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Shop the catalogue www.jaycar.com.au 1800 022 888 Contents Vol.32, No.12 December 2019 SILICON CHIP www.siliconchip.com.au Features & Reviews 14 The Electrical House of Horrors We’ve found some absolute death traps in electrical equipment imported from, or available, overseas. You can’t be too careful! – by Dr David Maddison 46 Toyota’s Hybrid Synergy Drive: it’s brilliant! An in-depth look at arguably the world’s most successful hybrid motor. It’s often misunderstood but it’s very, very clever! – by Roderick Wall 70 Review: the new Altium Designer 20. We love it! Australia’s world-class Altium Designer has a brand new version for 2020 – we put it through its paces here at SILICON CHIP – by Tim Blythman Australia’s strict electrical laws should keep you safe from dodgy products. But what about the stuff you buy direct from overseas? – Page 14 94 Review: Ausdom ANC7S Noise Cancelling Headphones Just in time for Christmas! These rechargeable Bluetooth headphones feature active noise cancellation technology and great sound quality – by Nicholas Vinen Constructional Projects 24 Have you got a dumb battery charger in your garage? Simple car battery chargers can cook your car battery because they’re d-u-m-b! This simple add-on project will ensure that won’t happen. Suits lead acid, SLAs and even LiFePO4 rechargeables – by John Clarke 38 Altronics’ new MegaBox V2 Arduino Prototyping System With a second set of shield headers, more relays and a whole lot more refinements, the new MegaBox makes prototyping with the Arduino a breeze – by Tim Blythman Don’t throw out your battery charger just ’cos it’s dumb! Make it real smart with our 12V Battery Charger Controller! – Page 24 If you’re into prototyping with Arduino, you should be into the new Altronics MegaBox V2 – Page 38 61 Our new FM Radio Receiver – construction & alignment With FM radio now available just about everywhere, this DIY FM receiver is creating a lot of interest. It’s not difficult to build or align – and this final instalment even has a mini oscillator to build which will help you do just that – by John Clarke 86 High performance linear power supply – part three In this final part of our 45V, 8A linear supply we fit it in its case and mount all the parts – then set it up ready for use – by Tim Blythman Do you understand how Toyota’s very clever Hybrid Synergy Drive works? Very few people do! – Page 46 104 A Christmas Light Display for less than $20.00 Imagine a LED lighting display with infrared control and pattern changing, where all you have to do is solder four wires! Imagine no longer – by Ross Tester Your Favourite Columns 76 Serviceman’s Log Two devices what failed th’idiot test – by Dave Thompson 96 Circuit Notebook (1) (2) (3) (4) Dot-matrix scrolling LED display Hearing loop receiver for Android phones Discrete switching LED driver Low voltage three-phase motor speed controller This month we finish off our new Super-9 FM receiver with the case and alignment – and there’s a simple FM alignment oscillator to make     it really easy! – Page 61 100 Vintage Radio Ferris 106 “portable”/car/home radio – by Associate Professor Graham Parslow Everything Else 2 Editorial Viewpoint 4 Mailbag – Your Feedback     85 Product Showcase 106 Ask SILICON CHIP 109 111   112 112 SILICON CHIP ONLINE SHOP Market Centre Advertising Index Notes and Errata Altium’s new EDA software for 2020. It is even better than AD19, and we loved that! Read our review starting on Page 70 www.facebook.com/siliconchipmagazine SILICON SILIC CHIP www.siliconchip.com.au Publisher/Editor Nicholas Vinen Technical Editor John Clarke, B.E.(Elec.) Technical Staff Jim Rowe, B.A., B.Sc Bao Smith, B.Sc Tim Blythman, B.E., B.Sc Technical Contributor Duraid Madina, B.Sc, M.Sc, PhD Art Director & Production Manager Ross Tester Reader Services Ann Morris Advertising Enquiries Glyn Smith Phone (02) 9939 3295 Mobile 0431 792 293 glyn<at>siliconchip.com.au Regular Contributors Dave Thompson David Maddison B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Geoff Graham Associate Professor Graham Parslow Ian Batty Cartoonist Brendan Akhurst Founding Editor (retired) Leo Simpson, B.Bus., FAICD Silicon Chip is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 626 922 870. ABN 20 880 526 923. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Subscription rates (12 issues): $105.00 per year, post paid, in Australia. For overseas rates, see our website or email silicon<at>siliconchip.com.au Editorial office: Unit 1 (up ramp), 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 139, Collaroy Beach, NSW 2097. Phone (02) 9939 3295. E-mail: silicon<at>siliconchip.com.au ISSN 1030-2662 * Recommended & maximum price only. Printing and Distribution: Editorial Viewpoint Toyota deserves praise for innovation We have an interesting article on Toyota’s Hybrid Synergy Drive system starting on page 46 of this issue. While this system has been around for just over 20 years now, it is still very much current; just recently, Toyota (finally) released the hybrid RAV4 in Australia, and it has (predictably) been selling very well. One wonders what took them so long. Still, I have to give credit to Toyota for not only popularising hybrid drivetrains but also perfecting them and bringing them to the masses. Not only that, but they have been able to fit these complex systems into a range of vehicles, without charging a huge premium to do so. And despite this complexity, Toyota’s hybrid systems are very reliable. Perhaps even more reliable than traditional engines! That’s quite an achievement. Keep in mind that Toyota has a reputation for outstanding reliability, in part because their engineering is so conservative. They’re not a company known for rushing new technology into production, with the high likelihood of early failures, like some other manufacturers. That makes the fact that they have been so innovative in the drivetrain field even more impressive. I think many electronics enthusiasts must also be fascinated with mechanical engineering. There are many parallels between the two disciplines, especially in the automotive field. And of course, the hybrid system brings the two together, combining electric motors, inverters and batteries with internal combustion engines, transmissions, gears etc. Part of what makes Toyota’s system so brilliant, and I think better than any other hybrid drive system, is the way it uses the “Power Split Device” to eliminate the need for a traditional transmission. This simple (and thus reliable) mechanical device is responsible for proportioning and directing energy between the petrol engine, electric motors and wheels. Read our in-depth article for a full explanation of how it works. Of course, there’s a lot of talk lately about pure electric vehicles, and more models are being released all the time. But Toyota has managed to sell more than 10 million hybrid vehicles worldwide, while EV leader Tesla has yet to sell one-tenth of that (admittedly, in a somewhat shorter timeframe). And one significant advantage that hybrid vehicles have is that their much smaller battery pack is not only cheaper, but it uses fewer resources to manufacture. So the same quantity of rare earth metals can go into manufacturing dozens of hybrids compared to just one EV. Plus the onboard internal combustion engine and liquid fuel source make ‘range anxiety’ virtually non-existent. In fact, with their great fuel economy, hybrids can have an even better range than purely internal combustion-engined vehicles. And with the advent of plug-in hybrids, you even have the option of using it as a pure EV for short trips (eg, driving to-and-from work), while still being having a longer range when needed. I hope that other manufacturers begin adopting Toyota’s approach of offering a hybrid version of virtually every model that they sell. It gives consumers the option of spending a little bit more money to get lower fuel use and a greater range. There are many more hybrid vehicles available overseas, which surely will become available in the Australian market soon. Nicholas Vinen 24-26 Lilian Fowler Pl, Marrickville 2204 2 Silicon Chip Australia’s electronics magazine siliconchip.com.au MAILBAG your feedback Letters and emails should contain complete name, address and daytime phone number. Letters to the Editor are submitted on the condition that Silicon Chip Publications Pty Ltd may edit and has the right to reproduce in electronic form and communicate these letters. This also applies to submissions to “Ask Silicon Chip”, “Circuit Notebook” and “Serviceman”. Mission Impossible style electronic exploits Dr David Maddison’s Cyber Espionage articles (September & October 2019; siliconchip.com.au/Series/337) reminded me of a “freeze-frame” machine I built. One Hollywood or “Mission Impossible” style antic is to capture the signal coming from a CCTV camera cable, then display it in place of the original signal. This will supposedly make the security guard in the control room think that nothing is happening, while your crew makes off with the crown jewels etc. My design is probably not suitable to be published as an article in Silicon Chip magazine. But I think it’s quite an interesting circuit and so some of your readers might like to see how I did it, and read about the history behind it. So I’ve put together a PDF detailing the device at: siliconchip.com. au/link/aax1 Dr Hugo Holden, Minyama, Qld. Adding memory to a Micromite It was very pleasing to read the letter from Steve Matthysen on pages 10 & 12 of your November 2019 issue, praising the Micromite modules. As one of the development team members for the Explore 100, Explore 64 and Explore 28, it is heart-warming to have feedback like that. We just set out to make something that was powerful, easy to use and affordable. Steve asked about external memory. Several types of memory are supported, from the standard I2C EEPROM series, to the W25Q series of SPI memory and my favourite: UNIO memory devices. Geoff Graham wrote a CFUNCTION to access UNIO memory, and you can read about this by opening the PDF file in his MMBasic download, “Embedded C Modules/UNIO.ZIP”. These are made by Microchip and are available in many footprints: DIL, SOIC, TO-92, SOT-23, MSOP and CSP. They consume just 1µA of standby current, 5mA when writing, and only cost about 30¢ each! I use the 16Kbit (2KB or 2048 bytes) versions, but you can get smaller capacities if you want. I prefer to have more space than I need, rather than finding out later I don’t have enough. And for 30¢, you can hardly complain. You only need one wire for data transfers, so you only sacrifice one We Stock 1000’s of Plastic Parts for Industry Silicon Chip Suggestions for improving Linear Bench Supply It is good to see the eventual publication of the promised 45V 8A Linear Bench Supply, starting in your October 2019 issue (siliconchip.com.au/ Series/339). However, I think a bench supply should have more protection than your published design. Most commercial bench supplies also lack these components, and it is difficult to add them internally and messy to do so externally. The good thing about home-made electronics is that they can be modified and repaired more easily. Available from Hi-Q Electronics Limited sales<at>hiq.co.nz • Nylon Fasteners • Screws & Nuts • Washers & Spacers • Rivets & Clips • PCB Hardware • Caps & Plugs • Knobs & Handles • Hole Pugs & Bushes • LED Mounts & Light Pipes • Cable Ties & Mounts 4 Micromite pin to have a full external memory. You can also have two devices on the same pin, giving up to 32Kb (4KB) of storage per I/O pin. Need more? Just use another pin and another couple of 11AA devices. And if all that is not impressive enough, they have a read/write endurance of one million cycles and data retention of 200 years. Anyone wanting to know more should read the UNIO PDF in Geoff’s MMBASIC download. Graeme Rixon, Rictech Ltd. Dunedin, NZ. NZ 0800 800 293 www.hiq.co.nz Australia’s electronics magazine siliconchip.com.au Silicon Chip--mouser-selection-in-stock-205x275.pdf 1 8/10/2019 2:16 PM C M Y CM MY CY CMY K siliconchip.com.au Australia’s electronics magazine December 2019  5 At some stage, it is quite likely that a higher voltage will be required than the bench supply can provide, so another bench supply or DC power source will be added in series. Or the bench supply could be used to charge a battery bank, where there could be a possibility of the battery being connected in reverse. In the case of a series connection, if one power supply becomes overloaded, this can result in a reverse voltage being applied to the output of the other supply. I have witnessed this first-hand! To prevent damage to the supply, an appropriate-size fuse in series with the output (eg, 10A) should be used. This should be combined with an associated reverse-polarity diode of sufficient current rating (eg, an MR756) on the power supply side of the fuse will protect the supply. Then, all that will be damaged in the case that a reverse voltage is applied will be the fuse. Also, when charging batteries, it is sometimes desirable to add a series diode such that accidental battery reversal needs no damage control. Also, if the mains power fails or the supply is turned off, then the batteries can stay connected without discharging. The downside to the diode is the forward voltage variations due to load current change. This can be a problem for batteries with a small number of cells where precise voltage termination is critical. A second positive output terminal with an internal series diode could be included for battery charging purposes but doesn’t have to be used. I don’t like using ‘dangling’ diodes. This is the beauty of manufacturing my own power supply; I can incorporate these changes during construction. This power supply project has given me some enthusiasm to experiment. I built your High Power DC Motor Speed Controller (January & February 2017; siliconchip.com.au/Series/309) and added a series inductor and electrolytic filter capacitor to make a basic switchmode power supply. I set the frequency to around 220Hz and isolated the control circuitry with its own power source. I am feeding the Mosfet power board from a rectified 36V 8A source and intend to upgrade the Mosfets and diode to handle 100V. I had no luck with using the feedback system to try 6 Silicon Chip Australia’s electronics magazine to regulate the output voltage, so am going to try using as op amp feeding into the speed control input. The inductor I used is an old TV E/I transformer rewound with a 5A wire, measuring 11mH. I used a 10,000µF 100V electrolytic capacitor. The ripple at full load is relatively insignificant. I may try using a different inductor and adjust the switching frequency to 1kHz. 48V off-grid power systems are becoming quite popular now, and I wish to upgrade my 24V system. I have all the necessary parts to do so, except my Engel-style fridge runs off 24V DC and I have alarm systems and other loads that use 12V. There is an abundance of 24V-to-12V converters, but I haven’t found a 48V to 24V or 12V converter yet! So the above experiment may become of some use. T. C. Thrum, Para Hills West, SA. A handy trick for linear power supplies It is great to see the 45V 8A Linear Bench Supply project (siliconchip. com.au/Series/339) by Tim Blythman in the October issue (no micro! – tongue in cheek). One way to expand the safe operating area and limit heat dissipation in the regulator transistors is to pre-regulate the transformer primary. The DC supply to the regulators only needs to be adequate to keep them in regulation at the required output voltage. To calculate the minimum acceptable input to the regulators, you need to add the regulator drop-out voltage and maximum supply ripple. I have done this in the past at up to 40A for low-voltage electrolysis applications. You can do this with a Triac phase-control module that uses either a voltage-controlled input or potentiometer. Surprisingly, you do not need a complex error amplifier; a simple opto-isolator will do the job. Of course, proper snubbing is required as on the primary side of the transformer, you are chopping mains voltage, but it is not that onerous. This technique was developed in the days before reliable and cheap switchmode supplies, when we needed to supply say 35A at 5V for 10 boards full of TTL logic chips, plus a microcontroller and memory (1982). It was needed to keep the power supply dissipation reasonable. One of the electron microscope lens siliconchip.com.au ALL OPTIONS. ONE PRICE. LIMITED TIME. COMPLETE SOLUTIONS. 0 June 2020 3 Until 31 December 2019 you can buy high quality Rohde & Schwarz spectrum analyzers, power supplies, power analyzers and oscilloscopes from our Value Instruments range fully optioned with big cost savings. Value Instruments from Rohde & Schwarz are precise, reliable and universal measuring products that are easy to use and combine practical features with excellent measurement characteristics. Designed for users who want high quality products at a good price. More information about our range is available online at: https://www.rohde-schwarz.com/complete-promotion Contact: sales.australia<at>rohde-schwarz.com siliconchip.com.au 1911 Silicon Chip full page Value Inst 181x244 New .indd 1 Australia’s electronics magazine December 2019  7 4/11/2019 4:45:10 PM Helping to put you in Control PID Temperature Controller New compact sized PID temperature controller with vivid LCD display, auto tuning PID, soft start and ramp and soak. Input accepts thermocouples J, K, T and Pt100 sensors. Pulse and Relay outputs. SKU: NOC-330 Price: $295.00 ea + GST Energy monitoring module The TCW260 features galvanic isolated digital inputs, analog inputs, and RS-485 interface and has Ethernet connectivity. Also has datalogging and alarming SKU: TCC-026 Price: $409.95 ea + GST DigiRail Connect RAMIX Features both a Modbus TCP and Modbus RTU communications and has 2 universal analog inputs, 2 analog out, 4 digital input and counter (32bit) and 2 relay out. It can also operate as a Modbus TCP to RTU gateway. SKU: SIG-120 Price: $399.95 ea + GST Temperature & RH Controller 24 V Panel mount temperature & relative humidity controller with sensor probe on 3 metres of cable. 2 independent relay outputs. 12 to 30 VAC or DC powered. SKU: CET-108 Price: $209.00 ea + GST UC1414 4G SMS Controller This controller has 2 digit inputs and 2 relay outputs. SMS messages can be sent to up to 6 phone numbers on change of state of an input and the operation of the relays can be controlled by sending SMS messages from your mobile phone. SKU: ULC-005 Price: $259.00 ea + GST Eight 12VDC Relay Card Eight channel relay card with flexible inputs. Each relay is rated to 7 A at 240 VAC, 10 at 28 VDC. Operates from a 12 VDC supply on DIN rail mount. SKU: RLD-128 Price: $109.95 ea + GST T7 Data Acquisition Module Comes with 14 high speed analogue inputs, 20 Digital I/O, Ethernet and USB Connectivity. SKU: LAJ-045 Price: $615.00 ea +GST For Wholesale prices Contact Ocean Controls Ph: (03) 9708 2390 oceancontrols.com.au Prices are subjected to change without notice. 8 Silicon Chip power supplies we use these days is rated for 60A at 30V DC; it is a switchmode type for efficiency. The multistage mains input filter section takes up one-third of the lunchbox-sized enclosure. An alternative to the Triac approach is to use Mosfet-based PWM control of the primary. I have designed a 20kHz switching “electronic variac”. Thus you get 50Hz controlled output voltage without the chop of Triac phase control. I used a linear voltage-controlled mark space with just a dual comparator and a fancy opto-isolated gate driver chip with two power Mosfets (yes, no bridge rectifier). By chance, I discovered a very nice range of French-made dual-winding board-mount fully certified 5W mains isolation transformers (RS-AU) to supply the drive voltages for this circuit. Thus, for $5, you have a fully-isolated transformer supply for the PWM circuit and a separate supply voltage for gate drive. The challenge is to design the output filter to stop inductive ringing from causing destructive spikes at the transformer primary. If not controlled, these risk both transformer insulation breakdown or destruction of the switching Mosfets. Like all these types of efforts, it is a design compromise. Thank you for helming such a great magazine. If you are interested in what we do with electron microscopes, see: https://microscopy.unimelb.edu.au/ home#electron-microscopy Roger Curtain, Williamstown, Vic. Confusion over PV inverter anti-islanding Thank you for your great magazine. I’ve been a reader for many years, and the quality articles keep getting better! Your readers may be interested in a little problem I had of late. Our PV system (comprising 16 panels, each with a micro-inverter) recently came due for its five-year compliance test involving, amongst other things, an anti-islanding test. Two electricians separately tested the system one week apart. Electrician A said the system failed the test while electrician B passed it. Anti-islanding is an inverter feature which ensures that, in the event of a blackout, the output of the PV system is not fed back to the grid, where it would be hazardous to linesmen workAustralia’s electronics magazine ing to fix the blackout. Test documentation states that the PV inverter(s) must cease to export energy to the grid within two seconds of loss of mains power. Electrician A measured the “time to disconnect” of our PV system at eight seconds where Electrician B measured it at less than one second. Both electricians repeated the test to confirm their results. I noticed that both electricians used a standard voltmeter to measure the voltage on the PV side of the “Solar Supply Isolation Switch”. However, to cut mains power to the PV system, Electrician A used the “Solar Supply Isolation Switch” while Electrician B used the “Mains Supply Isolation Switch”. Why the different outcomes? Is our PV system compliant or not? Interestingly, test procedure documents from two authorities do not agree on which switch should be used to disconnect mains power to the PV system during the test. EvoEnergy (siliconchip.com.au/ link/aawz) specifies the “PV array main switch” (which we assume to be the “Solar Supply Isolation Switch”) while AusNet Services specifies the “Main Supply isolation Switch” (siliconchip.com.au/link/aax0). In discussions with the electricians, it was agreed that the inverters were indeed shutting down in response to the loss of mains; however, the PV system might be retaining some energy within capacitive or inductive components during the shutdown process. In test B, this energy would be quickly absorbed by household loads that remained connected to the PV system. Test A instantaneously isolated the PV system from all loads, thus providing no path for the residual energy to be dissipated, resulting in a prolonged decay in the measured PV output voltage. I’d be interested in comments from the electrical engineers amongst your readers. The reality is, if our PV system is indeed defective, we are up for an expensive repair bill. Other PV system owners may well face the same problem. Steven Ring, Hackett, ACT. Response: we think that your system is compliant; however, it would be good to have official clarification of siliconchip.com.au the test procedure. If you think about it, neither test is actually a realistic way to simulate a blackout. After all, during a blackout, your system is still connected to the grid; it’s the primary sources of power for the grid which are disconnected. Simulating that would be very difficult. The closest you could probably come is to disconnect your premises from the grid. Hence, we think that the method suggested by AusNet and used by your Electrician B (which indicated compliance with the regulations) is the best choice. everywhere. What about hills? Even of the advantages of using such a high a small one could be enough to block frequency is that 1500MHz of bandsuch a short-range signal. width for each direction is available. And then there are walls. Notice that So, taking all of the above into acin that video, the base station is visible count, most of the time these new, exthrough the window and is not far from pensive 5G mobiles will switch to 4G the cell, and the signal goes through or even 3G because these are the only a wall to a modem/router which then signals which reach them. repeats the signal using WiFi which Fibre to the premises can be easily has better wall penetration. What pro- upgraded to similar high speeds, and portion of houses are set up to allow doesn’t suffer from any of the above this? What would have happened if range or coverage problems. Also conthe cell tower was on the other side sider that, as the number of 5G users of the building? increases, the speed will drop because They frequently show base stations the bandwidth must be divided beon power poles on street verges, pre- tween users. 5G is a poor way to sumably because so many of these are So it’s hard to understand why it’s deliver broadband internet required due to the short range. These worth going to the expense of rolling Telstra claims that 5G will mean all need to be connected to the network out 5G networks when so many limiRAYMING better mobile data connections (see TECHNOLOGY via fibre optic cable, presumably those tations will apply. www.telstra.com.au/5g).PCB But Manufacturing many used by the which already go to Finally, I found an ACMA document andNBN PCB Assembly Services of the current demos of Fuyong 5G technolnearby houses. So what’s the point? (http://siliconchip.com.au/link/aawy) Bao'an Shenzhen China ogy are carefully crafted to downplay Telstra maps state “Our maps de- which indicates that Australian telcos 0086-0755-27348087 the downsides of using such high fre- pict approximate 5G coverage only want to use 250MHz per direction in Sales<at>raypcb.com quencies; for example, this video from and do not include indoor coverage. the 27.25GHz band. This is being opAmerican telco Verizon: https://youtu. Speed and performance, and whether posed by NBN’s satellite “Sky muster” www.raypcb.com be/jnyG2bliKCs a 5G device uses the available 5G de- (remote and black spot areas) service The high frequencies are needed pends on network and device interac- and by the CSIRO, because of mutual for such high data rates and to han- tions and prevailing radio conditions interference which will cause errors. dle a large number of users on each at your location.” These errors will slow the overall cell tower. Similarly, Optus states “There may throughput. But how far can these signal expect be technical or other reasons that afAlan Hughes to travel in free air? Around 915 me- fect your ability to access the service Hamersley, WA. tres, ie, less than a kilometre! Note at your address. The service check is that in that video, he had to increase an indication that you are within a 5G On cat deterrents and electronic bugs the receiver height to get line-of-sight serviceable area; it does not guarantee I have a comment on the Serviceback to the base station! that your address is 5G serviceable. We man’s Log column titled “A shockingly And what about foliage and weath- recommend that you position your mo- cute new companion” in your October er? That video was shot on a fine day; dem close to a window to maximise issue. In it, Dave Thompson purchased he makes no mention of what happens signal strength.” a shock mat for training his new cat. I when the foliage is wet, or the signal Currently, ACMA has only auc- find that air freshener dispensers make is attenuated by heavy rain. tioned off 25MHz of bandwidth on for excellent indoor automatic cat deThere’s also the question of terrain. either side of the 3.6GHz bands being terrents. You just need to add some One example in the right location can- used for 5G. The frequencies used by components to trigger the dispenser not be generalised to say it will work Verizon are 10 times higher, and one in the presence of a cat. RAYMING TECHNOLOGY Fuyong Bao'an ,Shenzhen, China Tel: 0086-0755-27348087 email: sales<at>raypcb.com web: www.raypcb.com PCB Manufacturing and PCB Assembly Services 10 Silicon Chip Australia’s electronics magazine siliconchip.com.au ontrol evices Unit 17, 69 O’Riordan Street ALEXANDRIA NSW 2015 AUSTRALIA T: 02 9330 1700 CELEBRATING 21 YEARS OF EXCELLENCE IN ENGINEERING PRODUCTS: JOYSTICKS & GRIPS SIMULATORS USB CONTROLLERS LINEAR SENSORS ROTARY SENSORS TILT SENSORS LEVEL SENSORS PRESSURE SENSORS SENSOR BOXES SWITCHES LED INDICATORS EMERGENCY STOPS KEYPADS & SWITCH PANELS FOOT PEDALS PE FOOT SWITCHES AIR SWITCHES PALM SWITCHES VACUUM SWITCHES PRESSURE SWITCHES MICRO SWITCHES BELL BELLOWS HAND CONTROLS INTERFACE MODULES INCLINOMETERS ACCELEROMETERS DRAW WIRE SENSORS OPTICAL ENCODERS INCREMEN ENCODERS INCREMENTAL MAGNETIC ENCODERS MOTOR CONTROLLERS CUSTOM BUILDS Control Devices offers an extensive range of high-end controllers and electronic components in the market. With our engineering knowledge we aim to provide the best possible technical support and engineering solutions to optimise your operational performance. EXCELLENCE IN ENGINEERING Control Devices Engineering and Production has provided customised solutions for our customers requiring alternative/special controls or interfaces. We undertake projects to replace existing controllers or new concepts from design to finish, ensuring it to be fit for purpose for your application. Contact our team today for more information. OUR PARTNERED PRODUCTS: sales<at>controldevices.net www.controldevices.com.au The best way to do this is to use the cat’s eyes. You can use an infrared illuminator combined with a passive infrared sensor. Cat’s eyes reflect light exceptionally well, so as soon as they look at the sensor, it should be triggered. An alternative is to use a passive radio-frequency identification (RFID) tag embedded into a collar to identify your offending pet. Then you just need to set up your automatic cat training device in the location where the cat is not supposed to be, add a power plugpack and an Arduino to control it all. There are more cat deterrent ideas (mainly for outdoors) in the following YouTube video: https://youtu.be/ uIbkLjjlMV8 I was also interested in the electronic spying articles in the September & October issues (www.siliconchip.com. au/Series/337). But they had nothing to say about sleeping bugs, magnetic limpet GPS vehicle tracking units and smoke alarm bugs. A sleeping surveillance device can sit for two to three years, disguised as say a smoke alarm (most homes by law must have them). Then one day, it gets a blast of RF to wake it up and ‘call home’ like a satellite. It then takes images or records sound in the room and transmits the data before going back to sleep. John Crowhurst, Mitchell Park, SA. Fixing worn carbon contacts in remotes I was in the same boat as M. M. from Croydon Park, SA (Ask Silicon Chip, August 2019, page 107-108); I had trouble with my bathroom heater remote working reliably. After pulling the remote apart, I was confronted with dirty carbon contacts. Not realising the carbon was the contacts, I proceeded to clean the surface, assuming I was going to end up with shiny copper strips. Of course, that didn’t happen, and instead, I ended up with nothing. So I decided to completely remove the carbon contacts, drill holes where they were located and mount tactile switches on the back of the board (Jaycar SP0600, $0.95ea) using hot melt glue. I then drilled small holes and fed tinned copper wire through to connect the switch contacts with the tracks which used to go to the carbon contact patches. It was a cheap fix dollar-wise, but not time-wise. Still, I think my solution will last a lot longer than the carbon contacts did. John Benfer, Upper Caboolture, Qld. Criticism of touchscreens In the Mailbag section of the October issue on page 10, Edison Zhang referred to the problem of his “little fat fingers” when typing in URLs. Well, he is not alone. Except, in my case, I have two hands of thumbs. I keep wondering about the life of the delete and backspace keys on my keyboards since they are used many times more than any other key. Even with a standard-size keyboard, I regularly hit two keys at once or rather clip a key adjacent to the one I want to press. Touchscreens are not a solution and are actually worse to use, so I avoid Who the #?!&*% is… • Operating since 1980. • Contract manufacturer, UL compliant, with engineering capability. • Your products may change but your contract manufacturer doesn’t have to. How to find a reliable contractor! Team up with us for the long haul. • We create a quality plan for every product we make for you. • Contact us for a free quote. www.elfelectronics.com.au 1300 367 353 lorenzo<at>elfelectronics.com.au 12 Silicon Chip Australia’s electronics magazine Take a look into the future www.pcbglobal.com siliconchip.com.au them as much as I can. I realise that Silicon Chip publishes projects that use touchscreens, and I admit that it is an easy way to put functionality into the user interface. But there is a section of the community who find such interfaces awkward to use, and I am one of them. Of course, there are plenty of devices available that use keys and physical switches such as my mobile phone and MP3 player. But their tiny switches become hard to use when I trim my fingernails. George Ramsay Holland Park, Qld. Response: you are right that touchscreens are a compromise. They make it easy to add lots of features to a project with just a single part and a bit of software, and that same screen then comes in very handy for displaying plenty of data. But there are situations in which they are very hard to use, such as in a moving vehicle, or when wearing gloves. While standard keyboards may not be perfect, it is far easier (with practice) to type a lot of information in via such a keyboard than with even the best multi-touch capacitive touchscreen. Hence, our USB Mouse and Keyboard Interface for Micros project in the February 2019 issue (siliconchip.com.au/ Article/11414). Building the Raspberry Pi audio board with different DAC chips I am building the sound add-on for your Raspberry Pi Speech Synthesis project in the July 2019 issue (siliconchip.com.au/Article/11703). In my infinite wisdom, I accidentally purchased some TDA1543A, not TDA1543 ICs. I promptly realised my mistake after they arrived. They are not directly compatible. The main difference is in the digital audio format that they expect to receive. The TDA1543s you specified accept I2S format, which is similar to left-justified (LSB first) except that it is off by one bit. The TDA1543As expect to receive the “Japanese input format” which turns out to be the right-justified (MSB first) format. I figured that it must be possible to make the Raspberry Pi generate the appropriate format of digital audio data to suit these chips, but it took quite a bit of fiddling to figure it out. After some messing around, I made an overlay file which creates an alternate siliconchip.com.au sound device for use with the “dtoverlay” in config.txt. I created the overlay created using the following web page as a reference: http://siliconchip.com.au/link/aax2 Part of the difficulty in getting it right is that the I2S and left-justified formats will work even if there is a mismatch between the number of bits transmitted and those the receiver expects. The number of bits transmitted just needs to be sufficient. However, being MSB-first, the right-justified format requires the exact number of bits the receiver expects to be transmitted. I initially tried using 16-bit frames, and it didn’t work properly. Once I redid the overlay to use 24-bit frames, it finally worked correctly. Other readers may find themselves in the same boat as me, so I’m sending you the revised overlay file. To install it, copy it to the appropriate location like this: sudo cp TDA1543A-SC.dtbo /boot/overlays Then change the line in /boot/config.txt to read: dtoverlay=TDA1543A-SC instead of: dtoverlay=hifiberry-dac Finally, I note that there is a little digital noise getting through into the audio outputs. I can hear when the processor comes off idle. Tom Skevington, Balcatta, WA. Comments: thanks for sending us the file. It is now available as a download on our website, associated both with the original project and this issue. We noticed that a little digital noise was creeping into the audio outputs when developing the project, but found it low enough in level that it didn’t interfere overly with the speech produced. Perhaps you’re using a speaker that’s more sensitive to the noise frequencies. Radio, TV & Hobbies and other old magazines for sale I am looking for people willing to take Radio, TV & Hobbies magazines off my hands for a reasonable price. I also have a copies of Australasian Radio World, Practical Wireless/Television, Short Waves, Radio News, Wireless World and Practical Electronics. These issues of Radio, TV & Hobbies range from 1940, 1944-50, 1952-64. Email for a list of every issue available. Lee Farrar, Victoria karmalee<at>live.com.au SC Australia’s electronics magazine December 2019  13 Buying mains products online? Maybe from markets or “$2 shops”? Beware: a lot of what you’re buying could be a death trap! The Electrical House of Horrors by Dr David Maddison W e take for granted the safety of mains-operated appliances. With few exceptions, anything purchased in Australia from a legitimate retailer can be expected to conform to the appropriate safety standards and therefore be safe to use. Of course, there are still ways to get electrocuted, for example, taking a bath with a toaster or a hairdryer close by is a terrible idea. But you already knew that! The real danger is that you might purchase an appliance which appears to be properly designed and made, and may even appear to have the appropriate approvals and certifications, but it could still be very unsafe. In the worst case, mains voltages may appear where they shouldn’t – in exposed metal that you (or someone else) can easily come in contact with. 14 Silicon Chip Some of these unsafe products may even have a reputable brand printed on them; ie, they are counterfeits. Unfortunately, many overseas countries which are the source of low-cost electronics online have much weaker electrical standards than ours (or none at all!). And they may also have very lax enforcement of counterfeiting or faking of regulatory markings. Many of these dodgy devices find their way to Australia. In this article, we’ll take a look at many device ‘teardowns’ (ie, disassembly) and other investigations of unsafe electrical goods. Many of these have been done by Australians, but some are by people in other countries with similar electrical standards to our own. Many of these teardowns are posted as YouTube videos, so if you want to know more, follow the shortlinks shown. Australia’s electronics magazine siliconchip.com.au    It doesn’t even need to be mains operated to be a real danger. The internet is full of horror stories about rechargeable cells – like this Li-Ion 18650, which is literally exploding. This could be due to poor manufacturing standards or    poor handling (eg, overcharging/discharging, etc). Phone chargers There are numerous cheap (and nasty!) phone chargers on the market and many, if not most, are dangerous. Many people, including at least one Australian, have been electrocuted due to the use of such chargers. You definitely should only use chargers from the original phone manufacturer or reputable after-market manufacturers. Of course, you should not use a mains-powered charger (or any mains-operated devices) in wet areas such as in a bathroom or around a swimming pool or spa. A good exposé of some fake phone chargers is in a video from Australian blogger David L Jones titled “EEVblog #388 - Fake Apple USB Charger Teardown” at: siliconchip. com.au/link/aau7 (see Fig.1). This ‘teardown’ looks at some fake Apple chargers which lack the safety and genuine UL certification of real Apple chargers. He found problems including: • easy-to-remove internals without tools • no full-wave rectifier • very low clearance between mains and low voltage components (‘creepage’ distance) • no isolation slots on circuit board between mains and low voltage • no fuse protection such as fusible resistors or resettable devices • no inductive filters • no insulating layer between primary and secondary circuit boards on one of the devices investigated • small creepage distance between transformer primary and metal shield of USB connector • no snubbers (an energy absorbing circuit element) • no filter capacitor between primary and secondary of the switching transformer on one device • standard capacitor in place of Class-Y safety capacitor between primary and secondary of transformer on one device • no controller IC (not a danger but an indication of a primitive design) • no Mosfet but cheaper transistors in one device The transformer in these devices was not examined, but one can assume that they are unsafe, as has been found in many other similar devices. There were no Class-X or Class-Y capacitors in the counterfeit chargers. These are safety-rated capacitors designed for line voltage use. Class-X capacitors are generally used to suppress symmetrical interference and go across the line, from Active to Neutral. Class-Y devices are used between Active and Earth or Neutral and Earth, to suppress asymmetric interference. A failure in a Class-X device due to overvoltage may result in short circuit, leading to the tripping of a circuit breaker. Class-Y capacitors are designed to fail open-circuit, because if they short circuit, the Earth conductor could become live which would be a real hazard. The following link contains a teardown of a genuine, safe Apple charger. You can see that there is quite a difference from the cheap fakes David pulled apart: www.righto. com/2012/05/apple-iphone-charger-teardown-quality.html Another good video on this subject is titled “DANGEROUS Chinese USB charger (no isolation in the transformer!)”, and you can view it at: siliconchip.com.au/link/aau8 (see Fig.2). Fig.2: in this phone charger tear down by DiodeGoneWild, the only insulation that existed between the primary mains windings and the secondary windings was that provided by the enamel insulation of the wires. YouTuber DiodeGoneWild points out several safety violations. The worst of these is probably that the only insulation between the primary and secondary of the mains transformer was the enamel on the wires. There was no insulating tape layer, as is required for mains transformers. This omission makes it extremely dangerous. General-purpose USB chargers Here we look at some dangerous general-purpose USB chargers, not specifically designed for phones although they can be used as such. See the video titled “Dangerous Chinese Travel Extension with USB Charger – teardown” at: siliconchip.com. au/link/aau9 In it, YouTuber DiodeGoneWild investigates a device for travellers that is available online (Fig.3). It combines an extension cord with a multi-country (including Australia) Counterfeit electrical products Fig.1: underside of fake “Apple” chargers during examination by David L Jones. Numerous safety violations were discovered. siliconchip.com.au Counterfeiting of Australian electrical hardware (and other products) is a serious problem, and the counterfeit products are generally substandard, and possibly dangerous. One Australian manufacturer of electrical hardware makes a relevant statement on their webpage, at: siliconchip.com.au/link/aaua Australia’s electronics magazine December 2019  15 Fig.3: YouTuber DiodeGoneWild investigating a dodgy combined USB charger/mains power extension cable with numerous safety problems. Fig.4: bigclivedotcom looking at a transformer with failed insulation due to poor quality control. This fault could have lead to electrocution. grounded outlet and four USB charging sockets. Even though it has a grounded outlet, the device’s plug only has two pins. It also has a cartoon character on it, making it attractive for children to play with. The investigation revealed the following problems: and many of these are quite acceptable for beginner use. A general warning: only those produced by a reputable manufacturer should be used to measure mains or high voltages. Some are not safe at the voltages that they claim to be able to handle. Some also falsely claim to have a fused input. There can also be significant safety and quality variations between samples of the same model; they can have completely different internals despite a similar or identical external appearance. One reason for this is that some might be genuine products, and others might be fakes. See the video titled “Tiny $2 Multimeter with 1000V Range! Test with Smoke” at: siliconchip.com.au/link/aauc by YouTuber DiodeGoneWild. This shows the internals of a US$2.20 analog multimeter (Fig.5). It was rated at 1000V and yet had no fuse, close PCB track spacings, the probes came out easily and it used tiny surface-mount resistors. It’s only safe for use at low voltages. Another video by the same author titled “$3 multimeter test & teardown” can be seen at: siliconchip.com.au/link/ aaud This is another cheap digital multimeter, commonly available on eBay, which cost US$3, including delivery to Europe. Safety violations discovered included: • certain plugs could be inserted with one pin in the device and another outside, thus leaving a live exposed pin • a very thin mains cable that could not safely carry the current claimed • the case was easy to disassemble without tools, including by a child, exposing live components • the USB power supply had areas of inadequate separation between tracks and also had regular capacitors in place of Class-Y safety capacitors • the USB output failed after 3A current draw for 30 minutes (it was rated at 4.8A) • children’s fingers could fit into the mains power outlet sockets • components on the charger board were running beyond their maximum design power. The transformer itself was not examined, but we would not be surprised if it has inadequate insulation between its primary and secondary. Another relevant video is “Horrific USB power supply fault. (Electrocution risk.)” at: siliconchip.com.au/link/ aaub by YouTuber bigclivedotcom. This video shows a USB charger that was live with mains voltage on the USB outlet side. The fault was found to be related to a defect in the insulation between the primary and secondary of the transformer (see Fig.4). Bargain multimeters: unsafe at any price! There are many cheap multimeters available on eBay, Fake UL, CE and other certifications It is easy to print a certification label on a product, but that does not mean that it has been certified. UL, formerly Underwriters Laboratories (www.ul.com) is a US certification agency with branches in 46 countries, including Australia. Their trademark is widely (but falsely) applied to non-approved items. CE or Conformité Européenne (siliconchip.com.au/link/aaup) is another mark that is widely faked. Correctly applied, it designates compliance with European standards. 16 Silicon Chip • no fuse or high-voltage resistors • a resistor divider for measuring high voltages made using small surface-mount resistors • there is a space for a fuse on the circuit board but none is fitted • writing on the meter case refers to the non-existent fuse • the peak AC voltage on the rectifying diode can exceed the diode’s rating of 1000V • there are no internal protection components The investigator compares this meter with another one (Left): this is the voluntary UL mark for Australia. According to UL, “the UL-AU Mark can be used for a variety of products including residential smoke alarms, fire alarm panels, spa and swimming pool equipment, and lighting products.” Australia’s electronics magazine (Right): the often-faked Conformité Européenne trademark. (Left) these are two of many UL marks available. They’re also widely faked. siliconchip.com.au Fig.5: the PCB from a cheap analog multimeter, rated at 1000V. It has no fuse, narrow PCB track spacing and tiny surface mount resistors, making it inappropriate for use at such a high voltage. he already had with the same model number, and discovered that his older one has utterly different internals and also has a protective fuse and much bigger resistors (see Fig.6). The original is also labelled CAT 1 for its voltage rating, unlike the unit being studied. CAT 1 means that it is for use with devices that are not connected to mains; an honest rating for the original meter. But this label was lacking on the new device. The new meter also has a CE mark indicating European certification, but that is unlikely to be the case. The meter is OK for a beginner but should not be used on any mains or other dangerous voltages. See also the follow-up called “$3 multimeter - high voltage & overcurrent test (smoke and explosion)” at: http:// siliconchip.com.au/link/aaue One very popular low-cost multimeter is the DT-830 series meter, available under many different brands and variations. Like other cheap meters, it’s not suitable for highvoltage or high-current measurements. This meter is also available in kit form. The kit costs more but unlike most of the pre-built versions, has a fuse and uses through-hole resistors. There is an extensive web page describing one version of this meter, the DT-830D at: siliconchip.com.au/link/aauf Fig.7: YouTuber AintBigAintClever demonstrates that the exposed terminals of a mains-operated ‘corn cob’ LED light carry dangerous voltages and currents. The meter indicates a power of 31W and a current flow of 158mA simply from contact with the light. siliconchip.com.au Fig.6: DiodeGoneWild comparing two multimeters with the same model number; the older meter is on the left. Even though they are almost identical externally, the internals are very different. The older meter has a fuse, appropriately sized resistors for higher voltages and is correctly labelled as CAT 1, meaning not suitable for mains connected circuits. Dangerous lights Lights can be a particular safety concern. While current Australian regulations require power outlets to be protected by RCDs, until recently, lighting circuits were not required to have an RCD. If you have an older house without RCD protection of lighting circuits, you may wish to consider installing such protection, and you certainly should have a “safety switch” fitted if you don’t have one at all. A video titled “Dangerous LED “corn cob” lamp test and teardown” can be seen at: https://youtu.be/n3ci4nlKhEk In it, YouTuber “AintBigAintClever” looks at a mainsoperated ‘corn cob’ LED light and finds live voltages on the surface of the device, an obvious shock or electrocution hazard (Fig.7). That video was made in 2014; the corn cob lights available online today appear to mostly have a plastic insulating cover over the LEDs to render them safe. But some of these unsafe devices may still be in service. Note also that this video is from the UK, but we use the same BA22d bayonet fitting at similar voltages. Another video by YouTuber bigclivedotcom, titled “126 LED hydroponic death lamp.” can be seen at: https://youtu. be/QRNYDLp4zdM Fig.8: a mains-derived 49.5V appears at the exposed face of this lamp; a potential shock hazard, as its internal power supply is not isolated from the mains. Australia’s electronics magazine December 2019  17 Fig.9: a teardown and investigation by YouTuber bigclivedotcom of a fish tank light that killed all the fish. This investigation revealed that the 126-LED hydroponic lamp did not have an isolated output, and if a person or plant made contact with the exposed connections, they could receive a shock (Fig.8). Fig.10: a selection of electrode boilers available online, including one sold as a baby bath heater, as looked at by YouTuber bigclivedotcom. Warning! Do not use such devices. They are extremely dangerous. An aquarium light . . . that killed fish able which are exceptionally dangerous because users can come into contact with the electrodes. In the video titled “2.5kW electro baby-cutor. (And dodgy bucket warmer.)” at: siliconchip.com.au/link/aauh YouTuber bigclivedotcom looks at a variety of these units, including one sold as a baby bath water heater (see Fig.10). In another video titled “EEVblog #873 - World’s Most Dangerous Consumer Product!” at: siliconchip.com.au/ link/aaui David L Jones investigates a dodgy water heater he purchased for $3.89 from Hong Kong (Fig.11). Another video called “Suicide Water Heater & Deadly Experiments (Gone Too Far)” at: siliconchip.com.au/link/aauj sees YouTuber DiodeGoneWild testing the limits of another such device by adding salt to the water, with disastrous results (see Fig.12). This could happen under ordinary circumstances. Not even fish are safe from dangerous electrical appliances. YouTuber bigclivedotcom investigated an aquarium light that killed all the fish in the tank (Fig.9). He called the device the “fish-o-cutor”. It could kill people too if placed in a bath, hot tub or swimming pool. See the video titled “Pink plastic LED fish-o-cutor.” at: siliconchip.com. au/link/aaug The device came with false certifications such as CE and a double-insulated marking, but it had continuity between the low voltage outlet of the device and the mains input Neutral terminal. The fault which killed the fish was traced to electrical leakage from the light in the aquarium, through the frame to Earth. Direct water heaters (electrode boilers) An electrode boiler or heater is a device that heats water using two electrodes (for single-phase mains), heating the water between the electrodes by passing current through it. This relies on the water not being pure and therefore conducting electricity. This is a legitimate method of heating water when properly implemented, but since the body of water itself becomes electrically live, safety considerations are paramount. When designed properly, there is no possibility of user contact with the electrodes. Unfortunately, there are versions of these devices avail- Fig.11: a questionable water heater being tested by YouTuber EEVblog (David L Jones). 