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The VERY BEST DIY Projects! Built-in Wi-Fi (NTP) support » 62 addressable RGB LEDs » Can be configured remotely » NeoPixel RGB LED Analog Clock Portable EMF Probe Ideal Bridge Rectifiers for Power Amplifiers NOVEMBER 2026 ISSN 1030-2662 11 9 771030 266001 $1500* NZ $1590 INC GST INC GST THE NEW 2026/27 JAYCAR CATALOGUE IS HERE Loaded with our latest products, the new 2026/27 Jaycar Engineering & Scientific Catalogue brings 612 pages of tech, electronics, components and tools together in one place. Keep it on the workbench for easy browsing, comparison and inspiration. Sometimes it’s better to flick than click. O N LY 9 $ 95 ^ The catalogue will be available for purchase from our stores or online. Prefer digital? A convenient flipbook version will also be available online. www.jaycar.com.au | www.jaycar.co.nz Australia New Zealand BJ5000: $9.95 BJ5002: $11.90 Scan the QR Code or visit: AU: jaycar.com.au/p/BJ5000 NZ: jaycar.co.nz/p/BJ5002 Limited print run. Be quick before they sell out! ^Price Shown in $AUD - NZ price is $11.90 Contents Vol.39, No.11 November 2026 12 The History of AMD, Part 1 AMD, like Intel, has a long history of making computer CPUs for the consumer market, including the first 64-bit offerings. In this three-part series, we look at what made AMD one of the largest tech companies in the world. By Dr David Maddison, VK3DSM Electronics feature The History of AMD Part 1 Page 12 46 Motor Control, Part 2 This series will cover many of the different motor types in depth, looking at how they work and can be controlled. This month, we will look at brushless DC motors and permanent-magnet synchronous motors. By Andrew Levido Electronics theory 58 Microchip’s VS Code IDE Microchip has released an MPLAB extension for Visual Studio Code, acting as a replacement for their MPLAB IDE. We take a look at what you can do with it, and also some of the new chips Microchip have on offer. Review by Tim Blythman Software development feature 92 Bass Guitar Valve Amplifier Fred Lever decided to design a 1970s style all-in-one bass guitar amplifier but kept it light for easy portability. He also describes building and customising a matching bass guitar from a Pit Bull kit. Br Fred Lever Vintage Electronics 26 NeoPixel RGB LED Analog Clock This updated version of our ‘Analog’ Clock brings in a new white PCB, and some interesting features. It has built-in Wi-Fi and NTP support, can be configured remotely and uses addressable RGB LEDs. Part 1 by Nicholas Vinen Clock project 52 Portable EMF Probe Our EMF Probe uses a single inductor to detect electromagnetic fields (EMF) and converts them into audio. It can be used to troubleshoot faulty switchmode power supplies, or even just as an educational tool. By Tim Blythman Test equipment project 66 Ideal Bridge Rectifiers With four different PCB configurations using SMD or through-hole parts, these bridge rectifiers are ideal for dual-rail power supplies from 5V to 50V AC in and up to 20A continuous load currents, like power amps. By Phil Prosser Power supply project 75 Mighty USB-C Bench Supply By using USB Power Delivery (USD-PD), you can build your own adjustable power supply that can deliver up to 20V at 2A. In this final part we cover the construction details, plus how to set it up and use it. Part 2 by Tim Blythman Power supply project Page 66 Ideal Bridge Rectifier 2 Editorial Viewpoint 4 Mailbag 43 Circuit Notebook 83 Kits 84 Serviceman’s Log 90 Online Shop 101 Ask Silicon Chip 103 Market Centre 104 Advertising Index 104 Notes & Errata 1. Long delay timer 2. Identifying objects using YOLOE 3. Formaldehyde gas monitor 4. Feeding line level audio to a mic input SILICON SILIC CHIP www.siliconchip.com.au Publisher/Editor Nicholas Vinen Technical Editor John Clarke – B.E.(Elec.) Technical Staff Bao Smith – B.Sc. Tim Blythman – B.E., B.Sc. Advertising Enquiries (02) 9939 3295 adverts<at>siliconchip.com.au Regular Contributors Allan Linton-Smith Dave Thompson David Maddison – B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Geoff Graham Associate Professor Graham Parslow Dr Hugo Holden – B.H.B, MB.ChB., FRANZCO Ian Batty – M.Ed. Phil Prosser – B.Sc., B.E.(Elec.) Cartoonist Louis Decrevel loueee.com Founding Editor (retired) Leo Simpson – B.Bus., FAICD Silicon Chip is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 626 922 870. ABN 20 880 526 923. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Subscription rates (Australia only) 6 issues (6 months): $77.50 12 issues (1 year): $145 24 issues (2 years): $270 Online subscription (Worldwide) 6 issues (6 months): $55 12 issues (1 year): $105 24 issues (2 years): $200 For overseas rates, see our website or email silicon<at>siliconchip.com.au * recommended & maximum price only Postal address: PO Box 194, Matraville, NSW 2036. Phone: (02) 9939 3295. ISSN: 1030-2662 Printing and Distribution: 1 Huntingwood Dr, Huntingwood NSW 2148 54 Park St, Sydney NSW 2000 2 Silicon Chip Editorial Viewpoint AI is reshaping computer security Love or hate AI, as I predicted in May 2023, it is having a significant impact on the world. I will admit that I didn’t mention computer security as an area where the impact would be disproportionate, but that seems to be the case. AI systems are becoming remarkably good at reviewing source code, analysing program behaviour and looking for mistakes that human programmers and security researchers have overlooked. That is potentially a very good thing. Modern software is extraordinarily complicated. An operating system such as Windows or Linux contains tens of millions of lines of code and has accumulated contributions over decades. No human being could possibly read and understand all of it, while conventional automated tools are generally limited to looking for particular classes of errors. AI changes that equation because it can examine huge quantities of code and reason about the way different pieces interact. It can also generate test cases, investigate suspicious behaviour and increasingly determine whether an apparent bug is actually exploitable. This is no longer hypothetical. Microsoft’s new MDASH security system found 16 vulnerabilities that were fixed in its May 2026 Windows updates. Four of those were rated critical and could allow remote code execution. Google’s Big Sleep AI system has similarly discovered vulnerabilities in widely used software, including an exploitable memory-safety bug in SQLite. The scale is becoming enormous. VulnCheck found that CVE (Common Vulnerabilities and Exposures) disclosures were sharply higher across numerous major software suppliers during 2026, including Chrome, Mozilla, Apache, VMware and others. Finding bugs is becoming so easy that they’re being found quicker than they can be fixed. Anthropic’s Project Glasswing (started in April this year) picked up more than 23,000 potential bugs; only a fraction had been reported to software maintainers by June. Someone has to determine whether each bug report is genuine, work out which versions are affected, develop and test a fix and distribute it without introducing another problem. Software maintainers are becoming inundated. Open-source developers have already complained about large numbers of AI-generated security reports. Some are nonsense; false reports waste resources, too. In May, Google’s Threat Intelligence Group reported what it believes was the first observed case of a threat actor using a zero-day exploit developed with the assistance of AI. Anthropic reported last year that a state-sponsored espionage group had manipulated Claude Code into helping attack roughly 30 organisations. A small number of the attacks succeeded. In a sense, we have entered a new race between the ‘white hats’ finding and fixing vulnerabilities and the ‘black hats’ finding and exploiting them. Still, of the 1061 vulnerabilities that VulnCheck identified as having been discovered with AI assistance in the first half of this year, only 14 had been confirmed as exploited in the wild. So AI has unquestionably caused an explosion in finding vulnerabilities, but there is not yet evidence of a corresponding explosion in successful attacks. In the longer term, we should end up with more secure software. In the short term, though, we have a vast stockpile of existing software being examined simultaneously by increasingly capable machines on both sides. While AI won’t inevitably make computer security worse, it has dramatically increased the speed at which both sides can operate. It reminds me of the saying usually described as an ancient Chinese curse: “May you live in interesting times”. We certainly do. Cover background image: https://unsplash.com/photos/green-and-red-light-digital-wallpaper-bEd5KVP5b4g Australia's electronics magazine by Nicholas Vinen 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 has the right to edit, reproduce in electronic form, and communicate these letters. This also applies to submissions to “Ask Silicon Chip”, “Circuit Notebook” and “Serviceman’s Log”. New board & software from BrisbaneSilicon Thanks for publishing the review of our ELM11 FPGA board in Silicon Chip (May 2026; siliconchip.au/Article/ 20241). Your readers might be interested in some more recent BrisbaneSilicon developments. We’re working on the ELM11-Feather board, which uses the well-known Feather board layout to allow the connection of FeatherWing add-on boards from Adafruit’s Feather ecosystem (https://brisbanesilicon.com.au/elm11-feather). We’ve also introduced the Arvore IDE, which provides a project manager, code editor and runtime environment for uploading to ELM11 boards, as well as a mode for selecting and installing a Hardware Overlay (https://brisbanesilicon. com.au/arvore-ide). Craig Haywood, Founder, BrisbaneSilicon. EVs still have their limitations Regarding the article on EV Charging in the October 2026 issue (siliconchip.au/Article/20842), I think it is important that readers realise that long-distance EV driving in Australia is convenient only if (1) you are prepared to stop fairly frequently, (2) those stops are at specific locations that have a suitable charger, (3) those stops are of sufficient duration for the car to charge, and (4) the whole trip is pre-planned. We’ve now done over 60,000km in our EV, but because of these ‘long-trip’ limitations, now never take it further than a 300km round-trip from home. We recently bought a diesel car specifically for long trips, as my wife would say of the EV when a long trip was planned, “We’re not taking that silly car!” The diesel has a 1100km range, can be refuelled in five minutes anywhere in Australia, and requires no trip pre-planning whatsoever. In the diesel, we can stop at a country bakery for lunch (not at a petrol station EV charger); we change our minds halfway through a trip and decide to go a different way, even if that adds 300km; and it doesn’t matter if suddenly it rains or there is a headwind (both can be real worries in an EV when stretching range). To be honest, after buying the diesel, we feel delightfully free again! EVs have pluses and minuses, but long trips are definitely a minus – no matter what EV proponents might say. Julian Edgar, Dalton, NSW. Other PDP-11 computer clones existed The Russians were not the only ones to make copies of the Digital Equipment Corporation (DEC) PDP-11 (Serviceman’s Log, Silicon Chip September 2026; siliconchip.au/ Article/20729). In the 1970s, the Computer Machinery Company Limited 4 Silicon Chip (CMC) in the UK and its North American affiliate, the Computer Machinery Corporation, were manufacturing copies of both the PDP-8 and the PDP-11, which must have been built under license to DEC. At the time, CMC was a division of the Pertec Computer Corporation. Pertec had started life as the Peripheral Equipment Corporation, a manufacturer of magnetic disk drives and tape drives. Having acquired several smaller computer companies, they rebranded their new operation as Pertec Computer Corporation. CMC specialised in minicomputers for the data entry market. These key-to-disk computers provided a more efficient means of data entry to mainframe computers than the earlier punched card method. The completed batch data on the disk was then sent to the mainframe bureau, either physically by magnetic tape or via telephone data transmission. Their product was known as the CMC 3/5 Key Processing System, for which Amalgamated Wireless Australasia (AWA) had the Australian agency. The two models were based on copies of the DEC general-­ purpose minicomputers, either the PDP-8 or the larger PDP11. The model CMC 3 was based on the DEC PDP-8 and the model CMC 5 was based on the DEC PDP-11. These computers were fitted with circuit boards of magnetic core memory. Ross Stell, Kogarah, NSW. Older PICkits are far from useless! Your readers might be interested in downloading PIC­ kitminus (https://github.com/jaka-fi/PICkitminus), which gives Microchip PICkit 2 and PICkit 3 programmers support for more modern devices. In total, it supports 1594 devices, with a few limitations. PICkitminus needs to update the bootloader on PICkit 3 to use it; software allows it to be reverted back to use MPLAB again. Do not confuse it with PICKitplus, which is a paid program with similar claims. I have been using PICkitminus with a clone PICkit3.5 and works wonderfully as a workaround when there are problems with my SNAP, such as the lack of target voltage delivery. In my opinion, the software is so fast and efficient that it’s better than using MPLAB IPE v6.20. John Slade, Hamilton, New Zealand. Overly complex microcontrollers and using varnished MDF Thank you for keeping the Silicon Chip magazine alive through these trying times. It is nice to see that the magazine has not become little more than an advertising platform, like many of the American and British magazines. It was lovely to see the DCC projects. I have been wanting Australia's electronics magazine siliconchip.com.au ATEM Television Studio Portable all-in-one live production switcher with streaming and network storage for DaVinci editing! ATEM Television Studio is a professional live production switcher built into a broadcast control panel so it can be used for high end work while being extremely portable. You get a powerful switcher with 8 standards converted SDI inputs, aux outputs, 4 chroma keyers, 2 downstream keyers, SuperSource, 2 media players and lots of transitions! There are even ISO models that record all 8 inputs for editing! Connect up to 8 Broadcast Cameras Easy to Use and Fast to Learn Built In Fairlight Audio Mixer There’s never been a switcher that’s easier to use, as you simply press any of the program row buttons on the front panel to cut between video sources. You can select from exciting transitions such as dissolve, or more dramatic effects such as dip to color, DVE squeeze and DVE push. You can even add a DVE for picture in picture effects with customized graphics. Then you can live stream the results! With a built in Fairlight audio mixer, ATEM Television Studio makes it possible to do complex live sound mixing. The internal mixer features enough channels for all SDI inputs, as well as extra channels for the XLR, RCA and MADI inputs! 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ATEM Television Studio HD8 ...................$4,209 ATEM Television Studio HD8 ISO........ $4,675 ATEM Television Studio 4K8.....................$7,765 Learn more at www.blackmagicdesign.com/au Learn More! DCC decoders for some time, despite having to put the model trains to one side for a while. Of course, the appearance of the DCC Base Station, the DCC Remote Controller, and the DCC Booster projects increased my interest. After reading the projects, I decided I will probably buy several DCC Decoder kits eventually, but I am unsure about the other units. Silicon Chip has used the PIC16F18146 a few times, and I have ignored it, but with the DCC projects, I wanted to know more about it and downloaded the datasheet. The datasheet is at least double the size of any other PIC16-­ series datasheet that I have. It is almost unusable because of its size, and that’s something, because Microchip, in my opinion, has (or perhaps had) some of the best documentation that I have ever seen. This is a ‘do everything’ chip which, for me, makes it unusable. I like to work at the silicon level with the registers, pins, and ports almost at the raw instruction level. With a chip like this, I would be wasting a lot of time and effort sorting out what is needed from what is not needed to perform a function. It could be argued that I should use high-level software to configure the chip, but then the chip becomes a black box and there’s no pleasure in that. Besides, why would I want to add another source of bugs to a project? I will stick with the older PIC microcontrollers. I have substantial quantities to satisfy my future needs. On another subject, a little while ago, I wondered if it would be feasible to use varnished MDF sheet as a support for circuits, just like fibreglass sheet. Varnished timber had been used early in the last century, so varnished MDF should work. I bought a 900 × 600mm sheet of 3mm MDF ($6.08) and a 900 × 600mm sheet of 6mm ($9.58) from Bunnings, cut two 300 × 450mm pieces from each sheet, then varnished them with Bondall clear varnish ($11.77 for 250mL). From one of the 6mm sheets, I cut three samples and tested them for resistance using a 1000V DC supply. At the smallest separation of 5mm between the test points, the lowest resistance was 18.1MW and the highest was 52.9MW. Considering that I very rarely use voltages above 50V, I believe varnished MDF would be suitable for many experiments where high impedances are not involved. Applying varnish diluted with mineral turpentine followed by two normal coats has worked, but I failed to ensure the MDF was completely dry first; it should ideally be dried first. One noticeable effect of this method was that the MDF became more rigid and does not flex easily. One of my projects, which I still haven’t finished, is to enclose some USB flash drives in a fireproof enclosure with (hopefully) a two-hour rating in case my house is destroyed by fire. I need a strong steel box, but they are expensive. While at Bunnings, I noticed Syneco cash boxes. One of these, 200mm wide, 160mm deep and 90mm high, fully painted, hinges into two equal halves, and with a lock, costs just $11.95. It may not be suitable for the fireproof enclosure, but it certainly should be considered for various projects. The product code is 9 321396 044944. George Ramsay, Holland Park, Qld. Back Issues The UK ’s Circui t Pr Electractical onics fT sTa r TE r premier electron ics so and Underst Surgery using anding and gyrato rs Make computin g ma ker ma Mrom Finishin h Mic E Th g gazine light con the PicoMite ite E ‘sP La troller T’ aT Audio softwar smart e Designi Out sw iTc h- on discreteng a practic ! al audio op am a Mi p GPS-Sy Analog nchronise ue Cloc d k it wit Ta 6- d Ec WIN M mTo ICRO A CH u Dev ch AR IP elo 10 adE pm 00 LLionPico r Es Kit ent PrEc MisE VaLU ite smis Ta n c Es Tolight E b ox finECont art YoUr TUnErolle dEsiG r ns WIN! Microch ip Inte grat Graphic ed sE s and Touch M CuriTE osity sT – Pa luation bUEva iLd Kit an rT 3 d Us siL ic E oU on ch r ULTiM Ec kE aT E r Jump start Mini LE Driver D Egg Tim er – eg to pe gcellen rfectio t brea n! kf ast, tim Compl PLUS! APRIL 13 Cover.in dd 1 ractica lelec practic ed etin g WideTechno range the Tal inter Cool Bea k – My tru face, Ohmmet th, you ne r truth techn Net Wo ns – Arduin er and AI o tal t work, cir o Boo rk – Rou k, pic ters, pow tcamp: new n’ mix cuit Surg www.e bo er sup Sep 202 ery, re lectron plies, TEM ards update 3 £5.9 adout, publish 9 ! U and ing.co 09 more m 9 7726 <at>p 32 5730 30 alelec APRIL 201 3 £4.40 tronics Practical Electronics is the UK’s premier electronics, computing & maker magazine. Each month has a wide variety of electronics projects suiting beginners and experts alike. It also includes many different features on topics like audio, radio, computers and more. 14/02/2 013 10:33:4 7 24 YEAR COLLECTION OF PRACTICAL ELECTRONICS Every issue of Practical Electronics published from January 2000 to December 2023. Covering 288 magazines & over 20,000 pages of content; see siliconchip.com.au/Shop/3 PDF Download SC7650 ▸ $165 The articles can be downloaded per month, year or the entire block. Some of the excellent columns of Practical Electronics include Audio Out, Circuit Surgery, Techno Talk and more. The download size is approximately 5.4GB. 6 Silicon Chip PDFs on USB SC7645 ▸ $180 plus postage cost Supplied on a 32GB Silicon Chip branded USB flash drive. Purchasing this also gives you access to the download version shown opposite. Australia's electronics magazine siliconchip.com.au Comments: while we understand the appeal of simpler microcontrollers, having many peripherals does not necessarily make a device more difficult to use. There is no need to understand or configure peripherals that aren’t required for an application; they can simply be ignored. With the PIC16F18146, unused peripherals can also be disabled with a few register writes to reduce power consumption. The datasheet may look daunting because it documents everything the device can do, but there is no need to read it from cover to cover. In practice, you can read the introductory sections, then use the contents to jump straight to the sections covering the peripherals you actually need. So for a simple application, it is quite practical to use little more than the processor core and GPIO pins, perhaps with the ADC or a timer as required, and ignore most of the unused peripherals. Given how inexpensive these modern, highly capable microcontrollers are, we don’t see much disadvantage in having additional functionality available even when most of it goes unused. Regarding using varnished MDF as a substitute for fibreglass, it seems reasonable for some low-voltage circuits that don’t rely on high impedances, but we would not use it for high-voltage or mains applications. That’s because of the possibility it could absorb moisture over time and become significantly more conductive, especially if the varnishing job is not perfect. LEDs vs incandescent lamps The experience Bruce Pierson related in the September issue regarding incandescent, CFL and LED lamps (“LED globes are not as reliable as promised”) is most remarkable. Incandescent lamps rarely last as long as 10 years in normal domestic use. Some in rarely used rooms might, but only if the lamps were used as infrequently as the rooms. Instead of suspecting the lamps, I suggest that he get an electrician to check the wiring of his house. I notice that Dundathu is a suburb of Maryborough and should have a reliable electricity supply, but it would be useful to check if his neighbours have similar problems. Another culprit might be a nearby radio transmitter. Incandescent lamps are relatively insensitive to spikes on the wires, but really big spikes might overwhelm the protection circuits in CFL and LED lamps. Most of my lamps are now LEDs, with a few CFLs lurking about. I have replaced a few since installing them, but I do this so rarely that needing to replace one is a big surprise. Keith Anderson, Kingston, Tas. More on LED globes I refer to the letter in the September issue with regard to LED globes (p10). My shed has several 12V LED floodlights, some 20W, some 10W. Both types have suffered failures after only a few years and the total run-times are not great. I assumed that the problem was overheating. I did an experiment to see if it was viable to feed the lights with pulsed DC with different duty cycles. Unfortunately, this proved fruitless as the temperature of the heatsink was higher with lower pulse widths, such as an 80% duty cycle. My guess is that the power supplies within these lights use current-control rather than voltage. Joe Edgecombe, Toodyay, WA. Comment: you are likely right since LED floodlights typSC ically include constant-current drivers. 8 Silicon Chip Australia's electronics magazine siliconchip.com.au Blackmagic Pocket Cinema Camera 4K Advanced digital film camera in a compact design with 4/3 sensor and Blackmagic RAW! Dual Native for Exceptional Low Light Performance Dramatically improve the production value of your work by upgrading to digital film! Blackmagic Pocket Cinema Camera is better than a simple video camera because it has professional features allowing you to create the same “look” as Hollywood feature films. The combination of high dynamic range, great low light performance and Blackmagic RAW gives you feature film images with precise skin tones and gorgeous organic colors. The Blackmagic Pocket Cinema Camera features dual native ISO up to 25,600, which means it is optimized to minimize grain or noise in images, while maintaining the full dynamic range of the sensor. 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Its closest competitor, Advanced Micro Devices (AMD) also has a long and storied history that deserves to be told. I ntel was established on the 18th of July, 1968, while AMD (Advanced Micro Devices) was incorporated less than a year later, on the 1st of May, 1969. Like Intel, AMD’s fortunes have been made mainly on the back of computer CPUs. AMD’s market capitalisation (the total value of all outstanding shares in the company) surpassed Intel’s in February 2022. Today, AMD’s market cap is ~US$1 trillion while Intel’s is ~US$600 billion at the time of writing. The Fairchild Semiconductor connection Intel and AMD have some history in common, as they were both founded by former employees of Fairchild Semiconductor, and are thus known as “Fairchildren”. In 1955, William Shockley, winner of the 1956 Nobel Prize in Physics for 12 Silicon Chip co-inventing the transistor, founded Shockley Semiconductor Laboratory in Mountain View, California (primary operations began in 1956). Shockley was a brilliant scientist but a poor manager. In 1957, eight of his key employees, who came to be known as the “Traitorous Eight”, left to found Fairchild Semiconductor. Fairchild Semiconductor was not founded as a totally independent company like it might be today because the concept of venture capital funding didn’t really exist back then. Thirty companies were approached to assist in the founding of this new venture. It was Sherman Fairchild of Fairchild Camera and Instrument who provided US$1.38 million in funding (a very large sum at the time) plus a US$3 million buyout option. In exchange, the new semiconductor operation was Australia's electronics magazine established as a division of Fairchild Camera and Instrument, named Fairchild Semiconductor. This arrangement gave the eight engineers the capital and resources they needed, while giving Sherman Fairchild control and the potential for making a huge profit in the fast-­ growing semiconductor business. Fairchild Semiconductor became one of the most fertile companies in history, in the sense that many of its engineers and executives left to start other important firms. Such companies include: • National Semiconductor (1959) • Amelco (1961) • Applied Materials (1967) • Intel (1968) • AMD (1969) • LSI Logic (1981) • Altera (1983) • SanDisk (1988) The venture capital firms Kleiner Perkins (1972) and Sequoia Capital (1972) also emerged from Fairchild. Jen-Hsun “Jensen” Huang worked at both AMD and LSI Logic, both “Fairchildren”, and became co-founder of Nvidia, another huge technology company that we will discuss in a future article. Disillusionment Robert Noyce and Gordon Moore were weary of what Fairchild Semiconductor had become, so in 1968, they left to found Intel. A year later, Jerry Sanders, the worldwide sales manager at Fairchild Semiconductor, also became concerned about the dire situation there and left to found AMD. The disillusionment came from the mismatch between the fast-paced, rapidly developing semiconductor industry and the old, slow-moving, conservative Fairchild Camera and Instrument parent company on the opposite coast of the USA. The parent company also took much of the profit from the subsidiary, which starved the semiconductor division of funds to reinvest. Executives were also given poor stock options and reimbursement compared to other Fairchild divisions. Finally, the East Coast management rarely visited the West Coast company, and was out of touch and bureaucratic in contrast to the entrepreneurial, hands-on approach of the semiconductor division. siliconchip.com.au The dissatisfaction grew noticeably through 1966-67 and reached a breaking point from late 1967 to 1968, leading to Noyce and Moore leaving, with Sanders following less than a year later. Unlike Noyce and Moore, Jerry Sanders was not a member of the Traitorous Eight that founded Fairchild Semiconductor. He had joined Fairchild as a sales and marketing executive, where he quickly rose through the company. However, due to management conflicts, he was pushed out of day-to-day operations and eventually took a severance package of one year’s salary. He was known for his charismatic but controversial style as director of marketing, his flashy style, his pink Cadillac and his aggressive sales approach. Jerry Sanders founds AMD After being pushed out of Fairchild in late 1968, Jerry Sanders joined a group of seven other ex-Fairchild employees who wanted to start their own semiconductor company. On the 1st of May, 1969, the eight of them officially incorporated Advanced Micro Devices (AMD), with Sanders as president (he insisted on the role, which caused some initial tension). The company initially operated from temporary premises in Santa Clara, California, moving to Sunnyvale later that year. The original eight co-founders were (as shown in the lead photo & below): 1. W. Jerry Sanders III, from sales & marketing at Fairchild, became President & CEO of AMD 2. Jack F. Gifford became director of marketing and business development at AMD 3. Sven E. Simonsen became director of engineering, complex digital operations at AMD 4. D. John Carey became managing director of complex digital operations at AMD 5. James N. Giles became director of engineering, analog operations at AMD 6. Edwin J. Turney became director of sales and administration at AMD 7. R. Lawrence “Larry” Stenger became managing director, analog operations at AMD 8. Frank T. Botte became director of development, analog operations at AMD As you can see, they came from sales, marketing, engineering and operations backgrounds at Fairchild. AMD started with almost no capital. Sanders personally raised roughly US$1.5 million through a combination of private investors, small venture capital groups, personal loans and friends. Unlike the Traitorous Eight (who had corporate backing from Fairchild Camera and Instrument), AMD was a true “bootstrap” startup. The company’s original business plan was simple and pragmatic: they wanted to become a “second source” supplier of digital integrated circuits. They would legally copy (or license) popular logic and memory chips from competitors like Texas Instruments, Motorola and National Semiconductor, then sell them at competitive prices with better customer service. AMD’s first product (the Am9300 shift register) shipped in 1970, and the company made its first profit in 1971. The strategy to become a second-­ source supplier was very wise because at the time, big buyers of chips like the US Military, General Electric (GE), Honeywell and International Business Machines (IBM) were reluctant to purchase chips unless there were multiple sources for them. The reasons for this included that there might be quality, supply or cost problems if they relied on just one supplier. Imagine investing millions in developing a new product and the sole supplier of critical components files for bankruptcy! Identifying this market niche and becoming a high-­ quality, reliable second-source supplier for such buyers was an excellent move to help gain market share. “Borrowing from friends” AMD started with almost nothing. The company was incorporated with From left-toright, the eight co-founders of AMD: W. Jerry Sanders III, Jack F Gifford, Sven E. Simonsen, D. John Carey, James N. Giles, Edwin J. Turney, R. Lawrence Stenger and Frank T. Botte. siliconchip.com.au Australia's electronics magazine November 2026  13 roughly US$100,000 of combined personal savings and small contributions from the founders. Sanders then personally led an intensive fundraising effort to raise the US$1.5-1.75 million needed to actually launch operations. This was a very small amount for a semiconductor startup, even by 1969 standards. He borrowed heavily from friends, personal contacts and a handful of small investors. One important contribution came when Jonathan Lovelace (the founder of Capital Group) personally advanced US$30,000 just to cover minimum rent and basic equipment to keep the fledgling company going. Sanders used his salesman’s bravado to close the deal, repeatedly assuring the nervous co-founders that “we’re going to get the money” even when things looked uncertain. The funding phase was finally completed in mid-1969 after months of sleepless nights and near-misses. First headquarters – humble beginnings The first “headquarters” of AMD was in the living room of co-founder John Carey’s house. They then rented two small back rooms (about 84m2 total) inside a rug-cutting company at 1040 DeGiulio Avenue, Santa Clara. It was a shared industrial space with no proper amenities; just enough room for eight desks and basic drafting tables. The founders joked that it lacked even a garage door or convenient parking. Once most of the funding was completed by September 1969, AMD moved into its first permanent facility at 901 Thompson Place, Sunnyvale. This was a 1394m2 building they purchased for US$500,000. This space housed the entire company, including the first small wafer fab, which was set up for an eight-mask, two-inch (51mm) wafer process having a 7μm feature size. It originated from Sanders’ unsatisfactory experiences at Fairchild. He had watched the parent company (Fairchild Camera and Instrument) repeatedly mistreat its best engineers and salespeople by under-paying them, giving them poor stock options, and taking profits from the semiconEquipment & early operations ductor division to fund the failing East They improvised everything with Coast businesses. the absolute minimum of equipment, Sanders believed this “profits first” buying or leasing the cheapest basic corporate mindset destroyed morale semiconductor processing equipment and drove away talent. When he they could find, such as wafer process- founded AMD, he deliberately chose ing tools, assembly equipment, etc. the opposite approach. Starting as They also used a lot of second-hand early as 1969-1970, Sanders repeator reconditioned equipment wherever edly stated his new motto in numerpossible. ous early interviews, speeches and As mentioned above, they started internal meetings. with a rudimentary two-inch wafer What he meant by this was to hire line; nothing was state-of-the-art. the best people, treat them with respect They focused on second-sourcing, and generosity (such as better stock legally copying existing logic and options, bonuses and culture) and crememory chips from competitors like ate an environment where employees TI and National Semiconductor, so felt valued and motivated. He thought they didn’t need to perform expen- that if he did that, great products and sive research and development (R&D) strong profits would naturally result. right away. The saying became AMD’s unofficial Its first product, the Am9300, was motto for decades and was printed on released in 1970. It was a second-­ corporate materials, repeated in meetsource version of a product originally ings and used for recruiting. Sanders designed by Fairchild Semiconductor. credited it as one of the main reasons The whole operation was extremely AMD was able to attract top talent lean. The founders even did much away from much larger companies of the early work themselves, while during the 1970s and 1980s. Sanders was out raising money and AMD’s main historical eras “selling the vision”. AMD has had five main historiSanders’ motto cal eras. These will be used as main Jerry Sanders’ motto was “People headings in this article. The eras are first, products and profits will follow!” roughly as follows: It became his lifelong management • Second-sourcing, cloning, philosophy and one of AMD’s core reverse-engineering and some indecultural tenets from the beginning. pendent designs (1969-1995) Fig.1: AMD’s previous headquarters in Sunnyvale, California (since demolished in 2019). Source: https://w.wiki/RGex 14 Silicon Chip Fig.2: AMD’s Santa Clara, California, headquarters in 2020. Source: https://w.wiki/RGew Australia's electronics magazine siliconchip.com.au • Independent architecture and the GHz race (1996-2003) • Innovation leadership (2003-2007) • Dark years and the Bulldozer architecture (2008-2016) • The Zen renaissance and the modern era (2017-present) Second-source, cloning, reverse-­ engineering and some independent designs (1969-1995) Second sourcing was the foundation of AMD’s business model and the key reason the company survived its difficult startup phase. In the semiconductor industry of the late 1960s and 1970s, a second-source company legally produced and sold an exact or near-exact copy of another manufacturer’s integrated circuit. Customers wanted second sources because they reduced supply risk, created price competition and guaranteed chip availability. Being a “second sourcer” as a fundamental part of AMD’s strategy in the early years was very pragmatic. They deliberately chose not to compete head-on with giant companies by inventing new chips, which would have been very difficult for them at the time. Second-sourcing enabled them to relatively easily generate revenue to grow the company without a massive investment. Jerry Sanders’ famous by-line during this era was: “We’re not in the semiconductor business. We’re in the customer service business.” This second-sourcing phase was roughly 1970-1978, keeping AMD alive during its cash-poor early years. It helped build the manufacturing discipline and customer base that allowed the company to later develop its own innovative products. AMD chose to second-source popular logic and memory chips in particular. They reverse-engineered or licensed designs from companies like Texas Instruments, National Semiconductor, Motorola, Intel and Signetics. AMD produced functionally identical parts with the same pinout and electrical specifications. However, it tried to distinguish its products by offering better quality, better packaging, better customer service, or all three. As a result of its approach to second-sourcing products, AMD could offer customers: • High reliability (they built a strong reputation for high quality and low failure rates) • Better customer support, which came from Jerry Sanders’ background in sales, promoting an attitude of providing excellent service and response to customers • Military-grade parts; AMD focused heavily on the military and aerospace market, where customers were prepared to pay premium prices The second-source model worked because it required much less R&D than designing original chips. It allowed AMD to build manufacturing expertise and cash flow, and it created strong relationships with customers who wanted alternatives to the dominant suppliers. AMD’s earned reputation as the “high-quality second source” later helped them transition into original processor designs, starting with the Am2900 bit-slice family in the mid1970s, although that wasn’t its first clean-sheet product. A bit-slice processor is a modular, multi-chip building-block approach to designing high-performance custom microprocessors. Instead of creating a complete fixed-width CPU (such as eight bits or 16 bits), the Am2900 provided 4-bit wide ‘slices’ that engineers could combine, such as four slices for a 16-bit processor, eight for a 32-bit processor and so on. Each slice contained its own arithmetic logic unit (ALU, such as the Am2901 chip), registers and shifting logic, while accessory chips like the Am2909 handled sequencing and control. This architecture was highly flexible and microprogrammable, allowing designers to create custom instruction sets and optimised processors for specific applications such as minicomputers, graphics systems, military equipment and disk controllers. The Am2900 family became popular because it offered excellent performance and scalability at a time when standard off-the-shelf microprocessors were still relatively slow and limited. First second-source products The first second-source product, released in 1970, was the Am9300, a 4-bit shift register. After that, they quickly expanded into TTL logic families (7400 series equivalents), memory chips and linear (analog) chips – see Table 1. Another important second-source milestone was AMD’s first memory chip, the Am3101 64-bit bipolar RAM chip, released in 1971 (see Fig.3 overleaf). It was based on Intel’s first product, the 3101, released in 1969. It was not licensed from Intel but reverse-­ engineered. Table 1: AMD’s second-source products, 1969-1975 Year(s) Product Description Original source Significance 1970 Am9300 Parallel load 4-bit shift register, 5V TTL Fairchild 9300 AMD’s first second-source commercial product. 