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MAY 2026 ISSN 1030-2662 05 9 771030 266001 The VERY BEST DIY Projects! $14 00* NZ $14 90 INC GST INC GST AMPLIFIER CLIPPING INDICATOR protect your loudspeakers from being overdriven Analog Computers how they differ from digital computers, and are they making a comeback? microDCC Decoder our smallest decoder yet Despite its size, it has two 100mA function outputs and sound output Rosehill Gard e 3 – 4 June 2 ns Event Centre 026, see pag e 40 Contents Vol.39, No.05 May 2026 16 Analog Computers, Part 1 Nowadays computing is pretty much all digital, so have we moved on from analog computers; or might they come back? We look at what makes analog computers unique, with historical and modern day examples. By Dr David Maddison, VK3DSM Technology feature Analog Computers Page 16 40 Electronex 2026 The Electronex exhibition is back in Sydney this year, to be held at Rosehill Gardens Event Centre on the 3rd and 4th of June. By Various Authors Trade exhibition showcase 76 Power Electronics, Part 7 In this series of articles, we explore the principles of power electronics. This month, we cover resonant converters and soft switching, and how switching losses can be a greater problem at higher frequencies. By Andrew Levido Electronic design Page 62: compact and simple ¬C Meter 82 Installing a CB Radio in your Car Here’s how to neatly fit your own CB radio in a car, which can be very useful when driving on country roads. By Julian Edgar Automotive / radio feature 90 BrisbaneSilicon ELM11 Board The ELM11 is an affordable development board that uses the LUA programming language and is designed in Australia. Review by Tim Blythman Microcontroller development board 30 Power Amp Clipping Indicator Protect your loudspeakers from being overdriven and possibly destroyed with our Clipping Indicator. It can reduce the signal level applied to an amplifier, protecting the speakers, and can be built-in or standalone. By John Clarke Audio project 62 Simple LC Meter Using just 20 parts, this tiny LC meter can measure inductances from <10nH to around 100mH and capacitances from <10pF to about 1μF. It’s powered from a single AA cell and is housed in a 3D-printed case. By Andrew Woodfield Test & measurement project 69 WiFi Alarm Monitor This project is ideal for checking up on the elderly. It monitors both an alarm condition (like a burglar alarm going off) and daily activity. It can then send a remote alert to a device like a phone or an email address. By Kenneth Horton Monitoring project 84 μDCC Decoder Our previous DCC Decoder was a small design at 23 × 14mm, but we thought we could one-up it and make it even smaller. This microDCC (μDCC) Decoder measures 18 × 12mm and even has sound output. Part 7 by Tim Blythman Model train project Page 69 WiFi Alarm Monitor 2 Editorial Viewpoint 4 Mailbag 89 Subscriptions 94 Circuit Notebook 97 Online Shop 98 Serviceman’s Log 104 Vintage Radio 109 Ask Silicon Chip 111 Market Centre 112 Advertising Index 1. SOT-223 adaptor for VAS transistors 2. Automatic level crossing controller 3. Battery charger using a relay and lamp Airzone 6552A Concert Star by Associate Professor Graham Parslow 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.) 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Since COVID-19, we’ve absorbed significant increases in paper, printing and distribution costs. Like many others, we were told these were temporary ‘supply constraints’, but the reality is those prices never came back down. Also, some advertisers reduced their marketing budgets over the last few years as a ‘temporary’ measure, but those cuts have largely remained. We are now facing rising interest rates, sudden fuel surcharges and further postage increases, including letter delivery, which directly affects magazine mailing. We’ve kept increases modest for as long as we could, but ongoing cost rises now have to be reflected in our pricing. From the June issue, the cover price will increase to $15. Subscription prices will increase by approximately 7.5% from June 1st. This allows us to maintain the quality and depth of content you expect from Silicon Chip. Our aim, as always, is to keep Silicon Chip viable for the long term. If you want to renew at the current lower rates, you can do so before the end of May. Even with the increase, subscriptions remain significantly better value than buying individual issues. Twelve issues at the cover price would cost $180, while a subscription is $145 including delivery. Online subscriptions will increase only slightly, to $105 for one year, reflecting less impact from printing and mailing cost increases. That’s still only $8.75 per issue. And the individual price for the online issue will remain at $10 each. By the way, you can extend your subscription to take advantage of the currently lower price even if it won’t expire for a while yet. Practical Electronics PDFs now available Now for some good news. You may be aware that we took over the UK magazine Practical Electronics in mid-2024. We are now offering PDF back issues covering 24 years (288 issues from 2000–2023) for $165 as a download or $180 + P&P on a USB drive. Silicon Chip subscribers receive a 10% discount. While some content overlaps with Silicon Chip, Practical Electronics also features strong original material, including columns such as Circuit Surgery, Audio Out, Max’s Cool Beans and Teach-In, covering electronics theory, audio, microcontrollers and in-depth tutorials, respectively. We expect that Silicon Chip readers will find these valuable. If space permits, we’ll include sample articles in future issues so our readers can get an idea of what those columns entail. You can order the PDFs in either form from the top of the page at www.siliconchip.au/Shop/3 by Nicholas Vinen Subscription Prices, effective 01/06/2026 New Prices Print Print+Online Print Print+Online Print Online 6-month $77.50 $87.50 $95 $105 $115 $55 12-month $145 $165 $180 $200 $220 $105 24-month $270 $305 $335 $370 $410 $200 New Zealand RoW Australia Prices from June 1st, 2026; all prices are listed in Australian dollars (AUD). RoW = Rest of World 1 Huntingwood Dr, Huntingwood NSW 2148 54 Park St, Sydney NSW 2000 2 Silicon Chip Cover background: https://unsplash.com/photos/white-clouds-on-blue-sky-UiiHVEyxtyA Australia's electronics magazine siliconchip.com.au Discover Design Develop mouser.com 412S 654-CL90555DT32 673-100B-1003XT 340103211B 654-10-504637-008 A17251-09 11350 CB5347-000 RSPST070856 Order - with - Confidence 03 9253 9999 | australia<at>mouser.com 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”. Classic mains power indicators I was interested to see the Mains Power LED Indicator in the February 2026 issue (siliconchip.au/Article/19655). I have a similar indicator in my workshop with a story attached to it. I wanted a wide-angle, long-lasting indicator lamp to remind me if I had forgotten to switch off the main workshop power. Some years ago, I visited Alcatraz (the historic prison island near San Francisco) and was surprised to see a gigantic, very aged-looking neon lamp on an old fuse and switchboard that was still glowing, probably since the 1930s. I knew that most American panel lamps with these sorts having clear or coloured glass lenses were made by Dialco. Later, when I was looking on eBay for a Dialco glass-lens panel lamp for another project, I stumbled across one of the exact same gigantic neon indicator lamps as the one I saw at Alcatraz. So I put it in a painted and labelled diecast box with a panel line IEC connector to feed it with an extension cord from the main power feed board and hung it on the wall (see the attached photo). It reminds me not to spend too much time in the workshop, too! Dr Hugo Holden, Buddina, Qld. Sourcing good-quality axial electrolytic caps I have not yet had to replace the main power supply filter caps in my Tektronix 2465B oscilloscopes, featured in the Vintage Electronics column last month. However, I did some research. It is a little difficult to find axial capacitors of suitable size, capacitance and voltage values these days. A large neon indicator lamp put in a diecast box to imitate the look of the lamps found in Alcatraz. 4 Silicon Chip I eventually discovered some amazing suitable replacements that are available from AliExpress. I bought some for evaluation in my workshop, and they passed with flying colours, with extremely low leakage values. They are genuine parts (not fakes), likely left over from an automotive manufacturing contract. They are EPCOS Sikorel military-specification style parts with astonishingly high temperature and high pulse current ratings (they can even be shorted without damage, not that you should do it!). I have attached a photo below. They are excellent parts, and I hardly ever say that about electrolytic capacitors. It is worth looking up the specifications of these Sikorel capacitors, which come in many values and sizes; there are many on AliExpress for sale. I bought enough of these to replace the original parts in my vintage oscilloscope, if or when they fail. Some of the parts available include: • AliExpress 1005009581483411 (270μF 200V; what I bought) • AliExpress 1005009559895645 (10μF 100V) • AliExpress 1005010449425160 (680μF 75V) • AliExpress 1005010433682158 (470μF 75V) • AliExpress 1005007864314700 (680/1000/1800μF 40V) • AliExpress 1005010745748467 (470/1000μF 35V) Dr Hugo Holden, Buddina, Qld. Interesting method of replacing SMDs I was interested to read David Coggins letter on page 4 of the March 2026 issue. His experiences largely mirrored These EPCOS Sikorel electrolytic capacitors have extremely high temperature and current ratings. Australia's electronics magazine siliconchip.com.au Where Australia’s Electronics Future Comes to Life Explore breakthrough technologies, design solutions and manufacturing advances for electronic products. SMCBA CONFERENCE Engage with Australia’s industry leaders and experts at the SMCBA Electronics Design and Manufacture Conference. Details at www.smcba.asn.au In Association with Supporting Publication Organised by Above: to remove the PIC on one of Silicon Chip’s RGB LED Analog Clock kits, Richard Verrall used a small cut-off disc from an angle grinder to sever the pins. The remaining solder was then easily removed. Right: the voltage (cyan) and current (yellow) waveforms using a current clamp and the HV Isolating Probe. mine. I bought two RGB LED Analog Clock kits, one having the GPS module and the other with WiFi capability. The first kit functioned as expected. I then assembled the second clock kit, but got a very garbled light display. So I ordered another PIC and found a satisfactory way to remove the existing unit by using a very small cut-off disc to sever the device’s legs. It looks like a mess, but surprisingly, the remains of the legs could be desoldered and removed. The board then cleaned up better than expected. I ordered some new programmed PICs, hoping they might resolve the impasse! Richard Verrall, Taroona, Tas. Comment: it isn’t hard to remove these chips using a lowcost hot air rework station. Still, it’s good to know there’s another method. We’ve had a few people now report that their problems with the Clock kit went away after replacing the PIC. So it seems increasingly likely that a bad batch of PICs made its way into the kits. We always verify the flash contents after programming them, so it should not be a problem in their programming. Reactive current fools master/slave power board Silicon Chip readers may be interested in this problem we had with a new LG OLED TV. We have been using a master/slave power board with our TV to turn off all the accessories (DVD, sound bar, Xbox etc) to save standby power when we are not using the TV. When we replaced the TV with an LG OLED type, the master/slave power board stopped working, remaining on all the time. I used one of those plug-in power meters to see what was going on. It showed the TV was drawing 0.22A in standby but only using 0.3W! No wonder the power board was confused. When switched on, it used around 0.7A and 150190W depending on the picture brightness. I had a look at the voltage and current waveforms on an oscilloscope (see the photo at upper right) using a current clamp and a High Voltage Isolating Probe (January 2015 issue; siliconchip.au/Article/8244). Sure enough, the current was a sinewave close to 90° out of phase with the voltage. It is a stepped sinewave with about 19 steps per cycle, presumably being generated by the power factor correction (PFC) circuit in the TV’s switch-mode power supply, but I was surprised it was so high at 52VA of reactive voltamps in standby. 6 Silicon Chip I remembered I had the USB Sensing Mains Switch project (January 2009; siliconchip.au/Article/1271) around somewhere. After a long search, I found it and substituted it for the master/slave power board. I used one of the USB outlets on the TV to trigger it. It worked a treat and reduced my standby power from 19W to 1.5W. The flat tops on the mains voltage in the scope grab are real! They are not from overloading my probe. Mike Hammer, Mordialloc, Vic. Keep wires straight for surge protection! Well done to Ian Ashford for presenting the Solar Panel Protector and Optimiser project in the March 2026 issue (siliconchip.au/Article/19824). I am sure it will find many uses in domestic and alternative supply installations. However, I would like to point out something that surprised me when looking at the pictures of the installation. All the Earthing conductors were wound into coils. I teach electrotechnology to electrical apprentices at TAFE and sadly, this habit has been passed down from old-timers to the current-day apprentices, and I have to correct them on it. Referring to Appendix F (Surge protection devices in AS/NZS3000), Clause F1.2.5 states: Conductors used to connect a surge protection device to both the line, via the overcurrent protective device, and to the main earthing or neutral conductor should be consistent with the current rating of the backup fuse or circuit breaker but should be not less than 6mm2, be as short and direct as possible and with no loops. The idea of surge protection as outlined in Ian’s article is to shunt the surge current to Earth via the lowest impedance path possible. Placing extra turns in the Earth conductors makes them become inductors, albeit of a very small value. This small inductance can still have a very high initial impedance due to the extremely fast rise time of the surge voltage waveform. Lenz’s law then comes into play. This fast rise time coupled with the massive amount of current will create a huge amount of magnetic flux. Induced back-EMF is proportional to the number of turns in the coil multiplied by the change in flux value divided by the time it takes for that flux to change. This back-EMF could make the Earth conductor appear as an open circuit initially. This would then defeat the purpose of installing surge Australia's electronics magazine siliconchip.com.au Introducing ATEM Mini The compact television studio that lets you create presentation videos and live streams! Blackmagic Design is a leader in video for the television industry, and now you can create your own streaming videos with ATEM Mini. Simply connect HDMI cameras, computers or even microphones. Then push the buttons on the panel to switch video sources just like a professional broadcaster! You can even add titles, picture in picture overlays and mix audio! Then live stream to Zoom, Teams or YouTube! Live Stream Training and Conferences Create Training and Educational Videos Monitor all Video Inputs! ATEM Mini’s includes everything you need. All the buttons are positioned on the front panel so it’s very easy to learn. There are 4 HDMI video inputs for connecting cameras and computers, plus a USB output that looks like a webcam so you can connect to Zoom or Skype. ATEM Software Control for Mac and PC is also included, which allows access to more advanced “broadcast” features! With so many cameras, computers and effects, things can get busy fast! The ATEM Mini features a “multi-view” that lets you see all cameras, titles and program, plus streaming and recording status all on a single TV or monitor. There are even tally indicators to show when a camera is on air! Only ATEM Mini is a true professional television studio in a small compact design! All models have built in hardware streaming engine for live streaming via its ethernet connection. This means you can live stream to YouTube, Facebook and Teams in much better quality and with perfectly smooth motion. You can even connect a hard disk or flash storage to the USB connection and record your stream for upload later! Use Professional Video Effects ATEM Mini is really a professional broadcast switcher used by television stations. This means it has professional effects such as a DVE for picture in picture effects commonly used for commentating over a computer slide show. There are titles for presenter names, wipe effects for transitioning between sources and a green screen keyer for replacing backgrounds with graphics. www.blackmagicdesign.com/au ATEM Mini Pro..........$469 ATEM Software Control..........FREE Learn More! protection. Once again, it is a great project, but it is good practice to keep the wiring short and direct. Geoff Coppa, Toormina, NSW. Computer evolution over the last 30 years It was interesting to see the photo of the IBM XT computer on page 26 of the February 2026 issue of Silicon Chip. That was my first PC, after having an Apple IIe, Commodore 64 & 128, Amstrad 64 & 128, Amiga 500, Macintosh etc, most of which I picked up at tip shops and op shops. I got the IBM XT at the local tip shop. It was missing a video card. I also picked up some other junk: monitors, video cards and the like. After trying different video cards and a couple of monitors, I got the XT working. It had a 10MB MFM hard drive, two 360-kilobyte floppy drives and a green monochrome monitor. It was running DOS 3.3; I used XTGold as the file manager. I still have that PC sitting on a shelf in my shed, unused for decades. After that I had a 286, 386 and then 486 with DOS 6.22 and Windows 3.1. I also had several Macintoshes: the P1, P2, P3 and P4 with CRT monitors, 4:3 LCD monitors and then 16:9 LCD monitors. Then came Windows 95, 98, 98SE, 2000 and XP. Most of that hardware came from tip shops and a computer shop that I was collecting the ‘junk’ from – old hardware that customers no longer needed when they upgraded. Then I switched to laptops instead of desktop machines, with dual-core i3s, i5s, i7s running Windows 7, 10, 11 and now Linux. Advances in technology lead to unusable hardware; with Windows 11 not supported on so many devices, we can expect to see many more people switching to Linux with the end of support for Windows 10. Fortunately, Linux runs well on old dual-core devices, so that may save a lot of old hardware from the scrap heap. Bruce Pierson, Dundathu, Qld. Comment: Windows 11 updates have caused a lot of problems lately, making staying on Windows 10 feel like dodging a bullet! There’s nothing wrong with many of those “obsolete” computers except that Microsoft has decided not to support them anymore. Flashing Mains LED Indicator suggestion Thanks for the Mains Power LED Indicator project (February 2026; siliconchip.au/Article/19655); I’ve built similar circuits without a zener diode. I recently built a mains-­ powered, DIAC-based LED flasher for my pool pump setup, as I often forget to switch the pool pump timer/electrics back to normal from pause mode after pool maintenance. When I read your article, I thought your design had the potential for an updated version, with an onboard slide switch to choose between always-on or flash mode. Ciril Kosorok, Mount Druitt, NSW. Transistor-assisted ignition circuit improvements I refer to your Serviceman’s Log entry in November 2025 on a transistor-assisted ignition unit repair by Bruce Pierson (siliconchip.au/Article/19230). I recall building several of them ‘back in the day’; in fact, I still run one on a 1950 Rolls Royce Silver Dawn. A couple of simple modifications to the original circuit to improve performance and efficiency may be of some interest to others. My revised circuit is shown overleaf. 8 Silicon Chip Australia's electronics magazine siliconchip.com.au A revised circuit of the Transistor Ignition from Electronics Australia December 1979. The changes include an added BC548 transistor, 10W resistor and a 27nF capacitor between the collector and emitter of Q4. Firstly, adding a transistor (BC548) from the base to the emitter of the BUX80, in conjunction with a 10W resistor from the emitter of Q2 to ground, forces the main switching transistor to switch off much faster. It does this by pulling the base to the emitter instead of simply removing the base drive to the BUX80, giving a quicker switch-off time, therefore producing a faster and more vigorous spark. The original 220nF points capacitor value is a compromise. Too low and all the stored coil energy makes a mini arc welder across the points. Too high means too much energy being absorbed by the capacitor with little remaining to create a healthy spark. When a transistor is doing the hard work of switching, we can get away with a significantly smaller value capacitor in this position. A value of 27nF results in a significantly more energetic spark and with a faster rise time. A faster rise time means less time for the spark to be potentially bled away from a dirty/fouled spark plug. More spark energy has to be a good thing! I found that removing one of the three 2.7W resistors supplying base current to the BUX80 still enabled that transistor to saturate to around 0.25V. J. B. Upper Caboolture, Qld. Comment: that design was from a long time ago (47 years!). Our latest ignition systems utilise an IGBT as the switching element. As you point out, the points capacitor really needs to be selected for the best compromise between wear on the points and spark energy. The ideal value depends on the ignition coil, mechanical arrangement for the points and engine type (low-revving, high-­ revving etc). Lilienfeld’s patents in the 1920s and 1930s, plus Heil in 1934) were theoretical or non-functional. However, there is another possibility, often called the “lost transistor”: the Adams Crystal Amplifier from 1933, created by a 13-year-old New Zealander, Robert Adams. He used crystals like chalcopyrite and iron pyrite to create this device. It was essentially like a cat’s whisker diode (which was in common use at the time) but with an additional point contact added. It demonstrated the potential of solid-state amplification. He regarded his invention as “obvious” and thus unpatentable. Unlike the Bell Labs device, it was not properly documented, published in scientific journals, or patented. SC Dr David Maddison, Toorak, Vic. Who really invented the transistor? The Bell Labs point-contact transistor, developed by Bardeen, Brattain and Shockley in 1947, is widely recognised as the first working transistor. Earlier attempts (eg, 10 Silicon Chip This may be the first transistor, invented by a 13-yearold New Zealand boy in 1933. 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T oday, what most people think of as a computer is a digital computer, like a laptop or smartphone. However, digital computers weren’t the first and aren’t the only kinds of computers. The first electronic digital computer was built in 1946. Called ENIAC, it filled a room – see Fig.1. One of its jobs was to compute artillery trajectories. The Moore School of Electrical Engineering at the University of Pennsylvania developed an alternative: a simple analog differential analyser, a type of mechanical analog computer (Fig.2). It performed the same task with gears and shafts in a much smaller space, foreshadowing a rivalry that has lasted nearly 100 years. Some analog computers are very ancient indeed. Originally, all analog computers were mechanical, but in the 1940s, electronic analog computers were developed. They are easier to develop than mechanical designs and more reliable. They have some advantages compared to digital computers. Unlike digital computers, which represent information using discrete 16 Silicon Chip binary states (0 or 1), or quantum computers, which use discrete qubits that can be in a superposition of the 0 and 1 states, an analog computer can represent and process a continuum of values, using something like a voltage or current. That gives it an almost infinite number of distinguishable states within the physical range. Analog computers started to become obsolete in the late 1950s with the rise of transistors and early digital machines, accelerating through the 1970s as microprocessors like the Intel 4004 (1971) made digital computers scalable and affordable. However, analog computers remained in some niches (eg, flight simulators) into the 1980s. By the 1970s, mechanical and electronic analog computers had become largely obsolete, replaced by faster, more precise digital systems. However, they are now making a comeback in various forms, where their ability to electronically represent a continuum can bypass digital computer bottlenecks. Australia's electronics magazine This article will concentrate on describing traditional analog computers, their uses, and covering their history. A follow-up article next month will look at the current and future uses of analog computers and state-of-theart technology. Differences between analog and digital computers An electronic analog computer cannot do everything a digital computer can do, but it can excel in certain realtime simulations of physical systems, where it can have superior speed and efficiency. Because an analog computer deals with continuous values, its accuracy and repeatability are inferior to a digital computer. Analog computers typically have a calculation error in the 0.1-1% range. Traditional electronic analog computers were programmed by physically rewiring a patch panel – see Fig.3. This same method was used on some of the earliest digital computers, such as ENIAC, the Harvard Mark I and the siliconchip.com.au Colossus computer for cryptographic key settings. In modern analog and mixed-signal systems, the physical patch panel has largely been replaced by digital configuration interfaces (SPI, I²C, USB etc) that program field-­programmable analog arrays (FPAAs), memristor crossbars, floating-gate arrays or switched-capacitor circuits, making it easier to change their configuration. Where analog computers excel Traditional analog computing excels at real-time simulations of continuous physical phenomena, such as the flight dynamics of aircraft. More recently, its ability to map physical variables directly onto continuously variable electrical signals (voltages, currents, or resistances) has made analog hardware extremely attractive for mimicking biological neural networks. They can perform the massive matrix-vector multiplications required in AI pattern recognition and sensory processing with far greater energy efficiency than conventional digital chips. This dramatic power consumption advantage, often by a factor of 1001000 times for similar workloads, is the primary driver behind the current resurgence of interest in analog and analog-inspired computing techniques. Figs.1: the ENIAC electronic digital computer circa 1947-1955. Like the one shown in Fig.2, it could compute artillery trajectories, but the analog computer was smaller and more efficient at the time. Source: https://penntoday.upenn. edu/news/worlds-first-general-purpose-computer-turns-75 Where digital computers excel Digital computing excels in precision, repeatability and accuracy, as intermediate and final values are represented by precise mathematical values, not analog properties, which cannot be precisely or reproducibly represented. Also, digital computers can run a huge array of software from word processing to video editors to databases and everything else imaginable; analog computers usually perform much more specific tasks. Digital computers can also store vast amounts of data and programs and with results reproducible between different computers, and are not subject to subtle hardware variations between platforms. The digital computer is a practical realisation of Alan Turing’s Universal Turing Machine (UTM) — a theoretical device capable of computing any function that is algorithmically computable. siliconchip.com.au Fig.2: a mechanical analog computer circa 1942-1945. Fig.3: a Comdyna GP-6 (user manual: siliconchip.au/link/acag) made for educational purposes. Its prominent patch panel is set up to solve the simple equation x’’ + x’ = 0 representing a certain case of pure viscous damping. Source: www.glennsmuseum.com Australia's electronics magazine May 2026  17 In contrast, real-world analog computers built in the 20th century were not universal in the Turing sense because they could only efficiently solve specific classes of problems (mainly differential equations) and lacked the ability to simulate arbitrary computation without exponential growth in hardware. However, Claude Shannon proved in 1941 that a theoretical model he called the General Purpose Analog Computer (GPAC), built from ideal integrators, adders, multipliers and constant units, is equivalent in computational power to a Universal Turing Machine and can therefore compute any computable real function (to arbitrary precision, given unlimited time and perfect components). While Shannon proved that a theoretically ideal GPAC is as powerful as a UTM, no physical GPAC can ever be implemented exactly because real electronics cannot provide infinite precision, infinite range or perfect components, making true analog universality practically unattainable. Despite this, special-purpose analog computers remain extremely useful. What analog computers do Traditional analog computers of the past could emulate physical systems, such as: • Aerospace and flight dynamics to model aerodynamic forces, pitch, roll, yaw and jet engine inlet control, such as on the SR-71, which used a hydraulic analog computer. • Aquifer simulation. • Astronomical or planetary motion Fig.4: a reproduction of the back of the Antikythera mechanism. Source: https://w.wiki/HRct 18 Silicon Chip (eg, the Antikythera mechanism and many later planetariums). • Automotive automatic transmissions; for more on this, see our article on “Fluid logic, Fluidics and Microfluidics” in August 2019 (siliconchip. au/Article/11762). • Ballistics and trajectory analysis. • Chemical reaction simulation. • Convective flow simulation. • Damped mechanical system simulation (eg, vehicle suspensions). • Economic modelling (as in the MONIAC hydraulic computer). • Electronic circuits. • Flight simulation. • Fluid dynamics simulation. • Heat transfer simulation. • Hydraulic and fluid networks, such as the flow of fluids through complex pipe networks in chemical plants, water supplies or sewerage systems. • Medical monitoring. • Nuclear reactor kinetics; modelling thermal and neutron flux. • Oscillating systems like massspring-dampers. • Power-grid analysis. • Radioactive decay simulation. • Tide prediction. • Temperature and industrial process control. Analog computer history The history of analog computers can be divided into two main eras, the ‘classic’ and ‘modern’ eras. The classic era is: • Up until the 1940s, mechanical and electro-mechanical computers dominated. They were expensive and slow to configure. Fig.5: a reproduction of the front of the Antikythera mechanism. Source: https://w.wiki/HRcs Australia's electronics magazine • During the 1940s and 1950s, valves and electronic analog computers appeared and began to dominate. The K2-W valve op amp module was introduced in 1953. • During the 1960s and 1970s, transistorised op-amp based computers became inexpensive and were used in engineering education and industry. This was the peak of analog computing in the classic era. • From the 70s onward, digital computers dominated, with analog computers continuing only in niche areas. In the modern ‘revival’ era, from around 2020 onward, the focus of analog computers is on energy-efficient AI inference engines and AI matrix-vector multiplications. Such analog or mixed-signal chips are being produced by companies like Imec (from 2020), Mythic (from 2021), Lightmatter (from 2022), Aspinity & SynSense (from 2023), ACCEL & IBM (from 2024), Anabrid (from 2025), as well as Encharge, Microsoft and Peking University. Mechanical analog computers Here is a list of some of the important mechanical analog computers: Antikythera mechanism (200BCE) The first known specialised mechanical analog computer was the Antikythera mechanism (Figs.4 & 5) made between 200BCE and 80BCE and discovered at the bottom of the Mediterranean Sea in 1901. It is a complex geared mechanism (the details of which can be seen at https://w. wiki/HRcu) that was used to predict Fig.6: Lord Kelvin’s tide predicting machine. Source: https://w.wiki/HRcv siliconchip.com.au Fig.7: a replica of the Difference Engine located at the Computer History Museum in Mountain View, California. The first complete one is located in London’s Science Museum. Source: www.flickr.com/photos/jitze1942/4305143894/ Fig.8: a Norden Bombsight. Source: https://w.wiki/HRcw astronomical positions and eclipses decades in advance. A neat interactive example of a partial reconstruction can be viewed at siliconchip.au/link/acaq It is a remarkable achievement of science and engineering that has been subject to intense study ever since its discovery. With X-ray tomography in 2005, it became possible to read its inscriptions and determine other details. It is estimated to have had at least 37 gears. An Australian YouTuber went through much of the manufacturing process using the same tools and materials the ancients would have had (see https://siliconchip.au/link/aca0). mechanical integrators (six in the initial version) driven by electric motors, shafts and gears to solve complex differential equations. It was originally built to model power transmission networks, but it quickly proved invaluable for problems in physics, ballistics, seismology and more, dramatically reducing calculation times from months to hours. Slide rule (1622) English clergyman William Oughtred invented the slide rule around 1622, shortly after John Napier introduced the logarithms on which it was based, in 1614. Slide rules were in use until around 1972, when they were replaced by calculators. Planimeter (1814, 1854) A planimeter is a form of specialised mechanical analog computer for measuring areas on a map or plan. It is a continuous mechanical integrator, hence an analog computer. A tracer is moved around the boundary enclosing an area, and the area is computed. siliconchip.com.au The first known planimeter was invented in 1814 by J. M. Hermann; the most popular design, still in use today, was invented by Jacob Amsler in 1854. The Difference Engine (1822) Charles Babbage completed his Difference Engine 0, a mechanical computer to produce mathematical tables, in 1822. This and Babbage’s subsequent work were brilliant, but suffered from enormous mechanical complexity and funding problems. Some of his designs were only completed in recent years (see Fig.7). Tide predictor (1872) Lord Kelvin developed a tide predicting analog computer (Fig.6). Machines based on this design and built by Arthur Doodson are credited with the accurate tide predictions that were vital for the D-Day Normandy landings in 1944. Differential Analyzer (1931) American engineer Vannevar Bush, along with Harold Hazen, unveiled their groundbreaking Differential Analyzer at MIT in 1931. It was a massive mechanical analog computer, often regarded as one of the first advanced computing devices of the modern era. It was a room-sized machine using interconnected wheel-and-disc Australia's electronics magazine Norden bombsight (1931) The Norden Mark XV bombsight (Fig.8) was a mechanical analog computer used during WW2 by the USAAF and US Navy, and into the Korean and Vietnam wars. Its purpose was to calculate when to drop bombs to hit a target on the ground. It was one of the most expensive programs of WW2, costing about half that of the Manhattan Project. E6-B flight computer (1940) This circular slide rule was used for flight planning. It has been replaced by electronic devices today, but is still in use for flight training, in aviation exams and for backup purposes in case electronic devices fail. Electronic and hydraulic analog computers We will now look at some significant early analog computers. Some hydraulic computers will be included among May 2026  19 Table 1: equivalent hydraulic and electrical concepts Concept Electrical Hydraulic Voltage Pressure Current Flow rate Electric charge Fluid quantity Path for ‘current’ flow Wire Pipe Impedance Resistor Constriction in pipe Energy storage Capacitor Bladder on diaphragm Inertia Inductor Turbine/paddle wheel Current flows in one direction Diode One-way valve Signal amplification Transistor Pressure-actuated valve Constant source Voltage or current source Pump w/ or w/o feedback control the electronic ones, as they operate on analogous principles – see Table 1. solving inhomogeneous differential equations. AC Network Analyzer (1929) This was an electronic or electromechanical analog computer first built by MIT’s Harold Locke Hazen under the leadership of Vannevar Bush. It was designed to study large-grid AC power systems and complex power flows in real time. The computer included components like phase-shifting transformers, inductors/gyrators, variable resistors, capacitors and adjustable loads. It was essentially a scale model of a large grid electrical system. It was programmed by physically wiring circuits on patch panels and reading results with meters. This type of machine was used extensively from 1929 to the 1960s. To reduce the size of transformers, these machines were run at a much higher frequency than the 50/60Hz of real-world networks. It was a special-purpose analog computer and a predecessor of the later general-purpose op-amp-based electronic analog computers of the 1950s. It does not seem to be regarded as an electronic analog computer by most commentators, but this author thinks it is. It is not to be confused with the 1931 Differential Analyzer, also built under Bush’s influence. V-2 Guidance Computer (1941) Despite the AC Network Analyzer above, the first generally-accepted electronic analog computer is considered to be the German Mischgerät V-2 guidance computer designed by Helmut Hölzer, used for rocket guidance. It was a single-purpose computer comprising resistors, capacitors and valve amplifiers. It differentiated voltages from yaw, roll and pitch gyroscopes to sense the rocket’s divergence from the original orientation of the gyroscopes, deriving the rate of divergence. This was converted to correcting voltages that controlled servos for the steering vanes located in the rocket exhaust. It was a much cheaper, lighter and better-performing solution than competing methods. It did not use op amps, but influenced later US analog computers, as the technology and Hölzer himself were brought to America after the war under Operation Paperclip. Water Integrator (1936) The Water Integrator (Fig.9) was a hydraulic computer invented by Russian Vladimir Lukyanov; versions of such hydraulic computers were in use in the USSR until the 1980s. In the 1930s, the original machine was the only one in the USSR capable of 20 Silicon Chip M9 Gun Director (1943) Bell Labs’ M9 Gun Director was a specialised electronic analog computer developed in the USA. It worked with the SCR-854 radar, which provided real-time range and direction data. It solved trigonometric equations, computed firing solutions and then transmitted aiming data such as azimuth, elevation and fusing time directly to gun servo motors. Apart from target speed, direction and range, it took into account wind, Australia's electronics magazine Fig.9: a version of the 1-IGL-1-3 Water Integrator hydraulic analog computer. Source: Polymus – siliconchip.au/ link/acar air pressure, shell velocity and gun parallax. It achieved a high success rate in England against German V-1 flying bombs and German aircraft, reducing the number of shells needed to shoot down a target from thousands to around 100. The M9 was the first electronic analog computer that contained circuits fulfilling the function of operational amplifiers, the foundation of later electronic analog computers, but which had not yet been named as such (see the PDF at siliconchip.au/link/aca1). The M9 laid the foundation for future integrated radar and fire control computers, including defensive weapons like the Phalanx CIWS still in use today, including by Australia. Project Cyclone (1946) A family of computers was developed by Reeves Instrument Corporation for the US Navy – see Fig.10. More than 60 REAC (Reeves Electronic Analog Computer) machines were built and placed in various institutions. Seven models were produced between 1947 and 1965. This family of computers is credited with proving that there was a viable commercial market for computers. ANACOM (1946, 1948) The Westinghouse ANACOM solved problems in grid-scale power systems, such as lightning surges on transmission lines, plus mechanical design problems, oil flow and