18 Silicon Chip Mains travel adapters Travellers frequently need an adaptor so they can plug a mains powered device from their home country into another country’s power outlet. These devices generally only provide a mechanical interface from one type of plug to another, but do not convert the voltage. So you need to be sure that your device will work with the mains voltages in the countries you travel to. Many devices will operate from 100-240VAC at 50Hz or 60Hz, which covers virtually all countries. There are many Fig.12: a test by DiodeGoneWild of an electrode boiler water heater, with smoke and flames liberated. Australia’s electronics magazine siliconchip.com.au Fig.13: an unsafe power adapter, as shown on the web page of WA’s Department of Mines, Industry Regulation and Safety. Two consumers received electric shocks using this device. of these devices available, and ones purchased online from overseas have a high likelihood of being dangerous. In August 2017, WA’s Department of Mines, Industry Regulation and Safety issued a warning about an unsafe power adapter intended to allow the mains plug of an appliance of one country to be used in another (Fig.13). The government department only cited one fault with the device, but there were many more. The warning is at: siliconchip.com.au/link/aatu and you can see a video describing the dangers, titled “Dangerous power adaptors” at: siliconchip.com.au/link/aauk YouTuber DiodeGoneWild reviewed the same device in a February 2017 video titled “Universal Travel Shock-dapter (Dangerous Adapter)”, at: siliconchip.com.au/link/aaul This device converts between US, Australian, UK and various European plugs but with no voltage conversion. There is no Earth connection, but it can power appliances that require an Earth. It is also possible to insert some plugs with only one pin inside the adapter and one pin outside, leaving a live pin outside the unit (see Fig.14). Worse still, it is possible to plug the adapter into a European socket and then disengage the UK, US or Australian Fig.14: YouTuber DiodeGoneWild demonstrating a universal power adapter plugged into a European socket, with the live UK pins disengaged and powering a light bulb. pins from the unit which are then live. A child-protection safety shutter over the holes is not functional, and there is no surge protection despite a label that says there is. Apart from travellers, many devices sent to Australia from overseas sellers don’t have an Australian power plug and instead, come with a free adaptor. These are frequently dangerous – see Figs.15 & 16. The applicable Australian/New Zealand Standard for these devices is AS/NZS 3122:2015. Make sure any device you purchase is compliant. Safety compliance labels are shown in Figs.17 & 18. You can spot many non-conforming units straight away because the plug pins are typically not insulated near their base, as is required by the latest standard. Editor’s note: I had one of these at home which came with something I bought, but I decided not to use it as I Fig.16: another US and EU to Australian (or Chinese) adapter. This one also lacks the insulated pin bases and can accept an appliance with an Earth pin which would go beyond the edge of the device and would not make a connection. This one was from eBay, delivered from overseas for A$1.00 plus GST. These are frequently provided for free with mains equipment sent to Australia from overseas sellers. Fig.17: an Australian safety compliance label, showing the approval number. Fig.15: an example of an electrical adapter found on eBay to enable appliances with US, UK or various European plugs to be used in Australia (or China). It accepts the plug of an Earthed appliance but does not itself have an Earth pin. The bases of the pins are also not insulated, as required by the Australian Standard. This one cost A$1.33+GST from overseas. It is also possible to plug just one pin of a device into the socket, rendering the other pin live. siliconchip.com.au Australia’s electronics magazine Fig.18: a regulatory Compliance Mark which may be affixed to a compliant travel adapter. It indicates compliance with applicable Australian requirements. December 2019  19 Figs.20 & 21: by way of contrast, this shows how a three-phase plug and socket should be made to Australian standards; a Clipsal 56P532 plug and 56C532 socket, both rated at 32A, 500V. Fig.19: a Chinese 32A 440V plug and socket that is not compliant with Australian standards. In Australia, threephase power used to be 415V RMS but is now 400V RMS to harmonise with European standards. The 440V rating is the claimed voltage rating of the plug and socket. could see it didn’t meet local electrical rules. But without my knowledge, my wife found it and used it to power an induction cooker. When she complained that the cooker wasn’t working properly, I noticed the adaptor and found it was very hot! I replaced it with a proper travel adaptor and the cooker then worked fine. Don’t leave these poor quality adaptors lying around; just get rid of them. You never know who might try to use them when you aren’t looking! Substandard three-phase plugs and sockets In a video titled “Horror Chinese 32A 440V Power Outlet and Plug Autopsy” at: siliconchip.com.au/link/aaun YouTuber Aussie50 looked at a three-phase mains power plug supplied with factory equipment imported from China. The 11kW machine, as supplied, had no Earth wire (see Fig.19). The following problems were found with the supplied plug: • insufficient clearance between power pins and screws used to hold the unit together • wiring was too small a gauge • clamp to secure original cable ineffective, as the case is made of a material that was too hard to compress, so the cable could move freely in and out of the plug • power pins of plug free to rotate and come loose • no isolation barriers between wires • the nuts that hold the wires on can come loose • wires were tinned before being screwed in (not a good idea) • the washers used with the nut to hold the wires on were made of recycled material with poor conduction • the Earth pin does not enter the socket before other live pins, so phases can connect before Earth • questionable insulation of supplied wires, probably rubber-based with no or little fire retardant • pins too thin to fit properly into an Australian threephase outlet Safety problems with a matching socket purchased separately included: • no sideways wire entry • cheap plastic tooling and moulding • Earth socket made of cheap, fragile metal which is easily broken 20 Silicon Chip • Earth pin on top as per Chinese standard rather than the bottom as with Australian standard • terminals not isolated from each other • nothing to prevent foreign matter falling into pin hole • nothing to prevent long wires from shorting against a metal backing panel Powerboards From time to time, we get letters from SILICON CHIP readers complaining about the poor quality of electrical power boards they have purchased. It is not clear if these boards are genuine ones made to Australian standards or counterfeits. Powerboard safety is a serious and prevalent issue. In the five months prior to 22nd December 2014, the Australian Competition and Consumer Commission received 13 recall notifications for these devices and urged consumers to inspect all their power boards and double adapters. See the list of recalled products at: siliconchip.com.au/link/aatv These recalls arose because the original samples of supplied products received approval for sale in Australia, but there were post-approval changes in the design or manufacturing process which rendered them no longer safe. Powerboards are required to be fitted with an overload protection device to avoid overheating and becoming a fire risk. The applicable Australian and New Zealand Standard for domestic power boards is AS/NZS 3105:2014, “Approval and test specification - Electrical portable outlet devices”. Mains power plugs and sockets from Australian manufacturers can be considered safe, but consumers should be aware of the possibility of fake items that might find their way onto the market. Also, non-compliant plugs and sockets should never be connected to Australian mains power. Copper or steel wire? Some products from China use steel rather than copper for conductors in electrical wire. The steel is much cheaper than copper and may be plated with copper to give it the appearance of being solid copper. A simple test to establish the composition of suspect conductors is with a magnet (see Fig.22). Steel is a substantially worse electrical conductor than copper and less malleable, so these wires will make bad and possibly dangerous high-resistance crimp-style connections. Dangerous battery chargers Just as you should only buy rechargeable batteries from a reputable source (there are millions of fakes out there!) it’s essential to buy a good quality battery charger, especially for lithium-ion cells. An inappropriate charger can cause the battery to catch fire. In a video titled “Li-Ion cell charger with (too) simple Australia’s electronics magazine siliconchip.com.au Fig.22: ever seen magnets stick to copper? They will if the “copper” wire is actually made of much cheaper steel with copper coating! This was determined with a magnet by Blogger “nophead”; see: siliconchip.com.au/link/aatw design. With schematic. Charges to 4.45V!” at: siliconchip. com.au/link/aauo YouTuber “DiodeGoneWild” describes a lithium-ion battery charger of Chinese origin, purchased on eBay for US$1.19 including shipping to Europe. It had no fuse, no inrush current limiting resistor, no interference filter, questionable separation between low voltage and mains PCB tracks (1mm) and the output voltage was too high due to the use of a zener diode as a shunt regulator (see Fig.23). The device charged the battery to 4.45V per cell. Most lithium-ion batteries should not be charged beyond 4.2V (follow manufacturer’s instructions). Beyond 4.3V, metallic lithium will be plated onto the anode, and the cathode starts to produce CO2 gas. For cells with a sealed metal container, such as the 18650 types commonly used in laptops or Tesla cars, once the cell pressure reaches 1000-1380kPa (145-200psi), the current interrupt safety device (if fitted!) should stop the flow of Look out for dodgy mains cords This one is not directly applicable to antipodeans, as it involves a UK-style mains cord. But you could possibly buy equipment on the internet and get a cable with a similar problem. YouTuber Jim Conner’s video, titled “Illegal and Deadly imported UK Plug Rant” can be seen at: siliconchip.com.au/link/aaum UK power plugs are unusual in that they always incorporate a fuse. This design has its origins in the second world war, due to a shortage of copper. To save copper wiring, power outlets were put on a 32A “ring main” with 10A rated outlets. In other words, the power outlets are chained, rather than being individually wired back to a distribution panel. Therefore, each 10A outlet needed a 10A fuse; omitting it would be like omitting a fuse or circuit breaker at the distribution panel in an Australian system. In this particular example, the UK plug supplied had no fuse, and the wire in the cable could not handle the 10A claimed. In the video, the cable melted while passing just 5.5A! Even if it had been a compliant plug with a 10A fuse, the cable could have started a fire. So watch out for suspiciously thin mains cords. But even that may not be a giveaway, as thin wire could be ‘bulked up’ with siliconchip.com.au Fig.23: the circuit of the lithium-ion battery charger that charged to a dangerously high voltage. The poor voltage regulation is due to the zener diode at lower right. The voltage across a zener diode is dependent on the current going through it and therefore will vary as the load changes due to the battery charging. It is therefore unsuitable for this application. current. But if the pressure rises further, the safety membrane on some lithium batteries bursts at about 3450kPa (500psi) and flame may be “vented” (see photo on p14). This is another reason to always use good quality protected cells (those with a protection circuit board) if using lithium-ion batteries in your project. Note that lithium-ion cells, especially those with a metal can such as 18650s, are safe if used and charged correctly. Electrically heated “suicide” showerheads Direct electrically heated shower heads would not be legal in Australia or most other Western countries, but are nevertheless available online for Australians to purchase. In one word: DON’T! They are extremely popular in Central and South America, and also available in Africa and Asia, where central hot water systems are less common or non-existent, as are strict electrical standards (see Figs.24-27). thicker insulation. In general, it’s best to avoid foreign-supplied mains cables entirely. You never know whether they will meet their claimed specifications. Australia’s electronics magazine December 2019  21 Fig.24: a screengrab from DiodeGoneWild’s teardown video of a ‘suicide’ showerhead, showing the heating elements in the water stream. What little safety these devices have relies on water resistivity being below a certain threshold, which may not be the case where water mineral content is high. They also rely on a functional Earth connection for safety, but many installations don’t have one or don’t connect it. Australian tourists may encounter these when overseas, so be very careful. Not surprisingly, people have died from using these units. See the video series by YouTuber DiodeGoneWild starting with the one titled “Electric heated ‘suicide’ shower PART 1 - teardown & calculations” at: siliconchip.com.au /link/aauq In this video, a popular ‘suicide’ shower head was examined, and electrical measurements were made of an installed unit. The findings were as follows: Water is heated ‘on the fly’. There is a high and low power switch with a stated 5400W power consumption on high. Wires are spot welded to the device, meaning there is no way to fit longer wires. The very short supplied wires have to run to a terminal block or similar device, mounted close to the showerhead, which may be exposed to water. The heating element is bare and exposed to water rather than enclosed in a sheath; there is a possibility that with insufficient water flow, the device could overheat and burn. The metal switch contacts are bare copper and not plated with tin or nickel to reduce corrosion. The investigator could only get the device to operate by Fig.25: a typical installation (one of the better ones!) of a ‘suicide’ showerhead in Brazil. The Earth wire is not connected. Image source: Tweet by AbwesenTweets. 22 Silicon Chip Fig.26: in bigclivedotcom’s teardown of the suicide shower head, he discovers that the bare end of the “Earth wire” in the outlet water stream is covered with silicone, so it is not effective. The purpose of this oddly placed wire is to conduct any residual current to Earth before it reaches the user; at least, if there is a functional Earth connection. connecting the device to a circuit without an RCD; 190mA current flowed through the Earth on the high setting and 130mA on the low setting. Surprisingly, there was no shock to the tester with one hand directly under the showerhead and the other hand on an Earthed plate, but this was with a proper Earth installed to the unit. With no Earth connected, about half of the mains voltage was present directly at the outlet of the water and 25mA of current would flow to Earth. The tester received an unpleasant sensation with his finger directly under the water outlet, with a few milliamps flowing through his body. The current flow dropped off rapidly as he moved his fingers away from the outlet. The showerhead would work with an RCD-protected circuit if the Earth wire was not connected, but in this case, the RCD would not trip despite the current flowing through his body. Given all of the above, the investigator concluded that if the device was correctly Earthed (that’s a BIG if in the sort of places these devices are installed), it is almost impossible to get a shock, assuming there are no faults. However, with no Earth connected, it is definitely possible to get a shock from it. Fig.27: a ‘suicide’ shower-head in Latin America with no top cover and the Earth wire not connected, just hanging in midair. Image source: http://johnnyvagabond.com/travel-tips/ survive-suicide-shower/ Australia’s electronics magazine siliconchip.com.au We recommend avoiding this type of shower head on your travels. You never know how well they have been installed or maintained. YouTuber bigclivedotcom also reviewed one of these units in a video titled “Inside a heated shower head (suicide shower)” at: siliconchip.com.au/link/aaur (see Fig.26). He made additional observations that Western tourists to the countries that use these devices tend to be taller than the locals that use them, and therefore their heads are closer to the units. So they are more likely to experience electrical sensations (or worse). Also see Australian YouTuber David L Jones’ look at the product, in a video titled “EEVblog #873 - World’s Most Dangerous Consumer Product!” at: siliconchip.com.au/ link/aaui Finally, in a video titled “Teardown of a UK electrically heated shower unit” at siliconchip.com.au/link/aaus bigclivedotcom looks at an electrically-heated shower unit made to UK standards. The water is heated in a separate space, rather than in the head, and it has extensive safety features and is built to a high quality. We’ve seen 10A extension leads where the plastic has simply melted, leaving all pins exposed. While you can’t easily check the socket, if the pins on your extension lead are tarnished or corroded, we’d be taking to them with a wire brush or emery cloth to bring them back up to bright, shiny condition. If you cannot do that, it’s best to replace the plugs and sockets with new ones. But take care with the wiring – follow the instructions on the packs! And finally! We couldn’t resist showing this photo we found on the ’net. No, it wasn’t set up just for the photo! A more dangerous jerry-rig is hard to imagine, even more dangerous than using one of the dodgy adaptors we’ve talked about in this feature. One flash and you’re ash, and all that . . . SC Extension lead problems All extension leads sold in Australia must be approved and labelled (at least at time of purchase) with their current rating. “Everyone knows” (!) you shouldn’t use a damaged lead – if it’s nicked it should be discarded. Most leads are rated for 7.5A or 10A; some (usually sold as “caravan leads”) are rated at 15A and have a thicker Earth pin to prevent them being used on a standard (10A) GPO. But have you noticed your extension leads, or more correctly the plug and socket, are very hot after use with a high power device? Take a look at the pins on the plug; are they tarnished or weathered? That creates a higher-than-normal resistive connection, and high resistance usually equals heat – lots of it! SILICON CHIP * Every effort is made to keep all boards in stock. In the event that stocks run out, there is normally only a two week delay in restocking. Applies to all boards since 2010, excepting those where copyright has been retained by the author. S ILICON C HIP LCR Wallchart You’ll wonder how you got by without one! INTERNET Credit/Debit Card* etc siliconchip.com.au Fig.28: Temporary Australians! Nail clippers used to adapt a US plug to an Australian power outlet! ONLINESHOP . . . it’s the shop that never closes! 24 hours a day, 7 days a week . . . it’s the shop that has all recent SILICON CHIP PCBs – in stock* . . . it’s the shop that has those hard-to-get bits for SILICON CHIP projects . . . it’s the shop that produces those professional laser-cut acrylic cases . . . it’s the shop that has all titles in the S ILICON C HIP library available! . . . it’s the shop which maintains back issues for sale (until they run out!) . . . it’s the shop where you can get a project reprint if back issues unavailable . . . it’s the shop where you can place an order for a subscription (printed or on-line – or both!) from anywhere in the world! . . . it’s the shop where you can pay on line, by email, by mail or by phone Australia’s own mighty MicroMite PLUS: Explore 100, Explore 64 and projects PAYPAL (24/7) Use your PayPal account silicon<at>siliconchip.com.au And all those hard-to-get project components: Currawong Valve Amplifier SidRadio Parts eMAIL (24/7) with order & credit card* details silicon<at>siliconchip.com.au *Mastercard or Visa only The complete Radio, TV & Hobbies on one DVD! GPS Units (as used in many projects) MAIL (24/7) your order to PO Box 139 Collaroy, NSW 2097 PHONE (9-5, Mon-Fri) Call (02) 9939 3295 with order & credit card* details Browse online now at www.siliconchip.com.au/shop siliconchip.com.au Australia’s electronics magazine December 2019  23 Most cheap battery chargers – the type you might buy at a hardware store or auto retailer – are pretty dumb. As many people have discovered (because they are so dumb) they can actually destroy the battery under charge! If you have one of these chargers, you can upgrade it to one with a clever controller, suitable for flooded lead-acid, sealed lead acid (SLA) or even LiFePO4 rechargeable batteries. CLEVER CONTROLLER for a DUMB DU MB BATTERY CHARGER BY JOHN CLARKE M any manufacturers’ idea of a battery charger is a transformer, a diode or two and a pair of clip leads . . . and not much else! You may even have one of these sitting on a shelf in the garage. They’re everywhere! Sure, it will charge a flat battery but the chances are if you don’t unclip it, it will keep on charging and charging and charging . . . until the battery electrolyte is boiled dry, the plates are buckled or, worst case, you have a fire on your hands that may be very difficult to control! Our new Charge Controller is used in conjunction with one of these basic, low-cost lead-acid battery chargers. It transforms this ‘dumb’ charger into a more advanced device that can still charge at the same maximum rate, but also offers A 12V 2 3 0V AC 0V 12V N 12V TRANSFORMER A + K DIODE 1 A  DIODE 2  Silicon Chip 12V RMS A K GREEN LED K TO BATTERY 12V ZENER A 24 17V PEAK 330Ω K THERMAL CUTOUT proper charge termination, float charging and temperature compensation. Since it’s fully adjustable, it caters for the Lithium-Iron-Phosphate (LiFePO4) batteries that are starting to become available as a replacement for lead-acid types. Compared to lead-acid, LiFePO4 offer faster charging and discharging, more charge cycles, smaller volume and lighter weight, albeit at a higher cost. Adding a fully automatic Charge Controller to a basic charger will also prolong the life of your batteries, and you can leave a battery on a float charge as long as you want, ready for use when required. LiFePO4 batteries usually are not float charged, so you can disable that step for these batteries. – 0V Fig.1: the basic arrangement of a typical low-cost lead-acid battery charger. It consists of a centre-tapped mains transformer and a full-wave rectifier (D1 & D2). There’s usually a thermal cutout and perhaps a LED indicator to show when the battery is charged. The output voltage of this simple arrangement is shown above. Australia’s electronics magazine siliconchip.com.au VOLTS UNLOADED CHARGER OUTPUT Features BATTERY VOLTAGE 0 10ms 20ms 30ms TIME • Charges 6V, 12V or 24V flooded lead-acid, SLA or LiFePO4 batteries at up to 10A (with a suitable charger) • Charge rate: adjustable from 1-100% of charger capability in 1% steps • One, two or three charging phases: bulk, absorption and float • Adjustable or pre-set charge termination and float voltages CURRENT • Adjustable temperature compensation for lead-acid batteries with an internal or external thermistor TIME A CHARGING VOLTAGE AND CURRENT BATTERY VOLTAGE • Automatic slow charge mode for heavily discharged batteries • Battery discharge protection UNLOADED CHARGER OUTPUT REQUIRED BATTERY VOLTAGE • Cold battery charge protection (won’t charge below 1°C) • Thermistor fault protection (won’t charge lead-acid batteries if the thermistor is open or short circuit) • Six status indicator LEDs with error indication • Low-cost, easy to build and easy to use • Microprocessor controlled CHARGING TIME B CHARGING CHARACTERISTIC Fig.2. in more detail, the charging current from the circuit shown in Fig.1 consists of a series of high-current pulses at 100Hz. As shown in part (b), the relatively high peak voltage can result in the battery being over-charged if the charger is left on long enough. Basic charger flaws The configuration of a typical low cost lead-acid battery charger is shown in Fig.1. It comprises a mains transformer with a centre-tapped secondary output. The output is rectified using two power diodes to provide raw DC for charging the battery. A thermal cutout opens if the transformer is delivering too much current. Charge indication – if it is present at all – may be as simple as a zener diode, LED and resistor. The LED lights when the battery voltage exceeds the breakdown voltage of the zener diode (12V) and the forward voltage of the green LED (at around 1.8V). Thus the LED begins to glow at 13.8V and increases in brightness as the voltage rises. Some chargers may also have an ammeter to show the charging current. The charging current to the battery is a series of highcurrent pulses at 100Hz, as shown in Fig.2(a). The nominal 17V peak output from the charger will eventually charge a battery to over 16V if left connected long enough, which will damage the battery. As shown in Fig.2(b), the maximum battery voltage for a full charge (called the cut-off voltage) is exceeded when left on charge for too long. The solution By adding in the Charge Controller to that simple charger, we can do much better. siliconchip.com.au Fig.3 shows how the Charge Controller is connected in between the charger and the battery. The Charge Controller is housed in a compact diecast aluminium case. In effect, the Charge Controller is a switching device that can connect and disconnect the charger to the battery. This allows it to take control over charging and to cease charging when the correct voltage is reached. The various charging phases for lead-acid batteries are shown in Fig.4. The Charge Controller can switch the current on or off and apply it in a series of bursts ranging from 20ms every two seconds through to a continuous current. During the first phase, called bulk charge, current is typically applied continuously, to charge as fast as possible. After the bulk charge phase, the Charge Controller switches to the absorption phase. This maintains the cutoff voltage for an hour by adjusting the burst width while it brings the battery up to an almost full charge. After that, the Charge Controller switches to float charge. This uses a lower cut-off voltage and a low charge rate, to keep the battery fully charged. The switch from absorption to float occurs when the + + + – – – LEAD-ACID BATTERY CHARGER + – CHARGE CONTROLLER BATTERY Fig.3. the Charge Controller is connected between the charger and battery. It takes control over charging and ceases charging the battery at the correct voltage; ie, when it is fully charged but before it becomes over-charged and starts out-gassing (or worse). Australia’s electronics magazine December 2019  25 Specifications • • • • • • • • • • • • • • • • Charging pulse width: 20ms-1980ms in 20ms steps, or continuous Charging cut-off voltage: 0-30.5V in 29.8mV steps. Independent LiFePO4, SLA and lead-acid battery settings (presets are also available, see Table 1) Temperature compensation: 0-50mV/°C in 256 steps (separate SLA and lead-acid battery adjustments) Minimum battery charging temperature: 1°C Maximum compensation temperature: 60°C Under-voltage burst charge: 5.25V for a 6V battery, 10.5V for a 12V battery, 21V for a 24V battery Under-voltage burst rate: 200ms burst every 2s at maximum charge rate. The burst width is reduced with a lower charge rate (10% of the normal rate). Battery discharge protection: if charger power is lost, it switches off after two hours with battery voltage below 6.25V (for a 6V battery), 12.5V (for a 12V battery) or 25V (for a 24V battery) Power on: LED1 lights Thermistor error: LED2 lights Temperature too low: LED2 flashes at 1Hz Bulk charging: LED3 lights Absorption charging: LED4 lights; optionally, LED3 flashes to indicate charge rate Float charging: LED5 lights; optionally, LED3 flashes to indicate charge rate Battery detected: LED6 lights Battery voltage low, charging slowly: LED3 flashes; if charging a lead-acid battery, LED4 and LED5 also flash charging current drops to 3% of the original bulk charge rate or after an hour, whichever comes first. The absorption phase is optional; you can opt to skip this phase and go straight from bulk charging to float charging. When absorption is enabled, this phase will be bypassed if the bulk charge takes less than an hour. This prevents excessive absorption phase charging with an already fully-charged battery. While the bulk phase is usually done at the full rate, for lower capacity batteries where this charging current would be too high, the burst width can be reduced to limit the average current. For example, if you have a 4A battery charger, the current can be reduced from 4A anywhere down to 40mA in 1% steps, using the charge rate control. CUTOFF VOLTAGE CUTOFF POINT BATTERY VOLTAGE FLOAT VOLTAGE BULK CHARGE ABSORPTION Lithium-Iron-Phosphate battery charging Typically, LiFePO4 batteries are charged to 3.47V per cell, although 3.6V per cell is also used. A nominally 12V LiFePO4 battery therefore has four cells, and the cut-off voltage is either 13.88V or 14.4V, depending on which percell figure you use. The charge controller can cease charging once the cut-off voltage is reached, or you can opt for an absorption phase. During this phase, the cut-off voltage is maintained for an hour, or until charging pulses drop to 3% of the original bulk charge setting. Lead-acid cut-off & float voltages The actual cut-off and float voltages for lead-acid batteries are dependent on the particular battery, its construction and the operating temperature. Typical cut-off and float voltages at 20°C are 14.4V and 13.8V, respectively. For sealed lead acid (SLA) batteries, the voltages are lower at 14.1V and 13.5V respectively. Setting SLA Flooded LiFePO4 lead-acid Cut-off voltage 14.1V 14.4V 13.88V Float voltage 13.5V 13.8V None Temperature compensation -25mV/°C -20mV/°C None FLOAT CHARGE CURRENT Table 1 – default settings TIME Fig.4: the three typical charging phases for a lead-acid battery. It starts with the bulk charge phase, then switches to the absorption phase (optional, selected using JP2) for an hour or so, and then finally switches to float charging to finish charging and keep the battery charged. For LiFePO4 batteries, there is no float phase. The charger switches off when the battery is fully charged and switches back on again later if it becomes discharged. 26 Silicon Chip Setting Set by SLA & LiFePO4 VR2 VR3 0-30.5V* 0-30.5V* 0-30.5V* None VR4 0 to -50mV/°C None Flooded lead-acid Cut-off voltage Float voltage Temperature compensation Table 2 – adjustable settings    *in 29.8mV steps Australia’s electronics magazine siliconchip.com.au TO CHARGER Q1 IRF1405N F1 10A 100  1W – K D1 1N4004 A A G TP5V REG1 LM317T K K ZD1 18V 220 F ADJ A 50V ZD2 18V 8 120 1k 16V A 3 POWER D2 1N4004 RLY1 (5V) 2k 15 Q3 BC337 VR1 10k 3.3k 18 RA3 /AN3 AN1/RA1 RA4 17 AN0/RA0 10nF VR3 10k +5V 13 12 4 16 AN5/RB6 RA2/AN2 RB4 A RLY1b RB5 1k 8 1k 1k 1k 1k A A A LED2  LED3  LED4  K 100nF BATTERY  LED6 K K K LED2: THERMISTOR LED3: CHARGE LED4: ABSORPTION LED5: FLOAT  K C Q2 BC337 B E 10k 1 11 STORE RA7/OSC1 EXTERNAL THERMISTOR T S2 R THERMISTOR 100nF TH1 5 S CON1 BC 33 7 LEDS K A 10k A 10k LED5 A Vss ZD1, ZD2 K 7 RA5/MCLR 10nF K 6 RB1 AN6/RB7 10nF 1k 1: SLA 1 2: FLOODED LEAD-ACID 2 OPEN: LITHIUM 3 RB2 10 JP3 A 100nF 51k RB0 TP4 VR4 10k 1N4004 100k 2 10nF +5V 2 2: ABSORPTION 4 9 IC1 PIC1 6F8 8 PIC16F88 TP3 1: STANDARD 1 20 1 9 RB3 TP2 VR2 10k JP2 SC  Vdd RA6/OSC2 10nF E JP1 2 TTC 100nF B OUT: DEFAULT 12V IN: ADJUST. INPUT 100nF K 14 TP1 C 6 +5V A 56 SOURCE Mcap2 GND +5V K 5 GATE +5V IC2 7 Mcap1 Si87 51  LED1 VR5 100 A 1 +5V 100 F 330 K – 10pF +5V OUT IN S1 POWER + D3 1N4004 RLY1a  + TO BATTERY S D B E IRF1405N IC2 8 C UNIVERSAL BATTERY CHARGE CONTROLLER 4 1 G LM317T D D S OUT ADJ OUT IN Fig.5: the Charge Controller circuit is based around a PIC16F88 microcontroller (IC1). This monitors the battery voltage at its AN3 input and switches Mosfet Q1 on and off via isolated driver IC2, to control the charging. These values, plus 13.88V for the LiFePO4 battery, are pre-set within the Charge Controller and selected using the Lead-Acid/SLA/Lithium jumper shunts, but only when the “default” shunt is inserted (not “adjustable”). See Table 1. Other settings are possible, and can be set manually from 0-30.5V in 29.8mV steps – see Table 2. These voltage settings can also be compensated for temperature changes; as the temperature rises, the charge voltages for a lead-acid battery are normally reduced. A typical temperature compensate is -20mV/°C for flooded cells and -25mV/°C for SLA batteries. LiFePO4 batteries do not require temperature compensation. Temperature compensation values can be set from besiliconchip.com.au tween 0 to -50mV/°C in 256 steps. Temperature compensation is applied for temperatures between 0°C and 60°C. No charging is allowed at temperatures at or below 0°C, to protect the battery. A negative temperature coefficient (NTC) thermistor is used for temperature measurement, and the charge controller will use the internal thermistor if an external one is not connected via its jack socket. The external thermistor provides for a more accurate measurement when it is placed against the battery. Four trimpots are used to make the settings. One sets the charge rate, as a percentage of the full charge current available from the charger. The remaining three are for setting Australia’s electronics magazine December 2019  27 Transmitter Receiver MODULATOR A SemiconductorBased Isolation Barrier Input Signal DEMODULATOR Modulation Signal B RF OSCILLATOR Output Signal Fig 6(b): Modulation Scheme Fig. 6(a): Simplified Channel Diagram Fig.6: an excerpt from the Si8751 data sheet, showing its internal arrangement. It comprises an RF transmitter and RF receiver to transmit gate drive power and control from the input side to the output. The receiver is isolated from the transmitter by a semiconductor isolation barrier, rated at 2.5kV. When the RF transmitter is producing RF signal, a gate drive voltage appears at the output. When there is no RF transmission, there is no gate drive voltage. the cut-off voltage, float voltage and temperature compensation adjustments. When charging the battery, the microcontroller adjusts the pulse duty cycle to reach the desired battery terminal voltage using negative feedback. The duty cycle is reduced by 15% every two seconds if the battery voltage is above the required value by more than 0.25V, or reduced by 1% every two seconds if the battery voltage is above the required value by less than 0.25V. Conversely, the charge duty cycle is increased at a fast rate (3% per two seconds) if the battery voltage is more than 0.25V below the required value and increased at a slow rate (1% per two seconds) if the battery voltage low by less than 0.25V. LED indicators The Charge Controller has six LED indicators. LED1 (green) shows power is applied, while LED2 (orange) flashes when the thermistor temperature is below 0°C but otherwise does not light unless the thermistor connection is broken or shorted. LED3 (red) indicates the bulk charge phase, while LED4 (orange) and LED5 (green) indicate the absorption and float phases. Scope1: scope grab of the Charge Controller with a 2A charger and a lead-acid car battery. The yellow trace shows the charger output, the green trace the battery voltage and the blue trace the charge current. Note how the battery voltage varies with the charging current. The difference in voltage between the charger and the battery is due to the current shunt and cable losses. 28 Silicon Chip LED6 (green) indicates that a battery is connected, but is not an indication that charging is occurring. There is an option for LED3 to indicate when current is being fed to the battery during the absorption and float phases. This is useful, as it flashes whenever current is being fed to the battery. So it indicates the duty cycle of power bursts. Brief bursts indicate that the battery is close to the required voltage while longer bursts indicate that the battery requires further charging. If this is not required, it can be disabled so that LED3 only lights during the bulk phase. The absorption LED (LED4) will never light if you set up the charger to skip this phase. Similarly, the float LED (LED5) does not light when charging LiFePO4 batteries, since that phase is not used for Lithium batteries. Isolated Mosfet drive The circuit of the Charge Controller is shown in Fig.5. It uses a PIC16F88-I/P microcontroller (IC1) to monitor the battery voltage and adjust the switching of an N-channel Mosfet (Q1) to control the charging rate. Q1’s channel is connected between the incoming positive supply (drain) and the battery positive terminal (source). Scope2: the same charging scenario as Scope1 but at a much longer timebase, showing the many pulses that make up two seconds of charging. Australia’s electronics magazine siliconchip.com.au To switch Q1 on, its gate needs to be brought several volts higher than its source. Since the source is at the battery voltage, we need a way to generate a voltage above this. This needs to be controlled by a 0-5V control signal from microcontroller IC1. To accomplish this, we use an Si8751 isolated FET driver (IC2). It provides up to 2.5kV of isolation between its input and output but here, 45V is sufficient. IC2 runs from the same 5V supply as microcontroller IC1, and Q1’s gate is driven from pin 8. The Mosfet source is connected to pin 5. The gate drive output at pin 8 typically charges the gate to 10.8V with respect to the source when the input at pin 3 is high (5V). The gate output is pulled down to the source voltage with a 0V input. The 10pF capacitor between drain and MCAP1 (pin 7) enables a feature of the chip to prevent a fast voltage rise at the Mosfet drain from coupling into its gate and spuriously switching it on. Internally, IC2 comprises an RF transmitter and RF receiver to send gate drive power from the input side to the isolated output. Isolation is provided by a semiconductor oxide barrier. When the transmitter is producing an RF signal, this is detected in the receiver to produce the gate drive voltage. When there is no RF transmission, there is no gate drive. See Fig.6 for details of its internal operation. The gate drive current is set by the resistor at pin 2. In combination with the Mosfet gate capacitance, this determines the Mosfet switch-on time. With the 100kΩ resistor we’ve used, the switch-on time is around 5ms to a gate voltage of 5V. It continues to rise to about 10V, but the Mosfet is already mostly in conduction by 5V. The 100kΩ resistance we have chosen reduces the supply current for IC2 from 13.8mA down to 1.8mA, compared to the fastest option of connecting pin 2 directly to ground, which would give a 1ms switch-on time. The 100nF capacitor across the 100kΩ resistor speeds up switch-on without increasing current consumption. The switch-off time is typically 15µs, regardless of the resistor value at pin 2. Fast switching is not required in this application, as Scope3: we have now reduced the charging duty cycle to around 75% and the average current delivered to the battery has dropped (the reading is unrealistically low due to the timing of the pulses). Note how the battery voltage rises during the bursts, then falls a little between them, averaging lower than before. The charger output voltage rises substantially when it is not delivering current. siliconchip.com.au Using the Charge Controller with 6V batteries The circuit as presented is suitable for use with 12V or 24V batteries and chargers, but it can easily be modified for 6V batteries and chargers with a few changes. Note that if you make these changes, you can only use the unit with a 6V charger. The changes required are: replace D1 with a 1N5819 Schottky diode, change the 100Ω 1W resistor to 10Ω 1W and change REG1 to the low-dropout version, LD1117V. ZD1 should be changed to a 15V 1W type and ZD2 replaced with a wire link. The default position for JP1 cannot be used with 6V batteries; set the adjustable cut-off voltage, float voltage and temperature compensation values to suit your 6V particular battery. we’re only switching the Mosfet on and off once every two seconds. Low current consumption is important so that REG1’s dissipation is below 1W when charging a 24V battery. Otherwise, the regulator will run very hot and need heatsinking beyond that provided by the PCB. Switching losses increase when the switching is slow because the Mosfet’s dissipation is at a maximum when it is in partial conduction. The instantaneous losses can be high (hundreds of watts at many amps), but as they are infrequent, the average is low. Switching losses are: (switchon loss + switch-off loss) x switching frequency. So losses are directly proportional to frequency. Fig.7 is an oscilloscope screen grab showing the gate drive waveform for Mosfet Q1. The period for the gate to rise from 0V, with the Mosfet off, to fully conducting (4.5V) is 5ms. The switch-off time is relatively fast at around 35µs for the full gate voltage excursion. The overall energy loss in the Mosfet (and therefore heating) is the switching losses plus the static losses. We’ve already described that the switching losses are reasonably low. The static losses are simply the average current times the Mosfet’s on-resistance. Its on-resistance is low enough Scope4: now the duty cycle has been reduced to 50% and the battery voltage and average charge current have dropped a little further. Australia’s electronics magazine December 2019  29 Making a fully self-contained charger While the emphasis in this project has been to make a dumb battery charger clever, we can already hear the question: What do you do if you don’t have a dumb battery charger? The answer to that is simple! There is absolutely nothing to stop you making one, as per Fig.1 in this article, and add it to the project! You won’t need the LED/zener indicator (the Charge Controller tells you everything you need); the thermal cutout wouldn’t do any harm, though! In fact, you could place a 12V CT transformer and a pair of diodes in a larger case and include this project to have a fully self contained, clever battery charger. If you can’t lay your hands on a 12V CT transformer, a single-ended 12V with a bridge rectifier will do the same job. Just remember that the transformer (in either case) must be a standard iron-core type (not an electronic type) rated high enough – we’d suggest 4A or 50W (did we hear someone say an old 12V downlight transformer?). And the diodes or bridge need to be pretty beefy, too – a pair of automotive diodes or a 30A bridge, for example. Make sure the mains wiring side is exemplary – in fact, all wiring must be workmanlike, properly anchored and so on. Any metal case should be properly Earthed (via the power cord). So away you go . . . that even at 10A, the static losses are within reason. Circuit description Power for the circuit is usually obtained from the ‘dumb’ charger via reverse-polarity protection diode D1, although it can also flow from the battery via the body diode within Q1. However, the latter has no useful function and can eventually discharge the battery. We have a solution for that, which is described below. The incoming supply also passes through a 100Ω dropper resistor and either power switch (pushbutton) S1 or the contacts of RLY1, and is then filtered by a 220µF electrolytic capacitor and fed to an LM317T ad- Scope5: the duty cycle has now been reduced to 10% but the battery is still charging (slowly), with an average terminal voltage of 13.2V. 30 Silicon Chip justable regulator (REG1), set to deliver a precise 5.0V. For REG1, the voltage between the OUT and ADJ terminals is a fixed reference value of typically 1.25V, but it could be between 1.2 and 1.3V. Assuming it is 1.2V, the 120Ω resistor between these pins has 10mA (1.2V ÷ 120Ω) flowing through it, which also passes through the 330Ω resistor and trimpot VR5. We need 3.8V at the ADJ terminal for a 5V output (3.8V + 1.2V), so the total resistance of VR5 and the 330Ω resistor needs to be 380Ω for the 10mA current to produce this voltage. VR5 is therefore adjusted to give 50Ω. This adjustment is provided to allow for variations in REG1’s reference voltage and the resistor values. The 5V supply feeds both IC1 and IC2. The accuracy of the 5V setting adjustment determines the precision of the battery charge voltage settings. That is because IC1 uses the 5V supply as a voltage reference to compare the measured battery voltage against. Preventing battery discharge To switch the Charge Controller on, momentary pushbutton S1 is pressed, allowing current to flow into REG1. IC1 then switches on RLY1, shorting out S1 so that the circuit remains powered after it is released. RLY1 is controlled by digital output RA6 of IC1 (pin 15), which goes high to drive the base of NPN transistor Q3, energising the relay coil via a 56Ω resistor. This resistor reduces the current through the relay coil, as the relay will operate down to 3.75V and so we save a little power this way. Without the resistor, the relay coil current is 28mA, and with it, it is 21mA. The other set of contacts in RLY1 make the connection between the battery and the 51kΩ and 10kΩ battery voltage measuring resistors. If the charger is switched off or a blackout occurs with the battery still connected, the battery powers the Charger Controller and it could become over-discharged and damaged if this continues long enough. With the charger power off, the circuit draws around 50mA from the battery. Fig.7: this scope grab shows the voltage at the gate of Q1 for a single, short pulse. The vertical scale is 2V/div and the horizontal scale is 2.5ms/div. The Mosfet switches on at around 4-5V, so we can determine from this that the switch-on time is around 5ms, while the switch-off time is much shorter, les than 0.1ms (100µs). Australia’s electronics magazine siliconchip.com.au To prevent this, IC1 monitors battery voltage and when the battery voltage falls below 12.5V for a 12V battery or 25V for a 24V battery for at least two hours, the RLY1 switches off. This totally removes the load from the battery, as current can no longer flow from it into REG1 or the voltage divider. Battery voltage measurements When the Charger Controller is powered up, the 51kΩ and 10kΩ resistors allow IC1 to monitor the battery voltage at its an AN3 analog input (pin 2). The resistors reduce the battery voltage to be within its 0-5V measurement range. So for example, if you have a 24V battery at its maximum standard charge voltage of 28.8V, the battery voltage is divided down by a factor of 6.1, giving 4.72V at pin 2 of IC1. The voltage is filtered with a 100nF capacitor to remove noise from the measurement. IC1 converts the voltage to a 10-bit digital value (0-1023), which gives a 29.8mV resolution (5V x 6.1 ÷ 1023). Battery voltage measurements are made when Q1 is switched off, so voltage fluctuations due to the charging current in the leads to the battery don’t affect it. Temperature measurement Fig.8: fit the parts to the PCB as shown above and the photo below. Watch the orientation of the diodes, ICs, LEDs, trimpots and relay. Note that the LEDs should be fitted at right-angles, as shown here, to project through the side of the case. Q1 is fitted last as it’s attached to the bottom of the case before soldering its leads on the top side of the board. Jumper JP1 selects between default or adjustable charging parameters, JP2 enables or disables the absorption phase, and JP3 selects the battery chemistry. An NTC thermistor is used to measure the battery temperature. One thermistor mounts on the PCB and connects to pin 1 of micro IC1 via the switched tip contact of 3.5mm jack socket CON1. When an external thermistor is connected via CON1, the internal thermistor is switched out and the external thermistor connects to pin 1 of IC1 instead. Note that the external thermistor is