1971 Am3101 64-bit bipolar RAM Reverse-engineered from the Intel 3101 AMD’s first second-source RAM chip. 1971 Am7400 series TTL logic family (NAND Texas Instruments 7400 gates, inverters, flip-flops etc) series One of AMD’s biggest revenue drivers, especially military-grade versions. 1972-3 Am1488 Am1489 RS-232 line drivers & receivers National Semiconductor and Motorola Very successful in communications and computer peripherals. 1973 Am1702 2kib EPROM Intel 1702 One of the first memory products AMD second-sourced. 1975 Am9080 8-bit microprocessor Intel 8080 AMD’s first microprocessor (reverseengineered). It had faster variants than the Intel product. siliconchip.com.au Australia's electronics magazine November 2026  15 Fig.3: the die and wire bonding of AMD’s first RAM chip, the 64-bit Am3101, reverse-engineered from Intel’s 3101. Source: www.facebook. com/share/p/1ELjPTFSj7/ Fig.4: AMD’s first proprietary chip, the Am2501. Source: https:// overclockers.ru/blog/gummibear/ show/45878/pervaya-sereznayapobeda-sobstvennoj-arhitekturyamd-burevestnik-thunderbird Fig.5: the AM2501 in its package with the encapsulation material removed to reveal the die, bond wires and part of the lead frame. Source: Ken Shirriff (https://x.com/i/ status/1218982024070955009) Fig.6: a die photo of the Am2501 chip. Source: https://prohoster.info/ en/blog/novosti-interneta/amd-bylaosnovana-rovno-50-let-nazad-sostartovym-kapitalom-v-50-tysyach 16 Silicon Chip Intel did not sue because, at the time, patent and copyright laws did not apply to silicon layouts as long as they were not a direct copy based on the manufacturing masks (the blueprints to etch the silicon). In fact, Intel welcomed the Am3101 because, at the time, companies like Honeywell and Burroughs refused to design Intel chips into their systems unless a second-source supplier was available to guarantee supply and price competition. AMD thus also inadvertently helped Intel popularise its product. AMD soon built enough credibility and cash flow that it began moving beyond pure second-sourcing into original designs, most notably the Am2900 bit-slice processor family, introduced in 1975. Jerry Sanders often boasted during this period that while other companies competed on technology, AMD would compete on quality and service, and it worked. This second-source strategy was extremely successful and kept the young company alive during its most vulnerable years. The Am9300 The Am9300 was released in 1970. As a second-source component originally designed by Fairchild Semiconductor and designated 9300 (also second-sourced or cloned by National Semiconductor [DM9300] and Texas Instruments [SN9300]), it was a relatively simple but widely used logic device capable of parallel-load, shiftleft, shift-right and hold functions. It was a 4-bit medium-scale integration shift register containing around 85 transistors and 40 resistors, with 125 components in total and 26 logic gates. The Am9300 reflected AMD’s early strengths and market positioning. Although the company lacked the resources to design complex original chips in the beginning, its strength was in manufacturing high-quality bipolar logic devices with superior reliability and consistency. To do this, AMD applied its Fairchild-inherited process technology and rigorous quality control to produce versions that often outperformed the original source parts, particularly in military and industrial applications, where failure rates had to be extremely low. By successfully producing and selling the Am9300, AMD demonstrated Australia's electronics magazine its fundamental early capability: the ability to manufacture dependable, high-quality semiconductor parts and provide excellent customer support. The Am9300 was produced using bipolar TTL (transistor-transistor logic) process technology, which was the same high-speed bipolar process AMD inherited from its ex-Fairchild engineers. This bipolar TTL technology used gold doping for faster switching and was well-suited to the military, aerospace and industrial markets that AMD targeted. AMD’s self-designed products After AMD established its second-­ sourcing strategy, it had the confidence and cash flow to start developing its own chips, as shown in Table 2. Second-­sourcing remained AMD’s ‘bread and butter’ in the early years, and the revenue from that also allowed them to start designing its own chips. The Am2501 (1970) was AMD’s first proprietary/in-house designed logic chip, while the Am2900 family (1975) was its first in-house processor and by far its most important early innovation. We will now look at both of these chips and their significance. The Am2501 The Am2501 (Figs.4 & 5), was AMD’s first in-house designed product. It was a reflection of the company’s capabilities and strategic thinking in its earliest days. As a medium-scale integration TTL 4-bit binary up-only counter, it was a relatively straightforward but practical logic device that reflected AMD’s core strengths at the time, such as its bipolar process technology and the company’s focus on reliability and quality. Rather than attempting a highly complex chip as its first original design, AMD chose a useful, mid-­ complexity device that allowed it to prove its design and manufacturing abilities while minimising risk. Engineering schematics are not available, but it is estimated to have had around 150-250 transistors. Putting that into perspective, just one year later the world’s first microprocessor, the Intel 4004, had 2300 transistors, and today’s AMD processors have 8-30 billion transistors. The Am2501 also aligned with AMD’s early emphasis on serving military and industrial customers, markets that demanded high-reliability parts siliconchip.com.au and were willing to pay a premium for better quality and consistency. It was designed to meet rigorous US Military Standard, MIL-STD-883. Its commercial success helped validate AMD’s and Sanders’ strategy of competing on quality and customer service rather than cutting-edge complexity. It, along with the second in-house designed product, the Am2505, helped propel AMD’s annual sales to US$4.6 million by the end of 1971. The Am2900 The Am2900 family of chips represented a big leap forward for AMD, moving from designing relatively simple logic chips like counters and multipliers to creating an advanced, flexible microprocessor system that customers could use to build custom high-­performance multi-chip CPUs. The AM2900 series 4-bit bipolar bitslice microprocessor family, released in 1975, marked the transition of AMD from mostly second-sourcing to being a force in complex, original microprocessor products. The Am2900 family was generally considered better-performing than competing solutions when it was introduced in 1975. It had a higher speed, since the Am2901 (the core 4-bit ALU slice – see Fig.7) was faster than Intel’s own 3000-series bit-slice chips. AMD’s bipolar process technology gave it excellent speed for the era. Table 2: AMD’s first in-house chip designs Rank Year(s) Product(s) Type Status First 1970 Am2501 4-bit synchronous uponly binary counter First in-house designed product Second 1971 Am2505 4-bit by 2-bit two’scomplement digital multiplier Second in-house design; fastest digital multiplier on the market ... 1971-74 Various Smaller logic and memory chips More in-house designs Major milestone 1975 Am2900 family Bit-slice microprocessor architecture First major complex original architecture It also offered a very flexible, microprogrammable architecture. Designers could easily create high-performance custom CPUs of any bit width (8, 16, 32, 64 bits etc), which was very attractive for minicomputer makers, graphics systems and military applications, where cost was not such a major concern. In addition, it had superior instruction throughput; systems built with the Am2900 family often achieved significantly higher performance than systems based on the Intel 8080 or 8085. The Am2900 was an excellent choice for high-end applications, and because of its speed and flexibility, the Am2900 became very popular in highend minicomputers, disk controllers, graphics processors and military and aerospace systems. Fig.7: a die photo of the Am2901 with the metal layers included. Source: www.righto. com/2020/04/ inside-am2901amds-1970s-bitslice.html siliconchip.com.au Australia's electronics magazine Some examples of its use included the Atari arcade video games Tempest and Battlezone (which used four Am2901s for vector calculations), the Xerox Star Workstation, which featured an early GUI (graphical user interface) and a mouse, and the Chyron IV character generator used in television broadcasting, which was released in 1977. While the Intel 8080 (and AMD’s own Am9080 clone) was a good general-­purpose 8-bit microprocessor, the Am2900 was aimed at a higher performance tier. It was not a direct competitor to the 8080 because it was in a different class (bit-slice), designed for customers who needed more speed and customisation than a standard microprocessor could offer. The Am2900 family was widely regarded as one of the best-­performing bit-slice solutions available in the midto-late 1970s, giving AMD its first real reputation as a company that could deliver high-performance, original designs. The Am2900 family reflected AMD’s strengths at the time. Having built its early reputation on high-­ quality bipolar manufacturing and logic design (as demonstrated by chips like the Am2501 and Am2505), AMD expanded these capabilities to create a modular, high-performance bit-slice microprocessor architecture. With its bipolar process technology, AMD could deliver superior speed compared to competing MOS-based solutions. This leveraged AMD’s manufacturing expertise in high-speed bipolar logic and its increasing abilities in designing modular building-­ block chips. The Am2900 family thus represented AMD’s successful transition from a mostly second-source supplier to an innovative designer. November 2026  17 The Intel agreement As noted in Table 1, the Am9080 (Figs.8 & 9) was released in 1975. While based on the Intel 8080, it was an unauthorised, unlicensed reverse-engineered product. As was common in the industry at the time, AMD decapped an Intel processor, photographed the die layers and analysed its circuitry. AMD’s engineers then created their own masks and layout to manufacture a chip that was functionally identical and pin-compatible with the Intel 8080. It used the same instruction set and behaved the same way electrically. Both the AMD and Intel devices had 4500-6000 transistors (depending on how they are counted). The performance of the Am9080 was equivalent to the Intel 8080, but many customers preferred the Am9080 over the Intel 8080 specifically because of AMD’s better quality control and customer support. Jerry Sanders often highlighted the point that AMD didn’t try to beat Intel on speed with the Am9080; they beat them on quality and service. It should be noted, however, that AMD’s proprietary N-channel MOS manufacturing process allowed them to produce faster variants than Intel, with a maximum clock speed of 4MHz compared to Intel’s maximum speed of 3.125MHz. In 1976, they reached a formal second-­ source licensing agreement with Intel that legalised its production of the 8080 family, including support chips. This cleared any possible past intellectual property infringement issues (but others were to come later). This 1976 agreement was a major milestone for the company, as it gave them credibility and access to important markets, especially military & industrial, that often required approved second sources. AMD paid Intel an initial fee of US$25,000 plus US$75,000 per year in royalties for the license. The Am2900 and Am9080 You may have noticed that both the Am2900 and Am9080 were released to market at the same time, in 1975, the Am2900 being AMD’s own design and the Am9080 based on Intel’s 8080. This marked AMD’s ‘dual entry’ into the microprocessor market. There was no functional overlap, as the two products served different purposes. The Am9080 was suitable for mass-market microcomputing and early PCs (like some S100 bus systems), industrial controllers and hobbyists, where its low cost and monolithic design were prioritised over speed. The Am2900 was for high-end enterprise systems, like the minicomputer and mainframe markets supplied by Digital Equipment Corporation (DEC) and Data General. They required customised word lengths and high speeds for scientific applications and graphics terminals, with little regard to cost or the complexity of building a modular processor from multiple chips. To give an idea of prices, the Am9080 cost about US$0.50 per chip to manufacture and sold for US$1020, undercutting Intel, although the military versions sold for US$700. It should be noted that AMD did not focus on the low-cost end of the Am9080 market because they could sell them to the military for US$700, while still only spending US$0.50 per unit on manufacturing. The Am2900 cost hundreds of dollars for a full family of chips, including around US$15-30 for individual Am2901 ALUs, making it cost-­ prohibitive for ordinary consumers. Second-source success to innovation (1978–1985) The combination of the successful Intel 8080 licensing agreement in 1976 and the strong market reception of the Am2900 bit-slice processor family gave AMD its first taste of prosperity. By the late 1970s, the company had grown rapidly, built a solid reputation for quality, and established itself as a major player in the military, industrial and early personal computer markets. However, this success also created a strategic dilemma. As the personal computer revolution accelerated in the early 1980s, it became clear that the future of the microprocessor industry would be dominated by general-­ purpose CPUs rather than modular bit-slice designs. AMD’s significant dependence on second-sourcing and logic chips left it vulnerable. The 1982 Intel agreement In 1982, AMD signed a 10-year technology exchange agreement with Intel that was heavily driven by IBM, who wanted a reliable second-source supplier before it would commit to using the Intel 8086 and 8088 in the IBM PC (first released August 1981). Under this agreement, Intel gave AMD complete blueprints and microcode to officially manufacture exact clones of these products. This arrangement further enhanced AMD’s recognition as a major silicon manufacturer. Fig.8: a die photo of the AMD Am9080A microprocessor (AM9080ADIB). The layout was AMD’s own, as they reverse-engineered the Intel 8080. Source: https://w.wiki/RGet Fig.9: the Am9080 reverse-engineered clone of the Intel 8080. Source: https://w.wiki/RGf2 18 Silicon Chip Australia's electronics magazine siliconchip.com.au Fig.10: the AMD 8086 clone came in a standard dual-inline package that was compatible with Intel’s. Source: https://w. wiki/Q8N There is an obvious timing discrepancy. IBM released the PC before Intel had a second-source supplier. IBM started production of the PC on the basis that Intel had promised to find a second-source supplier, and the preliminary deal with AMD was agreed to in October 1981, with a formal contract signed in February 1982. The agreement provided for Intel to provide the layouts for the 8086 (Fig.10), 8088, 80186 and 80286 processors. AMD ‘paid’ Intel by developing peripheral chips or other technology of equivalent complexity. Expiry of the 1976 agreement postponed The 1982 agreement mentioned above did not replace the former 1976 agreement, but added to it. While the original 1976 cross-­ l icensing agreement with Intel for the 8080/ Am9080 was to expire in 1985, the new agreement effectively extended the technology-­ sharing arrangement to December 1995. The 1982 agreement was effectively a barter system, with no payments or royalties involved; exchanges were based on technical complexity, according to a formula such as a point value assigned to each die based on die size, transistor count and engineering hours. To ‘earn’ the blueprints for a new Intel CPU, AMD had to trade back alternative chips like memory controllers, networking chips, mathematics coprocessors etc that equalled the same number of complexity points as Intel was trading. Intel backs out these designs, claiming they were “substandard” and not of sufficient value to trade for the 80386. They thus claimed AMD had no right to manufacture the chip. Intel did not cancel the contract; they just dragged things out. Eventually, AMD realised Intel was never going to give them the blueprints for the 80386 and filed for legal arbitration in April 1987. The case dragged on for nearly five years. During those years, Intel had a 100% monopoly on the 80386 market. This refusal forced AMD into a difficult situation. The company could no longer rely on easy access to Intel’s latest designs and now faced a stark choice. It had to either remain a successful but secondary supplier of older-­generation parts, or take the enormous risk of developing its own competitive x86 processors. AMD’s leadership, still led by the flamboyant Jerry Sanders, chose the more ambitious but high-risk path. The company began investing heavily in original CPU design talent and advanced manufacturing processes. This period marked the beginning of AMD’s painful but necessary evolution from a clever second-source company into a true innovator. The experience gained during the Am2900 years, particularly in complex logic design, bipolar process technology and high-reliability manufacturing provided a strong technical foundation. However, moving into direct competition with Intel on general-purpose microprocessors would require entirely new skills, massive investment and a willingness to challenge Intel both technically and legally. By the mid-1980s, AMD had outgrown its original business model (second-­sourcing). The stage was now set for one of the most dramatic events in semiconductor history. That is, AMD’s attempt to break Intel’s monopoly on the 32-bit 80386 and 80486 architectures. Breaking Intel’s monopoly By the mid-1980s, Intel had successfully turned the x86 architecture into a near-monopoly. With its refusal to grant AMD a license to produce the 80386 microprocessor, AMD faced a critical threat. Undeterred, AMD embarked on one of the most ambitious and legally risky projects in its history. It decided to reverse-engineer the Intel 80386. The company assembled two separate teams. One team, which had never seen Intel’s 386 documentation or microcode, analysed the physical chip through decapping, microscopic photography and electrical testing to create detailed functional specifications. A second, completely isolated team designed a new chip layout based solely on those specifications. This ‘cleanroom’ technique was designed to avoid any direct copying of Intel’s copyrighted layout material, while achieving fully functional compatibility. They did, however, copy the microcode, the software that controls the chip. There are some variations of exactly what happened, but we believe this is the correct version. Fig.11: an Am386 processor in a TQFP package. It was the first non-Intel manufactured 80386 processor. Source: https://w.wiki/RGev When Intel introduced the innovative 32-bit 80386 in 1985, it realised it was going to be hugely popular and a cash cow. They did not want to share this with AMD. Intel’s plan was to keep AMD away from the 80386 or subsequent processors. AMD offered Intel dozens of its original peripheral chip designs to pay for the 80386, but Intel rejected siliconchip.com.au Australia's electronics magazine November 2026  19 In 1991, AMD released the Am386, the first non-Intel 80386 processor (Fig.11). The chip was pin-­compatible with Intel’s design and available in both 25MHz and 40MHz versions. Technically, the Am386 was a great success. It delivered performance comparable to, and in some cases, slightly better than Intel’s own 80386 (released in 1985) due to minor architectural optimisations and AMD’s manufacturing strengths. More importantly, it was significantly cheaper and, for the first time, offered customers a real alternative in the 32-bit x86 market. Intel immediately sued AMD for copyright infringement, focusing primarily on the microcode. The resulting legal battle became one of the most important cases in Silicon Valley history. In 1992, a US federal jury ruled in AMD’s favour on the important microcode copyright claim, determining that AMD had not illegally copied Intel’s code and that they were allowed to do it under the 1976 cross-licensing agreement and the 1982 second-­sourcing contract. The case eventually reached the US Supreme Court, which declined to hear Intel’s appeal, effectively upholding AMD’s victory. This was an extremely important legal win, as it established that functional compatibility through clean-room reverse engineering was legally defensible. It fundamentally weakened Intel’s ability to maintain control over the x86 architecture through copyright claims. The curious copyright symbol One of the most curious details of the Am386 story was that AMD Am386 processors physically carried an Intel copyright symbol (“© Intel 85”) etched onto the silicon die – see Fig.12. Fig.13: an AMD 80486DX2 die. The apparently solid or hatched rectangular are likely cache memories. Source: https://w.wiki/ RGez Fig.14: an early Am486 chip (40MHz version) in a PGA (pin grid array) package; a package style AMD stuck with until the early 2020s. Source: https://w.wiki/RGey AMD incorporated the Intel copyright symbol to acknowledge that it had used Intel’s microcode (or at least that the chip was based on elements of the 80386; once again, there are different versions of the precise details). All Am386s shipped with this notice. Reverse-engineering the 80486 After the success and legal victory surrounding the Am386, AMD moved aggressively into the 80486 market. However, this proved far more difficult. The 80486 contained significantly more complex microcode and integrated features (such as an on-chip floating-point unit in later versions). AMD’s first 486-compatible processors, the Am486 series, launched in 1993 (see Figs.13 & 14). They were considered respectable but generally lagged somewhat behind Intel’s products in performance. However, they gave customers a choice and kept downward pressure on Intel’s pricing. AMD made a major agreement with Compaq to supply the Am486 for the Fig.12: the “© Intel 85” notice in the silicon of an Am386 processor die. Source: https://w. wiki/RGeu budget Presario home PCs, which enabled them to undercut the price of other computers using the Intel 80486. The ‘386/486 wars’, as the CPU competition between AMD and Intel became known, fundamentally changed AMD’s path. The company transformed from a respected secondary supplier into a legitimate challenger to Intel’s dominance. More importantly, these ‘wars’ forced AMD to invest heavily in engineering talent and manufacturing capabilities. The legal and technical experience gained during this period would prove essential years later when AMD developed its own in-house designed K5, K6, K7 and eventually the groundbreaking Zen architecture, which we will cover in a later part of this series. In summary, by the mid-1990s, AMD had proven it could compete at the highest level of the microprocessor industry, not just by copying Intel, but by outmanoeuvring and out-­ competing them both legally and in the marketplace. Thus, the days of being a pure second-source company were over. AMD’s next move was to design its own processors and make the strategic decision to cease being a second-­ source supplier. Next month In part two of this series next month, we will pick up where we left off, in the mid-1990s, after the launch of the AM486. This was the start of a new era for AMD – no longer merely content to clone or license Intel processors, they started designing their own chips to SC compete directly with Intel’s. 20 Silicon Chip Australia's electronics magazine siliconchip.com.au Table 3: AMD’s main processor families Second-source, cloning and reverse engineering era (1969-1995) 1975 Am9080 and Am2900 The Am9080 was a reverse-engineered clone of the Intel 8080, while the Am2900 was an in-house designed bit-slice processor family. 1982 Am8086 A licensed version of Intel’s 8086 processor. 1984 Am286 A licensed version of Intel’s 80286 processor with higher clock speeds. 1988 Am29000 The first of a family of 32-bit RISC processors used in embedded applications like laser printers, parts of which were incorporated into the later K5 processor. 1991 Am386 A reverse-engineered 80386 clone that triggered a legal battle with Intel over microcode copyright. It was popular due to its 40MHz speed, beating Intel’s 33MHz. 1993 Am486 A high-performance reverse-engineered 80486 clone that culminated in a longterm deal with Compaq. Independent architecture and the GHz race (1996-2003) 1996 AMD K5 AMD’s first independently designed x86 processor. It was a little slower than Intel’s Pentium overall. It was based on elements of an unreleased version of the Am29000. 1997 AMD K6 The K6 integrated multimedia instructions (MMX) and drastically drove down the cost of desktop personal computers. 1999 AMD K7 Athlon The debut of the Athlon brand with a drastically superior architecture. It became the fastest x86 processor on the consumer market, significantly outperforming the Pentium III at the same clock speed. 2000 Athlon 1000 AMD broke the 1GHz barrier before Intel. Innovation leadership (2003-2007) 2003 Athlon 64 and Opteron (K8) AMD introduced the x86-64 64-bit system that’s still in use today. It entered the server market with the Opteron, while the Athlon 64 dominated gaming PCs with an on-die memory controller. 2005-9 Athlon 64 X2 The first native dual-core x86 processor. 2007 Phenom and Phenom II (K10) Native quad-core architectures. AMD also released K10 Opteron budgetfriendly server processors. Dark Years and the Bulldozer architecture (2008-2016) 2011 Bulldozer and FX Series The FX series used ‘modules’, sharing resources between integer cores. It suffered from poor single-threaded efficiency as a result and had high power consumption. 2011 The first APUs (accelerated processing units) AMD introduced the APU under the Fusion project, merging a CPU and a powerful Radeon graphics die for budget computing. The Zen Renaissance and the Modern Era (2017-Present) 2017 Zen 1 (Ryzen 1000 series) Zen 1 introduced simultaneous multi-threading (SMT) to AMD processors and brought 8-core/16-thread power to consumers on a 14nm process. 2018 Zen+ (Ryzen 2000 series) A process shrink (12nm) that improved clock speeds, latency and power efficiency. 2019 Zen 2 (Ryzen 3000 series) The first consumer CPU using a multi-die chiplet design, vastly lowering manufacturing costs and exploding core counts on 7nm. 2020 Zen 3 (Ryzen 5000 series) Unified 8-core complex (CCX) that eliminated internal latency. Introduced 3D V-Cache variants for unmatched gaming performance. 2022 Zen 4 (Ryzen 7000 series) Moved to the modern AM5 LGA socket, supporting DDR5, PCIe 5.0, and AVX512 instructions on a 5nm process. Zen 4/4c EPYC server processors with 98/128 cores became available. 2024 Zen 5 (Ryzen 9000 series) Delivers large instructions-per-cycle (IPC) gains and specialised hardware execution branches for artificial intelligence on a 4nm process. Zen 5c server chips have up to 192 cores! est. 2027 Zen 6 (Next-Gen platform.) Continues to push chiplet densities on the extended AM5 ecosystem. Year(s) Comments Processor siliconchip.com.au Australia's electronics magazine November 2026  21 FILAMENT YOU NEED, WHEN YOU NEED IT. EVERYDAY PRINTS. EVERYDAY VALUE. START PRINTING FOR LESS FROM ONLY MIX & MATCH ANY 10 FROM /ROLL /ROLL $ 17 95 $1345 . MORE MATERIALS. MORE COLOURS. MORE OPTIONS. FROM ONLY $ 19 95 /ROLL . FOR PRINTS THAT PUSH HARDER. SPECIALTY FILAMENTS. MATCHED TO THE JOB. FROM ONLY 2495 $ . /ROLL SEE THE FULL RANGE OF 3D PRINTING ONLINE jaycar.com.au 1800 022 888 jaycar.co.nz 0800 452 922 Prices shown in $AUD, and correct at time of publication but are subject to change. 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Jaycar reserves the right to change prices if and when required. 26 Silicon Chip R l e ix E L B G Ne o P G iven the popularity of my RGB LED ‘Analog’ clock design, and with some possible upgrades in mind, I felt a follow-up was worthwhile. While this new whitefaced clock doesn’t necessarily make the previous black one obsolete, it has some nice new features. I explained in the earlier article (May 2025; siliconchip.au/Article/18126) that I used standard RGB LEDs rather than addressable WS2812B ‘NeoPixel’ LEDs as they’re cheaper and easier to solder. I have since discovered cheaper ways to get these parts while designing the RGB LED Star (December 2025; siliconchip.au/Article/19372). That project used pre-soldered SMD LEDs, so we’re using them again. That means the Clock kit comes almost fully assembled. You just need to add a few bits like the Raspberry Pi Pico W that controls it, and away you go! You can see a video of the new Clock starting up and showing the time using Wi-Fi/NTP at siliconchip.au/Video/ NewRGBClock Using addressable LEDs means that we can have some more interesting effects on this clock. The previous one was limited to lighting four or five LEDs at a time as it used multiplexing; any more and they would become too dim. This one doesn’t have such a restriction. So, for example, the optional ‘sub-second’ chaser that runs around the face each second can have a trail. Having onboard Wi-Fi gives built-in support for network (NTP) time, meaning it will work and remain accurate anywhere you can get an internet connection. It also means you can fully control and configure the Clock from a computer, tablet or smartphone. That’s far more convenient than fiddling around with buttons. There’s also a lot of status and debugging information available over that interface, which opens in a normal web browser. You connect the Clock to a Wi-Fi network by powering it up, connecting to the hotspot it creates, then choosing your network and entering the password. As soon as it’s connected, it will try to get NTP time, and it should display an accurate time almost immediately. You just need to set your time zone if you aren’t in NSW, Victoria, Tasmania or the ACT to get the correct local time year-round. Our last RGB LED ‘Analog’ clock was popular. This one brings some style changes and updated features. It uses addressable RGB LEDs, with built-in Wi-Fi and NTP support, so you don’t need to add anything for timekeeping. It can also use a GNSS/GPS module as a time source. Australia's electronics magazine siliconchip.com.au ED ‘Ana Par t 1b yN ic V las l ho C l og ’ i ne n ock If you connect a GNSS/GPS module, you can choose whether the clock uses NTP or GNSS as the primary time source. It can fall back to the other source if the signal is poor or unavailable. If using a GNSS module as the primary time source, it can operate in Wi-Fi access point mode, so you can still configure and control it using a wireless device even if no Wi-Fi access point is available. Since the LEDs are fully addressable, you have more choices of colours. The previous clock let you use red, green or blue for the hour, minute and second hands. This one lets you choose any available RGB colour and brightness for any hand, plus the sub-second trail (if enabled) and the AM/PM LEDs, which can be disabled if you don’t want them. You can easily adjust the brightness remotely, or activate/deactivate and configure automatic brightness using the onboard LDR light sensor. The clock can be powered from a regular USB 5V supply or via a higher-­ voltage DC supply, up to 15V, using an efficient onboard regulator. The firmware we supply should do all this and more, but if a bug is discovered, a future update is released, or you want to try changing some of its features, the firmware can be updated remotely, over Wi-Fi. Still, for the most part, once the clock is set up, you can just hang it on your wall, power it up and leave it. It’ll keep the time accurate and correct year-round. Circuit details As you can see from Fig.1, there isn’t a great deal to the circuit, as most of the complexity is in the Pico W software. The 60 WS2812B addressable RGB LEDs are partially shown at lower left. They are connected in series, and the Pico W feeds them data in a daisy-chain serial fashion from its pin 6 (GP4) digital output via a 330W resistor. That resistor dampens any inductive spikes from the tracks between the Pico and LEDs, so LED1 isn’t damaged. There are numerous 5V supply bypass capacitors spread around the board: 22 × 100nF ceramic, 8 × 22μF ceramic and 4 × 220μF solid tantalum. These ensure that the WS2812B supplies remain steady even if many of them are switching on/off at the same time. siliconchip.com.au Australia's electronics magazine November 2026  27 they sit at +3.3V when the corresponding button is not pressed or 0V when it is. The Pico W just has to read the digital input state and perform some software debouncing to sense when a button is pressed. The optional GNSS module interface is a row of six pads labelled CON2. A typical GNSS/GPS module will run from a 5V supply and offer a 3.3V TTL serial interface, which makes it suitable for direct connection to the Pico W pins. A 330W series resistor on GP13, the serial output, provides protection in case that pin is accidentally shorted to ground or +5V. A 10kW pull-up resistor on the serial input pin, GP12, means that if nothing is connected to CON2, the Pico W doesn’t receive noise or garbage serial data. Pin 16 will be clamped below about 4V due to its internal ESD proWhat this RGB LED tection diode. Clock can do: While a 1PPS connection is proTells the time using 60 addressable RGB LEDs vided (to digital input GP10), it and two optional AM/PM LEDs isn’t used by the firmware. The White clock face with black writing software could be changed to Built-in Wi-Fi time (NTP) support The AM and PM use it, but we found it was Easy-to-build kit available with most components pre-soldered LEDs (LED61 & LED62) fine to just wait for a serial Each ‘hand’ can be configured with its own colour and style are driven similarly but from time update from the mod(as can AM/PM LEDs) different outputs and via ule before updating the Optional sub-second hand chaser, which can be customised their own resistors – output clock display. Second hand can be switched off GP5 for LED61 and GP28 Digital output GP14 Automatic brightness via LDR (can be configured/disabled) for LED62. That is purely drives an active-high Can run from USB 5V or 6-15V DC via an onboard DC/DC converter to improve the PCB layout; enable output. This is GPS/GNSS module can be used as a primary or secondary time source those two LEDs are close to simply driven high when Configurable time zone settings with automatic changeover the Pico W in the middle, GNSS time is enabled in Two configurable buttons for various functions while LED1-LED60 are around the configuration, or low All settings are adjustable over Wi-Fi using a web browser the circumference of the board. the rest of the time. Initial SSID/password setup via a Wi-Fi hotspot generated by So a track from LED60 to LED61 the Clock Power supply would be much longer than one Over-the-air firmware updates using a web browser from MOD1 to LED61. The rest of the circuit is Wi-Fi status page, full configuration and The LDR for auto-dimming is conthe optional power logging/debugging features nected in series with a 100kW resistor supply. I write to form a divider so that the ambient optional light brightness is translated to a voltage at pin 31 of the Pico W, which is an analog input. The Pico W uses its internal analog-to-digital converter (ADC) to convert that voltage to a number that can be used to adjust the LED brightness. The top of this divider (one end of the LDR) is fed from pin 35, which is the ADC voltage reference pin, meaning that supply voltage variations won’t affect this reading. It becomes a pure reading of the relative resistance of the LDR to the fixed 100kW resistor. Pushbutton switches connect between digital inputs GP15/GP16 and ground. These inputs are configured with weak pull-up currents, so 28 Silicon Chip Australia's electronics magazine siliconchip.com.au Fig.1: the Clock circuit is dominated by the 62 addressable LEDs (only some of which are shown) and the Pico W module, MOD1. The power supply at the top is optional; it can run from 5V USB power via the Pico W’s onboard socket if desired. because you can power the whole clock through a USB cable plugged into MOD1. That’s what we did during development, and it worked fine. Still, if you want to run it from a battery or a plugpack, an efficient switchmode power supply is provided. 6-15V DC is applied to CON1, and Mosfet Q1 provides reverse polarity protection as it will only connect the negative input to GND if the positive input has a higher voltage. The incoming supply is filtered and fed through a ferrite bead (for EMI suppression) to REG1, a switching buck step-down regulator. Its output is filtered by inductor L1 and some more capacitors, and a divided version is fed back to its FB pin to obtain a regulated +5V at the output. This goes through another ferrite bead and feeds the +5V rail if LK1 is shorted. LK1 is a closely spaced pair of pads siliconchip.com.au on the PCB, so you just need to short them if you want to power the circuit through REG1. This has the advantage that you can check REG1 is working before applying power to the 62 LEDs. That way, if something is wrong and the output voltage is too high, you won’t cook them! The Pico W is powered by +5V at its pin 39 VSYS input. It internally regulates this down to 3.3V to power the microcontroller, flash memory chip and other onboard parts. Construction The Clock is built on a double-sided white PCB coded 19101252 that’s circular and close to 200mm in diameter. Our kit includes a mostly assembled circuit board plus the remaining parts. We have done it this way partly to make it easier for constructors, but also because the cost of doing it this Australia's electronics magazine way is not much higher than simply providing all the parts. Fig.2 shows the front-side overlay. The parts mounted on this side are 62 WS2812B LEDs, two small tactile pushbuttons and a through-hole LDR (light-dependent resistor). Everything else is on the back. The only part you’ll need to fit on this side is the LDR, but don’t do that yet. Fig.3 is the back overlay. All the capacitors and resistors will already be populated, along with some of the semiconductors. The only parts you need to add are MOD1, REG1 and CON1 (if you’re using them) plus the optional GNSS/GPS module. If using that module, it can be stuck on the back with double-sided tape (antenna facing out) and its cable ends soldered to CON2. There are also pads to solder a few stiff pieces of wire so it can hang on a wall without the electronic parts November 2026  29 touching the wall, if that’s how you want to display it. Setting up the Pico W Before you start soldering the components, there are a few things to do. One is to program the Pico W. That is easy as long as you have a computer and a USB cable with a micro Type-B plug at one end. Download the firmware from siliconchip.au/Shop/6/3662 and extract the UF2 file from the ZIP. Uploading the firmware is basically the same procedure as copying a file to a USB flash drive. Plug the Pico W into your computer and its ‘flash drive’ should appear, named “RPI-RP2”. Copy the UF2 file you extracted earlier onto that drive, and after a few seconds, it will disappear. A little later, the LED on the Pico W should start flashing at about 0.5Hz. That means the firmware was loaded correctly. If the ‘drive’ doesn’t appear when you plug the Pico W into your computer, unplug it and hold down the white BOOTSEL button while plugging it back in. Once the firmware is loaded, it’s a good idea to get it connected to your Wi-Fi network. That way you know the Wi-Fi is working before you solder it. If you plan to use a GNSS module only for time then you don’t need to connect it to your network, but you may want to do that anyway to make changing settings easier. The alternative is to let it create its Fig.2: there are 62 LEDs on the front of the board, two buttons, the LDR and printed labels. The copper is covered with a white solder mask to match the white LED bodies. 