many others (see Fig.11). It was in use until 1991. It was under constant development and, by the 1980s, it was under the control of a digital computer to set up the initial starting conditions for siliconchip.com.au Fig.10: a 1965 sales brochure for the REAC 600 from Reeves. Source: https://archive.org/details/TNM_REAC_600_ computer_system_-_Reeves_1965_20180302_0183/page/n1 problems being solved. It was probably the longest-lasting conventional analog computer used into the digital age. (like Philbrick’s K2-W) became widely used, and more advanced machines took over. model of the computer shown in the image; it may have been a REAC 100, released in 1947. The REAC 100 had 18 op amps, 10 integrators, 10 summers, 10 inverters, 25 potentiometers and five servo-multipliers. GEDA (1947) REAC (1949) The Goodyear Electronic DifferREAC (see the lead photo) was an ential Analyzer was developed for analog computer at Lewis Flight Prothe Goodyear Aircraft Corporation to pulsion Laboratory (now the John MONIAC (1949) solve differential equations for missile H. Glenn Research Center), in Ohio. The MONIAC was a hydraulic comguidance simulations. It was released NASA did not clearly identify the puter that used water and fluid logic commercially in 1949. instead of electricity and elecGEDA used valve-based tronic components for its calhigh-gain DC amplifiers staculations. It was invented by bilised by a unique commuNew Zealander Bill Phillips. tator system (a rotary switch Its purpose was to model the that periodically rebalanced national economic processes amplifier inputs to reduce of the United Kingdom. We drift), similar to the system described it in the August used in modern ‘chopper 2019 issue, on page 21. stabilised’ op amps. GEDA systems typically had 20-85 RCA Typhoon (1951-1952) amplifiers configured as inteThe RCA-designed Project grators, summers, multipliers Typhoon was one of the largetc, via patch panels. est electronic analog computThey were used for missile ers ever built (see Fig.14). It trajectory simulation, flight was designed for the US Navy dynamics, control systems to be used in solving complex and even early war-gaming. differential equations for the They were superseded by the Fig.11: the Westinghouse ANACOM (ANAlog COMputer). development of ships, submamid-1950s as true op amps rines, aircraft and missiles. It Source: www.researchgate.net/figure/fig1_220494419 siliconchip.com.au Australia's electronics magazine May 2026  21 Operational amplifiers An operational amplifier (op amp) is an extremely high-gain differential-voltagecontrolled amplifier. When negative feedback is added, typically via a few resistors and capacitors, it can be made to perform addition, subtraction, integration, voltage inversion or other mathematical operations with almost zero error. The op amp is the workhorse of the analog computer, with two inputs (+ and −) and one output. Its name comes from its original use, performing mathematical operations in electronic analog computers, but now it has many other uses. It was the basic computing element of all electronic analog computers of the 1950s to the 1970s. The term operational amplifier was coined in 1947 by John Ragazzini, but the first practical commercially available op amp was the Philbrick GAP/R K2-W, released in 1953 (Fig.12). The first truly ‘modern’ op amp was the μA741 IC, released in 1968 and still in production (see Fig.13). Other classic op amps that came later include the TL071/2/4, LM324/358, NE5532/4, LM833 and OP07. For more details, see our article on The History of the Op Amp in the August 2021 issue (siliconchip.au/Article/14987). required a staff of nine engineers and mathematicians, plus six technicians. It had 100 dials and 6,000 plug-in connections. Its output devices were two Electronic Associates Variplotters, 18 GE recording voltmeters and a 3D trajectory indicator. It had 4000 valves, 450 precision DC amplifiers, a bank of polystyrene capacitors for 80 simultaneous integrations, hybrid step multipliers and a power consumption of 46kW. Special circuitry was designed to achieve accuracies of 0.001%; the power supply was regulated to that tolerance as well. Convair Analog Computer (1953) It was used for stress analysis of aircraft, and flight simulation, including a cockpit simulator. It had 8500 valves, reportedly occupied several floors and was one of the largest analog computers ever made – see siliconchip.au/ link/acas K2-W (1953) The first commercially available, modular, standardised op amp was George A. Philbrick’s K2-W valve module, released in 1953 (some say 1952) – see Fig.12. It was manufactured until 1971. It is similar to an integrated circuit but based on valves, resistors and capacitors. It was a high-performance device designed for building electronic analog computers. Its design eased the implementation of functions like addition, subtraction, integration, Fig.14: the RCA Typhoon, possibly the largest electronic analog computer ever built. Note the rocket model in the foreground. Source: The Analogue Alternative, James S. Small, 2001 22 Silicon Chip Australia's electronics magazine Fig.12: the first commercially available op amp, the Philbrick K2-W. Source: https://w. wiki/HRd3 Fig.13: the first ‘modern’ IC op amp, the μA741. Source: https://w. wiki/3eHA differentiation, multiplication and division. A modular electronic analog computer for solving differential equations would use a few to dozens of op amps. Philbrick also made several ‘black box’ K3-series electronic analog computer components, which can be viewed at http://philbrickarchive.org/k3_series_ components.htm (see Fig.15). The K2-W was a significant step in the miniaturisation, modularisation and standardisation of electronic analog computers before the development of transistors. Central Air Data Computer (1956) The Bendix Central Air Data Computer was used in US military aircraft such as the F-101, F-111 and the B-58 Fig.15: a K3 Series component from GAP/R. This is an adding unit with four inputs, e1, e2, e3 & e4. Source: http://philbrickarchive.org/k3_series_ components.htm siliconchip.com.au Fig.16: a 1962 model of the Bendix Central Air Data Computer. Source: https://w.wiki/HRcy to compute altitude, airspeed, Mach number and other values from pressure and temperature inputs. It contains two pressure sensors and an analog computer built from gears and servos. It was a masterpiece of engineering, with 46 synchros (a device to convert rotation to electrical outputs), 511 gears, 820 ball bearings and 2781 major parts – see Fig.16 & siliconchip.au/link/aca2 Perceptron (1958) The Mark 1 Perceptron was an artificial neural network algorithm originally simulated by Frank Rosenblatt on an IBM 704 digital computer in 1957 before being built into hardware as the Mark 1 Perceptron electronic analog computer. It could distinguish between simple shapes like squares, circles, diamonds and the letters X, E and F with different orientations. In different experiments, it used between 500 and 1000 ‘neurons’ and was trained with up to 10,000 images. It had three main parts: 1. A set of sensory or S-units comprising a 20×20 array of photocells to receive optical inputs. 2. A set of 512 association or A-units, each of which fired based on inputs from multiple sensory units. 3. A set of 8 response or R-units, which fired based on inputs from multiple association units. The S-units were connected to the A-units via a plugboard (see Fig.17). The A-units were connected to the R-units with adjustable weights encoded in potentiometers, with weight updates adjusted during learning by electric motors. You can read an operator’s manual at https://apps.dtic.mil/sti/tr/pdf/ AD0236965.pdf This was an amazing machine for the time and the precursor to modern AI systems. PACE 231R (1958) This was Electronic Associates’ flagship computer and became the world’s most widely used electronic analog computer, even into the early 1980s – see Fig.18. It was used for simulations for Project Mercury, Project Gemini, HL-10 lifting bodies (famous from the Six Million Dollar Man) and the X-15 rocket plane. For X-15 simulations, NASA used three PACE 231R computers siliconchip.com.au Fig.17: the Mark I Perceptron showing the S-unit to A-unit plugboard. Source: www.researchgate.net/figure/ fig2_345813508 Fig.18: the Pace 231R computer. Fig.19: the AKAT-1 from Poland. A very interesting-looking machine! Source: https://w.wiki/HRcz containing a total of 380 op amps, 101 function generators, 32 servo amplifiers and five multipliers networked together. Simulations could be run between Mach 0.2 and Mach 7.0 at altitudes up to 321km. Landing simulations were not possible. AKAT-1 (1959) From Poland, it was one of the first differential equation analysers based on transistors. It was only ever built as a prototype – see Fig.19. Australia's electronics magazine May 2026  23 Heathkit EC-1 (1960) This was an educational electronic analog computer – see Fig.20. It contained nine op amps. MUDPAC (1961) The Melbourne University Dual Package Analogue Computer was built by Applied Dynamics in the USA, their first computer for export. It was used until 1986. It comprised two consoles, 64 op amps, 80 coefficient potentiometers, 16 multipliers, eight function generators and 20 diode networks. It had a 1632-hole patch panel – see Fig.21. Fig.22: the major components of the instrument unit of the Saturn V. Source: NASA – https://images.nasa.gov/details-0100984 Apollo (1961+) Analog computers played a critical role in the 1960s-1970s Apollo program, for ground simulations and in some on-board systems. Large-scale analog and hybrid analog-digital computers were used extensively on the ground for high-fidelity, real-time simulations of Saturn V rocket dynamics – see Fig.23. For example, the General Purpose Simulator (GPS) at NASA’s Marshall Space Flight Center ran 12-degree-offreedom models of the first stage that incorporated wind gusts, structural flexing and fuel sloshing, all in realtime, which was 3000 times faster than the digital computers of the era could achieve. The GPS comprised 50 integrators, 50 summers, 350 coefficient potentiometers, 20 quarter square multipliers and 15 function generators (which contained an additional 70 op amps). The Flight Control Computer (FCC) of the Saturn V instrument unit (Fig.22) was not purely analog; it was a hybrid analog/digital system (mostly analog for the guidance loops, with some digital logic), translating inertial measurement data into gimbal commands for the F-1 and J-2 engines. In contrast, the famous Apollo Guidance Computer (AGC) carried onboard the Command and Lunar Modules was entirely digital; it was the first real-time embedded digital computer flown in space. It handled navigation guidance and control of the spacecraft itself. At the time (in the 1960s), purely digital computers were too slow and memory-limited to perform the highspeed, continuous, multi-degree-offreedom simulations required for Saturn V development or the fast innerloop control of engine gimbals, which is why analog and hybrid solutions Australia's electronics magazine siliconchip.com.au Fig.20: a Heathkit EC-1 educational electronic analog computer. Source: https://w.wiki/HRc$ Fig.21: the MUDPAC computer used at the University of Melbourne in 1961. Photographer: David Demant, Museums Victoria, https://collections. museumsvictoria.com.au/items/399902 24 Silicon Chip remained indispensable on the ground and in some flight hardware. EAI PACE (1963) The EAI PACE/TR-20 transistor tabletop analog computer was designed for educational use and basic research, even as digital computing was growing in prominence. SR-71 (1964) The SR-71 Mach 3+ aircraft, first flown in 1964, used a hydraulic analog computer of cams, levers, pistons and valves to manage the complex engine inlet airflows and fuel mixtures. Digital computers of the time were not fast enough, small enough, robust enough or heat resistant enough to handle the task. Fig.23: a detailed view of NASA’s General Purpose Simulator, circa 1966. Source: www. joostrekveld. net/?p=1409 Moog synthesiser (1964) While it was a musical instrument, many sources call it an analog computer. It shares roots with electronic analog computers, using the same building blocks like voltage-controlled oscillators, filters, amplifiers and envelope generators derived from op amp circuits. It is arguably a specialised musical analog computer. Nebraska-Kansas dispute (~1966) Early in this dispute concerning the use of groundwater, which has run for decades, an analog computer was built to simulate groundwater flows. Water was pumped out of test wells to determine the land’s water storage capacity and resistance to flow. This was simulated with an analog computer made of a network of 30,400 resistors and an unspecified number of capacitors that took a month to build – see Fig.24. Land with coarse soil, a high storage capacity and low resistance to flow was represented by a high-value capacitor and low-value resistors, while land with fine soil, a low storage capacity and high resistance to flow was represented by low value-­ capacitors and high-value resistors. The output of the water table profile was read on an oscilloscope; future water levels could also be predicted. Fig.24: simulating groundwater flows with a resistor/capacitor network (top). The test well network is shown at bottom, with a high flow well on the left and low flow on the right. Source: Time Life Science Library “Water”, 1966 Fig.25: the Australianmade EAI 180 computer. Source: https:// artsandculture. google.com/ asset/eai-180analog-computerelectronicsassociatesincorporated-eai/ IgG4Y3h75wg07g EAI 180 (1972) An EAI 180 (Fig.25) was used at the University of Sydney, Department of Mechanical Engineering in the 1970s. It was designed by Electronic Associates Pty Ltd of Sydney and built by Hawker Siddeley. It was used in siliconchip.com.au Australia's electronics magazine May 2026  25 the 1970s for teaching engineering students. Prior to this, calculations were made on mainframe computers (if available) or slide rules. It was ultimately replaced for teaching purposes by inexpensive programmable calculators. The Powerhouse Museum notes that this was an Australian version of the EAI 180 from the US parent company; it sold very well in Europe, but was not allowed to be sold in the USA despite being considered a better machine than the one made in the USA. Its reference manual is available at siliconchip.au/link/aca3 Analog Thing (2025) The Analog Thing by anabrid (https://the-analog-thing.org) is an open-source analog computer – see Fig.26. It has five integrators, four summers, two comparators, eight coefficient potentiometers, two multipliers, a panel meter and a hybrid port for analog-digital hybrid programs. Multiple Things can be daisy-chained. It is available for about A$875 + shipping (we suspect our readers could build an equivalent for much less than that). Mechanical vs electronic computers Having looked at some representative mechanical and electronic analog computers, let’s compare them. Cost: mechanical computers are complicated and require expensive precision machining and extensive assembly. Electronic circuits also require high levels of precision, although that is achieved inexpensively by modern manufacturing methods. That makes them easier and cheaper to build, alter and program, unlike a complex mechanical device. Speed: mechanical computers rely on gears, shafts, cams, ball and disc Fig.27: an op-amp-based integrator circuit. 26 Silicon Chip Fig.26: the Analog Thing, an analog computer available for purchase today. mechanical integrators etc. They are limited in speed to a few cycles per second due to mechanical friction, inertia, balance etc. Electronic components such as valves or transistors can easily operate at thousands or millions of cycles per second. Ease of programming: reprogramming a mechanical computer can require complex gear, linkage and other changes, which could take a very long time. On an electronic analog computer, it is just a matter of changing some patch cables, rotating potentiometers, perhaps adding an electronic module with certain functions, etc. Digital and hybrid computers are even easier and quicker to reprogram. • Operational amplifiers (op amps) can be configured to perform addition, subtraction, integration, differentiation and signal amplification. • Diodes and transistors are used for signal conditioning, switching and more complex functions. • Potentiometers or variable resistors can be used for scaling values. • ICs are used for specialised functions in more modern machines. These components can be used to form basic circuit elements or modules of an electronic analog computer, with some examples as follows. Circuit elements & functions The following electronic components are used in an electronic analog computer. • Resistors and capacitors are used for scaling voltages (resistors), creating time delays (RC delay circuit) and forming filters (RC filter). An electronic analog computer comprises some or all of the following. • Amplifiers to boost weak signals. • Filters for processing signals in real-time, to attenuate high or low frequencies. • Function generators and comparators to create waveforms or compare signal levels. They can be built from transistors, diodes and capacitors or specialised ICs or modules. • Integrators and differentiators, as mentioned earlier, are usually built from op amps. • Circuit blocks to perform mathematical operations like addition, subtraction, multiplication, squaring, square rooting, division, exponentiation and logarithms. A differential equation is one that relates a function to one or more of its derivatives (rates of change); solving it involves finding the original function through the process of integration. An integrator circuit can be constructed using an op amp, resistor and capacitor whereby an output voltage Fig.28. an op-amp-based differentiator circuit. Fig.29: an op-amp-based summing circuit. Basic electronic components Australia's electronics magazine siliconchip.com.au is produced from the capacitor which is the integral of a voltage over time, a fundamental of simulating dynamic systems (Fig.27). Similarly, an op amp can be configured for differentiation, in which a voltage output is produced that is proportional to the input voltage’s rate-ofchange with respect to time (Fig.28). Another op amp based circuit is a summing amplifier (for addition) – see Fig.29. An op amp has multiple voltage inputs producing a weighted average of the input voltages. Other mathematical functions can be performed. The logarithm of an input signal can be determined by exploiting the inherent exponential relationship between the base-emitter voltage (Vbe) and collector current (Ic) of a bipolar junction transistor in the feedback loop of an op amp, as shown in Fig.30. The PDF at siliconchip.au/ link/aca4 has more specific details on this method. An analog electronic multiplier takes two analog input signals (usually voltages) and produces an output signal, typically a voltage or current that is proportional to the product of the inputs or, with feedback, their ratio. Beyond simple multiplication and division, analog multipliers can also perform squaring, square rooting, RMS-to-DC conversion and amplitude modulation by exploiting their inherent non-linear characteristics. One implementation of a modern analog multiplier is built around the Gilbert cell, invented in 1967, which is a clever arrangement of transistors whose currents multiply naturally because of the exponential relationship between a transistor’s base-­emitter voltage and its collector current. A modified version of a Gilbert cell is shown in Fig.31; this is Analog Devices’ implementation, as used in the classic but now discontinued Differential equations in computing A differential equation simply tells us how fast something is changing at any instant, for example, the rate at which a falling object accelerates due to the force of gravity acting on it, or the oscillatory acceleration of a mass on a spring due to spring tension. Integration is the reverse operation: it turns a rate of change into the total accumulated quantity, such as the speed of the object as it falls; velocity is the integral of acceleration, and position is the integral of velocity. In an electronic analog computer, differentiation and integration are calculated physically and continuously by the single most important building block, the integrator circuit. It uses just one operational amplifier, one resistor, and one capacitor (see Fig.27). The resistor converts the input voltage (representing the rate of change) into a current that steadily charges or discharges the capacitor; the voltage across the capacitor therefore becomes the running total, which is the mathematical integral of the input, all with virtually zero delay. As an analogy, think of the capacitor as a bucket collecting water (current) at a rate set by the input voltage (pressure); the water level at any moment is the integral, mirrored by the output voltage. Because this happens continuously and in real time, the falling object differential equation d2y/dt2 = -9.8m/s2 can be solved by feeding a constant -9.8V into the first integrator. Its output becomes a steadily rising voltage ramp (velocity), which can then be fed to a second integrator, producing a downward-opening parabolic voltage vs time curve (position). An oscilloscope or chart recorder connected to the output can visualise voltage (y-axis) over time (x-axis) to observe the parabolic trajectory. This is shown in a YouTube video at https://youtu.be/3tOA8Fo6b7A Another example is simple harmonic motion, x’’ + ω2x = 0. Two integrators integrate acceleration (x’’) to velocity (x’) and again to displacement (x) with one or two inverters to correct the signs. That is why analog computers were once called differential analysers: they almost instantly turned differential equations into voltage curves, providing an answer to many engineering problems. On a digital computer in the 1960s, this would have required pages of digital code and seconds or minutes of computation even on the fastest digital machines of the day. The same humble op amp based integrator principle that powered Apollo simulations and 1960s control systems is now reappearing with a different implementation in ultra-low-power-consumption AI chips, proving that for many continuous, real-world problems, analog integration remains unmatched in speed and energy efficiency. Fig.30: in this logarithm converter, Vy is a constant, while Is is a scaling parameter of the transistor. Fig.31: a modified Gilbert cell core, as used in Analog Devices’ AD534. The inputs are Vx and Vy, while the output is E0. Source: www.analog.com/ media/en/training-seminars/tutorials/MT-079.pdf siliconchip.com.au Australia's electronics magazine May 2026  27 Fig.32: a gyrator or synthetic inductor (far left) and its equivalent circuit. Fig.33: some mechanical and electrical analogies. AD534 multiplier chip. It was replaced by the AD633 and AD734, both still available. These chips were widely used in 1970s-1980s analog computing for multiplication, division, powering and root functions. Explaining how the Gilbert cell circuitry works is beyond the scope of this article; interested readers can visit siliconchip.au/link/aca5 and https://w. wiki/HHbV For multiplication, the circuit takes two input voltages Vx and Vy, converts them to currents, multiplies those currents in the transistor core, then converts the result back to an output voltage giving Vout = k × Vx × Vy (where k is a constant, usually about 1/10). By feeding the multiplier’s own output back into one of its inputs (often through an op amp), you get division (Vout = Vx ÷ Vy). Squaring simply involves connecting both inputs together. Square-rooting uses the multiplier in a feedback loop that forces Vout2 = Vin. The same building block, with a few extra resistors or capacitors, can also perform amplitude modulation, frequency doubling, RMS-to-DC conversion and even logarithmic/exponential functions. Another simple circuit that can form part of an electronic analog computer is the Wheatstone bridge. An unknown resistance is found by balancing known resistance values against the unknown. In essence, multiplication and division are performed using calibrated resistors to balance the bridge and find the unknown value. A modified Wheatstone bridge can also be used to compute the tangent of an angle or the hypotenuse Fig.34: the OME P2 is an electronic analog computer made by the Société d’électronique et d’automatisme (SEA) in 1952. It was used for simulations during the development of the Concorde. Source: https://w.wiki/HTe8 (CC-BY-SA 4.0) 28 Silicon Chip Australia's electronics magazine siliconchip.com.au of a right-angle triangle. A circuit to divide and multiply using a Wheatstone bridge was published in the June 1960 edition of Radio-Electronics (see siliconchip.au/link/aca6). As inductors are large for use at low frequencies and have other deficiencies, a gyrator circuit can act as a ‘synthetic inductor’, comprising an op amp, resistor and capacitor – see Fig.32. Electrical and mechanical equivalents One of the main uses of traditional analog computing was to simulate mechanical systems. There were two ways to do this with electronic analog computers: 1. The impedance analogy (force-­ voltage or Maxwell analogy), in which mechanical force corresponds to voltage and velocity to current. 2. The mobility analogy (force-­ current analogy or Firestone), in which force aligns with current and velocity with voltage. Other parameters equating physical and electrical quantities are shown in Table 2. The very name “analog computer” comes from the ability to generate analogies. Some examples are shown in Fig.33. To decide which analogy to apply, the following are considered: If a direct mapping of impedance values is desired, so mechanical impedances match electrical impedances numerically, the impedance analogy (also called the Maxwell analogy) is used. Mechanical impedance measures a system’s resistance to motion, while electrical impedance measures opposition to alternating current. This analogy allows direct quantitative correspondence, but has the disadvantage that the topology is inverted, that is, mechanical series connections become electrical parallel connections and vice versa – see Fig.35. Fig.35: a simple series LCR resonator, mechanical and electrical equivalents. This is the Maxwell analogy, in which mechanical parallel connections become series electrical connections. F = force, S = spring stiffness, M = mass and R = damper resistance. Fig.36: a simple series LCR resonator with mechanical and electrical equivalents. This is the Firestone analogy, in which mechanical parallel connections remain parallel electrical connections. If, instead, it is desired to preserve the physical topology of the system so that the electrical circuit mirrors the mechanical connections, the mobility analogy (also called the Firestone analogy) is chosen. Here, parallel mechanical elements are represented as parallel electrical elements, and series elements remain in series, making this arrangement more intuitive for complex systems. However, the impedances are inverted – see Fig.36. Figs.35 & 36 are electrically series or parallel LCR resonator circuits. Depending on the analogy used, both can be analogues of the same mechanical system, which could be an automotive suspension or engine mount system, a tuned mass damper in a tall building, the suspension of a washing machine drum or aircraft landing gear. The equivalent mechanical device comprises a damper (shock absorber; R or 1/R), a mass representing inertia (L or C) and a spring represented by its stiffness (C or L), all connected in parallel in both cases. As mentioned earlier, rather than using physical inductors for L, impedance inverters (gyrators) are usually used instead. Alternatively, real inductors could be used, but the circuit could be operated at a higher frequency than in reality (eg, 10× or 100×). Next month That’s all we have space for in this issue. As we have already discussed the history of analog computers, the second and final instalment next month will concentrate on their presSC ent and future. Table 2: mechanical and electrical equivalent quantities in analog computing. Quantity Impedance (force-voltage) analogy (Maxwell) Mobility (force-current) analogy (Firestone) Force (F) Voltage (V) Current (I) Velocity (v) Current (I) Voltage (V) Mass (m) Inductance (L) Capacitance (C) Damping (b) Resistance (R) Conductance (G) Spring constant (k) Reciprocal of capacitance (1/C) Reciprocal of inductance (1/L) Displacement (x) Magnetic flux linkage (λ) or charge in some contexts Charge (q) Impedance Preserved (Ze ∝ Zm) siliconchip.com.au Inverted (Ze ∝ 1/Zm) Australia's electronics magazine May 2026  29 Power Amplifier Clipping Indicator Ensure your loudspeakers are protected from being overdriven and possibly damaged or destroyed by building this Power Amplifier Clipping Indicator. Not only does it show when an amplifier clips (however briefly), it can also reduce the signal level applied to the amplifier to limit subsequent clipping, protecting the speakers. By John Clarke A mplifier clipping occurs when the output flat-tops because it cannot increase the output voltage any further due to power supply limitations. This means that the amplifier has reached its limit to deliver power to the loudspeakers. It also means the sound becomes vastly distorted, leading to the sound quality suffering. If clipping is allowed to continue, loudspeakers can be damaged or destroyed. With suitable volume levels, the amplifier reproduces the audio signal faithfully. But if the amplifier is turned up too much and clipping starts to occur, you get a compressed signal 30 Silicon Chip that causes the overall power delivered to the loudspeakers to be greatly increased, causing them to overheat and burn out. Woofers and, to some extent, midrange drivers are less prone to damage than tweeters. This is because they utilise more robust and larger diameter wire in their voice coils than their tweeter counterparts. The tweeter is more delicate, using a thinner, smaller and lighter voice coil so it can move quickly to reproduce higher frequencies. When loudspeakers are overdriven, the voice coil windings can burn out Australia's electronics magazine or the voice coils can soften and permanently distort. Continued excessive overdrive can result in the loudspeaker catching fire and/or fusing. If you want to explore more about loudspeaker damage due to amplifier overloading, see www.sound-au.com/ tweeters.htm and www.sound-au. com/clipping.htm We have previously published three Power Amplifier Clipping Indicator projects, one as a full project and two Circuit Notebook entries. These all detect clipping based on whether signal level peaks approach a fixed voltage difference from the amplifier’s siliconchip.com.au Features & Specifications Detects genuine signal clipping and gross distortion Doesn’t require opening up the amplifier Optional automatic signal reduction at clipping Separate left and right channel clipping indicator LEDs Momentary clipping is shown on LEDs with a minimum 50ms duration Suitable for inverting, non-inverting and bridge-tied amplifiers Uses commonly available components Easy to solder Power supply requirement: 15-24V DC at 200mA supply rails. Typically, this was set at somewhere around 4.7-6.2V less than the supply rails. This level is not necessarily the point of clipping. It depends on the type of driver devices used in the amplifier (whether Mosfets or transistors), the driver device’s temperature, and the loudspeaker impedance. Additionally, to install such a power amplifier clipping indicator requires access to the inside of the amplifier to tap into the power supply rails. This new Clipping Indicator is designed to detect when the amplifier is actually clipping. Only externally available amplifier connections need to be accessed: the input sockets and the speaker outputs. How it works The Clipping Detector works by comparing the signal applied to the amplifier with the output from the amplifier. If the amplifier is not clipping, the two signals should be identical in shape, only differing in voltage magnitude. We compare the signals after reducing the amplifier output level so it matches that of the input. That way, any differences between the two waveform shapes can be detected. A summing amplifier compares the two signals. Typically, the input and output signals of an amplifier will be in phase. So when the input goes positive, the output also goes positive. If we invert the amplifier output signal and then sum the two signals, they should cancel out. If there are any differences, such as phase changes or clipping, the summing amplifier (or ‘adder’) will produce an output that becomes a difference or error signal. We simulated this in LTspice, as shown in Fig.1. The blue trace is the amplifier input, the red trace is the attenuated and inverted amplifier output, while the green trace is the adder output. We have clipped the positive output of the amplifier output a little at the peak of the positive excursion to show how the adder responds to a signal difference. There is a rise in the adder signal level when the two waveforms differ. When the two signals are the same except for being inverted (as shown for the negative excursion), the adder output remains close to 0V. We use the adder output to gauge the amount of difference between the two signals. A window comparator detects when the adder produces a large enough difference signal to trigger the clipping indication. To verify this, Scope 1 shows the amplifier output waveform (yellow trace) at the point of clipping at 104V peak-to-peak. The lower cyan trace shows the output from the summing amplifier, IC2c. The summing amplifier begins to produce a difference signal at the point of clipping on the output waveform. Fig.1: a SPICE simulation of a summing amplifier fed with the inverted input and non-inverted output signals of an amplifier just starting to clip. The output of this ‘adder’ only varies from zero during clipping. siliconchip.com.au Australia's electronics magazine The clipping is asymmetrical, meaning that the degree of clipping in the positive portion of the waveform is greater than in the negative half. This is due to the differences in the power amplifier output transistors used for the positive and negative output drive. Block diagram The block diagram, Fig.2, shows the main sections of the Clipping Indicator. We will describe the sections briefly since there is more detail in the circuit description. The diagram shows the left channel only, and we’ll explain just that channel; the right channel designators are shown in brackets. The signal input at CON1 is from a signal source such as a CD player or preamplifier output. This signal is buffered by IC1a and goes through a high-pass filter to remove signals well below the audible range (sub-20Hz). Following this is the variable attenuator. This acts to reduce the signal level should extended clipping occur. It uses a light-dependent resistor (LDR1) and LED2. The LDR forms a voltage divider with a fixed resistor, providing more attenuation when the LED light intensity increases. Normally, without any light from the LED, the LDR has a very high impedance, so there is minimal attenuation. Thus, this section has no effect on the signal except when the amplifier is driving into clipping. Another buffer follows (IC1d) before the signal is applied to the power amplifier input via CON3. The output from buffer IC1d also goes to two phase-adjustment filters, one for the high-frequency end of the audio spectrum and the other for the low-frequency end of the audio spectrum. These are adjusted to match the phase shifts that occur in the power Scope 1: the amplifier output waveform (yellow) and output from the summing amplifier IC2c (cyan). May 2026  31 amplifier at the lower and upper frequency extremes. These are inherent to most audio amplifiers due to capacitors in the power amplifier causing low-­ frequency roll-off where the input and feedback signals are AC-coupled, and high-frequency roll-off due to the compensation capacitor used to ensure the power amplifier’s stability and possibly other RF/noise filters. We need our clipping detection signal path to have the same phase shift characteristic as the amplifier so we can compare the two signals. Otherwise, they will be different even if there is no clipping, possibly causing false triggering. The output from the phase adjustment filters is applied to the summing amplifier input. The power amplifier output connects to either the CON5 non-­inverting or inverting amplifier input. Most power amplifiers are non-inverting, so the non-inverting input is typically used. The inverting input is mainly included so that you can use this device with a bridge-tied load (BTL) amplifier, where there are two amplifiers driving the loudspeaker with one producing an inverted signal compared to the other. Having the two input options allows for both amplifier outputs to be monitored for BTL amplifiers. The signal level from CON5 is controlled using trimpot VR4 or VR5, or both in the case of a BTL amplifier. The signals are buffered following the attenuators, and in the case of the non-inverting amplifier signal, it is inverted by another op amp, ready for comparison in the summing amplifier using IC2c. IC2c is the summing amplifier described previously, and the resulting summed signal is monitored by a window comparator (IC3). Normally, this signal level will sit close to 0V when there is no clipping. When the summing signal reaches a set level (beyond ±1.25V), the window comparator triggers timer IC4. IC4 provides a 50ms minimum output to drive the clipping LED via transistor driver Q2, ensuring that the flash is visible even for very brief clipping events. This driver also provides a fast attack and slow decay voltage that drives LED2 via transistor Q3. This reduces the resistance of LDR1, attenuating the signal that ultimately is applied to the power amplifier input. Circuit details The full circuit is shown in Fig.3. It comprises four quad op amp ICs and three single op amp ICs for a total of Fig.2: the Clipping Indicator is connected between the preamp (CON1/ CON2) and power amplifier (CON3/CON4). A current-controlled attenuator can reduce the signal going to the amplifier when clipping is detected. After phase adjustments, the input signal is fed to the adder, along with the amplifier signal(s). Its output goes to a window comparator that detects clipping, then a pulse-stretching timer to drive the LEDs. 32 Silicon Chip Australia's electronics magazine 19 op amps, plus three 555 timers and two dual comparators, along with two reed relays and associated diodes, a regulator, resistors and capacitors. Three indicator LEDs indicate clipping in each channel and show when the power is on. As with the block diagram, only the left channel is shown, with the right channel being identical; its alternative designators are shown in brackets. Some op amps provide buffering, some active filtering, while another (IC12) provides a low-impedance half supply. Looking at the audio signal circuitry first, through the circuit the signal common is set at half supply (Vcc/2) so it can swing symmetrically between GND and the 15-24V DC supply rail. This means it can run from a standard DC plugpack without needing a supply voltage inverter section. The signal comes in at the CON1 RCA socket and is biased to ground by a 100kW resistor. This discharges any AC-coupling capacitor that could be in the signal source. A 150W series resistor acts as an RF stopper to prevent radio signals entering the first buffer op amp. Following this, the signal is AC-­ coupled via a 10μF capacitor to the non-inverting input of IC1a. This input is biased to the half supply via a 100kW resistor. A 13Hz high-pass filter rolls off very low frequency components of the signal at 40dB/decade; it is 6dB down at 13Hz. The reason we set this roll-off at 13Hz is so the signal is only 3dB down at the lowest audible threshold at 20Hz. Following the filter is the current-­ controlled attenuator. This comprises a 10kW series resistor in conjunction with LDR1 and trimpot VR2 shunting some signal to the Vcc/2 reference point. Normally, the LDR is in complete darkness and its resistance is around 0.5MW (500kW). In this condition, it produces negligible signal attenuation until clipping is detected. IC1d acts as a buffer for the attenuator. At IC1d’s output, the signal is diverted two ways. One is to the output to the amplifier. This is AC-­ coupled to the relay contact and the 100kW resistor in conjunction with the 10μF capacitor sets the output signal to swing about ground (0V). In other words, the 10μF capacitor removes the Vcc/2 DC bias voltage from the signal. siliconchip.com.au Fig.3: the full circuit with only the left channel shown – the right channel components are identical and their designators are shown in brackets. The sections that are common to both channels are the half-supply rail generator, power supply (including REG1), on-delay and off-delay sections. Following the relay contact, the