connected to ground via the ring connection. The sleeve is left open. This allows the metal enclosure of the charge controller to remain floating from the controller circuit. In either case, the thermistor is connected in series with a 10kΩ resistor across the 5V supply. It therefore forms a voltage divider and the resulting voltage, which is related to the thermistor temperature, appears at the AN2 input (pin 1) of IC1 and is converted to an 8-bit digital value. IC1 then uses a lookup table to convert the voltage to a temperature value, as the relationship is non-linear. IC1 can sense whether the thermistor is disconnected, eg, if the wire to the external thermistor is broken. Pin 1 would then be at +5V. Similarly, if the resistor is shorted to ground, IC1 can detect this as pin 1 will be at 0V. The thermistor LED lights in either case, and charging ceases. The thermistor LED flashes when the measured temperature is 0°C or below. Charging also ceases in this case. Set-up adjustments Analog inputs AN5, AN6, AN0 and AN1 (pins 12, 13, 17 siliconchip.com.au & 18) are used to monitor the settings for charge rate percentage, cut-off voltage, float voltage and temperature compensation, as set with trimpots VR1 to VR4. Switch S2 is pressed to store the settings in IC1’s flash. S2 is normally open, and an internal pull-up resistor within IC1 holds the RB5 input (pin 11) at 5V. When S2 is pressed, the pin 11 input is pulled low (to 0V) and this signals the program within IC1 to store the settings for VR2, VR3 & VR4 as the adjustable values for either SLA, lead-acid or Lithium batteries. Australia’s electronics magazine December 2019  31 Fifteen holes are required in the diecast box – eight on the front panel (see below), two on the rear panel (for the cable glands) and five in the base. Four of these are for PCB mounting, with the 6.3mm pillars already shown fitted here. The last hole, just visible in the top right corner, is for mounting Q1 on its insulating washer and bush. And here’s the PCB fitted inside the case with the six LEDs just poking through. As yet, we haven’t fitted the front panel artwork (Fig.9, below). And the wiring we used here was just for testing – polarised 15A auto fig.8 should be used. These values are only stored if the jumper JP1 is in the “adjustable” position. Where the values are stored depends on the position of the battery chemistry selection jumper JP3. This is monitored by IC1’s RA7 digital input (pin 16). Jumper link JP1 sets whether the Charge Controller uses the standard (or default) values or the adjustable settings referred to above. JP2 selects the absorption option. If this jumper is not in the “absorption” position, when charging lead-acid batteries, the charger switches to float charging as soon as bulk charging is complete. For LiFePO4 batteries, in this position, charging ceases as soon as the bulk charge is complete. If absorption charging is enabled by JP2, the absorption phase will run after the bulk charge, provided that the charging process has been going for more than one hour. At the end of the absorption phase, the unit either switches to float charging (for lead-acid) or ceases (for LiFePO4). Since the battery chemistry selection jumper, JP3, can have three possible states, including ‘open’, there is a 10nF capacitor connected from pin 16 of IC1 to ground. IC1 can therefore briefly pull this pin high or low, then cease driving it and sample the voltage at it. If no jumper is inserted, the voltage will be as expected, but if a jumper is in place, it will prevent the capacitor from charging or discharging. LED6 is the battery detection indicator and is driven via transistor Q2 via a 1kΩ resistor from the 5V supply. The base of this transistor connects to the switched side of RLY1’s second set of contacts via a 10kΩ resistor. This transistor switches on when battery voltage is present. This prevents the LED brightness from varying significantly between different battery types. Construction The Charge Controller is built on a PCB coded 14107191, measuring 111 x 81mm. This is housed in a 118 x 93 x 35mm diecast aluminium box. It’s best to start by preparing the box. This way, you can use the blank PCB as a template. First, locate the PCB in the bottom of the box with the edge closest to the LEDs against that edge of the box. Mark out the four corner mounting hole positions, then drill these holes to 3mm and deburr them. Copy the panel artwork (Fig.8) and use it as a template to drill out the holes in the front of the enclosure for the switch, 3.5mm socket and LEDs. Make sure the template is lined up with your PCB mounting location before drilling the holes. The power switch hole is 4.5mm in diameter (5mm is OK) and the thermistor socket is 6.5mm (7mm is OK). The other panel holes are 3mm. You can now start assembling the PCB. Fig.8 shows the overlay diagram, which you can use as a guide during construction. Start by fitting IC2. This is an 8-pin surface mount device that’s relatively easy to solder using a fine-tipped soldering iron. The pin 1 location is marked with a small dot on the Indicator LED driving Power indicator LED1 runs from the 5V supply via a 1kΩ current-limiting resistor. LED2, LED3, LED4 and LED5 are driven from the RA4, RB0, RB1 and RB2 digital outputs of IC1 (pins 3 & 6-8), via 1kΩ resistors. Hole sizes: Fig.9: this front panel artwork can be copied, laminated and glued to the front panel. It could also be photocopied and used as a template for drilling the front panel holes, once you have established the PCB position. You can also download the panel artwork and print it on a laser or inkjet printer – see siliconchip.com.au/shop/11/5095 32 Silicon Chip 4.5 3 6.5 3 3 3 3 3mm SILICON CHIP 12/24V Battery Charge Controller Float Charge + + Power + External Thermistor Australia’s electronics magazine + Thermistor + + + Absorption + Battery siliconchip.com.au LEDS INSULATING SLEEVE M3 NUT Q1 5mm LONG M3 SCREWS SILICONE INSULATING WASHER PCB 6.3mm x M3 TAPPED SPACER BOX 10mm LONG M3 SCREW 5mm LONG M3 SCREWS Fig.10: this diagram clarifies how Q1, the LEDs and the PCB itself are mounted in the case. Note the insulating washer and bush (sleeve) under the M3 nut securing Q1, which are critical, as Q1’s tab must be electrically isolated from the case. package. Line the IC up on the PCB pads and tack-solder one of the corner pins. Check that the IC is still aligned correctly on all the pads. If not, re-heat the solder and adjust again. When aligned correctly, solder all the pins including the original tack-soldered pin. If any pins are bridged together, use flux paste and solder wick to clear the bridge. Next, insert the three M4 screws from the underside of the PCB at each of the eyelet mounting positions and secure using M4 nuts on the top of the PCB. Using a soldering iron, preheat each screw and solder it to the board. Make sure the solder adheres to each screw head. When cool, the nuts can be removed. Note that you may be able to build the unit without having to solder the screw heads if you use M4 copper crinkle washers under each screw head instead, but they are not that easy to find. Construction can now continue by installing the fixed resistors. Take care to place each resistor in its correct position. A colour code table is provided as a guide to finding each value, but it’s best to use a multimeter to check each set of resistors before fitting them as the colour bands can be hard to read. Next, fit the optional PC stakes for the test points labelled TP GND, TP5V and TP1-TP4. They make it easier to attach clip leads during set-up. Then mount the 2-way header for JP1 and the 3-way headers for JP2 and JP3. Now install the diodes and zener diodes, with the orientations and in the positions shown in Fig.8. IC1’s socket can then be installed, and this must also be orientated correctly. Follow with tactile pushbutton switch S2, then jack socket CON1. Push both all the way down onto the PCB before soldering their pins. Fit the on-board NTC thermistor and capacitors next. Note that the electrolytic capacitors must be orientated with the polarity shown. In each case, the longer lead is positive, and the stripe on the can indicates the negative lead. Install transistors Q2 and Q3, then trimpots VR1-VR5, taking care to fit the 100Ω trimpot for VR5. Mount REG1 on the top side of the PCB, with its leads bent down to insert into its pads. Secure the regulator tab to the PCB with a 10mm M3 screw and nut before soldering and trimming the leads. Follow by fitting RLY1, ensuring that its striped (pin 1) end faces to the right as shown. Fuse F1 comprises the two fuse clips and the fuse. The siliconchip.com.au Parts list – Clever Charger 1 double-sided PCB, code 14107191, 111 x 81mm 1 diecast aluminium box, 119 x 94 x 34mm [Jaycar HB5067 or equivalent] 1 2A DPDT 5V coil telecom relay (RLY1) [Altronics S4128B or equivalent] 1 PCB-mount SPDT momentary pubutton switch (S1) [Jaycar SP0380, Altronics S1498] 1 pushbutton switch cap for S1 [Altronics S1482, Jaycar SP0596] 1 SPST micro tactile switch with 0.7mm actuator (S2) [Jaycar SP0600, Altronics S1122] 1 PCB-mount 3.5mm stereo switched socket (CON1) [Altronics P0092, Jaycar PS0133] 2 PCB-mount M205 fuse clips (F1) 1 10A M205 fuse (F1) 2 NTC thermistors (10kW at 25°C) (TH1 and external thermistor) 1 2-way header with 2.54mm spacing (JP1) 2 3-way headers with 2.54mm spacing (JP2,JP3) 3 jumper plugs/shorting blocks (JP1-JP3) 1 18-pin DIL IC socket (for IC1) 1 3.5mm stereo jack plug 1 TO-220 silicone insulating washer and mounting bush (for Q1) 4 6.3mm-long M3 tapped spacers 3 M4 x 10mm machine screws 3 M4 star washers 3 M4 hex nuts 2 M3 x 10mm machine screws 8 M3 x 5mm machine screws 2 M3 hex nuts 4 insulated crimp eyelets (wire size 4mm, eyelet for M4 screw) 2 cable glands for 4-8mm diameter cable 1 2m length of 15A figure-8 automotive cable 1 1m length of twin-core shielded cable (for thermistor) 1 20mm length of 6mm diameter heatshrink tubing 2 large insulated battery terminal alligator clips (red and black) 6 PC stakes (optional) 4 small adhesive rubber feet Semiconductors 1 PIC16F88-I/P micro programmed with 1410719A.HEX (IC1) 1 Si8751AB-IS isolated FET driver (IC2) [Silicon Chip Online Store Cat SC5102] 1 LM317T 1.5A adjustable positive regulator (REG1) 1 IRF1405N N-channel Mosfet (Q1) 2 BC337 NPN transistors (Q2,Q3) 3 green 3mm LEDs (LED1,LED5,LED6) 2 orange 3mm LEDs (LED2,LED4) 1 red 3mm LED (LED3) 2 18V 1W zener diodes (ZD1,ZD2) 3 1N4004 1A diodes (D1-D3) Capacitors 1 220µF 50V PC electrolytic 1 100µF 16V PC electrolytic 5 100nF MKT polyester 5 10nF MKT polyester 1 10pF ceramic Resistors (all 0.25W, 1% metal film unless otherwise stated) 1 100kW 1 51kW 3 10kW 1 3.3kW 1 2kW 7 1kW 1 330W 1 120W    1 100W 1W, 5% 1 56W 4 10kW multi-turn top adjust trimpots, 3296W style (VR1-VR4) (code 103) 1 100W multi-turn top adjust trimpot, 3296W style (VR5) (code 101) Australia’s electronics magazine December 2019  33 TO BATTERY TO CHARGER Fig.11: once the PCB is mounted in the case, wire it up as shown here. Make sure that the crimp eyelets are firmly secured to the board using the specified washers and nuts. CABLE GLANDS + SILICON CHIP 4004 COIL 19170141 18V 18V 4004 + 4004 It is placed so that the metal face will sit at the base of the enclosure. Note that the tab of Q1 must be at least 1mm away from the back edge of the case, to prevent the tab shorting to 14107191 it. Test that it is in the right position by REV.B temporarily mounting the PCB in poC 2019 sition and mark out the mounting hole for Q1. Also mark out the two holes for the cable glands. 1 Then remove the board, drill the Mosfet mounting hole to 3mm and deburr. Also drill the cable gland holes and check that they fit securely. The Mosfet is secured with a 10mm M3 machine screw and nut. If you find it awkward to secure it, the screw can be fed in from the top instead. Q1’s tab must be isolated from the case by an insulating washer and mounting bush. For details, see Fig.10. Now check that the tab of Q1 is insulated from the metal box by measuring the resistance between the two with a multimeter. The reading should be high, above 1MΩ. The box is isolated from the electrical connections so that accidental contact of the box to a battery terminal will not cause a short circuit. The PCB can now be mounted inside the box using the remaining M3 screws in from the base of the enclosure into the spacers. Fit the two cable glands and feed the figure-8 cable through them, ready to attach the crimp eyelets. We used the striped side of the wire as the negative and the plain wire as the positive, but some people prefer the opposite. Just make sure you’re consistent. Attach the crimp eyelets to the wire using a suitable crimping tool and secure them to the PCB using the M4 nuts and star washers. Make sure the eyelets are not shorting to adjacent parts, especially the fuse holder. Attach the large insulated clips to the end of the battery leads; red for positive and black for negative. The Charge fuse clips must be orientated so that the end stops are facing outwards, so that the fuse can be clipped into place. Make sure they’re sitting flat on the PCB and then attach them using a hot iron and plenty of solder. The LEDs are mounted at right angles to the PCB. Bend the leads 11mm back from the front lens of each, taking care to have the anode (longer lead) to the right and then bend the leads downward. Insert into the PCB and solder them so that the bottom of the lenses are 6mm above the top surface of the board. Now mount pushbutton S1, ensuring it is pressed down firmly onto the board before soldering its pins. Secure the tapped spacers to each corner of the PCB using 5mm M3 screws, then mount Q1. It’s fitted to the underside of the PCB and bolted to the case for heatsinking. Bend Q1’s leads up at right angles, as shown in Fig.10. Resistor Colour Codes     Qty. Value  1 100kΩ  1 51kΩ  3 10kΩ  1 3.3kΩ  1 2kΩ  7 1kΩ  1 330Ω  1 120Ω  1 100Ω 1W  1 56Ω 34 Silicon Chip 4-Band Code (1%) 5-Band Code (1%) brown black yellow brown brown black black orange brown green brown orange brown green brown black red brown brown black orange brown brown black black red brown orange orange red brown orange orange black brown brown red black red brown red black black brown brown brown black red brown brown black black brown brown orange orange brown brown orange orange black black brown brown red brown brown brown red black black brown brown black brown gold (5%)     n/a green blue red black brown green blue black gold brown Australia’s electronics magazine Small Capacitor Codes Qty. Value µF Value  5 100nF 0.1µF  5 10nF 0.01µF  1 10pF n/a IEC code 100n 10n 10p EIA code 104 103 10 WHERE DO YOU GET THE BITS? The PCB, programmed PIC16F88 and the isolated FET driver are all available from the SILICON CHIP ONLINE SHOP (siliconchip.com.au/ shop). All other components should be available from your normal parts supplier(s). siliconchip.com.au Controller leads can be terminated in bare copper, for clamping in your charger clips, or they can be permanently wired to the charger. Finally, push the button cap onto S1 and fit the four stick-on rubber feet to the underside of the box. value than the battery’s actual capacity. This is because the Ah capacity usually requires much less current from the battery, over a longer period. Preparing the external thermistor For most large batteries, you would set the charge rate to 100%. To do this, adjust VR1 to get a reading of at least 1V at TP1 relative to TP GND. You can use the 100% setting for all batteries that can accept the full charge rate from your charger. If you need a lower current than your charger would normally supply, as explained above, adjust VR1 to reduce the maximum charge rate. This still applies the full current from the charger to the battery but in bursts. For example, when the charge percentage is set at 50%, the charge will be bursts of full current for 50% of the time. This would be suitable, for example, with a charger that is rated at 4A and a battery that can only accept a 2A charge current. Divide the desired charge rate percentage by 100 and adjust VR1 to get this voltage at TP1. So for our 50% example, you would adjust for 0.5V at TP1. Note that when charging a 12V battery that initially has less than 10.5V across its terminals, or a 24V battery with less than 21V, the actual charge rate will be 1/10th of that set. So for example, if you have set the charge rate to 100%, it will be charged with a burst for 200ms every two seconds. During this process, the Charge, Absorption and Float LEDs flash. The NTC thermistor on the PCB gives acceptable results with the Charge Controller close to the battery, as the metal box will not usually heat up too much above ambient temperature. As a consequence, its temperature should be similar to the battery temperature. But a thermistor on the battery is going to give more accurate results and therefore a safer and more complete charge. To make this external thermistor, a stereo 3.5mm jack plug is soldered to one end of the twin core cable, with the thermistor soldered across the wires at the other end. For the jack plug, connect the internal wires to the tip and ring terminals, and the wire sheath to the jack plug sleeve. The thermistor can be covered in heatshrink tubing and attached to the side of the battery using adhesive-backed hook-and-loop tape (eg, Velcro) or good quality doublesided tape for a more permanent installation. Testing Before applying power, it is vital to adjust VR5 to its lowest resistance by turning the adjusting screw 20 full turns anti-clockwise. You can check that this has been done correctly by measuring the resistance between TP GND and the 330Ω resistor at the end near the cathode of ZD1. The resistance should be near to 0Ω. This prevents REG1 from producing more than 5V when power is first applied. Now connect a multimeter set to read DC voltage between TP GND and TP5V. Connect a power supply to the charger input (eg, a 12V DC plugpack or bench supply), press and hold S1 and adjust VR5 for a 5.0V reading on the multimeter. Check that the voltage between the pin 5 and pin 14 pin on IC1’s socket is also 5V. If so, switch off power and insert IC1, taking care to orientate it correctly and make sure all its pins go into the socket and don’t fold up under the IC body. Plug jumpers into JP1, JP2 and JP3 as required for your battery. Determine the maximum safe charging current Most lead-acid batteries can accept up to 30% of the quoted Ah capacity as charge current. For example, a 30Ah battery can be charged at 9A. In this case, as long as your charger is rated at no more than 9A, the 100% setting can be used. If your battery is rated in RC (reserve capacity), you will need to convert to Ah to calculate its maximum charge current. Reserve capacity indicates how many minutes a fullycharged battery can deliver 25A before the voltage drops significantly. A battery with an RC of 90 will supply 25A for 90 minutes. The amp hour specification (Ah) refers to the total current that can be supplied over a long period, usually 20 hours. So a 100Ah battery can supply 5A for 20 hours. To convert from RC to Ah, multiply the RC value by 0.42, which is the same as multiplying by 25A to get the capacity in Amp minutes, then dividing by 60 to convert from minutes to hours. In practice, because the RC capacity specification uses 25A, the conversion from RC to Ah often gives a lower Ah siliconchip.com.au Setting the charge current Charge Controller limitations To round out our description of this project, we should also mention its possible shortcomings. These do not matter in most cases, but may be significant in specific charging applications. (1) Pulsed operation The pulsed charging current can cause extra heating within the battery as losses are proportional to the square of the current. For example, when charging at an average of 1A from a 4A charger, a 25% duty cycle is used. This averages to 1A, however, the losses are equivalent to charging at 4A2 x 25% = 4 times that of charging at 1A continuously. (2) Absorption and float charge Because we pulse the charge current, the battery voltage fluctuates during charging. We measure the battery voltage just after the charge pulse finishes. Compared to a charger that has continuous charging at a lower current, the battery voltage may be maintained at a different value. (3) Charge indication As the battery supplies the circuit power via Q1’s body diode, it can appear that charging is taking place even when the charger is not connected or powered. It is important to check that the charger is connected and is switched on when you start charging. (4) Battery discharge If the ‘dumb’ charger is switched off with the battery connected, the battery will eventually discharge due to the 50mA load of the Charge Controller. This is prevented using a relay to switch off the power to the charge controller if the battery voltage drops too low, but if this happens, you will have to recharge the battery. Australia’s electronics magazine December 2019  35 Once the voltage comes back up into the normal range, full rate charging will start. Current limiting Very small batteries may not tolerate these high-current bursts, even if they are limited in time. In this case, you could add a series power resistor between the Charge Controller and your battery. For example, when using a 12V battery and with a charger that typically provides up to 17V peak, there will be 5V peak across the resistor. So the resistor value required is 5V divided by the peak current that the battery can tolerate. If the peak current is 1A, then the resistance can be 5Ω (eg, one 4.7Ω resistor or two 10Ω resistors in parallel). Its wattage rating will need to be 5V squared (25) divided by 5Ω. That gives us a 5W dissipation, so to be safe, you would use a 4.7Ω 10W resistor, or two 10Ω 5W resistors in parallel. This is a conservative figure since 5W is the peak power, not necessarily the average power. The actual RMS voltage across the resistance will be around 30% lower than this, so the dissipation will be around 50% lower. Therefore, you could probably get away with a 5W resistor. As mentioned, the charge LED can be set to flash when current is applied during the absorption and float phases. This indicates the duty cycle used to charge the battery. If the LED is off, then the battery is over the required voltage for absorption or float. If the LED is not lit very often, then the battery is at the required voltage. If the LED is lit continuously, then the battery voltage is still being brought up. LED option setting The flashing LED option is on initially. If you do not require the charge LED to show during these phases, you can disable this. Switching off power and holding S2 while the power is re-applied using S1 will disable this feature. The change is acknowledged by a minimum of two fast (two per second) flashes of the Charge LED. The acknowledgement flashing continues until S2 is released. You can re-enable the feature by holding S2 again at power up. Setting the parameters Most battery manufacturers will specify the required cut-off voltage (also called the cyclic voltage) for a given battery. For lead-acid types, the manufacturer will typically also specify the float voltage (also called the trickle voltage) and the temperature compensation coefficient. Note that the cut-off and float voltages must be the values specified at 20°C. The temperature compensation required by manufacturers is usually shown as a graph of voltage versus temperature. You can convert this to mV/°C by taking the difference between the voltages at two different temperatures and divide by the temperature difference. For example, a battery graph may show the cut-off or cyclic voltage at 0°C to be 14.9V. At 40°C, it may be 14.2V. So (14.2V - 14.9V) ÷ 40°C = -700mV ÷ 40°C = -17.5mV/°C. Where the float temperature compensation is different from the cyclic temperature compensation, a compromise between the two values will have to be made. Note that you can do this calculation over a smaller temperature range if that is consistent with the temperatures under which you expect to be charging the battery, eg, 1035°C if you live in coastal Sydney. To set the adjustable parameters, apply power to the Charge Controller via a battery or charger and select the battery type with JP3. Then connect a multimeter between TP2 and TP GND and adjust for one-tenth of the required cut-off voltage using VR2. So 1V at TP2 represents a 10V cut-off, 1.44V sets it to 14.4V etc. Now monitor the voltage at TP3 and adjust VR3 for the required float voltage with the same 10:1 ratio. For the temperature compensation, monitor TP4 and adjust VR4 for the required compensation, with 1V representing -10mV/°C. So 5V represents -50mV/°C and 2V represents -20mV/°C etc. Once you’ve adjusted all these, make sure JP1 is inserted and then press S2 to store the values. The Thermistor, Charge and Float LEDs will all flash twice to acknowledge that these values have been stored successfully for lead-acid batteries. If adjusting the thresholds for LiFePO4 batteries, just the charge LED and absorption LED will flash. You can store the parameters for each battery type by changing the settings for JP3 and readjusting the trimpots, then store the values again using switch S2. Adjusting the trimpots without pressing S2 has no effect. The adjustment of VR1, for the charge rate, is different. This has an immediate effect. You will have to re-adjust it each time you switch to charging a different battery that needs a different charge rate than the last one. SC The SILICON CHIP READY RECKONER Gives you instant calculation of Inductance - Reactance - Capacitance - Frequency It’s ESSENTIAL For ANYONE in ELECTRONICS You’ll find this wall chart as handy as your multimeter – and just as useful! Whether you’re a raw beginner or a PhD rocket scientist . . . if you’re building, repairing, checking or designing electronics circuits, this is what you’ve been waiting for! Why try to remember formulas when this chart will give you the answers you seek in seconds . . . easily! Read the feature in the Januar y 2016 issue of SILICON CHIP (you can view it online) to see just how much simpler it will make your life! All you do is follow the lines for the known values . . . and read the unknown value off the intersecting axis. It really is that easy – and fast (much faster than reaching for your calculator! Printed on heavy (200gsm) photo paper Mailed flat (rolled in tube) or folded Limited quantity available Mailed Folded: Mailed Rolled: $20.00 inc P&P & GST ORDER NOW AT www.siliconchi p.com.au/shop $10.00 inc P&P & GST 36 Silicon Chip Australia’s electronics magazine HU 420x59G4Em on heavy photo pa m per siliconchip.com.au Altronics M Article by Tim Blythman W e described the original Mega Box Arduino Prototyping System in our December 2017 issue (siliconchip.com.au/Article/10902). Then later, in February 2018, we used it to create an improved version of our Arduino Music Player (siliconchip. com.au/Article/10976). In case you missed those articles, the Mega Box allows you to plug in an Arduino board and up to two shields. It provides many extra useful functions like an LCD screen, illuminated pushbuttons, a rotary encoder, relays etc and it all fits into a plastic ‘half rack’ instrument case which comes pre-cut with all the holes needed in the front and rear panels. The result is a very neat package which can be programmed in the same way as any other Arduino device. It saves you a lot of effort in putting together the parts you need to make a slick Arduino project. It solves a big problem that Arduino has; while you can easily build a project by stacking an Arduino board with some shields, then running jumper wires to other modules and parts, the result is an unholy, tangled mess which looks very unprofessional. But you can build the same project 38 Silicon Chip just as easily (if not more so) using the Mega Box, and the result is neat, slick and professional looking. So what’s not to like? This updated version adds several useful new features, which we’ll describe shortly. The front panel of the case carries Altronics’ “Inventa” branding, which is their home brand for Arduino-related products. You might have seen the article we published in October on Home Automation using two Arduino wallplates, also from the Inventa range (siliconchip.com.au/Article/12023). As well as describing the new Mega Box V2 (also referred to as the Mega Box Mark II in some places), we’re also going to provide full instructions for building it. Our instructions expand on those provided with the kit, which should make construction easier, and also help you figure out how to use it. For example, the Altronics instructions we received did not provide a list of parts supplied in the kit (which should be rectified in later versions), so we’re publishing a full parts list at the end of the article in case you need it. Once you’ve built the Mega Box V2, you will need the Arduino IDE (integrated development environment) software to program it. The latest verAustralia’s electronics magazine sion can be downloaded for free from: http://siliconchip.com.au/link/aatq We’re currently using version 1.8.5. While the Mega Box will work with an Arduino Uno or similar form factor board, to take full advantage of its capabilities, you really need an Arduino Mega or similar. Mega Box V2 features From the outside, the Mega Box V2 looks almost the same as the original; it’s built into the same case (Altronics Cat H4996), so it’s the same size when finished, although the front panel has been rearranged. There are also some new connections at the rear of the case. Inside is where most of the changes have occurred. The biggest of these is the addition of a second set of shield headers, meaning that a second shield can now be fitted. You could fit more than one shield with the original Mega Box, but only if you left the lid off! That sort of defeats the purpose of using a nice case like this. There are now five relays instead of two. These are rated at 2A/30V DC, and a ULN2003 Darlington transistor array now controls all the relays. They are Altronics Cat S4128C double-pole relays, but only one set of contacts is siliconchip.com.au Mega Box V2 An Arduino Prototyping System Movie sequels are rarely as good as the original, but that is not the case here. The Altronics Mega Box V2 has more of everything you might need to prototype your next Arduino project. Features • Five 2A/30V DC relays controlled by a ULN2003 Darlington transistor array • A rotary encoder • 160-pad prototyping area • Eight opto-isolated digital input signals rated up to ±24V • An IR receiver for use with a remote control • Fits two Arduino shields minimum, or however many you can stack. • Four illuminated momentary pushbuttons • 16 x 2 character LCD with PWM backlight • Uses an Arduino Mega, Uno, or similar broken out from each to a set of pluggable terminal blocks. Apart from the relay contacts, the extra connections on the rear of the case are for up to eight opto-isolated digital input signals. These feed into a pair of LTV-847 quad opto-isolators before being buffered by a pair of 74HC14 quad Schmitt trigger inverters. These could be useful to interface with external circuitry running from a different (and possibly isolated) power supply. As for the original Mega Box, all the peripheral connections are brought out to header sockets on the PCB. Nothing is committed to any pins on the main processor board, giving complete flexibility in the way everything is wired. This is apparent in the Mega Box V2 circuit diagram, which is shown in Figs.1 & 2. Note the extensive use of headers for connecting the various optional sections of the circuit back to the Arduino’s I/O pins. The Mega Box V2 also includes better support for 3.3V Arduino boards and more flexible front panel button wiring options. But it’s the extra shield slot, added relays and isolated inputs that really set it apart. The only reduction in features with the newer board is the prototyping siliconchip.com.au area, which has dropped from 210 pads down to 160 pads, although this could easily be compensated for by fitting a prototyping shield in the extra shield slot. On the front panel, it has four illuminated momentary pushbuttons, an IR receiver, a rotary encoder and a 16x2 character LCD. Inside the case are a pair of user-defined LEDs which can also be connected by jumper wires to any I/O pin. LED3 inside the case is connected to D13 of the Arduino module header, as is common these days. Jumper JP1 is provided to allow one pin of each front panel switch to be connected to GND, so that you only need to run a single jumper wire back to an Arduino pin to sense presses of that button. JP2 (shown in Fig.2) allows each end of the eight opto-isolated inputs to be connected or disconnected from the external terminal blocks. Note how many of the components are powered from the Arduino module’s IOREF pin. This means that they are powered from 5V if it’s a 5V micro, or 3.3V if it’s a 3.3V micro, so their inputs and outputs can be connected directly to Arduino I/O pins. Four fiveway headers are provided to make it easy for you to tap into the 3.3V, 5V, Australia’s electronics magazine GND and Vin (external DC input) rails. Because the reset button on the Arduino processor board is covered up when the board is installed, a separate tactile switch is provided (S1). The LCD module itself plugs into CON5, with all of its pins brought out to CON4, so that they can be connected to the Arduino (or elsewhere) as needed. Trimpot VR1 provides display contrast adjustment while CON19 and the first inverter in IC8 give the option for software backlight control. Construction As mentioned above, instructions are provided with the kit, and these are certainly sufficient for building it, which is not an overly difficult task. However, we thought that beginners would appreciate a bit more detail, so we’ve prepared a PCB overlay diagram to guide you, shown in Fig.3. Keep in mind that the following instructions, along with those supplied by Altronics, are for building the Mega Box V2 as a prototyping platform. But if you have a particular task in mind, you could consider eliminating some or all of the sockets and soldering hookup wires directly to the pads on the board. December 2019  39 40 Silicon Chip Australia’s electronics magazine siliconchip.com.au Fig.1: this diagram shows most of the circuitry in the Mega Box V2; the rest (for the new opto-isolated inputs) is in Fig.2. It is dominated by the connections between the main Arduino module (MODULE 1) and the two shield sockets. There is also an extra set of sockets for all the Arduino pins, including the Arduino Mega-specific pins, so that you can connect them to other components such as LEDs, buttons etc via jumper leads. siliconchip.com.au Australia’s electronics magazine December 2019  41 Fig.2: the eight opto-isolated inputs are between pin pairs on pluggable terminal blocks CON1 and CON2. These can withstand up to ±24V, with +1.5-24V corresponding to ‘on’. The outputs at the collector pins of IC1 and IC2 are inverted, and these are then buffered and re-inverted by hex inverters IC3 & IC4. The eight single-ended isolated signals are available for sensing at CON6. This could give a neater end result, as you could cut the wires to the minimum lengths required, rather than using fixed-length jumper leads. We won’t describe that approach in detail, but it’s worth keeping in mind. There is also less hassle in not needing to fit as many headers. Obviously, this is a much more permanent and less easily changed approach. So we only suggest it for confident constructors. If you’re doing that, you could also save time by leaving off any components you won’t be using. By the way, the kit doesn’t come with any jumper wires. It’s designed mainly with male-male jumpers in mind. So you might want to pick up a pack of these when you purchase the kit, such as Altronics Cat P1016 (65 pieces, each approximately 160mm long). You might also find Altronics Cat P1017 handy, as it includes 30 male/ female and 30 female/female jumpers, some of which may be required (depending on your application). If you are going to use the Mega Box as a prototyping platform, we suggest fitting all the components, as it will 42 Silicon Chip be much harder to do this later. This is mainly because some components, particularly the headers, can be difficult to hold in place while soldering if added after taller components have already been mounted on the board. To make it easier to solder the components to the PCB, the instructions generally proceed in order of lowest to highest profile components, meaning that when the board is inverted, the components you are fitting are held in place by your bench surface. The right-angle header socket for the LCD is the lowest-profile part, so we recommend fitting it first. But it’s best to solder the LCD's header on first, so that you can plug this into the PCB socket before soldering it. This allows you to check that the LCD will sit perpendicular to the main PCB before fixing the header socket in place. Note that the PCB silkscreen shows trimpot VR3 overlapping with the LCD header, but in reality, VR3 is much smaller than indicated, so there is no collision. Proceed now by fitting the resistors, followed by diodes D1-D8, the IC sockets, pushbutton S1, the relays and the single trimpot VR1. Rather than trying Australia’s electronics magazine to place many parts on the PCB and then solder them all at once, we suggest that you just fit a few at a time (or one at a time). When it comes to fitting the resistors, note that the 330W resistor on the PCB shown in the Altronics instructions has been replaced with a wire link here. That’s because the 330W value results in a very dim LCD backlight. A wire link (one is supplied) is acceptable but may severely shorten the backlight lifespan due to high current, meaning a lower-value resistor like 33-47W would be better. Later versions of the kit will probably be supplied with such a resistor. Also, note that some 1kW resistors on the board need a 0.25W rating while some have a 0.6W rating. All the 0.6W resistors are mounted next to JP2, and they are marked as being 0.6W types in Fig.3. This allows up to 24V to be applied to the opto-isolated inputs. The next job is probably the most time-consuming: fitting all the headers. Some of them are supplied in long strips and will need to be snapped or cut to length. For the regular pin headers, usually you can snap these easily by holding one side with pliers and siliconchip.com.au This is how the completed Mega Box V2 PCB looks. We have fitted all the jumper shunts as most user applications will also need to do so. The manual also suggests using some short lengths of wire to brace the LCD in position, which we haven’t done (yet). then using a second pair of pliers, or your other hand, to snap off the unwanted length. But for the header sockets, it’s a more involved process as you will need to use side cutters or similar to cut down the middle of one pin (sacrificing it), then clean up the remaining plastic housing of that pin with a small file to give you a neat socket of the right length. Luckily, this is not required for the 6-way, 8-way or 10-way sockets as these are supplied ready to install. When it comes to installation, if you have an Arduino and some shields (which surely you do, if you’re building the Mega Box V2), you can use them as jigs to plug the headers/sockets into before feeding them all into the board and soldering them all at once. This helps keep everything nice and square, and prevents the headers from moving about as you’re mounting them. But that only works for the headers for the Arduino and its shields. The remainder will need to be installed one at a time. Check Fig.3, the photo above and the Altronics instruction sheet to see which headers should be male and which female. If you want to do a neat job, it’s best to solder just one pin of each header first, then flip the board over and check that it’s straight before soldering the siliconchip.com.au other(s). If it isn’t correctly aligned, you can re-heat the solder joint and carefully nudge it into position. Many of the female sockets scattered around the board are designed so that you can use a male-male jumper leads to connect the two points. So if you know what you’re doing and have plenty of female-female jumper leads on hand, you could substitute regular pin headers there. But if you aren’t sure, we suggest fitting them as Altronics have indicated, and as we have shown here. Once the headers are in place, it’s a good time to fit the single electrolytic capacitor and the three LEDs. These are all polarised; the capacitor’s longer lead goes towards the + sign on the PCB, while the stripe on its can indi- cates the negative side. Similarly, the LEDs have a longer lead which goes into the pad marked “A” in Fig.3, while the flat on the lens indicates the negative lead (cathode). While Altronics suggest that LED1 should be green and LED2 plus LED3 be red, we fitted the green LED for LED3 and red for LED1 and LED2. Ultimately, it’s up to you. These LEDs are not visible with the lid on the case anyway, so they are most useful for debugging. Now attach the four pushbuttons (S2-S5), the rotary encoder and the IR receiver along the front edge of the PCB. Take a moment to ensure that they are square and straight before soldering; these are some of the few components visible from outside the case. The Mega Box V2 does well to hide its Arduino interior. Only those in the know would suspect that the DC jack and USB socket are part of an Arduino Mega board. The knockout panels above the screw terminals can be used to make connections to either or both of the shields fitted, if required. Australia’s electronics magazine December 2019  43 Now plug the five ICs into their sockets. Their footprints are marked with their designations, so it is easy to check that the correct IC is being installed in the correct socket. As usual, make sure that their pin 1 dot or notch goes towards the notched end of the socket. This is also a good time to plug the LCD screen into CON4. It sits on top of the PCB, at right-angles. Four solder pads are provided in front of and behind the LCD. You can solder tinned copper wire ‘hoops’ between these pads (along the dashed red lines) to help hold the LCD firmly in place, although we didn’t bother, as the socket seemed to do a reasonable job holding it to our unit. Final assembly Fig.3: this diagram shows the recommended location and type of all components on the board. As mentioned in the text, depending on how you plan to use it, some components could be left off, and some connections could be made via wires soldered directly to pads on the board rather than via headers. You should also fit the 16 jumper shunts to the optoisolator headers (near the rear of the PCB) and four jumper shunts to the pushbutton headers (near the front). We can’t see any reason for not fit44 Silicon Chip ting the former from the start, and you’ll most likely want the latter in place too, to make it easier to detect a button press from a micro pin (in combination with an internal pin pull-up current). Australia’s electronics magazine Before testing our newly assembled Mega Box V2, we decided to mount it in the supplied enclosure. Although not mentioned in the instructions, we fitted the supplied rubber feet to the enclosure first. They prevent the unit from sliding around on the bench. The supplied instructions also suggest fitting the front of the case now, but we found it easier to leave it off initially, as it gets in the way of plugging jumper leads into the sockets near the front of the PCB. In this state, the unit is well set up for testing and prototyping. To complete the assembly (as you would do after finalising your software and internal wiring), the front and rear case parts are fitted and secured with the included countersunk screws. Once the front panel is in place, you can attach RE1’s knob. You might find it easier to screw in the countersunk screws before installing the panels. This ensures that the threads cut in the plastic by the screws are tapped straight and square. Also be aware that you need to unplug the pluggable terminal blocks from the rear of the unit before attaching the rear panel. You can plug them back in once you’ve done that. The partial knock-outs in the rear panel are optional and need only be removed if you are using a shield which is too long to fit inside the enclosure, or needs extra wire connections to go to the outside world. For example, these could be used to feed through an Ethernet cable to plug into an Ethernet shield. siliconchip.com.au Naturally, the final step is to fit the top panel. For subsequent testing and debugging, simply remove this panel to gain access to the Mega Box internals. We found this case very easy to work with. Testing it and trying it out The sample sketch can be downloaded from: siliconchip.com.au/ link/aauv It requires two external libraries to work; a third library (for the LCD) is included with recent versions of the Arduino IDE. So make sure yours is up-to-date (see the link in the intro). As the Mega Box V2 instructions note, practically all the remaining functions provided by the board can be accessed by reading from and writing to digital pins, with simple calls to digitalRead() and digitalWrite(). The two libraries used by the sample code are for infrared reception and decoding the pulses from the rotary encoder. These can be installed using the IDE’s Library Manager. They can be found using the search terms “irremote” and “encoder”. To use this sample sketch, you need an Arduino Mega and 14 malemale jumper leads. You will find that you have to push pretty hard to plug in the Mega; there are around 80 pins that you need to force into their sockets. To test the infrared receiver, you’ll also need an Altronics A1012 universal remote control programmed to code 089, or another universal remote using a similar Philips TV profile. The demo sketch describes the wiring connections that are assumed in the code; see the comments at the top of the sketch. If you only have an Arduino Uno or similar, substitute pins A0-A5 for pins D14-D19. It may even be possible to use other boards like the Leonardo, but you will have to figure out the differing pin mapping. It may be easiest (and possibly necessary) to change the pin assignments near the start of the sketch to suit the board you are using. Open the sketch, ensure that the correct board (Uno or Mega) and serial port are selected in the Tools → Board and Tools → Port menus respectively, then click Upload. If you can’t see anything on the LCD, you may need to adjust contrast potentiometer VR1. If you see solid dark blocks on the LCD, try rotating VR1 clockwise; othsiliconchip.com.au Parts List – Altronics Mega Box V2 1 plastic half-rack case with custom cut front and rear panels, feet and screws [H4996] 1 double-sided PCB, coded K9670A, 198 x 115mm 1 16x2 alphanumeric LCD [Z7013] 3 40-way female header sockets [P5390] 1 20-way right-angle female header socket [P5392] 1 2x40-way female header socket [P5394] 2 40-pin male headers [P5430] 2 2x40-pin male headers [P5410] 2 6-way female headers [P5374] 10 8-way female headers [P5375] 3 10-way female headers [P5376] 20 jumper shunts/shorting blocks (for JP1 & JP2) [P5450] 2 8-way right-angle pluggable terminal blocks (CON1,CON2) [P2678, P2658] 1 9-way right-angle pluggable terminal block (CON3) [P2679, P2659] 1 6-way right-angle pluggable terminal block (CON7) [P2676, P2656] 1 4.3mm vertical tactile pushbutton switch (S1) [S1120] 4 PCB-mount right-angle pushbutton switches with integral LEDs (S2-S5) [S1190 (red) or S1192 (green)] 5 5V DC coil, 2A DPDT telecom relays (RLY1-RLY5) [S4128C] 1 PCB-mount right-angle rotary encoder switch (grey code) (RE1) [S3350] 1 47uF 16V electrolytic capacitor [R5102] 5 M3 x 6mm plastic tapping screws (for mounting PCB in case) 1 10.5mm diameter, 12mm long black aluminium 18T spline knob (for RE1) 3 16-pin dual-wipe IC sockets (for IC1, IC2 & IC8) [P0565] 2 14-pin dual-wipe IC sockets (for IC3, IC4) [P0560] 1 length of tinned copper wire 1 length of solder Semiconductors 2 LTV-847 quad transistor output optocouplers, DIP-16 (IC1,IC2) 2 74HC14 hex inverters, DIP-14 (IC3,IC4) [Z8514] 1 ULN2003 Darlington array IC, DIP-16 (IC8) [Z3000] 1 3-pin 3.3V/5V infrared receiver/decoder (IRD1) [Z1611A] 1 green 5mm LED (LED1) [Z0801] 2 red 5mm LEDs (LED2,LED3) [Z0800] 8 1N4004 400V 1A diodes (D1-D8) [Z0109] Resistors (all 1/4W, 1% metal film) 12 10kW 7 1kW 8 1kW 0.6W 1 330W*not used, see text 1 47W 1 0W (link) 1 10kW mini horizontal trimpot [R2480B] 1 Universal remote control [Altronics A1012 or similar] is recommended. erwise, turn VR1 anti-clockwise. The demo is quite basic. Buttons on the remote will toggle the LEDs on the pushbuttons on the Mega Box. The rotary encoder will change the displayed number of the LCD and change the backlight brightness. To do much more, you will have to write your own code. Summary The Mega Box V2 does everything the original Mega Box could do and more. It now supports two shields, has five relays and eight opto-isolated inputs too. And most importantly, as Australia’s electronics magazine we said in the intro, it turns a messy prototype into a slick, professionallooking unit. One minor quibble we have with the Mega Box V2 design is that we would have preferred to have the pushbuttons and rotary encoder on the right and the LCD on the left. This would make the unit more ergonomic for right-handed individuals; after all, the majority of people are right-handed or ambidextrous. The full kit is available from Altronics (K9670A) for $120, including GST, or $210 for two at: siliconchip.com. au/link/aaxp SC December 2019  45 HOW IT WORKS: Toyota’s hybrid system has been used on many different models of car, from the original Prius which debuted in 1997, through to the Hybrid Camry, Corolla, RAV4, various Lexus models and even vehicles from other manufacturers. It’s the most successful (and arguably the best) vehicle hybrid system, and it’s very clever. This is how it works. T oyota’s Hybrid Synergy Drive is built around an internal combustion engine (ICE) which runs on the Atkinson cycle (rather than the Otto cycle used in most spark-ignition ICEs), two electric motor/generators and a battery pack. The genius in this arrangement is the use of two electric motors and a ‘power split device’ or PSD, to control how power flows through the system. This article describes the system used in the 2015 hybrid Camry. The basic arrangement is shown in Fig.1. The PSD is a planetary gear system with a sun gear, planet gears, a planet gear carrier and a ring gear. The 46 Silicon Chip ICE is connected via the gear carrier and planet gears, while MG1 is connected via the sun gear, and the vehicle’s wheels (via gears and the differential) are connected via the ring gear. The PSD’s ring gear is also connected to another planetary gear system, used as a reduction gear for the second motor/generator (MG2). Both motor/ generators are three-phase permanent magnet types. For forward motion, a combination of the ICE, MG1 and/or MG2 can provide power, while reversing is handled solely by MG2, which simply reverses by Roderick Wall Australia’s