30 Silicon Chip own Wi-Fi network that you can join only when you want to configure or communicate with it. In that case, it would be a good idea to at least check that you can connect to it before soldering. Using a computer, smartphone or tablet with Wi-Fi, search for the network named “RGBClock”. By default, there is no security, so you should be able to connect to it without entering a password. Open up a web browser and go to http://sc-rgb-clock.local – you should see a screen similar to that shown in Screen 1. If that doesn’t work, try http:// 192.168.4.1 (sometimes the name resolution can be slow or unreliable but it should work eventually). Note that the package orientation marking for the WS2812B LEDs is located on pin 3, rather than pin 1 Australia's electronics magazine siliconchip.com.au If you’ve gotten this far, the Pico W and its firmware are definitely working, and if you don’t plan to connect the Pico W to your Wi-Fi network (meaning you can’t use NTP mode), you can unplug it now and finish assembly. Assuming you do want to use NTP mode, or at least have the convenience of accessing it through your network, you might as well set it up now. If you know the SSID and password for your Wi-Fi network, enter them in the fields at the top of the web page that you’ve opened. You can also change the hostname (the name you use to access the Clock) if you want. Change the network mode to “Connect to network”, then click Reconnect. If you don’t know the network SSID, instead click on the “Scan for networks” button in the Wi-Fi section. A new window should open, and after a few seconds, it will be populated with networks. Click on the one you want to connect to. This will fill in the SSID field and take you to the password field, where you enter your network password, then click Reconnect. You can connect your computer back to your normal Wi-Fi network and access the Clock’s page via http:// sc-rgb-clock.local Now that you know the Wi-Fi settings are now correct, scroll down to the bottom of that page and click the Save button to save these new settings to flash. You can make more changes later. You are now ready to unplug the Pico W and finish assembly. Mounting the Pico W The Pico W can be surface-mounted onto the back of the clock PCB to make the clock as thin as possible. However, it’s unlikely you will be able to plug a USB cable into its socket if you do that. So if you are planning to power it from a USB cable, or want to debug it or upload new firmware via USB, you will need to mount it on some headers. Having said that, you can power it from a USB supply via CON1 if you need to, and it’s possible to update the firmware over Wi-Fi, so you can certainly use the clock with the USB Fig.3: on this side of the board, we have all the bypass capacitors for the LEDs, the Pico W control module, power supply and ancillaries. siliconchip.com.au Australia's electronics magazine November 2026  31 Screen 1: the RGB Clock can be controlled over Wi-Fi. Initially when connecting to it via http:// sc-rgb-clock. local you should see this screen. The Clock can also be configured using USB, as described in the panel overleaf. 32 Silicon Chip Australia's electronics magazine socket inaccessible. In that case, you will need to fit the REG1 chip later, or link it out if you’re going to run the clock from a source of regulated 5V DC (more on that later). Low-profile headers are tall enough to let a USB cable plug into the Pico W without making the clock assembly too deep, although you can use standard headers if you want. We supply low-profile headers in the kit, so you might as well use them. Start by soldering them to the Pico W module, inserted from the underside with the shorter ends of the pins sticking out the top. You can use a breadboard as a jig to keep them straight while soldering. Make sure you don’t fit them wonky or you might have trouble soldering the resulting assembly to the Clock board later. To save time, you don’t have to solder all 40 pins. We’ve marked all the pins that are actually used with triangles on the PCB silkscreen (also visible in Fig.3). You can refer to that and just solder the pins that are used. Those marked with “G” are ground pins, and theoretically you don’t need to solder all of those (but at least one or two). Still, you might as well do them all. Once you’ve finished that, add a little flux paste on each Pico W pad on the back of the PCB that you plan to solder, then rest the Pico W in place. Make sure it’s centred properly, then feed in some solder to a convenient pad from the side and melt it with the tip of your iron. Make sure it’s flowed onto both the PCB pad and pin, so that the module is no longer easy to move around. Check that the others are wellaligned, then solder one of the opposite pins. Proceed to solder the remainder. The module should be rigidly held in place once you’ve finished, despite only about a third of the pins being soldered. See the photo opposite for an idea of how it should look when finished. Testing The Clock isn’t finished yet, but it’s close enough to be able to test at this stage. Plug it into USB and you should see a green swirling pattern indicating that it has created a Wi-Fi access point but it can’t show the time yet. If you’ve already set up the Wi-Fi network, it should instead go to a red swirling pattern, then after about siliconchip.com.au 10-15 seconds, if it has successfully connected to your Wi-Fi network, it will change to mauve/purple. A few seconds later, the time display should come up. The LEDs should all work immediately. If you aren’t sure or want to check them, there are two buttons near the bottom of the web interface to test the LEDs. The first, “Test all LEDs”, lights them up white one at a time, starting with 12 o’clock and working its way clockwise around the clock face, then the AM/PM LEDs. It returns to the normal clock mode after that. The second, “Test colours”, lights up all LEDs red for 10s, then green for 10s, then blue for 10s, then returns to the normal clock mode. The time zone settings default to NSW/ACT/Vic/Tas, so if you’re elsewhere, the time may not be correct. You can access the setting page now, scroll down and change the time zone settings now, and the time should then be correct. Remember to save the changes when you’re happy. Remaining components Insert the LDR, pushing it in as far as you can while keeping it neat and centred. You’ll have to crank the leads a little; small pliers are helpful for that. Solder and trim the leads. If you don’t want to use the LDR, you can leave it off and simply disable automatic brightness control on the web page. If you’re going to feed in power via CON1, fit REG1 now, ensuring it is orientated as shown in Fig.3. Soldering it is a little tricky due to nearby components. We suggest adding flux paste to its pads before placing it, tack one pin, then once you’re happy with its alignment, add more flux paste on top. That will make bridges less likely. Clean the tip of your soldering iron, add a little solder and touch the tip to one pin, making sure to also touch the PCB pad so the solder flows onto both. Repeat until all pins are soldered. You’ll need to come in at a fairly steep angle to avoid D1 and the nearby capacitors. Inspect it with a magnifier. If you aren’t happy with any of the joints, or think the pins may be bridged, add more flux paste and use some solder wick coming in from above the chip to clean up the joints. Press your iron down onto the braid over the pins for a few seconds, then remove it. You should be rewarded with siliconchip.com.au v Parts List – Neopixel RGB LED ‘Analog’ Clock 1 Main PCB assembly (see below) 1 2-way right-angle header (CON1; optional) 1 GL5528 LDR (LDR1) 1 Pico W microcontroller module programmed with 1910125A.uf2 (MOD1) 2 20-pin low-profile header strips, 2.54mm pitch (for mounting MOD1) 1 AP5002 low-dropout buck regulator, SOIC-8 (REG1; optional) 1 200mm length of 0.7mm diameter tinned copper wire Main PCB assembly 1 double-sided PCB coded 19101252, 200 × 200mm (circular) with white solder mask 2 2A SMD ferrite beads, M3216/1206-size (FB1, FB2) 1 33μH 2.7A 12×12mm SMD inductor (L1) 2 6×3mm two-pin white SMD tactile pushbutton switches (S1, S2) Semiconductors 62 WS2812B addressable LEDs (LED1-LED62) 1 AO3400A 30V 5.8A N-channel Mosfet, SOT-23 (Q1) 1 BZX84C5V6 5.6V ±1% ¼W SMD zener diode, SOT-23 (ZD1) 1 BZG05C-5V6 40W peak zener diode, DO-214AC (ZD2) 1 SS34 40V 3A SMD schottky diode, DO-214AC (D1) Capacitors (all SMD M2012/0805-size MLCC unless noted) 1 220μF 25V SMD electrolytic, 8mm diameter 4 220μF 6.3V solid tantalum, SMB case 11 22μF 16V X5R M3216/1206 size 24 100nF 50V X7R 1 4.7nF 50V X7R 1 1nF 50V X7R Resistors (all SMD M2012/0805-size ±1% ⅛W) 2 100kW 1 10kW 1 6.8kW 1 1.3kW 1 1kW 4 330W Kit (SC7752, $85 + P&P): includes everything in the parts list, with the PCB already mostly assembled. GNSS modules are available separately: BZ-121 (miniature, 10Hz, $30) or VK2828U7G5LF (small, 1Hz, $25). When mounting the Pico W, we recommend using some headers so that it sits slightly above the PCB. If you want to mount it flush with the PCB, a USB connection might still be possible using a low-profile right-angle USB cable. Australia's electronics magazine November 2026  33 clean-­ looking solder joints on that side. Repeat if necessary. If feeding a regulated 5V supply to CON1, you can fit REG1 or use a short piece of wire to join the bottom two pads (4 & 5) to bypass it. You can fit a right-angle header for CON1 (plain or polarised/locking), or just solder wires there. You may want to avoid anything sticking through the front of the clock, or if it does project out the front, simply snip it flush with the face or the board while being careful not to damage the solder mask. Now apply 5-15V DC to CON1, paying attention to the polarity, and use a DMM to measure the voltage across ZD2. It should be close to +5V (say 4.75-5.25V) with the red probe on its cathode (striped end). If you get 0V or something else, or ZD2 is getting hot, REG1 may not be soldered properly, or your supply may be connected backwards. Switch off and check both. If you measure close to +5V, switch off and bridge LK1 with a solder blob, then reapply power and the clock should start up. Fitting a GNSS module If you want to use a GNSS/GPS module, you can connect and test it now. Find a good position for it on the back of the clock board, where the cable ends reach CON2 easily, and stick it in place with double-sided tape. Keep the antenna on the side away from the PCB. The copper planes on the PCB will reduce its sensitivity somewhat, but you can move it later if necessary. Depending on where you’re placing the clock, you may need a GNSS module with an external antenna connector Table 1 – common GNSS module connections CON2 BZ-121 VK2828 Neo-7M EN × Yellow × 0V Black Black GND RX White Green RXD TX Yellow Blue TXD +5 Red Red VCC PPS × White PPS to get a good signal (eg, a NEO-7M). Table 1 shows how to solder the wires for the three modules we sell. Others will be similar, but you’ll have to refer to the data sheet to figure it out. Only the 0V, 5V and TX connections are strictly necessary, although if your module has an enable pin and won’t run if it’s floating, you will need to connect that somewhere too. The EN pad is suitable as long as it’s active-high. Note that the TX and RX labels are from the point of view of the module and should match those functions on it (ie, the TX pin is what the Pico W uses to receive data and the RX pin is where it would transmit data). With the module wired up, power the Clock back up and switch the time source to GNSS in the user interface. If the module has an onboard LED (most do), you should see it light up. Once the Clock has connected to Wi-Fi, you should be able to access its page and see the GNSS status at upper-right. If it reads “no data”, that could mean the baud rate is wrong. The default is 115200, which suits the BZ-121. If your module needs a different baud rate (such as the VK2828, which defaults to 9600), enter it in the box. If you see the status change to “Receiving, no fix…” that means it’s correct now, so save the change. It can take upwards of 30 minutes for a module to get a lock on first poweron and that’s assuming there’s a good signal level, so you may have to wait a while before you see the status change to “Valid fix” or “Valid time”. Either should be fine for running the clock. If this isn’t working, there may be a wiring error. You can click the “GNSS Debug Window” button to open a window that should show the data coming from the module. If you aren’t seeing anything, or it’s garbage, and you’re sure the baud rate is correct, that could mean a wiring error. Unplug the Clock and check the wiring and that the module’s plug is inserted properly. Coming up next We decided to provide as much information in this article as possible to explain how the Clock works and allow you to get it up and running. However, we haven’t yet fully described how all the settings work, nor have we given any details on the firmware development and internal operation. The firmware is quite complex and could be useful as a starting point for another Wi-Fi based project using a Pico W or Pico 2 W. So if you’re interested in that, we’ll have more details in a follow-up article next month, along with the full usage instructions. In the meantime, if you’re curious about the firmware, the full source code is also available in the download SC package we linked to earlier. Configuring the clock via USB instead While the Wi-Fi & HTTP method (via a web browser) is the intended way to set up the clock, as it’s easier for most people, it’s also possible to set it up using a terminal program via its USB serial port. All the same settings are available that way. If you want to do this, plug it into your computer and check that a USB serial port is created. Connect to that using a program like PuTTY or Tera Term Pro (the baud rate isn’t important). Type “help” and press enter (a LF or \n character is expected after command). You should get a list of possible commands. Some relevant commands are: ● show settings – prints all the current settings to the terminal ● set x=y – change x to the setting you want to change (as per “show settings”) and y to the new value (true/false for boolean settings, a number for numeric; text otherwise) ● save settings – saves changes to flash ● wifi connect – connect to the network as configured via the SSID and password (will reconnect with the current settings if already connected) ● reboot If you’re not using a GNSS/GPS module (pictured above) as a time source, you can setup the clock via USB. Australia's electronics magazine siliconchip.com.au 34 Silicon Chip Sale ends November 30th Build It Yourself Electronics Centre® Y A D I R F K C BLA DEALS C 5162 ALL NOVEMBER! Brand name sound for FAR less $$$! SAVE $80 199 $ SAVE $50 139 SAVE $30 Three tools in one! 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Prices stated here in 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. *Devices for illustration pursposes only. 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. A long-delay timer from seconds to months Long-delay timers based on an RC circuit (eg, with a 555 timer) require very high-value, low-leakage electrolytic capacitors and high-value resistors. This results in poor accuracy because of the inevitable leakage, capacitor tolerance (often ±20% or more) and ageing. Some ICs are available for long-­ delay timing, such as the CD4060, DS1307 and TPL5010. However, they are still limited to delays up to a few hours. Using a microcontroller for long delays provides high accuracy in a small space, but a custom program is required. This design concept is loosely inspired by the colour codes used to show resistor values. By adding resistors to three analog input pins on a microcontroller, we can specify a three-digit delay code using just a few resistors. The delay is calculated as (10A + B) × 10C, with A, B & C each being a value between 0 and 9. Let’s say we want a delay of 1600 seconds (26m 40s). That’s 16 × 102 so we want A = 1, B = 6 & C = 2. In that case, we select R1a = 1.8kW, R1b = 10kW and R1c = 2.7kW. The microcontroller measures the three voltages, converts them to codes based on possible voltage ranges, then calculates and implements the delay, from 1 second up to 4,294,967,295s, which is over 136 years! The circuit is based on a PIC10F322, chosen as it takes up minimal space. To conserve power, the PIC spends most of its time in low-power sleep mode, waking up periodically to update a 32-bit countdown variable. The input-only RA3 pin is used as a pseudo-output via Q1, a logic-­ level N-channel Mosfet, which conducts only when the internal weak pull-up on RA3 is enabled. Since the internal ADC module used to measure voltages is limited to eight bits of resolution, with a 5V supply, the measurement step is 5000mV ÷ 256 (28) = 19.5mV. This is small enough to distinguish the ten possible values (plus uncertainty ranges from component tolerances etc) shown in Table 1. The assembly code occupies only 204 words of flash. So, it is also suitable for a PIC10F320 Table 1 – resistor values for each code Code R1x R2x Nominal voltage (5V supply) 0 1kW 10kW 0.455V 1 1.8kW 10kW 0.763V 2 2.7kW 10kW 1.063V 3 3.9kW 10kW 1.403V 4 5.6kW 10kW 1.795V 5 7.5kW 10kW 2.143V 6 10kW 10kW 2.500V 7 13kW 10kW 2.826V 8 18kW 10kW 3.214V 9 24kW 10kW 3.529V (simply uncomment the line “controller equ 10F320” and comment the succeeding line). The code has intentionally been left unoptimised to ensure it remains easy to understand, particularly for interested readers who wish to port it to a different microcontroller. This firmware relies on the internal LFINTOSC oscillator, which has a factory accuracy of ±25%. To improve timing accuracy, an external crystal should be used. However, this requires a microcontroller with at least eight pins. There’s no way to reset the timer; if you need to reset it, simply switch 5V power to the whole circuit. The firmware can be downloaded from siliconchip.au/Shop/6/3653 Hichem Benabadji, Oran, Algeria. ($75) Raspberry Pi Pico W BackPack The new Raspberry Pi Pico W provides WiFi functionality, adding to the long list of features. This easy-to-build device includes a 3.5-inch touchscreen LCD and is programmable in BASIC, C or MicroPython, making it a good general-purpose controller. This kit comes with everything needed to build a Pico W BackPack module, including components for the optional microSD card, IR receiver and stereo audio output. $85 + Postage ∎ Complete Kit (SC6625) siliconchip.com.au/Shop/20/6625 The circuit and assembly instructions were published in the January 2023 issue: siliconchip.au/Article/15616 Using YOLOE to identify a wide range of objects YOLO (You Only Look Once; https:// docs.ultralytics.com) is a fast way of identifying objects using a camera and a neural network. YOLO divides the image into a grid and uses the grid cells to detect bounding boxes and object classes. Each predicted box has a confidence score that combines how sure the model is and how well the box fits the object. Because everything happens in one pass, YOLO can run in real time, even on edge devices. While YOLO is trained to detect a fixed set of many objects, YOLOE allows you to select a few specific objects from a much larger visual world. YOLO is trained to recognise many objects but YOLOE focuses only on the objects you explicitly point out. YOLO works without prompts, whereas YOLOE operates by providing visual prompts that guide the model toward the desired objects. YOLOE is pre-trained on a large and diverse set of visual concepts. Instead of retraining the model, it analyses the geometric structure and visual patterns of the object you provide. By feeding a small number of example images from different angles, the model associates those patterns with a user-assigned object ID (not a name). From that point onward, whenever the model encounters a visually similar object, it produces the corresponding ID. This prompt-based identification is the core idea behind YOLOE. It is now possible to create a model that can identify a specific object, such as my MacBook charger, among many visually similar chargers. In the same way, a model can be created to detect people wearing glasses (like myself) or even a person holding a smartphone in their hand. The model becomes lighter and more focused, as it does not need to run a full, generic YOLO object detection pipeline. As a result, inference is significantly faster. It provides about five updates per second when running on a Raspberry Pi 5 (8GB). On a Pi 5, you can install the Python virtual environment with the following commands: python3 -m venv venv source venv/bin/activate pip install ultralytics pip install opencv-python-headless pip install numpy onnx torch pip install onnxruntime pip install torchvision pip install torchaudio If the object to be detected already exists within the pre-trained YOLOE model (for example, yoloe-11s-seg-pf. pt), we only need to provide a text prompt to specialise the model for those objects. This is demonstrated in “Text-Prompt ONNX Conversion. py” (download from siliconchip.au/ Shop/6/3624): from ultralytics import YOLOE model = YOLOE("yoloe-11s-seg.pt") names = ["Arduino", "pizza"] model.set_classes(names, model.get_text_pe(names)) model.export(format="onnx", imgsz=320) An example of YOLOE running and detecting various objects. 44 Silicon Chip Australia's electronics magazine For objects that are not present in the pretrained YOLOE model, a visual prompting approach is used. In this method, the physical appearance of the object is provided from two or three different angles and the model is visually guided to associate those appearances with an object ID. This is shown simply in “Image-Prompt ONNX Conversion.py”: from ultralytics import YOLOE from ultralytics.models.yolo.yoloe import YOLOEVPSegPredictor import numpy as np training_data = [ { "image": "image1.jpg", "box": [134, 182, 550, 510], }, { "image": "image2.jpg", "box": [158, 51, 346, 312], } ] These images can be sourced from the internet, captured using a mobile phone, or acquired directly using Image-Prompt-Capture.py. ImagePrompt-Draw-Box.py can then used to manually define bounding boxes for each object in every image. Using the mouse or trackpad, the user draws a rectangle tightly around the object in each reference image. Next time we run the resulting script, it will identify these objects with their ID numbers as set in the code. Within the inference code, a simple class mapping can be used to translate IDs back into human-­ readable labels. The “laptop-codes.zip” download includes modified code I ran on a Macbook to test YOLOE, as shown in the screen grabs. Object detection and recognition have traditionally been considered the domain of large datasets, long training cycles, and high-end GPU hardware. However, prompt-based vision models like YOLOE have dramatically lowered this barrier. One limitation is the inability to combine text-based and image-based methods within a single model. Since they currently rely on different binding mechanisms during model export, they must be handled separately. Bera Somnath, Kolkata, India. ($80) siliconchip.com.au Formaldehyde gas monitor Long-term exposure to formaldehyde, even at low levels, is dangerous. Considered one of the major indoor air pollutants, it is a colourless, strong-smelling gas. Common sources include pressed-wood products, paints, glues, wood-burning appliances etc. While basic portable formaldehyde detectors are available starting from about $10, some have low accuracy, while others are fake. This simple circuit allows you to choose the desired formaldehyde sensor according to the required accuracy and cost. Most of them provide numerical output over a UART or I2C interface, so you need a microcontroller to use them. This solution uses a readymade, low-cost development board based on the STM32C011 32-bit Arm Cortex M0+ microcontroller. The formaldehyde sensor I used is the SC11-CH2O, similar to the popular Winsen ZE08-CH2O. Other recommended sensors for DIY portable detectors are the Sensirion SFA30 and DFRobot Gravity HCHO. Measurements are displayed in real-time through a classic low-power Nokia 5110 LCD screen using the SPI protocol with a low memory footprint via a lightweight C++ software library (https://github.com/gavinlyonsrepo/ NOKIA5110_TEXT). Just connect the SC11 sensor UART to the microcontroller USART1 at 9600 baud 8N1 and the NOKIA5110 to SPI1 using DuPont cables. I used soft SPI so I could choose the STM32 pins myself (rather than being stuck with those allocated to the hardware SPI interface), and a system frequency of 6MHz for low current consumption. For the power supply, I used the STLINK-V2 module to test the prototype and it works fine. Even with the 3.3V for Vcc provided by the STLINK programmer, the SC11 reacts immediately to alcohol due to cross-­sensitivity. Nevertheless, the SC11 needs a power supply in the range of 4.2-5.5V to give useful ppm concentration values. This voltage range is dictated by the PCB mounted with the bare sensor: it contains a 3.3V LDO voltage regulator (MicrOne logo, code marking S2YP, in an SOT-23-5 package), a 32-bit GD32E230F4P6 microcontroller and a GS8552 rail-to-rail op amp. For those who want to avoid microcontrollers, simply connect a 5V analog voltmeter to the analog output pin of the SC11-CH2O module, and you are ready to use it as a formaldehyde detector. You should read about 3.3V in clean air. The galvanometer needle begins to oscillate more and more widely when you bring a cotton ball soaked in alcohol close to it. The firmware for this project can be downloaded from siliconchip.com.au/ Shop/6/3641 Mohammed Salim Benabadji, Oran, Algeria. ($60) Feeding line level audio to a mic input These simple resistive attenuators are all you need to reduce the level of line-level (nominally 775mV RMS) audio signals down to the much lower levels expected by a microphone input. Ensure phantom power is off, if the device supports it. If you need to block phantom power, add series capacitors (eg, 63V bipolar electrolytics). The balanced version simply attenuates both the ‘hot’ (pin 2) and ‘cold’ (pin 3) signals just like the unbalanced version, relative to the pin 1 signal ground. The 56kW upper divider resistors mean that the load on the signal source is more than 56kW, which should not be a problem for any typical line-level source to drive. The source impedance seen by the microphone input is the parallel combination of the two halves of the divider, which is a little less than 620W. That means even significant capacitance at the mic input shouldn’t result in any noticeable high-­frequency rolloff due to the low-pass filter formed with the source resistance. John Clarke, Silicon Chip. Circuit Ideas Wanted Got an interesting original circuit that you have cleverly devised? We will pay good money to feature it in Circuit Notebook. We can pay you by electronic funds transfer, credit or direct to your PayPal account. Or you can use the funds to purchase anything from the Silicon Chip Online Store. Email your circuit and descriptive text to editor<at> siliconchip.com.au siliconchip.com.au November 2026  45 Feature by Andrew Levido Motor Control Part 2: Brushless DC Motors Last month, we examined traditional brushed DC motors that use mechanical commutation to reverse the direction of current in the armature windings, producing sustained torque at the shaft. Now we will look at electronically commutated (brushless) DC motors and permanent-magnet synchronous motors. B Fig.1: a BLDC motor operates on the same principle as a conventional permanent-magnet brushed DC motor, but the windings are fixed to the stator and the magnets rotate with the rotor. to rotate, it is the reactive force that produces the torque. This time the rotor direction is anticlockwise, but to sustain this rotation, we still have to reverse the direction of current in the winding as the magnet poles pass the centre line. In a BLDC motor, we do this electronically, reversing the winding current every time one of the rotor poles passes a rotor position sensor at the 12 o’clock position, represented by the black dot. If we assume that the current directions shown in Fig.1 correspond to positive current, we should flip the current to negative when the south pole passes the position sensor and back to positive when the north pole passes it. If we reversed this and flipped the current negative when the north pole passes the sensor, and positive when the south pole does so, the motor would run in reverse. A single-winding motor like this is not very practical, as it will have high torque ripple. Practical BLDCs therefore use three or more windings, as shown in Fig.2. Three winding (or multiples of three) is the most common configuration; these are often called three-phase BLDC motors. The three windings, which I have coloured red, green and blue, respectively, are connected in a ‘star’ arrangement, with the common terminals of each winding marked C. The common connection is not usually brought out of the motor, so three-phase BLDC motors generally have three power terminals. Because the windings are connected in a star arrangement, current must always flow through two of them at once (for example, in through the U Australia's electronics magazine siliconchip.com.au rushless DC motors have everything in common with their brushed counterparts in terms of the method of torque production, electromechanical model and the equations that govern their operation. As a reminder, I have included the cross-section of a conventional brushed permanent magnet DC motor on the left of Fig.1. A torque is produced by the BIl force on the rotor windings acting over the radius of the armature. The force produced by the winding current flowing perpendicularly to the magnetic field of the permanent magnets is proportional to the rotor current, I, the field density, B, and the length of the winding, l. I have shown this force as blue vectors, plus the equal-but-opposing reaction force vectors in yellow. The reaction force is a product of Newton’s third law: when one object exerts a force on a second object, the second object exerts an equal and opposite force on the first. The best example I can think of is the force the 46 Silicon Chip floor exerts on the soles of your feet when you are standing. The force of gravity is pushing you down onto the floor, but at the same time the floor is pushing back with the same force. If it did not, you’d be in trouble! The commutator and brushes ensure that the motor current – coming out of the page in the left winding and into the page in the right winding – reverses as the windings pass the motor centreline. This way, the pulses of force, and therefore the torque, are always in the same direction, producing clockwise rotation. Brushless DC (BLDC) motor principles The brushless DC motor simply inverts this paradigm, as shown on the right of Fig.1. The windings are fixed to the stator and the field magnets are attached to the rotor. When current flows in the windings, a force is produced as before, but because the winding is fixed and the magnet free Fig.2: if the commutation points are determined by the rotor position, it is a BLDC motor, but if commutation is externally driven, it is a permanent-magnet synchronous motor (PMSM). terminal and out through the V terminal). With three windings, we need three position sensors set at 120° angles from each other, again shown by the black dots. In some motors, the sensors are positioned 60° apart and some additional logic is used to decode the rotor position. While the rotor is in position A, the U-phase is connected to the positive supply and the W-phase is connected to the negative. The rotor is forced to move clockwise, and as the centre of the north pole passes sensor 1, the U-phase is disconnected and the positive supply is applied to the V-phase. This state persists while the rotor moves through the 60° arc shown in diagram B until the south pole of the rotor passes sensor 3. Now the W-phase is disconnected and the negative supply is connected to the U-phase for the arc segment shown in diagram C. At the end of the C-segment, the north pole of the rotor passes sensor 2, the V-phase is disconnected and the W-phase is connected to the positive supply. This process continues, with the polarities of the windings changing every 60°, as shown in the diagram at the lower right of Fig.2. Is it really a DC motor? Before we get into the details of driving BLDC motors, we need to address the elephant in the room. One glance at the drive waveforms in Fig.2 confirms that we are absolutely driving this motor with a three-phase AC voltage – isn’t this therefore an AC motor, specifically a permanent magnet synchronous motor (PMSM), not a DC type? siliconchip.com.au The short answer is yes. There is no significant difference between the two in terms of the physical arrangement of the motor. The difference between a BLDC motor and a PMSM comes from the way you drive it. Purists might point to the shape of the back-EMF, but this difference is minor. In a motor designed as a BLDC type, the back-EMF tends to be trapezoidal in shape because the motor is meant to be driven by a square waves, while in a PMSM designed for mains operation, the magnetics are shaped so that the back-EMF is more-or-less sinusoidal. It is a subtle distinction, and in practice, it makes little difference. As an aside, I think the terms DC motor and AC motor are a bit outdated and unhelpful. In some respects, all motors are AC motors – the brushes and commutator in a conventional DC motor are converting DC to AC mechanically. Permanent magnet synchronous motors If you come at the same motor shown in Fig.2 from the PMSM perspective, you can choose to interpret the diagrams in another way. If you ignore the rotor for a moment, you can see that, if fed with the voltage waveforms on the right, the stator windings produce a magnetic field that ‘steps’ around the motor in each successive diagram. In diagram A, the field is horizontal, with the north pole pointing left. In subsequent steps, it rotates clockwise, 60° per step, always aligned with the unenergised winding. If the excitation were sinusoidal rather than stepped, the field vector would rotate smoothly around the stator once every Australia's electronics magazine cycle. This is exactly like the stator of an induction motor. Now consider the rotor. It is drawn with its magnetic field perpendicular to the stator field, the position where it experiences maximum torque. The rotor therefore is dragged around the stator, ‘locked’ to the rotating magnetic field. With a two-pole rotor such as this, the speed of rotation will be one turn for every excitation cycle. We can generalise this for any (even) number of poles Np to ω = 2πf ÷ Np in radians per second or n = 120f ÷ Np in rpm. A twopole motor fed with 50Hz mains therefore rotates at 3000RPM (157rad/s). The rotor speed is determined only by the frequency of the excitation voltage – hence the ‘synchronous’ term. The torque-speed characteristic is shown in Fig.3. As you might expect, for the nominal operating frequency fn, it is a vertical line, since the speed is unaffected by load up to the ‘pull-out torque’ (Tpo), where the rotor can no longer keep up with the rotating magnetic field and gives up trying. This is normally about 50% higher than the maximum rated continuous torque, labelled Tn in the diagram. If the torque is negative (the green part of the graph), the PMSM is acting as a synchronous generator. Given the November 2026  47 Fig.3: the torque-speed characteristic of a PMSM is a vertical line for a given AC frequency. The rotor current and therefore the torque produced is proportional to the torque angle, δ. speed equation above, it stands to reason that the only way to vary the speed of a synchronous motor is to change the frequency of the excitation. I have shown the torque-speed ‘curves’ for 25%, 50% and 75% of nominal frequency as dotted lines. The synchronous speed is reduced proportionally. The equivalent circuit looks a lot like an AC version of the DC motor’s equivalent circuit. In this case, R is the effective winding resistance and Xs is the effective inductive reactance of the stator windings. I write “effective” because in a balanced three-phase system, the magnitude of the flux produced by a given current is 1.5 times that which would be produced by a single winding. Xs is therefore 1.5 times the inductive reactance of one phase. Like a DC motor, the torque is proportional to the winding current (T = km • I), where I is the RMS value of the phase current and km is the constant of proportionality. Things get a bit more complicated from here. Firstly, we cannot ignore the inductive reactance like we did for the DC motor. In fact, it is usually much higher than the resistance, so we ignore that instead. Secondly, we have to contend with a potential phase difference between the excitation voltage and the back-EMF. This phase shift comes about because the angle between the magnetic axis of the stator and that of the field varies as the load torque changes. At low load, the angle between the rotor and the field is near zero, but as the torque increases, so does the angle. In Fig.2, it is shown at 90°, the angle it would be at maximum torque (just before pullout). This angle, δ (delta), is sometimes called the torque angle. The current flowing in the equivalent circuit is therefore the difference between the supply voltage and the back-EMF, divided by the inductive reactance and multiplied by the sine of the torque angle to account for the phase shift. Putting this all together gives us an expression T = km•([V – Eb] ÷ Xs)•sin(δ). For a given frequency, the back-EMF is fixed (because the motor is synchronous), so the only variable we can easily control is the voltage. We can actually control δ using a complex technique known as field-oriented control, but I will save that for another article, because it applies to other AC motor types too. If we apply a fixed voltage and frequency to the motor, it runs at some constant speed. As the load torque varies, the torque angle, and therefore the current, changes. One important thing this equation tells us is that, for a given torque/current, we have to reduce the applied voltage as the frequency drops. This is because the inductive reactance and back-EMF both reduce with frequency. If we don’t reduce the voltage more-orless in proportion, the current would increase and the motor would quickly burn out. Because of their rotor inertia, synchronous motors can be hard to start unless the frequency is ramped up gradually so the rotor can ‘keep up’ with the accelerating field. Industrial-sized permanent magnet synchronous motors – those intended for direct connection to the mains – usually have conductive bars embedded in the rotor and actually start as induction motors until the rotor gets near enough in speed to lock into the rotating field. BLDC/PMSM drivers Interestingly, you can drive this one type of motor in two different ways and get two different sets of performance characteristics. If you use the rotor position to determine the commutation points, the motor has all the characteristics of a DC motor that we described last week, including the equivalent circuit, equations and torque-speed characteristics. If you perform the commutation independent of rotor position, the same motor has the characteristics of a synchronous motor with the equivalent circuit, equations and torquespeed characteristics described above. This is not always made clear in either the textbooks or the application notes for motor drivers. Fig.4: the power electronics to drive three-phase PMSMs and BLDC motors is identical. You can use either voltage-mode or current-mode modulation with a variety of modulation schemes. 