, the volume reduction being 0.865L (4mm × 726mm × 298mm). Will this make a noticeable difference, or should I add 4mm to the relevant panels? Hopefully I will still be able to use just one sheet! (M. D., Paynesville, Vic) • Using 20mm MDF will probably make almost no difference. The original box was actually a Bunnings kitchen cabinet kit, to make it easier for amateurs who might not have the skills or tools to cut and join MDF accurately. The material was melamine-coated, pre-cut and drilled. It’s hardly a precision design, and should forgive you for that difference of less than one litre. Soft-starting a large induction motor I have a single-phase 1500W induction motor powering a dust extractor which has been causing overload problems at startup. I recently discovered your Soft Starter article (April 2012; siliconchip. com.au/Article/705), and it appears to be rated for steady-state loads up to 10A (2300W), which suggests it could be a possible solution. However, I note that most of the ‘inrush’ currents described in the design article are very large currents (200A) but very short periods (milliseconds). On the other hand, this motor seems to induce a startup current of around 25A that lasts for about 1-2 seconds. The thermistor specified in the article, the SL32 10015, is rated for a steady-state current of 15A, but I can’t find any clarification on whether this 1-2 second startup period should be considered a ‘steady state’ load. Should it be able to cope with the longer startup draw of such a motor? (Rowan, via email) • The motor startup current is not a 110 Silicon Chip steady-state load by definition. 25A for 1-2 seconds is quite a significant energy pulse, though. Unfortunately, the thermistor data sheet doesn’t provide a curve showing its current handling vs pulse length to allow us to determine if that is safe. Note that the MS32 10015 is a larger version of the SL32 10015 and is more likely to survive that sort of punishment. We do not recommend using this simple type of Soft Starter for a large induction motor because they draw a high current at startup to get up to speed. Their rotational speed is related to the mains frequency, but the Soft Starter will not affect the applied frequency. Also, in your case, the motor starts up under load. You really need a variable frequency drive (VFD) to smoothly ramp up a large induction motor like that. Our 1.5kW Induction Motor Speed Controller design from April & May 2012 (updated in December 2012 & August 2013) can do that – see siliconchip. com.au/Series/25 If you decide to build it, consider using the upgraded 30A bridge, available from our website at siliconchip. com.au/Shop/7/2814 Note that the IGBT bridge used in that design is no longer being manufactured, so you could have difficulty sourcing it anywhere else. Our VFD (IMSC) supports automatic ramping up and down, so you do not have to adjust the speed manually each time. It is an expensive solution, but there isn’t any other practical way of controlling a large induction motor. Small induction motors like shaded pole motors used on fans can be softstarted with a thermistor. As the motor gets larger, you run into the fact that it needs a large amount of energy to spin up and that isn’t easily spread out over a longer period without changing the supply frequency. In theory, if you had enough thermistors in series/parallel it could work, but the startup time could be quite long. You could use our Soft Starter circuit, but it would need to be housed in a larger box with a bank of off-board thermistors connected to the board using mains-rated wiring. A set of four such thermistors in series/parallel would handle four times the total energy, but we aren’t sure if that would be enough for your Australia’s electronics magazine application. Multiple rapid starts might lead to failure. Absent is a proper curve in the data sheet, the only way to find out for sure is to try it. Circuit to detect white ants One of Australia’s biggest but smallest pests is the white ant. Rarely seen, but highly destructive. A proud and meticulous homeowner may not even notice the first hint of their activity. What they need is a monitoring system or even a small handheld device that could be used like a stethoscope. Touch the target area with a microphone probe attached to a finely tuned and filtered amplifier, and listen for the sound of your house being devoured by thousands of tiny teeth. (P. S., Whitsunday, Qld) • Have a look at the Electronic Stethoscope we published in August 2011 (siliconchip.com.au/Article/1119). It should be suitable to listen for