electronics magazine its direction of rotation. The PSD splits power from the ICE between the wheels and motor/generator 1 (MG1). How the energy is split depends on the electrical load on MG1. A greater electrical load on MG1 causes more ICE energy to go to the wheels, and less to MG1. Thus, there is no ‘gearbox’ as in most other (non-electric) vehicles; not only is no reverse gear needed, as described above, but due to the way the PSD operates, there’s no need to change gears as vehicle speed increases. Electronic CVT Toyota refers to this system as an siliconchip.com.au ENERGY MONITOR HIGH VOLTAGE BATTERY ENGINE WHEELS ELECTRONICS MG1 INVERTER HV BATTERY MG2 INVERTER ENERGY TO MG1 (MOTOR/GENERATOR 1) IS VIA SUN GEAR OF POWER SPLIT DEVICE (BLUE) POWER SPLIT DEVICE (PSD) REDUCTION GEAR SET INTERNAL COMBUSTION ENGINE (ICE) MOTOR/GENERATOR 1 (MG1) FRONT WHEEL 20 1 9 ENERGY FROM INTERNAL COMBUSTION ENGINE (ICE) TO POWER SPLIT DEVICE (PSD) IS VIA PLANET GEAR CARRIER (YELLOW) AXLE AXLE SC  MOTOR/GENERATOR 2 (MG2) DIFFERENTIAL FRONT WHEEL ENERGY TO WHEELS IS VIA RING GEAR OF POWER SPLIT DEVICE Fig.1: the Toyota Hybrid Synergy Drive provides an “e-CVT” transmission. This allows a wide range of ratios between engine (ICE) RPM and wheel RPM without needing to change any gears. The Power Split Device (PSD) connects between the ICE, motor/generator 1 and the wheels in such a way that power to or from the wheels can be apportioned to the ICE and MG1 independently, allowing the software to control the flow of energy. MG2 rotates with the wheels as it is connected through fixed gearing. Electric Continuous Variable Transmission (e CVT), as the ratio between the engine speed and wheel speed can vary continuously and smoothly over a wide range. Differences in the engine speed and road speed can be made up for by spinning MG1 faster or slower, as the PSD creates a fixed relationship between the three speeds. Since MG2 is more highly geared in later hybrids, it provides more torque and can be used to move the vehicle at low speeds (even when the ICE is switched off). As the speed increases, MG1 can take over, as there is less gearing between it and the wheels. There is also no need for a separate starter motor to start the ICE, as it can be spun up by MG1. This allows the ICE to be switched off when stopped or moving up to about 100km/h, to save fuel and reduce pollution. It can be seamlessly stopped and siliconchip.com.au started while in motion. The ICE water cooling pump and air conditioner compressor are also powered by three-phase electric motors, rather than directly from the ICE as is the case in most vehicles. The ICE water cooling pump can be switched off to allow the ICE to get up to temperature quickly, allowing it to run more efficiently, and also throttled as needed while driving to maintain optimal engine temperature. The electric air conditioner compressor means that the ICE does not need to be cycled on and off to cool the cabin in hot weather. The inverter electronics has its own separate water cooling system to keep it cool. There is also a separate DC/ DC step-down converter to keep the auxiliary 12V DC battery (used to run the radio, lights etc) charged, which is powered from the HV battery/bus. Different operating modes are used Australia’s electronics magazine at different times, to allow the car to operate in the most efficient mode. Atkinson cycle engine The Atkinson cycle ICE is efficient and normally runs within a narrow RPM band at which it is most efficient. A typical Otto cycle engine has an average efficiency of around 20%. Toyota claims a peak thermal efficiency of 38% for its latest Atkinson engines. To achieve this, Toyota uses Variable Valve Timing intelligence (VVTi) technology to control valve timing. This is not new or unusual, as most manufacturers use similar technology, but in this case, it’s also used to implement the Atkinson cycle. This is done by delaying inlet valve closing during the compression stroke, making the compression stroke shorter than the expansion stroke. A longer expansion stroke allows the engine to capture more energy December 2019  47 ENERGY MONITOR HIGH VOLTAGE BATTERY ENERGY ENGINE ENERGY ENERGY ENERGY ENERGY ENERGY ENERGY (RUNNING) ENERGY REDUCTION GEAR SET ENERGY ENERGY ENERGY ENERGY FRONT WHEEL ENERGY MOTOR/GENERATOR 2 (MG2) ENERGY ENERGY ENERGY AXLE FRONT WHEEL DIFFERENTIAL Fig.2: this shows the flow of energy in the system when only the ICE is powering the wheels, to move the vehicle forwards. The ICE spins the PSD which in turn rotates the differential to turn the wheels directly. But the PSD also spins MG1, acting as a generator, with its electrical output routed to MG2, acting as a motor. MG2 also turns the wheels, via its reduction gear set. As the PSD ring gear speed approaches the ICE speed, more of the energy goes directly to the wheels, rather than via MG1/MG2. which would otherwise be wasted as exhaust gas heat. The shorter compression stroke is necessary to prevent fuel detonation, without needing very high octane fuel (which would be very expensive). The disadvantage of the Atkinson cycle is less overall power and poor operation over a wide range of RPM, However, as mentioned above, the PSD and MG1 are used to keep the ICE in a narrow RPM operating range, plus the electric motors provide extra power to the wheels, negating all of ENERGY MOTOR/GENERATOR 1 (MG1) AXLE AXLE SC POWER SPLIT DEVICE (PSD) (RUNNING) MOTOR/GENERATOR 1 (MG1) 20 1 9 HV BATTERY INTERNAL COMBUSTION ENGINE (ICE) ENERGY ENERGY ENERGY ENERGY ENERGY REDUCTION GEAR SET ELECTRONICS MG1 INVERTER ENERGY POWER SPLIT DEVICE (PSD) MG2 INVERTER ENERGY ENGINE WHEELS ENERGY HV BATTERY INTERNAL COMBUSTION ENGINE (ICE) MG2 INVERTER ENERGY ENERGY ELECTRONICS MG1 INVERTER ENERGY WHEELS HIGH VOLTAGE BATTERY ENERGY MONITOR SC 20 1 9 FRONT WHEEL MOTOR/GENERATOR 2 (MG2) ENERGY AXLE DIFFERENTIAL FRONT WHEEL Fig.3: at the same time as powering the wheels, the ICE can also be used to charge the HV battery. This means that the ICE can run in its most efficient regime, with the excess energy not needed for acceleration or cruising stored as electrical energy, for use later. The energy flow is much the same as in Fig.2, except that some of the extra electricity that MG1 is generating is directed into the high-voltage battery pack instead of being fed to MG2 to drive the wheels. these disadvantages. By keeping the inlet valve open at the start of the compression stroke, some of the fuel/air mixture is pushed back into the inlet manifold. This mixture will be sucked back in during the next intake stroke, so as long as the engine is designed with this in mind, it isn’t a problem. If you push the accelerator pedal to the floor, the valve timing changes to produce more power from the ICE (as well as the electric motor(s) providing some assistance, assuming the battery is not depleted). This is not as efficient as when operating in the Atkinson mode, but as hard acceleration isn’t required very often, it doesn’t have a big impact on overall efficiency. The Hybrid Camry (which, until recently, was assembled in Australia) also has underbody panels to reduce wind resistance (drag), increasing efficiency. It is classified as a ‘green car’, which in Victoria, gives discounted road registration. The Hybrid Camry does not use the Recovering potential energy When a vehicle is going up a hill at a constant speed, it requires more energy than when it is moving at that same speed on a level road. Conversely, when it is going down a hill at that same speed, less energy is required. The extra energy from the engine when going up a hill is converted into gravitational potential energy, and that same potential energy is then ‘returned’ when going down a hill, hence less energy is required to maintain speed. A vehicle’s kinetic energy (in Joules) is calculated as e(k) = m x v2 ÷ 2 where m is the vehicle’s mass in kg and v is the velocity in m/s (3.6km/h = 1m/s). Similarly, its potential energy is calculated as e(p) = m x g x h where m is again the mass in kg, g is the Earth’s gravitational constant of about 9.8m/s2 and h is the height in metres. So you can see that if the vehicle’s height (h) varies, its potential energy also changes, while kinetic energy only changes if its velocity (speed) changes. 48 Silicon Chip Hence, regenerative braking can recover energy either through deceleration (capturing excess kinetic energy) or going down a hill (capturing excess potential energy) or both. Decelerating up a hill may result in excess kinetic energy if the rate of decrease in kinetic energy is faster than the rate of increase in potential energy, or it may require energy input from the engine or motors if the reverse is true. Or it may require no energy at all if the rates are identical, ie, potential energy is being converted directly into kinetic energy. The same is true in reverse when accelerating down a hill; ie, if the rate of change in the two energies is not balanced, either energy input is required (accelerating fast), or energy may be recovered (accelerating slowly). The balance of energy is indicated on a Toyota hybrid vehicle via its “ECO” gauge. Its power needle swings up when going up a hill, indicating more energy is being used, and it swings down when going down a hill, indicating that less energy is being used. Australia’s electronics magazine siliconchip.com.au ENERGY MONITOR ENERGY MONITOR HIGH VOLTAGE BATTERY HIGH VOLTAGE BATTERY ENERGY REDUCTION GEAR SET ENERGY ENERGY ENERGY POWER SPLIT DEVICE (PSD) (RUNNING) MG2 INVERTER ENERGY REDUCTION GEAR SET INTERNAL COMBUSTION ENGINE (ICE) ENERGY ENERGY ELECTRONICS ENERGY ENERGY INTERNAL COMBUSTION ENGINE (ICE) POWER SPLIT DEVICE (PSD) HV BATTERY ENERGY ENERGY ELECTRONICS MG1 INVERTER ENERGY MG2 INVERTER ENERGY HV BATTERY ENGINE WHEELS ENERGY MG1 INVERTER ENERGY ENERGY ENGINE WHEELS ENERGY (STOPPED) MOTOR/GENERATOR 1 (MG1) ENERGY ENERGY MOTOR/GENERATOR 2 (MG2) MOTOR/GENERATOR 1 (MG1) ENERGY MOTOR/GENERATOR 2 (MG2) ENERGY ENERGY AXLE AXLE AXLE AXLE SC  20 1 9 FRONT WHEEL DIFFERENTIAL FRONT WHEEL SC 20 1 9 Fig.4: the wheels can be powered by the ICE and MG2 at the same time, providing more power and/or torque than the ICE can deliver. This compensates for the disadvantages of the more-efficient Atkinson-cycle combustion engine. As before, the ICE drives the wheels and MG1 acting as a generator, but this time the electricity from MG1 is supplemented with energy from the HV battery before being fed to MG2. So MG2 provides more energy to the wheels than MG1 absorbs from the ICE. extreme aerodynamic measures taken by the earlier Prius designs, such as enclosed rear wheels; it mostly shares FRONT WHEEL FRONT WHEEL DIFFERENTIAL Fig.5: while coasting or decelerating, or cruising down a hill, the ICE can be shut off, and the excess kinetic/potential energy of the vehicle converted into electrical energy to charge the HV battery. This is known as regenerative braking. With the ICE stopped and MG1 spinning freely, power flows from the wheels and through the reduction gear set into MG2, which operates as a generator, supplying its inverter with energy for charging the battery. its body shape with the regular Camry. However, it still achieves impressive efficiency figures, achieving an official combined rating of 4.2l/100km (2018 model), while still having 160kW of peak power available. NEXT GENERATION SMART SERIES PICK & PLACE MACHINE NeoDen S1 is the next generation of NeoDen Smart Series Pick and place machines, it offers technologically advanced, low cost solutions for low to medium volume SMT placement applications. It features fully modular design, four heads, 58 feeder slots, flying vision, auto conveyor and electronic all-in-one feeders, users can move from prototype into mass production on the same machine. Easy operation to ensure high-efficiency. Call us today: +61 2 9687 1880 Embedded Logic Solutions Pty Ltd ABN 44 109 776 098 sales<at>emlogic.com.au www.emlogic.com.au siliconchip.com.au Australia’s electronics magazine December 2019  49 ENERGY MONITOR HIGH VOLTAGE BATTERY HIGH VOLTAGE BATTERY MG1 INVERTER ENERGY ENERGY POWER SPLIT DEVICE (PSD) REDUCTION GEAR SET ENERGY ENERGY INTERNAL COMBUSTION ENGINE (ICE) ENERGY ENERGY ENERGY ENERGY REDUCTION GEAR SET ENERGY ENERGY ENERGY ENERGY ENERGY MOTOR/GENERATOR 2 (MG2) MOTOR/GENERATOR 1 (MG1) FRONT WHEEL MOTOR/GENERATOR 2 (MG2) DIFFERENTIAL Operating modes Fig.1 demonstrates that no energy is used when the car is not moving, eg, while waiting at a red traffic light. It’s a similar situation if the car is rolling down a hill, and gravitational potential energy is making the car move. Note that the Energy Monitor Display on the dashboard in Fig.1 shows no energy going to the wheels. A steep enough hill allows energy recovery via regenerative braking, as explained above. Fig.2 shows the scenario where only the ICE is powering the car in forward motion. The Energy Monitor display on the dashboard shows energy flowing from the engine to the wheels. There are two paths the energy takes to get to the wheels, after being split by the Power Split Device (PSD). The most direct path is from the PSD ring gear to the differential and then the wheels. But power also flows via MG1, MG1 Inverter, MG2 Inverter, MG2 and the reduction gear set to the wheels. AXLE ENERGY FRONT WHEEL SC FRONT WHEEL 20 1 9 Fig.6: the battery can be charged using energy from regenerative braking at the same time as using energy produced by the ICE. The ICE turns both MG1 and MG2, both acting as generators and charging the battery simultaneously. This adds to the energy being fed to MG2 from the wheels. This would typically only occur when the HV battery charge is low, and the vehicle is also slowing down, to provide the maximum amount of energy for battery charging. Some websites indicate that for some ‘gear ratios’, MG2 can operate as a generator and its output can flow to MG1, which then operates as a motor. This is the opposite of what is shown in Fig.2. However, Toyota always describes MG1 as being the generator in this case. DIFFERENTIAL FRONT WHEEL Fig.7: to minimise brake wear and heating, regenerative braking can be augmented with engine braking from the ICE. As shown here, in addition to the energy going from the wheels to MG2 to charge the battery, MG1 is also used as a generator and thus the ICE is allowed to spin. Since its fuel supply is shut off, only the energy from the wheels is available to overcome its internal friction and other losses. This provides more braking than regeneration alone, without using the disc brakes. In other words, MG1 is acting as a generator, producing electrical power which is then possibly converted to a different voltage before being fed to MG2, acting as a motor, to also provide power to the wheels. The amount of energy that flows in each path determines the effective ‘gear ratio’ of the e-CVT system. When the e-CVT is in ‘low gear’, the ICE RPM is a lot higher than the wheel RPM, causing MG1 to spin at high speed and generate more electrical energy to power MG2, and on as mechanical energy through the reduction gear set to the wheels, providing extra torque. A high electrical load on Motor Generator 1 (MG1) causes more energy from the ICE to go to the wheels via the PSD ring gear. A lighter electrical load allows more energy to go to MG1 via the sun gear. When the battery charge is below 80%, the ICE can charge the battery as well as providing forward motion. This Discrepancies in e-CVT operation description Silicon Chip ENERGY ENERGY AXLE AXLE 50 POWER SPLIT DEVICE (PSD) ENERGY AXLE SC ENERGY ELECTRONICS (ENGINE BRAKING) MOTOR/GENERATOR 1 (MG1) 20 1 9 MG2 INVERTER ENERGY HV BATTERY ENERGY ENERGY INTERNAL COMBUSTION ENGINE (ICE) (RUNNING) ENERGY ELECTRONICS HV BATTERY MG1 INVERTER ENERGY MG2 INVERTER ENERGY ENERGY ENGINE WHEELS ENGINE WHEELS WHEELS ENERGY ENERGY MONITOR situation is shown in Fig.3. This is very similar to what is shown in Fig.2, except that the electronics redirects some of MG1’s electrical output to the battery pack. Therefore, more energy must flow from the ICE to MG1 via the PSD to maintain the same wheel speed. This is indicated on the dashboard display by a second arrow, showing power also flowing from the engine to the HV battery. The ICE RPM does not necessarily need to change; the throttle simply opens further to provide more torque, supplying extra power to charge the battery. This allows the Atkinson-cycle ICE to run at a constant RPM in a narrow speed band, where it is most efficient. A similar situation occurs during forward motion if more power is required than the ICE can provide. It’s the same situation if the battery has sufficient charge and the computer decides that some of its energy should We suspect that this is a simplification on Toyota’s part. It makes sense that MG1 and MG2 may swap roles as generator and motor depending on the ratio between ICE RPM and wheel RPM, as a way to control the power split through the PSD and therefore the effective ‘gear ratio’, as determined by the percentage of energy going to the wheels which flows through the reduction gear set. Australia’s electronics magazine siliconchip.com.au ENERGY MONITOR ENERGY MONITOR HIGH VOLTAGE BATTERY ENERGY ENGINE MG2 INVERTER ENERGY ENERGY ENERGY HV BATTERY MG1 INVERTER SPINNING FREELY (CAR STOPPED) INTERNAL COMBUSTION ENGINE (ICE) ENERGY ELECTRONICS ENERGY REDUCTION GEAR SET MG2 INVERTER ENERGY HV BATTERY ELECTRONICS POWER SPLIT DEVICE (PSD) INTERNAL COMBUSTION ENGINE (ICE) (STOPPED) ENGINE WHEELS MG1 INVERTER ENERGY WHEELS HIGH VOLTAGE BATTERY POWER SPLIT DEVICE (PSD) REDUCTION GEAR SET ENERGY STOPPED ENERGY ENERGY (RUNNING) MOTOR/GENERATOR 1 (MG1) ENERGY MOTOR/GENERATOR 2 (MG2) MOTOR/GENERATOR 1 (MG1) MOTOR/GENERATOR 2 (MG2) ENERGY AXLE AXLE SC 20 1 9 FRONT WHEEL DIFFERENTIAL AXLE FRONT WHEEL Fig.8: the vehicle can move with the ICE shut off, drawing energy only from the battery (EV mode). The ICE is stopped and MG1 is allowed to spin freely. Energy from the battery is used to rotate MG2, and as this is meshed directly to the differential, despite MG1 freewheeling, it can move the vehicle. The reduction gear set provides plenty of torque for setting off or even climbing a hill. MG2’s direction of rotation determines whether the vehicle moves forwards or backwards. be used to maintain forward speed, as may be the case when driving up a hill. This is shown in Fig.4. As with Figs.2 & 3, energy is still flowing from the ICE to the wheels via the PSD and MG1/MG2. But extra power is also flowing from the battery to the MG2 inverter, so that MG2 is delivering more power to the wheels than it is receiving from MG1. By varying the position of the accelerator pedal while driving, the dashboard energy monitor display will change between those shown in Figs.2, 3 & 4. Regenerative braking Fig.5 shows what happens during regenerative braking, for example, when braking slowly to come to a stop, or when coasting or decelerating down a hill. Kinetic energy from the wheels goes through the reduction gear set to MG2, which operates as a generator to charge the HV battery. The ICE is not running, and MG1 is allowed to spin freely. To achieve maximum charging efficiency during regenerative braking, brake pedal pressure should be applied early and consistently to keep the “ECO gauge” power needle within the charging (“CHG”) range on the dial. Hard braking will engage the fricsiliconchip.com.au SC 20 1 9 FRONT WHEEL AXLE FRONT WHEEL DIFFERENTIAL Fig.9: if the HV battery is low or the ICE is cold, the vehicle can charge its battery directly from the ICE even when it is stationary. In this case, the ring gear of the PSD cannot turn, and thus MG2 can’t turn either, so all of the ICE’s energy goes into MG1 via the PSD. This is then converted to an appropriate voltage for battery charging by MG1’s inverter. tion brakes, wasting energy (although this is not a concern in emergencies!). But generally, it is better for the vehicle’s kinetic energy to be used to charge the HV battery than to generate heat energy and to wear out the brake pads. Note that while going downhill, it may be gravitational potential difference energy rather than kinetic energy that is being used to charge the HV battery (eg, when descending a hill at a constant speed). Fig.6 also shows regenerative braking, but this time, the HV battery charge is low, so the ICE is also running to recharge it. The ICE spins MG1 (acting as a generator) via the PSD, but some of its energy also passes through the reduction gear set to MG2, boosting its output as well. Additional engine braking is available when the “gear shift” lever is placed in the “B” position. This provides the situation shown in Fig.7. Note how the dashboard display (“Energy Monitor”) now shows energy flowing from the wheels to the battery but not to the engine. Regenerative braking is in effect, as shown previously. But now energy is also flowing from the wheels to the PSD, and into both MG1 (operating as a generator), and into the ICE, which has its fuel supply cut off. Australia’s electronics magazine This means that the wheels are forced to spin it, overcoming its internal friction, absorbing the excess energy. The maximum amount of energy possible is converted into electricity to charge the HV battery, with the rest being dissipated as heat in the ICE. This has the advantage, compared to using the disc brakes, that the engine has a large thermal mass along with a water-cooling system to better dissipate the resulting waste heat energy. If the HV Battery is full during regenerative braking, MG1 switches from being a generator to being a motor, so that the ICE dissipates all the excess energy. Full electric mode Fig.8 shows the car operating in electric vehicle (EV) mode. Electrical energy is taken from the HV Battery via the MG2 inverter to motor/generator 2 (MG2). This powers the wheels via the reduction gear set and differential. The ICE is not running, and MG1 spins freely as no energy is being used to charge the HV battery. When the HV battery charge is low and the car is stopped, Fig.9 shows how the ICE can still charge the battery. All of the ICE energy is sent to MG1, as the PSD ring gear cannot turn, and MG1 acts December 2019  51 ENERGY MONITOR HIGH VOLTAGE BATTERY ENGINE MG1 INVERTER ENERGY ELECTRONICS ENERGY INTERNAL COMBUSTION ENGINE (ICE) (RUNNING) MG2 INVERTER ENERGY ENERGY HV BATTERY POWER SPLIT DEVICE (PSD) ENERGY REDUCTION GEAR SET ENERGY ENERGY ENERGY MOTOR/GENERATOR 1 (MG1) ENERGY MOTOR/GENERATOR 2 (MG2) ENERGY AXLE CAR MOVING BACKWARDS AXLE SC 20 1 9 FRONT WHEEL PHASES CHANGED TO REVERSE ROTATION OF MG2 ENERGY WHEELS FRONT WHEEL DIFFERENTIAL Fig.10: here is how the vehicle is reversed even when the HV battery charge is too low to power MG2. This is effectively a combination of the configurations shown in Fig.8 & Fig.9, with the ICE charging the HV battery via MG1 and then the HV battery supplying the power to run MG2. This is necessary as only MG2 can move the vehicle in reverse. as a generator to charge the HV Battery. This mode often occurs after the car is first started, as it allows the ICE to quickly get up to operating temperature without wasting any energy (as long as the battery is not full). Reversing When the vehicle is reversing using electrical energy from the HV battery, the situation is the same as shown in Fig.8. The only difference is that MG2 ro- tates in the reverse direction as the drive sequencing of its three coils changes. But if the battery is low, the car still needs to be able to reverse, and this can be achieved as shown in Fig.10. This is effectively a combination of Fig.8 (EV mode) and Fig.9 (stationary battery charging). The ICE is switched on to charge the HV battery via MG1, operating as a generator, and the resulting electrical energy is also used to power MG2 for moving the vehicle. As shown, a small amount of the energy going to MG2 is also fed back to MG1 via the PSD, and that energy is recovered as electricity. As before, MG2’s direction of rotation is reversed by manipulating the sequencing of its phases. Note that the Energy Monitor display does not show energy flowing from the engine to the wheels or from the HV battery to the wheels in this case, although that is surely the case. But this is an unusual situation. In most circumstances, there will be enough energy in the battery to reverse, unless the car has been sitting for a long time. SC WOW! A GIFT SUB FOR CHRISTMAS! Not that type of sub . . . The perfect present for someone special in your life is a gift subscription to their favourite magazine – Australia’s own SILICON CHIP. Every month, direct to their mailbox. No more queueing at the newsagents. No danger of missing out because they’ve sold out! No more forgetting to pick up the current issue! And they’ll be reminded of your thoughtful gift month after month after month – every time they open their copy of SILICON CHIP. 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Subscription prices (all prices AU$): 6 months (Aust) 6 months (NZ) Printed Edition (inc postage) $57.00 $61.00 Online Edition (anywhere – from siliconchip.com.au) $45.00 Both (Printed AND Online Editions) $69.00 $73.00 12 months (Aust) 12 months (NZ) $105.00 $109.00 $85.00 $125.00 $129.00 24 months (Aust) 24 months (NZ) $202.00 $215.00 $164.00 $240.00 $253.00 Here’s how to order your gift subscription . . . (hurry - there’s only a couple of weeks until Christmas!) ONLINE: Go to siliconchip.com.au/Shop/GiftSubs – and ll in the details! By email: Send all details - your name, credit card no, subscription length and recipient’s details to silicon<at>siliconchip.com.au By mail: Ditto - send all those details to Silicon Chip, PO Box 139, Collaroy, NSW 2097. 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Comes in two parts: Codey (detachable mainboard) equipped with more than 10 electronics modules that can be controlled via code. Rocky (car) that lets you take Codey anywhere you want. Support AI and IoT. Cloud storage. Ages 6+. KR9230 WAS $149 Learn about science and solar. Easy snap together construction. Ages 8+. KJ9026 WAS $24.95 FROM SAVE $30 3-IN-1 DRONE, TANK & CAR Whether you want to fly, drive or jump, simply SAVE $50 SOLAR ROVER KIT new 49 $ NOW 19 $ 95 EA SAVE $5 CARDBOARD RADIO CONSTRUCTION KIT Make your own AM/ FM radio. No soldering needed. Requires 3 x AA batteries (SB2425 $2.95 sold separately). Ages 8+. KJ9021 WAS $24.95 NOW 2995 $ 14 $ ROBOT ARM KIT AIR POWER ENGINE CAR KIT Build six different projects: windmill, car, dog, plane, airboat, & revolving plane. Power from the sun or household 50W halogen light. Ages 10+. KJ8926 7 95 $ SAVE $3 95 SAVE $5 PLANETARIUM EDUCATIONAL KIT POTATO CLOCK Build your own planetarium model. Paint it and add highlights and create a glow effect. Snap to build, no glue required. Age 8+. KJ8994 WAS $9.95 54 Operates entirely using air and travels up to 80m on one single tank. No batteries or motor required. Ages 10+. KJ8967 WAS $49.95 NOW 6 $ SAVE $15 95 6-IN-1 EDUCATIONAL SOLAR KIT NOW click & collect NOW 5495 $ SAVE $20 JUST NOW 99 $ Run a digital clock in potatoes, lemons, apples! Safe and highly educational. Ages 10+. KJ8937 WAS $12.95 Buy online & collect in store Capable of 5 separate movements and can easily perform complex tasks. Excellent project for anyone interested in robotic construction. 100g lift capacity. Ages 12+. KJ8916 WAS $69.95 ALSO AVAILABLE: USB Interface Kit KJ8917 WAS $49.95 NOW $39.95 SAVE $10 NOW 995 $ SAVE $6 QUARTZ CLOCK MOVEMENT Make or repair a clock. Very reliable. Self starting one second stepping motor. Supplied with three sets of hands. XC0100 WAS $15.95 AS LOW AS 21C PER BATTERY! 24 PACK! 495 $ EA DON'T FORGET THE BATTERIES! 24pk Zinc carbon batteries. Fantastic value for money. AAA SB2550 AA SB2552 ON SALE 24.11.19 - 26.12.19 YOUR DESTINATION FOR: HOME MAINTENANCE NOW 109 $ INSPECTION CAMERA Great for inspecting hard to reach areas or locating objects in tight spaces. 2.4” LCD. LED illuminated. QC8710 WAS $149 ALSO AVAILABLE: 2m Gooseneck Extension QC8702 WAS $79.95 NOW $59.95 SAVE $20 NOW 99 Holiday To-Do's $ SAVE $30 YOUR DESTINATION FOR: SAVE $40 HOLIDAY TO-DO'S AUTORANGING MULTIMETER Measure AC/DC voltage (600V) and current (10A). Includes case and temperature probe. QM1323 ONLY 4995 $ See website for details. GAS SOLDERING TOOL KIT Quality Super Pro iron. Includes tips and cleaning sponge/tray. Storage case included. TS1318 WAS $129 PREPARE THE CAR FOR THE ROAD TRIP 2 FOR NOW 90 9995 $ $10 125A DUAL BATTERY ISOLATOR KIT Automatically combines two batteries when charging and isolates the two when not. Suitable for 12V systems. MB3681 5" LED VEHICLE FLOODLIGHT NOW ONLY 29 $ 12EA 95 $ SAVE $10 A range of ultra-bright LED replacement "festoon" globes for car interior lights. Compatible with modern "CANBus" systems. ZD0750/52/54 RELAY WIRING KIT The kit includes a 2m wiring loom, 30A relay, a contura style switch, and one high current output. SY4081 WAS $39.95 NOW 995 Add some colour to your water feature, fish tank, vase etc. 12 different colours and 3 different light patterns. IP65 rated with a max depth of 2m. SL3933 WAS $19.95 Run your outdoor water feature, aquarium, or garden pond without the need for wiring. Comes with its own solar panel, cable and pump. 0.9W ZM9200 $49.95 2.4W ZM9202 $79.95 19 $ P3 6 443 MP3 Mobile device charging solution for home and travel. IN-CAR: MAINS: 3A Single MP3680 $19.95 3A Single MP3443 $29.95 5.4A Dual MP3682 $29.95 3A Dual MP3437 $39.95 More ways to pay: 95 SAVE UP TO $20 M ULTRA FAST USB CHARGERS Simple and accurate device for checking pH levels in water. 1 x 9V battery & buffer solution included. QM1670 WAS $64.95 Buffer Solution to suit QM1670 QM1671 $8.95 NOW FROM 82 19 95 HAND HELD PH METER SOLAR POWERED WATER PUMPS UP TO 4X FASTER THAN STANDARD CHARGING 50M 1080P HDMI EXTENDER BACK Extends HDMI connections over a single Cat5e/6 cable. Ideal for running HDMI signals to new locations or connecting through existing building cables. IR extender. AC1783 WAS $129 WEATHERPROOF NOW FROM 39 $ 95 SAVE UP TO $20 RECHARGEABLE LED WORK LIGHTS Rugged addition to your equipment. Features multiple light modes, USB port & battery level indicator. 10W 1000 Lumen SL2858 WAS $49.95 NOW $39.95 SAVE $10 20W 1800 Lumen SL2859 WAS $99.95 NOW $79.95 SAVE $20 SAVE $5 4995 RGB UNDERWATER LIGHT $ 5995 $ $ HALF PRICE! FROM NOW FROM $ 95 REPLACEMENTS GLOBES IMPROVE THE POND OR POOL FRONT SAVE $40 ONLY SAVE Compact but powerful, producing over 1000 lumen of bright light. IP68 rated. 12/24V system. Stainless steel mounting hardware. SL3931 RRP $29.95ea. 89 $ 49 $ UPDATE THE MANCAVE USB TYPE-C MAINS POWER ADAPTORS Suitable for charging the latest Type-C phones and tablets. 18W MP3410 WAS $29.95 SAFER, HIGHER POWER NOW $19.95 SAVE $10 45W MP3412 WAS $59.95 UP TO 70% FASTER THAN STANDARD CHARGING NOW $39.95 SAVE $20 5 USB PORTS JUST 5995 $ 5 PORT CHARGING STATION Charge up to 5 USB devices at the same time! Boasts a powerful 2.4A per port. Includes 6 dividers and power supply. WC7766 JUST 29 $ • NO MESSY CABLE • SUPPORTS FAST (10W ) & STANDARD (5W) CHARGING 95 new FAST WIRELESS QI CHARGER & MOUSE PAD Wirelessly charge your QI-enabled phone while you're using your computer. Non-slip rubber base. Supplied with a USB power cable. XM5098 Available early December. Phone not included. 55 RETRO NES CASE Includes access to all ports on your Raspberry Pi 3B+ and a handy storage slot for your spare memory cards. Just add a Raspberry Pi 3B+ and power supply for set-up, download games from web and start gaming! XC4403 RRP $39.95 YOUR DESTINATION FOR: MAKER RETRO NES STYLE CONTROLLER SNES layout. Features A/B/X/Y buttons, start, select, and direction controls. XC4404 RRP $9.95 ea. RETRO GAMING BUNDLE 4995 $ PROJECTS SAVE $990 VALUED AT $59.85 Includes XC4403 + 2 × XC4404 NOW 1295 FREE Suits 25mm mounting hole. Microswitch for reliable operation. Red, yellow, green, blue & white colours available. SP0662-SP0669 RRP $9.95 ea. 9 ber cem De arly WITH PURCHASE OF THIS LED CUBE KIT! (XC4625 valued at $14.95) Ava i lab le E Suitable for any game that works with a USB joystick. XC9046 WAS $19.95 1/2 PRICE ENCLOSURE 99 $ A GREAT WAY TO GET INTO THE CHRISTMAS SPIRIT SAVE 30% JUST 2995 $ KIT VALUED AT: $146.17 BUILD YOUR OWN: CHRISTMAS WI-FI ROVER Control our 4WD metal chassis car kit (KR3166) with Wi-Fi TREE via the MEGA board with Wi-Fi (XC4421). Simple 2-board Learn about electronics, soldering, and Arduino® all at the same time. This kit includes a tree shaped circuit board, coloured LEDs, and electronic components to produce amazing lighting effects when combined with an Arduino® UNO (XC4410 $29.95 sold separately). • 90(H) x 50(W) x 12(D)mm (including Pins) XC3754 USB INTERFACE FOR JOYSTICK AND BUTTONS 2 way, 4 way and 8 way options restrictor plate, metal mounting plate and main shaft, removable knob. SM1052 WAS $19.95 CONTROL USING YOUR SMARTPHONE 95 SAVE $5 ARCADE JOYSTICK WITH MICROSWITCHES BUNDLE DEAL BUILD YOUR OWN: $ SAVE $7 ILLUMINATED ARCADE BUTTONS $ 1495 $ BUY 1 GET 1 ONLY NOW connection with motor shield, use this as a basis for your future robotic projects. Comes with mounting hardware. Requires 8 x AA batteries. FOR PARTS LIST AND STEP-BY-STEP INSTRUCTIONS VISIT: www.jaycar.com.au/wifi-rover RGB LED CUBE KIT WITHOUT DRIVER Stunning piece of art-meets-illumination that you can build yourself. 64 individually addressable RGB LEDs arranged as a 4x4x4 matrix. XC4624 Limited Stock. DON'T FORGET THESE MAKER ESSENTIALS NOW JUST 89 $ 95 $1995 SAVE $10 48W SOLDERING STATION Adjustable temperature (150-450°C), ceramic element and a lightweight pencil for fatigue-free soldering. Mains powered. TS1564 WAS $99.95 56 click & collect DUST REMOVER 250G Non flammable gas which allows removal of dust from electronic, electrical and optical devices. NA1018 Buy online & collect in store JUST 1295 $ HAND-HELD MAGNIFYING GLASS Powerful 3x magnification. ChipOn-Board LEDs. Lightweight. On/off switch. QM3535 NOW 950 $ SAVE $4 BREADBOARD JUMPER KIT Kit includes 70 stripped pieces of single core sturdy wire. 5pc x 14 different lengths. PB8850 WAS $13.50 ON SALE 24.11.19 - 26.12.19 YOUR DESTINATION FOR: Maker Kits & Bundles BUNDLE DEAL 3295 $ DO MORE WITH YOUR: micro:bit SAVE 40% SENSOR SHIELD VALUED AT: $58.85 Enables you to connect multiple sensor modules to your micro:bit board. XC4336 RRP $14.95 INCLUDES 1 x XC4336, XC4330 & XC4332 PROTOTYPE BOARD WITH 400 PIN BREAKOUT BOARD BREAKOUT BOARD WITH 2 X AA BATTERY HOLDER Designed to break out all of the IO pins on your micro:bit for you to create additional circuits and hardware. Supplied with 400-hole breadboard. XC4332 RRP $23.95 Provides an independent 3V power supply to your micro:bit project and enables you to interface to other hardware. 170mm long power lead included. XC4330 RRP $19.95 MAKE YOUR PROJECTS: VALUED AT: $50.85 INCLUDES 1 x XC4514, XC4630 & XC4416 NOW MEGA PROTOTYPE SHIELD WITH BREADBOARD Large, colourful touch display shield which piggy-backs straight onto your UNO or MEGA. Fast parallel interface.microSD card slot. Resistive touch interface. XC4630 RRP $29.95 Gives you plenty of room to prototype your latest MEGA project. The stackable shield provides access to all of the MEGA pins and plenty of solder pads to prototype on. XC4416 RRP $12.95 EXPAND ON YOUR: SAVE 20% VALUED AT: $62.85 INCLUDES 1 x MP3536, XC9030 & XC9006 OFFICIAL RASPBERRY PI 3B CASE 16GB MICROSD CARD WITH NOOBS Comes pre-loaded with noobs software for easy install of raspbian operating system. Includes adaptor. XC9030 RRP $24.95 Snap-together case with numerous removable panels. Stylish red and white design. Easy no-tools assembly. Four Rubber feet included. XC9006 RRP $14.95 JUST 450 $ In the Trade? Contains a Arduino-compatible MEGA main board, a breadboard, jumper wires and a plethora of peripherals in a plastic organiser. See website for details. XC4286 WAS $109 4995 Use with Raspberry Pi, charge power banks, portable speakers etc. Can also be used for other USB powered devices with a Micro USB connector. 5.1V 2.5A. MP3536 RRP $22.95 10 Leads supplied, 2 of each colour. STANDARD WC6010 $6.95 HEAVY DUTY WC6020 $11.95 SAVE $10 MEGA EXPERIMENTERS KIT $ POWER SUPPLY FOR RASPBERRY PI JUMPER LEADS 99 $ BUNDLE DEAL Raspberry Pi WC6010 An excellent introduction to electronic construction and coding, ideal gift for a young maker! No soldering or prior programming knowledge is required. Kit includes micro:Bit board & common electronics components such as resistors and servo motor, and all the necessary prototyping accessories plus 36-page instruction guide. XC4322 SAVE 20% 240 X 320 LCD TOUCHSCREEN 6 MICRO:BIT CREATOR KIT 3995 Use it to run your 5V Duinotech projects from a 6V, 9V or even 12V supply. Accepts any voltage from 4.5-35VDC, and outputs any higher voltage from 3-34VDC. XC4514 RRP $7.95 95 9995 $ $ DC VOLTAGE REGULATOR FROM JUST BUNDLE DEAL MEGA $ INCLUDES MICRO:BIT BOARD ARDUINO® STACKABLE HEADER Build a stackable shield, or make your current shield stackable. Includes: 1 × 10-pin, 2 × 8-pin, 1 x 6-pin, 1 x 2x3-pin (for ICSP). HM3208 JUST NOW 69 $ SAVE $30 37-IN-1 SENSOR KIT Includes commonly used sensors and modules for Duinotech and Arduino®: joystick, magnetic, temperature, IR, LED and more. Packaged in a clear plastic organiser. XC4288 WAS $99 See website for details. 9 $ 95 BREADBOARD POWER MODULE Adds a compact power supply to your breadboard. Power from a USB socket or DC. 3.3V or 5V switchable. XC4606 NOW 1995 $ SAVE $10 100-PCS LED PACK Contains 3mm and 5mm LEDs of mixed colours. Even includes 10 x 5mm mounting hardware FREE! Mix of red, green, yellow, orange LEDs. See website for full contents. ZD1694 WAS $29.95 57 YOUR DESTINATION FOR THE BEST REWARDS & PERKS: Love jaycar? You’re going to love our rewards! Shop In store & online Earn Points For dollars spent Get Rewards eCoupons for future shops in store 1 point = $1 200 points = $10 eCoupon + Perks Offers, event invitations, account profile and more... 79 44 $ $ SAVE OVER $40 SAVE 25% GAMER'S BUNDLE Designed for hardcore gamers who enjoy many hours of gameplay. Includes: Keyboard & mouse, mouse pad & headphones. See T&Cs for details. Valued at $119.85 CLUB OFFER 1590 $ CLUB OFFER CLUB OFFER 95 HALF PRICE! FLEXIBLE EL WIRE LIGHTING Add colourful lighting to your Christmas decorations, party, costume, signage etc. Includes 2 x EL wire light, controller & splitter. NON-CONTACT THERMOMETER Measure temperature in hard to reach places, hot or hazardous areas. QM7215 REG $59.95 See T&Cs for details. Valued at $32.80 CLUB OFFER SAVE CLUB OFFER SAVE CLUB OFFER SAVE CLUB OFFER SAVE DESKTOP POWER SUPPLY 30M POLY WRAPPED CAT 5E NETWORK CABLE DIGITAL MULTIMETER KIT 10X LED MAGNIFIER WITH SCALE 15% 35% High current 120W 12VDC 10A. MP3241 REG $84.95 CLUB $69.95 4x24 AWG Solid Core twisted pairs. WB2023 REG $39.95 CLUB $24.95 CLUB OFFER SAVE CLUB OFFER SAVE U16 FERRITE NOISE SUPPRESSORS HEAVY DUTY TERMINAL CRIMPER CLUB OFFER SAVE 25M GAFFER TAPE 50% 20% Typical impedance at 25MHz 300Ω approx. Built in rotating die. Hex crimper. 450mm Pk 4. LF1292 REG $12.95 CLUB $6.45 long. TH1849 REG $49.95 CLUB 39.95 20% Includes DMM case, LCD, solder, battery, test leads, PCB, manual and electronic components. KG9250 REG $24.95 CLUB $19.95 CLUB OFFER SAVE 10x magnification. 180mm long. QM3539 REG $29.95 CLUB $22.95 CLUB OFFER SAVE 30% 40% IP65 SEALED ABS ENCLOSURE SPEAKER GRILLE CLOTH High quality. Black. 1.5 x 1m. CF2752 REG $17.50 CLUB $10.50 CLUB OFFER SAVE CLUB OFFER SAVE CLUB OFFER SAVE METER LED LIGHTING MODULE STRING HAND CRANK DYNAMO Suitable use for wood & building materials. QP2310 REG $34.95 CLUB $27.95 20% 25% Flexible & weatherproof. 12VDC. Pre-assembled. Made from plastic Cool white or Blue colour available. to easily re-work to fit your projects. ZD0590-ZD0593 REG $16.95 CLUB $12.95 MD7000 REG $19.95 CLUB $14.95 20% OFF EXCLUSIVE CLUB OFFER Your Club. Your Perks! 3D PRINTER FILAMENT* Keep up to date with the latest offers and what’s on! visit www.jaycar.com.au/makerhub *Applies to All types. 1.75mm & 3.00mm. 58 20% 222(W) x 146(D) x 75(H)mm. Dark grey. HB6132 REG $28.95 CLUB $19.95 % 20 POCKET MOISTURE Waterproof. Low sheen. 48mm wide. NM2810 REG $14.95 CLUB $11.95 20% click & collect Buy online & collect in store ON SALE 24.11.19 - 26.12.19 YOUR DESTINATION FOR: Workbench Essentials JUST 5 $ WORKBENCH BUNDLE PACK 95 Package includes the essentials you need to do any repair work without straining your eyes. ENGINEERS RULER - 25CM WITH SCALE Includes several charts and diagrams i.e angle gauges, IC pin spacing tables and chip resistor/capacitor package sizes. R-4 gold plated. TH2520 KIT INCLUDES: JUST 2495 $ new 48 PIECE SCREWDRIVER SET Made from S2 tool steel. Suitable for electronics gadget repairs. Includes carry case. TD2134 JUST 19 $ 95 1. Illuminated Gooseneck Magnifier QM3532 $29.95 2. Desktop PCB Holder TH1980 $19.95 3. Benchtop Work Mat HM8100 $12.95 4. Electronic Cleaning Solvent 175g NA1004 $11.50 SAVE 35 Control print jobs via the cloud using FlashCloud and/or Polar Cloud. Small but compact structure with no angular design. Ready to use and no levelling printing. Removable, heatable and bendable plate. Built-in camera function. Prints up to 150(L) x 150(W) x 150(H)mm. TL4256 Bonus $100 Gift Card JUST 899 $ GIFTS FOR MODEL MAKERS 1299 DUAL FILAMENT 3D PRINTER CR-X Allows you to combine colours and materials creating high-quality prints. 300 × 300 × 400mm print area. Oversized bed screws for leveling the print bed. Dual cooling fans. SD memory card slot. TL4410 19 SAVE $5 MICRO ENGRAVER Engraves glass, ceramics, metals and plastics for security or insurance. Spins at 10,000 RPM. Batteries and case included. TD2468 WAS $24.95 4 95 ARTWORK KNIFE Light duty with safety cap. Ideal for fine angle cuts, etching, hollowing, scoring, scraping, scribing, stripping and trimming. HG9955 More ways to pay: 95 14 ROTARY $ TOOL BIT SET 192 piece. Comes with a variety of components for sanding, engraving, cutting, grinding, and polishing. TD2455 See website for inclusion. NOW 1195 $ SAVE $3 NEEDLE FILE KIT 10 piece. All have integrated plastic handles and come in a handy storage wallet. 162mm long each. TD2128 WAS $14.95 • DUAL COLOUR PRINTING • 4.3" COLOUR TOUCH SCREEN • SILICON PRINTING PLATFORM • LARGE POWER SUPPLY CUT, STRIP & CRIMP NOW JUST JUST $ • 2.8" TOUCHSCREEN PANEL • WI-FI, USB & ETHERNET CONNECT • LOW NOISE OPERATION • AUTOMATIC FILAMENT FEEDING 95 2 % VALUED AT: $74.35 ADVENTURER 3 3D PRINTER $ 3 4495 Bonus $50 Gift Card JUST 4 BUNDLE DEAL 12 drawer system to get your work space tidied up and in order. Modular slide locking system allows stacking vertically and horizontally. Clear plastic drawers. HB6332 $ 1 $ new MODULAR STORAGE CABINET NOW THE PERFECT GIFT FOR ELECTRONICS ENTHUSIASTS & HOBBYIST 6 $ 95 SAVE $2 JUST 1295 CARBON STEEL $ CAT-5 PUNCH-DOWN TOOL 127MM PRECISION SIDE CUTTERS JUST JUST Strip wire up to 5-6mm, and doubles as a punch-down tool for 110/88-type terminals with blade. TH1738 WAS $8.95 16 $ 95 WIRE STRIPPER Strip all sorts of cable without damaging the conductors. One hand operation. TH1824 Colour may vary Easily cut leads ideal for fine PCB work. Soft padded handles. Carbon steel. TH1897 1495 $ CRIMPING TOOL Handles non-insulated lugs from 14-18 AWG and 22-26 AWG. Built-in wire cutter. Comfortable handles and spring-loaded. TH1834 59 NEW RANGE HIGH POWER PLUGPACKS These slim mains power adaptors are lightweight and don’t block other appliances connected to your powerpoint or powerboard. What's NEW for Christmas FROM 95 SWITCHMODE MAINS ADAPTORS WITH 7 CHANGEABLE PLUGS 12VDC 4A 48W 12VDC 5A 65W 24VDC 2.5A 65W 48VDC 1.25A 65W MP3550 $39.95 MP3560 $49.95 MP3562 $49.95 MP3564 $49.95 JUST 5995 $ 65W UNIVERSAL LAPTOP POWER SUPPLY • DUAL BAND TECHNOLOGY • 5 X GIGABIT PORTS • CONNECT MULTIPLE DEVICES JUST 169 $ AC2100 SMART WI-FI ROUTER JUST 8 PLUGS TO WITH USB SOCKET SUIT POPULAR Spare or replacement power supply for LAPTOPS your laptop, notebook, or ultrabook. MP3342 9995 $ AC1200 HIGH POWER DUAL BAND WI-FI EXTENDER Incredibly fast Wi-Fi speeds up to 2100Mbps for strong, steady signal throughout your home so you can enjoy exceptionally smooth, responsive gaming and uninterrupted streaming. 6 antennas to help boost signal strength and reduce dead-spots. YN8394 25 YEAR WARRANTY • REPLACE YOUR OLD "BRICK" STYLE POWER SUPPLIES 39 $ • Switchmode design • Low energy consumption • Regulated output voltage Quickly eliminate dead-spots and enhance your Wi-Fi signal or provide an access point on your existing wired network. Plugs straight into mains power point. Supports wireless speed of up to 1200Mbps. YN8374 Due early December. FROM 199 ONLY $ 89 $ FOLDING SOLAR PANELS with Charge Controllers Convenient and portable power solution for camping and outdoor power applications. Higher power output compared to older models of the same size. Supplied with 10W PWM charge controller with USB port, 5m extension lead with Anderson connectors and heavy duty bag for portability. 110W ZM9175 $199 130W ZM9177 $239 MORE EFFICIENT COMPARED TO OLDER MONOCRYSTALLINE DESIGNS 95 • NO MESSY CABLE FAST WIRELESS QI CHARGER, CLOCK, RADIO & SPEAKER Keep track of the time and wirelessly charge your compatible Smartphone. AR1936 Available early December. FROM 99 $ 95 DC9064 TRANSPARENT ON-GLASS UHF ANTENNAS With easy installation, these new antennas offer superior performance compared to the current on-glass antennas & are ideal for those in need of a discrete UHF antenna set-up. Mounted to the inside of the windshield to mitigate against theft, vandalism or wind noise. 2DBI DC9062 $99.95 4DBI DC9064 $139 (Shown) TERMS AND CONDITIONS: REWARDS / NERD PERKS CARD HOLDERS FREE GIFT, % SAVING DEALS, DOUBLE POINTS & 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: BONUS: $100 Giftcard applies for purchases of TL4400. Club Offer: Micro:Bit Christmas Tree Project includes 1 x XC4320 + 1 x XC4330 + 3 x ZD0185 + 3 x ZD0160 + 1 x WC6026 + 2 x ZD0170 for $49.95. Club Offer: Arduino Controlled Christmas Lights includes 1 each of ZK8880, XC4410, ZV1656, LF1276, ZR1020, XC4482, RE6310, RE6336, RT4652, RR0580, RZ6624 & PI6502. Page 3: Multibuys: 2 x SL3931 for $49.90. page 4: Retro Gaming Bundle includes 1 x XC4403 + 2 x XC4404 for $49.95. Wi-Fi Rover Bundle includes 1 each of KR3166, XC4421, XC4472, HP0418, HP0425, HP0148 & PH9200, 6 x RC5360 for $99. Page 4: Multibuys: Buy 1 Get 1 FREE applies to SP0662, SP0664-0666, SP0669 or combination. Page 5: Micro:Bit Bundle includes 1 each of XC4336, XC4330 & XC4332 for $32.95. Arduino Mega: 1 each of XC4514, XC4630 & XC4416 for $39.95. Raspberry Pi: 1 each of MP3536, XC9030 & XC9006 for $49.95. Page 6: Club Offer: Gamer’s Bundle includes 1 each of AA2126, XM5096 & XC5132 for $79. Club Offer: Flexible EL Wire Lighting Bundle includes 2 x EL Wire of your choice (SL2442-SL2448, 1 x SL2440 & 1 x SL2443. Club Offer: 20% OFF 3D Printer Filament applies to all types i.e ABS, PLA, PET etc. 1.75mm & 3.00mm dia. All colours & sizes. Page 7: Workbench Bundle pack includes 1 each of QM3532, TH1980, HM8100 & NA1004. Page 7: BONUS: $100 Giftcard applies for purchases of TL4410. $50 Giftcard applies for purchases of TL4256. For your nearest store & opening hours: 1800 022 888 www.jaycar.com.au Over 100 stores & 130 resellers nationwide NEW STORE Tamworth Shop 1/454-456 Peel St, Tamworth, NSW PH: (02) 6702 0197 HEAD OFFICE 320 Victoria Road, Rydalmere NSW 2116 Ph: (02) 8832 3100 Fax: (02) 8832 3169 ONLINE ORDERS www.jaycar.com.au techstore<at>jaycar.com.au Arrival dates of new products in this flyer were confirmed at the time of print but delays sometimes occur. Please ring your local store to check stock details. Occasionally there are discontinued items advertised on a special / lower price in this promotional flyer that has limited to nil stock in certain stores, including Jaycar Authorised Resellers. These stores may not have stock of these items and can not order or transfer stock. Savings off Original RRP. Prices and special offers are valid from catalogue sale 24.11.19 - 26.12.19. In this second and final article on the new Superhet Stereo FM Radio, we explain how to assemble and align it for best performance. You can then put it into its superb acrylic case, and your friends won’t believe that you built it! Part 2 By John Clarke The Super-9 Stereo FM Radio Receiver A ssembling the Super-9 Stereo FM Radio is not difficult; everything is mounted on one large PCB. And the alignment is a snap using the small oscillator we’ve designed and some other basic equipment, as we will explain shortly. Construction The Radio is built on one doublesided PCB coded 06109181 which measures 313 x 142.5mm. It is housed in a multi-piece laser-cut acrylic case, available from the SILICON CHIP ONLINE SHOP. This also includes a transparent siliconchip.com.au tuning dial. Station call signs (eg, JJJ for triple J) and frequency markings that are screen printed on the main PCB can be seen through it. Use the PCB overlay diagram, Fig.8, as a guide as you build the Radio. Begin construction with the surfacemounting parts. These are not difficult to solder in using a fine-tipped soldering iron. You need good light and might need a magnifying lens or glasses to see well enough. These parts are Q1-Q4, VC1-VC3, XF1 and IC2, IC5 and IC6. You need to pay particular attenAustralia’s electronics magazine tion to ensure that Q1, Q2, VC3, XF1 and the ICs are fitted with the correct orientation. Mosfets Q1 and Q2 have a larger pad for the source connection, which is marked with an “S” in Fig.8 and on the PCB itself. VC3 has a stripe on the package that indicates the cathode, marked as “k” on the PCB. XF1 has a dot in the corner to indicate pin 1, which lines up with the “1” printed on the PCB. Similarly, the SMD ICs have a dot or divot to indicate pin 1, or you can look for the bevelled edge on that side of the chip package. While the polarity of the other SMDs December 2019  61 also matters, the remaining surfacemount parts have one pin on one side and two on the other, so the correct orientation is obvious as long as you don’t have the parts upside-down (their leads should be touching the surface of the PCB before soldering). Mosfet Q4 is mounted on the opposite side of the PCB from most of the other components; LED1 and LED2 are also mounted on the back (see Fig.9). Everything else is installed on the top side. It’s best to fit Q4 after the other SMDs since it will prevent the board from sitting flat on its back once it is in place. Make sure the NE592 is used for IC2 and LM4865s for IC5 and IC6. These could get mixed up as they are all in the same SOIC-8 style package. For each device, solder one pad first and check its alignment. Re-adjust the component positioning by reheating the solder joint if necessary before soldering the remaining pins. If you accidentally bridge two or more pins, add a little flux paste to the 62 Silicon Chip bridge and then clean it up by applying some solder wick with heat from your soldering iron. Through-hole parts Continue construction by installing the fixed-value resistors. You can use the colour code table from last month, as a guide to figure out which is which. But it’s best to check each set with a multimeter before soldering them in place, as the colour codes are easy to misread. Some colour bands can appear similar to others depending on lighting where red, brown and orange can appear the same. The resistors are not polarised, so they can be inserted either way into the board. Ferrite beads FB1 and FB2 can then be installed by feeding resistor lead off-cuts through the beads and then fitting them in the locations shown in Fig.8. Now is also a good time to fit zener diode ZD1. It must be soldered with its cathode stripe facing towards the top Australia’s electronics magazine of the board, as shown. Follow with axial RF inductor L5, which looks like a fat resistor. It is not polarised. Next, fit through-hole ICs IC1, IC3 and IC4. As with the SMD ICs, check carefully that their pin 1 is orientated correctly as per Fig.8 and that they have been pushed down fully onto the board before soldering the leads. Don’t use sockets as they could prevent the Radio from working correctly. Now mount trimpots VR2-VR5 and VR7. These often are marked with a code. The corresponding codes for these trimpots were shown in the parts list last month. Multiturn trimpots VR3 and VR4 must be orientated with the adjusting screw positioned as shown on the overlay diagram. This is so the adjustment direction will be correct. Fit the 18 PC stakes now. There are two for the antenna and its associated GND point, three to mount the two shields on either side of Q1/VC1, four for pot VR6 (one to ground its body), two above CON3 (TP5V/GND), two siliconchip.com.au Winding the Coils 5 10 This samesize photo of the completed PCB shows all components mounted on the top side. There are three extra (small) PCBs required – the whip antenna support and the two vertical RF shields (all top left corner). 