48 Silicon Chip Australia's electronics magazine siliconchip.com.au The power electronics required to drive these motors are identical for either case, so let’s get that out of the way first. Fig.4 shows a typical power electronics drive circuit for a threephase BLDC or PMSM. This is just a classic three-phase full bridge that is capable of driving current into the motor windings in either polarity. I don’t have much more to say about this except to note that the voltage, or current in the case of a current-mode modulator, is normally controlled by pulse-width modulation from a fixed DC supply, as shown at the right of Fig.4. I have shown two types of modulation: square modulation, which is identical to that shown in Fig.2 except for the PWM to control voltage, and trapezoidal modulation, which more closely matches the back-EMF waveform and produces smoother torque and often lower acoustic noise. You can use sinusoidal modulation or field-oriented control too. The rest of the modulator is where the difference lies. In the case of a BLDC driver, the commutation is controlled by position sensors, usually Hall-effect sensors embedded in the motor or a resolver on the shaft. The modulator input is a signal proportional to the desired operating voltage for a voltage-mode modulator, or current for a current-mode modulator. In the case of a PMSM, the modulator input is the desired frequency/ voltage. Fig.5 shows the typical control schemes for both types of drive. These are both very similar to the DC drive controllers we looked at last time, with an inner current control loop and an optional outer speed control loop. You can also add a position control loop around both to create a servo drive. The BLDC modulator requires position feedback from the motor, adding complexity, but this can also be used to provide speed feedback. You will need an additional speed sensor for a PMSM if you want to close the speed loop. If you are using a motor with rotor position sensors, you can use them for speed sensing, even though they are not being used for commutation. You can potentially derive the commutation points for a BLDC motor by looking for a zero-crossing in the voltage across the unenergised winding (assuming you have access to the winding star connection). I’m not sure siliconchip.com.au Fig.5: a BLDC modulator requires rotor position feedback, but a PMSM modulator does not. Rotor position feedback also provides speed information. Fig.6: these extracts from the L6235 data sheet show how the current-mode modulation works and how easy it is to add a speed control loop. Australia's electronics magazine November 2026  49 how practical this is, given you can get more-or-less any motor characteristic you want out of a PMSM with field-­ oriented control, with or without rotor position sensors. A practical example The L6235 BLDC motor control chip is a good example of an integrated driver designed for BLDC applications with Hall-effect position sensing. I have not personally used this chip, but I think is serves as a good example of what’s out there. It includes a three-phase Mosfet bridge that can supply 2.8A continuous (5.6A peak) with a supply in the range of 8-52V, so it is suitable for 12V, 24V or 48V motors. It includes the Mosfet drivers and most of the charge pump necessary to power the high-side drivers. You do have to provide a couple of diodes, a couple of capacitors and a resistor to complete the high-side power supply. There are three inputs for Hall-­effect or other position sensors, which can be either arranged 120° apart like those I have shown in Fig.2, or 60° apart. The IC includes the additional decoding necessary for 60° sensors. The L6235 contains a monostable multivibrator with a programmable pulse width that is connected to one of the Hall-effect sensor inputs. This provides a fixed-width pulse train at a frequency proportional to rotor speed, which is very handy for speed feedback. The Hall-effect sensors manage the commutation but the output is modulated by a current-mode controller, as shown in the diagram taken from the data sheet, at the top of Fig.6. The Mosfet bridge current is measured across the external shunt resistor labelled Rsense and is used to drive a constant off-time current controller. Recalling that only two windings in series are energised at any time – so only one low-side Mosfet is on at any given time – the voltage across the shunt will be proportional to winding current. When this rises to a level determined by the voltage on the Vref pin, the flip-flop is set and the external capacitor (Coff) begins to charge from a 5mA constant current source. ▶ 50 Silicon Chip Fig.7: BLDC and PMSM motors come in many different configurations, including ‘outrunners’, where the rotor spins outside the stator. Australia's electronics magazine During this time, the Mosfet drive is inhibited, so the winding current begins to fall as the bridge freewheels. When the voltage on Coff reaches 2.5V, the comparator resets the flipflop, and the Mosfet drive is switched on again. Coff discharges via Roff, ready for the next cycle. The current waveform is therefore triangular, with the peak-to-peak ripple determined by the programmed off-time and the peak current determined by the voltage on the Vref pin. This chip therefore incorporates the modulator and the current controller, so it is good value for money. The L6235 data sheet shows that it is easy to add a speed control loop, as shown at the bottom of Fig.6. This simple Type-I compensator has a single pole at a frequency determined by C1 and R4. I am not 100% sure what Cref1 is doing – another pole is not strictly necessary – but I suspect this network may just be to provide a bit of high-­frequency filtering at the reference input. Another nice feature of this chip is that it uses synchronous rectification during the freewheeling phase. For example, when a low-side Mosfet switches off, the current it was carrying would normally commutate to the body diode of the corresponding highside Mosfet. The L6235 switches this high-side Mosfet on after a 1µs delay, to reduce the freewheeling losses since the voltage drop due to the on-resistance of the Mosfet is much lower than that across the diode. That’s a nice touch. There are plenty of other drivers out there that suit both BLDC and PMSM applications. Many (perhaps most) include just the bridge driver and some protection circuits, leaving the production of the drive waveforms up to an external microcontroller. Motor configurations Just like with DC motors, BLDC/ PMSM motors come in an almost bewildering variety of configurations, optimised for various applications. The wound-stator type, shown at the top of Fig.7, is generally used in highspeed, high-torque applications. The rotor slots are skewed so that torque production is relatively smooth and the rotors can be small so their moment of inertia is low. I have shown the rotor with four siliconchip.com.au poles, although in reality these motors are often made with many more. The majority of electric vehicle motors are of this type, so a lot of design effort has gone into them, particularly in optimising the magnetics and efficiency. Their performance is mind-­boggling. A typical EV motor can deliver 200kW or more at the shaft, while weighing just 15kg. They usually operate from 400-800V and can draw several hundred amps per phase. Even with their high efficiency, at this power level, they require water or oil cooling. Less-demanding applications often use a salient-pole stator, like that shown in the second part of Fig.7. Each winding is replaced by a pole-pair on opposite sides of the rotor. Magnetically, this is more-or-less identical to the wound-stator design, but it is cheaper to produce. On the downside, salient-pole motors don’t make quite as good use of the space inside the motor, so they tend to be a little less efficient. Photo 1 shows a typical high-performance salient-pole BLDC motor manufactured by Maxon. This model is 32mm in diameter and has integrated drive electronics. The motor shaft is just visible behind the edge of the PCB. There is no law that states that the rotor has to be inside the stator. In many cases, it is convenient to have the stator inside the rotor – an arrangement known as an outrunner. These can be wound-rotor types, like the third diagram, but more often they have salient poles, like the fourth diagram. Out-runners are often used when the main requirement is torque rather than speed, although some are capable of pretty high speeds too. The rotor has a relatively high moment of inertia due to its larger radius, so this type of motor is mostly used in less dynamic applications, like cooling fans. This type of motor has become the go-to motor for drones because its speed and torque are well matched to propellers, and they are relatively lightweight. You also see salient-pole outrunner PMSMs used in the hub motors of e-bikes and e-scooters. All the motors I have shown here are three-phase types, but there is no reason why that always has to be the case. Fig.8 shows one common alternative configuration. This is a single-­ phase motor with two pole pairs, like that often used in small cooling fans found in electronic equipment. siliconchip.com.au The four windings are all connected in series in such a way that a positive current produces the current directions and resulting magnetic polarities as shown. A negative current would produce the opposite current direction and magnetic polarity. These motors generally have one Hall-effect position sensor (the black dot) that drives the commutation. The current direction is reversed every time one of the four permanent magnet poles passes the sensor. If the rotor is moving, its moment of inertia ensures that it passes each pole and triggers the sensor so it is attracted to the next pole in turn. The challenge with single-phase motors like this one is starting, or at least starting them in the right direction. In the position shown in the figure, there would be no torque on the rotor if the poles were symmetrical. A symmetrical pole has an even distribution of flux density across it, so both sides of the winding see the same BIl force and they would cancel out. This would happen for all four poles, so no net torque would be produced. This type of motor therefore has the asymmetrical poles you can see in the diagram. The flux density across each pole is slightly stronger on the thicker side. This means there is slightly more BIl force on one side of each winding in all four poles. You can use the right-hand palm rule to satisfy yourself that these net forces all point counterclockwise with the current flowing in either direction, so there is always a small clockwise reactive torque bias on the rotor. This is enough to get the rotor moving in the right direction. The asymmetry means that this type of motor can only run in one direction, but that is not a problem for cooling fans. These motors are a wonder of lowcost design. Photo 2 shows the stator of a motor taken from a 40mm fan that gave its life in the interests of science. You can clearly see the asymmetric salient poles and the windings, which are just one length of enamelled copper wire wound around each pole in succession. At the top of the motor is the combined Hall-effect sensor and driver chip. This has just four pins, two for the incoming power and two for the stator windings. That is all there is on the single-­sided phenolic PCB – there Australia's electronics magazine Photo 1: this is a nice example of a salient-pole BLDC motor with integrated drive electronics. Source: Maxon International AG. Photo 2: this wonder of low-cost engineering is the stator from a 40mm cooling fan. Note that one end of each stator pole is slightly thicker than the other. Fig.8: single-phase BLDC motors, such as those used in cooling fans, have asymmetric poles to provide a small torque bias. This ensures they start reliably and spin in the right direction. is not even a decoupling capacitor in sight! Brushless DC and permanent-­ magnet synchronous motors are rapidly taking over from brushed DC motors – and that’s no surprise given their versatility. One motor type that can be used for anything from a powerful and advanced EV motor to a superlow cost fan motor. Next month, I will look at stepping or stepper motors – a very popular motor for position control applications, like in many 2D and 3D printers. They operate on a different principle: SC that of variable reluctance. November 2026  51 Tim Blythman’s Portable This project is based on a circuit we published in Circuit Notebook. It uses an inductor to detect electromagnetic fields and convert them into audio so that they can be studied more easily. It fits in a tiny case, using a wand probe to make a compact yet useful device. EMF Probe 52 Silicon Chip Australia's electronics magazine T his project uses an inductor to detect electromagnetic fields and convert them into audio so that they can be studied more easily. It fits in a tiny case, using a wand probe to make a compact yet useful device. It is based on a circuit we published in Circuit Notebook. The circuit that this project was inspired by was published on page 87 of the June 2025 issue as “Non-­ contact diagnostic tool detects electromagnetic fields” (Circuit Notebook; siliconchip.au/Article/18320) by Dr George A Davidson. We have made some changes to the circuit, but the inspiration is clear. Like some of our other small projects, we figured that we could make it fit in the tiny enclosure we used for the USB-C Power Monitor project in August & September 2025 issues (siliconchip.au/Series/445), available from Altronics (Cat H9004). Circuit details Fig.1 shows the circuit diagram. The sensing device is inductor L1. Dr Davidson suggests a part from a failed switch-mode power supply of around 1mH, with a 6W DC resistance. We decided to pick an off-the-shelf part so that we could have some certainty in its performance. We found an unshielded part that worked quite well; the lack of shielding is actually helpful in this application. IC1 is a dual, low-power, rail-to-rail op amp. One lead of the inductor is connected to the non-inverting input of one of the op amps in the package (IC1a), along with a mid-rail bias. The other lead of L1 is connected to the inverting input via a 1μF capacitor. 100kW log-profile potentiometer VR1 provides feedback from the op amp output back to the inverting input. L1 generates currents from nearby electromagnetic fields and these tend to move the inverting input away from the bias point. The op amp output produces a voltage to cancel this out. When VR1 is set to a high resistance value, the output voltage swing needs to be higher to provide enough current through the feedback resistance to counteract the current that L1 generates. Thus, VR1 provides a gain or level setting. The output of IC1a is AC-­ coupled and again biased to the midrail point before being fed to the other siliconchip.com.au op amp in IC1, IC1b, which is configured to provide 11× gain, adding a second gain stage compared to the Circuit Notebook version. In the Circuit Notebook submission, a 4518 dual BCD counter IC is used to provide ÷10 and ÷100 frequency outputs. This part is becoming scarce, but fortunately, the venerable 4017 Johnson decade counter is still widely available. The output from the second op amp is connected to the CP0 pin of IC2, the first of two 74HC4017 decade counters. Both counters are configured to operate normally by having their MR and CP1 pins pulled low. The frequency of the carry output from pin 12 is divided by 10 and fed to IC3, where it is again divided by 10 in frequency. Naturally, the op amp output signal from pin 7 of IC1b must be of a high enough amplitude to be recognised by the digital input of IC2, so lowlevel signals may not be detected by this part of the circuit. The 74HC type (rather than a 4017B) is necessary to allow correct operation since this circuit runs from just 3V. The output from IC1 is fed to headphone socket CON1 via a 220W resistor and a 10μF AC-coupling capacitor. The outputs from IC2 and IC2 have 1kW series resistors and are switched by momentary switches S2 and S3, allowing the divided signals to be individually gated and mixed into the audio output. Jack socket CON1 is a switched type, allowing the output to be directed to a piezo transducer (PIEZO1) when no headphones are plugged in. Finally, a 1MW resistor is provided across the Silicon Chip kcaBBack Issues $10.00 + post $11.50 + post $12.50 + post $13.00 + post $14.00 + post $15.00 + post January 1997 to October 2021 November 2021 to September 2023 October 2023 to September 2024 October 2024 to August 2025 September 2025 to May 2026 June 2026 onwards All back issues after February 2015 are in stock, while most from January 1997 to December 2014 are available. For a full list of all available issues, visit: siliconchip.com.au/Shop/2 PDF versions are available for all issues at siliconchip.com.au/Shop/12 We also sell photocopies of individual articles for those who don’t have a computer audio output to keep the output side of the 10μF capacitor biased to ground, helping to avoid nasty clicks occurring when the headphones are plugged in. Power supply The circuit’s power supply is BAT1, a 3V lithium coin cell. This is another difference from the Circuit Notebook entry, which used a 9V battery. S1 is a momentary tactile switch that controls power to the rest of the circuit. Using a momentary switch means there is no chance of accidentally leaving the circuit switched on and draining the battery, which has a low capacity. The switch feeds a 10W series resistor and a 10μF capacitor; 10μF is a reasonable amount of bypass capacitance for a simple digital circuit like this. This arrangement provides some filtering and thus softens the clicks that occur when the circuit powers on and off. We’ve also found that a decent amount of filter capacitance (more than the few hundred nF that the ICs require for normal operation) can help to filter out the high-current bursts that can affect coin cell longevity. The filtered supply voltage feeds the three ICs, each of which has a 100nF bypass capacitor. The mid-rail bias voltage is derived using a pair of 100kW resistors across the supply; this is stabilised by a 1μF capacitor and is used to bias both of the non-inverting op amp inputs. Current consumption and cell life We’re using a rail-to-rail output op amp, so the signal delivered to CON1 is limited to around 3V peak-to-peak by the supply voltage; this corresponds to just over 1V RMS. With a pair of standard 32W headphone drivers in parallel through a 220W resistor, the peak output load is just under 250W, meaning just over 4mA can be delivered. The IC2 and IC3 output currents via the 1kW resistors will peak at around Fig.1: using the two stages from a dual op amp, the Probe amplifies electromagnetic fields detected by L1 and feeds them to a headphone socket, CON1. Two counter ICs optionally divide the signal down so that higher frequencies can be detected. siliconchip.com.au Australia's electronics magazine November 2026  53 1mA, although it is expected that only one will be active at a time. Since IC2 and IC3 are CMOS devices, their contribution to current draw is negligible, as is that of the bias divider. The total quiescent current is expected to be a few milliamperes at most. The absolute maximum expected draw is around 5mA. When not near any electrical equipment, we found that the Probe usually drew well under 1mA, even with VR1 fully clockwise. Whilst probing various devices around the workshop and office, the most demand we could place on a brand new cell (measuring 3.2V) was around 3.5mA with all three buttons depressed. At this level, the sound in the headphones was quite loud. The piezo transducer has a much higher impedance, so it will draw less current. However, we also found it did not reproduce low frequencies well and was generally quite soft and difficult to hear except around strong sources. The expected battery life is hard to predict and will depend on usage and even the environment being probed. With occasional use, we would expect the cell to last a few years, if not longer. The current draw when the unit is not being used will be no more than the cell’s self-discharge, since the switch disconnects the circuit completely. The ICs are rated to operate down to 2V or lower, so the unit will continue operation until the cell is quite flat. When that happens, you should notice it as there will be a reduction in the output volume. Case preparation We recommend completing the case cuts before assembling the PCB. That way, the blank PCB can be used as a template, and you can check that everything looks correct as you go. Refer also to Fig.2, the drilling diagram. The two holes are round and can be made with a drill. We find that clean holes are much easier to achieve with a step drill. The smaller hole (for the headphone socket) is right at the top edge of the enclosure, so we suggest attaching the lid while making this hole, as this will provide a uniform surface for the drill. You don’t want it to ‘walk out’ as it cuts through the edge of the case. The larger hole (for the potentiometer) will be partially covered by the 54 Silicon Chip Fig.2: use the bare PCB to help mark and check the drill locations; these two hole are required in the end of the case for VR1 and CON1. Before drilling the smaller hole for the headphone socket, attach the plastic lid to the enclosure to prevent the drill bit from wandering. skirt of the knob once it is installed. Thus it won’t matter too much if a slightly larger hole is used for the potentiometer. We’ve also designed a 3D-printable case that includes the holes in the correct locations; this can be downloaded for free from the Silicon Chip website at siliconchip.com.au/Shop/11/3650 Assembly All parts are fitted to a 40 × 100mm PCB coded 04109261, which forms the front of the case in the assembled unit. The case must be used to ensure that the coin cell is fully contained and cannot be removed by children. During construction, refer to the PCB overlay diagram (Fig.3) to see which parts go where. The parts are mostly M3216 (1206) size passives (3.2 × 1.6mm) and SOIC (small outline IC) chips, so it is not difficult to assemble. Make sure you have the usual SMD equipment and tools such as flux paste, solder-wicking braid, a magnifier and tweezers. You’ll also need a suitable cleaning solvent for your flux; isopropyl alcohol is a reasonable general-­purpose option. Start with the three ICs. Apply flux to their pads on the PCB. Rest each IC in place, then check carefully that its pin 1 marking is correctly orientated before proceeding. Clean the soldering iron tip, then add a small amount of fresh solder. Tack one lead and use tweezers to ensure the part is located symmetrically over the pads and flat against the PCB, readjusting it while heating the initial solder joint as needed. When you are happy with the location, solder the remaining leads, adding solder to the iron and cleaning the tip as necessary, then refresh the initial joint with a dab of flux and some heat. Next, fit the capacitors using a similar method, keeping in mind that they will not be individually marked. The two 10μF parts will probably be the thickest, so fit them next, followed by the 1μF capacitors and then the 100nF capacitors. Next, mount the 11 fixed resistors, which should be marked with scientific notation style codes indicating their values (eg, 1kW = 102 or 1001). Check each against the PCB silkscreen and the Fig.3 overlay diagram. Fit the cell holder next, making sure that the wider opening faces towards the edge of the PCB. Be sure to add generous amounts of solder to the leads to provide mechanical strength. Now is a good time to clean the flux from the PCB, since the remaining components will be better off not being immersed in solvent solution. Soak up as much solvent as possible (eg, using a lint-free cloth) so it does not leave a residue as it evaporates, then allow the board to dry before proceeding. You should not need additional flux for the remaining components, since they have larger leads. Slot the headphone socket into its locating holes on the PCB and solder each lead in place. Place the piezo transducer For the case you can either 3D print your own (shown in dark grey) or use a commercial 80 x 40mm enclosure (shown in black). Australia's electronics magazine siliconchip.com.au with its hole near the matching hole in the PCB and solder both leads. The tactile switches are reverse mounting types, so they mount upsidedown with their stems protruding through the holes in the PCB. Tack solder one lead on each and flip the board over to check the alignment. Any misalignment here will be visible from the outside of the Probe if the switches are not centred, so take time to make sure that they look right. Once you are happy with the switch placement, solder their remaining leads. Like the cell holder, use a good amount of solder to add mechanical strength. VR1 is a through-hole part and we have added solder mask over the external pads to improve its appearance. To keep this tidy, we recommend carefully trimming the leads of VR1 so that they are just flush with the top of the PCB before soldering. That will still leave enough lead for the solder to adhere to. Take care that VR1 is square with and flat against the PCB by working with one lead until the part is correctly placed. L1 is another through-hole part. To add some length to the Probe, we left the leads near their full length. Solder the leads into the pads on the PCB and then bend the parts sideways to extend the probe outwards. The exposed leads will be covered with heatshrink tubing later. At this stage, the Probe is functionally complete, and you can insert a cell to test it out. The piezo is quite soft and will only be useful in the presence of strong sources, so headphones are recommended. Make sure that the volume setting is low (anti-clockwise) before pressing the ON button. This will avoid sudden loud noises. Start in open space, away from any electrical equipment. You should hear a background hiss as you slowly raise the volume. You might notice the pitch reduce as you do so due to the gain-bandwidth limit of the op amp. You should find a moderate setting that provides sufficient volume. Now you can bring the probe nearer to electrical equipment (but don’t touch it!) and hear the sound intensify. While holding the ON button, try the ÷10 and ÷100 buttons. Near strong sources, you should hear a low clicking or buzzing if these stages are working correctly. siliconchip.com.au Fig.3: with ample PCB space, the silkscreen labels are quite clear. Many constructors will be able to complete assembly using them alone. Parts List – Portable EMF Probe 1 double-sided PCB coded 04109261, measuring 40 × 100mm 1 80 × 40mm enclosure [Hammond 1551KBK, Altronics H9004] 1 surface-mounting (CR)2032 cell holder (BAT1) [TE Connectivity BAT-HLD-001] 1 CR2032 lithium coin cell 1 3.5mm switched TRS jack socket (CON1) [PJ-328 or SJ-3524-SMT] 1 bobbin-style 5mm unshielded 1mH inductor (L1) [Bourns RLB0608-102KL] 1 9mm square SMD piezo transducer (PIEZO1) 3 reverse-mount SMD 6mm outline tactile switches (S1-S3) [Adafruit 5410] 1 9mm right-angle log profile 100kW potentiometer (VR1) 1 knob to suit VR1 1 5cm length of 10mm diameter heatshrink tubing 1 small piece of insulating tape (black electrical tape or Kapton tape) Semiconductors 1 MCP6272(T)-E/SN, MCP6002(T)-I/SN or -E/SN dual op amp, SOIC-8 (IC1) 2 74HC4017 SMD decade counters, SOIC-16 (IC2, IC3) Capacitors (all M3216/1206 size X7R 50V SMD ceramic except as noted) 2 10μF 25V 3 1μF 3 100nF Resistors (all M3216/1206 size SMD ⅛W ±1%) 1 1MW 4 100kW 2 10kW 2 1kW 1 220W 1 10W We recommend not cutting the leads of the inductor short. This will provide extra length to the wand, and we expect the flexible leads will be more forgiving in the unlikely event that the Probe is dropped. Heatshrink tubing completely encloses the end of the Probe, protecting it from inadvertent contact. Kit (SC7715, $30 + P&P): includes all parts except the case, cell and insulating tape. Australia's electronics magazine November 2026  55 The Portable EMF Probe fits neatly in the palm and has three pushbuttons for operation. A volume control and headphone socket are available at the end opposite the probe wand. All components mount directly to the PCB (which also forms the lid of the enclosure), with most being SMD types. Potentiometer VR1 and inductor L1 are through-hole types but don’t protrude through the front of the PCB. If your Probe is not behaving like this, remove the cell and check things like solder joints and the orientation of the ICs. Also check that the cell is fitted correctly (+ side up) and that it is not flat. When you are sure it is working, apply heatshrink tubing over the wand and inductor. Squeeze the end of the heatshrink with pliers while it is soft to ensure that the end is sealed off. Even with this protection, the Probe should not be used near exposed mains wiring. Place a small piece of insulating tape over the exposed tips of VR1’s leads. There are no dangerous voltages present, but contact with these pads might couple signals into the Probe and interfere with its output. You might think that we’re making a bold style statement with the dashing white stripe on the front of the case. While that might be true, the extra silkscreen ink also provides a further layer of insulation over the small number of copper traces that need to run on this side of the PCB. Install the PCB into the case now. You should be able to slot CON1 and VR1 through the holes at an angle to get the PCB into place before securing 56 Silicon Chip with the included case screws. Fit the knob to VR1 to complete the assembly. Using the Probe There are many different devices that can be tested using the Probe and the results may vary from what we found. Remember that the detection of strong electromagnetic fields is not always a good sign for the health of some equipment. Dr Davidson gave the example of diagnosing faulty switchmode power supplies. In such devices, the current should be travelling in tight loops that should not emit much of an electromagnetic field. Points that are strongly radiating may be symptomatic of a fault. On the other hand, mains devices will radiate at 50Hz while they are drawing current, so that can be a sign that they are working correctly. RF sources Devices such as RF transmitters are designed to radiate, so if you pick up a strong signal, that can indicate correct operation rather than a failure. Passing the Probe over a mobile phone gave a strong signal (ticking sound) at one location, hinting at the location of Australia's electronics magazine the transmitting antenna. Even though the transmission frequency is well beyond the upper limit of the audible frequency range (~20kHz), the Probe will detect artefacts due to modulation of the radio signal. These might be heard as clicking or buzzing noises. We also found that wireless mobile phone chargers (Qi chargers) gave off a characteristic sound that consisted of brief pulses of a fairly pleasant tone (rather than a harsh buzz). So the Probe can be quickly used to check that these sorts of devices are working correctly. In this vein, you could use the Probe on working equipment to establish a baseline for normal operation. You might be able to detect impending failures if the sound changes. Summary While not a rigorous diagnostic tool, we found the Portable EMF Probe useful for providing insight into the electromagnetic fields that are present around many types of equipment. As Dr Davidson suggests, it has great educational value in providing an intuitive understanding of electroSC magnetic fields. siliconchip.com.au New PICs and free compilers Microchip VS Code IDE We use microcontrollers from Microchip Technology in many of our projects; for over 15 years, we have used the MPLAB X IDE to develop the firmware. Now Microchip has released an MPLAB Extension for VS Code IDE. We’ll look into that, plus the latest microcontroller peripherals from Microchip. by Tim Blythman A n IDE (integrated development environment) is a program that can be used to develop software. Many years ago, we used separate text editors, compilers and programming apps to do this task, but an IDE brings these together into a single, integrated environment, making development easier (many IDEs also include an in-circuit debugger). There are also IDEs for native software development (eg, writing Windows software on a Windows computer). However, this article will focus on IDEs for microcontroller firmware development. The MPLAB X IDE is a typical example. It allows you to create projects, edit and compile code, upload firmware to a target device and even run a debugging session to inspect the inner workings and memories of a project as it runs. MPLAB X IDE also offers features such as syntax highlighting, autocompletion and error checking. These sorts of tools require the IDE to be aware of the programming language and the structure of your project, but can be incredibly helpful in picking up errors early. MPLAB X is based on the NetBeans IDE, which was originally intended for the Java language. The following description may be easier to understand if you have had some previous experience with software IDEs and working with microcontrollers, and thus will be familiar with the terminology we will use. If you come across terms you’re not familiar with, you may want to look them up on the internet. VS Code Visual Studio Code (VS Code) is an IDE developed by Microsoft that was first released in 2015. VS Code can be used with a variety of languages and has the ability to install so-called extensions to expand its functionality. According to industry surveys, it has been ranked among the top development tools in recent years. We first noted VS Code in the March 2025 issue, when we introduced the Raspberry Pi Pico 2 microcontroller module (siliconchip.au/ Article/17796). This hardware release coincided with the porting of the C SDK (software development kit) for Raspberry Pi microcontrollers to the VS Code platform. In our review of the PICkit BASIC programmer and debugger (September 2025; siliconchip.au/Article/18849), we noted the release of the MPLAB Extension Pack for VS Code. This allows VS Code to be used as an IDE for project development for PIC microcontrollers and other Microchip Technology parts. That article also noted Fig.1: the splash screen for a recent version (6.30) of MPLAB X IDE hints at the rise of the MPLAB Extension for VS Code. Fig.2: VS Code’s Activity Bar allows quick access to features and extensions. VS Code Explorer Search Source Control Run and Debug Extensions MPLAB MPLAB AI Coding Extension 58 Silicon Chip Australia's electronics magazine siliconchip.com.au Fig.3: the MPLAB Extension Pack includes a few different elements (listed at left) to provide the features needed within an IDE. the inclusion of an AI coding assistant. Recent versions of the MPLAB X IDE seem to indicate (Fig.1) that VS Code will be the main IDE in the future. Of course, older versions of MPLAB X and even its MPLAB IDE predecessor are still available from the Microchip archive at siliconchip.au/link/abpn Like MPLAB X IDE, VS Code is available on multiple platforms, including Windows, Linux and macOS. VS Code can be installed on inexpensive Raspberry Pi computers (which are effectively Linux computers with ARM processors), but it does not appear to be officially supported on that platform. In this article, we will investigate the steps needed to install the MPLAB Extensions in the VS Code IDE to allow working with PIC microcontrollers and explore some features of VS Code. Then we’ll report on some other Microchip news, including new parts. Using VS Code We found that VS Code was easy enough to use, although it does several things very differently to MPLAB X, and there are some MPLAB X features that are still lacking. So it could be somewhat of a learning curve to make the change. We started by downloading it from https://code.visualstudio. com and installing it. siliconchip.com.au The Activity Bar at upper left is a good place to start exploring – Fig.2 shows the Activity Bar and the functions of its buttons. You may not see the lower buttons immediately, since they will be added when the MPLAB Extensions are installed. To install the MPLAB Extensions, click on the Extensions button and search for “MPLAB”. Then install the MPLAB Extension Pack, as seen in Fig.3. This includes several other bundled extensions that are needed. Note that VS Code supports both ‘light’ (black text on white background) and ‘dark’ modes; we have used a mix of screenshots to demonstrate this. Like the MPLAB X IDE, compilers are installed separately. We already had some compilers installed to work with MPLAB X IDE; we did not have to do anything for VS Code to detect and use these. If you need to install a compiler, we suggest installing the latest compilers from siliconchip.au/ link/acd7 For example, if you plan to work with 8-bit PIC microcontrollers (PIC12, PIC16, PIC18), you should install the XC8 compiler. For 32-bit parts like the PIC32 chips used in many Micromites, you should install the XC32 compiler. We also found that we did not need to install tool packs (for programmers) and device family packs (DFPs), which Australia's electronics magazine also appear to have been detected after being installed by the MPLAB X IDE. You may see a prompt at the bottom right corner of the VS Code window to install these or other software dependencies. VS Code also has a strong security focus. So you might also see prompts to ‘trust’ a folder. This should be fine for MPLAB projects, but be aware that VS Code can also work with code that can run on the host computer. So be cautious about trusting other projects, especially those that can run natively on your computer. Getting started Click on the MPLAB button on the Activity Bar and open the Welcome page from the Help → Welcome menu, if it is not already showing. That should show a button for Getting Started with MPLAB. Click on that and you should see a screen like Fig.5. This page is a good base from which to navigate until you become more familiar with VS Code. You can open an MPLAB X project if you have previously used MPLAB X to create one. Our firmware downloads for construction projects involving microcontrollers often include the MPLAB X projects and files, so you could download and experiment with one of those. November 2026  59 Fig.4: the Command Palette is a VS Code feature that provides access to search, as well as allowing commands to be entered as text. Fig.5 (below): the MPLAB Welcome Screen provides some useful starting points for PIC projects within VS Code. Fig.6: even at the start of a chat with the MPLAB AI Assistant, it is analysing the project files to provide insights into how to improve the code. MPLAB Extensions for VS Code uses a different project format, so changes made in VS Code are not reflected in the MPLAB X project properties, although changes to the source code are. We generally made copies of our projects so that the changes made by the two IDEs did not conflict. The Explorer (top button of the Activity Bar) should show the various files associated with the project. Most of the project properties are held in JSON files in a “.vscode” subfolder. JSON files are in text format and are generally human readable, so they 60 Silicon Chip can be edited if necessary. The Projects section of the MPLAB activity also shows the hierarchy of the JSON file and clicking on a field will open up a user-friendly view that resembles the Project Properties windows from the MPLAB X IDE. VS Code makes use of ‘Workspaces’, which generally include a project folder in their scope, although other folders can be added. The File menu contains options relating to Workspaces. You can drag-and-drop the buttons from the Activity Bar, as well as other sub-windows, and move items around to customise the work area. There are buttons to toggle the two sidebars and many more layout options under the View menu (Appearance and Editor Layout submenu items). Another interesting tool is the ‘Command Palette’, which looks like a search box at the centre top (by default) of the VS Code window. Fig.4 shows the drop-down that is seen when you click on the Command Palette. You can use the key combinations shown in Fig.4 to enter text into the Command Palette to search for a file, symbol or text or to run a command. It also shows handy defaults and recent Australia's electronics magazine actions. It’s a powerful way to access features when you are constantly using the keyboard while coding. Also see https://aka.ms/vscodekeybindings Using the MPLAB Extensions for VS Code is straightforward enough, and we found most of the problems we ran into were due to unfamiliarity with the layout and environment. We had no trouble compiling, using ‘>build’ in the Command Palette to perform a “MPLAB CMake: Build”. The MPLAB panel (selected from the Activity Bar) should show any connected programmers under the Tools dropdown. You can also use the Run menu to access programming and debugging options. MPLAB AI Coding Assistant To use the AI Assistant, you will require an API key, which in turn requires a free Microchip Technology account; this can be created at https:// login.microchip.com Once you have set up the account and logged in, you can copy the API key from www.microchip.com/ai-­ assistant/accesskey You will also need to have the Microchip Chatbot selected and using the MPLAB Agent. siliconchip.com.au Fig.7: the AI Assistant can also suggest code changes that can be accepted or rejected, as shown here. Note how we have asked it to keep, but comment out, the old code for reference. This view shows dark mode (white text on black). Opening the AI chat window from the Activity Bar should prompt for the API key if it is needed. The interface is much the same as other AI chatbots, where you type in a question or prompt and the AI agent processes the query and responds. Sometimes it will pause and ask for permission to review an online resource. Context is important, so we started our chat (Fig.6) with a brief statement about the relevant facts that related to our project and asked for a review. The analysis stretched for a few pages beyond what is shown here. It included several correct observations and some suggestions of what to work on. Fig.7 shows the end result of two further prompts. The first prompt was a request to modify a function to change the Peripheral Module Disable (PMD) registers so that only the IOC (interrupt on change) peripheral is enabled; this is done to minimise siliconchip.com.au