signal is sent to the RCA socket (CON3) via a 150W resistor. This provides a small series impedance for the op amp so it won’t oscillate when there is a capacitive load connected, such as screened audio cable. siliconchip.com.au The second signal path from IC1d is to the high-frequency phase adjustment circuit. This is a low-pass filter comprising a series 4.7kW resistor, 100kW trimpot (VR2) and a 22pF capacitor. It produces an overall high-frequency roll-off that has an Australia's electronics magazine adjustable -3dB point from 4.6kHz to 102kHz. It is used to match the phase shift within the power amplifier at higher frequencies. IC1b buffers the signal from this filter. Following this is the low-­frequency phase adjustment circuit. It comprises May 2026  33 The board is designed to fit into a UB2 Jiffy box although it also can be incorporated into other equipment, such as a power amplifier. a high-pass filter using a 1μF capacitor and 100kW trimpot in series with a 4.7kW resistor. The range of adjustment for the -3dB point is from 1.6Hz to 34Hz. This allows it to match the power amplifier output phase at low frequencies. IC5 buffers the output of this filter and its output is applied to the summing amplifier (IC2c) via a 10kW mixing resistor. Power amplifier monitoring The power amplifier’s output(s) is/ are connected via CON5 (as well as going to the loudspeaker[s]). There are two inputs. One is the non-inverting amplifier input, while the other is the inverting amplifier input. Most amplifiers are non-inverting, so that input is the most likely the one to use. If you have an inverting power amplifier, simply use the inverting input instead. If your amplifier has a bridge-mode output, where neither terminal is connected to ground but both are actively driven in anti-phase, connect both outputs to the two inputs. In this case, a couple of the summing amplifier resistor mixing values will need changing – more on that later. Trimpots VR4 and VR5 are used to set the signal levels for the non-­ inverted amplifier input and inverted amplifier input, respectively. These are set to match the signal level that is applied to the amplifier input. If one of the inputs is not used, the attenuation is set to maximum to minimise noise. The signal for each input is AC-­ coupled to buffers IC2a and IC2d. The 34 Silicon Chip inverted amplifier signal is applied to the adder via a 10kW resistor, while the non-inverted signal is inverted using the IC2b unity-­ gain inverter first. We invert the non-inverting power amplifier output and don’t invert the inverting power amplifier output so that when the power amplifier input and output signals are summed, the output will be zero. That’s because we are adding two waveforms that are 180° out of phase. The adder sums the signals from the IC5 output and the IC2b and IC2d outputs. When these signals sum to zero, the adder output sits at Vcc/2. Should any of the signals applied to the adder cause a difference output, once that reaches a sufficient level, it will be detected in the following window comparator. Window comparator IC3, a dual LM393 comparator, is connected as a window comparator detecting excursions 1.25V above and 1.25V below the Vcc/2 voltage. The 470W resistor and 1MW feedback resistors add hysteresis so the comparator output does not oscillate when signal at the inverting input (pin 2) of IC3a is close to the +1.25V reference. Resistors of the same values for IC3b prevent this comparator from oscillating if the input at pin 5 via the 470W resistor is close to -1.25V. Australia's electronics magazine IC3a and IC3b have open-­collector outputs, so they can be connected together. These outputs are pulled high via a 10kW resistor to the 12V supply. They remain high if the voltage from the adder remains within ±1.25V of Vcc/2. This is because the inverting input of IC3a is lower than Vcc/2 + 1.25V at the non-­ inverting input, and the non-­inverting input of IC3b is higher than Vcc/2 – 1.25V at its inverting input. If the adder output goes above 1.25V, the IC3a output will go low (near 0V); if it goes below -1.25V, IC3b’s output will go low. In either case, this pulls trigger pin 2 of 555 timer IC4 low, and its pin 3 output goes high. The low voltage at pin 2 also pulls the base of transistor Q1 low, preventing the 1μF capacitor at pin 6 of IC4 from charging via the 47kW resistor. When the comparator outputs go high again, Q1 switches off and the 1μF capacitor can charge. When this voltage reaches 2/3 of the 12V supply (about 8V), the threshold input at pin 6 detects this, and the pin 3 output and pin 7 discharge output go low. The 1μF capacitor is discharged via the 100W resistor at pin 7. The output remains low for some 50ms after the pin 2 input is taken siliconchip.com.au high, extending the clipping indication by 50ms. This allows very short time periods from the comparator to be seen by the user by lighting the LED for long enough to make it visible. While the pin 2 input of IC4 is pulled high via the 10kW resistor to 12V, it does not reach 12V because transistor Q1’s base-collector junction breaks down like a zener diode at about -5V. So the maximum voltage at pin 2 is about 5V. This is more than sufficient voltage to allow trigger operation at pin 2, since the trigger voltage needs to go below 1/3 of the 12V supply (about 4V) to be triggered. When pin 3 is high, it drives transistor Q2 via a 2.2kW resistor, which in turn drives the Clipping Indicator LED (LED1) with its current limited by an 820W resistor from the 12V supply. The high level at pin 3 also begins to charge the 10μF capacitor at Q3’s base via the 10kW resistor, diode D1 and the 100kW resistor. The emitter of Q3 follows the base voltage but 0.7V below the base, and this drives LED2 via an 820W resistor. The longer pin 3 of IC4 is high, the higher the voltage at the emitter of Q3. This means LED2 is driven with a varying current depending on the charge at the 10μF capacitor. When pin 3 of IC4 goes low, the 10μF capacitor at Q3’s base discharges via the 100kW resistor over about one second. When lit, LED2 lowers the resistance of LDR1 at pin 12 of IC1d, so the audio signal is reduced via the voltage divider comprising the 10kW resistor, LDR1 and VR1 to the Vcc/2 reference. VR1 is adjusted for the required amount of attenuation to reduce signal clipping but not so that the signal level drops unnecessarily low. Power supply Power is from a DC plugpack ranging from 15V to 24V. There is no power switch; an inline switch can be used at the DC plugpack output if required, instead of controlling power via the same mains outlet as the power amplifier. Diode D5 provides reverse-­ polarity protection. The supply at its cathode is labelled as Vcc and is typically about 0.7V below the DC input supply voltage. The Vcc/2 supply is derived using two 10kW resistors across this rail, feeding pin 3 of IC12 and bypassed with a 100μF capacitor to ground. IC12 is connected as a unity gain amplifier to siliconchip.com.au Parts List – Power Amplifier Clipping Indicator 1 double-sided, plated-through PCB coded 01104261, 185.5 × 101.5mm 2 white right-angle PCB-mount RCA sockets (CON1, CON3) [Altronics P0147A] 2 red right-angle PCB-mount RCA sockets (CON2, CON4) [Altronics P0144A] 2 3-way PCB-mount screw terminals, 5.08mm spacing (CON5, CON6) 2 2-way PCB-mount screw terminals, 5.08mm spacing (CON7, CON8) 1 PCB-mount DC socket (CON9) [Altronics P0621A, Jaycar PS0520] 2 12V DC coil PCB-mount reed relays (RLY1, RLY2) [Altronics S4101/S4101A, Jaycar SY4032] 2 500kW/2-10kW LDRs (LDR1, LDR2) [Altronics Z1621A, Jaycar RD3485] 6 100kW miniature top-adjust trimpots (VR1-VR3, VR6-VR8) 4 5kW miniature top-adjust trimpots (VR4, VR5, VR9, VR10) 4 14-pin DIL IC sockets 8 8-pin DIL IC sockets 1 50mm length of black 6mm heatshrink tubing 1 strip of Blu-tack or similar non-drying putty Optional case mounting parts 1 197 × 112 × 63mm UB2 box [Altronics H0152/H0202, Jaycar HB6012] 4 25mm M3-tapped standoffs 8 M3 × 6mm machine screws 4 cable glands to suit 3-6mm cable Semiconductors 4 TL074 quad JFET-input op amps, DIP-14 (IC1, IC2, IC6, IC7) 3 TL071 single JFET-input op amps, DIP-8 (IC5, IC10, IC12) 2 LM393 dual single-supply comparators, DIP-8 (IC3, IC8) 3 555 timers (not CMOS types), DIP-8 (IC4, IC9, IC11) 1 7812 12V 1A linear regulator, TO-220 (REG1) 1 LM336-2.5 2.5V reference, TO-92 (REF1) 5 BC337 45V 0.8A NPN transistors, TO-92 (Q2, Q3, Q5-Q7) 2 BC327 45V 0.8A PNP transistors, TO-92 (Q1, Q4) 4 1N4148 75V 200mA signal diodes, DO-35 (D1-D4) 1 1N4004 400V 1A diode, DO-41 (D5) 5 5mm high-intensity red LEDs (LED1-LED5) Capacitors (all 16V radial electrolytic unless noted) 1 470μF 25V 5 100μF SC7649 Kit ($95 + postage) 3 47μF 25V Includes the PCB and all onboard 1 22μF parts. The case and power supply 1 10μF 25V are not included. 10 10μF 2 1μF 2 1μF non-polarised electrolytic 4 220nF 63/100V MKT polyester 13 100nF 63/100V MKT polyester 2 22pF 50V NP0/C0G ceramic Resistors (all ¼W ±1% axial) 4 1MW 4 22kW 5 820W 1 470kW 18 10kW 4 470W 17 100kW 5 4.7kW 4 150W 4 56kW 2 2.2kW 2 100W 2 47kW 4 1kW 2 10W 4 20kW (only for use with bridge-tied load amplifiers) Australia's electronics magazine May 2026  35 buffer this half-supply rail so that loading on that rail doesn’t affect the voltage much. In other words, IC12’s output provides a low impedance source for the components fed from this rail. We use REF1, a 2.5V reference, to provide the Vcc/2 + 1.25V and Vcc/2 – 1.25V reference voltages for the window comparator. So if Vcc/2 is 7.5V, the resulting reference voltages will be 8.75V and 6.25V. REF1 is supplied current via a 1kW resistor from Vcc to the plus (+) terminal of REF1 and another 1kW resistor from the negative terminal to ground. The resulting 2.5V (actually 2.490V) reference is across the Vcc/2 supply using two more 1kW resistors to ensure it’s centred on Vcc/2. There are 100nF bypass capacitors for the Vcc/2 + 1.25V and Vcc/2 – 1.25V rails. The Vcc supply is bypassed with a 470μF capacitor and feeds the input of a 12V regulator (REG1) that supplies 12V to the 555 timers and relays. IC11 is a 555 timer that is used to switch on the audio outputs about 10s after power is switched on. This prevents large voltage excursions in the audio signal by waiting to connect the signal until all the voltage levels have stabilised. IC11 is connected as a monostable timer. At power-on, the discharged 22μF capacitor at pin 2 triggers the 555 so that the pin 3 output goes high (12V) and so the bottom connection of each relay coil is at 12V. At the same time, transistor Q7 is switched on due to its base being supplied with current from the Vcc supply. There is 12V at each end of the relay coil contacts, so the relays remain off. This keeps the relay contacts open and prevents any signal at the audio outputs. After about 10s, the 22μF capacitor charges to about 8V and the threshold input of IC11 detects this as being over 2/3 of its supply voltage and takes its pin 3 output low. This energises the relay coils, closing the relay contacts and allowing audio signals to pass. At switch-off, the 4.7kW resistor supplying current to the base of Q7 does not have voltage, so Q7 switches off due to the 100kW pulldown resistor. That removes power from the relay coils. Diode D4 clamps the back-EMF produced by the coils, preventing damage to transistor Q7 from an excessive voltage transient across the collector and emitter. Construction The Power Amplifier Clipping Indicator is built using a double-sided, plated-through PCB coded 01104261. It measures 185.5 × 101.5mm. You can install the assembled PCB within existing equipment, or it can be fitted into a UB2-size plastic utility box that measures 197 × 112 × 63mm. Follow the overlay diagram, Fig.4, first by installing the resistors and five diodes. Check the value of each resistor before installation by checking its colour code and/or measuring with a multimeter (the latter is less prone to errors due to similar colours). Make sure all the diodes are orientated with their cathode strips as per Fig.4. There are four 10kW resistors below IC2 and IC7 that are marked with an asterisk. These all need to be changed to 20kW after setup if you are applying signal to both the inverting and non-inverting amplifier inputs, such as when connecting to a BTL amplifier. So you may wish to install these 10kW resistors above the PCB surface to make them easier to remove later. We recommend using 10kW first since setting up is easier if each input is connected independently and adjusted for level initially. They can then be changed to 20kW. Next, install the sockets for the ICs, taking care to orientate them with the notches all towards the top of the PCB as shown. The two relays can be installed now as well. Next on the list are the screw terminals (CON5-CON8), RCA sockets (CON1-CON4) and DC socket (CON9). Fig.4: fit the components to the PCB as shown here. Watch the orientations of the ICs, diodes, LEDs, transistors & regulator. 36 Silicon Chip Australia's electronics magazine siliconchip.com.au Make sure the screw terminal openings are towards the nearest outside edge of the PCB. For the RCA sockets, we used white for the left channel and black for the right channel. Red sockets can be used for the right channel sockets instead, as this is the standard colour for the right channel. However, at the time we purchased these, the red sockets were out of stock at Altronics and Jaycar only sells black. We sell red and white pairs on our website at siliconchip.au/Shop/7/2615 because they can be hard to obtain at times. Still, the colour is not absolutely critical as you can tell which inputs and outputs correspond. There are two different values for the trimpots, which are all standard vertical adjust single-turn types. VR1-VR3 and VR6-VR8 are 100kW, while VR4, VR5, VR9 and VR10 are 5kW. These can be installed now. Be sure to place the correct value in each position. The 100kW trimpots may be labelled with code 104 (10 × 104) and the 5kW trimpots with code 502 (50 × 102). The transistors, REF1 and the 12V regulator (REG1) can be mounted now, taking care to orientate them correctly and not get them mixed up. Q1 and Q4 are BC327s, while the remaining transistors are BC337s. REF1 is in the RIGHT IN Once the assembly is ready, shrink down the tubing with a hot air gun. Make sure the LED and LDR leads are orientated on the same plane. The LED leads can then be bent over 180° to be installed into the anode (A) and cathode (K) holes on the PCB, with the LDR leads inserted into their corresponding holes (the LDR is not polarised). Now insert the ICs into their sockets, taking care to match up their pin 1 indicators with the socket notched ends. Also be careful not to mix up the 8-pin ICs as there are TL071, LM393 and 555s in the same package that need to be placed in their correct positions. Panel cutouts If you are planning on installing the Power Amplifier Clipping Indicator in a UB2 enclosure, we have provided a drilling guide diagram (Fig.7). The height positions assume that the PCB is on 25mm standoffs. If you prefer to use a different standoff size, you can move the holes up or down to suit. Cable glands can be used to secure the leads for LED2 & LED4. Setting up The Power Amplifier Clipping Indicator needs to be connected to a power amplifier for setup (one that does not have any tone controls or preamplifier). If you use a preamplifier, connect LEFT OUT RIGHT OUT 15-24V DC LEFT IN same type of TO-92 package as the transistors. Install the capacitors next. The electrolytic types (in cans) need to be orientated with the correct polarity, and the 25V-rated capacitors must be placed where indicated. An electrolytic capacitor’s longer lead is positive, so goes into the pad marked +. The MKT and ceramic types can be installed either way around. LED5 can be installed horizontally with its leads bent by 90° so it can shine through a hole in the side of the case. The LED is positioned so the top of the LED dome is 12mm in front of the PCB edge and the centre of the lens is located 5mm above the top face of the PCB. When bending the leads, make sure the longer anode and shorter cathode are inserted into the correct pads on the PCB. The clipping indicator LEDs (LED1 and LED3) are intended to be wired to two-way screw terminals, either mounted onto the side of the enclosure or remotely using figure-8 wire into a hole in the amplifier or loudspeaker. LED2 and LED4 are used in conjunction with LDR1 and LDR2. These are within lightproof housings made from 20mm lengths of black 6mm diameter heatshrink tubing with Blu-tack sealing out external light at each end. This arrangement is shown in Fig.5. Fig.6: you can download this front panel artwork from siliconchip.com.au/Shop/11/3623 siliconchip.com.au Australia's electronics magazine May 2026  37 Fig.5: the LEDs and LDRs are sealed in heatshrink tubes using Blu-tack at each end so external light can’t get in. The photos show this done for LED2 & LED4. its output to the Power Amplifier Clipping Indicator input, and the audio signal output from the Clipping Indicator to the power amplifier’s inputs. Sometimes, the preamplifier and power amplifier are separate units. However, if you have an integrated power amplifier with an input selector, tone controls and preamplifier included with the power amplifier (eg, a receiver), the preamplifier output and power amplifier input will need to be accessed. These outputs and inputs are usually available. They are often joined with a curved loop of 3.5mm diameter plated brass inserted between the RCA sockets of the preamplifier output and power amplifier input. Older units may have a tape monitor (record monitor) loop that provides the same interconnection for the inputs and outputs. Initially, set trimpots VR1, VR2, VR4-VR7, VR9 & VR10 fully anti-clockwise. Set VR3 and VR8 fully clockwise. Connect LED1 and LED3 to CON7 and CON8 (temporarily if necessary). You will need a source of 20Hz, 1kHz and 20kHz tones at around 1V (RMS) AC. These can be obtained from a computer, smartphone app or signal generator. There are also CDs that have audio tones for test purposes. Computer programs such as Audacity can produce audio tones. The quality of the output, especially at 20Hz and 20kHz, will depend on the sound card/DAC within the phone or computer. Connect the signal source to the Clipping Indicator inputs (CON1 & CON2). Connect one channel, such as the left, first. CON3 (CON4) goes to the left (right) channel power amplifier input, while the power amplifier output goes to CON5 (CON6), using the non-inverted input for most amplifiers, or the inverted amp input for amplifiers that invert. For BTL amplifiers, only connect one of the outputs at a time, setting up each output individually first before changing the 10kW resistors to 20kW. With everything powered up and a 1kHz signal applied, adjust the power amplifier so there is a normal listening volume level, ensuring it is not clipping. The clipping LED will be lit because the trimpots haven’t been adjusted yet. Now adjust the relevant trimpot, VR4 (VR9) or VR5 (VR10), carefully until the clipping LED extinguishes. Try to find the middle of the pot range that allows the clipping LED to remain off. Now set the audio signal to 20kHz and adjust VR2 (VR7) so the clipping LED goes out. Again, find the middle of the suitable range if you can. In the unlikely event that you can’t adjust the trimpot so the LED goes out, the 22pF capacitor for the left (right) channel may need changing. Use a smaller capacitor if VR2 (VR7) is wound fully clockwise. Next, set the audio oscillator to 20Hz and adjust VR3 (VR8) so the clipping LED goes out. If you can’t get the clipping LED to go out when VR3 (VR8) is fully clockwise, the 1μF capacitor for the left (right) channel will need to be larger. This is a non-polarised (NP) capacitor. It’s unlikely that you will need to change this value, though. Now repeat all the same adjustments for the other channel. Adjusting the automatic attenuator (using VR1 for the left channel and VR6 for the right channel) is best done with the loudspeakers disconnected. Apply a normal music signal and wind up the volume until it starts clipping, as indicated by the LEDs. Adjust VR1 and VR6 so that the signal attenuates just enough to stop clipping, except for occasional momentary flashes from the LEDs. After that, if you want, you can test with the loudspeakers connected and make adjustments for the best clipping reduction. Take care that you don’t damage your ears while doing this – wear ear protection. If you’re using high-efficiency loudspeakers and a high-power amplifier, you may need SC to skip this step! Fig.7: the drilling diagram for the sides of the UB2 jiffy box (197 × 112 × 63mm). This diagram is printed at 60% of actual size and all dimensions are in millimetres. 38 Silicon Chip Australia's electronics magazine siliconchip.com.au AAEON ● ABP Electronics Acconeer ● ADM Instrument Engineering Advantech ● AIM Solder Australia AIM Training Altium Altronic Distributors AMD ● Ampec Technologies AppVision ASRock ● Asscon ● Avnet ● BDTronic ● Braemac Chemtools CNS Precision Assembly Coiltek Electronics congatec Australia Control Devices Australia Curiosity Technology ● Deutsch ● Digilent Inc/Emerson Dinkle ● DLC Display Dyne Industries Electro Harmonix ● element 14 Embedded Logic Solutions Emona Instruments Entech Electronics Epson Singapore ESI Technology Ltd ● Europlacer Eurotherm ● Evident Australia Fibocom Wireless Inc Finenet Electronic Circuit Ltd Fluke ● FS Bondtec ● GKG ● Globalink Electronics Glyn Limited GPC Electronics GW-Instek ● Hammond Electronics Harogic Technologies Hawker Richardson HIKMICRO ● Hua Wei Industrial Co Ltd Humiseal/Chase Corp ● HW Technologies IMP Electronics Solutions Industry Update Infineon Technologies Interflux ● Inventec ● Japan Unix ● JBC Soldering ● Juki inc Cirrus ● Keysight Technologies KOH Young ● Kolb Cleaning Technology ● Komax Group inc Schlieuniger ● Leach (SZ) Co Ltd Lintek Liquid Instruments C14 D25 A28 A11 C14 D34 D34 B30 D1 C14 D32 B8 C14 A27 C14 C3 B28 D34 D12 A5 B16 B10 A11 D1 A3 D1 A28 A13 D1 C14 A26 B2 A16 B35 A11 D22 A11 C26 D36 A32 D10 C3 A27 A9 A20 C36 D10 C32 B14 C28 D10 D33 C3 A8 A24 A35 B3 D22 C3 A27 D22 A27 C14 A27 A27 A27 D20 D28 C27 ● denotes – Co-Exhibitor Company/Brand Stand numbers are subject to change 40 Silicon Chip Electrone Rosehill Gardens Event Centre June 3-4 Electronex – The Electronics Design and Assembly Expo & SMCBA Conference returns to Sydney, to be hosted at the Rosehill Gardens Event Centre on the 3rd & 4th of June 2026. Electronex is Australia’s largest exhibition for companies using electronics in design, assembly, manufacture and service. E lectronex – The Electronics Design and Assembly Expo returns to Rosehill Gardens in Sydney on the 3rd & 4th of June 2026. First held in 2010, Electronex is Australia’s major high-tech exhibition for electronics design, assembly, manufacture and service. Over 100 local and international companies will be represented, with the latest technology and innovations on display. Electronex features a wide range of electronic components, surface mount assembly, rework and inspection equipment, test and measurement gear, plus other ancillary products and services. Trade visitors can discuss their specific requirements with contract manufacturers that can design and produce what they need. Noel Gray, Managing Director of show organiser AEE, stated “We are delighted with the response, with the Expo headed for a sellout. Many companies will be launching and demonstrating new products and technology at the event. Visitors can discover how AI is revolutionising the industry.” The event attracts designers, engineers, managers and other enthusiasts and decision-makers who are involved in designing or manufacturing electronic products. Electronex is the only specialised event for the electronics industry in Australia. With many Australian manufacturers focusing on niche products and high-tech applications, the event provides an important focal point for Australia's electronics magazine the industry in Australia and is a valuable networking opportunity. Free Seminars A series of free seminars will also be held on the show floor, with visitors able to attend on the day with no pre-booking required. These sessions will provide an overview of some of the hot topics and key issues for the industry. Topics for the seminars include: » Advancing Physical AI » Power Integrity Measurement Fundamentals siliconchip.com.au neX 2026 » Affordable Yet Versatile Multifunction 12-in-1 Test & Measurement Devices » Transforming Test with AI » IoT Beyond Cellular Coverage – 3GPP NTN » Challenges in PCBA Cleaning & Coatings and Design for Manufacturing Masterclass » Securing the Australian Electronics Supply Chain » Precautions for SDR Series Products Manufacturing » Building Robots in the Age of AI siliconchip.com.au Visit the show website for the program and times: www.electronex. com.au SMCBA symposium The SMCBA will also host an industry symposium designed to engage a broad spectrum of participants with an interest in electronics. Attendees will range from engineering professionals to dedicated hobbyists. Subjects covered include automated high-volume production as well as those focused on hand-assembled prototypes. This dedicated industry event will bring together regional leaders, innovators and solution providers alongside the wider electronics community. It will provide a platform to showcase achievements and capability advancements, explore opportunities for collaboration, and address current challenges. Ultimately, the symposium aims to strengthen the industry as a whole, supporting the development of sovereign capability and contributing to national economic diversity. Competitions will also be held on the show floor, where visitors can test their skills against their peers. The SMCBA will be staging the highly popular Hand Soldering Competition, where contestants can enter on the day to battle to become Australia’s champion Hand Soldering expert. Register to attend the exhibition now for free at www.electronex.com. au Australia's electronics magazine LPKF Laser & Electronics ● Macnica Australia Marque Magnetics Ltd Mastercut Technologies MB Tech ● MEAN WELL ● Mektronics Australia Metcase ● Microchip Technology Micron ● Midori ● Mission 4 Monolothic Power Systems Multicomp Pro ● Multispec Trading Nordic Semiconductor ● NPA Pty Ltd NZFH Ltd Okay Technologies ONboard Solutions Ononmondo ● On-track Technology Oritech Oupiin ● Outerspace PCBWay Pendulum ● Phoenix Contact Pillarhouse ● Powertran ● Precision Electronic Technologies Radytronic ● RAK Wireless Rapid-Tech Raspberry Pi ● Rehm Thermal Systems ● Re-Surface Technologies Rigol Technologies ● Rohde & Schwarz (Australia) ROLEC OKW - ANZ S C Manufacturing Solutions Schurter ● Semitech Semiconductor Sensiron ● Shenzhen Cirket Electronics Shenzhen Sanpin Mould Silvertone Electronics SMCBA Stars Microelectronics PCL Suba Engineering Switches Plus Components Taoglas ● TDK Lambda ● TE Connectivity ● Techal Solutions Teledyne FLIR ● Telit Cinterion ● Thermo Fisher ● Uni-T Instruments ● VGL – Allied Connectors Whats New in Electronics Vicom Australia Win-Source Electronics Viscom ● Wurth Electronics Xentronics Yamaha ● Yokogawa ● A26 B32 C9 A15 C3 A11 B4 D14 C21 D1 A11 A28 A28 C14 A6 A28 C4 B22 D34 C3 A28 C23 D22 D1 B25 A10 D10 D18 C3 D1 D26 D1 A28 D10 C14 C3 C28 B2 C8 D14 A2 C14 D6 A28 C13 B1 C26 D21 D3 A27 C4 A28 A28 C14 C22 D10 A28 A11 D10 C10 A33 D13 B33 C3 B20 A14 C28 D10 electronex.com.au May 2026  41 ABP Electronics Limited abp.net.cn stand D25 ABP provides development and manufacturing services for PCBA and finished products. For sample and small batch orders, we can provide fast quotation, fast production and fast delivery. ABP has ISO9001, ISO13485 and IATF16949 certifications and we guarantee our customers stable and qualified products. Our high-quality PCBs provide reliable electronic interconnects and mechanical support. We manufacture singlelayer, double-layer and multilayer PCBs (up to 20+ layers) using FR-4, high-Tg, aluminium-base, Rogers and other substrates. Capabilities include fine-line and spacing down to 3/3mil, blind and buried vias, controlled impedance, HDI structures and heavy copper designs. Surface finishes include ENIG, HASL, OSP, immersion silver and hard gold. All boards comply with RoHS and IPC standards, backed by rigorous quality controls including 100% AOI, flying-probe/ ICT testing and thermal stress verification. ABP’s PCBA service provides complete, turnkey manufacturing from component sourcing to final functional testing. We support SMT, through-hole (THT), mixed-technology and advanced packaging including BGA, µBGA, 0201/01005 chip components, fine-pitch QFN/QFP, and press-fit connectors. With nitrogen reflow, selective soldering, automated optical inspection (AOI), X-ray (AXI) and in-circuit/functional testing, we consistently meet IPC-A-610 Class II and III standards. Additional processes include conformal coating, potting and box-build integration when required. ABP maintains a robust supply chain, ESD-safe and cleanroom environments, full traceability and component authenticity verification. Altronic Distributors Pty Ltd altronics.com.au stand D1 Altronics introduces the S 8741 and S 8742B HD inspection cameras. Engineered for installers, electricians and plumbers, these rugged tools provide a high-definition window into the most inaccessible spaces. The S 8741 (bottom) is a 1m Wi-Fi enabled camera that creates its own hotspot, streaming 720p HD video directly to your smartphone or tablet with a range of up to 15m. For more intensive tasks, the S 8742B (top) offers a 5m reach with a 4.3-inch LCD screen, eliminating the need for external devices. Both models feature IP67-rated waterproof camera heads (8mm and 9mm) and integrated adjustable LED lighting. Say goodbye to disposable canned air. The T 1348 rechargeable USB jet blower is a high-power solution for cleaning sensitive electronics. Driven by 42 Silicon Chip a brushless DC motor reaching up to 130,000RPM, it delivers a concentrated blast of air to remove dust from PCBs, server racks and intricate machinery. It has four adjustable speed settings and a removable magnetic nozzle. A 2500mAh internal battery provides up to two hours of operation. The professional-grade T 1576 hydraulic crimping tool delivers a massive 80kN of force, ensuring cold-welded, gas-tight connections for copper lugs from 4mm2 to 70mm2. It comes with eight interchangeable hexagonal dies, all with a high-strength chrome finish to resist wear and corrosion. Its ergonomic design includes a rubberised anti-slip handle and a quick-release knob. The T 1576 ensures that your high-current connections are safe, secure and compliant. The T 2181 interchangeable multi-tool features a single ergonomic high-carbon steel handle with five specialised, snap-in heads: heavy-duty pliers, a cable cutter, a wire stripper, crimping pliers and stainless steel scissors. Each is crafted from premium materials, such as 60CRV and 40CR13 steel, to ensure durability. Housed in a compact, portable carry case, the T 2181 is the ultimate space-saving solution for site visits and rapid repairs. The X 0437 USB camera magnifier is a versatile tool that bridges the gap between traditional loupes and desktop microscopes, featuring a 2.8-inch integrated circular screen. Offering four magnification levels (5×, 7×, 9× and 12×), it is equipped with dual light sources: seven white LEDs for standard inspection and four UV LEDs for specialised detection tasks like counterfeit identification and fluid leak analysis. With SD card support for capturing stills and video, plus a 3.5-hour battery life, the X 0437 is the perfect companion for the modern technician’s workbench or field kit. The X 0438 handheld magnifier camera is indispensable for PCB troubleshooting, analysis and quality control. It has a vibrant screen with 500× magnification in a compact, handheld form factor. Its internal 900mAh battery allows for 2.5 hours of field use, while the USB-C connectivity enables seamless PC and Mac integration. Adjustable LED illumination eliminates shadows, ensuring that even the smallest solder bridge or hairline fracture is visible. The X 4306A HD digital microscope is designed for precision electronics work, biological study and quality control, with a 7-inch HD LCD screen (1024 × 600px) that provides a clear view of the smallest components. Equipped with a high-performance 12MP camera, the X 4306A offers magnification levels up to 1200×, making it ideal for identifying hairline fractures in solder joints or inspecting intricate PCB traces. The unit features an adjustable metal stand that can tilt up to 45°, allowing for ergonomic viewing and better access for soldering tools under ...continued on page 51 Australia's electronics magazine siliconchip.com.au Mega May SALE! Tech savings across the range. Only until May 31st. SAVE 20% 50 $ altronics.com.au Easy USB recharging! 12V Lithium USB Cordless Driver/Drill Suitable for light to medium duty drilling and driving tasks. Removes screws with ease with its 4.5nm torque drive, adjustable clutch and variable speed trigger - it even has a battery readout on the back! T 2126 NEW! 69.95 $ T 2168A 24% OFF! 22 $ X 2386 4W 500 Lumen Features 1/4” and 4mm drive handles 30 $ X 2387 7W 800 Lumen LED Solar Sensor Lights Add instant security to your place with these weather and rust resistant solar lights! Require no wiring and are IP54 rated for use outdoors. 3 dusk activated light modes. 69 Pc Dual Ratchet Driver Kit Superb quality ratchet driver with a wide selection of bits for most electronic jobs. Includes both a 1/4” adjustable angle (<90°) ratchet handle and a smaller 4mm ratchet handle. Great for the home handyman or enthusiast. SAVE $30 SAVE $30 $ 199 $ C 8825 C 8885 Dual Mic Wireless Karaoke Mixer Offers UHF wireless mics, Bluetooth, HDMI/optical/3.5 mm connections, adjustable DSP (reverb, echo, bass, treble), and supports two wired mics — perfect for parties and home entertainment. SAVE $40 179 $ C 5060A Microlab® Bookshelf Speakers are back! Offering great performance at an amazing price point, the Microlab B77BT offer rich full sound & wireless connectivity. Perfect for gaming, music and movies. Featuring walnut finish cabinets and cloth grilles. 299 Affordable Pro Wireless Sound Always charged and ready to go, this wireless mic system is a great choice for your house of worship or sporting club. Crystal clear interference free operation. 38 UHF channels with easy instant mic pairing. 68W Compact Soldering Station BEST SELLER! Offers convenience and plenty of power with precise dial control and temperature lock. Sleeper stand shuts down the unit when not in use saving on power costs. Includes fine 1.2mm chisel tip, solder reel holder and tip sponge. SAVE $26 T 2040 99 $ Your electronics supplier since 1976. Shop in-store at one of our 11 locations around Australia: WA » PERTH » JOONDALUP » CANNINGTON » MIDLAND » MYAREE » BALCATTA VIC » SPRINGVALE » AIRPORT WEST QLD » VIRGINIA NSW » AUBURN SA » PROSPECT Sale ends May 31st 2026. Build It Yourself Electronics Centre® Home Essentials. Inspect-A-Gadget LED Magnifier SAVE 20% 64 $ With over 5000 units sold, our 95mm illuminated desk magnifier is an absolute bargain at under $70! Every bit as useful as expensive brand name versions which sell for up to $300! An incredible visual aid for work on fine items with full clarity through the quality glass lens. Tackle complex miniature tasks with confidence. X 0102 SAVE 22% NEW! 22 19.95 $ $ A 1014 Universal Aircon Remote Lost your aircon remote? This replacement works with 100’s of brands. Very easy to program. A 1009A Simple TV Remote $15 OFF THIS MONTH! Mini Ultrasonic Cleaner A simple universal IR learning remote for TV’s, fans and more! Requires 2xAAA batteries. 60 65 $ Best seller - make mums jewellery sparkle! Also cleans small parts, glasses and more with just water and liquid detergent. 35W power. X 4204 3+12 Dioptre $ X 4205 5 Dioptre Perfect for the family hot desk! D 2367 D 2363B WAS $99 69 Plugs into MacBook Pro/Air USB C connections and provides a full suite of peripheral connections including card reader. 100W passthrough charging. This handy indoor/ outdoor weather monitor provides temperature, humidity, clock & calendar in one handy jumbo readout. Includes wireless sensor. SAVE $40 99 $ MacBook Docking Hub Keep an eye on the weather $ 13 In 1 USB C Laptop Docking Station A handy laptop docking station hub for USB C type equipped laptops. Fitted with all the ports you could need! Max 4K <at> 30Hz. X 7014 NEW! 34.95 $ Handy Desktop Weather Monitor Rechargeable USB Sensor Light X 0212A SAVE 10% SAVE 20% 2 for $ 29 32 $ Rugged USB Torch Durable all purpose metal 5 Watt USB rechargeable torch. Can be used as an emergency power battery bank. 182mm long. Monitor indoor temperature & humidity with high/low display. Easy to read backlit screen. Three colour & dimmable! A handy 40cm sensor light with in-built USB rechargeable battery. Great for wardrobes. 30s on time. Detaches for recharging. X 3229 Wardrobe Sensor Light Kit At less than $20 you can afford to put these 4xAAA battery powered sensor lights in every cupboard! 1m LED strip length. SAVE 22% 20 $ Countdown Timer & Stopwatch SAVE 22% 2 for $ 70 X 2396 SCAN TO FOLLOW US! Stay up to date on latest releases, exclusive specials and news on our socials. X 7011 Great night light for kids! Compact and lightweight 2-in-1 magnetic timer will help you manage your time with ease - whether it’s for schools, the office or at home. SAVE 17% X 4015 19 $ Like our service? Review your store on Google. Every review helps us serve you better. A must have reference for your projects in the year ahead. 2026-27 Catalogue OUT NOW! FREE with any order or download your copy at www.altronics.com.au/catalogue/ NO STRESS 30 DAY RETURNS! GOT A QUESTION? Not satisfied or not suitable? No worries! Return it in original condition within 30 days and get a refund. Ask us! Email us any time at: customerservice<at>altronics.com.au Conditions apply - see website. Power Gadgets! S 2694 SAVE $50 99 $ Now with LiFePo4 support M 8534B 4.5A SAVE $20 99 $ M 8536B 10A M 8521B SAVE $40 SAVE 16% 159 $ 49 $ Handy Battery Maintainer 6V/12V Battery Chargers & Maintainers Utilises a microprocessor to ensure your battery is maintained in tip-top condition whenever you need it. Helps to extend battery service life. Suitable for permanent connection for battery maintenance. Great for caravans & seldom used vehicles. Weather resistant IP65 casing. Suits lead acid, AGM & LiFePO4. Hassle free maintenance charging for vehicle & LiFePO4 lithium batteries. Protects your car battery when parked for extended periods. 6/12V 1.5A output. Compact DC Power Hub & Isolator Measuring just 160x160x80mm, this box is packed with connections, including 50A Anderson style inputs and outputs, 60W USB charger, 2 x car accessory sockets. SAVE 15% 19 $ D 2326A M 8882B SAVE $24 SAVE $50 150 $ Recharge TEN devices at once. Ultimate benchtop charging station! Great for families, class rooms & business. Massive 200W charge output across 10 x USB type C’s. Includes two desk device holders. BONUS: 5 x USB cables to suit! Valued at $53.75 (15cm C-C type P1998C ) 15W USB Fast Charging Pad Delivers fast wireless charging. Its lightweight design makes it perfect for home, the office, or travel. *phone used for illustration purposes only SAVE $30 Lithium-Ion Vehicle Jump Starter & Power Bank 279 $ M 8195C Don’t get stuck with a dud battery! Suits 12V battery vehicles. 24000mAh rated battery provides up to 2400A peak output when cranking. A 90W USB PD output is provided for your laptop (use it like a giant battery bank!). It also has a 600 lumen LED torch in built. Easy DIY install! Great for 4WDs 99 $ SAVE 10% 35 SAVE 15% M 8867 M 8863B 25 140W USB Power Delivery Car Charger 45W USB PD Charger Charge up all your devices from your vehicle! Provides 140W USB C Power Delivery (PD3.0/3.1). Fitted with convenient 2m cable. QuickCharge 3.0 port as well as a USB C port to suit the latest devices. SCAN TO FOLLOW US! Stay up to date on latest releases, exclusive specials and news on our socials. $ $ N 2099A Monitor your battery from your phone! Ensure your battery doesn’t go flat with this handy Bluetooth® battery monitor. Provides live feedback on your vehicle or auxiliary battery, plus long term stats. Like our service? Review your store on Google. Every review helps us serve you better. AV Savers. BT 5.4 Audio Receiver C 9022B SAVE $30 Compact wireless audio receiver to add streaming to any existing amplifier. 10m range with NFC fast pairing. Premium build & sound! 99 $ NEW! 49.95 $ A 1104A SAVE $50 D 2321 289 $ 16 Channel Mixer With USB Player & DSP A 2652 A great small venue audio mixer! Featuring USB playback with easy to use controls. Plenty of connection options, all top mounted. MP3 recording capability and Bluetooth receiver for your smartphone. USB powered. SAVE 18% 45 $ FutureTour X ANC Headphones The latest design from HiFuture Featuring hybrid active noise cancellation (ANC) that dynamically silences ambient noise. Premium build and feel with playback time up to a whopping 35 hours! Stay charged. Stay on time! A stylish bedside alarm clock with 15W wireless charging for your phone & FM radio. Display also shows calendar & temperature. SAVE 19% 65 $ A 3104 Mini 8K 2 Way HDMI Switcher Offering 8K <at> 60Hz resolution this HDMI selector is ready for the latest high res AV sources. Auto/manual signal switching. SAVE $25 SAVE $70 129 $ 209 $ 8K 4 Way HDMI Switcher A 3105 Professional 8K 2 Way HDMI Splitter 8K <at> 60Hz splitter with EDID management for seamless HDMI source splitting. Ideal for venues, business signage and multi screen display requirements. 