white ants, especially in the quiet of the night. The PCB is available from our Online Shop (siliconchip.com.au/ Shop/8/721). Boosting the current from tracking regulators Can you help me? I need a dual power supply of 1.25-25V using LM317T/337T giving at least 2A from both rails. I have looked on the web but could not find anything specific. (R. M., Melville, WA) • The LM317 and 337 are rated at 1.5A maximum. However, higher-current equivalents are available. For example, the LT1085 (positive) and LT1033 (negative) are pin-compatible and rated at 3A. So the simplest solution is to use those devices instead. Another way to do it is to use the LM317 and LM337 with added current-boosting transistors. We showed how to do this in the HighCurrent Adjustable Voltage Regulator article (May 2008; siliconchip.com.au/ Article/1830). That design was only a positive regulator using an LM317, but the same principle could be applied to the LM337 using an NPN transistor (or Darlington) instead. If you use a BD650 Darlington to boost the positive rail, the complementary BC649 could be used for the negative rail. continued on page 112 siliconchip.com.au MARKET CENTRE Advertise your product or services here in Silicon Chip FOR SALE FOR SALE KIT ASSEMBLY & REPAIR LEDsales 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 LEDs and accessories for the DIY enthusiast PMD WAY offers (almost) everything for the electronics enthusiast – with full warranty, technical support and free delivery worldwide. Visit pmdway.com to get started. LEDs, BRAND NAME AND GENERIC LEDs. Heatsinks, LED drivers, power supplies, LED ribbon, kits, components, hardware – www.ledsales.com.au Lazer Security For Quality That Counts... QUALITY LED PRODUCTS + MORE Massive parts clearance sale, limited stock. Go to lazer.com.au ASSORTED BOOKS FOR $5 EACH Electronics and other related subjects – condition varies. Some books may have already been sold. Bulk discount available. All books can be viewed at: siliconchip.com.au/link/aawx Email for a postage quote, quote photo numbers when referring to a book: silicon<at>siliconchip.com.au TRONIXLABS PTY LTD would like to thank all of our customers for their support and feedback. For any enquiries or customer technical support, please email support<at>tronixlabs.com PCB PRODUCTION PCB MANUFACTURE: single to multilayer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.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 KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith: 0409 662 794 keith.rippon<at>gmail.com 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 December 2021  111 Advertising Index Altronics.................................81-84 Ampec Technologies...............OBC Dave Thompson........................ 111 Dick Smith Contest....................... 9 Digi-Key Electronics...................... 3 Emona Instruments.................. IBC Jaycar.............................. IFC,53-60 Keith Rippon Kit Assembly....... 111 Lazer Security........................... 111 LD Electronics........................... 111 LEDsales................................... 111 Microchip Technology.................. 5 Ocean Controls............................. 8 Phipps Electronics...................... 69 PMD Way................................... 111 SC Christmas Decorations......... 79 Silicon Chip Binders.................. 67 Silicon Chip Subscriptions...... 105 Silicon Chip Shop............ 106-107 Switchmode Power Supplies..... 10 The Loudspeaker Kit.com.......... 11 Tronixlabs.................................. 111 University of Southern QLD.......... 7 Vintage Radio Repairs.............. 111 Wagner Electronics..................... 71 Difficulty finding remote for an older project I have recently updated my hifi system, including the addition of the Remote Volume Control & Preamplifier Module (February-March 2007; siliconchip.com.au/Series/55) and the Studio Series Preamplifier (July 2006; siliconchip.com.au/Article/2718). I’m very pleased with the results. Unfortunately, I have not been successful in finding a suitable remote control to use with the project. Merchants do not seem familiar with the recommended Philips RC5 codes, resulting in several universal remotes being purchased and returned as unsuitable. Operating without a remote control is not a big issue; however, I want to switch on the auto blanking function for the LED display, which is quite bright when always on. Can you please help? (G. G., Perth, WA) • Everyone involved in that has since retired, but from what we can see in the article and the source code (which is