9 L1-L3: 5 turns on 5mm mandrel 0.8mm EnCu wire 5 L4: 0.5 turn on 5mm mandrel 0.8mm EnCu wire 1-2 3-4 T1 Between pins 1-2: 25 turns Between pins 3-4: 5 turns Both 0.125mm EnCu wire near Q3/VC2 in the lower-left corner, and five in the middle of the board, to the left of the battery holder and REG1. Note that while the left-hand shield is held in place with two PC stakes, the right-hand shield only uses one at the top, and is soldered directly to the board ground plane at the bottom. If you haven’t fitted LED1 or LED2 yet, on the underside of the board, now is a good time to do so. Next, install the capacitors. There are three types used in the circuit. The non-polarised MKT polyester types can be recognised by their rectangular prism shape. The ceramic capacitors are also not polarised. Generally, small capacitors are not marked with their actual value and have a code instead. These codes are listed in the parts list last month. The third type of capacitor used in this project is the electrolytics. These are marked with their value in µF and are polarised, so they must be inserted the right way around. The negative lead is marked with a siliconchip.com.au stripe on the capacitor body, while the positive lead is the longer of the two. This goes into the pad marked with a “+” on the PCB. The 2N7000 Mosfets (Q5 and Q6) can go in next. Crank out their leads to match the mounting pad spacing using small pliers. Q7 (the SUP53P06-20) is in a larger package which is mounted flat onto the PCB and secured with an M3 x 6mm screw and nut. Bend the leads to insert into the PCB holes with the flat side down, then secure the tab against the PCB with the screw and nut. You can then solder Q7’s leads and trim them. REG1 is a 7805 three-terminal regulator in a similar package and is mounted in the same way as Q7, except that a small heatsink is sandwiched between it and the PCB. The two shields can be fitted now. They are small PCBs, as shown in Fig.7. These are placed vertically and then soldered to the three PC stakes. Then attach the lower section of the right-hand shield directly to the Australia’s electronics magazine 1-2 L6: Between pins 1-2: 23 turns of 0.125mm EnCu wire 1 5 4 2 3 Base diagram top view SC 20 1 9 ALL DIMENSIONS IN MILLIMETRES EnCu = enamelled copper Fig.5: here’s how to wind the coils and transformer for the Radio. L1-L4 are air cores wound using 0.8mm diameter enamelled copper wire on a 5mm mandrel (a cylindrical former), which is then removed. L6 and T1 are wound using 0.125mm diameter enamelled copper wire on plastic formers, with the ends of the wire soldered to the former pins as shown. L5 is not depicted as it is a pre-fabricated RF choke. December 2019  63 Then trim their leads so that they protrude through the board by about 2mm. L4 is placed against L3. Note that the enamel insulation on the lead ends must be removed before they can be soldered. This can be done by scraping the enamel off with a sharp hobby knife and applying heat from your soldering iron until any remaining enamel melts, after which the leads can be tinned and soldered in the usual manner. Now we need to make a tap connection to L2. Its ends are labelled on the PCB with “1” on the lower end and a “2” at the other end. The middle “3” connection is made using a short length of tinned copper wire soldered onto the coil side as shown. It is placed on the second 330pF A GND10nF 1 F BB207 10nF Silicon Chip 10nF POWER STEREO 10nF 47nF ZD1 470 120k 3.3k 15nF 15nF 1 F REG1 7805 IC6 LM4865 3.3k 1 F L 1 F R 1 Australia’s electronics magazine + BALANCE 1 10k GND 220 F CON3 SPEAKER R 10k 1 F 1 F 100nF VR7 100k IC5 LM4865 3.3k K VC3 BB156 47k 68k VC2 68k 220pF 10k Q3 30C02CH 4.7k 2.2pF E 47k B 10k LINEAR 4.7k 560 10k 10k L3 TP1 Q6 2N7000 L 100nF + 220 F 100k 47k 47 VR6 VOLUME 4.7pF 100 F TP5V 10 F 1 C 100 F IC4 MC1310P 2.2 F 64 220nF 16k 100k 10k LINEAR 470nF TP 19kHz 1k SET 19kHz 3.3k +5V 100k 1 F 3.9k 470pF VR5 5k VR4 500k 220nF TPREF 9V BATTERY HOLDER IC3 CA3089 22nF L6 SQUELCH 1k 22 H 5.1k 0V FM RADIO 100nF TPTUNE L5 TPSIG 10nF 1 20k VR1 TUNING L4 SILICON CHIP Q7 SUP53P06–20 33k 22nF 20k IC1 LMC6482 10k 10k GND VC1 TRIM 10nF 1 10nF 10nF 1 330 330 10k 10k 1 VR3 10k 10 F SHIELD 10M7FA XF1 VR2 10k VC2 TRIM 4.7k 4.7k 39pF SHIELD 10 220pF 47 D 10k 10nF 10nF S FB2 NE592 IC2 10nF 10nF T1 Q2 BF992 330 10nF 10k VC1 BB207 47pF G1 G2 L2 1 68k 68k 2 10nF 330 GND 220pF 1 470k 1k FB1 S 06109184 Antenna Bracket L1 G1 G2 10k 10nF D 47 Q1 3 BF992 10k 47pF 06109183 Fig.6: this tiny PCB is used to attach the antenna to the main board. It allows the antenna to project out from the PCB far enough that it sits outside the plastic case, and the antenna can then be folded along the top of the Radio, or rotated and extended to be vertical during use. SILICON CHIP ANT. Fig.7: this simple shield PCB has copper on both sides along with two exposed pads, to solder to PC stakes on the main board or directly to a pad on the main board. This connects the copper on the shield board with the main PCB ground, preventing signals from coupling between components on either side of the shield. Two identical shield shield boards are used in this design. 15V 1W Fig.5 shows the coil winding details. There are four air-cored coils, L1-L4. L1-L3 are identical and are made by winding 5 turns of 0.8mm diameter enamelled copper wire onto a 5mm drill bit shaft or other cylindrical former. Before winding, stretch the wire straight by clamping one end in a vice and pulling the other end with a pair of pliers. Be sure to wind these coils in the direction shown. If the coils are wound in the wrong direction, they will not fit correctly on the PCB. L4 is made from a half-turn of the same wire. After winding, install the coils on the board with the lower part of each coil 5mm above the top of the PCB. 150 Winding the coils winding from the “1” end. You will need to scrape some of the enamel off the coil so solder will adhere to it. Transformer T1 is made by winding two coils onto a miniature Neosid former. Solder one end of the 0.125mm enamelled copper wire to pin 2. As with L1-4, use heat or a sharp knife to strip away some of the enamel from the wire end, then wind it around the pin, close to the former, and solder it in place. Pass the wire around the indent in the former on the side so the wire won’t contact the metal can when installed. Now, starting from the bottom of the former, wind on 25 turns with each turn adjacent to the previous turn. Do not place windings on the former above the flange near the top. This section is reserved for the cup core to fit. After this, terminate the free end of the winding on pin 1, again making sure that the wire is fed via the indent. The second winding for T1 is placed over the first winding, with five turns terminated to pins 3 and 4. Again, ensure the wires are routed via the former indent. The winding direction is not important. Inductor L6 is wound similarly to T1, except that there is only one wind- 100k board via a solder fillet between the two PCBs. Q5 2N7000 1M LOUDSPEAKER siliconchip.com.au Use a hacksaw to cut the tuning potentiometer (VR1) and the volume control potentiometer (VR6) shafts to 17mm, measured from where the threaded boss starts. Feed VR6’s shaft through the PCB from the component side. The small locating spigot on the side of the pot fits into a corresponding slot on the PCB. Secure the pot with its washer and nut on the other side. Now bend the potentiometer pins so that they touch the PC stakes and solder them in place. You also need to solder the pot body to the fourth PC stake to ground it to the circuit, but the body is passivated to prevent corrosion. This makes it almost impossible to solder, so you need to scrape away S1 9VDC (CENTRE +) CON1 150 PHONES CON2 siliconchip.com.au Existing endstop SILICON CHIP Preparing the potentiometers REQUIRED PIECE 06109185 ing of 23 turns, terminated to pins 1 and 2. Place a cup core over each former, add the metal can and insert into the T1 and L6 positions. Make sure you have the correct one in each place (T1 has the two windings) before soldering the pins. The F16 slugs can now be screwed in the top, but do not use a screwdriver as it will crack the core. Use only a small brass or Nylon trimming tool to screw in the slugs Curved PCB Pot travel stopper SC CUT 20 1 9 Fig.10: make two cuts on the Pot Stopper PCB, where shown here, to separate the thin arc section from the rest of the board. This piece of fibreglass laminate is then placed inside one of the potentiometer bodies, to limit its angle of rotation to exactly 180°. some of the passivation layer with a file or hobby knife first. Potentiometer VR1 needs some modifications before being installed. First, remove the rear metal shell by slightly bending the four flange tabs that clamp it to the pot. We’re doing this so that we can insert a ‘stopper’ piece to reduce the pot rotation to just 180° rather than 300°, to suit the tuning dial. The stopper is a curved piece of a small PCB. You need to cut out the middle section, along the white lines shown on the PCB and in Fig.10. You END STOP MODIFICATION TO ‘ALPHA’ POTENTIOMETER Flange tabs BACKSHELL Fig.11: this shows how the Pot Stopper fibreglass section sits inside the pot body once the shell has been removed. Crimp the existing metal endstop over the pot stopper to hold it in place, then once you have checked the pot travel, reattach the rear shell using the flange tabs. can cut it with sharp side cutters or with a hobby knife, then file the ends smooth. Cut the corner of the original end stop inside the pot rear shell with side cutters and bend the pieces open a little, just enough for the curved PCB piece to be inserted. Locate it centrally around this preexisting end stop, as shown in Fig.11, and then bend the metal pieces back over the PCB piece so it is held in place. Reassemble VR1, making sure that the shaft is rotated so the flat on the Fig.8 (left): this PCB overlay diagram shows where to fit the components onto the board before soldering. Ensure that the polarised components (zener diode, electrolytic capacitors, Mosfets, transistors and ICs) are the right way around. Also, pay careful attention to ensure each component installed is of the correct value and type. Fig.9 (right): and     here are the very few components on the back side of the PCB – LEDs 1 & 2, plus the only SMD on this side of the board, Mosfet Q4. Make sure that the longer lead of each LED goes to the pad marked “A” in each case. Cut open endstop, place curved PCB inside & crimp in place with endstop tabs TUNING C B E Q4 30C02CH VOLUME Australia’s electronics magazine K A LED2 STEREO K A LED1 POWER December 2019  65 shaft is toward the three terminals first. That’s so the plastic rotating piece at the end of the shaft is positioned with its travel stopper opposite the PCB arc piece. Replace the metal shell and test that it now rotates through 180°. Then bend the tabs over again to secure tightly in place. As with VR6, feed it through the PCB and ensure the locating lug is in the slot provided before securing it with the supplied washer and nut. This pot is wired to the PCB using short lengths of 0.7mm tinned copper wire fed through the PCB pad holes and each of the three riveted connection points on the pot. Solder these wires to the PCB and then to the pin ends of the metal tabs on the pot. Do not solder at the riveted points, where the wires pass through, as this could damage the connection to the pot’s carbon resistance element. Now remove some of the pot body passivation near the 0V pin and solder a short length of tinned copper wire from the 0V terminal of VR1 to the pot shell, as shown in the photos. Grounding the pot body provides some shielding to avoid noise pickup through the pot. Now fit the battery holder, on/off switch (S1), DC socket (CON1) and headphone socket (CON2). The battery holder is held in place with short selftapping screws inserted from the underside. The power switch and headphone socket are mounted directly on the board. Also install locking polarised header CON3 now. Its orientation is not critical. Speaker mounting The speaker is fastened to the PCB using four M3 screws and nuts. The board has eight mounting holes, two sets of four on two different circumferences. So use the correct holes for your particular loudspeaker and orientate it with the terminals nearest to the bottom edge of the PCB. Crimp and/or solder a short length of figure-8 wire to the pins for the polarised header plug and insert them into the plastic shell. Connect the other end to the speaker terminals, then plug it into CON3. The two LEDs are located on the dial side of the PCB and sit flat along the PCB, with their lenses pointing towards the dial (see photo). It would be a good idea to fit two different-coloured LEDs so you can later tell which 66 Silicon Chip one is illuminated. Bend the leads to insert into the PCB holes, making sure that in each case, the longer lead is in the anode position, marked “A”. Antenna mounting A small antenna adaptor PCB shown in Fig.6 is used to extend the connection point upwards, so that the antenna can be outside the enclosure. It is attached to the main PCB using an M3 screw and two nuts. One nut is sandwiched between the antenna adaptor PCB and the main PCB, and the other at the underside of the PCB. The electrical connection is made via the antenna input PC stake. The antenna is attached later, once the Radio is in its box. There are several ways to attach the antenna. The antenna mounting hole is smaller than 3mm so it can be tapped for an M3 thread. This allows the antenna to be secured just with an M3 screw. If you don’t have an M3 tap, the hole can be drilled out to 3mm. The antenna then attaches with an M3 screw with washers on each side. An M3 nut holds the antenna reasonably tight in place. You can either use thread lock (such as Loctite 222, 243 or 263) or a locknut to prevent the nut coming loose. A Nylock M3 nut could also be used. Initial testing Even if you have assembled the Radio precisely as we have described so far, there is little chance that it will work satisfactorily when you first power it on as it needs to be ‘aligned’ to work properly. Before installing the battery or connecting power, check the assembly carefully to ensure that all parts are in their correct locations and are correctly orientated. The underside of the board should also be checked for missed solder joints and short circuits. Assuming that everything is correct, it should be safe to connect power now. But to be sure there are no immediate problems, you should measure its current draw when you do. Apply 9V with switch S1 off (out) and switch your multimeter to read current. Connect one of its probes to one of the centre pins of S1 and the other to one of its rear-most pins. This will effectively connect power to the circuit via the multimeter. A current reading over 100mA at this stage could mean there is a problem. If so, remove the probes immediAustralia’s electronics magazine ately. Check the board again carefully for incorrectly placed components and shorted pins on ICs or between soldered pads. If the power LED (LED1) does not light, it is either installed with the incorrect polarity or power is not reaching it. There could be a short somewhere across the power rails, which would be indicated by a very high initial current draw. Locate the source of the problem before switching on again. Assuming it’s drawing a modest current and LED1 is lit, proceed to make a series of voltage checks. We listed voltages expected at various parts of the circuit on the circuit diagram. These voltages are approximate and assume a supply voltage of exactly 9V. They were measured on the prototype using a digital multimeter. Check the 5V supply between TP5V and GND. This should be between 4.75V and 5.25V. If any measured voltages differ by more than 20% from our figures, there is probably an incorrectly placed component on the board. Aligning your Radio To make the alignment easy, the circuit should initially be set up according to the following procedure. Note that all adjustments to the ferrite slugs in T1 and T2 must be carried out using a proper trimming tool. Do not use a screwdriver in the ferrite slugs, as this can easily crack them. Measure the length of coil L1 and stretch or compress it until it measures 10mm end to end. Similarly, set the length of L2 to 15mm and L3 to 10mm. Rotate VR2, VR3 and VR4 fully anticlockwise. VR3 and VR4 are multiturn trimpots so you should do this by turning the top screw of each one anticlockwise at least 20 times. You may hear soft clicks when they reach the end of their travel. IF alignment The alignment procedure involves using the IF Alignment Oscillator described in the accompanying panel. Its output is fed directly into the antenna input, to the left of coil L1, on the FM receiver board. Don’t forget to connect the GND terminals of the two boards together as well. There is sufficient signal from the IF oscillator to enable the 10.7MHz signal to pass through the 88-108MHz bandpass filtering of the first stages to reach siliconchip.com.au The front side of the Radio is a shiny black acrylic but the rear, as shown here, is crystalclear – so that you (and everyone else!) can admire your handiwork . . . the mixer IF output. Power for the IF Alignment Oscillator can be derived directly from the Radio’s 5V supply, between TP5V and GND, using a suitable length of hookup wire. The step-by-step alignment procedure for the IF circuitry is as follows: 1) Power up the Radio and alignment oscillator. 2) Connect a multimeter set to a low DC volts range between the “Signal” test point near IC3 and a GND test point. 3) Adjust trimpot VR8 on the IF oscillator for a multimeter reading of 3-4V. 4) Adjust the slug in T1 for a maximum reading. If the reading goes above 4V, adjust VR8 anticlockwise, so the voltage stays in the 3-4V range. Then re-adjust T1 for a maximum reading and repeat until you can’t get it to increase any further. 5) Connect the multimeter between TP REF and TP TUNE and adjust the slug in inductor L6 for a 0V reading. That completes the alignment of the IF stages. But the local oscillator and RF amplifier stages still need to be aligned. Remove the FM IF Oscillator board and attach the telescopic antenna to the antenna extension PCB using a screw and nut. Local oscillator adjustments There are two methods for tuning the local oscillator. It needs to be adjusted so that it tracks the tuned signal frequency, always being 10.7MHz lower. If you have access to a frequency meter or digital oscilloscope that can measure in the 100MHz region and siliconchip.com.au show a frequency reading, that is ideal. A 50MHz oscilloscope would probably be OK, even though the signal level will be down due to its roll-off above 50MHz. Connect a 10:1 probe to TP1 (near coil L3) and connect the ground lead of the probe to the PCB GND. For best results, to prevent any frequency shift due to the probe loading, include a series resistor between TP1 and the probe. A 1kΩ resistor or higher value may be used, but ensure the resulting reduction in signal level does not prevent the signal frequency from being read reliably. During this procedure, keep the probe away from L3, to avoid affecting L3’s tuning. Set the tuning dial to 88MHz, then adjust L3 so that the frequency meter or scope shows 77.3MHz. Squeeze L3’s windings together slightly to lower the frequency, or stretch it to raise the frequency. Then set the tuning dial to 108MHz and adjust VR3 for a reading of 97.3MHz. Now return to the 88MHz tuning dial position and re-adjust L3 for 77.3MHz. Return to the 108MHz position and re-adjust VR3 for 97.3MHz. Repeat until no further adjustments are necessary. If you don’t have access to a frequency meter, then a commercial FM radio can be used instead, as follows: Tune in a strong local station at about 98MHz on the commercial radio and make a note of the exact frequency. Switch the commercial radio off and tune in the same station on your Radio. It will probably not be anywhere near the indicated dial frequency, since the local oscillator has not yet been adjusted. Australia’s electronics magazine If the indicated frequency is too high, squeeze L3 so that its turns are closer together. Conversely, if the indicated frequency is too low, stretch L3 so that its turns are further apart. This will get the alignment started at the middle of the FM band. Then find a station near 88MHz on the commercial radio, tune it in on your Radio and re-check the adjustment of L3 and the position on the dial. Re-adjust L3 until the indicated frequency matches the station frequency. Find a station up near 108MHz and use the same procedure to adjust VR3 so that the station lines up with the dial calibration. Repeat tuning at the 88MHz and 108MHz ends of the dial until the stations appear at the correct locations on the dial. RF amplifier adjustment The RF amplifier is the next section to be adjusted. The procedure is as follows: 1) Connect a multimeter between TPSIG and GND and tune to a station near 88MHz. Adjust L2 for a maximum reading. Squeeze the coil slightly (so that the turns are closer together) to lower the frequency, or stretch it to raise the frequency, but note that you won’t know which way is ‘right’; you just have to try both and see which helps. Shorten the telescopic antenna should the reading on the multimeter go above 4V. Keep the signal reading within 3-4V while adjusting the antenna to keep this range. 2) Tune to a station around 104108MHz and adjust VR3 until the December 2019  67 received frequency matches the indicated frequency. 3) Adjust VR2 for a maximum reading on the multimeter, again making sure that the reading does not exceed 4V. Re-adjust the antenna length if necessary. 4) Repeat steps 1-3. This is necessary since adjustments at one end of the band also affect the other end. Front end tuning Tune to a station near 100MHz which gives a reading of 3-4V at TPSIG and adjust L1 for a maximum reading by squeezing or opening the coil. Check that the Radio now can tune stations across the entire FM band, from 88-108MHz, and that the dial calibrations are correct. Check also that no background noise is evident when you tune to strong local stations (a good antenna helps). If the dial calibrations are incorrect or local stations are noisy, go back and carefully repeat the alignment procedure. With a good strong signal being received, the IF slug in T1 can be re-adjusted to peak the reading at TPSIG. Additionally, for the best result, adjust the slug in L6 for 0V between TP REF and TP TUNE. Tuning the stereo demodulator Adjust VR5 for a 19kHz reading at the 19kHz test point. If you don’t have a frequency meter capable of measuring this, you can adjust this while receiving a strong station with the headphones plugged in. Adjust VR5 to the middle of the range where the stereo LED lights up, ie, position it halfway between the two positions where the stereo LED is just off. you’ll want to put it into the purposedesigned acrylic case. Its appearance is not unlike the mantel radios of yesterday, only it is glossy black! The case measures 327 x 155 x 58mm (w x h x d) and the front, sides, top and bottom are made from a very smart high-gloss black acrylic. The back panel is transparent, so that everyone can admire your handiwork. It has holes in the left-end panel for the on/off switch, the DC power plug and the 6.5mm headphone socket. On the front panel, attractive slots are milled for sound output immediately in front of the speaker. At the right end, there’s a matching 105mm hole for the clear acrylic tuning “dial” which reveals the screen-printed PCB underneath, showing the major radio stations. We glued a large knob to the centre of the dial to make it easier to use – this also holds the dial to the shaft. Immediately underneath and to the left of the tuning dial is the single volume control. The case simply slots together and everything is held in place by four 46mm long pillars which go from front to back. We’ve also made provision on the bottom front of the case for a pair of rubber feet which can angle the whole receiver back slightly. Again, this is entirely optional. ~10mm M3 SCREW BACK PANEL 25mm LONG M3 TAPPED SPACER M3 NUTS & WASHERS (SPACE AS REQUIRED TO ADJUST TOTAL LENGTH) Squelch control VR4 sets the squelch control. Squelch is designed to mute the interstation noise while tuning between stations. We found that this adjustment is best left with VR4 in its fully anticlockwise position where there is no muting. You can set the control to a more clockwise position if that is your preference. Putting the case together Because this Radio is self-contained (ie, entirely on one PCB), it is quite happy working without a case. But if you want a really professional finish, or are going to take it with you, 68 Silicon Chip 15mm LONG M3 TAPPED SPACER 46mm ~15mm M3 STUD (15mm M3 SCREW WITH HEAD REMOVED) M3 NUTS & WASHERS AS REQUIRED PCB FRONT PANEL ~15mm M3 SCREW SC 20 1 9 Fig.12: you need four 46mm M3 threaded standoffs, but just try to buy them! We made ours from 15mm and 25mm standoffs, joined with an M3 “stud” made from a headless 15mm screw. Nuts and washers were used to pack it out to 46mm long. Australia’s electronics magazine Remove the nuts from the volume control pot and headphone socket, if fitted. Start with the front panel. Insert four M3 x 15mm screws through the four holes near the edges and put a washer and nut on each to hold them in place. Now slide the receiver PCB down over these screws, orientated so that the speaker sits behind the slots and the dial markings behind the 105mm hole. Slide the left end panel into its slots on the front panel, at the same time engaging the on/off switch shaft and the 6.5mm headphone socket. You will probably have to lift the PCB on this end to allow this. When in position, refit the nut onto the headphone socket. This will hold the end panel in place. You can then slide the bottom, top and right end panels into place, with their tabs fitted into the slots on the front panel and each other. Once you’ve reattached the nuts and washers for the pots and sockets, you can then fit the three knobs (for S1, VR1 & VR6). Threaded standoffs It’s not easy to buy a threaded standoff long enough (45mm+) to hold the rear panel onto the front panel. We made ours with a combination of 15mm and a 25mm M3 threaded standoffs, M3 studs to join them into single 40mm lengths, plus a few M3 nuts and washers to end up with the 46mm length required – see Fig.12. The “stud” which joins the 15mm and 25mm lengths was simply a short (15mm) M3 screw with its head cut off with a hacksaw. You will probably need to clean up the end with a file, then run a nut over the cut-off section to re-form the thread after cutting it. If you use Nylon or Polycarbonate screws, the head can be cut off with side cutters. We used two M3 nuts between the two standoffs as additional spacers. The overall length of the standoff is 46mm. Given that nuts can vary in height, simply vary the number of nuts and/or washers to make your standoffs 46mm long. You will need four of these. The bottom ends screw onto the M3 screws which pass through the case front panel (already fitted with a nut) and then the PCB. The top ends are fastened using four M3 screws which hold the rear panel in place. SC siliconchip.com.au A simple 10.7MHz IF Alignment Oscillator Here’s an easy project which will make aligning the IF stages of your Super-9 FM Receiver really simple. It generates a 10.7MHz sinewave with a minimum of parts. T D1 1N5819 K 8.2pF 12 IC7d XF2 10M7FA 11 13 14 IC7c 8 3 2 4 5 OUTPUT LEVEL 7 10nF VR8 1k 330pF 6 IC7b OUT 1N5819 10nF A 20 1 9 IC7a 270 330 SC  IC7: 74HC00 1 270 10 +5V 0V 1M 9 A 100nF 0V K FM IF ALIGNMENT OSCILLATOR 0V 270 8.2pF VR8 1k IC7 74HC00 LEVEL 5819 100nF 1M 10nF OUT 270 D1 XF2 330 C 2019 REV.B 06109182 10M7FA 10nF 0V Fig.2: install the parts on the FM IF Oscillator board as shown here. Take care to ensure that IC7 is correctly orientated and insert PC stakes at the four external wiring points. 10.7MHz Alignment Oscillator Fig.1: the IF Alignment Oscillator circuit is an inverter based on NAND gate IC7c and ceramic filter XF2. Its output is filtered using an RC low-pass filter to give something approximating a sinewave. The output frequency is a tad over 10.8MHz, which is near enough to 10.7MHz for our purposes. +5V his FM IF (intermediate frequency) Oscillator generates a 10.7MHz sinewave for aligning the IF stages of the Super-9 Stereo FM Radio (it would be useful for aligning other radios too). It’s built on a small PCB, requires no adjustments and can be assembled in a few minutes. It is based on a single high-speed (HC) CMOS NAND gate (IC7c) and a 10.7MHz ceramic filter. IC7c is in a standard oscillator configuration. Its input pin 9 is wired to the positive supply, so it behaves as an inverter. It is biased into linear mode using a 1MΩ feedback resistor between its pin 8 output and its second input at pin 10. The 10.7MHz ceramic filter (XF2) is connected in parallel with the feedback resistor, along with an 8.2pF capacitor to provide the correct amount of capacitive loading. The associated 330Ω and 270Ω resistors provide the correct impedance loading for XF2. The 330Ω resistor is AC-coupled to ground via a 10nF capacitor to avoid affecting the DC voltage at pin 10. The 270Ω resistor at pin 8 is smaller than the specified 330Ω resistive load for XF2 because of the nominal 60Ω output impedance of IC1. The resulting 10.7MHz waveform at pin 8 is filtered using a 270Ω resistor and a 330pF capacitor to produce a rounded triangular waveform. This is then fed to the output via level control VR8 and a 10nF capacitor. Although the nominal output frequency is 10.7MHz, it is in fact closer to 10.8MHz because of the phase characteristics of the ceramic filter. This 100kHz difference is of no consequence since the 10.7MHz ceramic filter used in the FM Superhet Stereo Radio has a bandwidth of 280kHz. The adjacent oscilloscope grab shows the waveform as measured at the output. Power for the circuit is derived from a 5V source via reverse polarity protection diode D1. You can use the 5V rail on the Super-9 Stereo FM Radio to power the oscillator. 330pF Construction The output of the oscillator shows a reasonable 228mV sinewave at about 10.85MHz – certainly “close ’nuff!” siliconchip.com.au The FM IF Oscillator is built on a single-sided PCB coded 06109182, measuring 52 x 30.5mm. Fig.2 shows the parts layout. Install the parts as shown, taking care that IC7 and D1 are both correctly orientated. XF2 has a line marking on the bottom of its package to aid with orientation. A small dot on top of the package also shows the pin 1 location. This needs to match the orientation shown on the PCB overlay. PC stakes can be installed at the power supply and output wiring points, so that the unit can be easily connected to the receiver. To test the assembly, connect a supply and check that the voltage between pins 7 and 14 of IC7 is about 200mV less than the supply voltage applied to the input. If this is OK, use a multimeter set to read DC volts to check that pin 8 is sitting at about half this supply. This is the average level of the 10.7MHz signal from IC7. Alternatively, if you have a frequency meter or oscilloscope, then you can check the output for a 10.7MHz waveform. SC Australia’s electronics magazine December 2019  69 FIRST LOOK: TIM BLYTHMAN REVIEWS THE ALL-NEW When we reviewed AD19, we found some handy new features like component re-routing, follow mode for track routing and an updated layer stack manager. The folks at Altium have not rested on their laurels and the new version, Altium Designer 20, should be available to the public at about the time this article goes to press. We got to try a beta version and here is what we found. I n case you aren’t familiar with it, Altium Designer is EDA (electronic design automation) software that traces its roots back to an early Australian PCB design tool, Protel PCB. We use Altium Designer at SILICON CHIP for all our PCB designs. We reviewed AD18 in August 2018 (siliconchip.com.au/Article/11189) and subsequently, AD19 in the April 2019 issue (siliconchip.com.au/ Article/11527). You may recall that AD18 was quite a revolutionary step from previous versions while AD19 continued to add features and iron out bugs. So we were keen to see what the latest version had to offer. The “Roadshow” In October this year, we were invited to Altium’s Roadshow 2019 event at Sydney’s Olympic Park, where they revealed (among other software), Altium Designer 20. The notion of continuous improvement was emphasised at the Roadshow. The folks at Altium are aware that Altium Designer is a leader in the EDA market. But they also note that they cannot stay in such a position without continually stepping up their offering. The Roadshow event also covered upcoming Altium products such as the Altium 365 platform. Altium 365 is a cloud-based platform that allows collaboration between the various stages of electronics design and manufacture. One benefit of being cloud-based, besides allowing users to roam easily, is that users not directly involved with PCB design (and who would not have the Altium application) can view and comment on designs. This could be handy for people involved in manufacturing or mechanical design, so they Screen1: the Schematic Editor looks much the same as in AD19, although you may notice some slight differences. This is due to the new DirectX rendering, and it is generally easier to see. Zooming and panning around the schematic is considerably smoother, too. 70 Silicon Chip Australia’s electronics magazine siliconchip.com.au Screen2: we created an exaggerated creepage rule to show how it works. Note how the indicated creepage path avoids the slot. AD20’s creepage rule can even handle paths crossing from one side of the board to the other, taking PCB thickness into account. This rule might catch situations which manual creepage checking could miss. can see details of the design without needing an Altium license. Since our team is small, with typically one or two people doing PCB and mechanical design and assembly on a given project, it’s hard for us to put something like Altium 365 through its paces. But we imagine it will be quite useful for larger teams, especially if they are geographically distributed. The Roadshow also took some time to explain some features which have been part of Altium Designer for a while. A quick poll of those at the Roadshow indicated that a good number are still using versions as old as AD14; it’s clear that the Altium team is aware of Screen3: the High Speed Return Path rule checks that a signal return path (such as a ground plane on another layer) is correctly placed along a highspeed signal line. If it is missing, as in the upper left corner shown here, or has less overlap than specified, a violation is generated. The Impedance Profile options come from the Advanced Layer Stack Manager. New features • Improved schematic editor • Dynamic schematic compilation • Any Angle Routing and improved trace editing • Creepage path Design Rule • And more... this and want to let users know about the benefits of using the newer versions, with their improved features. Altium Designer 20 Let’s start by looking at some of the newer features in AD20. We tested version 20.0.6; the final release version will almost certainly be different. We installed it alongside AD19 so we could make comparisons. ensure the PCB layout is correct. The Schematic Editor has been completely rewritten for AD20. It now makes use of DirectX for graphics rendering, so using it is much smoother. It has been sped up so much that ‘compilation’ happens in real time. The ‘Compile’ menu option is still there, but it just brings up the dialog box summarising the compilation results. (‘Compiling’ a schematic essentially checks that there are no glaring errors, like duplicate component designators or important unconnected pins.) As a result, the Schematic Editor now feels much more snappy. Screen1 shows its new appearance. As well as being faster, we think it is also much softer on the eyes. For example, when Installation Screen4: this dialog shows the new text justification options, below the font type selection. Existing projects without text justification set will remain unchanged until a justification setting is chosen. The location coordinates are automatically re-calculated when the justification is changed so that the text stays in the same place. siliconchip.com.au The install process for AD20 is relatively straightforward and similar to that for AD19. A small 23MB installer program downloads and installs the full program. In total, around 2GB was downloaded and the install took up around 5GB of storage space. After opening Altium Designer 20, we were given the option to import settings and had to select the license to use. After that, it opened the files we had open the last time we used AD19. The whole upgrade experience was quite seamless, and it felt very much like we were continuing where we left off with AD19. Schematic Editor While you might think that Altium Designer is focused on PCB editing, creating a schematic is essential to Australia’s electronics magazine Screen5: although the differences are quite subtle, if you look carefully, you will see that the labels next to CON1 are not aligned as well as for CON2. But placing the text for CON2 took a fraction of the time, because of the ability to right-justify the text and centre it vertically so each string lines up exactly with the pin centres. December 2019  71 Screen6: the new modal properties dialog box (at left) with the properties panel (in AD19 style) at right. While the default behaviour for AD20 has changed to be modal, the Preferences can be changed so it is not modal (PCB Editor -> General -> Double Click Runs Interactive Properties). A similar option for the Schematic Editor is under the Graphical Editing item. you zoom in and out, the font and line weight doesn’t ‘jump’ in steps like it used to, and you can read smaller text when zoomed out a bit more easily. It’s a subtle difference, but we feel that it’s an improvement. Laying traces There are still some times when we’re using AD19 that we go to move a track which isn’t quite in the right place and it doesn’t go where we want it to. As a result, it is often easier to ‘rip up’ the trace and lay it from scratch. But with AD20, this has improved immensely. Now, when moving a track, it also takes into consideration the connected traces (at each end). So the result of trying to move traces is now much more intuitive and obvious. Track laying has been improved too, with improved any-angle routing. This too feels smarter. We saw a demonstration of BGA (ball grid array) escape routing at the Roadshow. This was shown to be a lot more fluid and intuitive in AD20 than its predecessors. Fortunately for us (and you, dear reader, who may be assembling our projects), we have not used any BGA parts yet. But we did try routing one of our existing projects with the any-angle setting. The result is reminiscent of the 72 Silicon Chip carefully curved, hand-drawn PCB designs from the 1970s. Even if you don’t work with tiny chips, it’s a great option if you’re going for that retro look (Screens 7&8). It may also be a way to cram tracks into a small gap in your layout that would otherwise seem impossible! Design Rules Design rules allow a PCB design to be checked for validity and safety; the rules are set according to manufacturer specifications (eg, minimum trace width and spacing) and electrical standards and regulations (for example, high-voltage track clearance). The PCB Editor in AD20 has some new design rules. The most useful of these is creepage distance. Enforcing this is most important in mains-rated designs, where minimum creepage distances are specified in many standards. Creepage distance is slightly dif- ferent from clearance distance in that creepage is that path between two conductors along the surface of the PCB, while clearance is simply the straight line distance. This is because current may flow along a nominally insulating path (eg, the PCB substrate) in the presence of surface contaminants. One way of increasing creepage distances is to mill slots in the PCB, which removes a surface on which contaminants can collect and form a creepage path. You will have seen these slots on board designs we’ve previous published, such as the Opto-Isolated Mains Relay from October 2018 (siliconchip. com.au/Article/11267). Screen2 shows how the (exaggerated) creepage rule is applied. The online rule checking and violations display allows you to see immediately whether changes to the design will fix the problem. In the case shown, the design rule violation could be eliminatVias that are not covered in solder mask can cause problems; here’s an example where we forgot to tent them in an early prototype (for our Stackable Christmas Tree). They can easily be shorted accidentally and can corrode, plus they make it look like the board is missing some components. Australia’s electronics magazine siliconchip.com.au Screen8: the Interactive Routing Properties are shown by pressing the TAB key when routing; the Any Angle Routing option is shown under Corner Style, where the mouse pointer is located. Routing is resumed by pressing the ESC key. Screen7: we routed our Tiny LED Xmas Tree PCB from the November 2019 issue using any-angle routing. It was easy to achieve a working result, especially around the unusual board edge shape. The result looks less engineered and more organic; perhaps that’s appropriate for a tree… ed by lengthening the slot. Sometimes this creates an alternative creepage path, but this can now easily be seen and rectified. High-speed return paths In our review of AD19, we explained how the Advanced Layer Stack Manager could be used to calculate and set the impedance of paths in high-speed designs by using information about dielectric thickness, trace width and ground plane layers. This makes it easier to tune highspeed designs correctly. In practice, variations in the return path can compromise the assumptions made in these calculations. The new High Speed Return Path rule can be used to ensure that the return path (in the ground plane layer) is adequate. The selected impedance profile determines to which layer the high-speed signal is referred. The amount of overlap and whether voids due to pads or vias are included can also be selected. We’re unlikely to need this feature, especially since many of our boards only have two layers, but many other engineers will make good use of it (Screen3). Tented vias By default, vias placed in the PCB Editor are not ‘tented’, ie, placing them opens the surrounding solder mask. Unless you need a test point (and if you do, you should place one explicitly), it’s generally better to have the via covered in solder mask. There’s less chance of siliconchip.com.au short circuits that way. We generally place tented vias, but it’s quite easy to end up with untented ones in a design by accident. The new “SolderMaskExpansion” design rule allows all vias to be tented by default. The rule can be found under Design Rules -> Mask -> Solder Mask Expansion (see Screen9). Better text support Improvements have also been made to text objects in the PCB Editor. This is definitely something that we will use, especially as our designs have more text on the silkscreen (to assist with manual assembly) compared to designs opti- mised for machine assembly. We often have rows of pins with identifying text next to each one. Unless the text sits to the right of the pins, aligning it nicely was a tedious, manual job. Now there is the option to set the justification of each text object, so aligning by the top, bottom, left, right or centre is now possible. Screen4 shows the updated text object properties box. Screen5 shows the difference this makes. The text accompanying CON1 was laid out in the way have previously done this with Altium Designer 19. The snap grid causes a small amount of unevenness, and each item had to be placed by hand. Screen9: this shows the design rule to cover all vias in solder mask film automatically. Set both options to “Tented” and all your vias will almost disappear. Australia’s electronics magazine December 2019  73 Screen9: creating the symbol for an Arduino shield with the Symbol Wizard. You can use a spreadsheet to generate the pin names and then paste them back into the table. or perhaps due to a circuit revision to an already produced board. Sometimes components added to a PCB are stacked up haphazardly. There is an option to move these components to a selected area, under Tools -> Component Placement -> Arrange within Rectangle. After selecting the parts, choose this menu option and then drag a rectangle with your mouse pointer. All the components are placed neatly inside it. This is an efficient way of tidying the layout before starting the serious job of placing (or adjusting) components. Place components from file CON2 makes full use of the justification feature of AD20. We created the first text object and aligned it to the right (horizontally) and centre (vertically), so that it lined up with the pin centre. We then copied and pasted it for the other pins, then edited the text labels. As a result, all the text objects are aligned perfectly, in a fraction of the time. Panels and properties The default behaviour of the object property box has changed in AD20. Previously, you could double-click on a part to open its property dialog box and make changes. Alternatively, you could open the properties panel and make changes there. Now the property dialog box is modal by default, meaning that it must be closed before working in the main application window. The dialog box has been rearranged to make more settings visible without scrolling. See Screen6 for a comparison of the new dialog box against the older (but still available) panel. We’re slowly getting used to the idea of clicking on Panels -> Properties to bring up the panel for making changes to multiple parts. There is a setting to revert the behaviour to be more like AD19 if you find you don’t like this change. But we think many who were used to the pre-AD18 workflow will welcome it. A similar arrangement is found in the Schematic Editor. This is handy for choosing component footprints, as it 74 Silicon Chip involves less scrolling than in AD19. Tips and tricks Here are some things we learned at the Altium Roadshow which are not specific to the new version, AD20. There is a component footprint wizard in the PCB library editor which allows many common component footprints to be easily created by entering such figures as the pin count, pad size and spacing. Even non-standard footprints can be created by using the wizard and then modifying the result. There’s also a symbol wizard to ease the creation of schematic symbols. When editing a schematic library, this can be found under Tools -> Symbol Wizard. Although it only appears to generate square boxes with pins along the sides, it also allows the various pin types, designators and other data to be edited in a small spreadsheet. The real secret to this tool is that you can copy and paste data from a separate spreadsheet program, making automatic creation of families of parts much easier. Even existing parts can be edited with the symbol wizard; it’s probably the best way to make wholesale changes to a symbol. Component placement A critical step in the PCB design process is component placement; efficient trace routing is not possible without proper placement. We learned about two handy tricks for doing this. The first is simply a tool for tidying up your PCB as you transfer it from your schematic, either on the first pass Australia’s electronics magazine This feature is intended for use with automated component placement during manufacture, but it can come in handy for a variety of other tasks. You can generate a file containing a list of component identifiers, X/Y coordinates and rotations in a humanreadable (and editable) format. This is done via the File -> Assembly Outputs -> Generate pick and place files. This creates a file with a .TXT extension but you can edit it and then rename it to .PIK. This file can then be loaded via the Tools -> Component Placement -> Place and all the components will be moved into their new positions. This could be a speedy way to place components on a grid, without having to do it manually! Conclusion We have no hesitation in switching from AD19 to AD20. The speedups in the Schematic Editor alone are enough to convince us. The only other change in workflow is the new properties dialog behaviour – but as we explained, you can revert to the old behaviour if you prefer it. The big lesson we got out of the Altium Roadshow is that there are great features that we (and many other Altium users) are not yet aware of, which can be used to make PCB layout jobs even easier. SC Free trial of Altium Designer You can get a fully-featured 15day evaluation version of Altium Designer for free. If you haven’t yet tried the software, visit www.altium. com/free-trials/ for more information. This page also has information about free trials for other Altium products such as the Concord Pro Library Manager. siliconchip.com.au SERVICEMAN'S LOG Two devices what failed th’idiot test Dave Thompson Murphy’s Law (the real one) says: it’s impossible to make anything idiotproof because idiots are so ingenious. Or to put it another way, you make it idiot-proof and then they make a better idiot. This seems to be the case with both the items I repaired this month. In each case, the user (or one of their family members) managed to break it by doing something you’d think it would be designed to cope with. A while ago, a customer picking up her PC from my workshop noticed a few of my electronic bits