8K <at> 60Hz switching with IR remote control for easy source selection from your couch. Auto/manual signal switching. SAVE $60 SAVE $100 179 $ 299 $ C 5205 A 4201 Powerful & compact! H 8126D SAVE $30 2x50W RMS Bluetooth Stereo Amplifier Stream audio directly from your device to your speakers in the study or entertaining area. 3.5mm and RCA inputs. Class D design. Internal headphone amplifier. Includes power supply, banana speaker plugs & 3.5mm to RCA cable. Slides side to side to make stud wall mounting easy. 150 $ Boomin’ 200W RMS 10” Sub! Cantilever Arm TV Bracket Silky smooth cantilever adjustment, stays just where you want it to. It even has 15° of tilt adjustment. Engineered for flat screens up to 90” using 800 x 400mm VESA. Max weight, 60kg. This stunning active home cinema subwoofer adds plenty of bass to any home sound system. Features auto power on, level control, crossover adjustment, and phase reversal switch. Size: 442 x 246 x 410mm. NO STRESS 30 DAY RETURNS! GOT A QUESTION? Not satisfied or not suitable? No worries! Return it in original condition within 30 days and get a refund. Ask us! Email us any time at: customerservice<at>altronics.com.au Conditions apply - see website. A 3106 T 2460A Tools Galore! 3 preset channels for quick temp selection. X 4306A SAVE $120 SAVE 21% 319 55 $ Micron® Touchscreen Soldering Station USB Lithium Rotary Tool Set A sturdy 100W benchtop soldering station featuring an all aluminium case and 2.8” touchscreen for quick temperature and preset selection. 100-500°C temp range with slimline handle featuring burn resistant cable. ESD safe design. Fast heat up and recovery. Works with SMD tweezer handle T 2461A ($219). Drills, cuts, sharpens, cleans, polishes and engraves most surfaces, this rotary tool is ideal for enthusiasts, hobby makers, or just odd jobs around the house. 5 speeds from 5000 to 25000RPM. USB C recharge with 60 mins operation. 42 accessories included. T 2125 NEW! 229 $ $ Digital Microscope Camera Inspect the finest details with this 12MP digital microscope featuring up to 1200x magnification, a vibrant 7” HD display, LED lighting, photo/video recording, and USB PC connectivity. SAVE $20 79 $ Q 1058 SAVE $30 SAVE $30 99 Great for cleaning jewellery & more!! 109 $ X 0103A $ Ultimate all in one electronic screwdriver set. Folding Auto Ranging Multimeter Clean & rejuvenate tiny parts Uses water and detergent, coupled with ultrasonic waves to clean jewellery, small parts etc, without damage - no solvents required. 180x87x58mm tank. Provides in depth functionality for technicians. Folding design stays put on any surface while testing, making it great for auto electrical work. 22 $ T 2748A SAVE 15% Handy Plier & Cutter Set T 2758A A must have for any electronics enthusiast. Includes: • Side cutters. • Flat long needle nose pliers. • Flat bent needle nose pliers. • Long nose pliers/cutters. • Bull nose pliers/cutters This Jakemy® electronic screwdriver set is great for device repairs and other maintenance tasks. Driver offers three-speed torque options with automatic power save mode. Unique folding case houses all 180 bits and accessories. T 1526 1-3.2mm2 T 1527 0.5-2mm2 Best seller! SAVE 25% 19 $ 5” Side Cutters Tough carbon steel blades, stay sharp longer. Ideal for cutting solid core wires. 130mm. SCAN TO FOLLOW US! Stay up to date on latest releases, exclusive specials and news on our socials. T 2130 T 2754B SAVE 15% 15 $ Or buy 2 for $28 Stainless Steel Nippers High quality stainless steel spring loaded nippers for electronics use. SAVE 24% 23 $ Strip Wires Faster! The classic easy squeeze spring loaded quick action wire strippers. Like our service? Review your store on Google. Every review helps us serve you better. Stock up & save. Handy Breadboard Our most popular size circuit development breadboard. 830 holes. SAVE 22% P 1021 Pin to Socket P 1022 Pin to Pin P 1023 Socket to Socket 4 $ ea Ribbon Jumper Leads P 8657 4 Gland Easy peel apart cables. SAVE 19% SAVE 15% 2 for $ 13 $ 24 P 1014A 140pc P 1009A SAVE 22% 25 $ 7 P 1018A 350pc SAVE 20% Breadboard Power Supply 3.3/5V output. 6-12V DC input. 15.95 K 9642 LED Assortment Pack 3mm and 5mm LEDs in green, red, blue, yellow and white. 300pcs. H 1801 11.95 $ 19.95 $ Model Type ONLY P8655 2 Way P8656 3 Way P8657 4 Way P8659 6 Way $18.50 $19.95 $24.95 $26.95 SAVE 20% 15.95 $ K 9645 90° K 9646 Straight K 9643 90° K 9641 Straight 1.25mm Connection Kit 2.54mm Connection Kit Single row header connectors. Includes male & female pin headers, plus 2.54mm housings. Boxed 1.25mm PCB connectors and plugs in 2, 3, 4 and 5 way. Plus crimp pins. 150pcs total. Boxed 2.54mm PCB connectors and plugs in 2, 3, 4 and 5 way. Plus crimp pins. 150pcs total. High Temperature Polyimide Tape Great for 3D printing and other electronics applications. Leaves no residue! Model Width NOW T 2971A 8mm T 2972A 12mm T 2973A 16mm T-Tap Crimp Connectors T 2974A 19mm Designed to tap into a wire mid-span without the need to cut, strip, or solder. A perfect time-saving solution for vehicle wiring. 120pcs from 22-10AWG T 2975A 24mm T 2976A 36mm T 2978A 70mm $9.75 $14.50 $13.50 $13.75 $14 $25 $40 SAVE 10% 22 $ 171pcs, 75mm/45mm lengths in 3.2-12.7mm. 2:1 shrink ratio. T 1090 0.5mm T 1100 0.8mm T 1110 1mm SAVE 15% 26 $ Quality Leaded Solder 60/40 leaded resin core. 200 gram rolls. T 1075 0.5mm T 1078 0.8mm T 1080 1mm 18 $ 57 $ Tin 99.3%, Copper 0.7%. 250gram rolls. Easy way to make quick wire joins. Includes 10 white, 20 red, 15 blue and 5 yellow splices. SAVE 20% SAVE 16% Premium Lead Free Solder Solder Splice 50 Pack Multi Colour Heat Shrink Pack W 0887 W 0884A NO STRESS 30 DAY RETURNS! GOT A QUESTION? Not satisfied or not suitable? No worries! Return it in original condition within 30 days and get a refund. Ask us! Email us any time at: customerservice<at>altronics.com.au Conditions apply - see website. 15.95 $ 310pc Jumper Header Kit 15% OFF NEW! P 8659 6 Gland SAVE 20% SAVE 20% $ 210 pieces of 45mm and 75mm long heat shrink. Size 2.5- 20mm. 2:1 shrink ratio. Great build quality with IP68 rated sealing and screw terminal block. Z 6355 Pre cut and trimmed solid core wire for breadboarding. Red/Black Heat Shrink Pack Waterproof Junction Boxes $ ea Prototyping Wire Z 0003 Wiring problem solver! SAVE 15% SAVE 22% 28 $ W 0816 Maker Bits. SAVE 10% Z 6240A UNO R4 27 $ SAVE $20 Top seller! 99 $ Z 6315A SAVE 24% 25 $ Includes UNO R3 165 Piece Arduino Parts Pack Includes a huge selection of sensor boards, LEDs, pots, jumper wires, a breadboard, LCD screen and much more! Plus a UNO R3 compatible board to get you designing fast. A handy storage case keeps it neat when you’re finished. SAVE 15% Z 6385A ZW6240A UNO R4 WiFi ESP32 Wi-Fi & Bluetooth Board 42 $ UNO R4 Compatible Boards A development board integrating 802.11b/g/n WiFi, Bluetooth 4.2 and BLE. Fully Arduino compatible and perfect for wireless projects. Get designing on the UNO R4 compatible development boards - same form factor as earlier Arduinos for maximum shield compatibility, but with expanded memory and faster clock speed. Z 6497 Z 6317 SAVE 24% SAVE 19% 15 $ Temperature & Humidity Controller A 2 channel board which activates a connected load at preset temperature (-20 to 60°C) or humidity (0-100%). Runs off 12V DC with 10A relay outputs. Z 6319 SAVE 19% 24 8 $ Digital Temperature Controller The STC-1000 controller is a 12V DC heating/ cooling controller allowing you to activate or deactivate loads up to 10A. Includes 1m sensor. $ Precision Temperature Controller 12V input with single 10A relay for on/off control. Waterproof sensor with -30 to +110°C range and 0.1°C accuracy. In-built 3 digit display. SAVE 22% 14 $ Z 6316 Z 6494 SAVE 28% SAVE 24% 20 $ Z 6489 15 $ Bluetooth Relay Board 60W Digital Power Amp Dual 12V 10A relay and control board with the ability to switch on and off loads using eWeLink app on your phone. A high-performance audio amplifier designed for applications requiring compact size, low resistance, and high power output. TPA3118 chip. Z 6427 Wi-Fi ESP8266 Relay Module A handy Wi-Fi activated 3A relay module for wireless switching applications. 3.3V input. Z 6334 SAVE 19% SAVE 24% 8 $ ea 6 $ Turn a USB charger into a power supply. Allows you to connect to a USB PD power supply and output 5, 9, 12, 15 or 20 Volts. DC-DC Buck Module Generate a lower voltage output from a higher supply. 3-40V DC in, 1.5-35V DC out. 3A max. Sale Ends May 31st 2025 Shop in-store at one of our 11 locations around Australia: WA » PERTH » JOONDALUP » CANNINGTON » MIDLAND » MYAREE » BALCATTA VIC » SPRINGVALE » AIRPORT WEST QLD » VIRGINIA NSW » AUBURN SA » PROSPECT Or find a local reseller at: altronics.com.au/storelocations/dealers/ Shop online 24/7 <at> altronics.com.au © Altronics 2026. E&OE. Prices stated herein are only valid until date shown or until stocks run out. Prices include GST and exclude freight and insurance. See latest catalogue for freight rates. B 0005 the lens. It has onboard microSD recording for photos and video, plus USB connectivity for PC-based analysis. congatec Australia Pty Ltd congatec.com stand B16 congatec has unveiled the industry’s most comprehensive lineup of Computer-on-Modules (COMs) powered by Intel Core Ultra Series 3 processors, delivering exceptional on-module AI performance and eliminating the need for discrete accelerator cards in many embedded applications. There are five new COMs across four form factors, from COM-HPC Mini and COM-HPC Client to COM Express Mini and COM Express Compact variants. With up to 16 CPU cores, an integrated NPU5 delivering up to 50TOPS for low-power AI inferencing, and up to 12 Xe3 GPU cores supporting ~120TOPS, developers can run local NLP, LLM execution, image classification, sensor fusion and advanced SLAM without added hardware. With high-speed I/O such as PCIe Gen5 and USB4, these COMs enable high-bandwidth connectivity and performance density in size, weight and power (SWaP)-optimised designs. The broad OS support—including Windows, Linux and realtime systems—plus application-ready aReady.COM options accelerate development, reduce system complexity and cut time-to-market for embedded AI solutions. The conga-HPC/mIQ-X COM-HPC Mini Computer-onModule, powered by Qualcomm Dragonwing IQ-X processors, has up to 12 Oryon CPU cores and a dedicated Qualcomm Hexagon NPU capable of up to 45TOPS AI performance. The credit-card-sized module (95 × 70mm) integrates up to 64GB of soldered LPDDR5X memory and supports an extended temperature range of -40°C to +85°C. Connectivity includes 2× 2.5GB Ethernet, up to 16 PCIe Gen3/4 lanes, USB4, USB 3.2 and multiple camera interfaces. The module has exceptional AI and graphics processing with an integrated Adreno GPU supporting up to 8K resolution and three displays, enabling advanced vision and analytics without external accelerators. With support for UEFI firmware and Windows on Arm, development cycles are simplified, reducing time to market. It is also available as application-ready aReady. COM, with pre-validated OS and software building blocks to jump-start deployments and lower design effort and cost. congatec is expanding its railway certification program for the COM Express module family. In accordance with IEC 60068 environmental standards and IEC 61373 railway shock and vibration requirements, congatec’s COM Express Compact Type 6 modules are proven for longterm operation under extreme mechanical and climatic stress. congatec’s new congaTCRP1 COM Express 3.1 Type 6 compact computer-onmodules integrates the latest AMD Ryzen AI Embedded P100 Series processors to accelerate embedded AI applications with a balanced mix of CPU, siliconchip.com.au GPU and dedicated AI performance. These modules run in environments from -40°C to +85°C, making them suitable for sectors such as transportation, smart infrastructure, medical technology, robotics, retail/POS and industrial automation. Combining AMD Zen5 performance and energy-efficient Zen5c CPU cores, an RDNA 3.5 GPU and an XDNA 2 NPU delivering up to 50TOPS, it achieves up to 59TOPS of combined AI inferencing performance. The TDP is configurable from 15W to 54W with up to 96GB of DDR5-5600 RAM and optional ECC. Connectivity includes PCIe Gen4, 2.5GbE, USB3.2 and SATA/ NVMe. It is available in application-ready aReady.COM variants. Control Devices Australia Pty Ltd controldevices.com.au stand B10 The Micra-M Max digital panel meter sets the b e n ch ma r k fo r h i g h performance industrial monitoring. Engineered for maximum versatility, this digital panel meter bridges the gap between hardware reliability and modern IoT connectivity. It is a multi-input powerhouse, supporting process signals (mA, V), temperature sensors (Pt100, thermocouples J/K/T/N), and load cells. Its tri-colour programmable display allows operators to assign green, amber or red to specific alarm states for instant visual diagnostics. The latest firmware supports an extended display range of up to 99,999 points. • Integrated Bluetooth enables seamless setup via the Ditel Connect Mobile App, while a built-in webserver allows real-time data viewing from any browser • Native MQTT compatibility ensures automatic data transmission to the cloud, facilitating remote monitoring and asset management • A REST API allows developers to integrate live data into third-party software or automation platforms The PK CAN-bus keypad series redefines user interaction by integrating programmable OLED displays directly into the keypad’s keys. This allows a single device to manage complex functions without cluttering the control panel. Each key acts as a functional window, capable of showing icons, scrolling text, or real-time status updates. • Users can toggle through sub-menus where key labels change instantly based on the current operation • Immediate confirmation of commands through colour changes or animated icons • Consolidates multiple bulky switches into one compact, intelligent array Despite its high-tech display integration, the PKD Series does not compromise on APEM’s signature durability. Its robust construction is designed for long-cycle reliability. The keys provide a positive tactile snap. The APEM PKI Series stands out as an advanced solution for complex industrial control. The PKI Series integrates CANbus technology, transforming a standard keypad into an intelligent node within a networked system. Using J1939 or CAN-open protocols, these keypads significantly reduce wiring complexity, Australia's electronics magazine May 2026  51 requiring only a four-wire connection to manage multiple functions. This simplifies installation and enhances system diagnostics and reliability. It is built for the extremes and designed for rugged environments—from agricultural machinery to heavy construction equipment. The PKI Series boasts: • High-intensity RGB LED backlighting ensures visibility in low-light conditions, with programmable status indicators for real-time feedback • Engineered with high-travel silicone keys that provide distinct tactile feedback, even when operated with heavy gloves • Rated at IP67 and IP69K, these units are impervious to high-pressure wash-downs, dust and salt spray Digilent Inc digilent.com stand A3 Our customisable solutions accelerate development for even the most experienced professionals, while maintaining a low barrier to entry for advancing engineers. The new USB 3.0 Analog Discovery Pro 2440 (shown below) and Analog Discovery Pro 2450 portable high-resolution MSOs deliver serious measurements for engineers. They have: • Four analog inputs at either 12-bit, 600MS/s, 100+MHz bandwidth (ADP2440) or 8-bit, 1GS/s, 200+MHz bandwidth (ADP2450) • Dual mode and low latency memory segmentation • Arbitrary waveform generator with 15MHz bandwidth • Freely allocatable deep buffer memory • 16 digital inputs/outputs supporting a variety of communication protocols • Bode plot, dedicated FFT, impedance analyser, bus analyser, data logger and more • Extensive and powerful software support with WaveForms and WaveForms SDK element14 Australia au.element14.com stand C14 The UP Xtreme PTL Edge is a slim computer with an Intel Core Ultra Series 3 CPU: • DDR5 7200 Dual Channel SODIMM × 2, up to 128GB • HDMI × 2, DP × 2 via USB4.0 Type-C • USB 3.2 Gen 2 (Type-A) × 2, USB 4.0 (Type-C) × 2, 2.5GbE LAN × 2 52 Silicon Chip • M.2 2230 E-Key × 1, M.2 2280 M-Key × 2 • Onboard TPM 2.0 • 19V~36V DC input Advantech AMD Ryzen AI Embedded P100 series platforms, based on the latest Zen 5 architecture, deliver up to 12 cores and 24 threads with AVX-512 support, including VNNI and BFLOAT16 for high compute density and accelerated AI performance. Integrated RDNA graphics provides up to 30TOPS via the AMD ROCm ecosystem, supporting up to four 4K/120Hz displays, including a hardware codec accelerator. The XDNA 2 NPU adds up to 50TOPS at lower power, enabling up to 80TOPS total AI performance (approximately 160TOPS dense) within a heterogeneous architecture designed for low latency and power efficiency across Windows and Linux environments. The platform supports DDR5-5600 memory up to 128GB, PCIe Gen 4 ×8, NVMe, HDMI 2.1, DisplayPort 2.1, and USB4, with TDP options from 15W to 54W, operating from -40°C to 105°C. The AMD Ryzen AI Embedded P100 Series boards are validated for Windows 11 LTSC and Ubuntu LTSC. The EdgeAI SDK enables efficient cross-platform AI deployment using AMD Ryzen AI capabilities, while DeviceOn provides remote monitoring, predictive maintenance and centralised device management. Advantech provides a full portfolio of Ryzen AI Embedded P100 Series platforms for diverse EIoT applications: The MIO-5380 is a 3.5-inch single board computer with: • MCIO flexible PCIe extension for GPU cards • EdgeBMC for out-of-band remote management and recovery • USB 4.0 for external MXM GPU and USB Type-C for 100W Power Delivery (PD) The AIMB-2210 Mini-ITX motherboard has: • USB Type-C Alt Mode with optional 100W PD, supporting four independent 4K displays • 5 × USB 3.2, 2 × USB 2.0, 1 × USB-C, 2 × 2.5GBE, 4 × COM ports (optional TTL and CCtalk) • Multiple expansions: PCIe Gen4 × 16, M.2 M-key, and E-key The SOM-6874 is a COM Express Compact Type 6 with: • DDR5-5600 dual-channel SODIMM memory up to 96GB • 4 independent 4K displays with LVDS/eDP and HDMI/ Display Ports • Up to 18 PCIe lanes for high-speed connectivity • Multiple I/O expansion: up to 18 PCIe lanes, 2.5GBE LAN, USB 3.2, USB 2.0 The EDGE+ VPR-7P132 Mini-ITX embedded motherboard is a powerful combination of AMD’s Ryzen AI Embedded V4526iX processor (Zen 5 CPU, RDNA 3.5 GPU, 50+ TOPS XDNA2 NPU) with AMD’s Versal AI Edge Gen2 VE3558 adaptive SoC (world class programmable logic, ARM CPUs and AI engines). It supports dual 4K displays, 10GbE, M.2 WIFI, SSD storage, and USB interfaces to offload the Versal adaptive SoC of non-time critical functions. Schurter’s (schurter.com/en) EKO series of fuses is engineered for demanding highvoltage environments, offering protection up to 1000V DC (and 1250V AC for selected models) and current ratings from 50A to 1100A. With a breaking capacity of up to 50kA DC, these square-body fuses deliver safety and reliability. Schurter’s new Pyrofuse-APO series sets a new benchmark for safety. Unlike conventional Australia's electronics magazine siliconchip.com.au fuses, the APO Fuse operates actively. In the event of a short circuit or accident, the control unit sends a trigger signal to an integrated micro gas generator. Within milliseconds, the generator produces a high pressure that drives a piston to mechanically sever the solid copper busbar. The resulting arc is safely suppressed in a dedicated extinguishing chamber. The outcome is complete galvanic isolation in less than two milliseconds (as fast as 0.9ms). The new ARO fuses from Schurter provide robust protection for HV applications, integrating seamlessly into charging cables and connectors. Rated voltage: 250V AC; rated currents: 16A, 32A and 63A; breaking capacity: 50kA. The innovative surface-mount USE 2410 fuse from Schurter is a quick-acting F fuse in the 2410 footprint, designed for 125250V AC and 86-125V DC. With a temperature range from -55°C to 125°C, it is suitable for demanding conditions. It has a breaking capacity up to 200A and precise tripping. The compact form factor saves space. The new Schurter USL 0603 low-current fuse has an extended creepage distance of 1.1mm (pad-to-pad), meeting the requirements of IEC 60079-11 for 60V DC applications. It is one of the few fuses in the 0603 format that can be used in ATEX applications, such as in the oil and gas industry, chemical processing or mining. The Schurter MSM II mechanical switch family is growing, with a variant that uses a common anode to control the RGB LED illumination. This combines the familiar, robust mechanics with visualisation technology for clear feedback, easy integration, and maximum reliability in control and operating solutions. The Schurter EDC (Electronic Direct Current) switch was specifically engineered for the reliable switching of direct current in compact systems. It combines the mechanical precision of a microswitch with integrated power electronics, making it completely arc-free. When the contact is opened, the integrated electronics detect the disconnection process at an early stage and interrupt the current in a controlled manner before an arc can occur. The MSS-IO is based on the successful Schurter MSS electronic switch, which has been expanded to include an IO-Link module. Instead of capacitive technology, a precise change in electrical resistance is used for switch detection; sensitive enough to detect the smallest changes in pressure, robust enough for industrial series processes. Emona Instruments Pty Ltd emona.com.au stand B2 Established in 1979, with a head office in Sydney and branch offices in Melbourne, Brisbane, Adelaide and Perth, Emona Instruments Pty Ltd is a high-tech engineering company specialising in electronics, electrical, education and additive manufacturing equipment. Rigol Technologies, represented in Australia by Emona Instruments for over 20 years, are launching three new series of high-performance test instruments at Emona’s display at Electronex 2026. Rigol’s new DNA5000/6000 series vector network analysers (VNA) bring network analysis to every engineer’s test bench. They provide a frequency range from 5kHz to 26.5GHz, siliconchip.com.au Rigol's new DNA5262 and DNA6264 vector network analysers support two or four test ports and deliver high-performance RF component characterisation with powerful S-parameter measurement capability. Rigol’s new RSA6000 series real-time spectrum analysers offer bandwidths up to 26.5GHz. Featuring up to 200MHz real-time bandwidth, low phase noise and advanced analysis modes, they capture transient signals and complex interference efficiently for R&D, wireless, EMI and compliance testing applications. Rigol’s MHO900 series high-resolution digital oscilloscopes combine portability with powerful mixed-signal performance. Offering up to 800MHz (1GHz special edition) bandwidth, 4GSa/s sampling, 12-bit resolution and deep memory, they deliver precise signal visibility, fast waveform capture and advanced analysis. Emona’s Electronex 2026 display will cover oscilloscopes, generators, power supplies and EMC test equipment through to our range of 3D printers and additive manufacturing solutions. The latter range from prototyping in composites through to production-scale printing in thermoplastics and metal. Fibocom Wireless Inc fibocom.com/en/ stand D36 Fibocom’s LE271-GL is a global LTE Cat.1 bis module offering single-SKU worldwide connectivity for IoT devices. Its compact 17.7 × 15.8mm design is pin-compatible with Fibocom’s MC661, LE270 and LE37X series. Supporting both FDD-LTE and TDD-LTE bands, LE271-GL ensures global frequency coverage. The module is built on an OpenCPU architecture and Australia's electronics magazine May 2026  53 ISO13485:2016 certifications and exports to Southeast Asia, Australia, Europe and the USA. Globalink Electronics (S) Pte Ltd https://globalink-e.com achieves registration in under 3.5 seconds. With ultra-low power consumption, its microamp-level sleep current makes it ideal for asset tracking, IP cameras, new energy systems and consumer electronics. It has rich features such as eSIM, dual-SIM, LBS + Wi-Fi positioning, and multiple IoT protocols. The Fibocom LE270-EU delivers exceptional power efficiency and stability for IoT applications across Europe. It achieves as low as 2.5µA in PSM mode and under 100µA in the IDLE state. Even in TCP keep-alive scenarios with a one-minute heartbeat, the average power consumption remains below 2mA. Fibocom’s SC126-EAU module: • Comes with a built-in 64-bit Arm Cortex-A53 quad-core processor at up to 2.0GHz • Supports dual Image Signal Processors and multi-channel camera input • Support up to a 1080p <at> 30FPS display and 1080p <at> 30FPS video recording • Is equipped with the latest Android operating system, allowing long-term lifecycle usage • Planned multiple regional versions for global AloT applications Fibocom’s AI Lawn Mower Terminal features: • Autonomous navigation: AI-powered path planning and obstacle detection for precise and safe mowing • Real-time monitoring: track mower status, location and battery levels remotely via mobile or cloud platforms • Smart scheduling & control: set mowing schedules, adjust cutting modes, and receive notifications anywhere • Energy Efficiency: optimised operations for longer battery life and reduced energy consumption • Seamless integration: connects easily with smart home ecosystems and IoT platforms Finenet Electronic Circuit Ltd www.finenetpcb.com.cn/?lg=en stand A32 Founded in 2000, Finenet Electronic Circuit Ltd is one of the largest integrated solution providers in the high-tech PCB manufacturing industry, with a monthly production capacity of 50,000m2. The company integrates production, sales, and service, with its main products including single-sided, doublesided, multi-layer, HDI, impedance-controlled, metal base (aluminium substrate), press-fit and flexible PCBs. Surface finishes include lead-free HASL, ENIG, chemical tin and OSP, serving industrial, automotive, consumer electronics, lighting and power applications. T h e co m p a n y has recognition as a Guangdong– Hong Kong Clean Production Partner. Finenet has achieved UL, IATF16949:2016, ISO9001:2015, ISO14001:2015, and 54 Silicon Chip stand A9 Globalink Electronics is an established EMS service provider with fully integrated manufacturing facilities in China. Its services include design verification, sourcing, procurement and final assembly, including the production of buzzers, transducers and switches. Glyn Pty Ltd glyn.com.au stand A20 Onomondo provides IoT connectivity infrastructure that eliminates the cost and complexity of traditional telecom systems. Our software-defined core network integrates directly with 680+ carriers in 180+ countries, giving programmable control over connectivity settings and the ability to deploy globally without multiple regional contracts. At Electronex, we will demonstrate our SIM management platform, packet-level troubleshooting, and live SoftSIM-enabled devices. TDK’s compact GUS series of single-output AC-DC industrial power supplies are available with 12V, 24V, 36V and 48V outputs in an economic, compact footprint and can deliver up to 350W, 600W or 1000W. GUS350 is convection-cooled, while GUS600 and GUS1000 have an integral cooling fan. Remote on/off is an option for all models. Efficiency of up to 95.5% (model dependent) is possible. Compact HWS3000G AC-DC power supplies can deliver 1500W with a low-line input voltage of 85-132V AC and 3000W at high-line 170-265V AC. The HWS3000GT is rated at 3000W with a three-phase input voltage of 170-265V AC. With nominal output voltages of 24V, 48V, 60V and 130V, the output voltages and currents are fully programmable (CV/CC) from zero up to their maximum rating using a serial RS485 interface (MODBus protocol), 1-5V or 4-20mA signals. Up to three units can be connected in series and/or ten units in parallel. The DUSH 960W uninterruptible power supply for DIN rail applications has wide input and output voltage ranges of 10-60V DC in and 10-58V DC out. It can be deployed in a multitude of applications such as industry automation, plant engineering, building control systems, test & measurement, or information & communication technology. The D1SE series is a cost-effective and reliable power supply, with outputs of 120W, 240W and 480W and AC or DC operation. They are equipped with push-in terminals and, for applications in challenging environments, models with coated PCBs are available. The DDSM series of DC-DC converters offer 120W and 240W output powers in a compact, lightweight design with wide input and output ranges. The series is fully digitally controlled; the 7-segment display shows precise system values, status and Australia's electronics magazine siliconchip.com.au alarm codes. It can be operated directly via three push buttons. The DDSM can be operated with the PowerCMC software tool using the Modbus over USB connection. Suitable for 19-inch rack mounting, GENESYSAC (GAC) programmable power sources have a very high-power density. The series offers power levels of 2kVA and 3kVA (1U) or 6kVA a n d 9 k VA (3U), with the possibility of paralleling units to increase the output power. Its auto-ranging power output can be single-phase or three-phase, with an adjustable voltage from 0V to 350V AC and ±500V DC (GAC-PRO models). The frequency range is 16Hz to 1.2kHz (up to 5kHz for the GAC-PRO). Remote programming methods include built-in LAN, USB, RS232 and RS485. The GAC-PRO models include the realtime analog control functionality necessary for complex test scenarios. The series has a full-colour, multi-language LCD touch panel display and a software GUI interface. Optional avionics and IEC test libraries are available. Hawker Richardson https://hawkerrichardson.com.au stand C28 Our complete turnkey SMT solutions bring together world-class equipment, intelligent automation and software-driven process control into a fully integrated production environment. From equipment supply to commissioning and ongoing support, each SMT line is engineered to deliver consistent quality, high throughput and repeatable manufacturing: • High-performance pick and place systems for speed, accuracy, and flexible component handling • Inline quality control, incorporating SPI, AOI and X-ray inspection to detect defects early • Advanced reflow systems delivering stable thermal profiles and consistent soldering results • Precision rework stations for BGA, QFN, CSP and finepitch components At the heart of every turnkey SMT line is YSUP intelligent SMT software. YSUP connects all machines into a single, coordinated workflow through machine-to-machine (M2M) communication with: • Closed-loop feedback that automatically feeds inspection results back upstream to prevent defects from progressing down the line • A visual data editor to simplify programming, reduce setup time, and minimise operator error • Real-time dashboards providing live visibility of performance, defects, and line efficiency • Intelligent algorithms that automatically detect and correct issues such as component polarity Ya ma ha ’ s n e w Y R M placement machine is designed for odd-form and specialised components that standard SMT heads struggle with. Odd-form components (such as large connectors, transformers, and sockets) historically required manual assembly. siliconchip.com.au High-capacity heads like the LM head can handle them automatically, improving yield and reducing labour costs. Modern EVs rely on heavy-duty, high-current connectors and power modules that standard SMT heads cannot lift or place. The rapid expansion of generative AI has increased demand for large, high-pin-count components such as BGAs and FPGAs, which require the precise force control and handling capability of LM-class heads. The LM head’s ability to mount parts up to 500g, 90 × 139mm in size and 40mm in height, along with other heads for smaller parts, allow for this extreme range. The LM Head has 100N placement-force management for press-fit parts, and vision software recognising up to 20,000 BGA balls. Now exclusively represented in Australia and New Zealand by Hawker Richardson, PDR brings world-leading rework capability to local electronics manufacturers and repair specialists. Designed for today’s increasingly complex PCBs, PDR Focused IR systems deliver precise, repeatable rework without thermal shock or unnecessary stress to surrounding components: • Focused infrared heating targets only the component being reworked, ensuring controlled, stress-free removal and replacement of BGAs, QFNs, CSPs, LEDs and leadless devices • PC-based closed-loop thermal management precisely controls both component and board temperatures, delivering repeatable results and protecting sensitive assemblies • Tool-free, gas-free operation with instant thermal response simplifies setup, reduces operating costs and creates a cleaner, more efficient rework environment • From entry-level systems like the IR-E1 to advanced semiautomated platforms, the modular design allows systems to scale as rework complexity and production demands increase Hua Wei Industrial Co Ltd www.hwlok.com stand D33 The new range of TEFZEL (ETFE) cable ties is engineered for applications requiring exceptional chemical resistance, thermal stability and long-term durability. Made from high-performance fluoropolymer material, the product delivers outstanding resistance to extreme temperatures, UV exposure, chemicals and ageing. TEFZEL cable ties maintain mechanical strength and dimensional stability across a wide operating temperature Australia's electronics magazine May 2026  55 range, ensuring reliable fastening performance where conventional nylon ties may fail. The material’s flame resistance and low-smoke characteristics further enhance safety in critical installations. A precision-moulded locking mechanism provides secure fastening while allowing efficient, tool-free installation. These cable ties are particularly well-suited for aerospace, automotive, electronics, chemical processing, and industrial equipment applications, as well as environments exposed to fuels, solvents, or corrosive substances. PA66 nylon cable ties are heat stabilised up to 120°C (248°F). They are UL and CE certified for industrial and professional use: • Internal serrations ensure a secure and positive grip on cables and pipes • Optimised head design delivers high tensile strength while maintaining low insertion force • Available in a wide range of sizes to suit almost any application • Flammability rating: UL94 V-2 • Colours available: black, red IMP Electronics Solutions imppc.com.au stand A24 The new DT035CTFT series of 3.5-inch colour IPS LCD modules features a high-resolution 320 × 480 pixel display. With a super-high-brightness backlight and a wide IPS viewing angle, these displays ensure excellent readability and consistent colour performance in indoor and outdoor environments. Available with an optional capacitive touch panel, this 3.5inch IPS TFT is an ideal LCD for industrial, consumer and medical devices. The DT050CTFT series of 5.0-inch colour IPS LCD modules has an 800 × 480 resolution, offering crisp visuals, wide viewing angles and consistent colour reproduction. Its super-highbrightness LED backlight ensures excellent readability in any lighting condition, including direct sunlight. An optional capacitive touch panel provides responsive, intuitive input for interactive applications. The EEMB high-capacity lithium polymer battery is designed for greater energy density, safer, wide temperature range and high power delivery in ultra-thin, flexible form factors. By optimising electrode structure and materials, the high-capacity batteries achieve higher energy density without increasing size. EEMB ultra-low-temperature battery technology delivers reliable performance in extreme cold environments. From emergency rescue equipment in polar regions and high-end outdoor gear to drone logistics and monitoring systems, EEMB low-temperature batteries provide critical power support and operate reliably in the most demanding conditions. ONBoard Solutions Pty Ltd onboardsolutions.com.au stand C3 HumiSeal 1B59 SEC is a synthetic rubber-based conformal coating designed to enhance sharp edge coverage while providing superior moisture and environmental protection. This latest formulation optimises edge retention, ensuring uniform thickness across complex geometries. It is fast-drying 56 Silicon Chip The HumiSeal 1B59 SEC coating shown wet (left) and dry (right). and easy to apply, suitable for spraying, dipping and selective coating processes. Its superior moisture and chemical resistance provide robust environmental protection against harsh conditions. The UV tracer allows for easy inspection under UV light. Ideal applications for HumiSeal 1B59 SEC are high-reliability electronics, automotive and aerospace PCBs, and industrial and consumer electronics requiring moisture resistance. PROMOSOLV DR3 from Inventec Performance Chemicals is a non-flammable, low-GWP solvent designed as a highperformance replacement for 3M Novec 7030 in light-duty cleaning and rinsing applications. It delivers exceptional cleaning performance with very low surface tension (13.6 dynes/cm), enabling deep penetration into tight geometries and complex assemblies. It is thermally and chemically stable in use, offering short cleaning, rinsing and drying times in both mono-solvent vapour phase and co-solvent processes. With no flashpoint, PROMOSOLV DR3 supports safer workplace operation while aligning with evolving environmental regulations. The product is compatible with all metals and alloys, including sensitive substrates, and demonstrates strong material compatibility across a wide range of applications. Photonics’ laser depaneling systems deliver highprecision, non-contact separation of PCBs, enabling manufacturers to achieve clean, burr-free edges without mechanical stress. Traditional mechanical depaneling methods can risk board damage, delamination, or component stress. Photonics’ laser-based approach uses a controlled, high-energy beam that precisely cuts the substrate according to programmed patterns. The system utilises advanced laser optics and motion control to produce repeatable results with a range of materials, from standard FR-4 to high-performance laminates and flexible substrates. Non-mechanical depaneling eliminates tool wear, reduces particle generation and minimises post-process cleaning. With integrated vision systems and programmable cut paths, the modular architecture enables seamless integration into SMT and box-build lines. The MBtech NC25 precision cleaning system is designed to address a wide range of contaminants, including flux residues, particulates, oils and process soils. Built around a robust wash-rinsedry architecture, it uses carefully controlled spray dynamics and chemical management to achieve Australia's electronics magazine thorough cleaning across complex assemblies, fine geometries and mixed-technology boards. The system’s modular design allows flexible configuration to match customer process requirements, including ultrasonic enhancement and rinse stage optimisation. PCBWay pcbway.com stand A10 PCBWay’s transparent PCB is manufactured using a halogen-free transparent resin substrate. Unlike traditional glass-based substrates, it delivers high optical clarity while maintaining excellent mechanical and thermal performance. The material is lightweight, heat-resistant, and impactresistant, making it suitable for advanced applications where both transparency and reliability are required. Depending on board thickness, transparent PCBs can be combined with flexible displays and are well suited for innovative products such as transparent displays, transparent televisions and smart devices. The material is fully compatible with standard FR-4 processing, allowing direct integration into existing production lines without additional investment, ensuring high manufacturability and process adaptability. Transparent PCBs have outstanding resistance to yellowing, chemicals, heat and CAF (Conductive Anodic Filament), meeting demanding design requirements for high reliability and superior optical performance. They have low moisture absorption and are suitable for leadfree reflow soldering, with high impact resistance, superior CAF resistance and reliable through-hole performance and solderability. Transparent PCB specifications: • Flammability rating: 94V-HB • Maximum operating temperature: 130°C • Layer count: 1-6 layers • Base material: transparent FR-4 • Solder mask: transparent • Board thickness: 0.002in (0.05mm) to 0.080in (2.0mm), suitable for both small and large formats • Copper weight: 1/3oz to 5oz, available for multi-layer and double-sided boards • Film format: roll material or small panel