available), virtually any universal remote control should work with that project. That includes the current Altronics A1012A and Jaycar AR1955 & AR1975 products. You just need to program them with the correct code. The instructions that come with those remotes are generally not terribly helpful as they do not give much information about what each setting does. But based on experience, we think that one of the following codes would likely work: Altronics A1012A: TV code 0088, 0149 or 0169 Jaycar AR1955: TV code 0200 There surely would be other codes that would work; you’d have to look through the manuals for anything that sounds like a Philips product and try those codes. See the October 2021 issue on page 81 for more information on the Altronics A1021A and how its codes correspond to some older remote controls. Sourcing a KDV149 varicap diode I built the AM Loop Antenna & Amplifier from Oatley Electronics (October 2007; siliconchip.com.au/ Article/2398). Over the years, the weather got to it and I had to dispose of it. I now live in a new location on the coast in North Queensland and I want to build up this antenna again, but Oatley no longer have the kit and I can’t find a data sheet for the KVD149. Can you recommend a diode to use? I discovered that NTE618 is a replacement but I can’t find a supplier. Also, the op amp is no longer available, so I plan to use an LM833. (P. C., Balgal Beach, Qld) • The NTE618 is available from eBay at www.ebay.com.au/itm/331706610858 New thermistor for Temperature Switch I built the January 2007 Versatile Temperature Switch (siliconchip. com.au/Article/2109) from a Jaycar kit (Cat KC5381) some time ago. I need to replace the NTC sensor but I am not sure of the correct type to use. Can you please help? (E. A., Jakarta, Indonesia) • The Vishay NTCLG100E2103JB thermistor should be suitable for most automotive uses and is rated up to 200°C. You can get it from element14 (Cat 1164822). Alternatively, for up to 250°C, use the Amphenol TH310J39GBSN, also available from element14 (Cat 2921623). Other suitable parts stocked by element14 are Cats 2921622, 2773999, 2525366, 2771940, 2771941 & 3397782. SC Notes & Errata Tele-com Intercom, October 2021: in the parts list on page 38, one of the alternative transformers for the ringer section is shown as Triad FS24-100-C2 (Mouser Cat 553-FS24-100-C2). This should instead be Triad FS24-100 (Mouser Cat 553-FS24100). Also see the notes on suppressing noise from alternative switchmode power supplies (other than those specified in the parts list) in the Mailbag section of this issue. Hybrid Lab Supply with WiFi, May & June 2021: the optional microSD card socket is the Hirose Electric DM3D-SF, not the Altronics P5717 (an Oupiin part) as specified in the parts list on page 36 of the May issue. The January 2022 issue is due on sale in newsagents by Thursday, December 30th. Expect postal delivery of subscription copies in Australia between December 30th and January 14th. 112 Silicon Chip Australia’s electronics magazine siliconchip.com.au “Rigol Offer Australia’s Best Value Test Instruments” Oscilloscopes NEW 200MHz $649! New Product! Ex GST RIGOL DS-1000E Series RIGOL DS-1000Z/E - FREE OPTIONS RIGOL MSO-5000 Series 450MHz & 100MHz, 2 Ch 41GS/s Real Time Sampling 4USB Device, USB Host & PictBridge 450MHz to 100MHz, 4 Ch; 200MHz, 2CH 41GS/s Real Time Sampling 424Mpts Standard Memory Depth 470MHz to 350MHz, 2 Ch & 4Ch 48GS/s Real Time Sampling 4Up to 200Mpts Memory Depth FROM $ 429 FROM $ ex GST 649 FROM $ ex GST 1,569 ex GST Multimeters Function/Arbitrary Function Generators New Product! RIGOL DG-800 Series RIGOL DG-1000Z Series RIGOL DM-3058E 410MHz to 35MHz 41 & 2 Output Channels 416Bit, 125MS/s, 2M Memory Depth 425MHz, 30MHz & 60MHz 42 Output Channels 4160 In-Built Waveforms 45 1/2 Digit 49 Functions 4USB & RS232 FROM $ 479 FROM $ ex GST Power Supplies 725 ONLY $ ex GST Spectrum Analysers 789 ex GST Real-Time Analysers New Product! RIGOL DP-832 RIGOL DSA Series RIGOL RSA Series 4Triple Output 30V/3A & 5V/3A 4Large 3.5 inch TFT Display 4USB Device, USB Host, LAN & RS232 4500MHz to 7.5GHz 4RBW settable down to 10 Hz 4Optional Tracking Generator 41.5GHz to 6.5GHz 4Modes: Real Time, Swept, VSA & EMI 4Optional Tracking Generator ONLY $ 749 FROM $ ex GST 1,321 FROM $ ex GST 3,210 ex GST Buy on-line at www.emona.com.au/rigol Sydney Tel 02 9519 3933 Fax 02 9550 1378 Melbourne Tel 03 9889 0427 Fax 03 9889 0715 email testinst<at>emona.com.au Brisbane Tel 07 3392 7170 Fax 07 3848 9046 Adelaide Tel 08 8363 5733 Fax 08 83635799 Perth Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au EMONA