and bobs lying around. She asked me if I knew anything about blood glucose monitoring devices. I immediately responded that since customers bring them in all the time, I was an expert at repairing them, and I knew them inside and out. Actually, sorry, that’s a lie. What I really said was no. While I had seen a few from afar, I had never played with them to see what made them tick. I decided to gloss over this technicality, though, and instead asked what the problem was. She said that as a diabetic, she 76 Silicon Chip needed such a machine to check her blood sugar levels. While her older, basic model still worked fine, she had shelled out a considerable amount of cash on a new, more sophisticated version, which she couldn’t get to work correctly. Perhaps I could have a look at it and see what I could do. Well, you know me, I had to at least have a go... When she brought it in, I was a little shocked at what she reportedly paid for the monitor. Though it looked like a quality, well-made unit, and came in a very nice travel case, there just wasn’t that much to it to justify the huge price tag. Having said that, if it worked as intended, it would be an ideal tool for managing her diabetes. The blood sugar monitor is a small, hand-held unit about the size of a pocket watch, with a Australia’s electronics magazine large, clear liquid-crystal display taking up most of the front face. On the top edge of the case is a receptacle for removable test strips. On the right-hand side of the case is a small sculpted gap, which looks like a socket for some kind of expansion module, and on the bottom edge is a mini USB port. That’s pretty much it; there are no switches or any other features to complicate things. This unit can connect via Bluetooth to a smartphone (or Bluetoothequipped laptop/PC), or to a PC via the USB socket. The smartphone app siliconchip.com.au Items Covered This Month • • • Two faulty Blood sugar monitors Olympus camera with a smashed viewfinder iPhone 5S battery replacement *Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz and the downloadable software for the computer (both accessible via a QR code included in the package) do pretty much the same thing, ie, save a record of all readings gathered by the device and present it in a graphical format. This enables the user to track their blood sugars, to see at-a-glance what’s happening, making things a bit easier to manage. It is a clever little device. But it didn’t work, and as it was purchased over a year ago, it was out of warranty. Most of these monitors operate in much the same way. The test strips look like a small rectangle of plasticcoated PCB material with exposed contacts at one end and a sensor track running down the middle. One is inserted into the slot at the top of the device and this action powers the machine on. A drop of blood from a pricked finger is presented to the tip of the test strip, and this is drawn down the centre track by capillary action. After a short countdown, a blood sugar reading is shown on the display. Usually, the monitor loses this information when the strip is removed and the device powers off, though with this model that data can be shared to a phone or PC. A lucrative business model Some of these machines can read both glucose and ketones levels. As these tests use different test strips, there has to be a way of telling the machine which strip is being used. The way they accomplish this is by plugging in a module, which looks very much like a USB dongle for a wireless keyboard or mouse, into that PCB socket I mentioned above. When a customer buys a container of test strips, a module is included siliconchip.com.au that is designed to work only with that particular monitor and set of strips. This is how the machine knows what it is measuring, and in this way, the manufacturer can guarantee reasonable accuracy. Each batch of strips and the module carry a unique identification number, and as long as these all match, the monitor readings will be as accurate as a home-use machine can get. So you can use one strip and module to measure blood glucose, then swap the module and the strip and test for ketones. Mind you, quality test strips aren’t cheap. I get the feeling that manufacturers of blood monitors took a leaf from the inkjet printer manufacturers’ playbook; they must make most of their money from sales of the consumables. And just like an inkjet printer, you can’t use test strips or modules from company A in the monitor made by company B. Clearly, there is big money to be made in health products, and all power to the people who design and market this stuff. But diabetics (here in New Zealand, at least) are offered little to no government subsidies for medical appointments, or any of the kit they need. It seems rather unfortunate that they charge as much as they do. But regardless of cost, no device is any good if it doesn’t work. In this case, the customer reported that it powered on when a test strip was inserted, but did not detect the strip module. The monitor was not detected when plugged into a PC via the USB cable either. I suspected that these two problems would have the same cause. The first thing I did was check the battery. There have been many times I’ve swapped cells out of a unit, to check whether it just needed a fresh battery, only to find that the cells I put in were already dead! Convenient though this solution may have been, both of the CR2032type lithium batteries (20mm diame- ter, 3.2mm thick) measured a healthy 3.1V on my analog multimeter; more than enough to fire it up. Opening it up was easy enough; a couple of tiny screws hidden beneath rubber ‘feet’ hold one end of the back cover while a clip arrangement holds the other. Once open, I could see a potential problem straight away. Of the four pins for the removable test-strip module, which is simply a set of exposed pins, two were bent. With the module in place, these pins weren’t making contact. The alignment of the module depends on how it is inserted into the cavity in the side of the case. Like a USB connector, it can only go one way. But given the lack of an actual socket frame or guide the module should line up with, it is easy to insert it cock-eyed. It looked to me that this is what happened. If it were forced in the wrong way around, that would explain the bent pins and lack of function. You’d think the manufacturer would have considered that and offered some protection against such a simple mistake ‘bricking’ the device. Luckily, straightening the pins was no real problem. I just had to be super-careful not to bend them too many times; this type of material is easily work-hardened, and it will break if pushed too far. I prefer to use tweezers for this sort of job because they prevent me from exerting too much pressure on the metal. I try to flex the pins only far enough to line them back up, and take great care not to overshoot and have to bend them back the other way. That is a sure-fire way to snap something off. This was a simple straightening job, and when finished, I immediately plugged in the module and made sure everything worked before buttoning it back up again. When I described what I found to the client, she recalled her teenage son had assembled the monitor when she first got it, and it was most likely Servicing Stories Wanted Do you have any good servicing stories that you would like to share in The Serviceman column in SILICON CHIP? If so, why not send those stories in to us? In doesn’t matter what the story is about as long as it’s in some way related to the electronics or electrical industries, to computers or even to car electronics. We pay for all contributions published but please note that your material must be original. Send your contribution by email to: editor<at>siliconchip.com.au Please be sure to include your full name and address details. Australia’s electronics magazine December 2019  77 he who had first inserted the test-strip module incorrectly. It was relatively simple to download the app into her phone, and I installed the PC program and drivers from the links provided, so I could check that the machines all talked to each other. To my knowledge, she is still using it and has reported no further problems. Repairs always come in twos I’m no stranger to odd coincidences. Back when I was a poor apprentice, my tooth broke. Later that day, I discovered enough money to cover the bill to fix it in a jacket pocket I hadn’t worn for years! Other times, I’ve thought of clients I haven’t heard of for years, then they call the next day, wanting work done. I’m busy figuring out how to capture and bottle this phenomenon and when I do, you’ll find me kicking back on Easy Street! So, not a week after that last repair, another client asked me about fixing a water-damaged blood sugar monitor. I thought it strange I’d never fixed one before and now, within a week, I have two coming through the workshop. This monitor was a very basic model, slightly older than the previous one, with fewer features and predominantly used for measuring ketones in the blood. This is useful for those on a socalled ketogenic diet – a high-fat, low carb diet which is used to get the body to burn ketones for energy instead of carbohydrates. The things we learn as servicemen! In order to know if the diet is working, many people turn to electronic blood monitors that can give reasonably accurate readings of blood ketone levels. If these numbers are maintained, fat loss (and the weight-loss that goes with it) is the typical result. This customer was standing near the kitchen sink with their monitor and had accidentally dropped it into the dishwater, whereupon it immediately ceased working. Despite putting it straight into the hot-water cupboard and leaving it for the past month, it still didn’t work. Liquid-damaged electronics are tough to diagnose. Sometimes everything starts working again after they dry out; other times, the device remains dead forever, regardless of whether a bag of rice, a hair-dryer or some other method is used to dry it 78 Silicon Chip out. Two identical devices could be submerged in the same circumstances with different outcomes. I typically explain this to the client and let them make the call as to how we deal with it. Given that you can pick up very cheap blood monitors out of China, it makes no sense to throw a whole lot of money at repairing an older, faulty one. So we have to decide how much effort (and money) it’s worth expending on a repair before we pull the plug and chuck it in favour of a new one. The customer had a new box of 100 test strips made specifically for this device, so it made sense to put a nominal amount of cash into at least trying to repairing it. Another easy fix Opening it was very similar to the last monitor, except this model used four small screws to hold the cover on. Once the back was off, I took the board out and checked under a microscope for obvious signs of water ingress. Though this was a relatively inexpensive model, they sure packed a lot onto the PCB. It was made with almost all surface-mounted components on a double-sided circuit board. Water under any of these components could cause it to malfunction, and getting any residue out could be a major headache. But it was surprisingly dry inside, and I couldn’t see any evidence of water ingress. So why didn’t it work? I started at the beginning, or at least the electrical beginning, with the contacts at the top where the test strip connects. On closer inspection, these looked very oxidised and patchy. While they appeared to be gold-coated, I guessed the actual gold content is a little lower than contacts in a higherquality monitor. Whatever other compounds were mixed in with it had tarnished. I used isopropyl alcohol and a light rub with my fibreglass-bristled cleaning pen to bring them back to the gold standard. I also checked the module pins – the module was still in place, and these too had a look of intermittency about them. Cleaning that was a little tricky, especially the contacts inside the module, but a few strips of alcohol-soaked tissue flossed carefully among the various pins and contacts had them looking better. Australia’s electronics magazine I installed new cells and broke out a fresh test strip. This time when I put it in, the display powered up. It looked a little blotchy, but it worked and displayed legible characters, so that was a lot more than what it was doing before. I pricked my finger and fed the test strip; apparently, I wasn’t in “ketosis”, but I didn’t expect to be, so the reading was most likely accurate. To be thorough, I removed the cells and module and put everything in a bag of rice in the airing cupboard for a week, in the hope of leeching any remaining moisture out of the parts before returning it to the customer. As far as I know, he is still using it, working his way through the test strips he has left. If he still wants a new monitor after that, he won’t feel so bad about wasting the money spent on strips. Olympus camera smashed viewfinder B. W., of Sydney, NSW, had that dreaded moment where he accidentally dropped the bag containing some delicate electronics and heard a nasty crunch. Luckily, he had a piece of donor equipment and the patient survived the operation... It all started when I was hurrying along a Melbourne train platform with my lovely old Olympus C8080W in its siliconchip.com.au carry bag, the strap over my shoulder. The strap slipped off my shoulder and down it went onto the pavement. My first thought was that the glass in the wide-angle lens could have smashed on impact. On opening the bag, I could see that the digital viewfinder glass was cracked and the LCD screen behind it was showing tell-tale black areas where the liquid crystal had leaked out. While the bag is padded to handle short drops and other impacts, unfortunately, the lens cap had been pressed into the viewfinder, resulting in this damage. The camera has a second internal viewfinder but while this worked in playback mode, it no longer worked when I tried to take a photo. Perhaps the damage was shorting something out. Regardless, I would have to fix the smashed screen. I had another identical camera which no longer worked but the screen was intact, so I decided that this would become a donor. My pal Dick from the Yahoo Olympus Camera Group sent me a pictorial breakdown PDF of the camera internals so that I could see the disassembly steps required. I would need a set of tiny screwdrivers, tweezers, close-up eyeglasses, good lighting and a cautious approach to succeed. I started to take the camera apart and it all went well. Finally, I had the LCD screen out of the articulated holder but still connected to the feeder PCB hiding just inside the holder, with two flat ribbon cables still firmly attached. The next step was the most delicate; if I made a mistake by forcing any of these fragile and tiny components, the whole repair and the future of this camera could be in jeopardy. The ribbon cables were sensibly attached to connectors on the partly hidden PCB, still inside the articulated carrier. I gently nudged them as best I could but they would not budge and there was nothing obvious to pull or push on the sockets to remove the cables. I had to turn to the internet for answers. I found the following YouTube video from a German guy who was doing just what I needed to do, on the same model of camera. His lighting was poor and the camera angle was not great but just once, he showed a pull of a locking black bar across the top of the socket and the ribbon cable then came free! See: http://youtu.be/ uyCVRY9Z1h0 So that was it! Now with confidence and armed with a dentist’s hooked tool, I ventured into the hidden cave of the PCB and hey presto, the socket opened up, allowing the ribbons to slide out and the donor ones to go into place with ease. I then re-locked the ribbons into the sockets, re-assembled the camera, inserted the battery and switched it on. Hooray, the viewfinder was operational! I then just had to clean the display, re-fit the protective glass panel and then make some changes to my carry case so this sort of damage will never happen again. the back and sides of the phone. It all felt “squishy”, so I suspected that the battery had become swollen and was pushing the screen out. My wife had also remarked that the battery was tending to run down quickly, which strengthened the swollen battery hypothesis. A swollen lithium-ion battery is a fire risk, so until a new battery could be fitted, I found a large Pyrex bowl that we could put the phone in while it charged, to prevent it from igniting anything else if it caught fire. The Apple store charges $119 to replace the battery in this model, which is more than the phone is worth, and it probably couldn’t be done while we waited. There are various phone repair stalls in arcades and shopping centres, and they charge about $35 to replace an iPhone battery, but I decided to have a go at it myself first. Despite some misgivings, I bought a new battery from eBay which was advertised as “brand new genuine original”. It cost just under $18 delivered, including a full set of tools and the allimportant adhesive strips, and I had it in less than two days. I was pleasantly surprised at the quality of what I received. The iFixIt.com guide for iPhone 5S battery replacement estimates it will take between 30 minutes and an hour. It took me closer to two hours, but that’s because I read every single comment that individual fixers had made iPhone 5S battery replacement A. P., of Concord, NSW obviously loves a challenge because he had the option to pay someone else a small fee to fix his wife’s phone but decided to do it himself anyway. Luckily, it worked out well in the end... My wife recently told me that her iPhone 5S was showing “rainbow colours” wherever her finger touched the screen. I took the phone out of its protective case and observed that the bottom edge of the screen was pushed slightly out of the aluminium shell that forms siliconchip.com.au Australia’s electronics magazine December 2019  79 on every single step; I’m glad I did, as they almost certainly saved me from breaking something. The first step when the battery is swollen is to discharge the phone’s battery to no more than 25%, to minimise the risk of the battery catching fire if ruptured. The phone was at 83% charge when I started, so I set the screen to full brightness, turned on the torch function, and set AutoLock to “Never”. I used the time while the phone battery was discharging to read through some of the steps of the repair and the associated comments, but after half an hour and with the battery still at over 50% charge, I became impatient and powered the phone down, ready for the dismantling process. The iPhone 5S case consists of a one-piece aluminium tray which forms the back and edges of the phone. The front panel squeezes into the tray and consists of the display, its narrow plastic bezel, and metal clips which grip the inside edges of the tray. The tray holds most of the electronics and hardware of the phone, including the battery. There are some flat cables near the top of the phone that connect the display and front camera and sensors to the motherboard. There is almost no slack in these cables, but the display can be pivoted up 90° with these cables still connected, giving pretty good access to the interior of the phone. There is one other flat cable, near the bottom of the phone, that connects the home button/Touch ID sensor to the motherboard. There is enough slack in this cable to allow the bottom of the display to be lifted a couple of centimetres away from the tray, which gives sufficient access to disconnect the cable from the motherboard. To start with, I removed the two pentalobe screws at the bottom, on either side of the lightning socket. The home button cable is particularly prone to being torn in this model because the front panel is meant to be quite a tight fit in the tray and can come away suddenly. If you damage the cable, you have to replace the home button, but only the original home button is “keyed” to the motherboard so you’ll lose the Touch ID feature. As I started pulling the two halves apart, I noticed that the display was separating from the metal clips. The iFixIt crowd-advice for this sit80 Silicon Chip uation is to ease the metal clips out of the tray using two plastic tools shaped like guitar picks. These were supplied with the new battery, and I found that by using a combination of fingernails to do the pulling and inserting the picks into the gaps to prevent them from closing up, I was able to ease the bottom of the front panel up out of the tray without too much trouble. The next step was to remove the clip that secures the home button cable’s plug in its socket on the motherboard. Having removed the cable, I discarded the clip as I realised that it would be awkward and risky to reinstall it. I read comments from those who had done likewise and found that the cable nevertheless remained secure. I then popped the home button cable off the motherboard using the corner of a spudger and was able to lift up the bottom of the front panel, with the remaining flat cables at the top of the phone bending like a hinge. The battery was now fully exposed, and I could both see and feel its swelling. The new battery, by way of comparison, was perfectly rectilinear. At this point, iFixIt guides you to remove the display, touchscreen and camera/sensor cables from the motherboard, thereby separating the front panel from the phone. This would have required dealing with another four tiny screws in three different sizes (1.2mm, 1.3mm and 1.7mm) that must all be put back in the correct holes during reassembly, or else risking permanent damage to the motherboard. I felt that I had good enough access to remove and replace the battery without bothering to disconnect these cables, so I skipped ahead to the battery removal. The battery connector is secured by a screwed-down clip. This was easy to remove, and I then used a spudger to pop the battery connector off the motherboard. Even this apparently easy step has a gotcha: it is difficult to see whether you have inserted the spudger between the battery connector and its socket, or between the socket and the motherboard. Prying too hard when the spudger is under the socket is liable to damage the motherboard. The next step is to remove the old battery, without using sharp metal tools that could puncture it. The battery is secured to the tray by a couple Australia’s electronics magazine of double-sided adhesive strips. These strips emerge from the lower end of the battery and join to a pull-tab that is usually tucked into the space at the lower edge of the battery. You pull slowly on the tab and the adhesive strip narrows and pulls away from the space between the battery and the tray. To make removal of the adhesive strips in this phone easier, iFixIt suggests putting the phone on something warm to soften them first. I microwaved a damp face flannel in a plastic bag and laid the phone on top, then teased the pull-tab out from the gap at the lower end of the battery. There is a small hole in the tab, and the tiny Philips head screwdriver that came with the battery let me pull it out far enough to be grasped in my fingers. Then I pulled gently on the tab, just enough to see the two white adhesive strips start to come out from under the battery. At this point, I snipped the tab in two using nail scissors so that there was a separate tab for each of the two strips – this lets you deal with each strip separately. Next, I pulled a little bit more firmly on one of the tabs. The trick is to pull firmly and constantly, but to be patient. It also helps to continually work your fingers along the strip towards the battery as the strip stretches, as this minimises the chance of the strip breaking. In my case, both strips snapped before they were completely out, so I was left with the unenviable prospect of levering out the battery while avoiding bending it too much lest it rupture and catch fire. To do this, I used a plastic spudger and used the same principle of firm, constant pressure and patience. By applying not quite enough force to perceptibly move the battery, and waiting, the battery came free without being deformed. Once the battery was out, I was able to clean up the remains of the adhesive strips. The replacement strips have blue protective film on the side that is to be installed facing the tray, and pink film on the side that faces the battery. After sticking the new battery into the case, reassembly was straightforward and the front panel now fit precisely. The phone works fine with its new battery, and the rainbow colours surrounding fingers touching the screen are gone. SC siliconchip.com.au Tech for Xmas Build It Yourself Electronics Centres® 499 $ SAVE $100 K 8400 Gift a gadget this festive season! Sale ends December 31st PLA colour filament 1kg roll: $39.95 139 $ C 9021A Core I3 Desktop 3D Printer DIY Kit Add 3D printing to your workbench to produce working prototypes, ‘one-offs’ & finished designs downloadable from the internet. From printing your own gaming pieces to cosplay parts & fixes for broken parts, this printer adds versatility to any workbench. Filament roll holder to suit K 8403 $17.95. Why pay $300 or more? Excellent quality sound reproduction & noise cancelling. Features: • 200x200x200 build volume• PLA filament • Pre-terminated cables for easy construction • Heated print bed • Assembly time ≈3 hours. • Includes power supply SAVE $54 Amazing sound. You be the judge - demo a pair in store! Super Quiet Noise Cancelling Bluetooth® Headphones 225 $ SAVE $14 T 2120 60 $ M 8199A No outside interference with world class noise reduction technology. Designed & engineered in Silicon Valley USA. • A must have for any regular traveller! • Superb active noise cancelling • Bluetooth wireless • 12hrs of listening time. • USB rechargeable (includes cable) • Carry pouch. N 0706A 15W 79.95 $ N 0704A 10W 59.95 $ 240V power from a lithium battery! Carry 240V Power Anywhere! This portable solar generator is fitted with 42,000mAh battery bank & 240V mains inverter. Allowing you cable free power for both AC and DC appliances anywhere! Plus 2.1mm DC power & USB charging. N 0040E 40W solar panel to suit $85. 39.95 $ Cut, Polish, Grind, Sand & Carve. This workbench essential is just the shot for electronics projects, crafts, hobbies and odd jobs around the house! Powerful 130W motor with variable speed between 8000 and 33000 RPM. Included is a 172pc accessory kit of grinding wheels, drills, cutters, sanding discs, polishing pads and more! Stows away in a hard plastic carry case. SAVE $9.95 30 $ No more eye strain! Keep vehicle batteries in top condition These compact monocrystalline solar panels are designed for keeping your vehicle batteries topped up when parked. Easy croc clip or car accessory plug connection. Can even be permanently installed outdoors. 10W: 377L x 212W x 17D mm. 15W: 40L x 343W x 17Dmm. D 2203 SAVE 15% GREAT FOR: • Motorbikes • Caravans • Boats • Vintage cars • Jet Skis • Mowers & more! K 8391 Orange K 8392 Green K 8393 Yellow K 8394 Purple New PLA Filament Colours Print the rainbow with 1kg reels of orange, green, yellow and purple now available. X 0432 Get a crisp close up view 5x magnifier with LED backlight. Great for reading fine print, sewing etc. USB rechargeable. Includes carry case. See last page for store locations or visit altronics.com.au 10 $ Mini Car Phone Holder • Suits phones up to 85mm wide• Grips securely to your air vent Sale pricing ends December 31st 2019. Power Up Your Holidays! SAVE $50 Suits hundreds of laptop models! 70 $ 199 $135 $ SAVE $19 M 8012A 400VA M 8010A 150VA Power mains appliances on the road! • Delivers pure AC power from your car battery • Ideal for tricky loads, such as laptops, & game consoles • USB charging output • 12V input • M 8010A 300W surge rated, 170x108x60mm • M 8012A 800W surge rated, 200Lx108Wx60Hmm 239 $ Multi-Voltage Replacement Laptop Supply N 1130F 130W Folding Solar Panel For Remote Power Lost your laptop power supply? Or need an extra one for the office? This unit includes mains lead and 10 tips to suit popular models of laptop. Voltage output is set automatically. 5-24V <at> 90W max. Includes jump starter & air compressor Includes regulator, 5m battery cable & carry bag. SAVE $60 M 8990A 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). Works with Google Home & Echo SAVE $40 129 $ M 8198 SAVE 26% P 8148 39.95 $ Inflate a tyre. Start a flat battery. Travel Power Great for the 4WD/car enthusiast. Features a 16800mAh battery bank plus emergency compressor to top up tyres (max 8 mins run time). Provides 600A peak battery cranking output. 12/16/19V & USB output for powering devices. 22 SAVE 32% 44 $ Automate your Christmas tree lights! Charge EIGHT USB devices at once! Switch any connected appliance on or off remotely from anywhere in the world. Set schedules, monitor and control via your phone. Got a family full of devices? This handy charger outputs up to 12A or charging current to keep all your tablets and phones juiced up! Includes power cord. M 8881 $ Home QC3.0 Wall Charger M 8863 Charge QC 3.0 devices up to 4x faster than conventional USB chargers. 3A output. Compact case doesn’t block outlets on your powerboard. SAVE 22% D 0505A SAVE 25% 19 Charge up to 3 devices at once! 30 $ $ 1A 4Ah SAVE 25% D 0515 25 $ SAVE 16% A 0309B 50 Stay charged up on the go - no cables required. Stay powered up on your travels! • Charges 4 devices at once • Australian, US, UK and European outlets • 5V 4.1A output • 100-240V AC • Travel case. $ • Slim 10,000mAH design • QI wireless charging pad • Works with iPhone and Android • Includes USB cable. D 0507A 2A 8Ah Super Slim Battery Banks Emergency pocket power supply for your phone, tablet or drone. Slimline aluminium design with carry pouch. Micro USB recharge (cable included). Save on summer storm protection! 650VA Backup UPS & Power Protector Provides power backup when mains fails, plus added protection for surges and spikes on power, phone & data lines. Backup time up of 40 mins depending on load. Includes monitoring software. 2 year warranty. Protect your work bench appliances! SAVE $14 135 $ D 0881 UPS Backup for 12V DC Appliances A compact 12V DC 18W UPS unit for providing backup power to all kinds of DC powered equipment. Great for routers, NAS, telephone & comms systems. Backup power for NBN routers! SAVE $12 D 0875 80 $ 750VA UPS Power Protection Board This quality UPS unit will prevent appliance damage caused by Top level power fluctuations, power PLUS keep power protection on during a blackout! Also protects phone lines. 2 year warranty. altronics.com.au » 24/7 ordering » In-store order pick up. » Fast delivery. D 0873 SAVE $16 159 $ Festive gifts & handy gadgets for all! Bluetooth® BBQ SAVE 15% Temperature $ Monitor X 4201 5 Dioptre 59 X 7015 Love your slow cooked meats? Cook to perfection with the EasyBBQ dual probe monitor. All while you kick back and enjoy a coldie! Android or NEW! iOS compatible. 0-300°C range. Requires 2xAAA batteries (S4904). X 4200 3 Dioptre SAVE $34 Top gift idea for makers! 145 $ 30W Lithium ‘Go Anywhere’ Soldering Iron 45 minute run time. 600°C max. Ideal for occasional soldering jobs or light duty repairs and field servicing. Recharge by USB power adaptor in your car or at home - or USB battery bank. Includes replaceable 18650 battery. *Phone for illustration purposes. D 0504A No more eye strain! INCLUDES ACCESSORY PACK: • 3 tips: conical, hot knife/3D print finishing tool, hot air • Micro USB cable • Solder container & 1m of solder • Tip sponge. 2 in 1 Battery Bank Compact The perfect every day accessory for the handbag. • Dual mirror (with magnified view) • LED ring light for a clear view • 3000mAH battery bank for recharging • Includes carry case and charging cable. 95 $ T 2694A Why spend $300 on a Maggy-Lamp®? Ultra-bright long life LED for fantastic clarity (plus no need to change a globe - EVER!). Let “gadget” be your eyes. Identify those impossible to read miniature parts without straining your eyes. Great for collectors, model makers, jewellers etc. 130mm lens. Suits desks up to 60mm thickness. SAVE 22% 39 $ SAVE 10% 40 X 7026 $ D 2207 SAVE 35% 25 Phone Holder with Wireless Charging $ SAVE $10 39 $ Wireless Weather Station Simply place your phone in the holder to keep it topped up whilst you’re driving! Convenient windscreen or air vent mounting. Great for Uber drivers or road reps. Includes USB A-C cable. • Indoor/outdoor temperature • Humidity & air pressure • Weather forecast, moon phase, time & date. • Requires 2xAA (S4955B) & 2xAAA (S4949B) batteries. SAVE $20 SAVE $15 59 $ X 0225 X 3260 X 4003A SAVE $14 The ultimate camping, fishing, anything light! Provides 5 hours use from a high performance lithium battery. Folds flat for easy storage and recharges from any USB mains (M 8861) or car charger (M 8628). 10W, 1000 lumens. 55 $ Home Blood Pressure Monitor A must have for anyone over 50 years old! Save on doctors visits. This handy meter records your measurements so you can monitor changes over time. Also includes an irregular heartbeat monitor. Stores readings for 2 people. Requires 4xAA batteries (S 4955B $3.95). Easy Camp Site LED Lighting Strip Great for setting up temporary lighting at campsites. • Yellow light reduces insects. • Secures to tent poles with reusable ties • 12V powered (car adaptor included). • Great work light or dim it down for reading. 5m roll. Secure your place for less these holidays. REDUCED FROM $899 IS PRICE! 20 SYSTEMS ONLY AT TH Affordable 4 Megapixel CCTV Surveillance System. 499 NEW! $ 119 $ S 9900H 4 Domes SAVE $400 Why settle for just HD? This system features 2K detail and clarity. Simple to install with instructions supplied. Cameras can be remote viewed on iOS/Android. Each pack includes: • HD digital video recorder • Pro grade 4MP resolution weatherproof cameras • 20m connection leads • Power supply • HARD DRIVES TO SUIT: 1TB $110 (D 5514), 2TB $155 (D 5516). S 9018 NEW! TP-Link® Wi-Fi Indoor Camera 89.95 Crystal clear wide angle 1080p vision with instant alerts of movement, plus two way audio. Excellent night vision performance and easy viewing via the Kasa home app. See last page for store locations or visit altronics.com.au S 9017 $ TP-Link Wi-Fi Pan/Tilt Indoor Camera ® Get the full picture with 360° horizontal and 118° vertical motorised viewing. Kasa app allows easy swipe pan/tilt movements. Provides 1080p full HD video with object tracking mode and night vision. Sale pricing ends December 31st 2019. 1. Learn electronics. 2. Have fun! 48.95 Ages 8+ Tobbie II Robot Kit K 1148 A great STEM robot for the classroom! Tobbie is back and he’s had an upgrade! Now powered by the popular BBC micro:bit board, this new version has unlimited scope for self programming. Front screen displays text & symbols. Great for teaching kids coding. Requires Learn 4xAAA batteries (S 4949B $9.95) coding! and BBC micro:bit board. Ages 8+ K 1152 Scurrying Hedgehog Kit 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! Features light up eyes and motorised feet. Assembles in <2 hours with no special tools required. Requires 4 x AAA batteries (S 4949B $9.95). 59.95 K 1150 $ Tobbie The Smart Robot Kit A six legged robot kit designed to avoid objects or follow you around the room. Easy to build. Interactive AI develops its own emotions and gestures. Requires 4 x AAA batteries (S 4949B $9.95). Have fun! or $89.95 with BBC micro:bit starter pack (Z 6440). SAVE $5.50 Ages 8+ SAVE 25% SAVE 23% 19.95 $ 45 20 $ $ K 1144 K 1095 K 1132 SAVE 13% Build it 14 ways! K 1113 SAVE 22% 30 $ 14 Solar Kits In One! 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+ Build it 6 ways! Mini Solar Bug Kit Features 51 parts to build up into a solar powered bug which struts about when you place it in the sun. Ages 8+ 19 $ K 1139 Solar Powered Rover Kit Solar Recycler Kit Uses soft drink cans & old CDs to create 6 fun solar powered designs. No soldering or batteries. Ages 8+ K 1135 K 2208 130 in 1 Electronics Learning Lab 99 25 $ 39.95 $ 20 4 in 1 Robotics Kit Assemble 4 robot designs which teach kids about geared movement in a fun way! Requires 1xAA battery. No soldering required. Ages 7+ Air Powered Buggy Kit 12 In 1 Solar & Hydraulic Kit 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+ 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). 8+ Sale Ends December 31st 2019 Build It Yourself Electronics Centres Western Australia » Perth: 174 Roe St » Balcatta: 7/58 Erindale Rd » Cannington: 5/1326 Albany Hwy » Midland: 1/212 Gt Eastern Hwy » Myaree: 5A/116 N Lake Rd Phone: 1300 797 007 Fax: 1300 789 777 Mail Orders: mailorder<at>altronics.com.au Victoria 08 9428 2188 08 9428 2167 08 9428 2168 08 9428 2169 08 9428 2170 » Springvale: 891 Princes Hwy » Airport West: 5 Dromana Ave Find a local reseller at: altronics.com.au/resellers 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. Queensland 03 9549 2188 03 9549 2121 New South Wales » Auburn: 15 Short St Build it 12 ways! K 1149 $ $ A comprehensive learning lab with many hours of building. Build a radio, broadcast station, organ, kitchen timer, logic circuits & more. Requires 6xAA batteries (S 4906 lithium 2pk $4.95ea). Ages 10+ SAVE 23% SAVE 22% K 1126 SAVE $40 Build it 3 ways! 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 (S 9455B 4pk $3.95). Build this fun 6 wheel all terrain vehicle modelled on famous NASA designs. No soldering or batteries required! Ages 8+ Build it 4 ways! Lab kits to suit any budget in store! 3 In 1 All-Terrain Robot Kit » Virginia: 1870 Sandgate Rd 07 3441 2810 South Australia » Prospect: 316 Main Nth Rd 08 8164 3466 02 8748 5388 © Altronics 2019. E&OE. Prices stated herein are only valid until date shown or until stocks run out. Prices include GST and exclude freight and insurance. See latest catalogue for freight rates. B 0091 49.95 $ $ PRODUCT SHOWCASE Rohde & Schwarz ’Scopes: deep memory matters Rohde & Schwarz RTA4000 oscilloscopes support up to 1 Gsample of memory per channel. That’s important, as R&S explain: Deep memory in a digital oscilloscope will allow you to capture simultaneously both slow and fast signals with sufficient resolution between sample points to see signal details. You should have enough resolution to ensure that you don’t miss important signal events. Rohde & Schwarz digital oscilloscopes have enough deep memory to capture long waveforms at a high resolution and sample rate so you can be confident that you are not missing signal anomalies or important events. But remember, as your oscilloscope runs out of memory the oscilloscope automatically begins reducing sample rate so deep memory really matters. Deep memory also helps when cause and effect are well separated. Contact: Rohde & Schwarz (Aust) Pty Ltd Unit 2, 75 Epping Rd, Lane Cove NSW 2113 Tel: (02) 8874 5188 Web: www.rohde-schwarz.com/oscilloscopes Plastic and Electronic Components from Hi-Q Hi-Q Electronics Ltd, trading as Hi-Q Components, is a one-stop shop for that last-minute design phase. Hi-Q will provide solutions from stock for enclosing and mounting your printed circuit board. They also stock a lot of other component solutions to complete your project including, cable glands, switches, connectors, rubber bumpers and feet, buzzers, terminal blocks, cooling fans, LED assemblies, nylon screws, nuts, spacers and washers. If you need to produce PCB prototypes in-house and in a hurry, the LPKF Protomat D104 from Embedded Logic Solutions could be the solution! The LPKF Protomat offers a focus size of just 15µm, and can achieve minimum PCB track widths of 50μm and spaces of 15μm. Other features include an integrated vacuum table and 20 tool change positions, full automatic operation, camera-controlled fiducial recognition and milling width monitoring and automatic copper and material thickness measurement. Contact: Embedded Logic Solutions Pty Ltd 5/23 Hunt St, North Parramatta, NSW 2151 Tel: (02) 9687 1880 Fax: (02) 9687 1881 Website: www.emlogic.com.au New EC Series Compact Emergency Stop Contact: Hi-Q Components 6C Douglas Alexander Pde, Albany NZ 0632 Tel: (+64) 9 415 3333 Fax: (+64) 9 415 8686 Website: www.hiq.co.nz PCB Global says “take a look into the future” PCB Global is a dedicated, quick turn, high technology PCB supplier that promises to exceed your expectations in respect to quality, delivery and price – in an instant, professional online experience. Their prototype service can turn 2-layer boards around in as little as two days (with express delivery). Or they can produce up to 20-layer prototype boards in seven days. Quotes and orders can be processed 24 hours a day, 7 days a week and 365 days a year on an easy-to-follow online portal, with automated instant quotes and automated order proContact: cessing. In addi- PCB Global tion to PCBs, they offer custom aluminium ex- Unit 220, 14 Lexington Drive, trusion, CNC-machined stainless steel, custom Norwest Business Park,Bella Vista, NSW 2153 metalwork and a variety of cable assemblies Tel: (02) 9672 6879 Fax: (02) 9629 6302 – ribbon, SMA and general cabling. Web: www.pcbglobal.com siliconchip.com.au New Generation PCB Prototyping Machines Australia’s electronics magazine Control Devices is the official APEM distributor for Australia and New Zealand and is pleased to promote the new EC series, the first compact emergency stop switch, with an integrated connector or solder lug terminals for easy mounting. • Limited under-panel depth and comes with a 22mm diameter bushing. • Ergonomically designed and vibration resistant, ideally suited for material handling, AGVs and off-road vehicles. • Immediate cable and switch connection will make switch mounting easier and safe. • Currently the only estop on the market with a connector terminal. Contact: Control Devices Unit 17, 69 O’Riordan St Alexandria NSW 2015 Tel: (02) 9330 1700 Web: www.controldevices.com.au December 2019  85 High Power Linear Bench Supply Part 3 We have described how our new 8A Linear Bench Supply works and how to assemble its main PCB control module over the last two issues. Now it’s time to finish it off. That involves cutting some holes in the case, mounting the components inside, attaching the front panel controls, wiring it up and doing the final calibration and testing. W e chose to put the Bench Supply in a Jaycar HB5556 instrument case because it’s just big enough to fit everything without making it too large or heavy; it’s reasonably priced and easy to get, easy to work and it has plenty of ventilation for the required cooling air. The following instructions assume you are using that case. If using a different case, make sure that all the parts will fit inside and that nothing will foul anything else; if it’s substantially larger, you should be fine. You also need to ensure that it has adequate ventilation, especially in the top and bottom panels around where the heatsink will be mounted. Ambient air is sucked in through holes at the rear of the case, blown over the heatsink and exits through holes above and below the heatsink fins. Your case will need to have a similar arrangement. 86 Silicon Chip It also needs to be made of steel or aluminium, not only for strength but also so that all of its panels can be Earthed for safety. Any case that meets these requirements can be used, but you will have to vary the instructions regarding where to mount the components inside the case and on the front and rear panels, and adjust the cutout and wiring placements to suit. So without further ado, let’s get to finishing off the Bench Supply. Preparing the case Several holes need to be drilled and cut into the metal instrument case. The front panel hosts the panel meter, control potentiometers, output binding posts, over-current LED and load switch, by Tim Blythman Australia’s electronics magazine while the mains socket and fan cooling holes are on the rear panel. All six panels also have Earth screws to ensure safety. The bottom part of the case also needs to be drilled to mount the transformer, PCB and heatsink. The top and bottom panels are vented; the case is orientated with the vents at the rear, as this is where the fans and heatsink are mounted. It may help you to start by putting the case together, so you understand how all the parts fit, then mark where holes will be drilled in each panel while it is in place. Fig.8 shows the hole locations and sizes for the front and rear panels. We recommended in the article last month that you use the blank PCB and heatsink spacer to mark out the required hole locations in the base, as well as the hole for the transformer mounting bolt. Check now that these are in the right places. The case is made of aluminium, so it siliconchip.com.au Fig.8: use these diagrams to assist you in cutting and drilling the front and rear panels. Note they are 60% of life size, so to copy and use as a template you will need to enlarge them by 166.7%. Downloadable PDFs are at siliconchip.com.au is not hard to work. No holes need to be made in the case sides, but their internal ribs must be trimmed to allow all the components to fit. We recommend test-fitting all the parts before doing any drilling or cutting, to make sure it will all go together properly later. This is especially true if you are making any variations from our design. Rear panel preparation Even though the panels are not flat, they can be held in a vice by placing them between some scraps of timber. This will also help to prevent damage to the enamel finish. We opened up the large holes in the panels using a 3mm drill bit on a drill press, making numerous closely-spaced holes inside the outline. The holes were then joined with a hacksaw, after which the edges were brought to dimension and finished with a file. You may also There isn’t much mounted on the rear panel; just the switched, fused IEC mains input socket and the two cooling fans. The small screw head visible to the right of the mains socket is the main Earth point inside. siliconchip.com.au Australia’s electronics magazine December 2019  87 The front panel of the Bench Supply has two knobs to set voltage and current and a switch to connect or disconnect the load, along with the three output terminals. The red LED above the current knob indicates when thermal limiting is occurring. The LCD screen shows the actual and set voltages, actual current and current limit, plus the heatsink temperature. find a nibbler useful, if you have one that can handle 1mm thick aluminium. For the hacksaw cuts, we removed the blade from the hacksaw, threaded it through the pilot hole, reattach the blade to the hacksaw and then made the panel interior cuts. We suggest that you use a similar technique to make the cutout for the IEC socket. Mark its outline on the rear panel and then drill a series of small holes inside the perimeter. Keep the holes well inside the markings. Drill a larger hole (large enough for a hacksaw blade or other small metal saw) inside. Then use a hacksaw blade to cut towards the corners from the large hole in the centre. Take care that the sheet metal does not bend and break on the forward stroke. Once the cuts have reached the corners, the triangular shapes may be flexed along the drill holes, to break them off. Use a file to carefully bring the edges of the cut to their correct dimensions. Keep the mains socket nearby to test fit, as you do not want to take away too much metal. This could cause the receptacle to be not held securely by its tabs. Try fitting the socket at an angle to test the height and width independently. Once the dimensions are correct, gently run a file across any sharp edges of the opening to remove any burrs. Now is also a good time to drill a 3mm hole in the rear panel for the Earth connection. The location is not critical, but placing it near the receptacle will minimise the Earth wire length. Sand the inside of the panel until you have an area of exposed bare metal around 1cm in diameter around the hole. The aim is to make a good metal-tometal connection with the eyelet lug at 88 Silicon Chip the end of the Earth wire. You will also need to drill eight 3mm holes to mount the fans. Test fit the fans to check their locations as there is not much room around the fan guards, and they need a small amount of clearance to allow the filters to be clipped on and off. You may need to space the fan mounts so that they are not hard against each other. Two large holes are required so air can be drawn in by the fans. We traced out a circle using the inside of the fans as a template, but any circular object around 80mm across will be fine (or copy/print Fig.8 to use as a template). Check that the fan guards completely cover your marked hole before cutting it out. Use a similar technique to the IEC receptacle to open out the holes. Drill a series of small holes and then open up the panel with a hacksaw blade and finish by filing down the rough edges. You can now fit the mains socket. Orientate it so that the lead plugs in below the switch, allowing access to the switch from above. Now is also a good time to insert the fuse. While the 6A fuse chosen may seem excessive for a 500W transformer, this is the recommended rating for that transformer. Lower-rated fuses will blow due to inrush current when the unit is switched on. If you want to use a lower value fuse, it will need to be a slow-blow type. Front panel preparation The front panel is treated similarly to the back. Assuming you are using our Five-way Panel Meter, check that your LCD screen’s dimensions match our template and then transfer this to Australia’s electronics magazine the front panel. We have designed an acrylic bezel that suits the LCD on the Five-way Panel Meter, which hides any small inaccuracies in cutting the front panel around the Meter. You can place the bezel over the LCD to see if it matches the dimensions and if so, use it as a template to mark out the front panel. Otherwise, use the LCD dimensions or Fig.8 as your guide. If you have separate panel meters, check their specifications for recommended cutout dimensions, and plan how they should be laid out, leaving room for the binding posts, switch and potentiometers. Cut out the opening for the panel meter(s) using the same technique as for the mains socket. You’ll also need to drill the four 3mm mounting holes. You also need to drill two or three holes for the binding posts; three are required if you want an Earth post, which can come in handy from time to time. Otherwise, the supply outputs are ‘floating’. Check the diameter of the holes required for your posts and drill them with equal spacings. Ours were 9mm. Start these holes by using a punch to locate the centre of the hole and then by drilling with a smaller size to create a pilot hole. Finish with the recommended size drill bit to complete the hole. Similarly, drill a hole below the panel meter for the output on/off (load) switch. Typical panel-mount toggle switches require a 6.5mm hole, but again, it’s best to start with a smaller pilot hole and then enlarge it to the final size before deburring. Below the banana socket holes, add a 3mm hole for the front panel Earth. siliconchip.com.au As for the rear panel, sand the inside to remove the enamel for about 1cm around it. The two potentiometers require two holes each to mount; one for the shaft and a second to hold the locating lug so that the pot won’t rotate. Drill the