formats • Glass cloth (prepreg): 106, 1080, 2116, 7628 or customised upon request • Minimum trace/spacing: 4mil • Surface finish: immersion gold, ENEPIG or OSP • Silkscreen: custom colours available Rohde & Schwarz (Australia) www.rohde-schwarz.com/au stand C8 Rohde & Schwarz will be back at Electronex in 2026 with a wide range of test and measurement products to demonstrate, including the new generation R&S MXO 3 Oscilloscope series: Fast. Precise. Compact. Key facts: • Unmatched performance with bandwidths from 100MHz to 1GHz • World’s fastest oscilloscopes with 4.5 million waveforms/s and up to 99% real-time capture • Industry-leading architecture with 12-bit ADC and 18-bit HD mode siliconchip.com.au • The most compact eight-channel oscilloscope with MSO, generator and large 11.6-inch display • Up to 50,000 FFTs/s with independent time and frequency settings The MXO 3 Series put big capabilities in a small package. Enjoy unmatched performance to quickly and easily gain expert understanding of your device under test. Powered by next-­ generation MXO technology, the oscilloscope delivers fast and precise measurements in a small package. Instantly see more signal detail with the world’s highest acquisition rate of up to 4.5 million waveforms per second and real-time signal capture of up to 99%. Capture every detail with clarity and confidence thanks to 12-bit ADC resolution at all sample rates, enhanced 18-bit HD mode, advanced digital triggering and 125Mpoints of standard memory. Save space without sacrificing usability: enjoy the brilliant 11.6-inch full HD display and seamless integration into any setup with just a 5U rack height across all models. The MXO 3 Oscilloscope has unmatched performance in both time and frequency domain debugging and testing. Semitech Semiconductor semitechsemi.com stand D6 Semitech Semiconductor, a proudly Australian semiconductor company, sells its flagship SM2400 power line communications chip for smart grids, stadium lighting, airport runway lighting, semi-trailers, smart building systems and mining drill rigs. Semitech’s market-leading chips are designed in Australia with wafers manufactured by TSMC. Semitech has teamed up with Texas Instruments to offer the latest G3 Hybrid network architecture to the global smart grid market. Smart Grid networks modernise traditional electricity grids by integrating two-way digital communication. They support applications such as advanced metering infrastructure (AMI), demand response, distributed energy resources (DERs), fault detection and distribution automation. Power line communication (PLC) is uniquely positioned in smart grids by using the existing medium-voltage (MV) and low-voltage (LV) electricity distribution networks as the communication channel, eliminating the need for new cabling, while overcoming the shortcomings of wireless communication. Utilising modern signal processing and mesh networking techniques, G3 Alliance developed the G3 PLC and G3 Hybrid standards to provide a ubiquitous and reliable network architecture with unprecedented reach without requiring new infrastructure investment. G3 PLC networks have been deployed in over 60 countries, with over 1 million devices connected, and are rapidly expanding. Semitech offers a best-in-class G3 PLC solution built on the versatile SM2400A PLC modem, designed for advanced narrowband PLC protocols: • Advanced dual-core architecture for low-cost and power efficiency • Multi-protocol support, including G3 PLC and G3 Hybrid • Superior noise resilience with advanced preamble detection and <20dBµV sensitivity Australia's electronics magazine May 2026  57 • Certified G3 stack supporting full OFDM-based PHY, MAC, and 6LoWPAN ASL • Built-in security with an integrated AES-256 security engine • High-Speed PLC with data rates above 600kbps • AC and DC power line compatible • Global frequency band compatibility, including CENELEC (Europe), FCC (North America) and ARIB (Japan) • Future-proof software-defined performance with remote firmware updates • Flexible integration options, including external flash or host-loaded modes and a wide range of compatible line drivers • Easy to develop, troubleshoot and prototype, with complete developer-friendly tools and evaluation kits Hybrid networks seamlessly integrate PLC with RF mesh into a single, unified infrastructure. This dual-medium approach improves the network’s robustness and capacity, making the network more resilient even in hard-to-reach locations. In partnership with Texas Instruments, Semitech delivers a G3 Hybrid platform that seamlessly combines PLC and sub-GHz wireless for maximum reach and reliability: • Full integration of TI’s CC1312R wireless MCU and Semitech’s dual-core SM2400 PLC • High-performance sub-GHz wireless MCU for robust, reliable long-range RF communication • Dynamic mesh routing, automatically sensing and selecting RF or PLC communications for ideal connectivity • RF-only mode for battery-powered edge devices; +14dBm RF output power with temperature compensation • Dual media reliability with automated PLC or RF path selection • Seamless networking with full mesh routing across both PLC and RF • Long-range wireless utilising TI’s high-performance MCU for 802.15.4 Shenzhen Cirket Electronics szckt.cn stand C13 The HackRF Pro is an advanced software-defined radio (SDR) for testing and developing modern radio technologies. It operates as a half-duplex transceiver, supporting frequencies from 100kHz to 6GHz, with tuneable ranges up to 7.1GHz and sampling rates up to 20Msps (40Msps in oversampling mode). It features a high-speed USB 2.0 interface with a Type-C connector, SMA antenna connectors and a built-in TCXO crystal oscillator. Compared to its p r e d e ce s s o r, t h e HackRF Pro has a wider frequency range, better RF performance with a flatter frequency The HackRF Pro. Source: r e s p o n s e a n d a www.youtube.com/watch?v=C0W-pYcgHeA power-efficient FPGA replacing the old CPLD. It also offers extended-precision mode with 16-bit samples for low sample rates and half-precision mode with 4-bit samples at high rates. The HackRF Pro enables applications like signal analysis, protocol development and wireless security testing. Its opensource nature, portable design, and backward compatibility make it a versatile and cost-effective solution for exploring 58 Silicon Chip radio communication systems. Shenzhen Cirket company is the biggest HackRF One manufacturer over the past decade. LED PCBAs longer than 1.5m are used in building wall, bridge, shopping mall, road tunnel and some other lighting construction projects. Shenzhen Cirket Electronics Co Ltd has three SMT lines for long PCB assembly. Our solder paste printer can print PCBs up to 1.8m long. We have added additional tracks on both sides of a Yamaha pick and place machine, with a 500mm PCB conveyor between two mounting machines. Each machine can mount components on half of the long PCB. As the board is long, the pad position tolerance is larger than for smaller PCBs. Thus, the PCB factory needs to provide high-precision boards. The stencils must use good-quality steel sheet to remain stiff enough. A strong and stable solder paste printer ensures all solder paste is in the correct locations. Our factory has extensive experience in this process. Our factory, Shenzhen Cirket, has mastered complex PCBA processes. One recent production involves a 10-layer PCB with Isola 370HR material, specifically processed to maintain structural integrity at a high Tg of 180°C. A key challenge we managed is the copper weight distribution, ranging from 0.5oz to 1.5oz across different layers, ensuring consistent plating quality and thermal performance. For interconnect reliability, we utilised advanced copperfilled thru-via technology. These vias are plated over to create a perfectly flat surface, critical for high-density contactor areas. An ENEPIG surface finish provides a superior, flat interface that is exceptionally friendly to fine-pitch BGA soldering, eliminating the risks of ‘black pads’ and enhancing joint strength. The BGA ball spacing for this board is 0.25mm. We use high-reliability Alpha tin with 3% silver as the solder paste. Too active solder paste can cause short circuits very easily with close BGA ball spacing. Thus, a proper oven temperature chart is very critical. Silvertone Electronics silvertone.com.au stand C26 The VSG200 20GHz vector signal generator features a low phase noise, agile local oscillator with a 200µs switching time, enabling frequency-hopping spread-spectrum testing. A dual 14-bit DAC runs at 2× or 3× the I/Q symbol rate, using digital oversampling to provide a flat, clean baseband. A digitally adjustable internal VCTCXO ensures frequency errors are kept to a minimum over temperature, o r a n e x t e r na l 10MHz input may be used for 0ppm frequency error. Australia's electronics magazine siliconchip.com.au R&S®ESSENTIALS SMALL IN SIZE, BIG IN IMPACT. The new MXO 3 oscilloscope. Fast. Precise. Compact. With a combination of features that rival much higher-class oscilloscopes, in a deceptively small package, the MXO 3 ensures you catch rare signal anomalies, debug complex issues, can take it wherever your work demands and still have plenty of time to high-five your entire team. Explore more • Available modulation types: LTE, 802.11a/n/ac/ax, Bluetooth LE, custom OFDM, 16/64/256/1024-QAM, 2/4/8/16PSK, 2/4/8/16-FSK, ASK, GMSK, AWGN channels, ramp/chirp, stepped sweep, multi-tone, pulse, FM, AM, CW, arbitrary/ custom • Digital modulation impairments/effects: custom channel response, AWGN, sampling rate error, frequency and level offset, I/Q offset, spectrum inversion The PCR4200 four-channel phase-coherent receiver is a high-performance, 100kHz to 20GHz, four-channel phase coherent receiver, streaming I/Q data over a VITA 49 interface. Each channel on the PCR4200 may be configured as a phasecoherent channel using the high-performance shared local oscillator (LO), or independently tuned using that channel’s dedicated LO. Any single channel may be configured to provide swept spectrum data at up to 200GHz/s. • Streams 40MHz bandwidth per channel over 10GBE SFP+ • Built-in sub-octave preselectors from 45MHz to 20GHz • Noise figure: 10dB typical at 2GHz • Calibrated I/Q data • Ultra-low phase noise: -136dBc/Hz 10kHz offset from 1GHz centre frequency • Internal GPS • 110dB dynamic range • Independent channel configuration • Up to 16 phase-coherent channels Applications include simultaneous multi-band spectrum monitoring, emitter detection and geolocation, multi-channel transmitter testing, SIGINT/COMINT/ELINT, drone detection and MIMO channel testing. Stars Microelectronics starsmicro.com stand D3 Stars Microelectronics is the only Thailand-based company that delivers world-class EMS, SMT, OSAT, advanced IC packaging and advanced photonics solutions, serving industries including microelectronics, telecom, industrial automation, professional audio/video, automotive RF & power electronics, medical devices and clean energy. Our commitment to world-class standards, certified facilities and strict quality assurance means that every product we deliver is crafted to exceed customer expectations every time. Leveraging Free Trade Zone advantages and supported by global offices, we provide seamless, reliable and cost-effective solutions that strengthen your competitive edge in the global market. Suba Engineering Pty Ltd suba.com.au stand A27 The new SubaScope Ultimate has a CMOS camera that includes multiple output modes (HDMI, WiFi, USB 3.0 and network). The camera uses an ultra-high-performance CMOS sensor. It can be directly connected to an HDMI display or to a computer via WiFi or USB and images and videos can be saved directly for on-site analysis and subsequent research. The user can directly control the camera hardware with the software ToupView or ToupLite. 60 Silicon Chip SubaScope Ultimate is enhanced with an embedded ARM core. The camera has a built-in auto focus system, which can realise the best auto focus specification areas of the sample. Some key features are: • 16MP Sony CMOS sensor • 4K / 1080p auto-switching according to monitor resolution • USB flash drive for captured image and video storage, supporting local preview and playback • Autofocus supporting Canon EF-mount lenses – the SubaScope is the only digital microscope on which you can change from far distance to close distance by changing the Canon camera lens • Embedded XCamView for control of the camera and image processing, supporting automatic edge finding and measurement functions • ToupView and ToupLite software for PC • iOS and Android applications for smartphones or tablets Switches Plus Components switchesplus.com.au stand C4 Compact HMI controls can have a large impact while saving space on panels, armrests, and wireless, autonomous devices. OTTO Controls’ smaller joysticks, thumbwheels and paddle switches offer reliable, precision management for many functions. OTTO’s JHLN single-axis joystick is perfect for space-­constrained operator cabs due to its narrow and bottom-mount construction. Select from friction hold or return-to-centre actuation and between five handle types. JHT mini joysticks enable spot-on movement; they are commonly used in military, aerospace, medical and heavy equipment applications. Z-axis models also feature a 60° rotating knob on the top. Single- and dual-axis finger joysticks have various button styles, such as bat handles or concave, to give the operator the optimal tactile feel. Sealed Hall-effect thumbwheels with a knurled wheel or paddle wheel are great choices for grips and panels. Hall effect paddle joysticks come with three lever style and output options. Australia's electronics magazine siliconchip.com.au RAFIX’s MICON 5 and RACON series of tactile switches deliver precisionengineered solutions for high-reliability electronic applications. Designed for direct PCB mounting, these compact components combine defined actuation characteristics with a long mechanical lifespan and stable electrical performance. The MICON 5 family is optimised for precise tactile feedback and consistent switching behaviour over millions of cycles. Gold-plated contacts provide low and stable contact resistance, ensuring reliable signal transmission, even in lowcurrent circuits. The SL version is rated for up to ten million actuations. MICON 5 SAFETY is ideal for safety-related systems, integrating two electrically isolated, potential-free contacts within a minimal footprint to enable redundant signal paths for functional safety architectures. The RACON 8/12 ST series has been developed for operation in harsh environmental conditions. With sealed designs up to IP67 and an operating temperature range of -40°C to +125°C, they are ideal for automotive, industrial and outdoor electronics. Their robust housing design, defined switching forces and SMT compatibility support automated assembly processes and ensure longterm performance under mechanical and environmental stress. The RAFIX 22 FS+ from RAFI is a modular control and signalling system designed for industrial machinery, automation equipment and control panels. Based on a standardised 22.3mm mounting hole, the RAFIX 22 FS+ enables the consistent integration of push buttons, selector switches, key-lock switches, emergency stop actuators and signal indicators within a unified design concept. R A F I X 2 2 F S + co m p o n e n t s a re engineered for use in demanding industrial environments. Features such as front panel sealing up to IP65 and IP69K, impact-resistant front rings and durable marking options ensure reliable operation when exposed to dust, moisture and cleaning processes. Illuminated versions with LEDs enable uniform, efficient signalling with high visibility. Techal Solutions techalsolutions.com stand C22 Based in Melbourne, Australia, TECHAL SOLUTIONS specialises in providing state-of-the-art SMT electronic production equipment, assembly automation solutions, plus spares, consumables and accessories. 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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 siliconchip.com.au Australia's electronics magazine May 2026  61 SC7657 Kit ($45 + postage): includes everything in the parts list a compact and simple ¬C Meter by Andrew Woodfield This little LC meter uses just 20 parts and delivers accurate results across a wide measurement range. Importantly, no costly or hard-to-find precision parts are needed. Compact, lightweight, inexpensive and easy to build Inductance range: <10nH to about 100mH Customer 3D-printed case M 62 Silicon Chip Capacitance range: <10pF to about 1μF Typical accuracy: ±2% any years ago, I built my first LC meter using the Atmel 89C8051 microprocessor. It worked very well, but it drained batteries fast. This was not really a problem because I rarely used it for more than a few minutes at a time. When I moved to another country several years later, I designed my own LC meter using one of the Microchip ATtiny microcontrollers and a twoline I2C alphanumeric LCD screen. It was powered by a standard 9V battery via an LP2951 low-dropout voltage regulator. While it drew very little current, unfortunately, just when I most wanted to use it, the 9V battery would require replacement. Returning home, I modified it to use a single 1.5V AA alkaline cell and a tiny boost converter. The AA battery version had a surprisingly good life. One reason was the complete absence of relays in the design. Some LC meters use anywhere from one to four (!) relays. This new version quickly became my ‘go-to’ LC meter. It was also borrowed periodically by friends because of its accuracy and ease of use. I was asked if I could design a smaller, cheaper, easier-to-make version. While I had expected the change to a single AA cell to bring about a reduction in the overall size of the LC meter, it was still constrained by the size and shape of the alphanumeric LCD Measures capacitor and inductor values Power supply: single AA cell screen and the added boost converter. That LCD was also a relatively costly device. These factors, along with the perceived need for 1% tolerance parts for calibration, were all seen as barriers by potential builders. The wide availability of smaller, inexpensive 0.91-inch OLED screens was the catalyst for a further redesign. It offered the opportunity to further reduce the size, cost and parts count. The product of this latest redesign is the LC meter described here. By finally doing away with any regulator and using any convenient USB-C 5V power supply, the LC meter has now been reduced to the volume roughly of a pair of AA batteries. Note that the 2-pin USB-C connector used is not standards-compliant and may not work with all USB-C/USB-C cables and power supplies. It should work with all USB-C/USB-A cables. A little LC meter theory Almost all LC meter designs use an LC resonant circuit in a simple oscillator. These typically operate around 500kHz (the ‘reference frequency’) when no actual inductors or capacitors are being measured. A 100μH inductor and a 1nF capacitor are the typical resonant circuit values used. When an unknown capacitor or inductor is added to this resonant circuit, the oscillator frequency drops. By Fig.1: an LM311 comparator is commonly used in the LC measurement oscillator in electronics most LC meters, but it requires a relatively high number of parts. Australia's magazine siliconchip.com.au measuring this reduction, the value of the unknown part can be determined. One variation of this approach uses two capacitors in the basic tuned circuit. The additional frequency measurements were claimed to give more accurate results. However, this additional capacitor proved unnecessary. Even the value of the reference inductor can be ignored when calculating the value of the capacitor or inductor being measured. For those interested in the details, refer to the panel titled “Only one capacitor is required”. Only one capacitor is required A simple LC resonant circuit, shown in Fig.a, lies at the heart of the LC meter. It sets the output frequency of the meter’s 74HC04 inverter-based oscillator. This LC circuit resonates at a frequency determined by the values of L and C: f1 = 1 ÷ (2π√LC). If another capacitor, Cx, is added in parallel with this circuit (Fig.b), the oscillator frequency falls to a lower frequency, f2 = 1 ÷ (2π√LC + LCx). If the value of capacitor C is known, we can calculate the value of the unknown capacitor, Cx, from the original frequency f1 and the new, lower, oscillator frequency f2 using this formula: The LC meter backstory Most current LC meter designs are derived from the original AADE design published by Neil Heckt in Electronics Now magazine, June 1996, or variations based on a later design and software by Phil Rice, VK3BHR. However, the approach used in these LC meters is actually much older. For example, the Tektronix model 130 LC meter first released in 1959 (June-­August 2020; siliconchip.au/ Series/346) used the same method, although using an analog display. Some thirty years later, Bill Carver, K6OLG, used a FET-based oscillator and some Pascal software in a design described in Communications Quarterly magazine in Winter 1993 to achieve a similar result. But it took until 1998 for these ideas to be integrated into Neil Heckt’s compact design, complete with a digital display. Fig.a: a simple parallel resonant LC network. This means that the unknown capacitor value may be calculated directly using the value of the reference capacitor (C) and the two oscillator frequencies (f1 and f2). It is also possible to measure an unknown inductor with the LC circuit. In this case, the unknown inductor (Lx) is added in series with the existing inductor L, as shown in Fig.c. The frequency again falls from f1 to f2. Fig.c: adding inductance in series with the original L also lowers the resonant frequency. Design optimisation The oscillator at the heart of many of these designs uses a fast comparator such as the LM311 (see Fig.1). While it can work very well, it uses a relatively high number of parts. Also, at times, I’d found the LM311 hard to find and/ or relatively expensive. We’ve also heard from some people who’ve built these circuits and they fail to oscillate. Swapping the LM311 usually fixes it. Few details were typically given about the best parts to use for the main oscillator components (L1 and C1 in Fig.1). A few builders suggested that this oscillator required low-ESR coupling capacitors. Several internet forums mentioned problems with specific types of inductors. Details based on measurements and testing, however, were scarce. Since I wanted to identify the best parts to use for L1/C1, I also used this siliconchip.com.au Fig.b: adding more parallel capacitance (externally) lowers the resonant frequency. Once again, this equation calculates the value of the unknown inductor Lx based only on the value of the two resonant frequencies, the first (f1) with only L and C in circuit and the second (f2) with the addition of the unknown inductor. The only other parameter needed is the value of the reference capacitor, C. Therefore, the value of unknown capacitors and inductors can be measured by knowing the value of just the reference capacitor, C. opportunity to look at a simpler and less costly alternative oscillator. Based on some previous work with 74HC04 CMOS hex inverters in oscillators, this device looked like a good candidate. This choice might address another problem. The LC meter’s accuracy relies on a very accurate clock source. Australia's electronics magazine Most LC meters use the chosen microcontroller’s internal oscillator and an external crystal. Unfortunately, by opting for a small 8-pin ATtiny processor in my LC meter, only one pin remained free for an external clock. That meant I had to use a separate external crystal oscillator. May 2026  63 Initially, I used a discrete single-­ transistor oscillator based on a Jim Williams design (in Linear Technology Application Note 12, October 1985) which also offered temperature compensation, but this took more parts as well as PCB real estate. The availability of several spare gates in the 74HC04 allowed me to build a suitable crystal oscillator with just a crystal and three extra passives. Fig.2: the value of MKT capacitors can change significantly with frequency, making them a poor choice for an LC meter reference capacitor. Source: Ostrava MKT datasheet. Resonant circuit components Since the reference frequency is determined almost entirely by the value of the inductor and capacitor used, it is important that their values are stable during any measurement(s). In practice, as with any analog oscillator, the reference frequency changes slightly with changes in temperature. It’s a sensitive circuit. Simply switching on the LC meter and passing the tiny current through the LC circuit as it starts oscillating results in a slight change in temperature. One measurement method can largely negate the impact of this drift. By measuring the reference frequency prior to connecting the unknown part, then quickly measuring the oscillator’s frequency once the part is connected, the impact of drift can be mitigated. The best solution, however, is to select stable components. The reference inductor and capacitor should ideally be perfectly stable with temperature. An inductor wound on a high-Q ferrite toroid might appear ideal. However, the typical temperature coefficient (TC) for this type of inductor is up to 10,000ppm/°C (!), making it unsuitable. Similarly, a silver mica capacitor would appear the ideal choice for the reference capacitor. These have excellent temperature stability and, while relatively expensive, ±1% tolerance parts can be obtained. My tests showed that the optimal solution is to balance the TCs of the reference capacitor and inductor. This is a similar approach to that used in legacy analog RF variable frequency oscillators (‘VFOs’). After testing a variety of inductors, this design uses a cheap and widely available axial choke inductor and a polystyrene capacitor. The axial choke has a positive TC of about 300-500ppm/°C, while the polystyrene capacitor has a TC of around -150ppm/°C. While it’s tempting to suggest substituting a polyester (-200ppm/°C to 600ppm/°C) or Mylar (-300ppm/°C) capacitor, they can suffer from changes in capacitance with frequency, especially the MKT types that come in rectangular packages. Some polyester/Mylar capacitors may be suitable, but it’s hard to know which without checking the data sheets. For example, one manufacturer’s specifications for an MKT capacitor (Fig.2) shows a variation in capacitance of around 4% from 1kHz to 1MHz. Circuit details The resulting circuit is shown in Fig.3. It is built around two inexpensive devices: the 8-pin ATtiny85 microcontroller and a 74HC04 CMOS hex inverter. Three inverters in the 74HC04 provide the measurement oscillator and buffer. It uses less current and requires fewer parts than the more familiar LM311-based oscillator. This is configured as a Franklin oscillator using two of the gates of Fig.3: an inexpensive CMOS hex inverter (74HC04) is used in the two oscillators required in this LC Meter, while a Microchip (Atmel) 8-pin ATtiny85 calculates the value of the unknown inductors or capacitors and drives the OLED display. 64 Silicon Chip Australia's electronics magazine siliconchip.com.au the 74HC04 (IC1f & IC1e). The third gate (IC1d) buffers the oscillator and connects the output to the ATtiny85 microcontroller (IC2). Relay switching is avoided through the use of a simple two-pole changeover slide switch, S1. Contacts on this switch also tell the processor whether the user wants to measure inductance or capacitance. It’s simple, inexpensive and reliable. It also has the considerable advantage of drawing no current. The Microchip ATtiny85 8-pin microcontroller with its 8kiB of internal flash program memory is the brains of the meter. It measures the frequency of the LC reference oscillator, monitors the user LC mode selection and calibration switch inputs, and drives the OLED display. The software is written in Bascom-­ AVR, and it consumes 99% of the 8kiB memory, although a few hundred bytes are consumed for the arguably cosmetic ‘splash screen’ image that’s shown when power is applied. There are three further inverters available in the 74HC04 used for the crystal oscillator circuit. HCxx inverters are not usually considered suitable for crystal oscillators. However, by configuring these gates again as a Franklin oscillator with minimal feedback coupling, the resulting crystal oscillator delivered a reliable solution while further reducing the parts count, current drain and cost. Incidentally, this circuit was tested with a variety of 1-30MHz crystals from several sources and it proved quite reliable. Using this circuit with other crystal frequencies for other designs will require a change to the value of the coupling capacitors to ensure reliable operation. Each line in an I2C interface (SDA & SCL) usually requires a pull-up resistor to the supply rail. Usefully, these are already on the OLED module, saving another two parts. This LC meter draws about 25mA during operation. The OLED screen is responsible for about 70% of that. The earlier I2C LCD version drew less than 15mA, but those LCDs are also more expensive and harder to find than OLED displays now. The ±1% reference capacitor Practically every DIY LC meter or capacitor meter design seems to demand one (or more!) ±1% tolerance capacitors, at least for the capacitor siliconchip.com.au Measuring capacitance accurately This simple method can measure capacitor values within about ±1.5%. It requires a lowcost function generator with a low impedance output (eg, 50W), an oscilloscope and a digital multimeter. A frequency counter may be required if your function generator does not have a digital display (and you don’t have one built into your oscilloscope). The measurement setup is shown below. The oscilloscope is used to measure the magnitudes of Vin and Vout. A digital AC millivoltmeter is a better choice if you have one (we’ve published several suitable designs). If the output voltage Vout is exactly half that of the input voltage Vin then C = √3 ÷ 2πfR. Let’s assume the function generator (used as the signal generator) is set to generate a sinewave at about 10kHz. Ideally, the frequency used should allow the resistor value (R) to be accurately measured with at least 3½ digit accuracy using the multimeter, eg, 123.4W or 1234W. Let’s say the capacitor to be measured is labelled “10nF” (although we don’t yet know its precise value), and f = 10kHz. In that case, R = √3 ÷ (2π × 10kHz × 10nF) = 2757W. The nearest standard value is 2.7kW. Reach into your parts bin and take out a 2.7kW resistor, then measure its actual value with the digital multimeter. My old Fluke Model 75 multimeter has a stated accuracy of ±0.7% when measuring resistors, although the typical Model 75 actually had an accuracy closer to ±0.3% ex-factory. The “2700W” resistor I selected measured 2762W. Use that resistor as “R” in the circuit below. The “unknown” capacitor C is the 10nF value to be accurately measured. Set the function generator initially to 10kHz. Measure the frequency with a frequency counter if the function generator’s display is not sufficiently accurate. You should be able to set the function generator frequency with an accuracy better than ±50Hz (±0.5% <at> 10kHz). Most function generators will display the frequency much more accurately than this without the need to use a frequency counter. Connect your oscilloscope to measure Vin and Vout. Many modern oscilloscopes have a digital measurement function that will report these values to three-digit accuracy. Adjust the frequency of the function generator so that the output voltage (Vout) is exactly half that of Vin as measured on the oscilloscope. Some adjustment of the generator’s output level may be required to measure both voltages accurately to achieve the best result. Measuring this 2:1 ratio accurately is the source of the greatest measurement error in this process, so care is required. I found the generator had to be set to 9611Hz, so C = √3 ÷ 2πfR = √3 ÷ (2π × 9611Hz × 2762W) = 10.385nF. The scope probe’s tip capacitance is in parallel with the Vout measurement. This capacitance is typically stated on the probe; mine was specified as 15pF. Deducting this from the calculated capacitance gives 10.37nF. This is the exact value of the How to accurately measure a capacitor’s capacitor. With the test equipment value using a function generator, and procedure described, the result frequency meter and multimeter (for can be shown to be accurate to measuring the R value). ±1.5%. in the main resonant circuit. Some require another for calibration. These parts can be difficult to find, and they can be expensive to buy. One solution used in the past by the home builder was to measure several ±5% or ±10% tolerance capacitors, selecting one that is as close as possible to the desired value. This worked at a time when many parts were not sorted by tolerance bands, so selecting one from many parts yielded a value close to the desired value. Australia's electronics magazine This approach also required a very accurate capacitance meter. The lack of such a meter is often the reason for building an LC meter in the first place! While a few constructors may have access to a suitable meter through work or a friend, this problem can be a significant barrier for potential builders. One solution to this ‘chicken and egg’ capacitor problem was described by retired Hewlett Packard engineer Jim McLucas in an article entitled “Circuit measures capacitance or May 2026  65 Photo 1: the prototype PCB without the OLED fitted. The socket for IC2 differs slightly from the approach described in the text. The USB-C connector is mounted at upper-right. Photo 2: a side-view of the prototype shows how the OLED sits just above or on the ATtiny85. This construction method reduces the overall height of the meter. Photo 3: the PCB sits in the lower half of the 3D-printed case. The pressed-in nuts can be seen at upper left and lower right. Photo 4: the Simple LC Meter measuring a 47μH test inductor. Photo 5: this simple jig makes it easier to measure the value of small SMD components. Fig.4: only a few parts are mounted on the board; this PCB overlay shows clearly their locations and the orientations of IC1 and IC2. 66 Silicon Chip Australia's electronics magazine inductance” from Electronic Design magazine, October 21, 2010 (see the panel on “Measuring capacitance accurately” above). Careful measurements using several methods and meters showed this technique was as accurate as claimed. The procedure is also relatively easy, especially when measuring a single capacitor value such as 1nF (1000pF). In this LC meter, the capacitor in question needs only to be approximately 1000pF. Using one of these methods, it is possible to accurately establish the value of the chosen reference capacitor. Write the value down, because this value will be programmed into the ATtiny85 later. It actually doesn’t matter if your capacitor is actually 5% or more away from the preferred or ideal value. For example, one version of this meter used an 820pF polystyrene capacitor to accurately measure inductors and capacitors for years! In short, in this design, provided the value of your chosen capacitor is accurately measured and saved in the LC meter’s EEPROM memory, the LC meter software takes care of the rest. Construction The LC Meter is built on a double-­ sided PCB coded 04103261 that measures 67 × 20mm. Start by fitting the resistors and capacitors, then the 74HC04 IC, using the overlay diagram (Fig.4) as a guide. Proceed to fit the USB-C connector and the 8MHz crystal. You’re almost 50% of the way through construction already (by parts count, anyway)! Next, mount the IC socket for the ATtiny85 to the PCB. It is drilled to allow the socket to fit down into the PCB to reduce the overall height of the assembly. The excess pin length can be trimmed from the IC socket after it is soldered into place. Fit the four-way female pin strip for the OLED display on the PCB. OLED screens often come with standard square pin headers (sometimes soldered, sometimes separate) but the LC meter’s size can again be usefully reduced if machined IC socket pin strips are used. So, if your screen has a header soldered to it, remove it and re-fit the round-pin machined header. Photos 1 & 2 show the general arrangement. The OLED display should be fitted with a matching connector, in this case siliconchip.com.au a four-way machined IC male-male pin strip. As Photo 2 shows, when the display is attached to the PCB, it will rest on or very slightly above the top surface of the ATtiny85 (IC2). Solder the DPDT slide and pushbutton switches in place, then proceed to mount the reference capacitor, followed by the inductor. Space both about 1mm above the PCB to allow them to be more easily bent over at a slight angle. This is to allow the PCB to be mounted in the compact 3D-printed enclosure. Do not fit the crocodile clips yet. This will be done as part of the 3D-printed enclosure assembly. Before final assembly, you’ll need to program the ATtiny85 unless you purchased a pre-programmed chip. The instructions for this are in the text box “Programming the ATtiny85”. Once programmed, carefully fit the ATtiny85 into the IC socket, making sure the chip is correctly orientated. Pin 1 of the ATtiny85 is usually marked with a tiny circle. The orientation can also be checked against the component overlay on the PCB (Fig.4). Now plug the OLED screen into place. Final assembly the soldering iron doesn’t go anywhere near the 3D-printed parts! Slide the LC meter PCB into the base and arrange it so it is flat and the USB socket aligns with the matching hole in the base. Check that your USB-C cable can connect with the PCB-mounted connector. Leave it in place briefly while adding a couple of drops of hot glue to the edges of the PCB to keep it firmly in place, if necessary. Finally, secure the cover in place with the two M2 machine screws. Inductor & capacitor testing A wide variety of methods have been tried for connecting the components being tested. The LC test inputs on the PCB allow for various builder preferences. The approach shown here uses a pair of small alligator (crocodile?) clips on short lengths of stranded hookup wire. I find this the easiest, most practical and robust approach. SMD parts may prove troublesome to clip onto, though. For the occasional test, the clips are fine, if a little clumsy at times. One alternative for testing SMD parts I tested is shown in Photo 5. I cut a very thin slot into the copper side of a scrap of single-sided PCB substrate. A further blank PCB scrap was milled to match the dimensions of the most commonly used SMD parts: M2012/0805 (2.0 × 1.2mm), M3216/1206 (3.2 × 1.6mm) etc. This was glued on top of the first PCB so Parts List – Simple LC Meter 1 double-sided PCB coded 04103261, 67 × 20mm 1 3D-printed enclosure [STL files: Silicon Chip SC3581] 1 3D-printed pushbutton extender [STL file: SC3581] 1 74HC04 SMD hex inverter IC, SOIC-14 (IC1) 1 ATtiny85-20PU microcontroller programmed with 0410326A.HEX/EEP (IC2) [Altronics Z5105 or Jaycar ZZ8721 (both unprogrammed)] 1 128×32-pixel 0.91-inch I2C OLED display module [AliExpress 1005003743893780, Silicon Chip SC7484] 1 pair of small red & black crocodile/alligator clips (CON1a/CON1b) [Jaycar HM3020] 1 female machined 4-pin strip (CON2) [cut from Altronics P5400A or Jaycar PI6470] 1 4-pin machined male-to-male header strip (for the OLED) [AliExpress 1005007564228387] 1 USB-C Type C-05 PCB-mount 2-pin socket (CON3) [AliExpress 1005005371954812] 1 100μH axial RF choke (L1) [Jaycar LF1534] 1 SS22H02-G5 5mm miniature PCB-mounting vertical DPDT slide switch (S1) [AliExpress 1005009907089109] 1 4-pin PCB-mounting tactile pushbutton switch with 6mm-long actuator (S2) [Altronics S1124, Jaycar SP0603] 1 8MHz crystal, HC-49U (X1) [Altronics V1249A or Jaycar RQ5287] 1 8-pin DIL machine pin IC socket (for IC2) 2 M2 × 5mm countersunk head machine screws and hex nuts 2 short (~100mm) lengths of medium-duty hookup wire Capacitors (all SMD M2012/0805-size 50V X7R unless noted) 1 1μF 1 100nF 1 1nF 50V polystyrene [AliExpress 1005006112435371] 2 4.7pF NP0/C0G Resistors (all SMD 0805-size ±1%) 1 1MW 1 22kW 1 100kW 1 5.6kW These next steps assume the use of the 3D-printed enclosure designed for this meter, although the PCB can be mounted into almost any suitable enclosure. The 3D-printed case usefully avoids the need for precision drilling and cutting of the various holes required. There is also a little pushbutton shaft extender, also 3D-printed. This is suitable for 6-10mm shaft length miniature pushbuttons. This is placed over the top of the pushbutton shaft just prior to screwing on the top cover. Begin final assembly by inserting the two M2 nuts into the base using a soldering iron. Locate them in place and press them into the base with a light and very brief press of the soldering iron tip. They should lie just at or slightly below the mating surface of the base and cover. Attach the red and black miniature crocodile clips to two 55mm lengths of stranded hookup wire. Strip 4mm of insulation from the free ends and tin the stranded wire with solder. Pass these ends through the hole located on the left-hand side of the lower half of the enclosure and carefully solder them to the LC test pin inputs. Ensure Figs.5-7: the enclosure and pushbutton cap may all be 3D-printed with PLA filament. The prototype was printed with grey PLA for the case, while the pushbutton cap was printed in a contrasting blue. siliconchip.com.au Australia's electronics magazine May 2026  67 Programming the ATtiny85 Download the HEX and EEP files for the LC meter from siliconchip.au/Shop/6/3580 The EEP (EEPROM) file provided contains a nominal value of 1000pF for the reference capacitor. If you have an in-circuit programmer like the USBasp, you will also need a way to connect the correct lines to the pins on the chip. This is most easily done using an adaptor board. It saves adding a 6-pin programming socket to each PCB. My 8-pin adaptor was published in the September 2020 issue (page 47; siliconchip. au/Article/14563) and the PCB is still available (siliconchip.au/Shop/8/5642) Once you have the chip plugged into an adaptor, connect the programmer to your computer. Download and open a programming application (such as Extreme Burner) and load the HEX and EEP files into this program. It is almost certain you will need to modify the contents of the EEP file with the precise value of your reference capacitor. The value is saved in picofarads, eg, 1.015nF is saved as 1015 (pF). EEPROM values are usually edited as two-digit hexadecimal bytes (in this case, two bytes, making up a four-digit hex value). You can use the following website to convert the value to hex: www.rapidtables.com/convert/number/decimal-to-hex.html One of my LC meters used a 995pF capacitor; 995 is 03E3 in hexadecimal. This value was entered into cells 02 and 03 in the first line of the EEPROM tab in Extreme Burner (see Screen 1). Just click your mouse on the cell to be changed and enter the new value. Note that the least significant byte (E3 in this case) comes first, in cell 02, and the most significant byte (03) goes in cell 03. Now program your ATtiny85 with the HEX file, then the EEP file. Click on the “Write” tab in Extreme and select the file you are sending to the ATtiny85. Next, program the hardware configuration fuses in the ATtiny85. Table 1 shows the required fuse settings. You need to set these after loading the HEX and EEP files before the LC Meter will work. To set the fuses, click on the Fuse Bits/Setting tab (Screen 2), enter the values shown, and click on the Write selection boxes for the Low and High fuses (the others may safely be ignored). When you have done this, write the fuse settings to the ATtiny85 by clicking on the Write button at the lower right of this tab. That’s it! If you need more information about the programming procedure, there are some helpful tutorials on this topic that can be found on the Adafruit and Instructables websites. Table 1 – ATtiny85 fuse settings Fuse Hex value Comment Lock byte FF Flash not locked Extended byte FF Self-programming disabled High Byte 5F Defaults except RSTDISBL=0 Low byte E0 Defaults except CKDIV8=0 & CKSEL1=0 Silicon Chip Operation A simple sign-on message is displayed when the meter is powered up. Once the measurement mode (inductance or capacitance) has been selected with the LC switch, the meter must then be calibrated. Press CAL and wait a moment. You will see a display prompting you to short the test leads together (for inductance measurements) or leave them open (for capacitance measurements). Once calibrated, the component can be connected, and the meter will then display its value. The meter also reports the oscillator frequency during the measurement. This allows invalid results to be easily detected; for example, if a faulty component is tested or one with a value outside the range of the meter. The prototype will measure values from less than 10nH to about 100mH and from less than 10pF to about 1μF. If the reference capacitor has been carefully measured, the results can be expected to be within ±2%. Final remarks Screen 2: another tab in Extreme allows the fuse bits to be set and then written. Do this after you have written the HEX and the EEP files to the ATtiny85. This meter, in one form or another and with minor variations in the software, has been in continuous use on my bench for well over a decade. The latest version described here has been in use for over 18 months. It is, by far, the most compact and convenient to use. The only problem has been that it is also small enough to become buried under other stuff on my workbench! It is quick, simple & inexpensive to build, and so convenient to use that I find myself taking its convenience and accuracy for granted. I have long since forgotten just how time-­consuming the alternative methods were prior to the arrival of such LC meters. Even if you already have an LC meter, I encourage you to take the time to build this one. Once built, you’ll find yourself reaching for it all SC the time, too. Australia's electronics magazine siliconchip.com.au Screen 1: the value of the reference capacitor entered into the EEPROM tab in the application. 