power consumption in sleep mode while allowing sleep to be ended by a pin change interrupt. The AI Assistant made an appropriate suggestion, and the editing window provides the option to reject or accept the change in place. Instead of accepting, we asked it to comment out the old code instead of replacing it; the result is shown in Fig.7 and accepted as looking correct to us. We were similarly able to generate startup code to switch off the PMD registers. The AI Assistant was asked to scan the code for peripheral usage and suggest appropriate values to enable only the peripherals that are used by the code. Its assessment of the necessary peripherals was quite good, although it did take a bit of troubleshooting to get the exact values needed. In this case, the AI Assistant was helpful in suggesting troubleshooting strategies such as disabling each peripheral, one Australia's electronics magazine at a time, to try to identify the problematic case. We found that the AI Assistant was quite helpful in avoiding the tunnel vision that can sometimes occur during troubleshooting and could suggest alternatives to those that had been considered. It’s almost like having someone else to share the problem with. Sometimes the responses are quite long-winded! There is the constant proviso that AI can make mistakes; sometimes, its apparent verbosity can appear overconfident. At one point, it asked, “Let me know if you want this change directly committed to your project, or have further optimization questions!” We wish we had that sort of enthusiasm! We think that these applications are where the AI Assistant will be useful. Attempting to manually generate the necessary commands from the register bit fields in the datasheet can be tedious and error-prone, while the November 2026  61 AI Assistant can streamline it. It also seems handy at generating things like bulky or repetitive code. The code that was generated appeared to be well-formatted with detailed comments, so could be used to improve code readability. The AI Assistant was also helpful when we had questions about the VS Code environment and could even access data sheets and project configuration files to respond to queries. Other notes Just like MPLAB X IDE, there is an MCC (MPLAB Code Configurator) extension for VS Code. We don’t use MCC much for our projects since we have specific library files and drivers that we use, so we did not have much need to test it out. We could not easily find a way to install and check tool (programmer) packs and DFPs (device family packs). These are the software profiles that are necessary to work with specific programmers (such as PICkits) or microcontroller families. It appears that the DFPs are automatically installed if needed when a new project is created. Quite a bit of automatic downloading occurred, so we could not easily see how much storage space various features required. Otherwise, packs that are installed through the MPLAB X IDE are automatically detected in VS Code. We observed that some of the extensions have notes that “Features and functionality will remain in active development”, so it appears that the MPLAB Extensions environment is still not complete, at least compared to MPLAB X IDE. We also could not find (within MPLAB Extensions for VS Code) a tool for setting up configuration fuses or viewing memory contents, except for individual variable watches in a debugging session. These aren’t things that we need often, but are invaluable when they are available. XC8 compiler 4.00 While we were writing this article, we saw that version 4.00 of the XC8 Compiler had been released. The notes for XC8 also mention improvements relating to debugging support for assembly code and improved tools and diagnostics. The changelog doesn’t indicate any fundamental changes, but the note that XC8 has now “Removed license restrictions for optimization features” is quite an understatement! Why do we use so many PICs? You may be wondering why we use so many PICs in our projects. Why not an Atmel AVR chip, an STM32 from ST Micro, an NXP microcontroller, or something else? We do sometimes publish projects using those other chips and many of them work well enough. While Microchip Technology advertises in the magazine, that isn’t contingent on us using their devices. The reason is partly historical. We’ve used PICs for decades and have lots of experience with them. However, it’s mainly because we like working with them. A given PIC may not be the fastest chip or the best in every way, but there are a few things they do consistently well. They’re often inexpensive, with more flash and RAM than similarly priced competing chips. That means we don’t have to stress so much about making our program fit. They’re also pretty easy to program once you have the hardware, which will work with just about any PIC. Jumping from an 8-bit PIC to a 16-bit or 32-bit device takes very little effort. Plus, Microchip offers a wide range of devices, from tiny and cheap to big and powerful. We also find that the some aspects of PIC programming (such as the configuration bits) are simple and elegant. We are currently producing an article comparing 8-bit PIC and AVR parts and their configuration bits, which are handled quite differently. Importantly, we only need a small range of hardware to make the pre-programmed microcontrollers we sell in our Online Shop. PICs also tend to have excellent peripherals, many of which can be mapped to different pins. That includes things like PWM, hardware serial, good ADCs, DACs, comparators, programmable logic blocks and more. Other micros have those things too, but some we’ve tried had pretty sparse peripherals, limiting what we could do. In addition to PICs, we have also used Raspberry Pi Picos in a few projects as they have some great features too. We have also been impressed with some of the features of the STM32 chips Andrew Levido has used in his projects; we could imagine using those one day as well. 62 Silicon Chip Australia's electronics magazine This effectively means that the previously PRO level optimisations (which could only be accessed with a paid licence) are now free to all users. This applies to all XC compilers and now makes the -O3 (optimise favouring speed) and -Os (optimise favouring size) options for the XC8 compiler available at no cost. Most of our projects have deliberately avoided the PRO level optimisations so that our readers do not need to pay for a licence to compile our code, although there have been a handful of cases where this has been necessary. Fig.8 shows the Compiler section of the Project Properties under VS Code. While the higher (“3” and “s”) optimisations are available for selection in earlier versions, they will fail on older compiler versions, since these still implement the licence checks that have been removed from XC8 version 4.00. New chips It has been a while since we last reviewed a new family of Microchip microcontrollers. We investigated the PIC16F181xx family of parts (along with some others) in October 2022 (siliconchip.au/Article/15505). Since then, we have used the 20-pin PIC16F18146 in many projects. For projects where smaller chips have been required, we have also used the 14-pin PIC16F18126 and the 8-pin PIC16F18115. These have many handy analog features, including an 8-bit DAC (digital-to-analog converter) and a 12-bit ADC (analog-to-digital converter), as well as many digital peripherals. We noticed the introduction of the PIC16F131xx family of parts a few years ago but did not have the opportunity to do much with them at the time. This family of chips includes a CLB (configurable logic block) peripheral. The PIC16F132xx family has just been released, and it too includes the CLB peripheral. CLB Previously, we have used the CLC (configurable logic cell) peripheral that is featured in the PIC16F181xx family. The CLC can be used to set up logic that can operate independently of the core processor. The CLC could be considered equivalent to adding one or two simple logic ICs, such as logic gates or perhaps a latch, to a microcontroller. siliconchip.com.au For example, it can be used to mix the outputs of two peripherals to generate signals that cannot be directly created by existing peripherals. Nicholas Vinen’s RGB LED Star from December 2025 (siliconchip.au/ Article/19372) used the CLC to create waveforms to control WS2812-based LEDs. This combined a PWM signal with an SPI signal to suit the specific timing needed for these chips. The CLB has some similarities in that it can be used to combine peripherals via logic to work with unusual signals. However, it is much more advanced and is more like a CPLD (complex programmable logic device) than a simple logic chip. So it can emulate much more complex logic. The CLB is based on a unit known as a BLE (basic logic element), seen in Fig.9. There are 32 BLEs available in all PIC16F131xx and PIC16F132xx parts. Each BLE incorporates a four-­ input LUT (look-up table) to provide combinatorial logic, plus a latch to allow sequential logic, such as shift registers. Building blocks like these BLEs are common to many programmable logic devices, including FPGAs (field-­ programmable gate arrays). There are some project examples using the CLB at https://mplab-discover.microchip. com/v2?dsl=clb Unlike other peripherals, the CLB requires a substantial amount of data to be initialised. Each of the 32 LUTs requires 16 bits of data to determine the LUT output for each of the 16 combinations of four bits at its input. There are also bits that determine where the inputs and outputs are routed so that complex logic can be developed from connecting multiple BLEs. Many peripherals might have a handful of byte-sized registers to set up, while the complexity of the CLB requires its registers to be supplemented by an entirely different system. Complex programmable devices store their data in a so-called bitstream, and it is the way this bitstream is loaded that is unusual. The PIC16F13xxx (PIC16F131xx and PIC16F132xx) parts also include a CRC (cyclic redundancy check) memory scanner that can scan through the non-volatile flash memory and confirm (using a CRC code) that the memory has not been modified or corrupted. The CRC peripheral has an alternative mode that can scan a part of flash siliconchip.com.au Fig.8: recent versions of the XC compilers allow use of the “3” (-O3) and “s” (-Os) options that were previously restricted to paid PRO licence holders. Fig.9: the CLB peripheral on the PIC16F132xx family contains 32 of the BLE blocks seen here. The LUT can be used to make combinational logic (including AND, OR, NOT, XOR gates), while the latch can be used for sequential logic, such as memory and shift registers. memory and transfer the contents to the hidden registers that configure the bitstream of the CLB. So this step is used to load the bitstream from non-volatile flash memory into the working memory of the CLB. In a typical application, the on-chip firmware would perform a bitstream load sequence and set up any I/O pins or internal peripherals to connect to the CLB. Finally, the processor would activate the CLB peripheral so that it is active. The PIC16F132xx parts also have the ability to load the bitstream at startup and then halt the processor, effectively becoming a pure logic device. Generating the bitstream There are some handy tools available to turn a conceptual design into a functional bitstream, including a user Australia's electronics magazine interface that can be used to lay out logic elements in a graphical fashion and then synthesise a design into a bitstream. The tool can be found at https:// logic.microchip.com/clbsynthesizer Fig.10 shows the tool editing a 12-bit linear feedback shift register (LFSR), which can be used to generate pseudo-­ random values. It has no inputs and the eight most significant bits are available as outputs. The OR gates are necessary to trap the all-zeroes state that might otherwise cause the LFSR to latch up. The outputs can be mapped to different pins via the PPS (peripheral pin selection) module. The synthesis tool requires internet access, since Microchip’s servers host the software that is needed. Internally, the tool uses the Verilog HDL (hardware description language) and modules can be created with snippets of Verilog. The open-source Yosys November 2026  63 Fig.10: you can try out the CLB Synthesiser tool on the Microchip website, even if you don’t have an IDE installed. The design shown here implements a 12-bit LFSR (linear feedback shift register) that can generate pseudo-random data. framework is used for digital logic synthesis. The bitstream download also includes other synthesis files and some C code to initialise the CLB. There have been some efforts to analyse and provide alternative means to generate the bitstream. You can see one project at https://mcp-clb.markomo.me Other features This family also includes a 10-bit DAC. We’ve found the 8-bit DAC on the PIC16F181xx family quite handy, so we may investigate this family further for future use. The CLB feature is also available on PIC16F131xx parts, as we noted earlier. The first members of the PIC16F132xx family were the larger (28-, 40- and 44-pin) chips, which may be useful in the case of projects that require microcontrollers with more I/O pins. We have recently seen the announcement of 8-pin, 14-pin and 20-pin parts in this family. The PIC18-Q35 family also includes CLB peripherals. PIC18 parts have an 8-bit processor, like the PIC16 parts, but are generally more powerful. Interestingly, the CLB in these parts has 128 BLEs, so they can implement even more complex logic. The CLB is certainly a fascinating peripheral, and we can see that it has a lot of potential. The larger parts may 64 Silicon Chip be handy if we need more I/O pins for a project. Concepts like LED and switch matrix scanning with many I/O pins are likely to be well-suited to handling by CLB logic. So far, we have not found a compelling project use for the CLB peripheral. With the recent release of 20-pin parts in this family, we may see the likes of the PIC16F13246 as a drop-in successor to the PIC16F18146 that we have used so often. PDID PDID stands for Programming and Debugging Interface Disable. As the name suggests, it can be used to lock down the programming interface, preventing programming, debugging and erasure of the chip. This feature is present on the PIC16F132xx family of microcontrollers and is set by the ICSPDIS configuration bit. Crucially, once the ICSPDIS bit has been enabled, it cannot be disabled and the device cannot be reprogrammed by an external programmer or debugging tool. It is clearly intended to be a security measure to prevent firmware tampering. Of course, this feature should be treated with absolute care, since it cannot be disabled. Interestingly, these parts still allow other methods for modifying their flash memory, so it is possible to allow Australia's electronics magazine firmware updates. The internal NVM (non-volatile memory) controller can write to flash memory, and thus the firmware can implement a bootloader to allow updates. But that can only occur if the firmware has been written to allow this. Conclusion With the Raspberry Pi Pico Extension for VS Code being the official way to use the Pico C SDK, we expect that we will be using VS Code more as time goes on. The MPLAB Extension for VS Code IDE looks to be very useful, although it appears that some features present in MPLAB X IDE are not yet available in VS Code. For now, we will use both the MPLAB X IDE and VS Code for PIC programming. Having both installed will also streamline the addition of tool packs and device family packs. One thing we like about the VS Code IDE for Microchip devices is that it’s quite a bit faster than MPLAB X IDE as it does not rely on Java. We found the AI Assistant to be helpful in many cases. It even has the ability to make changes directly to code, so it would be entirely possible to write the bulk of a project through AI prompts only. Like many AI implementations, the AI Assistant is not perfect and can make mistakes, so it is a tool that SC should be used with care. siliconchip.com.au DCC Model Railway Kits DCC is a great way to control model trains, and we have a series of projects that can be used in a model train layout from a DCC Decoder to a Destination Display (siliconchip.au/Series/455). DCC Base Station SC7539 Kit ($90 + P&P) – includes all parts except the case, power supply and optional headers DCC Remote Controller SC7552 Kit ($35 + P&P) – includes all parts except the case and cabling DCC Accessory Decoders Snap-type Kit (SC7685, $40 + P&P) Servo-type Kit (SC7686, $40 + P&P) I2C Controller SC7690 Kit ($30 + P&P) – for DCC Accessory Decoders DCC Booster and Reverse Loop Controller Kit (SC7579, $45 + P&P) – includes all parts, except the case, OLED screen, power supply and front panel Stepper Motor Driver SC7601 Kit ($30 + P&P) DCC Decoder SC7524 Kit ($25 + P&P) Destination Display SC7697 ($22.50 + P&P) – does not include the screen (available separately) siliconchip.com.au microDCC Decoder SC7617 Kit ($25 + P&P) – choice of a bell or whistle sound for the software Australia's electronics magazine November 2026  65 Ideal Bridge Rectifier Project by Phil Prosser Background image source: https://unsplash.com/photos/a-bunch-of-speakers-that-are-sitting-on-a-table-YlSfH5XDAto for Power Amplifiers If you are making a dual-rail power supply and need high efficiency and/or low dissipation, a conventional bridge rectifier has distinct limitations. Audio power amplifiers and dual-rail power supplies are good examples of where this circuit can provide significant benefits. S emiconductor diode rectifiers have been the default choice for converting AC to DC since the 1960s. They are inexpensive, robust and relatively efficient, at least compared to what came before them (diode valves, selenium rectifiers and such). However, these days you can do a lot better. A rectifier using active devices can be much more efficient, meaning you get a higher voltage output with less power wasted as heat. That also means you don’t have to worry so much about getting the heat out of the device. We previously presented an ideal diode bridge based on the Linear Technology (now Analog Devices) LT4320 IC in December 2023 (siliconchip.au/ Article/16043). A little later, in the September 2024 issue, we published a discrete version, which sought to avoid the high cost of that IC and had some other advantages (siliconchip. au/Article/16580). The LT4320 chip controls four N-channel Mosfets, which allows for a high load current, but the maximum voltage you can rectify is limited. Also, it won’t work with a centre-tapped transformer, so if you want to generate split (positive and negative) rails, you need two of these relatively expensive devices. 66 Silicon Chip The discrete version used P-channel Mosfets on the high side to simplify the design. While not limiting the maximum voltage, such devices with high voltage and current ratings, plus the low on-resistances required for good performance, are scarce and expensive. One application where people sought to use these circuits was in the power supply of high-power audio amplifiers (eg, 200W+). The LT4320 design could be used, but as mentioned above, it would demand the use of two stacked LT4320-based rectifiers. » Low-loss rectification of centretapped transformer secondaries to produce split rails » Low voltage loss and low dissipation compared to a standard diode rectifier bridge » Four board versions: SMD with TO-252 (D2PAK) or TO-220 Mosfets; through-hole with TO-220 or TO-247 Mosfets » From 5-0-5V AC in (~±7V DC out) to 50-0-50V AC in (~±72V DC out) » Load currents up to 20A continuous, 100A+ inrush » Handles transformers up to 500VA » Works with large filter capacitor banks The later Discrete Ideal Bridge Rectifier we published has no such limitation, but to increase the voltage rating would require horribly expensive (if available) Mosfets, which made that an unattractive approach. This project gives you the best of both worlds as it can handle high voltages and a split supply without needing an expensive IC or P-channel Mosfets. Other applications where an ideal bridge rectifier comes into its own are in DC supplies where high continuous currents are drawn. In our Dual Hybrid Power Supply (February & March 2022; siliconchip.au/ Series/377) with a 5A continuous load, the bridge was dissipating about 10W, which demanded that the bridge be mounted to the heatsink. An Ideal Bridge Rectifier brings this dissipation down to just a couple of watts at most. A third application is where you are seeking to efficiently harvest energy, for example, from a wind turbine or a generator. In that case, you want to avoid the loss of the forward diode drop. The principal elements of this circuit are applicable in that use case too. To show the difference between a conventional bridge and our Ideal Bridge rectifier, compare Scope 1 & Australia's electronics magazine siliconchip.com.au Features & specifications Scope 1: rectification with a standard 40A diode bridge into Scope 2: the same setup as Scope 1 but with our Ideal a 120W load. The ground reference is the positive output rail Bridge Rectifier. The gate drive (mauve) goes 4.5V above the (blue), so the AC input (yellow) shows the voltage relative to rail, which in this case is sufficient to switch on the Mosfet. this and thus the diode voltage drop. Nearly 1V is dropped There is an 80mV offset of the AC input above the DC rail, across this large bridge even at modest loads. which gives safe switching of the Mosfet. The initial ‘glitch’ is the delay in the Mosfets being switched on – this test signal was running at 200Hz. Scope 2. These show a 10V RMS sinewave being rectified, first using a conventional 40A diode bridge, and then the Ideal Bridge. Design considerations Since the request was for an Ideal Rectifier that can be used in an audio power amplifier, let’s look at some reasonable requirements for such a power supply. The requirements can vary, so we had to consider the average case: • A typical amplifier can deliver about 200W into 8W; this sets the maximum voltages • The amplifier should be able to drive a 4W load with the maximum rail voltages; this sets the current ratings • A single board should handle the full split supply • The bridge should present much less than the 1.1V+ per ‘diode’ that you will see across a conventional bridge, consequently having lower power dissipation • We should keep the parts cost reasonable The derived requirements from the above are: • Rectified DC rails of ±60V DC, which can deliver an amplifier output of around 40V RMS. • A continuous output current of 10A for a 4W load, which we should assume is doubled if used in a stereo setup, so 20A. Normal audio has a very substantial crest factor, so while peak currents may be 10A for a 4W load, in reality the average current will be very much less siliconchip.com.au than this. Even in a subwoofer channel for a serious party, it would be surprising to see 10A continuous unless you have very heavy-duty speakers. In a practical application, this would correspond to a 40+40V AC transformer of 500VA or more, with its output rectified to feed some large (say, 20,000μF per rail) filter capacitors. One thing we need to consider is worst-case voltages. Mains voltage variation and transformer regulation can be significant. The nominal mains voltage range is 230V AC +10%, -6%, meaning a range of 216-253V AC. However, I have seen mine go well beyond this with the current trend towards many solar installations. Transformer regulation is typically 6%. This says our output supply will be at maximum: (40V AC + 10% + 6%) × Fig.1: the ideal bridge concept. It comprises four N-channel Mosfets with their gates driven by a control circuit. √2 +10% = 72V, giving us our ‘absolute maximum’ rating. The ‘nominal operating’ voltage level will be about 56V. The extra 10% at the end is a safety factor we are adding. In a conventional dual-rail power supply, the rectifier component, normally a diode but in our case a Mosfet, sees the total voltage between the positive and negative rails, so in our case it will have to handle an absolute maximum of 144V with the maximum mains supply and minimum load, plus a 10% safety margin. Our Mosfets therefore need the following ratings: • Vds > 150V • IDcont >> 50A (the peak current will be over 100A at switch-on) • Rds(on) < 10mW (trying to be reasonable) If we look for suitable P-channel Mosfets at Mouser, we see no options at all. If we allow a higher Rds(on) figure, the cheapest option is $27 for a single Mosfet. Ouch. Looking at an N-channel option, we have options starting at $4 in single quantities and $2-3 each in lots of 10. Of the 22 through-hole options available today, there are multiple usable options under $5 each. So all we need to do now is make our circuit drive four N-channel Mosfets in a bridge configuration, as shown in Fig.1. To switch on those N-channel Mosfets requires us to drive their gates (G) to a voltage above their sources (S) by about 10V (that’s enough to fully switch on the majority of Mosfets we are likely to use). Australia's electronics magazine November 2026  67 We don’t have a convenient supply rail above the output voltage, so like many Mosfet-based circuits, we will need to ‘bootstrap’ our gate drive for the upper two Mosfets, charging a capacitor during the negative half-­ cycle swing of each AC input waveform. We don’t have to do that for the lower Mosfets since we can simply pull their gates up to the 0V rail or the positive rail, as long as we clamp the voltages to something reasonable. Exceeding the Vgs rating of the Mosfet will damage it; this is typically in the range of ±10V to ±30V. A zener diode clamp will solve that easily. The majority of ideal bridge controllers are designed to rectify a single AC input to produce a DC output. Since their design is optimised for this, many of the integrated-circuit controllers switch the lower Mosfet on based on the associated AC input being at a lower voltage than the other. That means the lower Mosfets are switched on alternately with a ~50% duty cycle. This works just fine in a single-rail application, but precludes their use in a dual-rail application, where the Mosfets need to be on only when the input voltage is high enough to charge the filter capacitors. The LT4320 switching is shown in Fig.2 (from LT4320 data sheet). The green and orange dotted lines show the lower Mosfets being on for the majority of each half-cycle. What we need is the Mosfets switched on only during positive and negative excursions, like we see in Scope 3 & Scope 4, which show our prototype in operation. Our circuit to do this is shown in Fig.3. This has a fair resemblance to the simpler circuit for the Discrete Ideal Bridge Rectifier from September 2024, but exchanges the ‘pull-down’ on the top side Mosfets to a bootstrapped ‘pull-up’ that can drive the upper Mosfet gates to more than 10V above their sources. This lets us swap the upper P-channel Mosfets of the old design for N-channel types. Circuit details The two upper halves of the circuit are effectively identical (shown as mirror images). Similarly, the two lower sections are mirror images of each other, but they’re simpler because they don’t need to generate the higher-­ voltage bootstrapped supply for driving the Mosfet gates. Four named sections of the upperleft quadrant are shown in coloured, dashed boxes, so we will explain the operation of these sub-circuits. Current sink #2 sinks about 0.6mA to the negative output rail. This is required for the input comparator, which is formed from PNP transistors Q4 and Q6. With the maximum rails totalling 150V, the 0.6mA current sink will result in about 0.1W dissipation in Q9. Q4 and Q6 compare the AC1 input voltage to the positive output. Diode D6 is required to protect Q4 when the AC1 input swings negative. D3 is there to ensure we have matched voltage drops so that the comparator operates correctly. These diodes are BAV21 types as they need to have a minimum voltage rating of 150V and be reasonably fast, at least on the scale of the mains input. These diodes also need to be Scope 3: the switching waveforms for the positive rail at 11.5A RMS. A very minor switch-on waveform for the negative rail Mosfet is seen, but it has no effect. At this current, after several minutes, the Mosfets reached about 60°C. 68 Silicon Chip reasonably well-matched and at the same temperature, as the voltage drop across these directly affects our comparator function. We have placed these next to each other on the PCB, as we have with the comparator transistors, for thermal matching. The 220W resistor introduces a small offset voltage on the AC1 input side, which ensures that the AC input voltage must exceed the DC output voltage before the comparator output changes. The comparator operates by the bases of Q4 & Q6 being connected, and the emitters connected to the AC1 and DC output voltages via diodes. The comparator has a very high differential input voltage range due to the presence of D6 and D3, which stop the Q4 & Q6 base-emitter junctions from breaking down, to accommodate the full AC input voltage range. Current sink #1, which pulls current through Q4, is actually a current mirror of current sink #2. This will pull 0.6mA through D17. When the AC1 input is lower than the positive DC output, Q4 will be switched off, and this current will flow through ZD1 and D1. This will charge the 100nF capacitor to 12V, the breakdown voltage of zener diode ZD1. While the AC1 input is lower than the DC output, Mosfet Q1’s gate is pulled low by the current sink, which has plenty of time to charge the 100nF capacitor to 12V between AC cycles. As soon as the AC1 input voltage exceeds the DC output voltage, the potential of the emitter of Q4 goes above the emitter of Q6 and Q4 starts conducting. As Q4 switches on, it Scope 4: the switching waveforms for the negative rail at 11.7A RMS. It’s similar to the positive waveform; we see the positive Mosfet only on briefly, and a heavy drive to the negative Mosfet. This plot only shows one AC input to the bridge, but you can see DC ripple from the second AC input. Australia's electronics magazine siliconchip.com.au Fig.2 (left): the gate switching waveforms for the LT4320 IC show the gate drive for the lower Mosfets in dotted green and orange. These are on for much of the waveform, so if this device were used in a dual-rail application, it would short the transformer secondaries to the capacitors for the full negative cycle. Fig.3 (below): the Ideal Bridge Rectifier circuit. This will only work properly with dual/tapped secondary windings, producing positive and negative rail outputs into capacitive filters. This is ideal for power supplies in power amplifiers and some bench supplies. Note that the circuit shown here applies to the through-hole version. The SMD version uses equivalent components, but lacks the fused connections. siliconchip.com.au November 2026  69 supplies current through D8 and D17, pulling the collector of Q8 (current sink #1) high through D17. At the same time, it pulls the low side of the capacitor high through D8. The high side of the capacitor thus goes 12V above the positive output, which is connected to Q1’s gate, so Q1 switches on. If the Mosfet is switched on hard enough to bring the AC1 input within the offset voltage of the DC output (set by the 220W resistor), the comparator will reduce the drive to the Mosfet gate. So the circuit operates in a linear regime, switching on the Mosfet hard enough to reduce the 0.6V body diode drop to a few tens of millivolts. If you look at the gate drive waveforms in the scope waveforms, you will see some wiggles in the gate drive voltage at the leading edge of each pulse. This is the circuit operating in the linear region; only on the flat top of the waveform is the Mosfet switched on hard. D17 is present so that on deep negative swings of AC1 to a minimum, ZD1 and the 100nF capacitor can be pulled below the negative rail and therefore do not switch on Q1. If D17 was not present, as the AC waveform went negative, the negative end of the 100nF capacitor would break down the collector base/emitter junction of Q8. This would switch Q1 on, which would be bad. Once the AC input goes below the DC output, the Mosfet switches off, since current sink #1 pulls the Mosfet gate low via the zener diode and capacitor. The 100kW resistor in the gate drive section ensures that the Mosfet gate is always discharged when power is first applied. As you can see, the core elements of this design are pretty simple, but those diodes are there to deal with a number of subtle challenges. The Mosfet can be any suitably rated N-channel device in a TO-220 package. 100nF capacitors are sufficient for the gate drive reservoir, even for very large Mosfets. Choose Mosfets with Vgs(th) threshold voltage of 4V or more, as our negative gate drive ‘low’ is about 1.2V, and we don’t want any chance of the low-side Mosfets being partly on when they should be off. Most Mosfets use a standard pinout. Very substantial N-channel parts can be had at a good price. The IPP075N15N3GXKSA1 costs $32.30 for 10 and has an Rds(on) of just 6.2mW. resistor, and assuming an hfe of 30 for those two transistors, that happens at around 8V [(2 × 1.2mA ÷ 30) × 100kW] or about ±4V at the output (closer to ±5V when you take into account the base-emitter voltages). So 100kW is a good value for lower voltages, but with a ±75V output there will be nearly 150V across that resistor, so it will dissipate 225mW (150V2 ÷ 100kW), which is a bit too close to the ¼W resistor ratings for comfort. So bumping it up to a higher value like 220kW at the upper end of the supply voltage range is a good idea. How warm will the current source transistors, like Q15, get? With a ±75V output, Q15’s dissipation is around 150mW, which is easy for an SOT-223 package device to handle. Design notes & modifications There are four PCB designs. Two use through-hole parts and are basically identical except that one is for TO-220 package Mosfets and the other is for TO-247 package Mosfets. The advantage of TO-247 is that the packages are larger, so they can usually handle higher current and dissipation, but there are fewer TO-247 Mosfet options compared to the ubiquitous TO-220 parts. The third design uses mostly SMD parts, with some exceptions, such as the zener diodes. The Mosfets are in D2PAK (TO-252), a very common package for SMD power Mosfets, similar to TO-220 but designed for horizontal surface-mounting. There is also an SMD + TO-220 Mosfet board option. The SMD board is somewhat smaller, at 66.5 × 68mm compared to The current sources operate between the positive and negative rails. This allows the entire circuit to operate without a ground connection. However, it forces the current source to use a pull-up between the rails. The negative current source operates at a higher current than the positive one and presents the greatest challenge thermally. The 100kW resistors on the low side should be increased to 220kW for output rails above ±40V. We can’t make the value too high as it affects the minimum voltage at which the circuit will operate. There needs to be enough current through this resistor to switch Q14 and Q15 on sufficiently to deliver about 1.2mA of collector current each. With a 100kW Versions This is the SMD version of the Ideal Bridge Rectifier, using IRFS4115 N-channel Mosfets in a D2PAK (TO-252) package. 70 Silicon Chip Australia's electronics magazine siliconchip.com.au Scope 5: this plot has the oscilloscope ground connected to Scope 6: this plot has the oscilloscope ground on the the negative rail, allowing us to see the AC waveforms in positive rail; we can again see the gate drive in yellow, well purple and blue relative to this, and the gate drive in yellow. over 10V. The AC inputs in mauve and blue show that the Channel 2 (cyan) is the voltage at the load, after 60cm of AC input rises 300mV above the positive DC output. This heavy duty hookup wire. We see a full 12V gate drive here. means we have 300mV across the Mosfet, consistent with the 12.1mW Rds(on) figure for the Mosfet we used here. 76 × 82mm for both of the throughhole versions. It lacks just one thing: onboard fuses (and the corresponding connectors). You can use inline fuses, or run it without fuses; after all, a standard diode bridge doesn’t include any fuses. Instead, they are usually in the mains input and on the amplifier boards being driven. The fourth design also primarily uses SMDs, similar to the above version, except it allows through-hole TO-220 Mosfets to be used if that is desired (eg, if you can get better/ cheaper TO-220 package Mosfets or you want to add flag heatsinks). While it is identical to the TO-252 version apart from the Mosfets, some SMD components were moved to make room for them. Depending on your application, you may be able to use cheaper parts than we are suggesting. If your total rail voltage will never exceed 100V, you can use 1N4148 diodes rather than the BAV21 devices, and you could choose lower-rated Mosfets. For example, 100V-rated Mosfets with similar Rds(on) and current ratings can be found for less than $2 each. Be judicious in these choices, but there are real savings to be had depending on your use case. residue and apply a conformal coating such as Chemtools CT-ACC-400, available from Altronics. That’s especially recommended if you are going to be pushing the device to the upper end of its 150V maximum total voltage rating. Testing the prototype To properly test the Ideal Bridge Rectifier prototype, we took a 600VA, 45V + 45V AC transformer, two 33,000μF computer-grade capacitors (which are simply enormous) and ran this combination into an 8W resistive load, which is way beyond what you would see in an amplifier. We stopped when our load hit 300°C. We omitted a soft-start circuit in our tests, which you should never do with this sort of power supply. We do not recommend you do what we did, as a slip could lead to very hazardous faults. Construction First, make sure you have the right board to suit your parts: code 18109261 (76 × 82mm) for the throughhole version with TO-220 Mosfets, 18109262 (76 × 82mm) for the version Photo 1: measuring the Mosfet temperatures during operation with a 20A+ continuous load. I used a non-contact IR thermometer as it isn’t safe to put fingers near the board when powered or while the capacitors may still be charged! Safety We have followed IPC guidelines on track separation for benign environments and non-coated boards up to 150V in the PCB layout. In normal use, this will be fine. However, we recommend that once you have verified the board is working, you clean off the flux siliconchip.com.au We learned a few things from these tests. The omission of the soft-starter resulted in the mains circuit breaker tripping about one in four times we switched this on. The results are shown in Scope 5 and Scope 6. That was using the D2PAK (SMD) version of this circuit because these devices have much less thermal dissipation capacity than the through-hole devices in the way we have applied them. So it was a worstcase test. Throughout these tests, the Mosfets were dissipating about 600mW, and after about 10 minutes, they were at 45°C, as shown in Photo 1. Australia's electronics magazine November 2026  71 with larger TO-247 Mosfets, 18109263 (66.5 × 68mm) for the SMD version with TO-252 Mosfets or 18109264 (66.5 × 68mm) for the SMD version with TO-220 Mosfets. Refer to Figs.4-7 as a guide during construction. Start by mounting all the resistors. For lower-voltage applications, use 100kW resistors as marked with an asterisk on the PCBs (or in red in Figs.47). For higher-voltage applications, substitute 220kW resistors for those. Follow with all the diodes. Pay attention to their orientation. I normally endeavour to keep these all facing the same direction, but to keep the board size small, we need to optimise routing and thus component orientation. Follow with the remainder of the transistors. Note that the positive rail comparator uses MMBTA92/MPSA92 transistors, as Q5 can experience the full rail voltage (base-collector) on negative AC swings. Q9 is the same part as Q5, because we need the Vbe on Q5 and Q9 matched for the comparator to work. Do not mix these up with the BC series parts and be aware that the pinouts between the through-hole BC- and MPSA- prefix parts are reversed. On the through-hole version, we want to glue the comparator transistors together in pairs. This is about as good as we can do to ensure they remain at the same temperature. Take two pairs of the BC546 and two pairs of the MPSA42 and glue them faceto-face using super glue or shrink a length of heatshrink tubing around them. Put them straight into the PCB so you are sure they have gone into the right spot. The MJE340/350 and equivalent PZTA-prefix SMDs ensure we have good power dissipation headroom. Watch the orientation of the throughhole parts. We have marked the heatsink tab sides of these on the board and indicated the base pin so that you can check if you are in doubt. Finally, mount the capacitors, fuse clips and spade connectors. Solder the fuse clips and connectors on both sides. When you mount the Mosfets, make sure these are well soldered to both the top and bottom layers. If you expect to be drawing in excess of 10A continuously from the power supply, you might want to think about heatsinking the Mosfets with modest flag heatsinks. Be aware that the tab of these is connected to the drain pin, so these present an electric shock hazard. Thus, the Figs.4-7: use these PCB overlay diagrams as a guide during construction. Make sure you use the one that matches the board you have (note the codes, ending in 1-4). The board with TO252 Mosfets has two of them installed on the underside. Those are the only parts that mount on the bottom (it simplifies routing and helps spread out the heat load). 