two holes using the usual technique. Drill a hole for LED1 as well, taking into account the bezel diameter. If you wish to add our front panel artwork, you should do so now. The best way to get this is to download the PDF from the SILICON CHIP website, print it out and laminate it. Note that the front panel is wider than an A4 piece of paper is long, so it will look better printed on A3 so that no joins are needed. Alternatively, you can print on selfadhesive sheets (see siliconchip.com. au/Help/FrontPanels). Mounting the front panel components Solder a 20cm length of black 10Arated wire to the black binding post, and a 20cm length of red 10A-rated wire to one terminal of the output switch. A second 5cm length of red wire is then soldered between the other switch terminal and the red binding post. Insulate the solder joints with heatshrink tubing. Strip back the last 5mm of both free wires for connecting to CON1 on the main PCB. If adding an Earth binding post, attach a short length of 10A green/yellow wire stripped from mains flex or a mains cord, and crimp or solder an eyelet (ring) lug to the other end. It will attach to the front panel Earth screw later. The binding posts and output switch can now be secured using the supplied nuts and washers. Orientate the switch so that it makes the connection from the red binding post to CON1 + on the PCB when it’s down (the standard position for ‘on’ in Australia and New Zealand). Thread the potentiometer shafts through the panel from the back and locate the lugs into the smaller holes to stop the potentiometers from rotating. Secure at the front with mounting nuts and fit the knobs. We used spline shaft potentiometers, which allow the knobs to be attached at almost any angle. If you have D-shaft potentiometers, you may need to rotate the front part of the knob later so that the pointer sweeps over an appropriate range (these can usually be prised off with a knife). Now mount the rest of the front panel hardware. Fit the LCD bezel by threading a 12mm M3 machine screw through each corner, then feed the screws through the holes in the front panel. Secure with M3 nuts at the back of the panel. If your LCD has mounting holes which are too small to fit an M3 screw, these can be carefully enlarged with a 3mm drill bit, ideally in a drill press. Avoid inhaling the fibreglass dust which results. Five-way Panel Meter LCD can then be threaded over the back of the machine screws and held in place by four more nuts. Attach the IDC cable to the header, ensuring the marked pin 1 on the cable lines up with that on the PCB. Finish by pushing the LED with bezel through the hole you drilled for it earlier. Transformer and main PCB If you haven’t already marked out and drilled the required holes in the bottom of the case, use the populated PCB, heatsink spacer and transformer to determine where the holes need to go. All of these need to be drilled to 3mm and deburred, except for the transformer mounting bolt hole which will need to be larger. Measure the diameter of the supplied bolt; around 8mm should do. Before drilling those holes, it’s a good idea to slot the front and rear The main requirement for the SPST “LOAD” switch (mounted under the display) is that it must be capable of handling the whole output current – up to 8A DC. Practically, this means you’ll need a 10A DC switch – don’t be tempted to use one only rated for 10A AC – it’s not enough! siliconchip.com.au Australia’s electronics magazine panels into the case to make sure that the internal components will not foul anything mounted on either panel. Test fit the transformer and PCB according to the markings, to ensure that everything fits as expected, then drill the holes. You may need to remove the side panels as they are likely to conflict with the PCB and transformer mounting positions. You can test fit these later to confirm how they need to be trimmed. We needed to trim away some of the internal parts of both side panels on our prototypes, as the side panels protrude slightly into the case near their fastening holes and screws. Check that there are no collisions between the PCB, transformer and front and rear panel hardware. Keep in mind that the fans and their spacers will sit between the heatsink and the rear panel. You might also like to check that the transformer’s leads reach the mains plug receptacle and the bridge rectifier tabs on the PCB. If everything appears correct, then drill the holes in the base. The smaller holes for the PCB and heatsink that sit in the vented region of the base can be tricky to drill, but if they end up slightly out of the marked positions, that should not be a big problem. In the worst case, you will just have to enlarge these holes slightly. Also drill a 3mm hole for the mains Earth in the base. Place it near the mains receptacle, but clear of the vented region. As with the other Earth holes, sand the area around it to expose the underlying metal. The transformer is quite heavy so take care not to drop it while working with it. Feed the bolt through the bottom of the case, then place one of the rubber gaskets over its shaft on the inside. Lower the transformer into place, rotating it so that the wires are close to where they need to connect. The second rubber gasket goes on top of the transformer, followed by the dished metal plate with its convex side facing down. Slide the small washer in place, thread the nut onto the bolt and tighten it up to a reasonable degree, so the transformer is held securely in place. Do not overtighten it or you could damage the transformer windings. Remove the two 9mm tapped spacers from the PCB that are nearest to the heatsink. Alternatively, if you haven’t already fitted them, fit the two spacers December 2019  89 furthest from the heatsink but leave the other two off. Getting the PCB into position in the case can be tricky due to the weight of the transformer. We found that it was possible to balance the case on its edge by using the weight of the transformer to hold it upright. Start by feeding one M3 x 10mm Nylon machine screw through the base of the case and into the heatsink, making sure to thread it through the acrylic spacer. Then fit the other three Nylon machine screws to hold the heatsink in place. This should also hold the PCB in place, for now. Metal screws cannot be used on the heatsink as this would connect the live heatsink to Earth. Use two machine screws to secure the front of the PCB to the bottom of the case. Now is a good time to attach the feet to the case. We used taller feet than those included with the enclosure, as those were so short that the transformer mounting bolt head was still touching the bench with them in place. Taller feet also provide more space for cooling air to escape via the underside vents. Rear panel and fan mounting The fans can now be fitted. They are mounted to the rear panel on spacers. Ideally, they should be as close as possible to the heatsink, but not touching. Take one fan and thread four 32mm machine screws through the corner holes. Fasten them to the fan using the 15mm-long M3 tapped spacers. These will sit against the rear panel, so if there is room to bring the fans closer to the heatsink, nuts or washers can be placed under the spacers. Just make sure that the fans don’t touch the heatsink fins. Now separate the fan filters/guards into two pieces and place the fans on the inside of the rear panel and the guards on the outside. Attach the fans using 9mm long M3 machine screws through the guards and rear panel, and into the tapped spacers attached to the fans. Clip the fan filters back into place on the guard frames. With the PCB and transformer in place, you can mark and cut the required cutouts in the side panels, to clear the internal components. You can see how much material we had to remove in our photos. There is a fair degree of overlap between side, top and bottom panels, so slight inaccuracies in cutting the side panels will be hidden. The two 80mm fans we used were specifically chosen for their high flow rate. They’re Digikey P122256 24V models, available from digikey.com If you substitute other fans they may not have the essential cooling properties of these ones. Firmly hold the side panel in a vice using timber off-cuts to protect the finish. Make the marked cuts with a hacksaw. If the panel vibrates as you are sawing, try clamping it closer to where the cut is being made. Check that the panels now clear the transformer, PCB and heatsink. Once everything fits together correctly, dress any sharp edges of the side panels with a file. The side and top panels will also need to be Earthed. This can be done via the remaining sections of the mounting tabs. These are already slotted, so you don’t need to drill any holes. Just remove the enamel from a small area on one of these tabs, where the Earth eyelet will be attached later (see photo at left). Use an area near the back of the side panels, as the Earths will all connect back to the rear panel. For the top panel, choose a location opposite the Earthing location on the bottom panel, which is otherwise clear of components. Drill a 3mm hole and sand the inside of the panel as for the others. Making the final connections It’s not immediately obvious here but each of the mains spade connectors on the IEC (input) socket (upper left of pic) are covered with a clear shroud. Also note each of the removable case panels has its own Earth wire attached, connecting back to the main Earth point on the rear panel (alongside the IEC socket). 90 Silicon Chip Australia’s electronics magazine The leads to the fans, LED, panel meters and thermistor can be plugged into their respective board connections. The leads for the banana sockets screw into terminal block CON1. Ensure that they are connected with siliconchip.com.au the correct polarity, ie, red wire to + terminal. Mains wiring The transformer needs to have spade crimp lugs fitted to mate up with the IEC plug receptacle and bridge rectifier. The transformer we used has two 115V AC primary windings, which are intended to be connected in parallel for 110-120V AC mains and in series for 220-240V AC mains. The secondary windings are 40V AC each, and in this application, they need to be wired in parallel. Also, the integral DPST switch in the IEC input socket is not joined internally to mains Active or to the fuse. It instead has separate spade lugs to make connections. So we will need two short leads, one brown and one blue, to make these connections. Make sure there is no chance that a mains cord can be plugged in while you are working on the mains side of the circuit. Cut a 100mm length of brown wire and another 100mm length of blue wire, stripped from 10A-rated mains flex or a spare 10A mains cord. Strip both ends of both wires and securely crimp spade lugs onto them. Insulate the exposed metal using heatshrink tubing. Once you’ve made up those two wires, plug them into the rear of the IEC socket, with one going from the fused Active terminal to one pole of the switch and the other going from the incoming Neutral lug to the other pole of the switch. Do not connect them both to the same switch pole! Now is also a good time to insulate the exposed metal strip on the back of the IEC socket using neutral cure silicone sealant, to make working on the inside of the Supply a bit safer. To wire the transformer primaries in series, solder the grey wire to the purple wire and cover the joint using two layers of heatshrink tubing. Remember to slip the tubing over the wires before soldering them. If you are using a different transformer than the one we specified, check the manufacturer’s instructions for wiring it up to a 230V AC supply. Next, fit spade connectors to the transformer’s brown and blue (primary) wires and insulate them with heatshrink tubing. Push these onto the two remaining switch terminals on siliconchip.com.au A B A close-up of the rear of the Supply showing (A) the main earthing point and (B) the Presspahn insulation forming a barrier between the high and low voltage sections. Don’t leave these out: they’re for your safety! the mains socket, so that the wires going to the two switch poles match (ie, brown/brown and blue/blue). It’s essential that you now use multiple cable ties to tie all the mains wiring around the IEC input socket together, so that if any of the wires come loose, they won’t flap around the case and potentially make contact with the heatsink, PCB or any other non-mains conductors. You will also need to fit a Presspahn insulating barrier alongside the heatsink and PCB, so that if a mains wire does somehow come loose, it cannot come in contact with those parts. Cut the sheet of Presspahn to 105 x 208mm and score it 20mm in from one long edge, making a 208 x 20mm foldable section. Now fold that part by 90°, place it in the case alongside the heatsink and drill two holes in the base, through the bottom of the case, close to each end. Attach it to the case using 6mm M3 machine screws and nuts. The photo opposite shows what it will look like when you’ve finished. This piece will come close to touching the lid when it’s attached forming an insulation barrier between the heatsink/PCB and the mains wiring. You will need to use side cutter to make two cuts along the top edge and fold it down, for the transformer secondary wires to pass through. Again, see the photo for an idea of how this was done on our prototype. Earth wires The next step is to make and fit the panel Earths. Five green/yellow wires are required with eyelet connectors crimped to each end. These will go from the rear panel Earth screw to the Australia’s electronics magazine other panels. A sixth wire is needed, with a spade lug at one end (to suit the mains socket) and an eyelet at the other, to go to the rear panel star Earth point. None of the crimp connections need to be insulated. Cut the Earth leads to length, giving enough slack so that you can pull the panels apart later, and so that they can avoid any components which might be in the way. The lead for the top panel should have more slack than the others, as it will need to allow the top panel to be detached and moved out of the way while still being connected to Earth. Once the wires have been made up, plug the spade terminal onto the Earth terminal of the mains socket. Thread a 12mm M3 machine screw through the rear panel hole, then place a star washer over the screw shaft, followed by the six Earth wire eyelets. Secure with an M3 hex nut and tighten well. Then add another nut on top, doing it up moderately tight, to act as a locknut. Now terminate the other end of the five remaining Earth leads to the five other panels similarly. The screw heads should be on the outside the case, with the eyelet connected to each panel through the star washer, with the screw held in place by a nut done up tightly. The front Earth binding post (if fitted) should have its eyelet placed on top of the front panel Earthing eyelet. The final connections to be made are from the transformer secondaries to the bridge rectifier (BR1) on the heatsink. To parallel the secondaries, solder or crimp the orange and black wires into a spade together and insulate it with heatshrink tubing. Do the same with the yellow and red wires, December 2019  91 The underside of the Power Supply case, showing the locations of the holes required for the transformer (the big black bolt), the heatsink (Nylon screws on/near ventilation holes) and the PCB mounting pillars (right side of pic) The single screw on the left side is for the case Earth. All holes are 3mm with the exception of the transformer mounting (we used a 8mm bolt). into a second spade lug. Again, if you are using a different transformer, you should check this configuration as it may be different. Plug the two spades on the AC lugs on the bridge rectifier. Check that everything else has now been connected Final assembly The back, front and sides of this case can be tricky to assemble. You might find it easier to join the front, back and sides together as a unit and then slot this onto the bottom panel. Screw two of the panel screws into the sides, securing them (and thus the front and rear panels) to the bottom. Check that these screws do not foul the transformer or PCB as you do this. They are much longer than necessary, so can be trimmed, if it comes to that. You can test fit the case lid as well. It should slot onto the remainder of the case, with the last two screws used to secure it. But leave it loose for now, as we will need access to the PCB for the final tests and calibration. Now is a good time to tidy up the wiring. Use cable ties to secure the wires into neat bundles (you should have already tied the mains wiring together). The slotted ribs on the side panels are great places to attaching the cable ties, holding the wire bundles out of the way. This is also a good chance 92 Silicon Chip to run your eye over everything and make sure you can’t spot any wiring or construction problems. Final testing Ensure nothing is connected to the supply outputs and that the front panel knobs are wound down to their minimums. Connect mains power and switch the unit on via the rear panel switch, keeping yourself well clear of all the internals. It’s best to leave the wall socket switch off, ensure the IEC input socket switch is on, then stay clear of the unit while switching it on at the wall. The front panel meters should light up and should all have readings close to zero; if they do not, power off and check for problems. The temperature reading on the Five-way Panel Meter should be around ambient. If the temperature is above 20°C, then the fans may start up. Connect a multimeter on its volts range to the output terminals, with the output switch on (down). The reading should be 0V. If not, shut down and check for faults. If all is well, turn up the current limit pot to slightly above zero, maybe to around one-tenth of its range. At the zero position, the output is completely inhibited. Slowly advance the voltage pot; you should see the voltages on the Australia’s electronics magazine meter rise. If this is the case, then we can calibrate the voltage display. Dial up the voltage until you get 50V DC across the output terminals. If it does not reach 50V at its maximum, adjust VR1 to allow this. Now adjust VR5 and VR6 until their respective meters (set voltage and actual voltage) are both showing 50V. This will probably be at around a third of their range from the minimum position. So far, all the work is being done by REG3. We will now test that the Supply will hand off to the current boosting transistors at higher currents. Dial the voltage pot down to the minimum and connect a 1kΩ resistor (1/2W is fine) across the output binding posts. Now dial the voltage up to 20V; this will be just below the power limit of a 1/2W 1kΩ resistor. Check the voltage across the 68Ω resistor near REG3. It should give a reading of around 0.6V, the base-emitter switch-on voltage of transistor Q3. If the reading is above 1V, then REG3 is passing all the current, and the transistors are not taking the load. Power off the unit, give it a minute for the capacitors to discharge and check for problems around the heatsink-mounted transistors. Assuming all is well, dial the voltage and current down and remove the 1kΩ resistor. We can now calibrate the current meters. You can connect an ammeter (or multimeter at 10A setting) directly across the outputs, although this will involve running the PSU at maximum dissipation. It is a good idea to connect a high-power series load resistor if you have one. We want the Supply to be delivering 8A to provide the best calibration. Dial up the voltage slowly; if you only have an ammeter connected across the outputs, you should not see a voltage reading much higher than 1V (depending on lead and load resistance). If it goes much higher, that suggests that there is a problem with the current limiting. The voltage will be higher if you have a series resistor connected. As you advance the current limit pot, assuming the set voltage does not match the actual voltage, that means that current limiting is occurring. The fans should start running if they are not already. Continue winding it up until the meter shows 8A. If it does not reach siliconchip.com.au 8A, then adjust VR2 to fine-tune the maximum current limit. Now adjust VR7 and VR8 until the Five-way Panel Meter (or your individual panel meters) show 8A for both the set current and actual current. These pots will need to be wound to around 2/3 of their range from the minimum. At this stage, the Supply will be dissipating close to 400W, so the temperature will be steadily rising and the fans will be working harder as it does. You can use a contactless (IR) thermometer to check the heatsink temperature, which should be close to what’s shown on the Panel Meter. If you leave the current set to 8A, you can test the thermal limiting. When the temperature reading gets to around 80°C, the limiting LED should come on, and the current will drop. You may also hear the fans run a bit harder too. This is not a ‘boost’ mode, just the effect of the sagging DC voltage disappearing as the load is reduced. If the temperature keeps rising past 80°C with no change in the output current, then shut the Supply down and check for faults in that part of the circuit. If it does enter limiting, then the Supply is working as designed. Dial the current and voltage down to their minimums and let the fans run for a moment so that the heatsink cools down, then turn it off and disconnect your test load. Finishing up Now that everything is functional, it’s just a matter of a few finishing touches. Secure any loose wiring with the cable ties. The wires on our transformer were not too long, so they did not need to be fixed to anything. If yours are significantly longer, you can use self-adhesive plastic cable clamps to tidy them up. The fan and thermistor wires can be bundled together and fixed against the right-hand side panel with adhesive wire clips. Similarly, the output wires to the binding posts should be attached to the base of the case with adhesive wire clips. The other wires to the front panel can be bundled together with cable ties. Since they do not travel far, they should not need to be secured to anything else. siliconchip.com.au The Earth wires should be clipped in place if there are any that might move around excessively. Take care with the lead for the top of the case if it has a lot of slack. You may like to fit a cable clip to the inside of the top of the case to secure it. Secure the top panel in place with the two supplied screws. The High Power Linear Bench Supply is now complete. Variations While we aimed for 50V output voltage in our design, necessitating the 57V rail, you can use a lower voltage transformer too. As long as the 24V regulator can still deliver 24V, the Supply will still work. To use a lower voltage transformer, you may need to reduce the value of the 220Ω 5W resistor, to ensure the input of REG1 always stays above 26V. You can also adjust the upper output voltage limit downwards using VR1. VR1 may even need to be increased in value (eg, to 20kΩ or 50kΩ) if a very low output voltage is desired. The current capacity of the output transistors is much higher than the 2A each we have chosen, but thermal considerations limit their operation. You could tweak the PSU to provide a higher output current if the input voltage (and thus total dissipation at zero output voltage and maximum current) is reduced. The PCB tracks, CON6 and the wiring can handle up to 10A, so this is about the practical limit without making major changes. Note that you may need to reduce the value of the 27kΩ resistor in series with trimpot VR2 to set the current limit to 10A. Fan considerations We chose a particularly high-powered pair of fans to ensure that the output transistors will be cooled as much as possible. The 33Ω series resistor is suitable for these fans, but may not drop enough volts if different fans are used, particularly those with a lower current draw. Its value should be chosen to provide a 9V drop (from 57V to 48V) at the typical current draw of the chosen fans. A 5W resistor should be suitable for up to around 500mA under these conditions. SC Australia’s electronics magazine Fig.9: this front panel artwork is reproduced here at 75% life size, so will need to be copied at 133% to fit the panel. A full size version can be downloaded from siliconchip.com.au December 2019  93 Nicholas Vinen reviews . . . Ausdom ANC7S Noise Cancelling Bluetooth Headphones from Altronics These rechargeable Bluetooth headphones feature active noise cancellation technology and offer outstanding sound quality. They cost much less than you would pay for most name-brand noise-cancelling headphones like Bose or Sony. A ltronics sent us a pair of these Bluetooth headphones to review. We understand that while they are a relatively new product, they have been selling well. First, a bit of background: I find jet engine noise very bothersome, so I need to use something to drown it out. Without something to block that engine noise, my ears ring for days after a long flight. I also find the headphones supplied by airlines very poor (at least in economy class). They make my ears sore after hours of use, and I have to turn the volume up very loud to hear the dialog over the engine noise, which only makes the ringing ears worse! The situation is slowly getting better, but I still regard airline-supplied headphones as being virtually unusable. So, I think you really need a good pair of headphones to make a long flight tolerable. They should ideally be able to plug into the plane’s entertainment system (in case they have something worth watching – not a given, unfortunately). I also like to be able to play music from my phone (set to flight mode). Some airlines will allow you to use Bluetooth, and most phones will let you switch it on even in flight mode. Failing that, you can use a cable connection. Check with your airline first, though. A handful of airlines won’t let you use a phone in flight, even in flight mode; primarily those based in mainland China. Bizarrely, they won’t stop you from using a tablet, even if it can make phone calls. Of course, in that case, you still use flight mode. How do they stack up? In my family, we have several pairs of active noise-cancelling (ANC) Bluetooth headphones of various makes and models. They were purchased mainly for use when travelling overseas, especially dur94 Silicon Chip ing flights; some of them were quite cheap and some not so cheap. So I have a few ‘reference points’ to compare with these headphones. First, the good news: the sound quality is excellent. I find the bass/mid/treble balance and clarity very good. The bass is perhaps not as ‘punchy’ as the best Bluetooth headphones I have tried. But in terms of overall sound quality, they are very good, limited only by Bluetooth digital compression (which is not too bad). And especially when you consider the price, the sound quality is quite astounding. In fact, I would put these headphones right up there with some very expensive Sennheiser, Philips and other name-brand hifi headphones in terms of overall sound quality, including distortion performance, frequency response and bass reproduction. Importantly, they don’t have the excessive boomy bass that is quite common these days. The bass is present and well defined, but not over-the-top. They are also very comfortable, which is very important for any listening session, fitting snugly over the ears but without undue pressure. The surrounds are quite soft, which helps, and they form a pretty good mechanical seal, which helps keep out external noise even without using the ANC feature. As with most Bluetooth headphones these days, they contain an internal lithium-based battery which is recharged using a USB cable (micro type-B). Charging time is around two hours, and a full charge lasts for about 18 hours of use, enough for the longest flights. A USB charging cable is supplied, along with an audio cable with 3.5mm plugs each end. Australia’s electronics magazine siliconchip.com.au Here’s what you get with the Ausdom ANC7S Noise Cancelling Headphones from Altronics. There’s the headphones themselves (!), a soft drawstring carry bag, a micro-USB charging cable, (charge from any USB or 5V DC source), a stereo headphone cable and a user manual. Recommended retail price is $139.00, including GST (Cat C-9021A). Bluetooth pairing is effortless (just follow the instructions in the booklet). And note that the noise-cancelling switch is separate from the Bluetooth controls. So you can easily engage ANC without actually listening to any audio, and similarly, you can use them like regular headphones (wired or wireless) without ANC if you are at home or in a more quiet environment. The Bluetooth range meets or exceeds the stated 10m; I was able to get it to work over around that distance, even with intervening obstacles like bookshelves. But the effectiveness of the active noise cancellation is a little disappointing. While it is effective enough to knock back a lot of the background jet noise you will experience in-flight, it hardly provides the cosseting experience that (much more expensive) Bose, Sony and Panasonic noise-cancelling headphones can offer. All ANC systems are more effective at lower frequencies (because the longer wavelength is easier to cancel), but this system lets through a lot more mid-to-high-frequency noise than I would like. With my wife’s Sony MDX1000 headphones, they reduce the background noise so much, you can forget you are on a plane. They’re so effective that you probably won’t even notice if someone is talking to you at a normal volume. While I have not yet taken the Ausdom headphones on a plane, based on tests I conducted with fans and other noise sources, I do not think you would get quite the same experience. You would be a lot more comfortable, but you still would be aware of the engine noise. For example, I tested these headphones in an office near a busy siliconchip.com.au road, with a closed window. While the already-muffled traffic noise was dulled by turning ANC on, it did not vanish entirely. But perhaps I am spoiled; the MDX1000 are considered one of the best noise-cancelling headphones. Other reviewers have compared the ANC7S favourably to some well-regarded Bose noisecancelling models, Conclusion Despite my criticism of the noise cancellation, I still think these headphones are good value, especially if you just want a good pair of headphones to use at home, in the office etc. And if you are not as noise sensitive as me, or lucky enough to be on a modern aircraft with lower than average engine noise, you may be satisfied with the noise cancellation performance. Similarly, the ANC7S may well be effective enough to allow you to listen to music on a train or bus with a lot less annoying background noise, or perhaps reduce background noise in an office or near a busy road. If you’re listening to some good music, you might find yourself cranking the volume up a bit more to enjoy the excellent sound quality, and that will go a long way towards drowning out any background noises anyway! The ANC7S headphones can be purchased from your local Altronics store for $139 including GST (Cat C9021A), or via their website (siliconchip.com.au/link/aav5). More information on the ’phones is also available at that link. You may also want to pick up their “plane socket adaptor” (Cat P0318 – $4.95) at the same time, to allow a wired connection to the older-style dual plug airline sockets. SC Australia’s electronics magazine December 2019  95 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. Dot-matrix scrolling text display This circuit allows you to type and store your favourite text messages, then choose and display them later by pressing a button. It has three scrolling speed modes (slow, medium, and fast), selectable by another pushbutton. The selected message and scrolling speed are stored in the micro's EEPROM. The unit can also display the time and date, plus the ambient temperature in degrees Celsius or Fahrenheit. It's based on a pair of 8x8 LED matrices. These are rotated when in use, as shown in the photo below. The following description refers to rows and columns as shown in the circuit diagram; these are swapped when viewed. The corresponding columns (cathodes) of both matrices are connected together so that there are eight combined columns in total, which are driven by IC2, a ULN2803 eight Darlington array, which can sink 500mA at each of its eight outputs. IC2's eight control input pins are connected to the PORTD digital outputs of the ATmega8A micro, IC1. The 16 rows (anodes) are driven individually by the outputs of two 74HCT299 eight-bit shift register ICs (IC3 & IC4), which are fed serial data from PORTB.0 and PORTB.1 of the micro. These shift registers activate each row for 1ms while IC2 drives each column cathode low, lighting up to 16 LEDs at a time. This is too fast for the eye to see, so the display appears to be continually lit. The use of the two shift registers means that only two microcontroller I/O pins are needed to drive the 16 rows (anodes) of the two LED matrices. IC1 runs from its internal 8MHz oscillator, but it also has a 32768Hz crystal (X1) between pins 9 and 10, which connect to its internal oscillator amplifier. These are used to clock the hardware counter TIMER2 asynchronously, for timekeeping purpos96 Silicon Chip es (the aforementioned clock). The output pin of the LM35D analog temperature sensor (TS1) is connected to the analog-to-digital converter (ADC) of the micro through its ADC0 input pin (pin 23). The LM35 is a precision temperature sensor IC with an output of 10mV/°C. It has a typical accuracy of ±0.25°C and only draws 60µA. The sensor output voltage is 0V at 0°C and 1V at 100°C (100°C × 10mV/°C). For Fahrenheit display, the software performs the °C to °F conversion (°F = °C × 9 ÷ 5 + 32). Message display is handled by a subroutine in the code called “Selectmessage”. There are 10 messages available. Message 1 is used for time, date and temperature display. The other nine messages can be userdefined text of up to 70 characters Australia’s electronics magazine (including spaces). These are set in the software and fixed once the code has been compiled and uploaded. Initially, the message scrolling speed is slow. To change the speed to fast or medium, wait until the last character of the message appears on the display and then press and hold pushbutton S3 until the characters appear again and the speed increases. This takes a second or two. The new speed mode is stored in the EEPROM so it will be remembered even when the unit is switched off. The circuit initially displays message 1. To change the message, wait until the last character of the current message appears on the dot matrix and then press and hold pushbutton S2 until the display blanks out. Then release S2 and press reset button S1. It will then display message 2. To see message 3, 4, etc. follow the same steps. After message 10, the circuit siliconchip.com.au will display message 1 again. As with the scrolling speed, the message to display is stored in EEPROM. The device can be powered by a 5V DC regulated power supply such as a plugpack, connected to CON1. S1 is the power on/off switch while schottky diode D1 provides reversed supply polarity protection. My prototype was built on veroboard. The software is written in BASCOM, and the files (dotmatrix.bas/ dotmatrix.hex) are available for download from siliconchip.com.au Mahmood Alimohammadi, Tehran, Iran. ($75) siliconchip.com.au Hearing loop amplifier for Android phones Railway enthusiasts sometimes like to record station announcements. You can do it with a normal sound recorder, but extraneous noise often spoils the recording. Luckily, most modern stations have hearing loops for the hard-of-hearing – these broadcast announcements to people with Telecoil-equipped hearing aids. The announcements come through clear, without the background noise. Stations and other places with hearing loops have a distinctive blue and white ear sign. Australia’s electronics magazine This amplifier lets you receive announcements through the station’s induction loop system, even if you don’t have a hearing aid. It’s a onetransistor audio amplifier powered by the phone’s electret microphone connection. Audio is picked up from the induction loop with a 10mH RF choke. Or, as described in the Hearing Loop Receiver (September 2010; siliconchip. com.au/Article/286), you can use a Xenon flash tube trigger transformer like the Jaycar Cat MM2520. I mounted the parts on a narrow strip of matrix board. This can be encased in heatshrink tubing for protection, and to make its use less conspicuous. If you don’t want to solder to the 3.5mm four-connector plug, it's easier to chop the cord off an old hands-free headset instead. I was lucky and found one lying on the street that had been run over, but its cord was still OK! The circuit shows the most common jack connection, but some devices may require the dotted ones instead. You can use a phone app like Voice Recorder to make recordings. Test the amplifier by recording while holding the amplifier near an electronic noise source like a power supply, modem, computer screen or electrical wiring. You should hear the hum change on playback as you move it around. If you pick up a ‘chug chug’ noise from the phone itself, try setting it to Flight Mode while recording. Recording train announcements isn’t this amplifier’s only use. You can also use it to record audio from computer speakers, fixed-line telephones or a home hearing loop. And electronic music composers will find it an interesting source of noise material for their mixes. Peter Parker, Chelsea, Vic. ($80) December 2019  97 Discrete switching LED driver In the early 2000s, I came across a circuit online called a “Black Regulator” (apparently named after its inventor; www.romanblack.com/smps/ smps.htm). I was intrigued because it was an elementary circuit using only discrete parts but apparently functioned well as a switchmode voltage regulator. But I needed a switchmode LED driver, as I had just gotten a hold of one of the then-new high-powered white LEDs, which are ideally driven with a regulated current. So I decided to adapt the design to work as a current regulator instead. The circuit I came up with is shown here. It fits on a single-sided PCB measuring 50 x 33mm, using all throughhole components. The artwork for this board is available for download from siliconchip.com.au if you want to make your own. It works as follows. PNP transistors Q1 and Q2 form a constant-current source, delivering about 2mA to the collector of Q5, regardless of the supply voltage. NPN transistors Q5 and Q6 form a current mirror, and since the current through Q5 is fixed at 2mA, Q6 will also 'attempt' to sink a constant 2mA. The 2mA through Q5 produces around 60mV across its 33W emitter resistor. The ~2mA sunk by Q6 goes through the resistor chain between its collector and the positive supply. This initially causes the PNP Darlington formed by Q3 and Q4 to switch on, allowing current to flow from the supply, through inductor L1, charging up the output capacitor and possibly supplying current to the LED(s) at the output. As the current through L1 and the LED(s) increases, the voltage drop across the 0.22W resistor in their ground path increases. Once this reaches about 60mV (when the output current reaches 272mA [60mV ÷ 0.22W]), the emitter voltages of Q5 and Q6 equalise. Once this voltage exceeds 60mV, Q6 starts to switch off. This then cuts off the base drive to Q3 and Q4, so they also switch off, and no longer admit current to L1. L1's magnetic field then starts to collapse, forcing current to continue 98 Silicon Chip to flow, but this current must then come from ground via D1. This also causes the collectors of Q3 and Q4 to around -0.5V, and this transient is coupled to Q5's emitter via the 2.2nF capacitor, resulting in clean switching. Once the 2.2nF capacitor discharges and the voltage across the 0.22W resistor has dropped considerably, the initial conditions are re-established and so Q6, Q3 and Q4 switch back on and the process repeats. The circuit performs surprisingly well. I tested it with a 1W Luxeon LED and an input voltage between 8-20V; the output current remains well regulated, with an efficiency of between 70% and 80% (higher at the lower end of the input voltage range). Similar results were achieved for 3W LEDs. I have also used this circuit for driving the solenoid in a magnetic door strike. This allowed me to have a highefficiency driver with a controlled current. It also meant that I can to safely short-circuit the door strike to allow me to open the door. Phil Prosser, Prospect, SA. ($75) Australia’s electronics magazine siliconchip.com.au Low-voltage 3-phase Induction Motor Speed Controller I built the excellent 1.5kW Induction Motor Speed Controller (April-May 2012 & August 2013; siliconchip.com.au/Series/25). I wanted to experiment with the circuit and software, but decided that this wasn’t a good idea with the mains-powered version, as it could be dangerous if I made a mistake. However, with just three extra ICs, it can operate on much lower DC voltages to control a permanent magnet three-phase motor, and it is then quite safe. Examples of motors that this modified circuit can drive include those extracted from old hard disk drives (HDDs). My design uses the same micro, programmed with the same 1010512B.HEX file from siliconchip. com.au/Shop/6/792 But I’m using three BTN7970P Mosfet half-bridge ICs to provide the output drive. siliconchip.com.au These are available from eBay for around $7 and are rated at 45V/40A, but I decided to stick with a 12V supply. Note that these ICs are obsolete, while a BTN8962TA can be used as a replacement, it’s only available in a surface-mount package. The BTN7970P drivers are also quite efficient, with a typical onresistance of 16mW and a quiescent current of 7µA. They can be driven with logiclevel signals using PWM frequencies of up to 25kHz and have overtemperature shutdown, short circuit protection, over- and under-voltage lockout, adjustable slew rates and an internal dead-time generator. The 6.8kW resistors from the slew rate pins (SR, pin 5) to ground on IC4-IC6 set the slew rates to around 5V/µs, which is not the fastest the drivers can manage but more than Australia’s electronics magazine fast enough for this application. The 1kW resistors from the current sense pins (IS, pin 6) to ground allow the output currents to be measured by converting currents sourced by IC4-IC6 on that pin into voltages. However, the original IMSC did not have current monitoring, so those voltages are not fed to the micro. Current monitoring could possibly be added with some software changes. Since the circuit shown here is a modified version of the original Induction Motor Speed Controller, most of the part designators are the same, even though some have been removed (eg, there is no ZD1 but there is a ZD2). Its operation is identical. You can see a YouTube video of my prototype in action at: https:// youtu.be/rMe7PzOnpvo John Russull, Cambodia. ($80) December 2019  99 Vintage Radio By Associate Professor Graham Parslow The Ferris 106 “portable” car-home-radio “Robust” is the word that sums up this top-shelf portable radio. Everything has been done to make this a sensitive radio, shielded against interference, particularly from a vehicle ignition system. While it is portable, being so robust means that you would have to be fairly strong to carry it long distances, as it weighs around 8.5kg. The Ferris model 106 was sold between 1954 to 1958, a time when valves reigned over expensive, lowpowered transistors. This radio has six valves and is the final evolution of portable radios using 1-series miniature valves, which were in vogue for roughly a decade from 1948. The advertisement for the model 106 (reproduced later) shows the places that this ‘luggable’ could be used. It weighs 8.5kg with batteries and mounting brackets, 6kg without. Fortunately, it has a comfortable handle. This radio’s place in history Not long after the model 106’s production run ended, Ferris moved on to building transistor radios that used less power, weighed less and were more compact. Two of those germanium-transistor radios (successors to the model 106) have been described in Silicon Chip Vintage Radio articles; one in August 2002 (Ferris 214 car radio; siliconchip. com.au/Article/6751) and one in May 2008 (Ferris 174 portable; siliconchip. com.au/Article/1832). 