68 that the slot sat midway in this gap (see Photo 5). The SMD part can easily be placed into this assembly for testing and measurement. The arrangement can then be connected to the LC meter using the alligator clips. Another version used miniature pin connectors, which allowed the assembly to be plugged into a different version of the LC meter when required. O ver 20 years ago, my mother was becoming infirm and had a tendency to fall and couldn’t get up. I lived too far away to visit every day, but near enough that I could attend in an emergency. What was needed was a way to alert me to any potential problem. These were the days before the internet was common in the home, so I devised a plan to connect the PIR (passive infra-red) movement sensors in the burglar alarm to a cheap landline telephone handset from the local discount store. All that was needed was an interface between the alarm panel and the ‘phone. The system potentially saved my mother’s life on three occasions, when she had fallen and couldn’t get up. On a fourth occasion, she had been taken into hospital but had not bothered to tell family, friends or the local community services, causing a major panic. I got the alert just as I landed in Amsterdam for a well-earned weekend break. However, at least I was able to inform family members of a potential problem. The original solution The original circuit is shown overleaf for interest (Fig.1). The burglar alarm’s communicator outputs and three PIR sensors on separate zones were connected to a PIC16F84 microprocessor (IC1) via NPN transistors Q1-Q5. This allowed the PIC processor to detect activity in the three PIR zones, monitor for alarm conditions and also determine whether the burglar alarm was set (armed) on unset (clear). I removed the keypad, microphone and ‘off hook’ switches from the ‘phone. The keypad was replaced Image source: https://unsplash.com/photos/a-black-and-white-alarm-clock-on-a-white-background-CfuOZPNSr6E WiFi Alarm Monitor If someone lives by themselves, especially if they are elderly, they can end up in situations where they need help but can’t get it. This alarm system provides a way to alert others when there is a problem. A project to help the elderly by Kenneth Horton by two quad opto-isolators (IC3 & IC4) driven by a 74LS139 dual 1-of-4 decoder, IC6. The ‘off hook’ switch was replaced by relay RLY1; both were activated by the PIC16F84. I replaced the microphone with a 1:1 ratio isolating transformer. The first version sent an alert in Morse code, but this was later replaced by an ISD1110 voice encoder chip (IC5) to give spoken alerts. If the burglar alarm was activated, or no movement was detected for a set period, the PIC processor would dial my mobile number and the voice chip would inform me that there was a problem. Monitoring whether the panel was set (armed) or unset (clear) allowed different time intervals to be set. The top and bottom of the PCB used to prototype the WiFi Alarm Monitor. It’s very simple compared to the older landline-based circuit shown in Fig.1 siliconchip.com.au Australia's electronics magazine My mother set the panel at night upon going to bed, and in this case, there was a much longer time delay without movement before an alert was generated than during the daytime when the panel was unset. Bringing it up to date I am not yet at the stage where I am infirm, but I know that the time may come when my family are as concerned about me as I was about my mother. I decided that I should update the design, making use of the now widely available internet and WiFi, and install it while I have my faculties. The system performs two functions: first, it will alert me or my family in case of an alarm condition, such as the burglar alarm being set off. Second, it will monitor my daily activity. If none is detected, it will alert the family of a potential problem. In my case, the alarm system consists of both door switches and PIR detectors, but the solution can be tailored to individual requirements. Monitoring alarm conditions is straightforward. However, monitoring daily activity is more in-depth. There are three different modes: • Daytime, when the occupant is at home and the alarm panel is unset. • Nighttime, when the occupant is in bed and the panel is set (armed). • When the occupant has left the premises and presumably armed the alarm. May 2026  69 Fig.1: the circuit of my original alarm dialler, which interfaced with the (now largely obsolete) public telephone network by connecting to an old handset via CON2, CON3 & CON4. That allowed it to dial me after a delay if it sensed a lack of activity. The WiFi Alarm monitor uses a single Raspberry Pi Pico W (shown enlarged). Fig.2: the new Alarm Monitor is simpler and more modern, using a Raspberry Pi Pico W to send emails and/or SMSs if the activity coming from the alarm via level-shifters IC2 and IC3 looks suspiciously quiet. ▶ During the daytime, the system needs to check on activity by monitoring door switches and PIRs. At night, when the panel is set, the system needs to check that the panel is unset the following morning. If the occupant has gone out, the activity monitor needs to be disabled because the user may simply have popped to the shops, or they may have gone on a three-month world cruise! In this case, inactivity alerts would be annoying, to say the least! The use of the exit door within minutes of the panel being set (armed) differentiates between the panel being set 70 Silicon Chip Australia's electronics magazine siliconchip.com.au give a degree of separation between the alarm panel and the interface. These 12 inputs, together with an optional test button (S1) are connected to a Raspberry Pi Pico W, which provides all the intelligence and a connection to the internet. The Raspberry Pi Pico W is the version with built-in WiFi. The only other components are a simple linear power supply with an axial fuse to convert the 12V from the panel to five volts for the Raspberry Pi Pico W. This is fed to the Raspberry Pi via a schottky diode so that it can safely work in parallel with a USB supply. Software description while the user is in the premises and when he or she has gone out. The system can send emails to four different groups of people, depending on what has triggered the alert, and can also send SMSs to up to four different telephone numbers. To send SMS text messages, you will need a free Twilio account. Setting one up is easy; visit www. twilio.com for more details. Twilio works in the UK, Australia, NZ, EU, USA and many other countries too. Circuit description As with many modern circuits, the siliconchip.com.au hardware is relatively simple, and all the intelligence is within the software. The updated circuit is shown in Fig.2. Up to 12 inputs from the alarm panel, both individual zones and communicator outputs, can be monitored via CON1 & CON2. Communicator outputs are typically: panel armed, alarm condition, fire, panic and abort, together with a 12V supply. The 12 inputs are connected via 10kW resistors to two 74HC4050 high-voltage input non-inverting buffers, which allow the (typically) up to 12V signals from the alarm panel to be safely converted to 3.3V. The resistors Australia's electronics magazine The software for the Raspberry Pi Pico W is written in MicroPython. There are three files: main.py, umail. py and parameters.py. The first two files should be installed as supplied. The parameters.py file needs to be edited to tailor the system to your individual requirements. The parameters.py file contains numerous constants and arrays. The program has been designed to be as flexible as possible, to allow for many different scenarios. The file parameters.py can be edited in a text editor, or with Thonny, as described later. Note that MicroPython’s code is strictly case sensitive, so great care is needed while editing to avoid unintentional errors! The first section of parameters.py contains constants that should not be altered. The user-defined parameters are from around line number 47 through to the end of the file. Looking at each section in turn: The first section of comments on lines 47 to 77 is not essential, but I found it useful in clarifying my requirements. I suggest that you review and change these comments to define your own requirements. Don’t forget to include a hash mark (#) at the start of each comment line. Editor's note: the line numbers do not match up to the Listings shown in this article (taken from “parameters. py”, as we have removed the comments and line breaks due to space restrictions. The downloaded file match the referenced lines. The next section (lines 78-101, Listing 1) sets timings for various functions in seconds, minutes or hours as appropriate. May 2026  71 83. 84. 85. 86. 87. 88. 89. 90. 91. 92. 93. Watchdog = const(True) Set_timeout = const(11 * Hours) Primary_timeout = const(8 * Hours) Secondary_timeout = const(5 * Hours) Exit_timeout = const(3 * Minutes) First_delay = const(30 * Seconds) Second_delay = const(5 * Minutes) WiFi_timeout = const(15) WiFi_retry = const(10 * Minutes) Maximum_retries = const(3) Periodic_checking = const(7 * Days) Listing 1: this section of the code defines various delays and settings. We have removed comments and new lines for brevity. The line numbering isn’t an exact match to the actual file, it’s just there to make it easier to follow. 107. 108. 109. 110. 111. 112. 113. 114. 115. 116. 117. 118. 119. 120. 121. 122. 123. 124. 125. WiFi_username = "Your SSID" WiFi_password = "Your password" smtp_address = "smtp.aaa.com" smtp_port = 25 smtp_username = "Your login" smtp_password = "Your password" Email_from = "from<at>aaa.com" Email_subject = "Alarm status report" Email_to_1 = "Contact1<at>aaa.com" Email_to_2 = "Contact2<at>aaa.com" Email_to_3 = "Contact3<at>aaa.com" Email_to_4 = "Contact4<at>aaa.com" Twilio_Account = "Twilio account number" Twilio_Auth = "Twilio authorisation" Twilio_phone_no = "Twilio phone no" SMS_to_1 = "00000000001" SMS_to_2 = "00000000002" SMS_to_3 = "00000000003" SMS_to_4 = "00000000004" Listing 2: the WiFi, email, and SMS settings. 136. Zone_name = { 137. 0: ["Front door", Primary_zone | Exit_zone], 138. 1: ["Lounge PIR", Secondary_zone], 139. 2: ["Dining door", Primary_zone], 140. 3: ["Back door", Primary_zone], 141. 4: ["Hall PIR", Secondary_zone], 142. 5: ["Kitchen PIR", Secondary_zone], 143. 6: ["Abort", Abort_status], 144. 7: ["Panic", Communicator], 145. 8: ["Spare", Spare_zone], 146. 9: ["Spare", Spare_zone], 147. 10:["Panel", Panel_status], 148. 11:["Alarm", Alarm_status], 149. 12:["Test", Test_button] 150. } Listing 3: the zone definitions. Watchdog should be set to “True”. Only set it to “False” while testing. Set_timeout is the amount of time before an alert is sent when the panel is set. Normally, this will be at nighttime when the alarm panel is set and the user is in bed. As noted previously, this timeout is disabled if the exit zone has been triggered, indicating that the user has left the premises. The values Primary_timeout and Secondary_timeout similarly set the amount of time before an alert when the panel is unset; usually, this will be during the day, when the user is its home. Primary zones are where there is a definite action by the person being monitored, such as opening or closing a door that has a door switch. Secondary zones are typically PIR movement sensors, and these may be triggered accidentally by a person who has fallen trying to get up unsuccessfully, or a pet wandering through. As such, they are less reliable as an indication of activity compared with the primary zone. When relying on PIRs, you need to monitor more than one zone! Exit_timeout defines the amount of time between the panel being set (armed) and the exit door being triggered; it will usually be two or three minutes. It must be set for a longer time than that set in the alarm panel itself. Otherwise, the exit condition will not be recognised. First_delay is the amount of time between an alarm condition and the first alert being sent, and is typically set to one or two minutes so that false alarms can be cancelled. Second_delay is the amount of time between the alert being sent to the first contact and the subsequent contacts. WiFi_timeout is the length of time the system tries to connect to the router before timing out. 180. Alarm_types = { 181. "Alarm": ["Alarm", Delay1 | Email_Contact1 | Delay2 | SMS_Contact2], 182. "Communicator": ["Communicator", Email_Contact1], 183. "No_Activity_Clear": ["No activity panel NOT set", Email_Contact1 | Delay2 | Email_Contact2 | SMS_Contact3], 184. "No_Activity_Set": ["No activity panel set", Email_Contact1 | Delay2 | Email_Contact2 | SMS_Contact3], 185. "Test": ["Test message", Terminal | Email_Contact1], 186. "Check_in": ["Periodic check-in", Email_Contact1], 187. "Restart": ["Alarm monitor restart", Email_Contact1] 188. } Listing 4: the actions to be performed for each alert condition. 72 Silicon Chip Australia's electronics magazine siliconchip.com.au WiFi_retry is the amount of time between attempts to connect to the WiFi network, assuming that it has been unsuccessful. Maximum_retries sets the maximum number of attempts to connect to WiFi or send an SMS text message. This is to prevent the monitor from entering an endless loop due to a WiFi or SMS problem, and allows it to move on to subsequent actions. Periodic_checking enables the monitor to send a periodic email or text message to confirm that it is up and running. A value of 0 disables it. The next section (lines 103 to 125, Listing 2) sets your WiFi username and password, and your email login details, followed by the email addresses and SMS phone numbers of your contacts. I have found different email providers to be a little fickle about the format of parameters, so some tailoring may be required. You should be able to set more than one email address, possibly separated by a semicolon (;). Caution and careful testing are needed when setting the email login parameters. Incorrect values can cause the program to crash and thus not send the alert messages. As previously mentioned, you will need a free Twilio account to send SMS text messages. The following section (lines 127 to 150, Listing 3) defines the function of each of the 13 input channels to the system. For each input channel, there are two parameters: a text description, followed by its functions. More than one function can be defined with the ‘inclusive or’ symbol (|), so “Primary_ zone | Exit_zone” defines the input as both a primary zone and an exit zone. • Panel_status defines whether the alarm panel is set (armed) or unset (clear). • Alarm_status is set when the burglar alarm is activated (an alarm condition) by an intruder. 201. Activity_conditions = [ 202. [2,0], 203. [1,2], 204. [0,3], 205. [-1,-1] 206. ] Listing 5: this section of the code sets the number of primary/secondary zones that need to be triggered to indicate activity. siliconchip.com.au Parts List – WiFi Alarm Monitor 1 single-sided PCB coded 01304261, 57 × 57mm 1 suitable plastic enclosure (eg, 3D printed) 1 Raspberry Pi Pico W microcontroller module (MOD1) 2 20-pin headers, 2.54mm pitch (for MOD1) 2 20-pin female header sockets, 2.54mm pitch (for MOD1) 1 250mA miniature axial fuse (F1) 2 74HC4050 level-shifter ICs, SOIC-16 (IC2, IC3) 1 AMS1117-5 5V LDO linear voltage regulator, SOT-223 (REG4) 1 1N5819 40V 1A axial schottky diode (D1) 12 10kW ±5% or better axial resistors (4.7kW to 22kW resistors would likely work too) 2 100nF 50V X7R SMD ceramic capacitors, M2012/0805 or M3216/1206 size 1 10μF 50V X7R SMD ceramic capacitor, M3216/1206 or M3226/1210 size 4 3-way miniature (0.15in/3.81mm) screw terminal blocks (CON1, CON2) OR 3 4-way miniature (0.15in/3.81mm) screw terminal blocks (CON1, CON2) 1 2-way polarised header and matching plug, 2.54mm pitch (CON3; optional; for S1) 1 2-way miniature (0.15in/3.81mm) screw terminal block (CON4) 1 momentary pushbutton switch (S1; optional) • Communicator is typically the ‘panic’ or ‘fire’ communicator outputs, if required. • Abort_status indicates that an alarm condition has been cancelled. • Spare_zone defines any unused inputs; these should also be connected to ground electrically. • Test_button monitors the 13th input (S1) and will send a test message. The next section (lines 152 to 188, Listing 4) defines which actions are to be performed for each of the alert conditions: • alarm • communicator output • no activity while the panel is not set (clear) • no activity while the panel is set (armed) • test message • periodic ‘health’ check-in • start-up/reset These are fixed conditions in the software and should not be altered. For each of the alert conditions, there is a text description followed by a list of actions. These consist of delays, emails and SMS messages to various contacts. • Delay1 is typically a short delay to allow time for a false alarm to be cancelled. • Email_contactx sends an email to that contact or group of contacts. • SMS_contactx sends an SMS message to a single contact. • Delay2 sets a delay between contacting contact 1 and the other contacts. Australia's electronics magazine • Terminal is for testing only and sends output via the USB interface. All the actions occur in a fixed sequence, defined in the subroutine Poll_alerts() in main.py. The sequence is: Delay1, Terminal, Email_contact1, SMS_contact1, Delay2, Email_contact2, SMS_contact2, Email_contact3, SMS_contact3, Email_contact4, SMS_ contact4. If no action is required for a certain condition, it can be set to 0. For example: “Restart”: [“Alarm monitor restart”, 0] If a WiFi connection cannot be made, the interface keeps trying at WiFi_retry intervals until Maximum_ retries has occurred and will not move on to the next action until a successful connection is made or the retry limit is exceeded. Maximum_retries also applies to attempts to send emails. No check is made that emails or SMS messages have been completed successfully; the interface will simply move on to the next action. If an email or SMS is unsuccessful, it is likely to be a hard fault due to a parameter error, and the interface would be tied up indefinitely! The final section (lines 190 to 206, Listing 5) sets the number of primary and or secondary zones that need to be triggered to indicate activity. As previously mentioned, primary zones give a clear indication of activity, while secondary zones may be triggered by a person in distress or a pet. May 2026  73 So, for accurate monitoring, a minimum of two secondary zones are needed unless a primary zone has been triggered. As a result, various combinations of primary and secondary zones can be set, for example [two primary zones] or [one primary zone and two secondary zones] or [three secondary zones]. Obviously, you cannot define more primary or secondary zones than those that are being monitored. Each line has the number of primary zones followed by the number of secondary zones. Each additional line provides an ‘inclusive or’ function, so 2,0 followed by 1,2 means [two primary zones and no secondary zones] or [one primary zone and two secondary zones]. Software libraries My software makes use of a thirdparty library, uMail (MicroMail) for MicroPython (https://github.com/ shawwwn/uMail). Also, for the SMS interface, I used code from Mahmood Mustafa Shilleh at siliconchip.au/ link/acat Construction The prototype was built on a single-­ sided printed circuit board with a RPi mounted on headers and sockets so it can be easily removed (and because there’s a diode mounted underneath it). The 74HC4050 ICs, linear voltage regulator and associated capacitors are all surface-mount devices. Axial resistors were used on the inputs of the 74HC4050s, as the layout of the gates on these chips is not particularly user-friendly and resistors are a convenient way of bridging to the input connectors. The prototype used Molex KK-style connectors for compatibility with previous wiring, but the PCB has been re-designed to use miniature screw terminal blocks with 0.15-inch (3.81mm) pin spacing (not the more typical 0.2-inch/5.08mm spacing). Looking at Fig.3, I recommend fitting the surface-­ mount components first, followed by the resistors and then the other components. If you only require a maximum of six inputs, the second 74HC4050 can be omitted; the weak internal pullups on the Raspberry Pi Pico module will automatically disable the remaining inputs. The finished board can be mounted in any convenient plastic project box, or if there is room, within the alarm panel itself. The author made a custom 3D-printed enclosure, but that is not necessary. If you do want to print that, the STL files are included in the software package at siliconchip.au/ Shop/6/3613 Software installation The software is installed on the Raspberry Pi using the free Thonny integrated development environment (IDE). The first step is to install the IDE from https://thonny.org Installation is quite straightforward and you will find a lot of useful information on the Thonny website and also at https://github.com/thonny/ thonny/wiki Once Thonny is installed, connect the Raspberry Pi to your computer using a USB lead while holding down the white button (BOOTSEL) on the Raspberry Pi, then start Thonny. You should see a window similar to that in Screen 1. Click on the bottom right corner where it says <no backend> and then select Install MicroPython (Screen 2). You should then see Screen 3. Target volume sets the location of the Raspberry Pi and should be filled in automatically. If it is blank, you need to disconnect the Raspberry Pi and connect it again while pressing the white button. Set: • MicroPython family to ‘RP2’ • Variant to ‘Raspberry Pi • Pico W / Pico WH’ • Version should be set automatically to the latest. Check that the parameters are correct and then click Install. When the installation is complete (which should only take a few seconds), click on the stop button (white square inside the red circle) and you should see Screen 4. If it does not appear, close Thonny, disconnect and reconnect the USB without pressing the white button, and then restart Thonny. The next step is to copy the source files onto the Raspberry Pi. As previously mentioned, MicroPython is strictly case sensitive, and this applies to file names as well as the source program. In the next step, the source files from your computer will be copied onto the Raspberry Pi. Editing files either on your computer or on the Raspberry Pi, does not update the other copy. You need to explicitly make a copy. Note that it may not be obvious whether files you are editing in the Thonny editing window are located on the computer or Raspberry Pi. The files main.py, parameters.py Fig.3: the board can be easily etched as it is single-sided, with all the through-hole parts on the top and a few SMDs on the underside. Take care with the polarity of the SMD ICs (their pin 1 indicators go towards the Pico) and note how D1 is mounted underneath the Pico W module. Because of that, and to make maintenance easier, it’s best to socket the Pico W. 74 Silicon Chip Australia's electronics magazine siliconchip.com.au Screen 1: the initial state of Thonny (a Python IDE) when you run it after installation. and umail.py need to be copied from your computer onto the Raspberry Pi. This is the time to edit the parameters. py file if you haven’t already done it (use your favourite text editor). Don’t forget to save a copy both to your computer and to the Raspberry Pi. In Thonny, click File → Open... and then select “This computer”. Open umail.py from your computer, then click File → Save copy... and this time select “Raspberry Pi Pico”. Type the filename “umail.py” and click OK. Repeat the above for the files main. py and parameters.py after making your edits. Now close Thonny, disconnect and reconnect the USB lead. The green light on the Raspberry Pi should flash at one-second intervals. Connecting the interface to the alarm panel Different alarm panels will vary slightly, but all should have multiple zones and a set of communicator outputs. The communicator outputs are fairly standard, as they are designed to interface with a range of devices. Each zone usually has two connections, ignoring tamper circuits. One connection will be at a fixed voltage (or ground), while the other is used to detect the input from the switch or sensor. It is necessary to connect the interface to this active signal. A quick test with a multimeter should identify the correct input to use. Failing that, try one and, if it does not work, try the other. On my Honeywell alarm panel, the active inputs are on the left. Don’t forget to ground any unused inputs. If they are left floating, they can overwhelm the Raspberry Pi with unwanted interrupts. If you want to send SMS messages, don’t forget to get a free Twilio account! The author’s monitor has been running without failure for over 18 months, so the Raspberry Pi and MicroPython software appear to be extremely stable. If possible, once the unit is installed, there should be easy access to the USB connector so that parameter updates can be easily installed. The Raspberry Pi will need to connect to a reliable WiFi network, so this needs to be taken into account. In particular, metal enclosures are unlikely SC to be suitable. siliconchip.com.au Screen 2: this menu lets you install MicroPython on the Pico W. Screen 3: set the options in this dialog as per the instructions in the text to install MicroPython. Screen 4: the Thonny IDE with MicroPython on the Pico W up and running. Australia's electronics magazine May 2026  75 By Andrew Levido Power Electronics Part 7: Resonant Converters & Soft Switching Higher switching frequencies can make input and output filters simpler, with smaller magnetics. They also allow a faster response to changes in the load current. Switching losses become a major problem at higher frequencies, but there is a solution. W e saw last month that switching losses in power electronic converters can become dominant as switching frequencies increase. However, higher frequencies are desirable as they allow the designer to increase the bandwidth of the control system, so it can respond to load changes more quickly. We will start with a quick review of how a Mosfet switches on and off. The upper-left part of Fig.1 shows a typical boost converter. We will assume this is operating in periodic steadystate and that the inductor current is more-or-less constant at the timescale of the switch-on and switch-off of the Mosfet, typically in the 10ns range. We will also assume that the Mosfet is off and the full load current is flowing through the diode at the instant of switch-off. I have also drawn the gate equivalent circuit of the Mosfet below the boost converter circuit. When the device is off, the gate voltage is zero, the gatesource capacitance (Cgs) is fully discharged and the gate-drain capacitance (Cgd) is charged to the drain voltage, vd. The gate-drain capacitance is much smaller than the gate-source capacitance, but it plays a big part in switching losses, as we shall see. The resistance Rg is the combination Fig.1: in inductive circuits such as this, a Mosfet’s drain voltage cannot begin to change until the current fully commutates to or from it. This results in significant switch-on and switch-off losses. The diode reverse recovery current makes this worse. 76 Silicon Chip Australia's electronics magazine of the internal gate resistance and the source impedance of the Mosfet driver. The voltage vg(int) represents the voltage at the gate metallisation on the Mosfet die that modulates the conductivity of the channel. The plot labelled “Mosfet switch-on” shows what happens when we switch the Mosfet on. When the gate voltage is applied at time t0, nothing happens immediately because the internal gate voltage (black trace) has yet to charge to the switch-on threshold. Once the threshold voltage is reached at time t1, the drain current (red trace) begins to rise. Because the load is inductive, the drain current must rise to its full extent before the drain-source voltage can begin to fall, at time t2. You can understand why this is the case with reference to the boost converter schematic. When the Mosfet starts to conduct, the current shifts (commutates) from the diode to the Mosfet. Until the Mosfet takes over 100% of the inductor current, the balance continues to flow through the diode, keeping the Mosfet’s drain voltage fixed at the converter’s output voltage. This same phenomenon occurs in many converter types, including buck converters, but it’s easiest to visualise with the boost converter since the Mosfet is grounded. The rate at which the drain voltage can fall is determined by how fast Cgd can be discharged. The only thing discharging Cgd is the current i Cgd provided by the gate drive. While vds is falling, all the gate current is diverted into Cgd due to the Miller effect, so the internal gate voltage remains essentially constant until the drain-source voltage reaches (almost) zero at time t3. This ‘flat spot’ on the internal gate voltage is known as the Miller plateau. After t4, the two gate capacitances are effectively in parallel, and the siliconchip.com.au siliconchip.com.au 20V 18V 16V V(vg) 14V 12V 10V 8V 6V 4V 2V 0V 8kW V(vd)* - I(R1) 6kW 4kW 2kW -2kW 500V 30A 400V 24A 300V 18A 200V 12A 100V 6A 0V 380.96μs 380.97μs 380.98μs 380.99μs 381.00μs 381.01μs 381.02μs 381.03μs 381.04μs 381.05μs -I(R1) 0kW V(vd) gate voltage continues to rise to its final value at t4, where the channel is fully enhanced and the Mosfet’s on-­ resistance is minimised. Switch-off is basically the reverse of this process. The importance of all this is that there is a period, from t1 to t3, where there is significant voltage across and current flowing through the device at the same time, and therefore considerable power dissipated during the relatively short switch-on and switchoff periods. In fact, things are worse than I just described if we take into account the ‘switch-off’ characteristics of the diode. When a diode switches from the conduction state to the blocking state, it does not switch off instantaneously. A large reverse current flows for a short period while the diode recovers its blocking capability – shown in the “Diode switch-off” plot. This ‘reverse recovery’ current occurs because the majority carriers stored in the PN junction have to be extracted when the diode is reverse-­ biased. The amount of this charge (Qrr in the data sheets) is small, but because it moves very quickly, the peak current can be high. This does not have a huge impact on the diode losses, but can contribute significantly to Mosfet losses. When the Mosfet switches on at time t2 and the inductor current commutates from the diode, the Mosfet sees an additional current spike due to the diode’s reverse recovery (bottom chart). This occurs while the drainsource voltage is still high, so it adds to the Mosfet switch-on losses. While it is often convenient to think of power Mosfets as voltage-driven devices, the description above demonstrates the importance of gate current in the switching process. The rate of change of drain-source voltage (dv/dt) during switching depends on the gatedrain capacitance and the gate current that charges and discharges it. You generally need to drive the gate hard if you want to increase the dv/ dt and minimise switching loss. However, a higher dv/dt produces in significantly more conducted and radiated EMI, so finding a compromise is usually necessary. How significant are these switching losses? I made a simulation of the boost converter circuit using the SiHA120N60E Mosfet. This is a 650V, 25A-rated device in a TO-220 package. 