72 Silicon Chip Australia's electronics magazine siliconchip.com.au heatsink definitely needs to be insulated from them. Parts List – Ideal Bridge for Power Amplifiers Testing Through-hole version Setting the Ideal Bridge Rectifier to work should be undertaken at low power, to ensure things are working properly before you connect this to a large transformer and capacitor bank. We used a signal generator and 100μF filter capacitors with 1kW loads to test ours, as shown in Fig.8. We want to make sure the rectifier works before we connect it to a massive transformer and capacitor bank. The rectifier itself presents very little load to the supply, so you can use a “supply” as modest as an oscillator for testing. 1. Connect your oscilloscope’s ground to the ground point. 2. Set the oscillator to produce a sinewave at 50-200Hz and its maximum undistorted voltage. Make sure it is delivering more than 10V peak-topeak; if it can’t, you need to amplify it with a small audio amplifier. As an alternative to this, you could use a small AC plugpack with, say, a 100W 5W resistor in series with the output. 3. Connect the oscillator to the AC1 input of the Ideal Rectifier board and: a. Check with your oscilloscope that the oscillator has not been loaded down too much. b. Check the positive and negative outputs and see if you can measure a credible rectified DC voltage (notionally 1.4 times the RMS AC input). c. You should see ripple as the capacitors discharge on each half-cycle. d. Check the voltage on the cathode of zener diodes ZD1 and ZD4. ZD1 should have a waveform as shown in Scope 7, while ZD4 should have a waveform as shown in Scope 8. 4. Swap the oscillator to the AC2 input and repeat the above tests, looking at the cathodes of zener diodes ZD2 and ZD3. 5. If anything looks wrong: a. Check the diode orientations. There are quite a few, and they all need to be right. b. Check that your transistors are in the right spots, especially that the MPSA92 and BC5xx devices are where they need to be. c. Check that the TO-126/TO-225 package medium-power devices are the right way around 1 double-sided PCB coded 18109261, 76 × 82mm 6 5mm pitch PCB-mount 6.3mm vertical spade connectors (CON1-CON6) 4 M205 PCB-mount fuse clips (F1, F2) 2 M205 fuses (F1, F2; ratings to match application – 10A slow-blow suggested) 1 can of conformal coating spray (optional) [Chemtools CT-ACC-400, Altronics T3175] Semiconductors 4 IPP075N15N3GXKSA1 150V 100A N-channel Mosfets, TO-220 (Q1, Q2, Q21, Q22) ◆ 4 MPSA92 300V 500mA 625mW PNP transistors, TO-92 (Q3-Q6) ◆ 4 MJE340 300V 500mA 20W NPN transistors, TO-225 (Q7-Q10) ◆ 6 BC546 65V 100mA NPN transistors, TO-92 (Q11, Q12, Q17-Q20) 2 MJE350 300V 500mA 20W PNP transistors, TO-225 (Q14, Q15) ◆ 1 BC556 65V 100mA PNP transistor, TO-92 (Q16) 4 12V 400mW/500mW axial zener diodes, DO-35 (ZD1-ZD4) [Altronics Z0332] 18 BAV21 250V 250mA switching diodes, DO-35 (D1-D18) ◆ Capacitors 2 100nF 50/63/100V ceramic or MKT polyester Resistors (all ±1% ¼W leaded axial) 7 100kW (3 220kW and 4 100kW above ±40V) 4 22kW 2 470W 2 68W 4 1kW 2 220W Substitutions for TO-247 variation 1 double-sided PCB coded 18109262, 76 × 82mm 4 IRFP4668PBF 200V 130A N-channel Mosfets, TO-247 (Q1, Q2, Q21, Q22) Kit (SC7718, $65 + P&P): includes all the parts needed to build the TO-220 version (without the conformal coating; PCB code 18109261). siliconchip.com.au Australia's electronics magazine SMD version 1 double-sided PCB coded 18109263, 66.5 × 68mm 4 5mm pitch PCB-mount 6.3mm vertical spade connectors (CON2-CON5) 1 can of conformal coating spray (optional) [Chemtools CT-ACC-400, Altronics T3175] Semiconductors 4 NTB7D3N15MC 150V 101A N-channel Mosfets, TO-263 (Q1-Q2, Q21-Q22) ◆ 4 MMBTA92 300V 500mA 625mW PNP transistors, SOT-23 (Q3-Q6) ◆ 4 PZTA42 300V 200mA 1W NPN transistors, SOT-223 (Q7-Q10) ◆ 6 BC846 65V 100mA NPN transistors, SOT-23 (Q11, Q12, Q17-Q20) ◆ 2 PZTA92 300V 500mA 1W PNP transistors, SOT-223 (Q14, Q15) ◆ 1 BC856 65V 100mA PNP transistor, SOT-23 (Q16) ◆ 4 12V 400mW/500mW axial zener diodes, DO-35 (ZD1-ZD4) [Altronics Z0332] 18 BAV21W 250V 250mA switching diodes, SOD-123 (D1-D18) ◆ Capacitors 2 100nF 50V X7R M3216/1206-size SMD MLCC Resistors (all ±1% ¼W M3216/1206-size SMD chip type) 7 100kW (3 220kW and 4 100kW above ±40V) 4 22kW 2 470W 2 68W 4 1kW 2 220W Substitutions for TO-220 variation 1 double-sided PCB coded 18109264, 66.5 × 68mm 4 IPP075N15N3GXKSA1 150V 100A N-channel Mosfets, TO-220 (Q1, Q2, Q21, Q22) ◆ ◆ can be purchased from DigiKey or Mouser November 2026  73 Scope 7: testing the Ideal Bridge Rectifier using a 100Hz sinewave from a simple oscillator at 12V peak-to-peak, measured at ZD1’s cathode. With lower-current loads, the mauve waveform (Mosfet gate drive) will be much lower in amplitude. d. Check that the Mosfets are the right way around. 6. You should also be able to independently check the gate drive waveforms on ZD1-4. If one of these looks wrong, check the parts in that section. Using it Remember that inside the case of any high-power amplifier or similar device, there are many parts at very high voltages. When using this Ideal Bridge Rectifier, be aware that: • The tabs on the TO-220/TO-247 Mosfets are connected to their drain pins, which connect to the positive output and AC inputs to the supply. With high rail voltages present in a high-power amplifier, these are electric shock hazards. This device must be packaged inside a closed case and protected from unintended contact in normal use (eg, with an acrylic shield over the top). Scope 8: a similar test to Scope 7, this time for the negative rail, with the gate waveform measured at ZD4’s cathode. This is at a high current; when less current is drawn, the mauve trace will show a lower gate drive voltage. • Never touch the Mosfets to see if they are hot. These Mosfets connect to the filter bank, and this will remain charged after power is removed. Simply switching the power off is not sufficient to make a power supply safe. • High-power DC supplies, especially those with toroidal mains transformers and large capacitor banks, can draw very high inrush currents on startup. • The Mosfets we recommend are extremely tough, but you really should consider a soft-start circuit that puts a resistor in series with the mains side of the transformer for a second or two to reduce the inrush current, such as our SoftStarter project (April 2012 issue; siliconchip.au/Article/705). • We have included reasonable margins for mains supply variation, transformer regulation and a safety margin. Don’t push your luck on This is one of the through-hole versions of the Ideal Bridge Rectifier, using TO-220 package Mosfets for Q1, Q2, Q21 & Q22. The fuse clips are present but there are no fuses installed in these photos. increasing the input AC voltage too high. We have seen our mains voltage go over 260V AC, in excess of the mains standard in Australia, so we feel the extra 10% margin we provided is essential. • This device is intended to be mounted close between your mains transformer and filter bank. You need the filter bank connected for the bridge to operate properly, so keep that in mind. • The PCBs lack a centre-tap ground connection, but you will need to connect the centre tap of the transformer to the centre tap of the filter bank for correct operation. Note the ground connection in Fig.8. • Keep the AC input and DC output wires short, and keep the ground connection bundled with them so that the loop created from the AC input through the bridge to the filter capacitors is small. This will minimise radiated EMI. With these tips in mind, you should be able to reduce the dissipation in your rectifier and save a few volts of drop across it, for just a bit more money than an old-school diode bridge. SC Fig.8: the test setup we used. Our oscillator was set to 200Hz at the maximum undistorted output voltage, which was about 8V RMS. You could use a small audio amplifier to drive the bridge if your signal generator isn’t capable. Test each AC input one at a time and verify both the positive and negative rectified outputs. 74 Silicon Chip Australia's electronics magazine siliconchip.com.au B efore commencing assembly, you will need to choose your USB-PD module to connect via CON5. We recommend our unit based on the AP33772S chip, as long as you have a suitable power supply that provides a PPS output, since the HUSB238-based module does not support PPS. Our article in the previous issue discusses these two modules in detail. You’ll also need a USB-C power supply that supports USB-PPS or USB-PD. We found several units from Ikea’s SJÖSS range that we thought were good value (siliconchip.au/link/acct), although some of them only support USB-PPS up to 16V with a USB-PD (fixed) profile for 20V. We used these for much of our testing. We even found a power bank that supports USB-PPS up to 11V and USB-PD up to 12V. With a suitable power bank, the USB-C PSU does not need to be tethered to a mains connection. Note that like other PSUs without a direct mains connection, the USB-C PSU does not have an Earth connection. You can use a simple DC source if you like. While it won’t be very efficient, it will no doubt be useful in low-current scenarios. If you are using a different enclosure than specified, we suggest you use the bare PCBs to plan and mark out the required holes. There are three mounting holes on the main PCB that can be used to attach M3 hardware. The front panel has 2.5mm holes to suit the fittings included with your chosen enclosure. You could also copy and use the overlay diagrams (Figs.5 & 6) as templates. Construction The main PCB will require the most work since it contains most of the components; it measures 73 × 77mm and is coded 04107261. If you need to program the microcontrollers (IC3 and IC4) in-circuit, keep in mind that some of the programming pins are also used at runtime and are connected to components that may interfere with programming. In that case, we recommend having a look at the next section on PIC programming before starting construction, so you can avoid that problem. If you have pre-programmed chips, no programming step is necessary. There is also the option to program siliconchip.com.au Mighty USB-C Part 2 / 2 Bench PSU We introduced our design for the Mighty USB-C Bench PSU last month, which uses modern USB-C power delivery technology to provide a variable power source and allow efficient operation at different output voltages. Its is designed to reduce the needs for obscure parts, while providing a comprehensive user interface. By Tim Blythman Delivers up to 20V at 2A (if the USB power source is capable) Compact case measures 94 × 83 × 30mm Detailed OLED display plus LED status Rotary encoder for tactile voltage and current control Highly configurable for efficiency or low-noise operation Software features include fuse emulation Detailed USB-PD source information the chips out-of-circuit if you have suitable hardware. You’ll need something like the PIC Programming Adaptor from September 2023 (siliconchip.au/ Article/15943) combined with appropriate SMD-to-DIP adaptors. That article has information about obtaining suitable adaptors. The front panel PCB is fairly compact, so we recommend you keep the enclosure on hand to check that Australia's electronics magazine everything fits as you go. Most of the checks and calibrations should be performed before the unit is secured into the case so that the test points can be accessed. That will require all parts to be fitted and the panel PCB to be connected to the main PCB. Once everything has been checked and calibrated, Q1 and the thermistor need to be affixed to the enclosure using an insulated mounting kit. After November 2026  75 the rear panel is fitted, the PCB is fastened to it using a machine screw. This ensures that the main PCB does not shift and flex Q1’s leads. PIC programming There are two main things to consider if you need to program the PICs in-circuit (after soldering them). Firstly, there are two different chips that run different firmware, so ensure that you don’t mix them up. Also, some of the programming pins have shared roles that might interfere with programming if they are connected to parts of the circuit that will load them. The overlay diagram, Fig.5, shows the components that are necessary for programming marked in blue dashed rectangles. The 10kW resistor and 100nF bypass capacitor for each IC are the minimum parts needed for correct operation, while the CON3 and CON7 headers are needed to connect the programmer. So the simplest approach to programming IC3 and IC4 in-circuit is to fit only these parts first, program the chips, then fit the remaining parts. You’ll also need a suitable programmer, such as a PICkit 4, PICkit 5, Snap or PICkit Basic, plus a power supply if your programmer cannot provide ‘target power’. 5V power can be applied between the TP1 ground test point and the TP3 5V test point. Anything between around 3V and 5V (eg, a 3V coin cell or a pair of 1.5V alkaline cells) should be sufficient for programming. Start with IC4, which is programmed via CON7. Connect the programmer, ensuring that the pin 1 chevron markers are aligned. IC4 is an 8-pin PIC16F18115 and should be programmed with the 0410726B.HEX file; the other hex file should be too large to work. Open the MPLAB IPE, select the part number, connect the programmer (and power supply if needed). Press Connect and ensure communication is working and the chip is identified. Load the HEX file, then perform the Program and Verify steps. Next, program the 20-pin IC3 (PIC16F18146) using a programmer connected to CON3 and the 0410726A. HEX file. It should be possible to program IC3 with all components fitted, but we recommend doing it beforehand in case there are any problems later. Verify the programming, 76 Silicon Chip Like the main PCB, we used a header on the front panel for ease of disassembly. See how we soldered the rotary encoder’s leads and used a short solid-core wire to secure the free end of the OLED module. then disconnect all programmers and power supplies before resuming assembly. Main PCB construction There are many SMD parts in this project, so ensure you have the requisite SMD gear, such as flux paste, solder-­ wicking braid, tweezers and fume extraction. Magnifiers and good illumination are also very helpful. Start with the finer-pitched parts, such as IC1-IC4, REG1 and Q2-Q5. Check each part’s polarity and be sure not to mix up similar parts. All the small transistors come in the same package. Q2-Q4 are BC817 types, while Q5 is a 2N7002 and REG1 is an MCP1700 – all in the same SOT23 package. IC1 is also in the same SOIC-8 package as IC4. Find their locations and orientations on the Fig.5 overlay diagram. Apply flux to each component’s PCB pads, rest each in place and adjust with tweezers. Tack one lead and make sure all the leads are aligned with their pads and the part is flat against the PCB before soldering the remaining leads. Use solder-wicking braid (with extra flux) to draw up any excess solder that results in a bridge between adjacent pads. Follow by fitting diodes D1, D2, D4, D5 and regulator REG2, paying close attention to their polarity and orientation. Note that D4 and D5 face in opposite directions. If you have the surface-mounting version of RLY1, solder it next. Note the bar at one end, which should align with the pin 1 marker dot. Now we can work through the passives according to the parts list and Fig.5. Solitary inductor L1 is not polarised; nor are any of the capacitors. There should be enough space to solder each set of components with the same value without worrying about other parts getting in the way. We suggest starting with the capacitors, since they will not have markings on their bodies, then follow with the resistors. Most of the passives are M3216 (imperial 1206) size at 3.2 × 1.6mm, except for the larger 50mW current shunt resistor. All the SMD parts should now be affixed to the main PCB. It is then a good time to clean off any excess flux using an appropriate solvent. Inspect for bridges and dry joints and rectify as needed. When the main PCB has dried, solder in the fuse clips. You can Fig.5: the main PCB is mostly a straightforward SMD design. If you need to program the microcontrollers in-circuit, you should initially only populate the components in the dashed blue rectangles. You can add the others after programming. Australia's electronics magazine siliconchip.com.au Fig.6: using a PCB as a panel makes for an elegant result but sometimes requires some unusual assembly steps; the OLED module is mounted upside-down using short stubs of wire. Check the clearances with the enclosure during the assembly of this PCB, since the spaces around the OLED module and rotary encoder are quite tight. insert the fuse to ensure the clips are aligned correctly. If RLY1 is a through-hole type, solder it now. Fit Q1 next, with its leads soldered at the very tips and in the orientation shown by the silkscreen markings. Ensure it is mounted squarely to the PCB. Leaving a good amount of lead attached will allow the body of the transistor to be positioned in the enclosure. Have a look at the photos to confirm the arrangement. Note how Q1 has been bent over to near its final position. Once inside the case, the top surface of Q1 is approximately 16mm from the top surface of the PCB. To secure the main PCB inside the enclosure, we have provided a rectangular pad to which an M3 nut can be soldered, adjacent to TP4. The nut will need to be nickel- or zinc-plated, or made of brass, to allow soldering. Ensure that the nut is aligned parallel to the edge of the PCB and take care not to get any solder on the internal threads. If you don’t have a suitable PCB holder, you could slide the PCB partway into the enclosure to support it level and allow access to the underside of the pad. Solder the nut in place and try to get some solder up the sides to form a solid fillet. You can now solder the UBS-PD or USB-PPS module to CON5. We fitted the module under the main PCB to allow room for the thermistor lead to reach Q1. This also keeps the opening for the USB-C lead close to the bottom of the unit. Use the male pin headers, and leave a slight gap above the USB-C socket’s shell so it doesn’t touch the PCB to avoid damage to the solder mask. Trim the leads under the module so that they are well clear of the enclosure. You could solder lead offcuts or other solid-core wire to secure the mounting holes near the USB-C socket. You can now connect a USB supply to the module and check some of the voltages at the test points. Use TP1 as the negative connection for your multimeter. TP4 should be close to 5V, while TP3 will be sitting around 4.7V due to REG2’s dropout voltage. Both of these should be within 0.3V of these values. If not, disconnect the power and double-check everything. TP2 should be between 9V and 11V, probably just under 10V. If this is correct, then IC3 and IC4 are correctly programmed. If you are using a DC supply over 5.5V, there should be a nominal reading at TP4, with TP3 close The location of Q1 and the thermistor is close to that shown here, although the lid of the enclosure and the insulating pad would obscure everything below the head of the screw. The USB-C module mounts under the main PCB to assist with clearance for the thermistor wiring. We fitted headers to our prototype for testing, but we expect constructors will use fixed wiring soldered to the PCB. siliconchip.com.au Australia's electronics magazine to 5V. TP2 should be about 5V higher than TP4, since the default is for the OA+ boost supply to run. Disconnect the power for now and move onto the front panel PCB. Front panel PCB The 0.8mm-thick black front panel PCB is coded 04107264 and measures 29 × 89mm. Before commencing assembly, check if you need to drill out the holes for the output connections. We used rubber grommets to protect wires fed through these holes, but you could drill them out to fit banana sockets or binding posts if you prefer. It will be easier to drill these before the components are fitted. Be sure that there is enough room to fit the hardware, as the panel is quite small. Also take care not to damage the PCB finish or rip any traces off. Drilling the fibreglass PCB should be done with ventilation and respiratory protection. We recommend working outside with a face mask. Test-fit the sockets and ensure that there is clearance to the remainder of the enclosure. Fig.6 is the overlay diagram for the front panel PCB. It has several components fitted in an unusual fashion, so take a close look at the photos and diagram to ensure that everything is installed correctly. Keep the enclosure at hand to check your clearances. Fit IC101, being sure to align the pin 1 dot on the silkscreen to that on the part. Follow with LED101, noting that its dot is in the opposite direction. This part is quite sensitive to heat, so don’t dwell too long with the iron. Follow with the 100nF capacitor and 1kW resistor. Clean off any excess flux. Solder the tactile switches next, with their stems protruding down through the holes. Tack one lead and take time to align each switch stem centrally within the hole. Since the stem and hole will be visible, any misalignment will be apparent. Solder the remaining leads once the position is correct. November 2026  77 Placing the USB-C module underneath the PCB helps with clearance for the thermistor wiring. The nut near Q1 is soldered to the PCB and helps to hold it in place relative to the enclosure so that Q1’s leads don’t flex. The final position of Q1 is very close to what is shown here. This requires the very tips of Q1’s leads to be soldered to the PCB and a bend formed near where the leads exit the body of the transistor. 78 Silicon Chip Australia's electronics magazine To fit the rotary encoder, remove the screw and washer, then carefully bend the leads over so that they will reach the PCB when the encoder is fitted. Use the screw and washer to secure the encoders to the panel. Check the alignment and ensure that it is within the silkscreen markings. When all is well, solder each lead to its corresponding pad. To fit the OLED module, form short pieces of solid-core wire into an L shape. The shorter part of the L should fit within the MOD101 pads. Using tweezers, solder each piece of wire to its pad, with the wire pointing upwards from the centre of the marked outline. Remove the protective film and any headers from the OLED module and ensure the holes are clear, then thread this over the L-shaped wires on the panel PCB. Push the module flat against the panel PCB and gently adjust it as needed to align it with the silkscreen outline. Solder each wire to its corresponding pad and then trim neatly. The single pad between MOD101 and RE101 can be used to solder a short length of wire to secure the other end of the OLED module. Check our photos to see how it should look. The next step will be to connect the two PCBs using hookup wire or similar. Each wire should be about 4-5cm long. Prepare the six wires and solder each one to the back of the panel PCB. Each wire can then be soldered directly back to its matching counterpart on the main PCB. The silkscreen markings can be checked if there is any confusion. The USB-C PSU is now functionally complete, but you will also need to install the thermistor so that no fault is detected. Temporarily screw the thermistor to Q1 so that you can work out the lead length before cutting; our prototype was cut to about 12cm in length. Then bare the leads and solder them directly to the CON4 pads. The thermistor is not polarised. You can leave the thermistor in place for now so that it can detect any thermal problems before final assembly is complete. The thermistor should be insulated from the lug by the potting compound, but you can check this with a multimeter. Testing and calibration Hold one of the panel switches siliconchip.com.au down and apply a USB-C power supply to the CON5 module. The display should light up and show a message as the LED lights up red. If the display shows a “Checking panel” message for more than a second, the front panel PCB may not have been recognised. In that case, check the soldering around IC101 and the wiring back to CON1. The message should show “Panel at: 0x20” for a PCF8574 or 0x38 if a PCF8574A is used. The second line should show that either a HUSB238 or AP33772S was found and indicate the number of USB-PD PDO profiles that were detected. If this shows “DC source” when a USB source is connected, the USB-PD module may not be detected; check the module. Release the switch to allow the software to proceed past this screen. The display should show something similar to Screen 1. If nothing is seen on the display, check the wiring to MOD101. All the displayed values should be sensible. The setpoints and actual values should start out at zero, the temperature shown should be around ambient and the voltages on the bottom line should be about 5V and 4.7V as per TP4 and TP3 earlier. The “L” current-limiting indicator will probably be on, since the current setpoint will be 0A. Controls On the main screen, the rotary encoder controls the voltage or current setpoint according to which is selected by the angle brackets on the first line. Toggle between the two by pressing the rotary encoder to activate its internal switch. Pressing the UP or DOWN buttons should activate or deactivate the relay. When the relay is energised, the LED shows green. If a fault occurs, it is shown on the first line of the display, the relay is switched off and the voltage is forced to a setpoint of 0V. Pressing DOWN will reset the fault indication as long as the fault itself has been cleared. For example, if there is a temperature diately saved to non-volatile memory. There is a setting screen (Screen 7) that can be used to save any changes you’ve made or restore the settings to their defaults. In Settings, the UP and DOWN buttons usually have the same effect as the rotary encoder, although some screens use them for different purposes. #1 PDO listing (Screen 2) Here you can view information about the power data objects supported by your USB power source. Use the rotary encoder to cycle between them. Pressing UP or DOWN will refresh the source PDO listing. If you see NO PDO shown here, the source is not PD-compatible or it couldn’t be detected. A legacy 5V USB or fixed DC source will also show this indication. The specifications of the USB-C we used for much of our testing. Its USB-PPS profiles only allow up to 16V, with a USB-PD profile needed for higher voltages, up to 20V. Source: www.ikea.com fault, the temperature must return to the normal range before the PSU can be reset. For a current trip, you may need to adjust the current setpoint to be above 0A. If multiple trips occur, only one is cleared at a time. This allows you to see if multiple faults have occurred. Pressing the rightmost NEXT button (>) will enter Settings, as long as the output relay is off; you will see the LED flashing if you attempt to enter Settings with the relay on. Each Settings screen is numbered at upper left for ease of navigation. In Settings, the rotary encoder button will go BACK to the previous Settings screen, while the NEXT button will move to the next and then loop around to the main screen. See below for the full range of settings and calibration factors. As long as you have the thermistor connected and mounted to Q1, you can run your own tests on the USB-C PSU assembly to check its operation. The thermistor will detect if Q1 starts overheating. Settings Screens Changes to settings are applied immediately, but they are not imme- #2-5 Operating options (Screen 3) These screens show several operating options that can be toggled by pressing UP or DOWN, or turning the rotary encoder. #2 V Tracking This dictates whether the USB-PD target voltage follows the setpoint or the actual output voltage. The default is to follow the setpoint, which will generally mean a fast response to changes, but lower efficiency (more dissipation) if current limiting is occurring, since the setpoint will be higher than the output voltage in that case. #3 Current mode This determines whether a current-­ limiting event will also switch the relay off. The default mode is simple current limiting. Enabling a trip will cause the relay to open if the current limit is reached. #4 Current set limiting This forces the current limit setpoint to ramp down if it exceeds the capabilities of the active PDO. It is on by default; if switched off, it may result in the power source shutting down if too much current is drawn. 2 3 Screen 1 (left): the main control screen is full of information about the USB supply and transistor temperature, as well as the voltage and current readings you might expect. siliconchip.com.au Australia's electronics magazine November 2026  79 #5 Load last setpoint This causes the voltage and current setpoints to be reloaded at startup. During operation, these are saved to EEPROM within ten seconds if they have changed. The default is to reload these values at startup, but this can be disabled, in which case the setpoints will be set to 0V and 0A at startup. The relay state is not stored; it always starts in the off state. The Mighty USB-C Bench PSU is compact, versatile and easy to use. #6 Temperature Alarm This sets the thermistor temperature at which the temperature display on the main page will start flashing as a warning. All temperatures are displayed in degrees Celsius (°C). #7 Temperature Shutoff (Screen 4) This sets the (higher) temperature at which the output will be disconnected. It’s also possible for an open-circuit thermistor to cause it to trip; this is indicated in the fault message. #8 Voltage Headroom (Screen 5) This sets the amount by which the USB-PD source voltage must exceed the target voltage (decided by #2 V Tracking). A lower value will be more efficient, but may result in a sluggish response to changes if the actual voltage is chosen as the target. Values down to 0.3V should work well as long as the OA+ boost is active. If OA+ boost is switched off, then this may need to be increased (up to 5V) to ensure that the voltage setpoint can be reached. #10 Op amp supply boost (Screen 6) This sets the duty cycle of the PWM supplied to the OA+ supply boost circuit. A value of 0% shuts down the boost circuit (for low-noise operation). The default value of 6% was sufficient to provide 5V of headroom in our testing, but this can be adjusted up to 15% as needed. #11 NV memory (Screen 7) This is effectively an estimate of the quiescent current used by the PSU. It is deducted from the current available from the USB-PD source to calculate how much current is available for the output. The default is 200mA, meaning that a 1.5A source will be limited to a setpoint of 1.3A at the output. This gives the option to save all live settings and calibration values to EEPROM, so they will be reloaded at the next startup. This is done by pressing DOWN. Pressing UP will restore the live and EEPROM settings from a backup in flash memory, so can be used if the settings are corrupted. A successful save or restore will be shown as a message on this screen. After the NV memory screen, the 4 5 #9 Current Headroom 10 remaining settings are mostly for calibration and should not need to be changed after initial setup. Remember to go back and save the following calibration values on the NV memory screen to ensure that the updated values are loaded at boot. #12 & #15 Calibration instructions (Screen 8) These give instructions for the use of the voltage (#13-14) and current (#16-17) calibration screens that follow. Continuing from this screen will activate the relay and output according to preset parameters, so you should only connect a multimeter set to either volts or amps as appropriate. #13-14 Voltage calibration (Screen 9) These pages switch on the relay and 6 12 11 80 Silicon Chip Australia's electronics magazine siliconchip.com.au set the voltage and current limit to suitable levels for trimming the offset (#13) and scale (#14) of the voltage calibration. Ensure that the two displayed voltage values match, then connect a voltmeter to the output. Adjust the offset or scale displayed on the second line until the voltage values match the voltmeter. #13 delivers a voltage near 0V to best trim the offset, while #14 delivers a higher value to allow the scale to be adjusted. The two values interact to a small degree, so it is best to check back on each and make small adjustments until both are satisfactory. #16-17 Current calibration (Screen 10) These are similar to #13-14 except they work with current and thus expect an ammeter to be connected. Ensure that the setpoint and actual values shown match. This means that the PSU output will be current-limited. Be aware that a high current draw will likely cause Q1’s temperature to rise, so if a thermal trip occurs, you can return to #15 to reset the fault. Like the voltage calibration, the two values will interact to a degree, so you should perform a few calibration iterations to confirm the values are correct. thermometer. Switch to the scale (#19) page and apply a high temperature; around 60°C will be sufficient. Adjust the scale to match the reading on the thermometer. Recheck the values to confirm that they are accurate. #20-22 Other voltage calibrations (Screen 12) These voltage measurements do not require an offset, so they can be calibrated by a simple scale value. Use a multimeter to measure the voltage and adjust the calibration parameter until the measured voltage matches the display. Use TP2 (relative to TP1 ground) for #20 OA+, TP3 for #21 +5V and TP4 for #22 IN+. None of these are critical to the operation of the PSU, since they are simply used for warning alerts and user feedback. They will be accurate to within a few percent without calibration. #23 DC Limit (Screen 13) If a DC supply is used, this should be set to the maximum working current of the DC supply. The value is used by the USB-C PSU to calculate the upper limit that the current can be set to if the current setpoint limiting is enabled. the absolute value of the configuration value. #25-26 Calibration setup (Screen 15) The values shown on these screens set the voltages and currents used for the #12-17 calibration steps. They are the raw DAC values that are used to set the voltage and current when the relay is activated, so they should not need to be changed at all. The LO value on the left is set by the rotary encoder, while the HI value on the right is set by the UP and DOWN buttons. In general, the LO values are used for offset factors, to allow the variable to be trimmed close to zero. The HI voltage value is used for the voltage scale factor, with the current set to LO, since a voltmeter will present no load. Similarly, the HI current value is used for the current scale factor, with the voltage set to the LO value, since an ammeter will effectively present a short circuit and require negligible voltage at the output. As long as the voltage and current values on #12-17 are able to be achieved, there is little to no reason to change the values on #25-26. Enclosure These calibrations will probably be unnecessary unless you have a vastly different thermistor, so we don’t recommend changing them otherwise. Like the voltage and current calibration, the temperature is calculated using scale and offset values. For this calibration, you will need an accurate thermometer and a way of changing the temperature of the thermistor over a wide range. Apply a low temperature (around ambient) and adjust the offset (#18) so that the reading matches the This is used to set the direction and steps per detent of the rotary encoder. The UP and DOWN buttons change the configuration value, while rotating the encoder will be reflected in the TEST display. A movement of one detent clockwise should cause the test value to increase by one. Make sure to rotate for several detents to check that there are no missed or extra steps due to rounding. If the movement is backwards (a clockwise motion decreases the value), the sign of the configuration value should be flipped (eg, from -4 to 4). If the test value changes too much, decrease Once you have completed the calibration, disconnect the power supply and unscrew the thermistor from Q1. Bend Q1 over as shown in the photos to allow the PCB to fit into the enclosure. Adjust it so that you can check where the screw will need to be fitted. You will need a hole in the top of the enclosure to attach Q1 for heatsinking, plus two on the back panel, one for the USB-C socket of the USB-PD module and another to thread the screw for securing the PCB. We have provided a drilling diagram (Fig.7) matching our prototype, but you might like to use your assembled PCB to mark out where the holes 7 8 9 13 14 15 #18-19 Temperature calibration (Screen 11) siliconchip.com.au #24 Encoder setup (Screen 14) Australia's electronics magazine November 2026  81 need to be. In particular, it might be better to drill the hole for Q1 to suit its actual location. The panels and enclosure are quite thick but made of fairly soft aluminium. Make sure that the hole for Q1 has no burrs that might short out to its tab, since this will be live at the POWER+ voltage. The easiest way will be to rub a small piece of sandpaper over the inside of the hole and be sure to wipe away any residue. If you are using a DC source, you might need to do something different for the back panel. In that case, we suggest using a panel-mount DC socket with flying leads back to the main PCB. For the flying leads at CON2 or CON6, consider soldering them to the underside of the PCB and feeding them up through the strain relief holes. We are now ready to close everything up. If you haven’t done so already, terminate the leads for the CON2 output and finalise your front panel to suit. Slide the assembly into the enclosure from the front and secure the front panel PCB with the four screws included with the enclosure. The main PCB should be flush with the back edge of the enclosure. Fig.7: it’s best to mark out your panels for drilling by lining them up with the PCBs. The hole for the USB-C socket is shown as rectangular, but you could make it by drilling out a row of round holes with a drill and then leave the corners rounded to match the rounded shape of the socket. Rest the insulating pad on top of Q1 and thread the 12mm-long M3 machine screw in from the outside. Flip the enclosure over so that everything stays in place. Add the thermistor, insulating washer, flat washer and fasten the nut to the screw to hold everything together. The metal tab of Q1 is connected to its collector (and also the POWER+ rail); this must be insulated from the screw and enclosure. You can check this with a multimeter set to measure ohms. Now attach the back panel using the remaining case screws and use the other 6mm-long machine screw to secure the PCB to the back panel. This will prevent the PCB from moving and flexing Q1’s leads when the USB cable is attached and detached. Finally, add rubber feet to prevent the Power Supply from sliding around and scratching your workbench. The PSU is now complete and ready for use. We have set the temperature setpoints to quite conservative values, so you could increase them if you feel comfortable doing so. The electronics can handle somewhat higher temperatures, but the case may get too hot to SC touch at higher levels. 