100 Silicon Chip The model 106 sold for 50 guineas (£52.10s) when the average weekly wage for an adult male was £12.10s. That makes the current equivalent purchase price around $5000; a figure almost beyond comprehension. As a ten-year-old in 1958, my pocket money was 2 shillings a week, so it would have taken me ten years to save for this radio! A car radio was a significant fraction of the cost of a new car, so many cars were sold with a metal blank in the dashboard-space for a radio. There was an obvious market for adding a radio further down the track, and if that radio could also be a home and picnic radio, so much the better. Ferris did not entirely have that niche to themselves in Australia, because AWA and Astor also catered to that market. The very first radio to be mounted in a “horseless carriage” (steam driven) in 1901 was made by Guglielmo Marconi. It received only Morse code, so it was not the true antecedent of this radio. Most people would give that honour to the Motorola Company in the Australia’s electronics magazine USA. In the 1930s, Motorola worked out how to incorporate an aerial into a car, largely overcoming the ignition spark-generated noise radiated from the copper distributor wires. The Ferris Brothers were not far behind after becoming an incorporated entity in 1934. Circuit description The Ferris 106 circuit has a fairly standard configuration for a five-valve superhet with an RF amplification stage. It does have a somewhat complicated antenna switching arrangement, to suit its role as a multiple-purpose car/home/portable radio, along with the necessary dual (mains/battery) power supply. This radio has four knobs; the lower pair are for volume (R9) and tuning (G1-G3), while another knob acts as the power switch and also selects between mains and battery power (S2). The final knob selects which antenna to use: the car antenna, ferrite rod or “portable mode”, with the external antenna and ferrite rod connected in series (S1). siliconchip.com.au The Ferris 106 is a 5-valve superhet with an RF amplification stage and single pentode Class-A output stage. The valve heaters are connected in series, allowing a single full-wave rectifier to supply both the HT and filaments, the latter coming via a 2.3kW dropper resistor (R18). While wasteful, this does keep the power supply relatively simple, despite it having battery and mains power options, controlled by switch S2. Note also the complicated external/internal antenna switching via switch S1. The signal is received by a plug-in external aerial or a ferrite (loopstick) aerial (L3) concealed in the carry handle. The external aerial socket is for a standard car-aerial termination plug, although a simple wire antenna can also be connected. The position of S1 shown in Fig.1 is intended for use in a car. Switch S1 connects the vehicle’s aerial to the aerial coil (L2), which is designed to match well with the characteristics of a car antenna and has a secondary forming a tuned circuit with one gang of the three-gang tuning capacitor (G1). The second position of S1 is the “portable” position and couples the signal from the external aerial directly to tuning gang G1 and the control grid of the 1T4 RF amplifier. In this case, the RF input becomes untuned. The loss of gain is more than made up for by the RF amplification stage, and this has the advantage that the set’s performance is less dependant on the aerial. Inductor L1, the red spiral coil at the rear of the chassis, is not there to act as a filter. Instead, it exists to provide a good impedance match between the radio input and a typical vehicle antenna. This is necessary because short antennas as used in cars have a relatively high capacitance and so L1 is needed to prevent the capacitance of this aerial from detuning the first stage of the radio. siliconchip.com.au In the third position of S1, only the ferrite ‘loopstick’ aerial and tuning trimmer capacitor C2 connects to the control grid of the 1T4 and tuning gang G1. This allows the ferrite antenna to be separately tuned for best performance, without affecting the set’s performance with an external aerial. The 1T4 valve is a versatile RF amplifier used both for RF preamplification and IF amplification in this radio. Amplified RF is passed by L4 to the tuned circuit formed by the secondary of L4 (fine-tuned by an adjustable slug) and the second gang of the tuning condenser (G2). The 1R5 is almost invariably the mixer-oscillator valve of choice in portable valve radios after 1948. The oscillator is driven by the tuned cir- Australia’s electronics magazine cuit formed by the G3 gang of the tuning capacitor and inductor L5. T1 is the first IF transformer, passing the 455kHz difference signal between the tuned frequency and the higher oscillator frequency. After further amplification by a second 1T4 valve, the audio signal is derived by diode detection of the signal at the secondary of T2, using the 1S5’s internal diode. The negative-going output additionally provides negative feedback (AGC) to the preceding valves via resistors R1 and R5, in proportion to signal strength. Volume control is effected by 1MW potentiometer R9, feeding audio to the control grid of the 1S5 valve. The output from the 1S5 anode is conventionally coupled to the grid of the 3V4 December 2019  101 Above: the bottom of the Ferris 106’s chassis. All the components are original and did not need to be replaced for the radio to work. Note the vertical Earth strip down the centre of the chassis. Below: the top side of the chassis has the valves, IF transformers, power transformer and three-gang tuning capacitor (G1-G3) in the lower right. be inserted into either of two bayonet sockets. When the plug is in the socket shown in the circuit diagram, the internal speaker is connected. In the other socket, the internal speaker is shorted out, and only the external speaker is fed audio. This is not a particularly elegant way to handle connecting an external speaker, but it does avoid the need for another switch. The shorting plug can be seen in the under chassis photo, on the left. The plug is tethered so it can’t be lost if it falls out or is removed. The power supply is configured as many other contemporary dual-power portables were. A 6X4 full-wave rectifier produces a DC output of 105V. Series resistor R17 (1kW) cuts this back to 90V to supply 15mA to the HT circuitry. Another series resistor, R18 (a 2.3kW 5W wirewound type), derives 9V to feed the filament circuitry. This 2.3kW resistor dissipates 4W during operation, so it is not an efficient scheme. The valve filaments each get 1.5V, except for the 3V4, which has its twin filaments connected in series and so is fed 3V. Power consumption from the mains is 24W, which includes the power to drive the two lamps mounted at each end of the dial. On battery power, it only draws around 2W (the dial lights are not powered). When used in a car, the radio can run off its internal battery pack. But this is wasteful given that drawing power from the vehicle supply is much cheaper than discharging expensive batteries. So Ferris offered a 30W inverter which could be used to power the radio from a vehicle via its mains input. This could be left permanently connected to the vehicle, and the radio was plugged in while driving. Restoration output pentode. No tone control circuitry has been added, presumably to keep the knob count at four. Output transformer T3 has a primary impedance of 10kW, driving a 3.5W, 8-inch Magnavox loudspeaker. The 102 Silicon Chip speaker certainly acquits itself well in this radio, until reaching 250mW, a limitation imposed by the 3V4 output pentode. The shorting plug to the extension speaker is a metal cylinder that can Australia’s electronics magazine When I acquired this radio, it had no knobs, so the knobs shown here are not original. A clear photo of the original knobs can be found online at: siliconchip.com.au/link/aarj They are also visible in the advert shown at right. The front Ferris badge was also missing, so I had to acquire and fit a replacement. Perhaps due to the use of quality components, the radio worked the first time I tried it, even though the components all seem to be original. The paper capacitors are made by UCC and the electrolytics by Ducon. siliconchip.com.au An interesting feature of the chassis layout is that there is an Earth strap running through the centre which allows components to be neatly laid out in parallel or perpendicular to it, giving a pleasing and tidy appearance. The mains socket is the type used on toasters and electric kettles of the 1950s. I wanted to upgrade to a contemporary socket, so I installed an IEC socket to take a standard IEC power cable, as used for desktop computers, kettles etc (see photo at lower right). The front of the chassis accommodates the valves, tuning capacitor and mains transformer. The large central void leaves space for the Magnavox speaker, mounted on the front panel. The back-wave from the speaker can pass to the round grille hole in the rear panel via the battery compartment. The front and back panels are the same pressing. The external covering of the case is steel (it is magnetic) with an internal lamination of copper for high conductivity and shielding; a superior method of construction. The history of Ferris This history is abbreviated from a feature article in the Sydney Morning Herald in December 2007 (www.smh.com.au/national/tuned-in-to-consumers-needs-20071217-gdrtek.html). William Malcolm Ferris was the son of Henry Ferris, a railway worker. Ferris attended Sydney High School and made pocket money by repairing neighbours’ electrical appliances. He acquired the nickname “Chum”, and this was how he was usually known. He started his business in 1932, building home radio receivers one at a time in a rented flat above a Mosman butcher’s shop. His elder brother George joined him in 1934, and they established Ferris Bros Pty Ltd. In 1938, Chum released the Ferris Fultone 56, the first car radio designed and built in Australia. Despite the initial success of the Fultone 56, war intervened, bringing petrol rationing and shortages. Ferris Bros diversified into manufacturing devices to provide alternative fuel for cars. After the war, private car ownership took off, and in 1947 the brothers brought out the Model 74, which operated from either 6V or 12V car batteries or mains power. It was a great success, and the Ferris name soon became a synonym for car radios (or “wireless” sets, as they were known). The firm diversified into television and antenna production, and even released a line of model trains, which are now collectors’ items. The company grew in the 50s and early 60s into a business employing more than 700 workers. While best known for radios, Ferris Bros was a genuinely diverse operation, manufacturing TV receivers, laboratory equipment and even boat trailers and golf buggies. Ferris sold his business to the Hawker Siddeley group in 1970, and changes in tariff law soon meant that it was uneconomical to produce consumer electronics in Australia. By the mid-1970s it was possible to land a Japanese radio for less than the unassembled parts would cost locally. Ferris was made a fellow in the Institute of Radio and Electrical Engineers in 1981, in recognition of his many inventions and pioneering work in Australian electronics. In 1998, he donated a vast amount of advertising material, journals and an extensive collection of radios, spanning more than 30 years of production, to the Powerhouse Museum in Sydney. The Ferris 106 is an excellent example of mature valve technology and superior engineering, as you would expect from a company with a reputation like Ferris. SC siliconchip.com.au An advertisement for the Ferris 106. You can see the original bright red knobs and logo. The quality of this scan is poor, and we’re not too sure where or when this advertisement was originally published. An IEC socket was installed to replace the 2-pin mains cable, making it a bit safer and more convenient. Australia’s electronics magazine December 2019  103 Around this time of year, most people are thinking about Christmas decorations. And most people just rock on down to the store and buy whatever is the “go” this year. By Ross Tester B ut wouldn’t you like your place to be just a bit different to your neighbours? How about a lot different! As technical people, you could set your heights a bit higher . . . like building your own unique display. For example, you could build one (or dozens!) of the mini Christmas tree we featured in last month’s (November) issue (www.siliconchip.com. au/Article/12086). Or perhaps build the infinitely-extendable Christmas tree from November 2018 (www. siliconchip.com.au/Article/11297). But with the big day now only about three weeks away (or less!) maybe you’ve left your construction run a tad late. So what to do? Of course, we have an answer for you. You’ll need only a few minutes of your time (truly!) and you’ll end up with a multi-colour display that you can not only place, well, wherever you like but you can change it whenever you like and, best of all, it certainly won’t break the bank. cellent one of those! Australian mailorder house Oatley Electronics (www. oatleyelectronics.com) sells this “kit” for the princely sum of just $18 (plus P&P of course!). For this, you get a 5m roll of RGB LEDs – there are three combination red, green and blue LEDs every 50mm, Oatley’s Bargain Lightshow The IT130PACK2 kit consists of a 5m roll of RGB LEDs, a 12V/5A switch-mode power supply, the infrared controller (at left) with its pushbutton remote control (at right), a connecting cable (one end plugs into the controller, the other you solder to the LED strip and even a CR2025 button cell for the remote control. It’s not specifically sold as a Christmas Light display – but it makes an ex104 Silicon Chip Australia’s electronics magazine so you are getting 300 LEDs (and their resistors) all mounted on a self-adhesive, continuous strip. Incidentally, if 5m is too long, you can cut off the required length of LEDs where marked on the strip. You could, in fact, just run one 50mm length if that floats your boat! siliconchip.com.au There’s an on-line Demo . . . +12V This shows just one 50mm section of the 5m RGB LED strip. You can cut the strip to any multiple of 50mm if you wish. 330 150 150 330 150 150 330 Want to see what this controller can do? Check out the video at https://youtu.be/ rgMIOyeNNK4 150 150 THREE RGB LEDS PER 50mm RED GREEN BLUE Each 50mm section contains the three multi-colour LEDs and associated resistors. The copper section is where you solder the wires from the controller –the +12V (which may be black or white[!]) and the red, blue & green control wires. The anodes of all three LEDs are connected to the +12V supply via suitable current limiting resistors. The LEDs are switched by connecting their cathodes to the negative supply (via pads on the strip). The full 5m string will demand about 1A per colour. Light up all LEDs at once (ie, R, G and B) and you’ll need a supply rated at 3A or so. But included in the price is just such a 230V mains supply: in fact, it’s rated at 12V, 5A, so there’s more than enough headroom. combinations to give a wide range of colours and flashing modes. Some of the modes are music or sound-triggered from the small electret microphone inside the controller. The LED controller simply plugs in to an adaptor cable which is soldered to the LED strip (we’ll look at that onerous task in a moment!). And just in case you think Oatley might have left something out, there’s even a CR2025 button cell included for the remote control so you don’t have to go searching for one . . . But wait, there’s more! Connecting it all together Now you could simply connect the LEDs like that permanently but it would be pretty boring, wouldn’t it? Or you could stand there and flick/ change colours manually (not!). Also included is a small infrared LED controller – complete with a 20-button infrared remote control. This allows you to set a variety of patterns and colour combinations and, obviously, can be changed at will by pressing a different controller button. As well as selecting static red, green and blue colours, you can also select Here comes the hard part – connecting it and getting it going. OK, we’re kidding: all you need do is solder the four wires (+12V and R, G and B control) to the LED strip. Just a quick word of warning here: as is common practice in Chinese goods, the positive wire is probably white – but in our case it was black! The other three wires are green, red and blue so it’s pretty obvious where they solder to. Be very careful that you don’t bridge between the contacts because you will either have no control over those two channels or in worst case, you might do some damage to the infrared LED controller. All you need do now is work out where you’re going to run your 5m strip. As we mentioned, the backing is self-adhesive (double-sided tape) so it can stick just about anywhere. Will it be around the tree . . . or up and over your front door . . . or along the patio or verandah . . . or Where from; how much We already mentioned it comes from Oatley Electronics (www. oatleyelectronics.com) with a cat no of IT130PACK2. The whole “kit” used to sell for $22.00 – a bargain in its own right. But get in before Christmas, tell them you’re a SILICON CHIP reader, and it’s yours for almost 20% off – just $18.00 plus P&P of $8.90 That’s a bargain of a bargain! SC Soldering to the LED strip: the +12V pad is clearly marked – get it right and you can’t get the rest wrong! Plug the adaptor lead into the controller lead (notice the X symbols line up to each other), plug in the power supply – and that’s it! MULTIFUNCTION WATERPROOF 250W MPPT SOLAR CHARGER SOLAR POWER SYSTEM 5V SOLAR PANELS Combines a 12V/10A/180W Solar PICK UP ONLY: One Used Large 250W Solar TWENTY 45 x 90mm PANELS (8W) + 4x 1A Schottky diodes: SP4590 $10 TEN 80 x 120mm PANELS (10W) + 4x 1A Schottky diodes: SP80120 $20 0.5M / 7W / 12V LED BARS FOR AS LOW AS $3.33 EA.! Panel Plus a Genuine 30A 12/24V MPPT Solar Regulator SAKO SC-M-30A. Will deliver 16/8A into a 12/24V Battery IT144..... $120 Available in Pure White, Warm White, and Blue Search for IT117 on our Website Regulator and a 220V/50Hz 500W Modified Square Wave Inverter, with a Universal Power Socket: Meanwell Power Supplies CLG-150-20A: 15-20V: 7.5A …. IT134 : $29 HLG=240H-24: 24V-10A: …....... IT135 : $29 HLG-185H-48: 48V-3.9A: …....... IT136 : $33 SP-100-12: 12V-8.5A …..............IT140 : $19 IT131.... $39 OATLEYELECTRONICS.COM TEL:0428600036 NEAR WOY WOY ON THE CENTRAL COAST OF NSW siliconchip.com.au EMAIL: branko<at>oatleyectronics.com Australia’s electronics magazine December 2019  105 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 Making the H-bridge run from 24V DC Regarding the Four DoF Gamer’s seat project (September 2019; siliconchip. com.au/Article/11912), I’m interested in building a 24V version of the Hbridge designed by the author. I could have a go at it myself but thought that you would better know how to modify it to suit. I have several Linak 24V actuators to drive. (R. McG., Seven Hills, NSW) • The only changes required are to use a 35V-rated 100µF capacitor (25V is a bit too close to 24V) and to add ~1.8kW resistors between the collectors of Q1 and Q6, and the gates of Q2 and Q4, with 10nF capacitors in parallel. These capacitors will prevent the resistors from affecting the switch-on speed too much; however, given the relatively slow switch-off speed provided by the 2.2kW pull-up resistors, this may not be strictly necessary. Volume control for speech synthesis I’m building your Raspberry Pi Speech Synthesis design (July 2019; siliconchip.com.au/Article/11703). I know I can control the volume via the Raspberry Pi software, but I want a manual volume control knob. What is the best way to put a volume control potentiometer in the circuit? (B. R., Eaglemont, Vic) • The simplest way is to replace the two 1kW resistors between pins 6, 7 & 8 of IC3 with a dual-gang 1kW logarithmic pot wired as a pair of variable resistors. Pins 6 and 8 of IC3 are current sources, so the voltage signals fed to IC1/IC2 are proportional to these two resistances. Audio player needed with specific functions Can you recommend a media player that will allow me to play a single file on command (via momentary switch) then stop on completion? The next op106 Silicon Chip eration of the switch would play the next file then stop. All the MP3/media players/modules I have looked at will automatically play the next file, which is not what I want. Ideally, once a file is playing, the operation of any switch will not advance to another file. In other words, to play the next file, the previous file must have stopped playing. (W. L., via email) • The easiest way to achieve what you want is probably to modify the software for the Arduino Music Player project (July 2017; siliconchip.com.au/ Article/10722). Alternatively, you could consider using the Stamp-sized Audio Player (December 2018; siliconchip.com. au/Article/11341) which is available from the Silicon Chip Online Shop (Cat SC4789). It can be controlled from either an Arduino or Micromite, and modifying the example software to do what you want should not be too difficult in either case. Why is anti-islanding necessary? I’d like to know how a relatively high source impedance grid-tied inverter can back-feed the mains with its low source impedance. The easy answer customarily given is that the inverter generates a higher voltage; therefore, it feeds the mains. To me, this is like a mini minor trying to push a bulldozer. With lots of UPS and mains-quality monitoring experience, I found that the mains can be quite a hostile environment. Sags, surges, impulses, harmonic distortion, flat-topping and control tones are all quite common. So grid-tied inverters must have lots of smarts to be able to remain synchronised with the mains and adjusting their output to suit. This also leads one to wonder how far this inverter current goes on the mains. Does it just toddle down the lines a little way, or does it go all the way back to the HV transformer? (R. Australia’s electronics magazine C., Peakhurst Heights, NSW) • There could be many inverters feeding the same section of the mains grid and together, their source impedance can be quite low. This is why the local mains voltage can rise above 250V AC on sunny days. Local power generation can be enough to satisfy nearby loads. So if that part of the grid was isolated and there was no anti-islanding provision, it could remain energised for hours. Energy generated by solar systems can travel quite long distances to power remote loads. However, the transformers used in the grid are not designed for bidirectional energy transfer, so this is not terribly efficient. Nearby loads consume most of the energy generated by these systems. Also, keep in mind that the mains source impedance is only low as long as your mains is still connected to the whole grid. Downed power lines or tripped breakers can isolate sections of the mains which may only contain a few premises, or a few dozen, or a few hundred etc. Controlling a stepper motor with an Arduino I want to build a coil winder using a stepper motor to feed wire to the coil that’s being wound. The motor would either be driving a lead screw directly or through gearing (I haven’t decided yet). This motor needs to drive the lead screw over about 50mm, and the number of turns the motor needs to make depends on the pitch of the lead screw thread. After this, the motor will then reverse and repeat the cycle. I want the coil to be layered neatly, and assuming that the coil is wound with 0.2mm diameter wire, each layer will have 250 turns. If the stepper motor is directly coupled to the lead screw shaft, with a thread pitch of 1mm, the stepper motor will need to rotate 50 turns (10,000 steps for 200 steps per rotation). My experience with Arduino is very limited. Can I program the Arduino to siliconchip.com.au drive a stepper motor a set number of steps in one direction, then reverse the rotation for an equal number of steps? I know I will need an indexing input to the Arduino (a photosensor, proximity switch, or another type of sensor) so the Arduino can sense the coil rotation. I can’t find any designs like this online. Many of the existing Arduino sketches seem to use timing for their projects, but I will need to use counting, as the ‘arbour’ that the new coil will be on is (initially) turned by hand, so the rotational speed won’t be consistent. Please pass on my thanks to Jim Rowe for his very interesting articles on stepper motors (February 2019; siliconchip.com.au/Article/11405). It has been these articles that have made me think that using a stepper motor is the right way to do with my project. (P. W., Auckland, NZ) • We have seen Arduino-based coil winding machines, although we can’t find links to any online right now. Many of them use two stepper motors to synchronise the movement of the lead screw and arbour. This might be easier to achieve than counting revolutions. You just need to set a ratio between the two, and keep track of the number of pulses, so you know when to reverse the direction of the lead screw. While your method seems doable, your rotation sensor will need to have a pretty high resolution. Simply having, say, one pulse per rotation would not be adequate; you would ideally need to have a sensor that would give dozens of pulses per rotation. Optical and Hall-effect sensors with such capability are readily available, if not cheap. Keep in mind that the stepper motor will have a maximum rotation speed. So you will need to keep the arbour rotation speed low enough that the stepper can keep up. Perhaps counter-intuitively, it may be both easier and cheaper to build your rig with two motors, rather than having one motor, as its movements would need to be carefully timed to coincide with the measured rotation. Grease for ultrasonic transducer I bought an Ultrasonic Anti-Fouling kit (May & June 2017; siliconchip.com. au/Series/312) from Jaycar, which I besiliconchip.com.au lieve you designed. The instructions say to coat the faces of the encapsulated transducers with a non-hardening grease such as Fix-A-Tap. I’m now in Trinidad and Tobago, and I can’t find the Fix-A-Tap product. Is the medical lubricant for ultrasonic exams a nonhardening grease, and can I use it for anti-fouling? Or can I use silicone grease, liquid paraffin or Vaseline? (P. V, via email) • You can use silicone grease. Medical ultrasonic lubricant is not suitable as it will dry out or dissolve away. Checking ultrasonic transducers I just built your Ultrasonic Cleaner (August 2010; siliconchip.com.au/ Article/244) from an Altronics K6021 kit. I didn’t notice any terminal markings on the transducer, so I soldered the wires onto it and encapsulated it in silicone in the PVC tube before seeing the polarity of the connection in the instructions. If the unit is powered up with the transducer wired the wrong way around, can it do any harm? If not, will I see a noticeable difference in output if the polarity is swapped? How can I measure and verify which wire goes to the centre terminal via the external wiring? Should I be able to measure a specific resistance, capacitance or inductance via the leads going to it? I’m hoping to avoid needing to destroy the PVC tube to access the transducer. (T. J., O’Halloran Hill, SA) • The transducer can be connected with either polarity. There is no difference in output either way, so you don’t need to remove the transducer to check the connection polarity or make any polarity tests. The transducer should measure as a capacitance of about 330nF. The main body of the transducer should be connected to one of the leads, so the resistance between them should measure close to 0W. How to design an alternator or generator I want to design a simple generator using coils of copper wire and permanent magnets. How do I work out the voltage and current it will produce without going to the trouble of building a test rig? The basic design is a bunch of magnets stuck to a steel flywheel that roAustralia’s electronics magazine tates past the wire coils. The internet is full of these types of designs, but they are science-fair type designs or hydroelectric project designs; either too simple or too complicated for me. What I want is a simple formula or (free) software that I can punch in the magnet flux values, wire gauge, wire length, number of turns, wire resistance, magnet speed etc and get an idea of the expected voltage and current delivery. I want to be able to tailor the output voltage and current to something like 12V and 1A at 3600RPM. I don’t mind doing the work, I just can’t find the information easily. (A. P., Wodonga, Vic) • The following website has a calculator that will tell you the expected voltage: siliconchip.com.au/link/aax6 The amount of power that can be generated (from which you can infer the current) is related to the amount of power provided by the force causing the rotation and generator efficiency. The wire gauge and resistance are inter-related and determine the amount of current that can be generated, limited by either the voltage drop and/or melting the wire. The wire gauge and resistance do not affect the generated voltage until there is a load applied to cause current flow. You can get more information on the topic from these links: siliconchip.com.au/link/aax3 siliconchip.com.au/link/aax4 siliconchip.com.au/link/aax5 AM Demodulator Probe diode repeatedly failing Some time ago, I built the Audio Injector and Tracer (June 2015; siliconchip.com.au/Article/8603) by John Clarke, from an Altronics kit. I also built the AM Demodulator Probe described in the same issue. I am very happy with both but have had to change the BAT46 diode in the Demodulator on two occasions after fault-finding valve radios. The diode fails by going leaky in the reverse direction. Is there another diode that I could use that could handle a larger DC voltage with similar sensitivity? I should mention that I have used a 2kV 100pF input capacitor, and there is no leakage in the capacitor, tested at 500V DC with one of your insulation testers. (P. W., Montmorency, Vic) • There are not many other suitable diodes for RF detection that have a December 2019  107 high reverse breakdown voltage. The BAT46 has a reverse breakdown voltage rating of 100V. The diode is probably failing due to the momentary surge current through the input 100pF capacitor, diode D1 and 1nF filter capacitor to ground when probing high voltage points in the circuit. You could include a 2kW resistor in series with the BAT46 to reduce the surge current. This may prevent the diode from going leaky. Alternatively, though not intended for RF detection, a BAT240 diode may be suitable, given that it has a low capacitance and low forward voltage drop. This has a reverse breakdown rating of 250V. The package includes two diodes in the SOT-23 SMD package. This could be wired into the Probe board with tinned copper wire to extend the connections between the diode pins and the PCB. Increasing Deluxe Fan Speed Controller power Is it possible to increase the power-handling capacity of the Deluxe 230VAC Fan Speed Controller (May 2014; siliconchip.com.au/ Article/7595) from 60W to 120W by paralleling the power device with another identical transistor? I’m not sure, however, how to adequately heatsink the pair of transistors. (E. McA., Capel, WA) • It is possible to parallel the Mosfets, but they will not necessarily share the load equally, as the resistance versus gate voltage curve will not necessar- ily be evenly matched between the two devices. If you’re going to try it, you should use Mosfets from the same batch to improve the chance of having a close match. The second Mosfet would need to be mounted against the side of the case for heatsinking. The existing case and heatsink should be adequate to dissipate the extra heat. You would also need to reduce the 1W current-sensing resistor to 0.47W 5W. Note also that we originally rated the controller at 80W maximum and that is a conservative figure. High-impedance piezo preamp for violin I recently purchased a Fishman V-200 piezo pickup for my violin. The instructions say it should work OK when plugged into a high-impedance preamp and suggested an input impedance of 1MW is sufficient. They suggest several commercial products, all with around 10MW input impedances. I am using it with your March 2002 Mighty Midget amplifier (siliconchip. com.au/Article/4091) and a guitar preamplifier described in Electronics Australia or ETI many years ago. Sorry, I can’t remember when it was published. It works well enough, but the 2-tone controls are a bit limiting. I also built one of your microphone preamps (September 2010; siliconchip.com.au/Article/283), but that has an input impedance of just 50kW, which is probably a bit too low. Is there any way to increase its imped- ance? Or do you have any other suggestions? Ideally for the violin, I would like to have treble and bass controls, plus parametric equalisation similar to the ETI-1424 design. It would also be very useful if it had a foot-switch-controlled preset volume boost to use when playing solos. I have the ETI-1424 and could cobble together the volume boost. I just need your help with the preamp. (B. L., Cranbourne South, Vic) • You could use the input stage of the JFET Guitar Preamp (Circuit Notebook, September 2018; siliconchip.com.au/ Article/11238). The signal from the drain of JFET Q1 could then feed into whatever circuitry that you need, such as the ETI-1424 guitar preamplifier. You don’t need all the following circuitry to emulate the valve sound. Designing parabolic audio reflectors I have almost completed a sort-of copy of the audio reflector that was published in Electronics Australia, November 1983. I notice that it is much deeper than the commercially available dishes like the Telinga. The dish I built is made from roughly 1mm-thick flexible acrylic sheet, as sold at places like Bunnings. It needs some bracing to make it more rigid, and the 300 cable ties holding it together make it look a bit home-made. But in another week or so I should have the microphone insert and preamp installed so we can see how well, or poorly, it works. More output transistors won’t lower amplifier’s output impedance During my career, I dealt with ultra-high-precision magnetic CRT deflection amplifiers. These were used for medical imaging purposes, and the grapevine from the factory said they made brilliant audio amps. They delivered current into a very low impedance reactive load. Consequently, they used multiple parallel output stages. While able to deliver the required current, the configuration also gave very low reflective impedance and hence control to a highly reactive inductive load. Both your SC200 (JanuaryMarch 2017; siliconchip.com.au/ Series/308) and Ultra-LD series of 108 Silicon Chip amplifiers (August-October 2015; siliconchip.com.au/Series/289) use double parallel output stages for power handling reasons. Would adding an extra output pair improve cone control, particularly when used for large woofer speaker applications? Cone control, which is a source of distortion, is a difficult parameter to measure at home without advanced test equipment. (K. J., Kingston, Tas) • As Douglas Self points out in his books on audio amplifiers, the determining factor in the output impedance of most power amplifiers is in the RLC filter required for stability. Australia’s electronics magazine The filter impedance is kept low at audio frequencies by using the lowest practical inductance value, along with the thickest practical wire. All our recent amplifier designs have a very low output impedance (ie, a high damping factor) and provide very good cone control. Adding more output transistor pairs will have a minimal effect. We reviewed Self’s Audio Power Amplifier Design Handbook in the March 2010 issue (siliconchip.com. au/Article/89). We consider this a ‘must-have’ book for anyone seriously interested in audio amplifier design. siliconchip.com.au SILICON CHIP .com.au/shop ONLINESHOP PCBs, CASE PIECES AND PANELS DIODE CURVE PLOTTER FLIP-DOT (SET OF ALL FOUR PCBS) iCESTICK VGA ADAPTOR UHF DATA REPEATER AMPLIFIER BRIDGE ADAPTOR 3.5-INCH SERIAL LCD ADAPTOR FOR ARDUINO DSP CROSSOVER/EQUALISER ADC BOARD DSP CROSSOVER/EQUALISER DAC BOARD DSP CROSSOVER/EQUALISER CPU BOARD DSP CROSSOVER/EQUALISER PSU BOARD DSP CROSSOVER/EQUALISER CONTROL BOARD DSP CROSSOVER/EQUALISER LCD ADAPTOR DSP CROSSOVER (SET OF ALL BOARDS – TWO DAC) STEERING WHEEL CONTROL IR ADAPTOR GPS SPEEDO/CLOCK/VOLUME CONTROL GPS SPEEDO ACRYLIC CASE PIECES (MATTE BLACK) RF SIGNAL GENERATOR RASPBERRY PI SPEECH SYNTHESIS/AUDIO BATTERY ISOLATOR CONTROL BOARD BATTERY ISOLATOR MOSFET BOARD (2oz) MAR 2019 APR 2019 APR 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 MAY 2019 JUNE 2019 JUNE 2019 JUNE 2019 JUNE 2019 JULY 2019 JULY 2019 JULY 2019 04112181 SC4950 02103191 15004191 01105191 24111181 01106191 01106192 01106193 01106194 01106195 01106196 SC5023 05105191 01104191 SC4987 04106191 01106191 05106191 05106192 $7.50 $17.50 $2.50 $10.00 $5.00 $5.00 $7.50 $7.50 $5.00 $7.50 $5.00 $2.50 $40.00 $5.00 $7.50 $10.00 $15.00 $5.00 $7.50 $10.00 MICROMITE LCD BACKPACK V3 CAR RADIO DIMMER ADAPTOR/VOLTAGE INTERCEPTOR PSEUDO-RANDOM NUMBER GENERATOR (LFSR) 4DoF SIMULATION SEAT CONTROLLER BOARD HIGH-CURRENT H-BRIDGE MOTOR DRIVER MICROMITE EXPLORE-28 (4-LAYERS) SIX INPUT AUDIO SELECTOR MAIN BOARD SIX INPUT AUDIO SELECTOR PUSHBUTTON BOARD ULTRABRITE LED DRIVER HIGH RESOLUTION AUDIO MILLIVOLTMETER PRECISION AUDIO SIGNAL AMPLIFIER SUPER-9 STEREO FM RADIO (SET OF ALL PCBS REQ.) SUPER-9 CASE PIECES & DIAL (BLACK / CLEAR) TINY LED XMAS TREE (CHOICE OF GREEN/RED/WHITE) HIGH POWER LINEAR BENCH SUPPLY LINEAR BENCH SUPPLY HEATSINK SPACER (BLACK) FIVE-WAY LCD PANEL METER / USB DISPLAY LCD PANEL METER BEZEL (BLACK) NEW THIS MONTH UNIVERSAL BATTERY CHARGE CONTROLLER AUG 2019 AUG 2019 AUG 2019 SEPT 2019 SEPT 2019 SEPT 2019 SEPT 2019 SEPT 2019 SEPT 2019 OCT 2019 OCT 2019 NOV 2019 NOV 2019 NOV 2019 NOV 2019 NOV 2019 NOV 2019 NOV 2019 DEC 2019 07106191 05107191 16106191 11109191 11109192 07108191 01110191 01110192 16109191 04108191 04107191 06109181-5 SC5166 16111191 18111181 SC5168 18111182 SC5167 $7.50 $5.00 $5.00 $7.50 $2.50 $5.00 $7.50 $5.00 $2.50 $10.00 $5.00 $25.00 $25.00 $2.50 $10.00 $5.00 $2.50 $2.50 14107191 $10.00 PRE-PROGRAMMED MICROS As a service to readers, Silicon Chip Online Shop stocks microcontrollers and microprocessors used in new projects (from 2012 on) and some selected older projects – pre-programmed and ready to fly! Some micros from copyrighted and/or contributed projects may not be available. ATtiny816 PIC12F202-E/OT PIC12F617-I/P PIC12F675-E/P PIC12F675-I/P PIC12F675-I/SN PIC16F1455-I/P PIC16F1459-I/P PIC16F88-E/P PIC16F88-I/P PIC16LF88-I/P $10 MICROS ATtiny816 Development/Breakout Board (Jan19) Ultrabrite LED Driver (with free TC6502P095VCT IC, Sept19) Temperature Switch Mk2 (June18), Recurring Event Reminder (Jul18) Door Alarm (Aug18), Steam Whistle (Sept18) White Noise (Sept/Nov18) Remote Control Dimmer (Feb19), Steering Wheel Control IR Adaptor (Jun19) Car Radio Dimmer Adaptor / Voltage Interceptor (Aug19) Courtesy LED Light Delay for Cars (Oct14), Fan Speed Controller (Jan18) Kelvin the Cricket (Oct17), Triac-based Mains Motor Speed Controller (Mar18) Heater Controller (Apr18), Useless Box IC3 (Dec18) Tiny LED Xmas Tree (Nov19) Microbridge & BackPack V2 / V3 (May17 / Aug19), USB Flexitimer (June18) Digital Interface Module (Nov18), GPS Speedo/Clock/Volume Control (Jun19) Five-Way LCD Panel Meter / USB Display (Nov19) Auto Headlight Controller (Oct13), 10A 230V Motor Speed Controller (Feb14) Automotive Sensor Modifier (Dec16) Cyclic Pump Timer (Sep16), 60V 40A DC Motor Speed Controller (Jan17) Pool Lap Counter (Mar17), Rapidbrake (Jul17), Deluxe Frequency Switch (May18) Useless Box IC1 (Dec18), Remote-controlled Preamp with Tone Control (Mar19) UHF Repeater (May19), Six Input Audio Selector (TWO VERSIONS, Sept19) Universal Battery Charge Controller (Dec19) Garbage Reminder (Jan13), Bellbird (Dec13), GPS Analog Clock Driver (Feb17) ATmega328P PIC16F1459-I/SO PIC16F877A-I/P PIC32MM0256GPM028-I/SS PIC32MX170F256D-501P/T PIC32MX170F256B-50I/SP PIC32MX270F256B-50I/SP PIC32MX470F512H-I/PT PIC32MX470F512H-120/PT PIC32MX470F512L-120/PT dsPIC33FJ128GP802-I/SP PIC32MZ2048EFH064-I/PT $15 MICROS RF Signal Generator (Jun/Jul19) Four-Channel DC Fan & Pump Controller (Dec18) 6-Digit GPS Clock (May-Jun09), 16-bit Digital Pot (Jul10), Semtest (Feb-May12) Super Digital Sound Effects (Aug18) 44-pin Micromite Mk2 (Aug14), 4DoF Simulation Seat (Sept19) Micromite Mk2 (Jan15) + 47F, Low Frequency Distortion Analyser (Apr15) GPS Boat Computer (Apr16), Micromite Super Clock (Jul16) Touchscreen Voltage/Current Ref (Oct-Dec16), Deluxe eFuse (Aug17) Micromite DDS for IF Alignment (Sept17), Tariff Clock (Jul18) GPS-Synched Frequency Reference (Nov18) ASCII Video Terminal (Jul14), USB Mouse & Keyboard Adaptor (Feb19) $20 MICROS Stereo Audio Delay/DSP (Nov13), Stereo Echo/Reverb (Feb 14) Digital Effects Unit (Oct14) Micromite PLUS Explore 64 (Aug 16), Micromite Plus LCD BackPack (Nov16) Micromite PLUS Explore 100 (Sep-Oct16) Digital Audio Signal Generator (Mar-May10), Digital Lighting Cont. (Oct-Dec10) SportSync (May11), Digital Audio Delay (Dec11) Quizzical (Oct11), Ultra-LD Preamp (Nov11), LED Musicolor (Nov12) $30 MICROS DSP Crossover/Equaliser (May19) SPECIALISED COMPONENTS VARIOUS MODULES & PARTS - I/O expander modules: PCA9685 – $6.00 ~ PCF8574 – $3.00 ~ MCP23017 – $3.00 (NOV19) - SMD 1206 LEDs (Tiny LED Xmas Tree, NOV19): 10 yellow – $0.70 ~ 10 amber – $0.70 ~ 10 blue – $0.70 ~ 10 cyan – $1.00 ~ 1 pink – $0.20 - ISD1820-based voice recorder / playback module (Junk Mail Repeller, AUG19) $4.00 - 23LCV1024-I/P SRAM (DIP) and MCP73831T charger ICs (UHF Repeater, MAY19) $11.50 - MCP1700 3.3V LDO regulator (suitable for USB Mouse & Keyboard Adapator, FEB19) $1.50 - LM4865MX amplifier IC & LF50CV regulator (Tinnitus/Insomnia Killer, NOV18) $10.00 - 2.8-inch touchscreen LCD module with SD card socket (Tide Clock, JUL18) $22.50 - ESP-01 WiFi Module (El Cheapo Modules, Part 15, APR18) $5.00 - MC1496P double-balanced mixer IC (DIP-14) (AM Radio Transmitter, MAR18) $2.50 - WiFi Antennas with U.FL/IPX connectors (Water Tank Level Meter with WiFi, FEB18): 5dBi – $12.50 ~ 2dBi (omnidirectional) – $10.00 - NRF24L01+PA+NA transceiver with SNA connector and antenna (El Cheapo 12, JAN18) $5.00 - WeMos D1 Arduino-compatible boards with WiFi (SEPT17, FEB18): ThingSpeak data logger – $10.00 ~ WiFi Tank Level Meter (ext. antenna socket) – $15.00 - ERA-2SM+ MMIC & ADCH-80A+ choke (6GHz+ Frequency Counter, OCT-DEC17) $15.00 - Geeetech Arduino MP3 shield (Arduino Music Player/Recorder, VS1053, JUL17) $20.00 - 1nF 1% MKP (5mm lead spacing) or ceramic capacitor (Wide-Range LC Meter, JUN18) $2.50 - MAX7219 LED controller boards (El Cheapo Modules, Part 7, JUN17): 8x8 red SMD/DIP matrix display – $5.00 ~ red 8-digit 7-segment display – $7.50 - AD9833 DDS module (with gain control) (for Micromite DDS, APR17) $25.00 - AD9833 DDS module (no gain control) (El Cheapo Modules, Part 6, APR17) $15.00 - CP2102 USB-UART bridge $5.00 - microSD card adaptor (El Cheapo Modules, Part 3, JAN17) $2.50 - DS3231 real-time clock module with mounting spacers and screws (El Cheapo, OCT16) $5.00 SUPER-9 FM RADIO - CA3089E IC, DIP-16 (SC5164) - MC1310P IC, DIP-14 (SC4683) - 110mm telescopic antenna (SC5163) - Neosid M99-073-96 K3 assembly pack (two required) (SC5205) (NOV 19) $3.00 $5.00 $7.50 $6.00 ec. TINY LED XMAS TREE COMPLETE KIT (SC5180) (NOV 19) Includes PCB, micro, CR2032 cell, holder and all other parts. Also includes 12 red, 12 green & 12 white LEDs plus four extra 100W resistors. PCB available in three colours (green, red or white). $15.00 MICROMITE EXPLORE-28 (CAT SC5121) Complete kit – includes PCB plus programmed micros and all other onboard parts Programmed micro bundle – PIC32MX170F256B-50I/SO + PIC16F1455-I/SL (SEPT 19) $30.00 $20.00 MICROMITE LCD BACKPACK V3 (CAT SC5082) (AUG 19) KIT – includes PCB, programmed micros, 3.5in touchscreen LCD, laser-cut UB3 lid, mounting hardware, SMD Mosfets for PWM backlight control and all other mandatory on-board parts Separate/Optional Components: - 3.5-inch TFT LCD touchscreen (Cat SC5062) - DHT22 temp/humidity sensor (Cat SC4150) - BMP180 (Cat SC4343) OR BMP280 (Cat SC4595) temperature/pressure sensor - BME280 temperature/pressure/humidity sensor (Cat SC4608) - DS3231 real-time clock SOIC-16 IC (Cat SC5103) - 23LC1024 1MB RAM (SOIC-8) (Cat SC5104) - AT25SF041 512KB flash (SOIC-8) (Cat SC5105) - 10µF 16V X7R through-hole capacitor (Cat SC5106) $75.00 $30.00 $7.50 $5.00 $10.00 $3.00 $5.00 $1.50 $2.00 $10 flat rate for postage within Australia. Overseas? Place an order via our website for a quote. All items subect to availability. Prices valid for month of magazine issue only. All prices in Australian dollars and included GST where applicable. PAYPAL (24/7) Australia’s electronics INTERNET (24/7) MAIL (24/7) PHONE – 2019  109 (9-4:30, Mon-Fri) eMAIL (24/7) To siliconchip.com.au magazine December Use your PayPal account siliconchip.com.au/Shop Your order to PO Box 139 Call (02) 9939 3295 with silicon<at>siliconchip.com.au Place silicon<at>siliconchip.com.au Collaroy NSW 2097 with order & credit card details Your You can also order and pay by cheque/money order (Orders by mail only). Make cheques payable to Silicon Chip Publications. Order: 12/19 Coming back to the depth of the dish, there isn’t all that much info available on the design of these reflectors when used for sound. Is a copy of the article by G. N. Patchett from EA, October 1973 titled “Tests on parabolic reflectors” available? It would be interesting to compare the performance of shallower dished reflectors with the design published in 1983. (D. H., Lower Pappinbarra, NSW) • Our tests when building this type of reflector show that the deeper the dish, the better it prevents the intrusion of other sounds apart from the ones it is pointing directly at. A true parabola shape would make the received sound more intense, but even a straight-sided ‘reflector’ can be effective with the microphone placed at the rear. We don’t already have a scan of the Electronics Australia article you mentioned from October 1973, but as with any other EA article, you can request a scan or photocopy via our website by going to siliconchip.com. au/Shop/15 10W stereo amplifier with 4W speakers Back in about 1967/8 I built the Electronics Australia 10+10 stereo amplifier. It used four 6GW8 valves. I still have the amplifier and preamp, and I would like to restore it with new capacitors etc. The speaker cabinets I built for it are long gone. I have a couple of commercial speakers, but they have 4W impedances. Can I use those with this amplifier? (P. C., Balgal Beach, Qld) • That would be the Playmaster 101, designed by John Davidson and Neville Williams and published in the August 1962 issue of Radio, TV & Hobbies (pages 73-79). The output transformers have multi-tapped primaries and secondaries. The original design was for 15W speakers, but there are taps on the secondaries for 8W, 3.7W and 2W speakers. So if you switch your connections from the 15W taps to the 3.7W taps, it should have no problems driving modern 4W loudspeakers. How to set up the Flexitimer I bought a Flexitimer kit (Jaycar Cat KA1732; EA March 1991) and need help setting it up. I bought it to oper110 Silicon Chip ate as a delay circuit for a car wiper intermittent control (my vehicle didn’t come out with one). I need the relay to be on for one second and then off for 3-20 seconds, repeating, or off for one second and on for 3-20 second, repeating. Looking at the circuit, I may need to use the 4020 as my timer control, not RV1, so I would use the 12-position rotary switch as my timer control. Can you give me approximate values for R1, RV1, R2, C1 and any other relevant components, if this is possible? • That kit is based on the Electronics Australia Flexitimer from their March 1991 issue, with extra circuitry based on our relevant Circuit Notebook contributions. To achieve your goals, R1 should be 33kW, RV1 a 200kW trimpot, R2 10kW and C1 100µF. The relay will then be on for 3-20s (adjusted with RV1) and off for one second (set by R2). The 4020 output is not needed. Instead, the connection is from pin 3 of IC1 (the 555 timer) to the base of Q1 via R4. High-Energy Ignition vs Programmable Ignition I’m interested in tinkering with your Programmable Electronic Ignition System for Cars (March-May 2007; siliconchip.com.au/Series/56). I bought the main PCB and relevant back-issues from your Online Shop, and managed to snap up the last Ignition Coil Driver kit from Jaycar (Cat KC5442). How does the performance of this unit differ from your High-Energy Ignition System (November-December 2012; siliconchip.com.au/Series/18)? Is there any advantage in modifying the earlier design to use an IGBT? Would that result in more energetic sparks? (R. F., Somerset, Tas) • The spark energy is related to the ignition coil itself, the dwell time and also to some extent the driver transistor, as losses across this can affect spark energy. The High-energy Ignition System and Programmable Ignition System will deliver a similar spark using the same coil and dwell time. You can modify the coil driver by changing the Darlington transistor to an IGBT, which reduces the power consumption of the ignition system and greatly simplifies the coil driver. Australia’s electronics magazine How to do this was explained on page 68 of the June 2013 issue (siliconchip. com.au/Article/3826) But this probably won’t significantly increase the spark energy. Electronic Ignition has inconsistent spark I built the Electronic Ignition System from the November & December 2012 issues (siliconchip.com.au/Series/18). My setup is identical to the Hall Effect switch layout shown in the article, including the mounting of the IGBT. The initial tests were all as expected. However, when the complete system is run without links, the first spark is about 8mm long and the second spark is about 1mm long or absent. This is regardless of which of the four trigger blades is first to pass the switch. I used a steel ruler as a trigger with the same result. The subsequent sparks alternate strong and weak. I replaced the PIC controller, the low-dropout regulator but not the IGBT. I have used various coils, which all have the correct primary and secondary resistances, and with and without a ballast resistor, as indicated by the coil specs. All to no avail. Can you help? (R. R., South West Rocks, NSW) • The spark test with LK2 in will show whether the coil sparks correctly each time, rather than alternately strong and weak. We think that the triggering method you are using is causing the problem. Are you testing triggering via the Hall effect unit by rotating the blade through the Hall effect sensor by hand, rather than by using the engine or starter motor? You can expect poor spark performance if the hall effect trigger rate is not regular. That is because the dwell time (the period for charging the coil) is based on an RPM calculation that is reliant on a steady trigger rate. The dwell period begins before the Hall Effect unit provides a trigger signal. The dwell starting point is calculated and provided to give the required dwell period before the next trigger point. A steady trigger rate is present for engine or during starter motor triggering rates, but not when the trigger is irregular like when turned by hand or via the movement of a steel ruler. If that is the case, try testing the ignition system on the vehicle. SC siliconchip.com.au MARKET CENTRE Cash in your surplus gear. Advertise it here in SILICON CHIP KIT ASSEMBLY & REPAIR PCB PRODUCTION FOR SALE 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 PCB MANUFACTURE: single to multi­ layer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au BUSINESS FOR SALE Well known Australian electronics company for under $50,000. GENUINE BUYERS ONLY Phone: 0410600330 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 MISCELLANEOUS LOOKING FOR: Set of Dick Smith Electronics catalogues from 1975-1982. Must be in pristine condition. Will pay $200 for the set (inc. postage), only one set needed. Contact Melanie (on behalf of inquirer on 02 8832 3100) tronixlabs.com.au – Australia’s best value for supported hobbyist electronics from your favourite brands – along with kits, components and much more – with flat-rate $9 delivery Australia-wide. LEDs, BRAND NAME and generic LEDs. Heatsinks, fans, LED drivers, power supplies, LED ribbon, kits, components, hardware, EL wire. www.ledsales.com.au ASSORTED BOOKS FOR $5 EACH Selling assorted books on electronics and other related subjects like audio, video, programming etc. Many of them are in poor condition. Some of the books may not be for sale, but the vast majority are available. Bulk discount available; post or pickup. All books can be viewed at: siliconchip.com.au/link/aawx Silicon Chip silicon<at>siliconchip.com.au 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 2019  111 Coming up in Silicon Chip A Complete DCC System for Model Trains Advertising Index This Arduino-based system uses one or two simple shields which have everything you need to run a small or medium-sized DCC-based model railway layout. It’s expandable and operates with the open-source DCC++ and JMRI software. Altronics...............................81-84 Emergency Backup Power Control Devices......................... 11 Are you prepared for an extended blackout? Most households aren’t, but there are a few relatively inexpensive options for keeping the lights (and fridge, and TV...) on, even when everyone else’s are out. Dave Thompson...................... 111 Tuneable HF Preamplifier Many low-cost SDR modules have poor HF (3-30MHz) performance. Their wideopen front ends also make them susceptible to cross-modulation from strong signal sources. This simple tuneable preamp greatly improves SDR HF performance. It has adjustable gain control and can run off a 5V supply or phantom power. Korg Nutube Preamplifier This compact and classy preamp uses an unusual device: the Kord 6P1 ‘Nutube’ twin triode, which was released in 2017! Yes, this is a new valve, and it’s unlike anything you’ve ever seen before. Note: these features are planned or are in preparation and should appear within the next few issues of Silicon Chip. The January 2020 issue is due on sale in newsagents by Monday, December 30th. Expect postal delivery of subscription copies in Australia between December 23rd and January 10th. Notes & Errata Super-9 FM Radio, November 2019: in the circuit diagram (Fig.4, pp32-33), the 4.7pF capacitor above and to the right of Q4 actually connects to Q4’s base, not its emitter. This signal is 10.7MHz above the tuned station, not fixed at 10.7MHz. Also, the 10nF capacitor shown connected between pin 13 of IC3 and ground is not present on the PCB, and not needed. Finally, the text refers to VREF from pin 10 of IC3 being applied to the anode of VC3, but it actually goes to the cathode. Shunt regulator for wind turbines, Circuit Notebook, November 2019: the drain and source of Q9 have been reversed. Q9 is not used for reverse polarity protection, but instead to regulate the supply voltage to IC1 and for the fan, to around 12V. Arduino-based Digital Audio Millivoltmeter, October 2019: in the circuit diagram (Fig.3) and PCB overlay (Fig.5), the 220nF capacitor between pin 3 of IC3 and pin 4 (GND) should be a 1µF 50V through-hole ceramic or MKT as in the parts list. The overlay incorrectly labels the PCB as 04106191 when it should be 04108191. The PCBs we sell have all these correctly marked on the silkscreen. Micromite Explore-28, September 2019: in Fig.4 on page 56, the pinout shown for REG1 is incorrect. Pin 1 is the input (IN) while pin 2 and the tab connect to GND. Full Wave 230V 10A Universal Motor Speed Controller, March 2018: a bug in the original software (1010218A) prevents the feedback speed control from working after the soft-start period. Revised software (1010218B) is available online. In the circuit diagram (Fig.1), the electrolytic capacitor connected to the junction of the 10kW and 1kW resistors to the left of diode D5 should be 10µF, not 100µF. Some PCBs sold may also show this capacitor as 100µF but the overlay diagram, Fig.2, shows the correct value of 10µF. VR2 is also shown as 1kW in the circuit, but should be 10kW as in the parts list and overlay. Stationmaster, March 2017: in the circuit diagram (Fig.2) on page 36, brake switch S1 should have been shown connected between potentiometer VR3 and the 10kW resistor, with the second pin of CON5 from the top connecting to the junction of VR3 and switch S1. 112 Silicon Chip Australia’s electronics magazine Ampec Technologies................. 37 Digi-Key Electronics.................... 3 Elf Electronics........................... 12 Embedded Logic Solutions....... 49 Emona..................................... IBC Hare & Forbes....................... OBC Hi-Q Components NZ.................. 4 Jaycar............................ IFC,53-60 Keith Rippon Kit Assembly...... 111 LD Electronics......................... 111 LEACH PCB Assembly............. 75 LEDsales................................. 111 Microchip Technology.................. 9 Mouser Electronics...................... 5 Oatley Electronics................... 105 Ocean Controls........................... 8 PCB Global............................... 12 RayMing PCB & Assembly........ 10 Rohde & Schwarz........................ 7 Silicon Chip Subscriptions....... 52 Silicon Chip Shop............. 23,109 Silicon Chip Wallchart.............. 36 The Loudspeaker Kit.com......... 13 Tronixlabs................................ 111 Vintage Radio Repairs............ 111 Wagner Electronics..................... 6 siliconchip.com.au “Rigol Offer Australia’s Best Value Test Instruments” Oscilloscopes FREE OPTIONS Bundle! New Product! 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