0A 381.06μs Fig.2: this simulation of the circuit in Fig.1 uses the SiHA120N60E Mosfet switching 400V at 20A. The switch-on losses peak at 7.5kW, although only for a few nanoseconds. Fig.3: a resonant circuit like this can be described by two quantities: the natural frequency and the damping factor. We often use the ‘quality factor’ or Q to describe the relationship between the two. I set the boost converter input voltage to 200V, the output voltage to 400V and the load current to a slightly unrealistic 20A. I drove the gate to 15V via a 10W gate resistor. The simulated switching waveforms are shown in Fig.2. You can clearly see that the drain current (red) rises fully before the drain-source voltage (blue) can begin to fall. You can also see the Miller plateau in the gate voltage (green). The purple trace is the instantaneous power dissipation in the Mosfet. It peaks at about 7.5kW, although the whole spike is only about eight nanoseconds long. The total energy dissipated at switch-on is about 30µJ. If we assume the same for switch off, the total will be 60µJ per cycle. At 10kHz, this corresponds to a modest 600mW in losses, Australia's electronics magazine but if we want to switch at 1MHz, we are looking at switching losses of 60W – a much less attractive proposition! Resonant circuits Since switching losses are the product of voltage across and current through the switch, one way to reduce or eliminate switching losses would be to ensure that one or both of these quantities is zero at the time of switching. This type of switching is sometimes called zero-voltage switching (ZVS), zero-current switching (ZCS) or just described by the generic term ‘soft switching’. The usual way to ensure that voltage or current is zero when we switch is to exploit resonance. For a quick refresher on resonance, take a look at Fig.3, which shows a simple RLC May 2026  77 filter with a DC source and a switch that closes at time zero. When the switch initially closes, a current will build up in the inductor, charging the capacitor through the resistor. The voltage on the capacitor will continue to rise past Vsrc to the point where the current in the inductor reverses and it begins to fall. When the capacitor voltage falls low enough that the inductor current reverses again, it starts to rise. This oscillation continues, but is damped by the resistance. Eventually, the capacitor voltage settles at Vsrc and the inductor current goes to zero. This is a damped oscillation. If the resistance were zero, the oscillations would continue indefinitely (in theory). If the resistor had a very high value, the circuit would behave like a standard RC filter, with the capacitor voltage rising smoothly (and exponentially) to Vsrc. We can therefore describe these resonant circuits with two quantities: the natural frequency and the damping factor. The natural frequency, designated ω0, is the frequency at which the undamped LC network would oscillate. This is given by ω0 = 1 ÷ √LC. The damping factor, designated by the Greek letter α, is equal to R ÷ 2L. The damped circuit will oscillate at a frequency lower than the natural frequency. This frequency, ωd, called the natural frequency, is equal to √ω02 – α2. These frequencies are expressed in radians per second, where 2π radians per second equals 1Hz. We don’t generally use the damping factor directly in our design process. Instead, we use a related quantity, the ‘quality factor’ or Q of the circuit. Q relates the damping factor to the natural frequency by the expression Q = ω0 ÷ 2α. A resonant circuit with high Q has low damping, and vice versa. Silicon Chip kcaBBack Issues $10.00 + post $11.50 + post $12.50 + post $13.00 + post $14.00 + post January 1997 to October 2021 November 2021 to September 2023 October 2023 to September 2024 October 2024 to August 2025 September 2025 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 Fig.4: if we switch this resonant DC-AC converter at its natural frequency, the inductive and capacitive reactances cancel, and maximum power is transferred to the resistive load. By shifting the frequency above or below the natural frequency, we can control the power to the load. of the square wave. This gain is called the ‘tank gain’. If the switching frequency is a little higher or lower than the natural frequency, the circuit looks a bit inductive or capacitive, respectively. The tank gain falls off either way, and the amount of power transferred to the load reduces. We can therefore control the load power by frequency-­ modulating the drive signal. We can choose to use either ‘above resonance’ or ‘below resonance’ control strategies. We will see how this works in practice later. The graph in Fig.4 suggests that switching occurs at the current zero-crossing, but this is a bit misleading. It is true that the current is near-zero at the time of switching if the switching frequency is precisely aligned with the resonant frequency, but we have already discussed that we will operate at a higher or lower frequency to control the output power. However, it is easy enough to modify this circuit to achieve zero-voltage switching. It just requires the addition of a small capacitor across each switch and a short ‘dead time’ during which both switches are off. This is shown in Fig.5. Here, we are using over-­resonance control, so the LC filter looks inductive and the current lags the voltage by the angle θ. The charts to the right of the figure show the load current (blue) and the voltage across the lower switch, S2 (red). During period A, the upper switch S1 is conducting, so C1 is discharged and C2 is charged to Vsrc. At the beginning of period B, S1 opens while the load current is still positive. Capacitors C1 and C2 take over providing the load current, and the voltage across S2 falls while C1 charges and C2 discharges. Australia's electronics magazine siliconchip.com.au 78 Silicon Chip You can play around with substituting these expressions into each other and get two other useful definitions: Q = ω0L ÷ R and Q = 1 ÷ ω0CR. We can use this information to build a resonant DC-AC converter, as shown in Fig.4. A DC source feeds a half-bridge switch followed by an LC series filter and a resistive load. The end of the load is held at ½Vsrc by the two bypass capacitors. These have a value large enough that their midpoint voltage remains more-or-less constant at the switching frequency. The voltage across the filter and load is therefore a square wave with amplitude ½Vsrc, as shown in the red trace. If we switch the converter at a frequency equal to the damped natural frequency of the filter and load, the load current and voltage will be a relatively pure sinusoid at that frequency. With the switching frequency equal to the natural (resonant) frequency, the inductive and capacitive reactances cancel out, so the load looks resistive and the maximum possible energy is transferred to it. We say that the voltage gain of the resonant tank is unity under these conditions. By this, we mean that the AC voltage across the resistive load (blue) is equal to the amplitude of the fundamental If the capacitor values are chosen such that the period B is large with respect to the (~10 nanosecond) switching time, the voltage across S1 at the time it opens will be effectively zero – C1 will hold the voltage across S1 to zero while it opens. At the start of period C, C1 is fully charged to Vsrc and C2 is fully discharged. The still-positive load current now commutates to the freewheeling diode, D2. At this time, S2 can be closed while the voltage across it is zero. When the load current reverses at the start of period D, S2 is closed, ready to take the load current for the bulk of its negative excursion. At the start of period E, S2 is opened, while C2 holds the voltage across it to zero. The capacitors support the load current until the start of period F, when the freewheeling diode, D1, takes over. This is when S1 is closed, while its drain-source voltage is zero. The upshot of all this is that both switches only ever open or close with zero voltage across them, resulting in very low switching loss. The caveats to this are that the device switch-off time is small compared to the charge/ discharge times of C1 and C2, and that there is enough phase lag that the freewheel diodes are conducting when the switches are on. The former is not such a challenge, since the switching time is short, but the latter means that we cannot operate too close to natural frequency so the filter inductance remains high enough. Resonant DC-AC converters like this are pretty common – for example, most induction cooktops work this way. A typical large domestic induction cooktop contains resonant converters capable of a power output up to 7kW at frequencies in the 20-100kHz range. This would not be practical without zero-voltage switching. Fig.5: with the addition of capacitors across the switches and a short deadtime when both switches are off, we can achieve almost lossless switching. The switching frequency must always be a little above the natural frequency for this to work. Resonant DC-DC converters You could also imagine rectifying and filtering the output of a resonant DC-AC converter, perhaps after passing it through a transformer, to produce a DC output, as in Fig.6. Frequency modulation could be used to control the resulting DC output voltage. We can think of this converter as a series of four blocks, each with its own voltage gain. The product of these gains is the voltage transfer function of the converter: Vl ÷ Vsrc = Gi Gt Gx Gr. siliconchip.com.au Fig.6: a resonant DC-DC converter can be thought of as four distinct blocks, each with its own gain. This simplifies the analysis enormously. Australia's electronics magazine May 2026  79 Calculating some of these gains is easy. The inverter puts out a square wave with a peak-to-peak amplitude of Vsrc, so an amplitude of ½Vsrc. The current is sinusoidal, so only the fundamental component of this voltage can transfer real power. We have seen many times before that the amplitude of the fundamental frequency of a square wave is 4 ÷ π times its amplitude. Since the amplitude is ½Vsrc, the gain through the inverter must be Gi = 2 ÷ π. The gain of the tank is much more complex. I won’t go through the derivation (life is too short as it is), but it can be shown to be the ugly expression under the resonant tank block in Fig.6. The important thing to note is that the tank gain depends on the ratio of the damped-to-undamped natural frequencies and the Q of the tank. We’ll look into this more when we get to an example. The transformer’s voltage gain is trivial to calculate – it is just the turns ratio, as you would expect. Calculating the rectifier’s gain is a bit harder, but not much. Fig.7 shows how. The resonant tank current driving the transformer primary will be sinusoidal, so we can model the transformer’s secondary current as a sinusoidal current source, is, with some amplitude I, which will depend on the primary current and the turns ratio. The waveforms associated with this simplified circuit are shown on its right. If we assume the filter capacitor is large enough to make the voltage ripple negligible and the diodes are ideal, the transformer secondary voltage vs will be a square wave with amplitude Vl. Because is is sinusoidal, only the fundamental component of vs can contribute real power to the load. Again using the relationship for the fundamental of a square wave, the gain of the circuit Vl/vs(1) is π ÷ 4. We also need to work out the equivalent AC resistance of the rectifier and load. This is important because it is this resistance, seen through the transformer, that loads the resonant Fig.7: this diagram shows how we calculate the equivalent AC resistance of the rectifier filter so we can understand the damping seen by the resonant tank. Fig.8: the curves show the tank gain vs normalised frequency for various values of Q. The example in the text operates in the region bounded by the dotted lines and the Q=1 and Q=4 curves. 80 Silicon Chip Australia's electronics magazine tank and determines its damped natural frequency and Q, both of which will affect the tank gain. Dividing vs(1) by the secondary current gives an equivalent AC resistance of the rectifier and filter of R(ac) = (4 ÷ π) × (Vl ÷ I). Expressed in terms of the converter’s power output, R(ac) = (8 ÷ π2) × (Vl2 ÷ P). Noting that the last bracketed term is equal to the load resistance, R(ac) = (8 ÷ π2) × Rl. A practical example We now have all the equations we need to look at a practical design example. There is not enough space here for a comprehensive design exercise, but I want to show how one would approach such a design. Let’s imagine we are building an isolated resonant DC-DC converter to operate from rectified mains and deliver 10V DC at 20A (so 200W) into a resistive load. The input voltage range should be 300-400V to accommodate a range of mains voltages (let’s not worry about supporting 110-120V AC mains just yet). Because we are using the frequency to control the output power, we need to specify a minimum load so the frequency range is bounded at both ends. We will use a minimum load of 5A (50W) for this exercise. We will use above-resonance control with a target switching frequency in the range of 500kHz to 1.5MHz, or thereabouts. I will break the design up into steps. 1. We can start by calculating the maximum and minimum load resistances corresponding to the minimum and maximum output currents: Rl(min) = 0.5W and Rl(max) = 2W. We can also choose an undamped natural frequency at the low end of our desired range, say 600kHz or 3.77 × 106 radians per second. 2. We have to design the transformer turns ratio so we can achieve the desired output voltage when the source voltage is at its minimum. The minimum DC voltage times the inverter gain Gi gives us a minimum input voltage of 191.0Vrms. On the other side of the transformer, the 10V output voltage divided by the rectifier gain Gr tells us that the fundamental of the secondary voltage must be 12.7Vrms. The ratio of these values gives us a transformer gain Gx (secondary to primary turns ratio) of 0.067. We actually need a bit more gain than this because I have neglected the rectifier siliconchip.com.au siliconchip.com.au 11V V(vl) 10V 9V 8V 7V 6V 12V 10V 8V 6V 4V 2V 0V -2V -4V -6V -8V -10V -12V 250μs V(vs1)-V(vs2) diode drops and any other losses. I will therefore use a nice round turns ratio of 0.1 (ten primary turns for every secondary turn). 3. Now we can calculate the required tank gain. This is easy because we know the inverter gain, the transformer gain, the rectifier gain and the required end-to-end voltage gain (Vl/Vsrc). Because we have a range of input voltages, we will also have a range of tank gains. It turns out that the tank gain Gt has to range between 0.5 and 0.67. 4. The last thing we have to do before we can calculate the component values is to work out what the load resistance looks like from the primary side of the transformer. This is the resistance that will load the resonant circuit. We saw from the analysis of the rectifier that the secondary-side AC resistance of the load is (8 ÷ π2) × Rl. This transforms our 0.5W and 2W minimum and maximum load resistances to 0.405W and 1.62W respectively. We then have to reflect these resistances through the transformer ratio by multiplying them by (N1 ÷ N2)2, which just means multiplying them by 100 in our case. The effective resistance loading the tank is therefore in the range of 40.5W to 162W. 5. We calculate the resonant tank component values based on the Q. The minimum Q occurs when damping is highest and the resistance is at its maximum, corresponding to light loading on the converter. We can just choose the minimum Q to be 1 and calculate the resonant inductor from Q = (ω0L) ÷ R. Rearranging to make L the subject and plugging in the other values (ω0 = 3.77 × 106 radians per second and R = 162W) gives an inductance of 43.0µH. We can then calculate C from the relationship ω0 = 1 ÷ √LC to give 1.63nF. 6. Finally, we can calculate the maximum Q, which occurs when the load is heaviest and the resistance load on the tank is lowest. We can use the same Q = (ω0L) ÷ R formula, this time plugging in the inductance we just calculated and the 40.5W minimum resistance. This gives us a maximum Q of 4, which is not unreasonably high. 7. You could use the ugly formula for tank gain in Fig.6 to calculate what this means for the damped natural frequency, but it is probably easier to follow if you look at the graph in Fig.8. This plots the tank gain vs the normalised frequency (the ratio of 251μs 252μs 253μs 254μs 255μs 256μs 257μs 258μs 259μs 260μs 261μs 262μs 263μs 264μs 265μs 266μs 267μs 268μs 269μs 270μs Fig.9: this simulation of the example resonant DC-DC converter agrees with the calculations. The upper green trace is the output voltage and the lower mauve one is the transformer secondary voltage. damped natural frequency to the natural frequency) for various values of Q. Our converter will operate in the region bounded by the two horizontal dotted lines (tank gain of 0.5 to 0.67) and the curves corresponding to Q=4 (purple) and Q=1 (blue/cyan). The tank gains correspond to the range of input voltage and the Q values correspond to the load resistance range. We can then read off the minimum and maximum normalised frequencies from the horizontal axis. I have marked these points with large dots. In this example, we expect the resonant frequency to range from 1.15ω0 to 2.1ω0. This corresponds to a frequency range of 690kHz to 1.24MHz. Results I find this type of graph very intuitive. The lowest switching frequency corresponds to a heavy load, low input voltage scenario. The highest switching frequency corresponds to the lightest load and highest input voltage scenario. You can see now why we have to set a minimum load – the switching frequency will go through the stratosphere if the load resistance gets too high. I could not resist simulating this circuit, as shown in Fig.9. The inverter block on the left just contains a behavioural voltage source that produces a 50% duty cycle square wave with the frequency and amplitude specified on the front. The resonant Australia's electronics magazine tank and transformer are obvious, and the rectifier block consists of a full-bridge of ideal diodes and a 10µF capacitor. The simulation run below the schematic was at the highest load, lowest input voltage operating point. The results are a bit unspectacular, with the DC output voltage in green and the transformer secondary voltage in purple. However, it does confirm that this switching frequency is roughly correct to achieve the output voltage we desire. There is obviously a lot more to designing a resonant converter, especially one at this power level. In fact, this article has just given a small introduction to resonant and soft switching converters; there are countless variations out there, including some quite novel and interesting circuits. Conclusion This article concludes our series on power electronics. We have covered a lot of ground, including DC-DC, AC-DC and DC-AC converters. We have touched on control systems, magnetics and EMI filtering, and with this article, resonant converters. As I stated at the outset, this series was not meant to be a university-style course on power electronics. Rather, I hope I have provided some insights and a few tools and techniques that may be useful in exploring this endSC lessly fascinating topic. May 2026  81 Installing a Hidden CB Radio in your Car by Julian Edgar You can improve your safety and convenience when driving on country roads with a near-invisible radio. Shown here is a GME all-in-one CB radio. Using this type of design means you only need space on the dash or centre console for the handheld microphone. The rest of the electronics is housed in the small box that is easily tucked away. M any people don’t realise that having a CB radio in a car can be very beneficial, especially in rural Australia. Such a radio can be nearly invisible, both in terms of occupying dashboard space and the presence of the antenna. Safety and convenience Nearly every truck in Australia is fitted with a UHF CB radio. They’re used by the driver when the truck is entering a building site (that’s why you see signs like “UHF 21” on entrance gates to such sites). More relevant to us, on country roads, they’re set permanently to Channel 40. Unlike in old movies (“Breaker, breaker, got a copy Big Bear”), truck drivers mostly talk about road hazards, warning other trucks of the problems they’re about to encounter. This makes listening on a CB radio incredibly useful for anyone who drives on rural roads. I have used CB radios in nearly all my cars of the last 40 years and, over that time, I have been warned 82 Silicon Chip of thousands of road hazards. That includes car and truck accidents, floods, vulnerable touring cyclists, vehicles broken down but not sufficiently pulled off the road, road works, wide loads, trucks with dangerously loose tie-down straps and chains – the list goes on and on. I have also used the radio to tell trucks their rear lights aren’t working, to warn them of hazards I have seen that await them, and on one memorable occasion, to request a pickup from my broken-down car, at night and over 100km from the nearest town (yes, a truck stopped!). Unlike amateur radio, no license is needed for CB radio operation. You simply buy it, fit it and use it! To anyone used to operating a radio in a formal situation, truckies on CB might sound like anarchy in action – but it isn’t. In fact, the communication is strongly codified by tradition. It’s in cities where (unfortunately) every idiot is on the radio screaming meaningless rubbish. Over time, you get used to listening Australia's electronics magazine for the tone of communications, the radio just burbling away in the background. A driver saying hello to a friend who he (they’re nearly always male) has seen travelling the other way has one tone; the escort vehicle of a wide load warning other trucks that the load is coming through has a quite different tone; and a warning about an accident has a different tone again. As an example of the radio in action, the other day I drove from my home north of Canberra down the Barton Highway towards the city. When I turned onto the highway, I immediately knew that something was up; I heard a snatch of conversation where a driver was asking if traffic was being allowed through. That gave me an indication that there had been an accident and the road may be closed. So it proved. As I got closer, the radio chat increased until, by the time I reached the stopped traffic, I knew the type of vehicles that had been in the accident, the length of the traffic jam and the likely duration of the siliconchip.com.au A UHF CB radio installed on the dash of my MG4 electric car. Glass-mount CB radio antennas are unobtrusive and can be installed in minutes. The antenna cable connection is via a small box that sticks to the inside of the glass – no holes are needed! delay. Coincidentally, as I got to Canberra, there was a further delay; this time I asked what the problem was and was immediately told there had been another car crash. A stealth CB installation Most people don’t want a gigantic antenna on their car – there’s also the hassle of fitting it, trying to get a cable into the cabin and also finding space on the dash for the radio. Luckily, you don’t need any of that. There are two approaches that make fitting a largely invisible CB radio quite easy. The first is to use a glass-mount antenna. As its name suggests, a glass-mount antenna sticks to the front or rear glass of the car. Normally, you place it on the windscreen, high up near the roof. The antenna comprises just a very short whip (typically 200mm long) with a small mounting square at its base that sticks to the glass with strong double-sided tape. Attaching this takes, oh, about 30 seconds! Clean the glass, peel off the backing tape, stick it into place. So, how does the cable connect to the antenna? Don’t you have to drill a hole through the windscreen? No; instead, the connection through the glass is made by RF, with a little rectangular box stuck inside the windscreen at the antenna’s location. To run the small-diameter antenna cable to the box, you simply tuck the cable behind the roof headlining and then down behind the A-pillar moulding. Typically, the provided cable siliconchip.com.au doesn’t need to be cut – any surplus length is just coiled out of sight. Editor’s note – this cable route is also suitable for the power cable on many dash cams. The second approach is regarding the radio itself. The trick is to use a 5W radio where the microphone is an ‘all-in-one’ control. That is, the microphone is also the speaker and has all the radio’s controls and displays on it. Radios of this design have a separate box that houses the main electronics, small enough that it can be easily tucked behind the dashboard or centre console – yes, even in current cars. All you then need to do is to find a source of power (invariably I access this at the back of the cigarette lighter/ accessory power socket) and find a place to mount the compact microphone on the dash or centre console. The radio will have an inline fuse in its power feed, so you don’t even need to add a fuse. Don’t cut the wires at the cigarette lighter socket; just bare a short length of the positive and negative leads and solder the power and ground leads of the radio appropriately. Having said that, you should pull the cigarette lighter fuse first and thoroughly insulate all connections with tape before restoring it. Compared to installing a traditional CB radio and antenna, especially in modern cars, the process is quick and easy. In the past, the bane of a CB radio was engine ignition noise, which can be very annoying and is often quite hard to get rid of. However, in my experience, modern cars are much less likely to generate such noise. My current car, an EV, generates no audible RF noise at all (not even from the inverter) – something I was not sure about before fitting the radio. Conclusion A glass-mount antenna and all-inone CB radio will cost more than a traditional CB antenna and radio. It also won’t have the reception or transmitting range of a large antenna mounted on a bull bar, but it will be absolutely fine for monitoring road conditions and talking to nearby vehicles. If you drive on country roads, a CB is a must-have for safety and convenience. Using an all-in-one radio and glass-mount antenna means that only the closest of observers will even realSC ise you have a radio on board. Squelch and transmission range All CB radios have an adjustable squelch control that quietens the radio unless a signal is received (ie, someone is talking). This means that for much of the time, the radio is silent – it’s not a continual distraction or annoyance. Also, because of the limited range (less than 5km for the set-up described here), when someone does talk, it’s often relevant. Australia's electronics magazine May 2026  83 By Tim Blythman Remote Controller DCC Booster Stepper Motor Driver μDCC Decoder microDCC Decoder μDCC The DCC Decoder design in the December 2025 issue is very small, but sometimes not small enough. The μDCC Decoder is designed to be a bare minimum decoder to take up less space, but we’ve still managed to squeeze in a couple of handy features that make it very useful beyond just Image source: https://unsplash.com/photos/black-model-train-moving-through-a-garden-hc9xarcmpM8 being smaller than its predecessor. W e designed the DCC Decoder, from the December 2025 issue, as a simple, inexpensive but complete unit that can add DCC capabilities to small model railway locomotives in the HO and N scales. As I started adding them to my fleet of models, I realised that I could make a couple of changes that would improve their usefulness. I’m not saying that this design is better or worse than the original Decoder, but it is smaller, and I have added some features that I think might be of interest. I recently made the jump to N scale after previously working with HO scale. With the help of a 3D printer, I started scratch-building some model trams, which are even smaller than trains! I thought that the original Decoder would be a good size for what I wanted to model, but those who have done any work at this scale will know that anything that can save space will Features & Specifications be helpful. So I looked at the earlier design to see what I could take out to make it even smaller. First, I didn’t think that I really needed four function outputs, so I discarded two of them. This removes four resistors and two transistors from the board. Next, I removed the circuitry to sense the incoming supply voltage; two more resistors removed. This means that the μDCC Decoder has only two function outputs and does not have the ability to compensate for supply voltage changes. I also figured I could do without the 100nF capacitor on the microcontroller since the micro would be close enough to the existing 10μF regulator output filter capacitor. Hardware-wise, these are pretty much the only differences between the original Decoder and the μDCC Decoder. The newer board is only 12 × 18mm, down from 13 × 28mm; only In model railways, smaller is generally better. The μDCC Decoder is only 12mm × 18mm with two function outputs and even has a basic sound function. 🛤 Size: 18 × 12 × 4mm 🛤 Two 100mA function outputs 🛤 Sound output 🛤 Standard DCC features like the December 2025 DCC Decoder 84 Silicon Chip Australia's electronics magazine 60% of the area! Fig.1 shows the circuit diagram, and you can see that it really is just a cut-down version of the earlier design. It looks like there are some unused pins that are wasted, but I have redeployed I/O pin 11 to supply the 3.3V reference that came directly from the 3.3V regulator in the earlier design; the firmware simply holds this at a high level (3.3V) at all times. This avoids an awkward trace that would otherwise have had to cut across the board. Having a few unused pins made the PCB trace routing easier and more compact, so it actually ended up being a good compromise. I have made some extra signals available on the RA0/PGD and RA1/PGC pins; they have been chosen mainly because they already have external connections available at the ICSP (in-circuit serial programming) header. Just like in the earlier design, track power is rectified by diode bridge BR1. REG1 provides 3.3V to power the microcontroller. The DCC signal polarity is sensed via the two 100kW resistors, and the micro drives the outputs on pins 2, 3, 5 and 6 to control transistors Q1 and Q2 and motor driver IC2. These would be connected siliconchip.com.au Fig.1: the μDCC Decoder circuit is very similar to the December 2025 DCC Decoder, with a few components removed. The 3.3V reference for the motor driver IC comes from a pin on IC1 to simplify the PCB routing. to accessories (such as lights) and the locomotive motor, respectively. The 100W resistor and series diode D1 allow a capacitor to be fitted to provide ‘keep-alive’ power that can help compensate for intermittent contact due to dirty track. In other respects, operation is the same as the earlier design. Bonus features The PIC16F181xx family of chips has an 8-bit DAC (digital-to-analog converter) that has reasonable drive strength. It isn’t specified what current it can deliver, but tests indicated that it would be possible to source and sink up to 20mA. After removing excess features from the earlier Decoder firmware, the PIC16F18126 has around 12kB of unused flash memory, which is enough to hold a fraction of a second of 8-bit sampled audio data. So I investigated driving a small piezo transducer with the DAC to reproduce audio. The DAC output is directed to pin 13, since this is broken out amongst the ICSP pins. It has a ground pin next to it on the ICSP header, so it’s fairly easy to make the necessary connections to the transducer. An electromagnetic siliconchip.com.au speaker will likely have an impedance that is too low to work; you must use a high-impedance device like a piezo transducer. The piezo I tested measures 9mm square and 2mm thick. Its model code is in the parts list; I’ve managed to squeeze this device into several N-scale models. The piezo transducer has a peak response around 4kHz, which is quite high, and I quickly found that high-pitched sounds were reproduced much better than lower-­ pitched sounds. This means that a high sampling rate is needed; fortunately, the DCC firmware already includes a 22μs timer interrupt, which (at 45.4kHz) is fairly close to the 44.1kHz sample rate used in audio from sources like CDs. This made it easy to experiment with existing samples. So, onboard audio production is possible, but the result is not hifi! Still, I was able to recreate some recognisable sounds for a model railway. The best sound I could recreate was a tram bell. This could also pass for the level crossing bell used on some diesel locomotives. The μDCC Decoder would also work well as a stationary decoder for a level crossing’s lights & bells. I figured that a steam locomotive whistle might also be sufficiently highpitched to work, so I’ve synthesised a sample that emulates this. We’ve made a recording of these sounds being played by the μDCC Decoder, so that you can hear for yourself. It’s an MP3 audio recording from siliconchip.au/ Shop/6/3587 The 8-bit microcontroller has modest processing power and would struggle to mix the two sounds, so we have DCC PROJECT KITS DCC Base Station, January 2026 (SC7539, $90) DCC Remote Controller, February 2026 (SC7552, $35) DCC Booster, March 2026 (SC7579, $45) DCC Stepper Motor Driver & Decoder, April 2026 (SC7601, $30) microDCC (μDCC) Decoder, May 2026 (SC7617, $25) includes all the parts and the optional piezo (wire not included). Specify if May 2026  85 Australia's electronics magazine you want a bell or whistle sound programmed into the microcontroller. Pay close attention to the resistor values and component polarities. Fortunately, the two capacitors are of the same value. The regulator and transistors are all in SOT-23 packages, so be sure not to mix them up. Screen 1: It’s incredible what is possible with model trains; tiny LCD modules like these add another element of realism. The CV48 serial data feature is intended to control features that don’t map well to traditional DCC function outputs. Source: https://youtu.be/tC_t22RfQ0c created two firmware files: one for the bell sounds and one for the whistle sound. If combined, the samples would also have to be shorter. Sound is controlled by a function output. The bell sound will repeat as long as the function is active, and a cheery “ding-ding” will be heard if the function is held for about half a second. The whistle sound will ramp up and keep playing until the function is switched off, after which it quickly decays to silence. We’ve also added another output to the μDCC Decoder. It is intended to allow communication with another microcontroller that could implement other features. One application that came to mind is a form of headboard or destination display, such as a second microcontroller driving a small OLED module or LCD. When it receives a byte over the serial link, it can update the display. This would only happen occasionally, so would be easy to control with the Base Station’s CV programming page. The YouTuber diorama111 has implemented this type of display in HO scale models, although it is controlled through an infrared remote control. Screen 1 shows a still from the video at https://youtu.be/tC_t22RfQ0c The output is a UART (serial data) signal that is available on RA1/PGC, the other I/O pin that is free on the ICSP header. It operates at 3.3V, 9600 baud with eight data bits. This protocol EEPROM location Stepper Driver μDCC Decoder Extra output Decimal Hex 86 DCC Decoder CV Default Hex CV Default Hex CV Default Hex 0 0x00 29 2 0x02 29 2 0x02 29 2 0x02 1 0x01 1 3 0x03 1 3 0x03 1 3 0x03 2 0x02 19 0 0x00 19 0 0x00 19 0 0x00 3 0x03 18 0 0x00 18 0 0x00 18 0 0x00 4 0x04 17 192 0xC0 17 192 0xC0 17 192 0xC0 5 0x05 2 0 0x00 3 0 0x00 2 0 0x00 6 0x06 3 0 0x00 4 0 0x00 3 0 0x00 7 0x07 4 0 0x00 5 64 0x40 4 0 0x00 8 0x08 5 0 0x00 33 1 0x01 5 0 0x00 9 0x09 6 0 0x00 34 2 0x02 6 0 0x00 10 0x0A 33 1 0x01 35 0 0x00 33 1 0x01 11 0x0B 34 2 0x02 36 0 0x00 34 2 0x02 12 0x0C 35 4 0x04 37 0 0x00 35 4 0x04 13 0x0D 36 8 0x08 49 255 0xFF 36 0 0x00 14 0x0E 37 0 0x00 50 255 0xFF 37 0 0x00 15 0x0F 49 255 0xFF 11 0 0x00 49 255 0xFF 16 0x10 50 255 0xFF 50 255 0xFF 17 0x11 51 255 0xFF 11 0 0x00 18 0x12 52 255 0xFF 19 0x13 11 0 0x00 20 0x14 Chip47 0 Silicon 0x00 TableAustralia's 1: CV toelectronics EEPROMmagazine mapping is simple and common enough that any microcontroller should be able to receive it and provide some custom functions. It is controlled through a virtual configuration variable (CV), CV48. Operations mode programming allows this CV to be programmed ‘on the mainline’. Any time the μDCC Decoder receives a write command to program CV48, it sends the corresponding data byte over the serial output. That’s all there is to it. These pins are shown on the overlay/wiring diagrams later in the article. If you don’t want or need these two features, you can just leave these pins disconnected. Construction Like the earlier Decoders, this is a small design using surface-­mounting parts, so you’ll need the gear and expertise to handle that. Many of the comments from the DCC Decoder also apply here. For example, you can increase the value of the 0.68W resistor to reduce the motor current limit, although you should not decrease it below 0.68W. The μDCC Decoder is built on a double-­ sided PCB coded 09111247 that measures 12 × 18mm and is 0.8mm thick. Work through the overlay diagrams, Figs.2 & 3. Start with the side that has IC2 and BR1. Solder these first, noting their polarity. Follow with D1, making sure its cathode stripe is nearest the pads marked T. Also on this side is one of the 10μF capacitors, right next to the bridge rectifier outputs. The two 100kW resistors, the 100W resistor and the 0.68W resistor are also on this side of the PCB. Flip the board over and fit REG1 (near IC1) and Q1 and Q2 (near the edge of the board). Solder IC1 in place with its pin 1 marker nearest to REG1. The resistors on this side are the 10kW and 10W siliconchip.com.au Programming a DCC Decoder without a DCC Programmer We’ve presented a thorough series of DCC system components over recent issues, including the Base Station hardware, which has comprehensive DCC programming capabilities. But it occurred to us that many of our readers will probably have hardware at their disposal that will allow programming our Decoders (from this series) without a dedicated DCC programmer. Our Decoders are all based on PIC microcontrollers, which are easily programmed with devices like the various PICkit programmers or even the Snap programmer (which we now carry in the Silicon Chip Online Shop at siliconchip.au/Shop/7/7588). The configuration variables (CVs) that are involved in Decoder programming are simply locations in EEPROM and thus they can be changed with the appropriate PIC programming hardware. So this guide explains how to program the CVs in our Decoders using a PIC programmer. Table 1 shows which CVs correspond to which EEPROM address on each Decoder. Below we explain how to modify the EEPROM values for programming. We’ll assume you’ve used a programmer like this before, and know how to make the necessary wiring connections to program a PIC microcontroller. It’s also assumed that you understand the CVs that you want to program. Read-only locations like CV7 and CV8 are not implemented in EEPROM, so cannot be modified. Of course, we have provided the source code for all three projects, so you can modify the source code and recompile the project (using MPLAB X IDE) to make those or any changes you like. The default values for all the CVs are set near the start of the dcc.h file. If you are simply looking to adjust some of the CVs, we recommend just using the MPLAB IPE (integrated programming environment) software. Screen 2 shows the IPE with the PIC16F18126 selected; as you would need for any of the Decoder projects. Select the appropriate HEX file by using the Browse button and then open the EEPROM view from Window → Target Memory Views → EE Data Memory. From here, you can edit the EEPROM values directly. The hexadecimal values in Screen 2 correspond to the original DCC Decoder from December 2025. Editing the EE Data Memory window will not directly change the HEX file, but you can export the edited file from the File menu as a new HEX file. The exported HEX file can be reloaded later using the Browse button noted above. When you have made the necessary edits, hook up your programmer to the Decoder, press Connect and then press Program to change the values stored on the chip. Remember that you should not have anything else connected to the ICSP pins during programming. You can also download the contents of the PIC’s non-volatile memory (including flash memory, configuration bits and EEPROM) with the Read button. You can then edit the EEPROM values and program the new values back into the chip. While this is a slightly convoluted method of CV programming, you can also use it to save and restore program memory images and CV settings of the decoders for safekeeping. We had a detailed guide to CV programming in the Getting Started with DCC guide in the January 2026 issue (siliconchip.au/Article/19560). ◀ Screen 2: The MPLAB IPE can be downloaded as part of the MPLAB X IDE and provides an interface for programming PIC microcontrollers (and other Microchip parts). The EEPROM entries at the bottom match the DCC Decoder, with other locations left blank (0xFF). parts, so take care not to mix them up. Don’t forget the other 10μF capacitor. Clean the board of any excess flux, inspect the board and allow it to dry. If necessary, you can program the chip at this point. Note that you cannot use a PIC16F18124 or PIC16F18125 for this project, since the larger flash memory of the PIC16F18126 is needed to store the audio samples. You shouldn’t need to program the chip if you have purchased it from the Silicon Chip Online Shop. Also be sure not to connect the piezo transducer or any other circuitry to the ICSP pins (except a programmer) siliconchip.com.au during programming, since this will interfere with the programming process. The remaining steps for testing and wiring the μDCC Decoder to a locomotive are much the same as the DCC Decoder. Operation The μDCC Decoder operates in much the same fashion as the DCC Decoder from December; the implemented CVs all work the same. We’ve given the μDCC Decoder a model ID (CV7) of 0x5E (94 in decimal) to differentiate it from the other two Decoders. Australia's electronics magazine The other main differences (compared to the DCC Decoder) are that it lacks CV47, CV51 and CV52. CV47 is for voltage compensation, which the μDCC Decoder can’t do. CV51 and CV52 are not needed, since the corresponding function outputs have been deleted. The EEPROM Mapping panel in the December issue has more information about the CVs, see the panel on programming with a PIC programmer. The audio output is equivalent to the green wire function output (F1) in other decoders. There are no effects that can be applied, but it’s possible to May 2026  87 Figs.2 & 3: the external connections to the μDCC Decoder are via bare solder pads as shown here. We have been able to keep the main DCC connections on the same side of the PCB, with the audio output using some of the ICSP pads on the reverse. Parts List – microDCC (μDCC) Decoder 1 double-sided 12 × 18mm PCB coded 09111247, 0.8mm thick 1 PIC16F18126-I/SL 8-bit microcontroller programmed with 0911124G.HEX (bell sound) or 0911124W.HEX (whistle sound), SOIC-14 (IC1) 1 DRV8231DDAR motor driver IC, SOIC-8 (IC2) 1 MCP1703A-3302 3.3V LDO linear regulator, SOT-23 (REG1) 2 2N7002 N-channel Mosfets, SOT-23 (Q1, Q2) 1 MBS4 or CD-MMBL110S 1A SMD bridge rectifier (BR1) 1 1N5819WS 40V 1A schottky diode, SOD-323 (D1) 1 2cm length of 20mm diameter heatshrink tubing (to insulate Decoder) 2 10μF 25V X5R SMD M2012/0805 size MLCC capacitors 1 Same Sky CPT-9019A-SMT-TR piezo transducer (optional) various lengths of wire as needed Resistors (all SMD ±1%, M2012/0805 size, ⅛W unless noted) 2 100kW 3 10kW 1 100W 2 10W 1 0.68W ¼W reduce the volume by adding a resistor in series with the transducer. The default setting maps the audio to the F1 function output, so you can use the F1 control on the Base Station to test the sound. The mapping is due to the value of 4 appearing in CV35. You can use other function outputs to control the audio by ORing 88 Silicon Chip CV33-CV37 with a value of 4. For example, to use F2 to control it, program CV36 with the value 4. CV48 is not mapped into EEPROM, so it can’t be read back. It will respond to writes in all programming modes, but we expect it will be most useful in operations mode on the main track. Base Stations will typically send Australia's electronics magazine repeated programming packets, so the μDCC Decoder may deliver multiple serial bytes in response to this. Custom sounds It’s possible to change sounds, but you will need to recompile the project files to do this. The audio samples and config are in audio.c and audio.h. The maximum sample size is around 13kB, which corresponds to around 300ms at 44.1kHz. Be sure to select compiler optimisation level 2, which is available even with a free license. The samples are effectively 8-bit unsigned values, but they should start and end with a zero value (by ramping up from zero and down to zero) so that the DAC idles at 0V when not playing. This will prevent power supply noise from being produced at these times. There are options to play the audio either as a one-shot or as a loop. Note that the one-shot will repeat if the function stays on. Use the bell sound as a template for one-shot sounds and the whistle as your guide for looping sounds. For looping, you’ll need to set the AUDIO_ LOOP_START and AUDIO_LOOP_ END points. During playback of a looping sound, the sound will play up to the loop end point and jump back to the loop start to maintain a continuous sound. Our process to generate the samples is to use Audacity (free software) to create an 8-bit, 44.1kHz mono WAV file. We then use the HxD hex editor program to strip out the 44-byte WAV header and export the file contents as a C byte array that can be pasted into the assignment for the audioData variable in audio.c. The code can automatically work out the data size to stop playback when the end of the data is reached. The available sample space will be slightly smaller for looping sounds, since there is extra code needed to handle the looping that will use up some of the flash memory allocation. Summary While I had intended this design to allow me to add DCC to some of my smaller models, I’m quite proud of being able to cram some simple sound effects and other features into a tiny 8-bit microcontroller. I’ve built a few of these μDCC Decoders and now all my N scale models are soundSC equipped! siliconchip.com.au Subscribe to APRIL 2026 ISSN 1030-2662 04 The BEST DIY Projects! 