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The USB also comes with its own case THE FIRST SIX BLOCKS COST $100 OR PAY $650 FOR ALL SEVEN (+POSTAGE) NOVEMBER 1987 – DECEMBER 1994 JANUARY 1995 – DECEMBER 1999 JANUARY 2000 – DECEMBER 2004 JANUARY 2005 – DECEMBER 2009 JANUARY 2010 – DECEMBER 2014 JANUARY 2015 – DECEMBER 2019 OUR NEWEST BLOCK OF ISSUES COSTS $150 → JANUARY 2020 – DECEMBER 2024 WWW.SILICONCHIP.COM.AU/SHOP/DIGITAL_PDFS Ordering the USB also provides you with download access for the relevant PDFs, once your order has been processed 82 Silicon Chip Australia's electronics magazine siliconchip.com.au SOnline ilicon Chip Shop Kits, parts and much more www.siliconchip.com.au/Shop/ Simple USB Power Monitor June 2026 Complete Kit SC7683: $50 siliconchip.au/Article/20365 Includes the PCB, all onboard parts and some clear heatshrink tubing to encase it. This unit is not recommended for USB 3.1 PD above 36V. Dual Mini LED Dice August 2024 SMD LED Complete Kit SC6961: $17.50 TH LED Complete Kit SC6849: $17.50 USB Power Adaptors May 2025 Complete Kit with choice of USB socket SC7433: $10 siliconchip.au/Article/16418 siliconchip.au/Article/18112 Includes either 3mm through-hole or 1206sized SMD LEDs. Choice of either white or black PCB. CR2032 coin cell not included. You can choose from one of four USB sockets (USB-C power only, USB-C power+data, mini-B or micro-B). The kit includes all other parts. Compact HiFi Headphone Amplifier Complete Kit SC6885: $70 Human Comfort Indicator June 2026 December 2024 & January 2025 siliconchip.au/Series/432 This kit includes everything required to build the Compact HiFi Headphone Amplifier. The case is included, but you will need your own power supply. Mic the Mouse Complete Kit SC7508: $37.50 August 2025 siliconchip.au/Article/18637 It includes everything needed to build one Mic the Mouse, except for solder, glue and a CR2032 cell. Complete Kit SC7646: $60 siliconchip.au/Article/20362 Includes everything, except for the case and Li-ion cell. You can either use a 3D printed case (available separately) or a UB3 Jiffy box. → Subscribers receive a 10% discount on all purchases, except for subscriptions (postage is not discounted). → Prices listed do not include postage. Postage rates within Australia start at $12, rates are calculated at the checkout. SERVICEMAN’S LOG The Wimmera Boys I was in our factory in Melbourne when Raelene, our Admin Manager, popped her head into the production area and said that a young man was on the phone looking for a job after completing his electronics degree at RMIT in Melbourne. As a hands-on technician without a degree, I rolled my eyes and imagined that the hopeful young man had never seen a soldering iron. Still, I asked Raelene if he mentioned any skills he could bring to our company. She shook her head, but then went on to say he hailed from a farm near Horsham in Victoria. That lightning bolt hit me hard; it meant he had to be a Wimmera farm boy. My reply to Raelene was instantaneous: tell him he has got a job and starts on Monday at 8am sharp! Why are Wimmera boys renowned around the world? We need only remember that they were in the trenches on the Somme, the Kokoda Track and in the mines and drilling rigs in the Pilbara in the 1970s. True to his roots, young Richard turned out to be a stellar engineer. He did circuit design, microprocessor design and heavy code all destined to be exported worldwide in our drink can measurement systems. That is how Richard and I ended up heading north out of Kansas City on Interstate 29, bent on making St Joseph, Missouri before dark. We were due at a large can-making plant to service and update the software on our automatic measurement gauge. The next day, we fronted up at the plant and obediently obeyed the sign asking us to leave our guns in the car before signing in and taking our toolboxes to the plant’s laboratory. The QA Manager said the gauge was running well and left us to it. Richard set about connecting his laptop to start updating the software while I unscrewed panels to inspect the gauge mechanism and calibrate the internal probes and sensors. Things were going well until someone, also a Wimmera Boy, let the screwdriver brush against the MP44 microprocessor board, causing lots of sparks! The gauge jolted, air cylinders stopped mid stroke and the screen instantly displayed the classic black screen of doom! Richard looked stunned and immediately rebooted the gauge – nothing happened. He shook his head and confirmed that I had ‘taken out’ the microprocessor board and that we didn’t have a spare. Items Covered This Month • The Wimmera farm boys • An Acer laptop and a missing battery • Repairing a Simpson washing machine • Installing an irrigation controller • Plus a faulty alarm controller Cartoonist – Louis Decrevel 84 Silicon Chip Website: loueee.com We felt sick – the gauge was running well until we blew it up – our American customer was not going to be happy! What to do? I sat and went through our options; they were all bad. Richard walked around the laboratory and suddenly yelled, “Hey, look up on the shelf at the box with a kangaroo on the side!” He pulled it down, and we saw the words Versatile Technology, Made in Australia on the box. Rummaging through the contents, Richard pulled out a brand-new MP44 microprocessor board. Richard swapped the MP44 boards, and the gauge came up. Now forbidden from approaching the gauge, I watched him calibrate and upgrade the gauge software. The customer was delighted to see a new calibration sticker on his gauge. We told him about the board and that we would be sending a replacement board free of charge. So, what did we learn that day? Firstly, don’t drop a screwdriver on a live board! Secondly, encourage customers to purchase a box of recommended spare parts with their gauges, and thirdly, and most importantly – when all around is doom and gloom, hope that a Wimmera Boy walks into the room! Gerard Dean, Versatile Technology, Oakleigh South, Vic. Acer Aspire 5735Z laptop repair My son came home from town and gave me an Acer Aspire 5735Z laptop that he’d picked up at the Tip Shop. It didn’t have a battery and the lid was jammed shut. Still, I got the lid open by pushing on the broken latch release with a metal rod. With it open, I could see that it was in reasonable condition for a Windows Vista laptop that was 18 years old. Australia's electronics magazine siliconchip.com.au This Acer Aspire 5735Z laptop was purchased without an internal battery, and the lid was jammed shut. I connected a charger and pressed the power button to start it up. Of course, the CMOS battery (cell) was flat. After setting the time and date and rebooting, Windows 7 Enterprise loaded, with a message that Windows was not genuine. I’d be wiping the hard drive anyway, but I clicked on “Ask me later” so I could open Notepad to test the keyboard, which was good, with all the keys working. I also ran msinfo32, which showed that it had an Intel dual-core T3400 CPU at 2.16GHz and 2GB of PC2 RAM. I shut the laptop down, got out my salvaged PC2 RAM and found a matched pair of 2GB modules, then installed them. Now the laptop would not boot. I checked each module and found that one was bad, so I got another matched pair and this time the laptop booted. I turned it over and removed the large back cover, which revealed the hard drive, RAM, Wi-Fi card and CPU heatsink. It would be very easy to upgrade the CPU on this laptop, but I still needed to replace the CMOS CR2032 cell, which was on top of the motherboard. I removed the keyboard, hoping that the cell might be under it, but it wasn’t, so I removed the screws on the bottom of the laptop and started prising the top shell up from the front. I could see the CR2032 cell in a holder not too far in, so I was able to use a tool to flip it out and replace it without having to completely dismantle the laptop. I pressed the top shell back down, turned the laptop over and reinstalled the screws holding the top and bottom shells together. I removed the CPU/GPU heatsink by undoing three screws. I looked online to find what CPUs were supported by this motherboard; the choices were limited, as it has a GL40 chipset, which limits the front-side bus (FSB) to 800MHz. This ruled out using an Intel Core2Duo P8600 CPU at 2.4GHz (1066MHz FSB), but I had an Intel DualCore T4500 CPU at 2.3GHz that I could use. The motherboard supports the Core2Duo T8300 CPU at 2.4GHz but I didn’t have one. Still, I can obtain one for less than $10 from China if I wish to upgrade the CPU later. After researching the performance difference, I decided to order a T8300 from China to upgrade the CPU later. With the T4500 CPU fitted, I cleaned the heatsink, applied new heatsink compound and refitted the heatsink/fan unit. I noticed that the heatsink was completely clean and the fan only had a very slight trace of dust on it, so it may have siliconchip.com.au been cleaned at some time in the past. There was evidence of this large back cover having been removed previously (two of the screws were missing). While working on the laptop, I’d freed up the lid catch, so it now worked. However, the front of the catch was broken off, so it needed to be fixed to make it usable. I looked through some scrap laptop shells and found a serrated piece on one, so I broke it off and filed it to fit in the recess on the lid catch. I carefully glued it in place with superglue, which is ideal for gluing ABS plastic, as it partly melts the plastic, ensuring a good bond. I looked through my salvaged batteries to see if I had a battery to fit this laptop, but I didn’t. I’ve previously wrecked several non-working Acer laptops, but they were completely different models, either with no battery supplied or a completely different type. I looked on eBay for a battery, but they are between $40 and $50, so I won’t be buying one. I’ll just use the laptop with the charger for now. Maybe a battery will turn up later. Australia's electronics magazine November 2026  85 I refitted the keyboard, then booted the Memtest86+ CD to test the newly installed RAM, which passed. Now I could think about installing Linux on the 160GB hard drive that came in the laptop. Whenever I get a second-­ hand laptop, I always erase the hard drive contents. The previous owner probably should have done that but they often don’t. I installed Big Linux, but after restarting, the laptop would not boot. I wanted to have a look at the new Zorin 18.1 distro, so I tried to install it to dual boot, but the installation crashed partway through. I suspected there was something wrong with the hard drive, so I swapped it out for a 320GB drive, but upon reinstalling Big Linux, I saw CD read errors. I knew the disc was fine as I had used it successfully before, so it was the optical drive that was at fault. I swapped in a spare one after changing the faceplate and the bracket on the back, and this time I was able to reinstall Linux. It can be interesting to try different Linux distros and see what they are like. Some of them install more smoothly than others on these old systems. For anyone considering switching from Windows or macOS, it’s better to stick with reliable mainstream distros. While Ubuntu is quite popular, I’ve found it to be somewhat of a learning curve for anyone switching from Windows. Kubuntu or Lubuntu are good for old hardware (especially Lubuntu). Linux Mint Cinnamon, which I’ve installed on my wife’s laptop, is a lot faster than Windows 10. Bruce Pierson, Dundathu, Qld. Simpson 9.5kg washing machine repair My wife told me that she was having trouble opening the lid on our Simpson 9.5kg washing machine. It was jamming at the back and not opening all the way. I soon saw that the right-hand hinge was broken. We have a 7.5kg Simpson washing machine in which the computer died in our boneyard (where we store old washing machines for spare parts). I thought the lid was the same as the 9.5kg washing machine and would fit. So I thought it would be an easy repair. 86 Silicon Chip An internal photo of the Simpson-branded washing machine. I removed the four screws holding on the control panel, lifted up the control panel and moved it behind the machine, resting it on the tub. The lid hinges are held on with four screws, which I removed. I installed the replacement lid and replaced the control panel. However, when I tested the machine, it showed a lid error, indicating that the lid was still open. I checked the old lid and then realised that the lid switch was in a different location on the two machines; this machine had a tongue on the original lid that activated the lid switch and the tongue was also locked by a solenoid when the machine was in use. This did not exist on the 7.5kg machine. I decided that the best course of action would be to rewire this machine. I removed the lid switch from the 7.5kg machine and installed it in the 9.5kg machine. Next, I needed to locate the wires for the original lid switch. I could see that a wiring harness came from the front of the machine and emerged under the computer inside the control panel. After retrieving my multimeter, I started removing plugs, testing for the lid switch while opening and closing the lid. I could not find the wires for the lid switch on the computer, but I could see other wires going to the cycle control board. The plugs on the cycle control board were too small for me to be able to get the multimeter probes into. I decided to use my buzz-box, as it has clips on the leads and I could clip the leads onto two bent paperclips, which would fit in the plugs. I removed the plugs from the cycle control board and checked them while activating the lid switch by raising and lowering the lid. The lid switch wires were soon located – two thin green wires connected to the right-hand plug on the cycle control board. I cut the wires some distance from the plug, then cut the wires from the replacement lid switch to length. Australia's electronics magazine siliconchip.com.au I bared the ends of the wires, soldered them together, then covered the joints with heatshrink tubing. I plugged the plug back into the cycle control board and tested the washing machine to make sure that the lid switch was working correctly. My wife was happy to have the machine back in working order. She was also very happy to be rid of the lid lock, which was an annoyance. When the machine went out of balance and she needed to adjust the washing, she had to wait about 10 seconds for the lid to unlock before she could open it. It was more of a nuisance than a safety feature. It’s just common sense when lifting the lid to wait for the bowl siliconchip.com.au Australia's electronics magazine November 2026  87 to be stationary before putting your hands in to adjust the washing. It’s really handy keeping these old washing machines for spare parts. If I had to buy new parts, the cost would often exceed the value of the old machine. Bruce Pierson, Dundathu, Qld. K-Rain KRC9 irrigation controller installation challenges My daughter asked me to help her partner connect a new irrigation controller at her rental property. She said it would be easy because her partner had put the controller in place and run the cables to the required locations. There was one set of valves in the back garden and one set in the front garden. I asked what controller was being used so I could read up on the details before starting. The manual showed how to wire the valves and set them up. So, I was well prepared when I went to carry out the work. The controller was indeed attached to the wall with two five-core, 20m-long cables run to the location of the back garden valves. A third cable was run across the yard and a fourth down the side of the house to the location for the front garden valves. What I wasn’t told was that, as the cables were supplied as 20m long, the feed to the front garden had two joins to complete the circuit. The front solenoids would be 60m from the controller, but the installation manual indicated that the wiring should be 1mm diameter for runs over 50m. However, the cables that had been purchased and run only had 0.5mm diameter wires. The three solenoids at the front only needed four wires, so I decided to parallel two wires for the common to reduce the voltage drop along the cable and see if that worked. I joined the three cables leading to the front garden together, then shorted the black and white wires at the front garden end so I could identify which of the two cables at the controller end I needed to use for the front valves. The first cable I tested showed the short, so I marked it as the front feed. I then went back and shorted the remaining red, blue 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? It 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 cars and similar. 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. and green wires together to prove the continuity of my joints. All tested OK. We then fitted the master solenoid and two others to a manifold and connected the water supply. I connected the solenoids to the cable running back to the controller. Now satisfied that all should work, I switched on the power and set the water to come on. Nothing happened, although the controller showed a display indicating that water should be running. I then noticed that the fuse in the controller had blown. Did we have a faulty solenoid or was the wiring faulty, despite my testing? I disconnected the solenoids and checked each one; they were all OK. I started my working life installing crossbar telephone exchanges, dealing with thousands of wires; surely I did not make a mistake with five wires! I then went back and double-checked my wiring joins; they all looked good. This was turning out to be very puzzling. I decided to look at the unused cable that was going to be for the back garden. I was amazed to see that the end away from the controller had all the insulation stripped from each wire and all five were shorted together! This was the answer; when I initially shorted the black and white in the front garden and tested it, I was seeing the back garden cable with all the conductors shorted together. Murphy’s Law was at it again. If I had tested the other cable first, all would have been good. I can only assume that all the conductors had been shorted together during testing after manufacturing. It was a simple matter to swap the cables at the controller and test again. To my relief, it all worked well that time. The back garden would have to wait for another day. John Western, Hillarys, WA. Faulty alarm controller The five wires shown inset had the insulation stripped from their ends and were shorted together. 88 Silicon Chip A few months ago, I received a phone call from a neighbor while we were out, informing us that our house alarm was going off, although there was no sign of entry. I hurried back and found the key panel was indicating a battery fault. The base unit is difficult to access, but when I managed to get to it, I found the battery was flat. Interestingly, it felt warm. It had only been replaced once in over 20 years, so I fitted another from a nearby battery retailer (12V 7.2Ah). The fault was cleared, and everything was OK – for about eight days. Until 1:30am, to be precise, when it went off again (sorry, neighbours). With bleary eyes, I checked the battery; it was also flat Australia's electronics magazine siliconchip.com.au Versatile Battery Checker This tool lets you check the condition of most common batteries, such as Li-ion, LiPo, SLA, 9V batteries, AA, AAA, C & D cells; the list goes on. It’s simple to use – just connect the battery to the terminals and its details will be displayed on the OLED readout. Versatile Battery Checker Complete Kit (SC7465, $65+post) Includes all parts and the case required to build the Versatile Battery Checker, except the optional programming header, batteries and glue See the article in the May 2025 issue for more details: siliconchip.au/Article/18121 and warm. I removed the battery and disconnected the AC, put the battery on a charger, and decided to attack it in the morning so that I could resume my beauty sleep (it didn’t work, unfortunately). The next morning, I examined the base unit. I connected the battery through an ammeter and recorded 300mA discharge – that seemed a bit high. I connected the mains input to check if it was charging, but it was still discharging at 50mA! I could see a bulge in the main filter cap, so the board had to come out. As you can see from the photo, there are lots of connectors. This alarm was installed by an electrician over 20 years ago when the house was being built. No doubt there is a map of where they all go somewhere, but I can’t find it, so I photographed it and also drew up a diagram of the wire colour codes and locations. As for the white commons, I marked each one with a different number of stripes using an indelible pen. The chance of replacing a board of that vintage was vanishingly small, and replacing a whole alarm system seemed horrifyingly expensive, so I thought I had better have a go at repairing it. Replacing the bulging capacitor was easy; it was 3300μF, but I replaced it with a 4700μF type I had lying around. It had the same pin spacing, but I knew there was more to it. The bridge rectifier was OK but the readings around the regulator seemed a bit strange. This was attached to the large heatsink on the right. Once removed, it measured 80W with either polarity between the input and output. This was an LM340T three-terminal regulator, which siliconchip.com.au is normally bulletproof. Perhaps trying to regulate a DC voltage with a large AC component proved too much, and it gave up the ghost. Luckily, I had one of them on hand as well. Everything has been good since – I wasn’t looking forward to trying to identify all the inputs if I had to replace it! SC Frank Murray, Downer, ACT. Since Frank Murray didn’t have a wiring diagram for his alarm controller, he took this picture and started marking the wire colour codes. Australia's electronics magazine November 2026  89 SILICON CHIP .com.au/shop ONLINESHOP HOW TO ORDER INTERNET (24/7) PAYPAL (24/7) eMAIL (24/7) MAIL (24/7) PHONE – (9-5:00 AET, Mon-Fri) siliconchip.com.au/Shop silicon<at>siliconchip.com.au silicon<at>siliconchip.com.au PO Box 194, MATRAVILLE, NSW 2036 (02) 9939 3295, +612 for international You can also pay by cheque/money order (Orders by mail only) or bank transfer. Make cheques payable to Silicon Chip. 11/26 YES! You can also order or renew your Silicon Chip subscription via any of these methods as well! The best benefit, apart from the magazine? Subscribers get a 10% discount on all orders for parts. PRE-PROGRAMMED MICROS For a complete list, go to siliconchip.com.au/Shop/9 $10 MICROS $15 MICROS ATtiny85-20PU Graphing Thermometer (Mar26), Simple LC Meter (May26) Simple USB Power Monitor (Jun26), Transceiver Test Set (Aug26) ATmega328PB-AU Low-Power FM Transmitter (Sep26) PIC12F617-I/P Active Mains Soft Starter (Feb23), Model Railway Uncoupler (Jul23) Battery-Powered Model Railway Transmitter (Jan25) PIC16F1455-I/P Battery-Powered Model Railway TH Receiver (Jan25) Dual Train Controller (Transmitter / TH Receiver, Oct25) PIC16F1455-I/SL Battery-Powered Model Railway SMD Receiver (Jan25) USB Programmable Frequency Divider (Feb25) Dual Train Controller (SMD Receiver, Oct25) PIC16LF1455-I/P New GPS-Synchronised Analog Clock (Sep22) PIC16F1459-I/P Mains Power-Up Sequencer (Feb24 | repurposed firmware Jul24) 8CH Learning IR Remote (Oct24), Heat Transfer Controller (Aug25) Vacuum Controller (Oct25), Adjustable Ultrasonic Cleaner (Jul26) PIC16F15214-I/SN Silicon Chirp Cricket (Apr23), Mic The Mouse (Aug25) PIC16F15214-I/P Filament Dryer (Oct24), Tool Safety Timer (May25) PIC16F15224-I/SL Multi-Channel Volume Control (OLED Module; Dec23) NFC IR Keyfob Transmitter (Feb25), Rotating Light (Apr25) PIC16F18115-I/SN Model Railway Destination Display (Aug26) Mighty USB-C Bench PSU (Oct26) PIC16F18126-I/SL RGB LED Star (Dec25), DCC/DC Stepper Motor Driver (Apr26) μDCC Decoder (May26; bell [G] or whistle [W]) PIC16F18146-I/SO Versatile Battery Checker (May25), RGB LED ‘Analog’ Clock (May25) USB-C Power Monitor (Aug25), DCC Remote Controller (Feb26) DCC Booster & Reverse Loop Controller (Mar26) DCC Accessory Decoder (Snap / Servo-type, Jul26) Mighty USB-C Bench PSU (Oct26) STM32G030K6T6 Variable Speed Drive Mk2 (Nov24) PIC16F1847-I/P PIC16F18877-I/PT Digital Capacitance Meter (Jan25) Dual-Channel Breadboard PSU Display Adaptor (Dec22) Wideband Fuel Mixture Display (WFMD; Apr23) PIC16F88-I/P Battery Charge Controller (Jun22), Railway Semaphore (Apr22) PIC24FJ256GA702-I/SS Ohmmeter (Aug22), Advanced SMD Test Tweezers (Feb23) ESR Test Tweezers (Jun24), Human Comfort Indicator (Jun26) PIC32MX170F256D-501P/T 44-pin Micromite Mk2 (Aug14), 4DoF Simulation Seat (Sep19) PIC32MX170F256B-50I/SP Micromite LCD BackPack V1-V3 (Feb16 / May17 / Aug19) Advanced GPS Computer (Jun21), Touchscreen Digital Preamp (Sep21) PIC32MX170F256B-I/SO Battery Multi Logger (Feb21), Battery Manager BackPack (Aug21) PIC32MX270F256B-50I/SP ASCII Video Terminal (Jul14), USB M&K Adaptor (Feb19) STM32L031F6P6 SmartProbe (Jul25) $20 MICROS ATmega32U4 ATmega644PA-AU PIC32MK0128MCA048 PIC32MX270F256D-50I/PT Wii Nunchuk RGB Light Driver (Mar24) AM-FM DDS Signal Generator (May22) Power LCR Meter (Mar25) Digital Preamplifier (Oct25) $25 MICROS PIC32MX170F256B-50I/SO + PIC16F1455-I/SL Micromite Explore-40 (SC5157, Oct24) PIC32MX470F512H-120/PT Micromite Explore 64 (Aug 16), Micromite Plus (Nov16) PIC32MX470F512L-120/PT Micromite Explore 100 (Sep16) $30 MICROS PIC32MX695F512H-80I/PT Touchscreen Audio Recorder (Jun14) PIC32MZ2048EFH064-I/PT DSP Crossover/Equaliser (May19), Low-Distortion DDS (Feb20) DIY Reflow Oven Controller (Apr20), Dual Hybrid Supply (Feb22) KITS, SPECIALISED COMPONENTS ETC NEOPIXEL RGB LED ANALOG CLOCK (SC7752) (NOV 26) Kit: includes everything in the parts list, with the PCB mostly assembled; optional GNSS module available separately (see p33, Nov26) - NEO-7M GNSS module (SC6737; $20) and external antenna (SC6738; $10) - VK2828U7G5LF GNSS module (SC3362) - BZ-121 GNSS module (SC7414) PORTABLE EMF PROBE (SC7715) (NOV 26) HIGH POWER IDEAL BRIDGE RECTIFIER (SC7718) (NOV 26) AUDIO SPOT FREQUENCY TEST GENERATOR (OCT 26) $85.00 $25.00 $30.00 Kit: includes all parts except the case, cell and insulating tape (see p55, Nov26) $30.00 Kit: includes all the parts needed to build the TO-220 version (mostly SMD components) without the conformal coating (see p73, Nov26) $65.00 - 0.96in OLED display module, white (SC6936) or cyan (SC6176) - PCM5102 DAC module (SC7749) - NJM5532D ($3.50, SC7695) or NJM5532DD ($5.00, SC7694) dual op amp MIGHTY USB-C BENCH PSU (SC7739) (OCT 26) Kit: an almost complete kit which includes the case, PCBs, USB-PPS module and all onboard parts (see p33, Oct26) - pre-assembled USB-C PPS control module (SC7740) - 0.91in OLED screen (SC7484) SEMICONDUCTOR ANALYSER (SC7725) $10.00 $10.00 $95.00 $25.00 $7.50 (SEP 26) Kit: includes an assembled PCB with the top-side components already fitted, plus all other non-optional parts except for the case, battery & label (see p32, Sep26) $95.00 - Hammond 1593XBK plastic case (SC7732) $17.50 LOW-POWER FM TRANSMITTER - Elechouse FM transmitter module (SC7712) - 0.96in OLED display module, white (SC6936) or cyan (SC6176) - ND0205MA 3V-to-5V DC step-up converter module (SC7713) (SEP 26) BATTERY BACKPACK KIT (SC7707) (SEP 26) MODEL RAILWAY DESTINATION DISPLAY (SC7697) (AUG 26) Kit: includes all the parts except for a Li-ion cell (see p82, Sep26) Kit: includes all parts, except for the OLED screen (see p54, Aug26) $10.00 $10.00 $5.00 $25.00 $22.50 siliconchip.com.au/Shop/ - 0.32in white OLED screen (SC7698) - 0.50in white OLED screen (SC7699) $5.00 $6.50 DCC ACCESSORY DECODERS (JUL 26) I2C CONTROLLER COMPLETE KIT (SC7690) (JUL 26) HUMAN COMFORT INDICATOR (SC7646) (JUN 26) PINBALL MACHINE KITS (JUN 26) SIMPLE USB POWER MONITOR (SC7683) (JUN 26) SIMPLE LC METER COMPLETE KIT (SC7657) (MAY 26) μDCC DECODER KIT (SC7617) (MAY 26) POWER AMPLIFIER CLIPPING INDICATOR (SC7649) (MAY 26) STEPPER MOTOR DRIVER KIT (SC7601) (APR 26) Snap-type (SC7685): includes the PCB and all non-optional onboard parts Servo-type (SC7686): includes the PCB and all non-optional onboard parts Includes the PCB and all onboard parts (see p83, Jul26) Kit: includes all parts, except the case and battery (see p49, Jun26) - white 3D-printed case: portrait (SC7453) or landscape (SC7684) version - 3.3V GY-BME280 module (SC5482) Control Board (SC7659): includes the PCB and all non-optional onboard parts Power Supply (SC7680): includes the PCB and all onboard parts Cable & Connector Set (SC7681): includes 17 10-pin box headers, 34 10-pin IDC connectors, 10m of 10-way ribbon cable, 30 2-way pluggable terminal blocks and 20 2-way polarised headers Includes the PCB and all onboard parts (see p63, Jun26) - 0.96in OLED display module, white (SC6936) or cyan (SC6176) Includes all the parts and the 3D-printed enclosure (see p67, May26) Includes all the parts and the optional piezo (wire not included). Specify if you want a bell or whistle sound for the microcontroller (see p88, May26) $40.00 $40.00 $30.00 $60.00 $12.50 $10.00 $150.00 $50.00 $65.00 $50.00 $10.00 $45.00 $25.00 Short-form kit: includes the PCB and all onboard parts, the case and power supply are not included (see p35, May26) $95.00 - pair of red & white PCB-mounting RCA sockets (SC2615) $4.00 Includes all required parts for DCC or DC mode (see p55, Apr26) *Prices valid for month of magazine issue only. All prices in Australian dollars and include GST where applicable. # Overseas? Place an order on our website for a quote. $35.00 PRINTED CIRCUIT BOARDS PRINTED CIRCUIT BOARD TO SUIT PROJECT LASER COMMUNICATOR TRANSMITTER ↳ RECEIVER ↳ PROJECT 27 PCB SKILL TESTER 9000 PICO GAMER ESP32-CAM BACKPACK WIFI DDS FUNCTION GENERATOR 10MHz to 1MHz / 1Hz FREQUENCY DIVIDER (BLUE) FAN SPEED CONTROLLER MK2 ESR TEST TWEEZERS (SET OF FOUR, WHITE) DC SUPPLY PROTECTOR (ADJUSTABLE SMD) ↳ ADJUSTABLE THROUGH-HOLE ↳ FIXED THROUGH-HOLE USB-C SERIAL ADAPTOR (BLACK) AUTOMATIC LQ METER MAIN AUTOMATIC LQ METER FRONT PANEL (BLACK) 180-230V DC MOTOR SPEED CONTROLLER STYLOCLONE (CASE VERSION) ↳ STANDALONE VERSION DUAL MINI LED DICE (THROUGH-HOLE LEDs) ↳ SMD LEDs GUITAR PICKGUARD (FENDER JAZZ BASS) ↳ J&D T-STYLE BASS ↳ MUSIC MAN STINGRAY BASS ↳ FENDER TELECASTER COMPACT OLED CLOCK & TIMER USB MIXED-SIGNAL LOGIC ANALYSER (PicoMSA) DISCRETE IDEAL BRIDGE RECTIFIER (TH) ↳ SMD VERSION MICROMITE EXPLORE-40 (BLUE) PICO BACKPACK AUDIO BREAKOUT (with conns.) 8-CHANNEL LEARNING IR REMOTE (BLUE) 3D PRINTER FILAMENT DRYER DUAL-RAIL LOAD PROTECTOR VARIABLE SPEED DRIVE Mk2 (BLACK) FLEXIDICE (RED, PAIR OF PCBs) SURF SOUND SIMULATOR (BLUE) COMPACT HIFI HEADPHONE AMP (BLUE) CAPACITOR DISCHARGER PICO COMPUTER ↳ FRONT PANEL (BLACK) ↳ PWM AUDIO MODULE DIGITAL CAPACITANCE METER 5MHZ 40A CURRENT PROBE (BLACK) BATTERY MODEL RAILWAY TRANSMITTER ↳ THROUGH-HOLE (TH) RECEIVER ↳ SMD RECEIVER ↳ CHARGER USB PROGRAMMABLE FREQUENCY DIVIDER HIGH-BANDWIDTH DIFFERENTIAL PROBE NFC IR KEYFOB TRANSMITTER POWER LCR METER WAVEFORM GENERATOR PICO 2 AUDIO ANALYSER (BLACK) PICO/2/COMPUTER ↳ FRONT & REAR PANELS (BLACK) ROTATING LIGHT (BLACK) 433MHZ TRANSMITTER VERSATILE BATTERY CHECKER ↳ FRONT PANEL (BLACK, 0.8mm) TOOL SAFETY TIMER RGB LED ANALOG CLOCK (BLACK) USB POWER ADAPTOR (BLACK, 1mm) HWS SOLAR DIVERTER PCB & INSULATING PANELS SSB SHORTWAVE RECEIVER PCB SET ↳ FRONT PANEL (BLACK) 433MHz RECEIVER SMARTPROBE ↳ SWD PROGRAMMING ADAPTOR DUCTED HEAT TRANSFER CONTROLLER ↳ TEMPERATURE SENSOR ADAPTOR ↳ CONTROL PANEL MIC THE MOUSE (PCB SET, WHITE) DATE MAR24 MAR24 MAR24 APR24 APR24 APR24 MAY24 MAY24 MAY24 JUN24 JUN24 JUN24 JUN24 JUN24 JUL24 JUL24 JUL24 AUG24 AUG24 AUG24 AUG24 SEP24 SEP24 SEP24 SEP24 SEP24 SEP24 SEP24 SEP24 OCT24 OCT24 OCT24 OCT24 OCT24 NOV24 NOV24 NOV24 DEC24 DEC24 DEC24 DEC24 DEC24 JAN25 JAN25 JAN25 JAN25 JAN25 JAN25 FEB25 FEB25 FEB25 MAR25 MAR25 MAR25 APR25 APR25 APR25 APR25 MAY25 MAY25 MAY25 MAY25 MAY25 JUN25 JUN25 JUN25 JUN25 JUL25 JUL25 AUG25 AUG25 AUG25 AUG25 For a complete list, go to siliconchip.com.au/Shop/8 PCB CODE Price 16102241 $5.00 16102242 $2.50 SC6904 $7.50 08101241 $15.00 08104241 $10.00 07102241 $5.00 04104241 $10.00 04112231 $2.50 10104241 $5.00 SC6963 $10.00 08106241 $2.50 08106242 $2.50 08106243 $2.50 24106241 $2.50 CSE240203A $5.00 CSE240204A $5.00 11104241 $15.00 23106241 $10.00 23106242 $12.50 08103241 $2.50 08103242 $2.50 23109241 $10.00 23109242 $10.00 23109243 $10.00 23109244 $5.00 19101231 $5.00 04109241 $7.50 18108241 $5.00 18108242 $2.50 07106241 $2.50 07101222 $2.50 15108241 $7.50 28110241 $7.50 18109241 $5.00 11111241 $15.00 08107241/2 $5.00 01111241 $10.00 01103241 $7.50 9047-01 $5.00 07112234 $5.00 07112235 $2.50 07112238 $2.50 04111241 $5.00 9049-01 $5.00 09110241 $2.50 09110242 $2.50 09110243 $2.50 09110244 $2.50 04108241 $5.00 9015-D $5.00 15109231 $2.50 04103251 $10.00 04104251 $5.00 04107231 $5.00 07104251 $5.00 07104252/3 $10.00 09101251 $2.50 15103251 $2.50 11104251 $5.00 11104252 $7.50 10104251 $5.00 19101251 $15.00 18101251 $2.50 18110241 $20.00 CSE250202-3 $15.00 CSE250204 $7.50 15103252 $2.50 P9054-04 $5.00 P9045-A $2.50 17101251 $10.00 17101252 $2.50 17101253 $2.50 SC7528 $7.50 PRINTED CIRCUIT BOARD TO SUIT PROJECT USB-C POWER MONITOR (PCB SET, INCLUDES FFC) HOME AUTOMATION SATELLITE PICKIT BASIC POWER BREAKOUT DUAL TRAIN CONTROLLER TRANSMITTER DIGITAL PREAMPLIFIER MAIN PCB (4 LAYERS) ↳ FRONT PANEL CONTROL ↳ POWER SUPPLY VACUUM CONTROLLER MAIN PCB ↳ BLAST GATE ADAPTOR POWER RAIL PROBE RGB LED STAR EARTH RADIO DCC DECODER DCC BASE STATION MAIN PCB ↳ FRONT PANEL REMOTE SPEAKER SWITCH ↳ CONTROL PANEL DCC REMOTE CONTROLLER MAINS HUM NOTCH FILTER MAINS LED INDICATOR DCC BOOSTER / REVERSE LOOP CONTROLLER ↳ FRONT PANEL SOLAR PANEL PROTECTOR (WHITE) GRAPHING THERMOMETER PICOSDR CONTROL PCB ↳ RF PCB ↳ FRONT PANEL (BLACK) DCC/DC STEPPER MOTOR DRIVER CALLIOPE AMPLIFIER MICROMITE AUDIO PLAYER ADD-ON ↳ ALL-IN-ONE μDCC DECODER SIMPLE LC METER WIFI ALARM MONITOR POWER AMPLIFIER CLIPPING INDICATOR PINBALL MACHINE CONTROL BOARD ↳ POWER SUPPLY ↳ PLAYER LED BOARD ↳ SCORE LED BOARD ↳ LED OUTPUT BOARD ↳ BUMPER LED BOARD ↳ CASCADE LED BOARD ↳ SWITCH INPUT BOARD ↳ GENERAL INPUT BOARD ↳ HIGH-CURRENT INTERFACE ↳ ROLLOVER INTERFACE ↳ BUMPER DRIVER SSB TRANSMITTER (MikeOne/Two/Three) SIMPLE USB POWER MONITOR HUMAN COMFORT INDICATOR ADJUSTABLE ULTRASONIC CLEANER MAIN PCB ↳ FRONT PANEL CONTROL PCB SNAP-TYPE DCC ACCESSORY DECODER ↳ SERVO-TYPE I2C CONTROLLER TRANSCEIVER TEST SET RF/AUDIO PCB ↳ CONTROL PCB MODEL RAILWAY DESTINATION DISPLAY ↳ FLEX ANTENNA PCB SEMICONDUCTOR ANALYSER LOW-POWER FM TRANSMITTER ↳ LID (BLACK, 0.8mm) BATTERY BACKPACK MIGHTY USB-C BENCH PSU MAIN PCB ↳ FRONT PANEL AUDIO SPOT FREQUENCY TEST GENERATOR DATE AUG25 SEP25 SEP25 OCT25 OCT25 OCT25 OCT25 OCT25 OCT25 NOV25 DEC25 DEC25 DEC25 JAN26 JAN26 JAN26 JAN26 FEB26 FEB26 FEB26 MAR26 MAR26 MAR26 MAR26 APR26 APR26 APR26 APR26 APR26 APR26 APR26 MAY26 MAY26 MAY26 MAY26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUN26 JUL26 JUL26 JUL26 JUL26 JUL26 AUG26 AUG26 AUG26 AUG26 SEP26 SEP26 SEP26 SEP26 OCT26 OCT26 OCT26 PCB CODE SC7527 15104251 18106251 09110245 01107251 01107252 01107253 10109251 10109252 P9058-1-C 16112251 06110251 09111241 09111243 09111244 01106251 01106252 09111245 01003261 10111251 09111248 09111249 17112251 04102261 CSE251101 CSE251102 CSE251103 09111242 01111212 01110251 01110252 09111247 04103261 01304261 01104261 08107261 08107262 08107263 08107264 08107265 08107266 08107267 08107268 08107269 08107260 08117261 08117262 06103261 04104261 21105261 04105261 04105262 09111254 09111255 09111256 06104261 06104262 09111252 06101233 P9062-1-C CSE260501C CSE260502 11105261 04107261 04107264 04111261 Price $7.50 $3.50 $2.00 $3.00 $30.00 $2.50 $7.50 $10.00 $2.50 $5.00 $12.50 $5.00 $2.50 $5.00 $5.00 $5.00 $2.50 $5.00 $7.50 $2.50 $5.00 $5.00 $7.50 $3.00 $5.00 $5.00 $7.50 $2.00 $5.00 $2.50 $5.00 $1.50 $2.50 $2.50 $15.00 $25.00 $7.50 $2.50 $5.00 $2.50 $5.00 $5.00 $2.50 $2.50 $2.50 $2.50 $5.00 $2.50 $5.00 $5.00 $7.50 $5.00 $3.00 $3.00 $3.00 $5.00 $5.00 $2.00 $2.00 $7.50 $5.00 $5.00 $3.00 $5.00 $5.00 $5.00 NEOPIXEL RGB LED ‘ANALOG’ CLOCK (WHITE) PORTABLE EMF PROBE IDEAL BRIDGE RECTIFIER ↳ TO-246 VERSION ↳ SMD TO-263 VERSION ↳ SMD TO-220 VERSION NOV26 NOV26 NOV26 NOV26 NOV26 NOV26 19101252 04109261 18109261 18109262 18109263 18109264 $15.00 $5.00 $5.00 $5.00 $5.00 $5.00 NEW PCBs We also sell the Silicon Chip PDFs on USB, RTV&H USB, Vintage Radio USB and more at siliconchip.com.au/Shop/3 1970s-style, lightweight Bass Guita tar Valve AM MP If there’s one place valves are still used extensively, it’s in musical instrument amplifiers, where their soft overload characteristics and non-linearities are not just desirable but critical to the sound. This bass amp has a pretty simple circuit, but it makes an excellent practice amp. Vintage Electronics by Fred Lever T he Fender Bassman article by Brandon Speedie (April 2024 issue; siliconchip.au/Article/16218) struck a chord with me (no pun intended). In the 1970s, I made dozens of “Woden” bass amplifiers, first with valves and then transistors. I used amplifier designs from the electronic magazines of the time, and 92 Silicon Chip recommendations from the valve manufacturers, modified to suit what I thought was the way to go. One thing I never did make was a classic all-in-one small valve bass amp like the Fender. Most of my amplifiers were head units that could sit in a rack or on a speaker box. The speaker box used may have Australia's electronics magazine been an existing unit or made using 12-inch (300mm) or 15-inch (380mm) drivers. An amplifier the size of the Fender Bassman was OK for small stage use or for practising, but would not fill a venue with driving bass. If that was required, a Fender could be monitored with a microphone and that signal fed to a bigger amplifier. The other aspect of a Bassman amplifier was the fabled Fender ‘tone stack’. I never fitted any more than the regular cut and boost or an equaliser to my amplifiers. Guitarists inserted voice boxes and equaliser preamps of their own into the signal path to shape the music, and my amplifiers really just provided the ‘guts’ to fill the audience area with sound. The ‘tone stack’, combined with the all-valve lineup, was a bit of a mystery to me. So it was finally the time to make the effort to build one and find out. This amplifier is a nice matching unit for a 1960s-style lightweight bass guitar I made, as you can see in the lead photo. I found a modern 9kg solid-­body bass guitar just too heavy to wear standing, so made a ‘stick’ bass. I grafted a ready-made stock fretboard, pickup and string fittings onto a length of Tasmanian Oak and completed the body with three-ply, giving a total weight of 5kg. My amplifier cabinet here is similar to the Fender Bassman in that it has a 15-inch single speaker with the amplifier head built into the top of the assembly. Unlike the Fender, I refuse to mount valves upside down; I hate valves falling into the cabinet during transport! So I decided to make a two-part assembly with the valves and heavy parts in a normal chassis that slides into place on cleats, and a horizontal upper panel with all the controls on it. I have some 6DQ6 TV sweep valves and plenty of 12xx7 twin triodes, so I used those and wired them up in a manner very close to the Bassman circuit shown on page 91 of the April 2024 issue. I did make some changes to suit the parts on hand, mainly the 6DQ6 valves. As the output valves determined what sort of transformers were needed, I decided to start there and wind my own, having the necessary wire, laminations and a winding machine. In the March 1962 Radiotronics application notes, Class-AB audio operation of 6DQ6 valves requires a siliconchip.com.au plate (HT) of 440V DC and a screen voltage of 200V DC. That results in a single output pair giving a theoretical 80W when biased with about -40V into a load of 3.6kW. The notes indicate a valve draw of 300mA, so I budgeted for a total of 350mA HT at 440V DC. Add the total heater consumption of about 5A at 6V and the required power transformer rating is 184VA. I confirmed this assessment by finding my chassis build notes of some bass amplifiers with 6DQ6s I built back in the 1970s and checking what transformers I wound then. Unlike the Fender circuit, with one valve rectifier and the full voltage applied to the plates and screen droppers, I used two silicon bridge rectifiers in a two-winding stacked supply to give 200V and 450V. Doing that reduces the voltage applied to each rectifier and the smoothing capacitors. Otherwise, I followed the Fender plan, with the 12AX7 phase splitter driving the output valves, the 12AX7 direct-coupled ‘Fender stack’ tone controls and the 12AY7 high- and lowlevel preamplifier. The output transformer had the primary winding for each valve wound bifilar to provide equal impedances for the valves. While home constructors can safely make their own inter-stage or output transformers, they should not attempt mains transformers since the safety requirements are critical. Given the relatively odd set of voltages required for this build (2 × 6V, 40V, 160V & 210V), to use off-theshelf transformers, you would likely need several with the primaries wired in parallel. A good source of possibly suitable transformers in Australia is: www.antekinc.com/power-­ transformers Failing that, there are local manufacturers like Harbuch Electronics (www. harbuch.com.au) and TorTech Pty Ltd (www.tortech.com.au) that can make custom transformers for you. Evatco also sell Hammond-branded transformers, which are well suited for valve amplifiers (www.evatco.com.au/ transformers). If you can’t get the exact voltages I used, you have the option of using slightly higher voltages (based on what’s available) and adding wirewound resistors to drop the voltages to be closer to mine. If doing this, make sure to over-rate the resistors for siliconchip.com.au dissipation and mount them so that the extra heat won’t cook anything critical! More on sourcing transformers later; first, let’s look at what I built. The chassis I made the steel bottom section with the transformers and output valve stages at one end and the input valve stages at the other end – see Photo 1. The chassis is made of some scrap 1mm sheet steel pieces I had, about 400 × 200mm. I bent and drilled one of those to my rough circuit layout and put plenty of holes in the surfaces to take all the parts my circuit indicated were needed. For the top control panel, I chalked in logical groups of parts with the signal flowing from the input sockets on the left, through the volume and tone controls in the centre. The power switches, fuse and a line output jack are on the right-hand side, above the output valves and transformers. A modern designer would make a 3D CAD drawing and place the parts. An old builder like me looks at the proposed circuit, shuffles the parts around on the chassis surface until they all fit, then draws centre lines, punches them and cuts holes. I sanded the metal until it was bright, washed it down with Prepsol and sprayed on a coat of plain grey epoxy anti-rust paint. Referring to Photo 2, the signal comes in through the phono jack sockets on the left and down to the lower chassis, then travels straight across through the preamp, tone control and phase splitter valves. The signal stream tees back out through holes next to the mini 9-pin valve sockets, up to the tone control groups. All that wiring is shielded to minimise hum pickup. The output valves are next, feeding down to the output transformer. The plate wires come straight out of the transformer, directly to the valve cap fittings. Photo 1: the drilled and painted chassis, ready for components to be installed. Photo 2: the control panel mounts right above the chassis. Australia's electronics magazine November 2026  93 Photo 3: I was able to keep the smaller components under the chassis fairly neat. Leakage in the old Bakelite tag strips caused me some problems, though! The two items next to the output valves are the bridge rectifiers, with the power transformer below. I used ceramic sockets for the hot high-voltage high-power items; I learned that lesson very early on. The bridge rectifiers are soldered into plug-in bases with an idea of possibly hiding them later in defunct valves for that vintage envelope look. The mains power controls are on the right-hand side of the top panel. Getting the output stage going I wired up the mains supply and output stages first to check that my old valves worked and the transformers were satisfactory. After some initial problems using 50-year-old parts (unformed electrolytics, weak valves, failing minor components), the output pair came to life and a load test showed my transformers were on the mark for voltages and the output impedance conversion. On a straight power output test, the HT supply drooped to 430V/190V for the 6DQ6 pair with a 60W continuous sinewave into 8W (resistive) at clipping. That meant I could call the amplifier a 60W unit. The HT power supply droops nicely, being 460V/210V with no load to 430V/190V on load. The 6DQ6 valves go gracefully into overload, with bags of low order harmonic distortion, which is exactly what you want for an electric guitar or bass (see Scopes 1 & 2). Hifi enthusiasts would faint at 30% THD, while 94 Silicon Chip guitarists just turn the volume knob to 11 to get more! In Scope 1, the yellow trace is the sine input and the cyan trace is the speaker output. The valves are starting to clip and distort on the flanks. In Scope 2, the yellow input level has just about doubled, but the output has just clipped off, with loads of flank distortion but no more sound level. All that changes is the tone; the string note sounds more like a raspy woodwind instrument. In Fig.1, the cyan curve is the maximum output with a 60Hz input sinewave with the load varied from 2W to 16W. The amplifier’s power delivery is pretty flat from 6W to 10W, ideal for an 8W speaker load. Fig.1: the cyan curve shows how the amplifier’s output power varies with the load impedance/resistance at 60Hz, while the red curve is its frequency response at around 40W average output. Maximum power is with a load of around 8-9W, so an 8W loudspeaker is the ideal choice. Australia's electronics magazine The red curve is the frequency response from 30Hz to 6000Hz at about 40W. Under 100Hz, the output sinks like a stone due to high-pass (AC-­coupling) filter roll-offs and transformer saturation. Above 1kHz, lowpass roll-offs do likewise; the amp is pretty much mute above 10kHz. Pre-amp stages The preamps worked as expected, apart from a hair-tearing time where leakage in the old Bakelite tag board caused havoc with the high-­impedance volume control circuits. The Bakelite had measurable resistance in the megohms range between the tags that the 12AY7 plate coupling capacitors and grid feeds were terminated onto. That put ‘ghost resistances’ into the potentiometer connections, and the volume controls interacted weirdly with each other. Turning one channel volume down would cause the other channel volume level to rise! Shifting those wires onto a new piece of tag board restored sanity. With that problem out of the way, I checked each stage for gain and measured the overall sensitivity. The full volume sensitivity with the tone controls at their mid positions was around 20mV for a 60W output on the number 1 low-level input. With a 60Hz sinewave input, the 12AY7 had a gain of 7 times from jack socket to plate; the 12AX7 had about 40 times from its grid to plate; the phase inverter 12AX7 about 17 siliconchip.com.au times; and the 6DQ6, about 12 times. Of course, there are insertion losses between each stage. An input of 20mV input yields 20V across the speaker coil. This gives an overall gain of about 1000 times. The ‘Fender tone stack’ I swept the input signal to the amplifier with a sinewave from 10Hz to 2kHz (remember, this is a bass amplifier) to get an idea of the effect of the controls on the frequency response. The reading CRO is connected across the speaker voice coil. There is an excellent article describing these tone controls in Silicon Chip, April 2024, on page 90. My controls may not do exactly what is described in the magazine, but they do something fairly logical. All the controls interact with each other. Scopes 3-10 were made with all the controls set to mid position as default and then one control moved up or down. The bass, mid and treble controls all work as you would expect, but the Presence control is the odd one. Being in the feedback loop, it affects the overall level as well as boosting the midrange and bass. So, you have four controls that interact with each other. A guitarist just turns the knobs until the sound is ‘right’. Scope 1: the input (yellow) and output (cyan) waveforms at the onset of clipping (60W in 8W). Scope 2: the same waveforms as in Scope 1 but with the level pushed up well into clipping. 3 4 5 6 7 8 9 10 Chassis assembly I mounted two long tag strips across the chassis, intending to place most of the parts onto them. On the right in Photo 3, the power transformer connections and bias rectifier parts use the majority of the strip. I used 0.75mm V90 mains-rated flexible cable, not radio hookup wire, for the power and HT wiring. For the signal connections, I used ordinary hookup or shielded wire. The HT filter capacitors are mounted in the centre, along with the various HT dropper resistors and smaller filter capacitors. Using the tag strip to mount the parts around the preamp valves was a disaster, as mentioned earlier. The Bakelite exhibited measurable leakage of a few megohms between tags. This phantom leakage played havoc with high-impedance parts of the circuit, so in the end, I connected most of the signal components point-to-point on the valve sockets. I also mounted a new, small strip on the back panel to provide points siliconchip.com.au Scopes 3-10: these sweeps show how the frequency response changes with each tone control adjustment. From top-to-bottom, left-to-right they are: bass down, bass up, treble down, treble up, midrange down, midrange up, presence down & presence up. Australia's electronics magazine November 2026  95 for high-impedance signal wires that couldn’t be run directly. I ran an Earth bar across the chassis from the mains Earth stud on the righthand side over to the left, securing the bars with lugs bolted into unused holes. Small components could then be mounted from the valve sockets to Earth. The heater wires were connected with two-pair twisted wire. Later on, during testing, each side of the heater supply was linked to Earth to test for the lowest hum level on full volume. On both supplies, Earthing one particular side of the heaters gave far quieter results than the other. To reduce the mains hum pickup, all the signal leads teeing off to go to the front panel were shielded, with the braid at one end only connected to Earth via the bus bar. Most of the small components are from Jaycar. The valves, valve sockets and main electrolytics were new-old stock from the 1960s. All resistors are large-body, 1W ±5% types. Under the top panel (Photo 4), the controls have the associated small components mounted directly onto them; the signal phono jacks are on the right, with the tone stack controls in the centre. All the mains-rated power wiring was spaced well away to the left. Any exposed power connections were sleeved with heatshrink tubing. The chassis could be a conventional front panel layout, with much shorter wiring between the controls and the valves. The layout used here was simply something I had not done before, and I wanted to give it a go. As long as common sense is used, the layout is not critical. In Photo 4, you will note a spring bar arrangement between the two valves. The spring and bar exert a small pressure via the top caps. This is to ensure the top cap lead does not pop off from an impact during transit. A plate lead coming off means a glowing screen and a ruined valve. I prefer the extra expense of the spring assembly over a warranty call. The chrome handle at the back of the chassis is a grip point so you don’t put your fingers into the HV area when lifting the chassis out. Making the speaker box I dropped into Bunnings and bought a couple of sheets of ‘marine’ five-ply and eight lengths of 20 × 10mm rectangular bar. The design process started with a front speaker panel just wide enough to mount a 15-inch speaker inside a frame; everything else was sized from that. I placed a 15-inch old-stock speaker onto a five-ply sheet and figured I could fit the chassis and speaker into a 600mm-high, 460mm-wide and 225mm-deep box, making a simple open-back cabinet. I cut the front speaker panel to 600 × 400mm and then made a flat bar rectangular frame to fit that. This frame has butt joints screwed and glued together. For the wood, I would recommend using Titebond wood glue, which you can find online without much trouble. The next step was to cut the hole for the speaker in the front panel and glue the panel to the frame (see Photos 5 & 6). Then I plated the sides and bottom with sheets, leaving the top open for the control panel. To allow the chassis assembly to slide in, I cut the top rear bar out of the frame once the glue had set and the frame was solid. I added the necessary slide rails to carry the weight of the amplifier assembly and a removable rear panel to trap the whole chassis assembly into place. Photos 7 & 8 are views of the amplifier during construction. No thought was given to speaker box parameters or acoustics. This “Fender” is an open-back plywood box with all the back wave cancellation, resonances and foldback built in at no extra cost! I coloured the cabinet in the same style as the guitar, mainly in red with some black contrasts. I simply painted the timber cabinet with a Cherry Red enamel spray can from Bunnings (the horror!). The first step was to spray the inside with matte blackboard paint and continue the black to the outside in a few places. The surfaces that were going to get red were undercoated with two brushed coats of wood sealer. I cut that back with 120-grit sandpaper to smooth out some of the rough areas. I emptied a full can of Cherry Red spray over the box in two coats. First came a tack-dry coat, then a second layer as thick as I dared; the can ran out just as I finished. I left it for a day Photo 4: a better view of how the front panel controls and connectors are wired into the chassis. The spring contraption stops the valve caps from falling off if the unit gets rough handling – as such gear often does! 96 Silicon Chip Australia's electronics magazine siliconchip.com.au Photos 5 & 6: the cabinet frame after I cut out the loudspeaker hole but before I attached the side panels. And another photo with the 15-inch (380mm) speaker driver mounted. to cure. I did not touch the surfaces with abrasive paper after that; I wanted a slightly rough texture all over. All sanding back does is expose more imperfections in the surface, and there are plenty of those with scratches, nail heads, hammer and saw mishaps. This is definitely not a craft finish, but an ‘industrial’ treatment, as is the guitar. Someone building a similar cabinet could use a vinyl wrap as an alternative. Back in the old days, we glued black ‘leatherette’ straight over the bare wood. That covered up any stray holes and imperfections, and it can be stretched to pull around corners and held down with suitcase corners and tacks if necessary. A bit of added ‘bling’ is the name “Woden” in modest 3-inch (76mm) letters across the box front and a card on the control panel depicting the control positions and Mr Woden wielding a four-string axe (see Photos 9 & 10 overleaf). The loudspeaker I started by using a very old (1980s) Jaycar 15-inch loudspeaker (Cat CG2382) with a two-inch (50mm) voice coil as a trial for measurements, and left that in place to see how it would perform on actual guitar playing. The answer was: terrible. The speaker was a reject, having a loose magnet, with the voice coil rubbing slightly. The basket on those 1980s speakers was just too flimsy; even being dropped while in the shipping box could knock the magnet crooked. I straightened the frame and epoxied the magnet into place. That made the speaker usable, but on playing tests, it was pretty ordinary. siliconchip.com.au Photo 7: the chassis installed in the frame with the side & back panels now attached. Photo 8: a better view of the internals with the back panel removed. I bought a cost-effective Celestion TF1525 unit with a 2.5-inch (63.5mm) voice coil and 200W rating. With a proper bass guitarist pushing the strings, the Celestion driver was way superior to the ancient driver. Overall, the tone balance was biased more to the bass end, but not so much as to skew the tone balance of the guitar fretboard. The big difference was the more direct translation of the strings and fingering and a lack of colouration by the speaker cone. That is the difference between Australia's electronics magazine November 2026  97 making a noise and making music. The Celestion speaker has a variable radius section, smooth cone that works much better compared to the basic flat-with-corrugations surface of the old unit. The Celestion cone moved freely, unsupported by any box back-loading, but did not sound like it was pushed into non-linearity on larger excursions. The valves are already doing that nicely, running near their maximum output. The amplifier simply cannot provide anything more than about 100W of power to the speaker cone. I am confident that the speaker can take that all night with minimal heating, so it is in no danger in this build. The speaker is fixed ‘back of panel’, not with wood screws, but with largeheaded through-bolts, to ensure the basket is clamped down tightly and cannot move or vibrate. A stock 15-inch mesh speaker protection grille is attached to the timber on the outside to give the cone some accident protection, as well as neatening the look of the speaker cut-out, and covering unused spare holes. The bass guitar The guitar is based on a solid-body bass kit from Pit Bull (similar to the kit reviewed by Keith Walters in the November 2017 issue; siliconchip. au/Article/10870). I did not use the heavier solid body that comes with the kit, but bonded the kit neck onto a beam of Tasmanian Oak (Photo 11) and made a hollow body. The hollow body was constructed from marine three-ply and simply serves to give some shape. The body has no other function, and could have been a triangle, star shape or none at all as it has no musical function (the Steinberger electric bass famously has a tiny body, just enough to hold on to). The fretboard neck is screwed and epoxied into a socket in the slab of oak (see Photo 12). That makes an almost continuous backbone for the strings to stretch from the anchor plate to the tuning pegs. The three-ply body is shaped and screwed into blocks glued around the body perimeter. The oak plank has recesses chiseled out for the pickups and anchor plate. I copied the overall dimensions from a finished kit so the string height and length were standard. The weight saving comes from losing the equivalent of about half the volume of the solid body. I also added some thumb rests. Keeping it simple, the only control is one volume control with the two pickups wired in series through the potentiometer to a standard phone jack socket. A builder may consider using a more complex tone and pickup combinations, such as those described by Brandon Speedie in September 2024 (siliconchip.au/Article/16581). I stained the oak and ply with clear varnish tinted with Cherry Red enamel. I applied enough coats to fill Photos 9 & 10: the finished amplifier looking spiffy with its Woden-themed artwork. And of course the knobs go all the way up to 11! 98 Silicon Chip siliconchip.com.au Fig.2: the circuit uses a tried and tested configuration, with twin triode V1 acting as the preamplifier and twin triode V2 providing further amplification. The output of V2 feeds into the tone control network, then to V3, which acts as a phase splitter to drive the output valves, V4 & V5. Warning: all the HT rails in this circuit (150V, 180V, 200V, 250V, 325V, 380V, 460V etc) carry lethal voltages when the circuit is powered and for some time after. All wiring must have a suitable high voltage rating and all joints need to be insulated properly. Do not make contact with any part of the circuit while power is applied. the wood grain until a smooth finish was achieved. The side section was filled with a band of alloy strip, adding to the ‘homemade’ 1970s feel, as seen in Photo 13. A normal shoulder strap with stud attachments sufficed for the weight. Making one of your own Making a valve amplifier nowadays will be dictated by which output valves you use and then sourcing output and power transformers to match the valve impedance and voltage requirements. I used the 6DQ6 valves here because I had them and had used them before (see my circuit diagram, shown in Fig.2). siliconchip.com.au Photo 11: this is essentially a complete electric bass – just a little hard to hold on to! Australia's electronics magazine Photo 12: gluing and screwing the fretboard neck onto the panel that will be the back of the guitar. November 2026  99 They were also used in an Electronic Australia guitar amplifier in June and July 1967 by Tony Leo, called the Playmaster 116 & 117. Those articles are worth reading; you may prefer the tone controls or even the complete circuit they used. While the 6DQ6 is basically a TV sweep generator, the maker was happy for it to be used as a linear amplifier. The smaller 6CM5 was not a good valve for audio work, basically being a switchmode valve. I know they were used by AWA in commercial PA amplifiers, but I had no luck in getting consistent results. There is a raft of other big valves you can use, like the KT66, that sell for silly amounts. In later Woden builds, my go-to valve was the 6CA7. These yielded about 90W per pair with 700V on the plates. They would work well in this circuit; all the connections are via base pins, so you can keep the killer voltages inside the chassis. Once you have your proposed valves, consider the transformers. If you can wind your own, the problem is solved. There are some interesting websites that detail the use of stock power transformers as output transformers, using either a single unit with a centre-tapped primary or two transformers (try a web search for “cheap output transformers”). Suppliers such as Evatco list sensible units such as their 1750L for around $200-300. Keep in mind that this is a guitar amplifier, and very expensive high-­ fidelity transformers are not needed. Power transformers with 6.3V heater windings and useful HT windings abounded in old valve TV sets. What could feed a B/W TV containing a 6DQ6/6CM5 sweep valve and a dozen other 9-pin valves is going to have enough wattage for any small guitar amplifier. Alternatively, transformers always bob up on eBay and other auction sites. New transformers can be bought for large amounts of money. With the valves and transformers sorted, the rest of the parts can be straight from Jaycar, Altronics or other suppliers on the web. The thing with a guitar amplifier is that nothing is critical. The parts can be ±5% or ±10% tolerance; achieving flat responses and perfect linearity is not important. As for the fabled ‘Fender Stack’ tone controls, well, you can take your pick and use those or just put in a Baxandall bass and treble set like the PM117. A bass player will just set their pickups and any tone controls to get the ‘right’ sound. The chassis can be a conventional design with the controls on the front, just like the PM117. The actual dimensions of the chassis will be dictated mainly by the size of the transformers; the speaker box and amp box can be all-in-one. My theory for bass is that you want mass in the box, so the box and speaker frame stand still and only the cone vibrates. A light box with a weak front panel can have the cone tending to stand still and the panel and box vibrate! That isn’t the most efficient or accurate way to promote bass sound waves. My Woden FB60 weighs in at 20kg. It needs a trolley to move it, or a big roadie, but the box does not flap around. Building the system into separate head and speaker boxes makes it easier to transport. Since making the Bassman replica amplifier, I spent a significant amount of time investigating sources of power transformers, output transformers and output valves that may be used in a modern guitar amplifier. Power transformers I came to the conclusion that there are a lot of ex radiogram and television power transformers that can be pressed into service. In their former use, these provided a 250V HT rail and lit up a dozen or more 6/12V valves, similar to the wattage load of a 50W guitar amplifier. A doubler or tripler may be used to get a higher HT value. Of course, you can always buy a new transformer to suit your valves from a supplier like Evatco. Output transformers The field here is limited. You are pretty much stuck with buying a purpose-made unit from Evatco or finding one. I tested some alternatives, such as using stock power transformers. There are limitations and drawbacks to this idea but they can be made to work. Alternatively, you can use a transistor based amplifier as the final stage, giving a so-called ‘hybrid’ design. However, then you lose a lot of the character of the valve amplifier that’s so desirable to musicians. Photo 13: the completed bass guitar. It weighs about half of a solid-bodied equivalent. 100 Silicon Chip Australia's electronics magazine Output valves While any high-power tetrode or pentode will work, the best value valve to use is the 6CA7 tetrode, also known as the EL34 pentode. These were the workhorse valve in the olden days and nowadays are still available at a cost-effective price. For guitar work, odd pairs are fine – matched pairs are not needed. I have bought single valves for as little as $40 each from various sources, so I suggest these are the valves to use. This article is a condensation of two main projects lodged on the Vintage Radio forum website, see https://vintage-radio.com.au/default. SC asp?f=12&th=139 siliconchip.com.au 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 Semiconductor Tester hfe measurement I have ordered the Semiconductor Analyser kit (September 2026 issue; siliconchip.au/Article/20718) and have some comments and questions. 1. Units to do the same job are somewhat plentiful on Amazon, AliExpress and all the usual suspects prices from the low $20s up. I have no idea about their accuracy, though. 2. They all seem to have the same limitation, that is, the collector current at which the measurement is done varies quite considerably even between transistors of the same type. I’d expect this of the simpler testers, as the hfe value varies with collector current. This makes the unit suitable for transistor testing only, not for characterisation, in my opinion. 3. I’m looking for a unit that I can use for characterisation that works as follows: a. Set the maximum values for Ic and Vce. There would have to be sensible limits for these. b. Start the test. The unit ramps up Vce, then ramps up Vbe until the Ic is reached. c. The unit then presents Vbe and hfe at a minimum. Higher-power devices could be accommodated using external power supplies, such as your units. As far as I can tell, you’d get better matches for transistors using this method. I don’t have the expertise to create such a beast. How does this compare to your Tester? I built the kit and it works. When I connected a 2SC5242 to it, the hfe reading varied between 78 and 83 from one test to another. The Vbe stayed constant. Once a test is complete, the screen stays on for about 10 seconds, then switches off. I’ll test some other transistors later. It would be good if when you’re running off batteries it switched off, say, after 20 seconds and, if you’re running it off the USB port that it stays on until either you hit the test button siliconchip.com.au again or disconnect the USB port. (K. J., Cleveland, Qld) ● Andrew Levido responds: The Semiconductor Analyser does work largely as you suggest, with two exceptions described in brackets below. Using the step numbering in your email: 1. Vce is limited to a maximum of 12V and Ic is limited to a maximum of around 10mA. 2. Ib (not Vbe) is ramped up until the collector current is in the range 8.5 ±0.5 mA. The code uses a binary search algorithm to find the value of base current that puts the collector current into the target range, because this is much faster than a linear search given several decades of base current range. 3. The hfe and the actual collector current are displayed. The upshot is that all hfe measurements are taken with Vce of 3.5 ±0.5V and an Ic of 8.5 ± 0.5mA, so comparisons across similar devices should be meaningful. An hfe range between 78 and 85 on one transistor across multiple tests is about what I’d expect, given the collector current can vary from 8mA to 9mA from test to test. I could have made this tighter, but it increases the risk that the algorithm fails to converge, especially for Darlington transistors. If you need better matching than that, I suggest you average several readings, or note the exact base current for the hfe reading of the first transistor and then test subsequent transistors a few times until you get a reading at a similar base current. The unit switches off after about 15 seconds if on battery and stays on forever if powered by USB. The battery should be good for about 4000 tests between charges. Adjustable Ultrasonic Cleaner queries Once again, S ilicon C hip has inspired me, thanks to John Clarke. Before I started building the Adjustable Ultrasonic Cleaner (July-August Australia's electronics magazine 2026; siliconchip.au/Series/461), I have a few questions. Do you intend to create a kit for this or just provide the PCBs and programmed PIC? Regarding the tub, I see no mention of an enclosure/holder for it? I was thinking of 3D-printing one, but are there any considerations such as supporting it from the bottom versus the top lip that may dampen its effectiveness? Is there any preference for a round, rectangular, or square tub? Regarding the diecast box, is there any special reason why it is metal apart from the need to provide heatsinking for the Mosfets and voltage regulators? The extended shaft arrangement for the pot looks a little basic. Can I offer an STL file for a 3D-printed one? Please keep more of these projects coming, and I always look forward to the interesting and varied articles. (R. W., King Creek, NSW) ● If there is a kit, we usually mention it in the article (often at the bottom of the Parts List) and on the Online Shop page in that issue. All our kits are also listed at siliconchip.au/Shop/20 There is no kit for the Adjustable Ultrasonic Cleaner, but as usual, the PCBs and programmed PIC are available (siliconchip.au/Shop/8/7704). We can also supply the ETD29 transformer parts and some Mosfets, listed on that same web page. As you suggest, the metal box was chosen to provide heatsinking for the semiconductors. You could come up with a different arrangement with separate heatsinks in a different enclosure that’s not made of metal. Thanks for the suggestion to make a 3D-printed shaft extender. Jaycar used to sell a brass shaft extender, but it’s no longer available, so we came up with the idea of using the brass Earth connector as it is an ‘off-the-shelf’ part. A 3D-printed version would make it neater. A round or square container would be better than a rectangular one. It does not seem critical where the container support is placed. It could be supported at its top lip or via a stand at November 2026  101 C Version static bool is_leap_year(uint16_t year) { return (year % 4 == 0) && ((year % 100 != 0) || (year % 400 == 0)); } static uint8_t days_in_month(uint16_t year, uint8_t month) { static const uint8_t days[] = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }; if (month == 2 && is_leap_year(year)) return 29; return days[month - 1]; } void fix_gps_rollover(uint16_t *year, uint8_t *month, uint8_t *day) { uint32_t days = 1024 * 7; // 7168 days /* Convert current month/day to zero-based day of year */ uint32_t day_of_year = *day - 1; for (uint8_t m = 1; m < *month; m++) day_of_year += days_in_month(*year, m); day_of_year += days; /* Advance whole years */ while (day_of_year >= (is_leap_year(*year) ? 366 : 365)) { day_of_year -= is_leap_year(*year) ? 366 : 365; (*year)++; } /* Convert remaining day-of-year back to month/day */ *month = 1; while (day_of_year >= days_in_month(*year, *month)) { day_of_year -= days_in_month(*year, *month); (*month)++; } *day = day_of_year + 1; } MMBasic version FUNCTION IsLeapYear%(Y%) IsLeapYear% = (Y% MOD 4 = 0) AND ((Y% MOD 100 <> 0) OR (Y% MOD 400 = 0)) END FUNCTION FUNCTION DaysInMonth%(Y%, M%) LOCAL D% SELECT CASE M% CASE 1, 3, 5, 7, 8, 10, 12 D% = 31 CASE 4, 6, 9, 11 D% = 30 CASE 2 D% = 28 IF IsLeapYear%(Y%) THEN D% = 29 END SELECT DaysInMonth% = D% END FUNCTION SUB FixGPSRollover(Y%, M%, D%) LOCAL Days%, DayOfYear%, I%, YearDays% Days% = 1024 * 7 ‘ 7168 days ‘ Convert current month/day to zero-based day-of-year DayOfYear% = D% - 1 FOR I% = 1 TO M% - 1 DayOfYear% = DayOfYear% + DaysInMonth%(Y%, I%) NEXT I% DayOfYear% = DayOfYear% + Days% ‘ Advance whole years DO IF IsLeapYear%(Y%) THEN YearDays% = 366 ELSE YearDays% = 365 ENDIF IF DayOfYear% < YearDays% THEN EXIT DO DayOfYear% = DayOfYear% - YearDays% Y% = Y% + 1 LOOP ‘ Convert remaining day-of-year back to month/day M% = 1 DO WHILE DayOfYear% >= DaysInMonth%(Y%, M%) DayOfYear% = DayOfYear% - DaysInMonth%(Y%, M%) M% = M% + 1 LOOP GPS module 1024D% = DayOfYear% + 1 week rollover bug code END SUB 102 Silicon Chip Australia's electronics magazine the base. Our version used a small rectangular timber base that surrounded the centrally located transducer and no damping was observed. GPS module 1024-week rollover bug I’m writing to get your opinion on a problem I noticed with an EM-408 GPS module. These modules were featured in several of your early articles on GPS-controlled clocks. For example, in the March and November 2009 issues (siliconchip.au/Series/43). I designed and built a digital clock based on this module using a Micromite and a 16×2 LCD display. The Micromite extracts the date and time information from the $GPRMC record of the EM-408 output stream. Everything worked well for many years until last month I observed that the date displayed was incorrect. It was showing 23 Jan 2009. However, the time is still shown correctly. After a bit of searching, I found that this faulty date was the date string actually contained in the $GPRMC record. When I swapped the EM-408 for a VK2828U7G5LF, the date and time were displayed correctly. So for some reason the EM-408 was inserting false date information into the $GPRMC record. It puzzles me. Can you throw any light on this phenomenon? (J. H., Nathan, Qld) ● GPS modules are good for about 1024 weeks of use, which is just under 20 years. That’s usually from the date of design or manufacture, not when it was purchased. After that, the date will jump back about 20 years. This is a limitation of the GPS protocol. The EM-408 was released in 2006/2007, meaning it’s expected to be obsolete in 2026. It’s a bad design, but that’s how they decided to do it, and many GPS modules are similar. The VK2828 is a newer design, so it isn’t affected yet, but one day the same thing might happen. Such modules can still be used with software compensation that adds 1024 weeks to the date from the module. Unfortunately, that is not as easy as an exact number of years. Example C and MMBasic code to fix this problem is shown opposite. We’ve only done basic testing, but this code seems to work. continued on page 104 siliconchip.com.au MARKET CENTRE Advertise your product or services here in Silicon Chip KIT ASSEMBLY & REPAIR FOR SALE DAVE THOMPSON (the Serviceman from Silicon Chip) is available to help you with kit assembly, project troubleshooting, general electronics and custom design work. No job too small. Based in Christchurch, New Zealand, but service available Australia/NZ wide. Email dave<at>davethompson.co.nz LEDsales KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith: 0409 662 794 keith.rippon<at>gmail.com PCB PRODUCTION PCB MANUFACTURE: single to multilayer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au LEDS, BRAND NAME AND GENERIC LEDs, filament LEDs, LED drivers, heatsinks, power supplies, kits and modules, components, breadboards, hardware, magnets. Please visit www. ledsales.com.au PMD WAY offers (almost) everything for the electronics enthusiast – with full warranty, technical support and free delivery worldwide. Visit pmdway.com to get started. Micromite Explore-40 October 2024 Complete Kit SC6991: $35 siliconchip.au/Article/16677 Includes the PCB and all onboard parts. Audio Breakout board and Pico BackPack are sold separately. Issues Getting Dog-Eared? Keep your copies safe with these handy binders Order online from www.siliconchip.com.au/Shop/4 or call (02) 9939 3295. See website for overseas prices REAL VALUE A T $21.50* PLUS P&P 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 (02) 9939 3295. 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 November 2026  103 Advertising Index Altronics.................................35-42 Blackmagic Design................... 5, 9 Dave Thompson........................ 103 DigiKey Electronics..................OBC Emona Instruments.................. IBC Hare & Forbes........................10-11 Jaycar............................. IFC, 22-25 Keith Rippon Kit Assembly....... 103 LD Electronics........................... 103 LEDsales................................... 103 Microchip Technology.................. 7 Mouser Electronics....................... 3 PCBWay....................................... 57 PE Back Issues............................. 6 PMD Way................................... 103 SC RPi Pico W BackPack........... 43 Silicon Chip Back Issues........... 53 Silicon Chip Binders................ 103 Silicon Chip DCC Kits................ 65 Silicon Chip Explore-40........... 103 Silicon Chip Kits........................ 83 Silicon Chip PDFs on USB......... 82 Silicon Chip Shop.................90-91 Silicon Chip Battery Checker.... 89 The Loudspeaker Kit.com............ 8 Wagner Electronics..................... 87 GPS Nixie Clock date wraparound I built the 6-Digit Retro Nixie Clock (February & March 2015; siliconchip. au/Series/282) soon after it came out, and it has performed faultlessly until yesterday, the 14th of June, 2026. When we woke up, it was showing UTC time, not local (as happens occasionally here), but when it finally showed local time, it was displaying one hour ahead, ie, summer time. This seemed strange until I checked the date the clock displayed, which was 29/10/06, nearly 20 years ago. I immediately thought of the GPS date rollover problem, but a quick check showed that was in 2019 and the next one isn’t until 2038. To be certain it wasn’t a glitch of some sort, I switched the unit off for several hours. When switched back on, the problem was still there. So the clock believes that today is 30/10/2006, not 16/6/2026. Apart from some really weird fault with the GPS receiver, the only other thing that springs to mind is a software bug. Are there any other possibilities? I am using an EM-408 GPS module for timekeeping. (K. O., Westbury, Tas) ● Looking through our source code, all dates are handled in BCD format, so we don’t see how there can be a wraparound or overflow until the year 2100 at the earliest. We can’t 100% rule it out, but it seems very unlikely, especially since the day and month have also changed in your case. The 29th of October 2006 is exactly 1024 weeks before the 14th of June 2026. That points to the GPS receiver reporting a date one GPS epoch too early. Errata and on-sale date for the next issue iClap intelligent multi-clap switch, Circuit Notebook, June 2026: it’s better to connect the relay contacts between the mains outlet’s Active terminal and the lamp, in series with S1. Regardless, S1 must always be switched off (and ideally the circuit breaker too) before changing the lamp because RLY1 could be energised at any time. You can’t rely on RLY1 to disconnect Active from the lamp socket for safety even if RLY1 is placed in the Active circuit. Ducted Heat Transfer Controller, September 2025: in the fourth paragraph on p68, the article mentions the Jaycar HB6116 & HB6114 vented enclosures, stating that the latter is smaller than the former; it should be the opposite. Solar-Powered Lighting System, May & June 2010: the 2.2kΩ resistor shown above IC1 in the PCB overlay diagram (Fig.6) should be 22kΩ. Next Issue: the December 2026 issue is due on sale in newsagents by Monday, November 23rd. Expect postal delivery of subscription copies in Australia between November 20th and December 9th. 104 Silicon Chip Australia's electronics magazine So we suspect the GPS module is at fault. You could connect it to a USB/ serial interface and look at the date string in the RMC messages. We suspect you will find that it’s giving out the wrong date. The EM-408 is quite an old design, released in 2007, so it was likely developed in 2006. That would explain why it has wrapped around 1024 weeks later and gone back to 2006. If that’s the case, there are two possible solutions: 1. Replace the GPS module with one that gives the correct date. 2. Make a custom version of the firmware that compensates by adjusting the date/time from the module. This will be a little involved since it will need to adjust the year, month and day to add 1024 weeks. It would probably be necessary to convert the date from the GPS module into days since January 1st, 2006, or similar, then add 1024 × 7 and convert it back to a date. The code we have shown on the previous page may be helpful. Simple audio preamp wanted Can you advise me if you have ever published a design for a simple (preferably mono) preamplifier on a relatively small PCB that can run from a single DC voltage rail? I restore valve radios at a serious hobby level, doing many for other people, and I often add a small preamp so the radios will produce adequate output when fed with an audio signal from (say) an MP3 player, which produces an audio output level is significantly lower than the level from the radio’s detector. This means that the volume control of the radio has to be turned up really high when being fed with such a signal. Until recently, I had been using the Champ preamp. While I am well aware of its design deficiencies, it worked fine. However, I have just become aware that Jaycar is no longer stocking this preamp, so I am looking for a suitable alternative. (P. W., Pukekohe, NZ) ● The 2013 Champion preamp was designed to replace the ancient Champ and Prechamp designs. Jaycar has a complete kit (Cat KC5519), while Altronics has a preamp-only kit available (Cat K6044). 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