9 771030 266001 $14 00* NZ $14 90 Calliope A mplifier 100W INC GST INC GST Stepper Motor Driver DC or DCC control for model railways Australia’s top electronics magazine PicoSDR Silicon Chip is one of the best DIY electronics magazines in the world. Each month is filled with a variety of projects that you can build yourself, along with features on a wide range of topics from in-depth electronics articles to general tech overviews. 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To start your subscription go to siliconchip.com.au/Shop/Subscribe Review by Tim Blythman BrisbaneSilicon ELM11 Microcontroller Board The inexpensive ELM11 development board from BrisbaneSilicon uses the Lua programming and scripting language and is fairly inexpensive. It’s great to see this type of thing being designed in Australia, so we were curious to try it out. T he folks from BrisbaneSilicon (https://brisbanesilicon.com.au) work in FPGA (field programmable gate array) and embedded systems engineering. They contacted us to see if we were interested in trying out their ELM11 microcontroller board. ELM stands for Embedded Lua Machine and, as you might expect, it can be programmed using the Lua language. BrisbaneSilicon sent us a couple of ELM11 boards to experiment with; here is what we found. Lua Lua is an interpreted scripting language that was originally developed to streamline data entry at a Brazilian petrochemical company. It has developed into a simple yet powerful language that is used in many places where a scripting language is needed. That includes games and embedded (microcontroller) environments. Scripting languages are generally easier to use and develop for, especially for particular applications, with the trade-off being that they are usually slower and more memory intensive than compiled languages like C or C++. Lua is the Portuguese word for moon; one of Lua’s predecessors was named SOL, or sun. Lua’s interpreter is written in the C programming language, so is easy to port to platforms that have a C compiler. It is also designed to easily interface with C code, so it can be used to add scripting to projects written in C. You can read more at https://lua.org/about.html We’ve written a separate panel about the Lua language for those who want to know more. The ELM11 presents a REPL interface, where REPL stands for The ELM11 is a compact and tidy development board that provides an embedded interpreter for the Lua programming language. There isn’t much on the underside of the board apart from pin markings. All the components are on the top of the board, including two tactile pushbuttons and numerous LEDs. The ELM11 includes a Gowin GW1NR FPGA and a separate microcontroller that provides a virtual USB-serial port and can also reprogram the FPGA chip. 90 Silicon Chip Australia's electronics magazine read, evaluate, print and loop. You can also write and then run complete programs for more complex tasks. In this regard, it is similar to devices like the PicoMite running MMBasic. MicroPython is similar; it can run on many microcontroller boards, including the Raspberry Pi Pico. All these devices and languages allow you to enter simple commands or write and run complex programs. The ELM11 The ELM11 measures 60 × 26mm and has two rows of 18 pins on a 0.1inch (2.54mm) pitch with 0.9 inches (22.86mm) between the rows. This is a fairly standard layout for modern development boards, allowing them to be easily used with breadboards or prototyping PCBs. The pin headers are provided loose and need to be soldered to the module. The ELM11 is shown in the photos. It has a USB-C socket, which is good, since they are much more robust than the micro-B USB sockets that are sometimes seen on boards like this. Interestingly, the large chip that you might expect to be the microcontroller is in fact a Gowin Semiconductor GW1NR FPGA. An FPGA is made of many logic elements that can have the connections between them rerouted after production. It can be compared to how you might program a microcontroller to customise its operation. Microcontrollers are also made of logic elements, so an FPGA can be programmed to behave as a microcontroller, among many other things. The GW1NR comes in a QFN-88 siliconchip.com.au package (quad-flat no-leads with 88 pins) and incorporates 8640 LUTs (lookup tables) with 8MiB (64Mib) of RAM. It also has a smaller amount of BRAM (block RAM) and includes flash memory to store the configuration bit stream. There is a separate Puya P25Q32SH 4MiB (32Mib) flash memory chip in a SOIC-8 package, which is available as non-volatile storage for the Lua interpreter. The smallest QFN chip is a TMI7003 three-channel power management IC that incorporates a buck regulator controller. It provides the multiple supply rails needed by the FPGA chip. The remaining QFN chip is a BL702 RISC-V microcontroller that is used to provide a USB interface to implement a virtual serial port interface for communicating with the Lua interpreter. It also provides a JTAG programmer that can be used to reprogram the FPGA. There are 36 pins available on the two headers, four of which are for power: 3.3V, 5V and two ground pins. The remaining pins are numbered from one to 32. Sixteen (1-16) of these pins are for general purpose I/O, while the remainder are labelled as an I/O bus. The I/O pins operate at 3.3V levels. Fig.1 shows the pin mapping of the ELM11, including the peripherals that can be mapped to each pin. The mapping is set by the FPGA configuration, and it appears that different ‘hardware overlays’ are possible. This can change which peripherals are available on which pins, amongst other features. There are also several LEDs on the board with different functions. Three are configured to reflect the status of I/O pins 1, 2 and 3, making it straightforward to start blinking the LEDs with Lua, without connecting any external hardware. There are two small tactile switches. One can be used to reset the ELM11, while the other can be detected on I/O pin 1. This combination of a GW1NR FPGA and a BL702 microcontroller can also be found on the Tang Nano 9K development board. More information on the Nano 9K can be found at siliconchip.au/link/ac9z Using the ELM11 The ELM11 presents a virtual serial port to communicate with the Lua REPL interface. It operates at 115,200 baud, 8 bits, no parity and one stop bit. Screen 1 shows the prompt after booting, plus a few commands and their responses. We used the Tera Term terminal program under Windows. We found it easy to enter Lua statements at the terminal prompt; the results are printed back to the terminal. The import statement is needed to load the functions used to access features like the GPIO pins. A simple import(“all”) can be used to quickly load all extra functions, although you can also import individual functions to reduce memory usage. BrisbaneSilicon has provided some simple code examples that can be used in the REPL. They are set up to be copied and pasted directly into a terminal program and can be found at https://brisbanesilicon.scrollhelp.site/ emblua/example-usage We found that we had to set a 100ms per line delay in TeraTerm to allow the processor to complete the import command for multi-line examples; this appeared to be more than sufficient for other commands. This setting can be found in TeraTerm’s menu under Setup → Serial port… → Transmit SPI UART PWM Function Pin Pin Function TX TX PWM GPIO 1 19 I/O BUS CS, CLK, TX RX PWM GPIO 2 20 I/O BUS CS, CLK, TX TX PWM GPIO 3 21 I/O BUS CS, CLK, TX RX PWM GPIO 4 22 I/O BUS CS, CLK TX PWM GPIO 5 23 I/O BUS CS, CLK RX PWM GPIO 6 24 I/O BUS CS, CLK, RX TX PWM GPIO 7 25 I/O BUS CS, CLK, RX RX PWM GPIO 8 26 I/O BUS CS, CLK, RX TX PWM GPIO 9 27 I/O BUS CS, CLK, RX RX PWM GPIO 10 28 I/O BUS CS, CLK TX PWM GPIO 11 29 I/O BUS CS, CLK RX PWM GPIO 12 30 I/O BUS TX PWM GPIO 13 31 I/O BUS RX PWM GPIO 14 32 I/O BUS TX PWM GPIO 15 33 I/O BUS RX PWM GPIO 16 34 I/O BUS GND 17 Fig.1: The data sheet includes this I/O pin 5V 18 map that also shows the layout of the main features of the board. The button at upper left is RST and the other one to its right is BTN1. Note that the pin numbering shown here is different to that printed on the PCB silkscreen. 35 GND 36 3.3V siliconchip.com.au May 2026  91 Australia's electronics magazine delay. The GPIO and PWM examples are designed to use the onboard LEDs. Even without having much knowledge of the Lua language, it was simple to copy and paste example code from the BrisbaneSilicon website and see the results on the LEDs and console immediately. The library functions are detailed at https://brisbanesilicon. scrollhelp.site/emblua/api There is also a so-called Command Mode, which is used to access system and configuration settings. You can also use it to do things like upload programs. A Python program is required on the host computer to upload the program over the serial port. Programs can also be run from Command Mode. We tested the program upload utility and found it worked well enough, although it is necessary to disconnect the terminal program to allow it to access the serial port. Complete programs can be found at: https://brisbanesilicon.scrollhelp.site/ emblua/example-programs The reset button can be easily used to reset the processor to get back to a known state. A running command or program can be interrupted by pressing the ‘q’ key. The ELM11 data sheet has more detail on the interface; see https:// brisbanesilicon.com.au/docs/ELM11_ Datasheet.pdf ESR Test Tweezers Complete Kit SC6952: $50 June 2024 siliconchip.au/Article/16289 This kit includes everything needed to build the ESR Test Tweezers. The three resistors and single capacitor needed for calibration are also included. But this kit does not include the CR2032 (or CR2025) coin cell or optional 5-pin header CON1. The board we received is a beta (pre-production) release of the ELM11, and the data sheet notes that some of the SPI and I2C functions are not implemented yet. We were able to bit-bang I2C data using GPIO pins to (slowly) drive a small OLED module. Other I/O features such as PWM (pulse-width modulation) and UART (asynchronous serial) worked as expected. There is also a help statement that prints out a user guide on the serial terminal. The ELM11 platform The ELM11’s architecture has been optimised for working with Lua. BrisbaneSilicon refers to this as ‘hardware acceleration’. The advantage of using an FPGA is that the processor core can be tweaked to improve performance for the intended use; in this case, as a Lua interpreter. The ELM11 data sheet notes that different so-called hardware overlays are available. These appear to include options like different I/O features and processor characteristics. It also appears that it may be possible to configure it with a multi-core processor. Using an FPGA also enables the ability to add other so-called IP cores. These are modular features that can be added to the FPGA fabric and could include things like display and communication drivers or other processors. Some examples are listed at https://brisbanesilicon.com. au/ipcores With its similarity to the Tang Nano 9K, it may also be possible to use the ELM11 as a general-purpose FPGA development board, although we have not investigated this in detail. Conclusion Screen 1: the interactive Lua prompt can be used to enter commands and see responses. The last three commands are all that are needed to light one of the LEDs on the board. 92 Silicon Chip Australia's electronics magazine The ELM11 combines several interesting features. Lua is simple yet powerful, making the Embedded Lua Machine easy to use and versatile. The FPGA platform offers a lot of flexibility in that it can be configured with different capabilities using hardware overlays. Even though we rarely use the Lua language, we found the ELM11 easy to use, with many examples that can be run on just the bare board or with some components on a breadboard. It’s an inexpensive way to learn Lua in general and to provide an embedded environment. The ELM11 is available online from BrisbaneSilicon for US$14.95 (about AU$21) before shipping – see https:// SC brisbanesilicon.com.au/elm11 siliconchip.com.au The Lua Language This is not the first time we have encountered Lua; the Mini Wireless Webserver (using the OpenWRT firmware) in the November & December 2012 issues (siliconchip. au/Series/20) was configured and programmed using Lua. Its utility as a scripting language is well-established, and the open-source OpenWRT router firmware uses Lua extensively. OpenWRT’s web configuration interface is called LuCI (Lua Control Interface) and, as we saw from the Mini Wireless Webserver, Lua can even be used to generate custom web pages. Lua has been used for scripting and automation in computer games since at least 1997, when it was used by LucasArts in the framework of their Grim Fandango adventure game. It is estimated that about half of all Lua users are involved with game development. The NodeMCU project for Espressif microcontrollers (such as the ESP8266 and ESP32) allows boards based on these chips to be programmed using the Lua language. See https://github.com/nodemcu/ nodemcu-firmware In these applications, Lua is used similarly to the likes of Micromite BASIC, PicoMite MMBasic or even MicroPython. If you have seen some Lua code, you might think it doesn’t look very different from these languages. It does have subtle differences, but it is fairly forgiving and easy to learn. Some background is provided at www.lua.org/ history.html The designers have aimed for simplicity of the language, so it is not surprising that it looks like other languages. The webpage above indicates that the optional use of semicolons (as statement separators) in Lua came about to appease users of both C and FORTRAN! A minimal Hello world program looks like this: print(“Hello World”) Lua implements well-understood control structures like if/then/else/ end and while and for loops. The for loop uses the keywords for, do and end; each control structure has a siliconchip.com.au corresponding end statement, so the scope is clear. Interestingly, variables do not have a type, but values do. The types include number, string, function and table. There is also a nil type, which is understood to be the default value of an uninitialised variable. Functions can be defined and can return one or more values; a function can even be assigned to a variable. Lua supports multiple variable assignments in the same statement. Tables are associative arrays; this means that the index does not have to be a number. Tables can be used to implement ordinary arrays, sets, lists, dictionaries, trees and queues. There is a variant of the for loop that can be used to iterate over the items in a table. One thing to watch is that numeric array indexes are 1-based, unlike many other languages (eg C/ C++ are 0-based). So-called meta-tables can be used to override the behaviour of mathematical operators when non-­ numeric arguments are provided. Thus, they can be used to emulate object-­oriented methods. The developers of Lua call these features meta-­ mechanisms. The intent is to keep the underlying language quite simple, but provide a means for a programmer to create complex behaviours when required. These advanced language features might sound intimidating, but if you are looking to use Lua for straightforward scripting, you don’t need to use them. If you are comfortable with the likes of MMBasic, you’ll probably need to do little more than learn a few different keywords and some minor syntax differences. If you have worked with BASIC, C or Python, aspects of Lua like expressions and mathematical operators will appear familiar. Numerical values are typically stored as floating point, but some implementations (including the ELM11) use 32-bit signed integers. It’s worth remembering that Lua code is case-sensitive. Like Python, the language can be extended with the import keyword. For example, the interface for the I/O features of the ELM11 is simply a set of functions that can be imported to make them available to the interpreter. Lua’s simplicity also means that is also renowned amongst interpreted languages for its speed. Summary Lua is an interesting language, and we found it easy to learn the basics. Despite this, it can be extended in multiple ways to provide advanced programming features. Here is a relatively simple sample program: #!/usr/bin/lua print(“Content-type: text/html\n”) print(“<HTML><HEAD><TITLE>Relay control</TITLE>“) print(“</HEAD><BODY>“) local f = io.open(“/dev/ttyACM0”, “r+”) f:write(“quiet\n”) if os.getenv(“QUERY_STRING”):upper() == “ON” then f:write(“D0=1\n”) print(“Relay is now on.”) elseif os.getenv(“QUERY_STRING”):upper() == “OFF” then f:write(“D0=0\n”) print(“Relay is now off.”) else print(“Error.”) end f:close() print(“</BODY></HTML>\n”) This snippet of Lua code was presented in the series on a Mini Wireless Webserver to generate a web page and send data over a serial port to control a relay. Even if you haven’t used Lua before, it’s fairly clear how the program works. Australia's electronics magazine May 2026  93 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. SOT-223 adaptor for amplifier VAS transistors As explained in the Calliope amplifier article (April 2026; siliconchip.au/ Article/20084), it is becoming increasingly difficult to find suitable throughhole transistors for an amplifier’s voltage amplification stage (VAS). That’s because these transistors need a combination of characteristics (moderate current and power handling, wide bandwidth, low capacitance etc) that used to overlap with CRT horizontal output stages. With CRTs no longer being manufactured in any real quantity, such transistors have also met the fate of the dodo. There are still some decent VAS transistors available as SMDs, mostly in the medium-power SOT-223 package. But those won’t easily fit onto existing amplifier PCBs designed for TO-126 or TO-220 through-hole transistors. You can buy SMD-to-through-hole adaptor boards, but they usually aren’t designed to handle devices with any significant dissipation, leading to overheating. This adaptor board design is shown here at 400% scale. It connects the three main pins of the SOT-223 device to three pads that accept a standard 2.54mm/0.1-inch pitch header (straight or right-angled). It also connects the tab of the device to a fairly substantial area of copper, with vias through to the other side of the PCB, where there’s an even larger copper area. This means the transistor can safely dissipate at least 1W, perhaps a little more, which is typical of what’s expected for a VAS transistor. That brings it roughly on par with its TO-126 equivalents, which can handle up to about a watt before they need a small heatsink. The pinout of SOT-223 NPN transistors is almost universally B-C-E. Through-hole transistors are not standardised and can vary, but luckily, most common VAS transistors (including the BF469 and KSC3503 that we’ve used previously) have the E-C-B pinout, which is a mirrored version of this adaptor. To ensure it’s the right way around, mount the adaptor PCB vertically using a right-angle pin header with the SOT-223 device on the side of the adaptor PCB that is where the TO-126 device tab would have previously gone. That should ensure the base, collector and emitter are all connected as expected. You can purchase this PCB from siliconchip. com.au/ Shop/8/7570 You could also use this board for your own devices, as a general-­ purpose SOT-223 adaptor, provided you have the space. That will give you more thermal headroom when working with such devices than standard adaptors. Phil Prosser, Prospect, SA. ($60) Automatic Level Crossing Controller for model railway This controller uses an Arduino Nano module and passive reflective infrared (IR) sensor modules placed an appropriate distance on each side of the crossing to monitor for approaching trains and automatically activate the crossing booms, lights and bells. It operates for trains travelling in either direction. The sensor modules are types commonly available via eBay or Ali­ Express, consisting of an IR LED, an IR phototransistor and an LM339 comparator, with a threshold (sensitivity) that is set via a trimpot. The Arduino “VarSpeedServo” library is used to slow the movement 94 Silicon Chip of the boom servos for a more realistic effect. A separate flasher module using a 4093 quad schmitt-trigger NAND IC was used to simplify Arduino programming, avoiding the use of interrupts or timing loops in the sketch. It alternately drives the common-anode LED crossing lights at approximately 1Hz. The use of opto-isolators at the sensor input pins of the Arduino is a convenient way to overcome any false triggering due to noise pickup in the sensor connecting wiring. At startup, both sensors are checked. They must remain continuously inactive for a period to make sure the crossing is clear before continuing. Australia's electronics magazine When a train is detected by either of the sensors, the crossing is closed. Bell sounds and flashing lights are activated, and there’s a short pause before the crossing booms are lowered. To allow for trains of different lengths, the passage of the train through the crossing section is fully monitored. A timeout with reset will occur if the train, having triggered the ‘approach’ sensor, does not activate the ‘depart’ sensor within a set time. The timeout is adjustable via a trimpot, which is read via an analog port, digitised and remapped to within a range set by maximum and minimum limits defined within the sketch. siliconchip.com.au Once the train has reached and activated the ‘depart’ sensor, that sensor must then remain continuously inactive for a minimum time before the train is considered to have departed and the crossing is then clear. This minimum inactive time requirement allows for breaks in sensor triggering due to the gaps between items of rolling stock and to make sure the train has fully cleared the crossing. The crossing is only then re-opened – the crossing booms are slowly raised, there’s a short pause, then the bell sounds and flashing lights are switched off. There is monitoring for any further, close-following train during the crossing opening sequence, in which case the crossing returns to the closed condition. Crossing bell sounds are achieved using a DFRobot DFPlayer Mini audio module to play a crossing bells audio file from a microSD card. The bell audio file is played using the player’s loop mode, so it repeats continuously until the Player is commanded to stop. In this playback mode, the audio file must be the first file loaded from the microSD card. siliconchip.com.au There are numerous crossing bell-ringing audio files free to download from the Internet. The DFPlayer module’s volume is also adjustable via a trimpot, which is read via an analog port, digitised and remapped to within a range set by maximum and minimum limits defined within the sketch. For more information on the DFPlayer Mini, see the December 2018 issue, pp74-77 (siliconchip.au/ Article/11341). The trimpot adjustments for both timeout and DFPlayer volume control are not dynamic. They are read only once at startup to set their respective parameters. Changing a trimpot setting while the controller is running will have no effect until the power is cycled or microcontroller is reset. However, an extra routine to dynamically set the DFPlayer volume is Australia's electronics magazine included in the sketch startup process. It is invoked if pin D7 is found to be pulled low (switch S1 closed) at startup. This extra routine commands the DFPlayer to play the bell audio file in a loop while continuously reading the volume trimpot setting and using that to adjust the volume. This continues until pin D7 goes high by opening the switch for the resumption of normal operation. If pin D7 is found to be high at startup (switch open), the volume setting routine is skipped. If this feature is not required, pin D7 may simply be left with no connection. You can download the Arduino sketch for this circuit from siliconchip. au/Shop/6/3333 Bob Martindale, Mill Park, Vic. ($120) May 2026  95 Simple battery charging using relay & lamp I built several batteries from rescued good cells from discarded lithium-ion tool batteries and developed this simple charger for them. All relay coils have a voltage potential where the magnetic attraction will no longer hold the contacts closed. This is the dropout (or release) voltage and is fairly constant for a particular relay. A typical Li-ion cell is fully charged when it reaches 4.2V per cell. A 5V relay could drop out at, say, 2.8V (determined by experimentation). A Li-ion battery full-charge voltage is 4.2V multiplied by the number of cells, eg, 25.2V (6 × 4.2V). Add the 2.8V relay drop-out voltage to get 28V; this is the value to adjust the boost module output to. When the battery voltage reaches 25.2V, there is no longer enough voltage to hold the relay in, so it drops out and charging stops. The photos below show a unit I made on a piece of protoboard, with pins that clamp to the boost module output terminals. The adjustable boost module I used was Jaycar Cat XC4609. It is available at a lower price from online suppliers, but once you consider the postage cost, that saves little. Since the module can only provide an output voltage that’s higher than the input, or a little lower, use a phone charger or 5V USB as the power source to enable low enough output voltage settings to charge 1-3 cell Li-ion batteries. To set it up, measure the current battery voltage and adjust the boost module output to 5V higher. Connect the battery, press the start switch and the relay should pull in. The current through the battery is the relay current plus the globe current. Slowly decrease the boost module’s output voltage, and when the relay drops out, note the voltage. The relay drop-out voltage is this voltage minus the battery voltage. For example, if the relay drops out when you reduce the boost module output to 18.8V, and the battery measures 16V, the relay drop-out is 2.8V (18.8V – 16V). Increase the module’s output voltage to 1-2V higher and repeat the process a few times to establish an average dropout voltage for your relay. Now you can set the module voltage to the fully charged battery voltage plus the relay drop-out voltage and start charging. Various globes in parallel with the relay coil can be used to set the charge current. I found that a Dolphin torch globe (not the LED type) gave 0.3A, a 12V 5W car wedge lamp gave about 0.5A and an old radio panel globe gave about 0.1A. Select a globe to suit by experimenting. The resistance temperature coefficient of your globe will give a charge current that only varies a small amount and will have just a small effect on your relay drop-out voltage. Don’t forget to record your relay dropout voltage for future use. Victor Duffey, Rosanna, Vic. ($75) I built my prototype on a small piece of protoboard, with some pins that attach it to the boost module. 96 Silicon Chip Australia's electronics magazine siliconchip.com.au 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. 05/26 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 ATmega328P ATtiny45-20PU ATtiny85-20PU PIC12F617-I/P 110dB RF Attenuator (Jul22), Basic RF Signal Generator (Jun23) 2m VHF CW/FM Test Generator (Oct23) Graphing Thermometer (Mar26), Simple LC Meter (May26) 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 Multi Logger (Feb21), USB-C Serial Adaptor (Jun24) 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 K-Type Thermostat (Nov23), Secure Remote Switch (RX, Dec23) Mains Power-Up Sequencer (Feb24 | repurposed firmware Jul24) 8CH Learning IR Remote (Oct24), Heat Transfer Controller (Aug25) Vacuum Controller (Oct25) 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) 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) PIC16LF15323-I/SL Remote Mains Switch (TX, Jul22), Secure Remote Switch (TX, Dec23) 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) 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 VARIOUS MODULES & PARTS - 0.96in 128x64 OLED screen with SSD1306 (PicoSDR, Apr26; SC6176) - 3.5in LCD module with ILI9488 controller (PicoSDR, Apr26; SC5062) - 0.91in 128x32 I2C OLED module (Simple LC Meter, May26; SC7484) μDCC DECODER KIT (SC7617) $10.00 $10.00 $7.50 (MAY 26) 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) SIMPLE LC METER COMPLETE KIT (SC7657) (MAY 26) POWER AMPLIFIER CLIPPING INDICATOR (SC7649) (MAY 26) Includes all the parts and the 3D-printed enclosure (see p67, May26) $25.00 $45.00 siliconchip.com.au/Shop/ DCC DECODER KIT (SC7524) (DEC 25) EARTH RADIO KIT (SC7582) (DEC 25) RP2350B COMPUTER (NOV 25) Includes everything in the parts list (see p73, Dec25) Includes everything to build the radio itself except the case and battery, plus the plug for the antenna (see p65, Dec25) $55.00 Assembled Board: a fully-assembled PCB with all non-optional components, front and rear panels are sold separately below (SC7531; see p28, Nov25) - front & rear panels (SC7532) - 8MiB APS6404L-3SQR-SN PSRAM SOIC-8 IC (SC7530) 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 PICKIT BASIC POWER BREAKOUT KIT (SC7512) (SEP 25) STEPPER MOTOR DRIVER KIT (SC7601) (APR 26) RP2350B DEVELOPMENT BOARD (AUG 25) $35.00 CALLIOPE AMPLIFIER PARTS (SC6021) (APR 26) Assembled Board: a pre-assembled PCB with all mandatory parts fitted, optional components are sold separately below (SC7514; see p49, Aug25) - 40-pin header (two are required, SC3189) $15.00 MIC THE MOUSE KIT (SC7508) (AUG 25) DCC BOOSTER / REVERSE LOOP CONTROLLER KIT (SC7579) (MAR 26) USB-C POWER MONITOR KIT (SC7489) (AUG 25) 433MHz RECEIVER KIT (SC7447) (JUN 25) VERSATILE BATTERY CHECKER KIT (SC7465) (MAY 25) Includes all required parts for DCC or DC mode (see p55, Apr26) Includes some of the harder-to-get transistors, resistors and a capacitor Includes all required parts, except for the Jiffy box, OLED screen (see below), power supply and front panel (see p58, Mar26) - 0.91-inch OLED screen (SC7484) DCC REMOTE CONTROLLER KIT (SC7552) $45.00 $7.50 (FEB 26) Includes all required parts, except for the case and wire/cable (see p63, Feb26) $35.00 Includes all parts except the jumper wire and glue (see p39, Sep25) Includes all parts except a CR2032 cell (see p64, Aug25) Includes all non-optional parts except the case, cell & glue (see p39, Aug25) Includes the PCB and all onboard parts (see p66, Jun25) MAINS HUM NOTCH FILTER (SC7598) (FEB 26) DCC BASE STATION KIT (SC7539) (JAN 26) RGB LED ‘ANALOG’ CLOCK KIT (SC7416) (MAY 25) RGB LED STAR KIT (SC7535) (DEC 25) USB POWER ADAPTOR COMPLETE KIT (SC7433) (MAY 25) Includes everything except for the case and power supply (see p53, Feb26) $50.00 Includes everything but the plastic case, power supply and some optional parts. The Pico 2 is supplied but not programmed (see p39, Jan26) $90.00 Includes the mostly-assembled board and all non-optional components except the power supply (see p43, Dec25) $80.00 $25.00 Includes everything in the parts list (including the case), except the optional components, batteries and glue (see p30, May25) $90.00 $7.50 $5.00 $20.00 $30.00 $1.00ea $37.50 $60.00 $20.00 $65.00 Includes all the parts except the power supply. When buying the kit select either a BZ-121 GPS module or Pico W (unprogrammed) for the time source (see p66, May25) $65.00 Includes everything in the parts list and a choice of one USB socket: USB-C power only; USB-C power+data; Type-B mini; or Type-B micro (see p80, May25) $10.00 *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. SERVICEMAN’S LOG Turning a pile of junk into computers Bruce Pierson of Dundathu, Queensland, repairs many laptop/notebook computers. He often gets them inexpensively (or even for free) because they’re broken, then uses parts from one to fix another. Here are several stories of computers he’s fixed lately... I have a few old laptops that I have installed various versions of Linux on to try out. Among these is a Compaq CQ60 that was my younger daughter’s first laptop. The last time I looked at it, it had a stuck key, causing it to beep continuously while on. Fixing that would require replacing the keyboard. I got it out recently and looked through my box of keyboards that I had salvaged from old laptops over time. I still did not have a keyboard that would suit this laptop and was reluctant to spend $25 to buy a new one for a device I’m not using. I then noticed that one corner of the keyboard surround near the screen was sticking up. I checked under the laptop and the screw was in place, so something must have broken inside. I removed the screws on the bottom that held the keyboard surround on and found that the brass nut had broken out of the post in the corner that was sticking up. I considered how I could repair this part. I decided to get out my 40W soldering iron to heat the brass nut and press it into the now shorter post. That worked, and I put the screw in to make sure it sat vertically. A bit more heat allowed me to true it up. Now I would need a longer screw for this corner. I looked through my laptop screws but I had nothing longer than the original screw. Then I remembered that several years ago, someone had given me a small parts cabinet with around 30 small drawers 98 Silicon Chip in it. I looked through the drawers; most of the parts were for PCs, but I found some laptop screws. They were mainly short, but in another drawer, I found one that was exactly the right length. I refitted the keyboard surround, but when I went to use the replacement screw, I discovered that the head was a larger diameter and it would not fit in the hole. So I put the screw in my small electric drill and, with the drill running, I used a file to reduce the diameter of the head, checking it periodically against the original screw to get the diameter approximately the same. With the screw modified, I was able to install it and now the keyboard surround is fitting correctly. Now I just need a good keyboard to get it back in working order. Toshiba C50D-A screen replacement Recently, a friend asked me if I could have a look at his Toshiba laptop. It had a round ‘black hole’ in the screen that was becoming increasingly annoying. The laptop was fine apart from this. I have seen some weird things with faulty screens in the past, but this is the first time I’ve seen one with a black hole. The cost of a new screen was over $90, so he wondered if I might have a good screen from an old laptop that would fit his. As it happened, I had recently disassembled a Toshiba L650 laptop that no longer worked, and I still had the shell and screen sitting on a shelf. I did some online research and found that both laptops use exactly the same screen. I started by removing the battery, then the RAM and HDD cover, and I took out the hard drive and RAM. Then I removed the optical drive plus the 15 screws securing the back shell, allowing me to remove the back shell. Australia's electronics magazine siliconchip.com.au Items Covered This Month • A tale of four computers • Repairing a Hisense 65U8G power board • A faulty IR sensor in a carport Dave Thompson runs PC Anytime in Christchurch, NZ. Website: www.pcanytime.co.nz Email: dave<at>pcanytime.co.nz Cartoonist – Louis Decrevel Website: loueee.com This laptop is very unusual in that the bottom shell comes off, leaving the motherboard in the top panel, whereas with most laptops, the top panel comes off, leaving the motherboard in the bottom shell. I could see that I would need to remove the motherboard to detach the cable going to the screen. This meant removing the keyboard. That turned out to be a nightmare with the way the keyboard is fitted into the top panel, but I finally got it out and unplugged the cable. Next, I removed the CPU fan and I was surprised by the amount of junk that was almost entirely blocking the fins on the heatsink. It’s a wonder the laptop had not been overheating; it was one of the worst I’ve seen. I unplugged all the plugs in various locations around the motherboard, then removed the single screw from the motherboard and lifted it up to unplug the video cable. After removing the motherboard, I cleared the rubbish off the heatsink and cleaned the small amount of dust off the fan. After removing the last two screws from each of the hinges, I had the lid with the screen free. Removing the two screws in the bottom front corners of the screen allowed me to prise the inner surround free from the lid. Then I noticed a problem. On one lower corner of the lid, the two small brass nuts had come out due to the old plastic becoming brittle over time and breaking. There was no easy way to remedy this situation. There would be no way to secure the hinge on that side to the lid without coming up with a solution. I did not have a spare lid for this laptop. My friend asked me what I could do to get the repair completed, as this laptop was very useful to him. I said I could put two screws through the lid from the back to secure the hinge, but that he would see the screws in the back of the lid. He said that he wasn’t concerned how the lid looked from the back. So I got the screen from the L650, unplugged the cable from it and removed the hinges. Then I did the same with the original screen and I fitted the original hinges and original cable to the replacement screen. With the screen re-fitted to the lid, I lined things up, drilled the two holes through the lid and then lightly countersunk them on the outside of the lid. I had to find two small screws and nuts that were long enough to do the job. This is not easy, as laptop screws do not commonly come that long. But with some searching through my containers of laptop screws, I found two suitable ones. I used the two small brass nuts that had come loose from the lid to fit the screws in the lid. This ensured that the hinges were in the correct place. I eventually found two tiny nuts to finish the repair. I fitted one to the screw through the hinge, then I replaced the surround and screwed the last nut onto the screw in the corner of the screen. The very dirty Toshiba C50D. siliconchip.com.au Australia's electronics magazine May 2026  99 I could now reassemble the laptop. I fitted the two screws to each hinge to hold the lid onto the laptop, then I connected the screen cable to the motherboard and sat the motherboard back in place. I screwed in the single screw that holds it to the top panel. I connected the rest of the cables to the motherboard, then put the CPU fan in place and installed the two screws that hold it to the motherboard, and plugged in its cable. I sat the back shell in place so I could turn the laptop over and connect the keyboard. I plugged in the keyboard cable, then I had a lot of trouble getting the keyboard back in place. I have never had this much trouble removing and refitting a keyboard on any other laptop previously. But I got it correctly fitted in the end. I closed the lid, turned the laptop back over and screwed the back shell on. Then I fitted the hard drive, RAM and optical drive. I replaced the cover for the hard drive and RAM, and installed the battery. I tested the laptop and everything was good with it now. I gave the keyboard a quick clean. My friend was really happy to see his laptop nice and clean, no longer with a hole in the screen. While it may not have been a cosmetically perfect repair, at least it saved the laptop from being scrapped. HP 15 Notebook RAM upgrade I wanted to try Windows 11 so, using a Windows 10 laptop, I downloaded the Windows 11 25H2 ISO file and used Rufus to copy it to a 16GB flash drive. I had an unused HP laptop but it won’t boot from a flash drive, like many later PCs will, so I had to run the setup from inside Windows 10. This laptop had no personal information on it, so I just wiped everything and started fresh with Windows 11. The installation went smoothly until I got to connecting to the internet. I knew that if I connected to the internet, that I would have to log in with a Microsoft account, which I did not want to do, as it would be a massive inconvenience to need internet access every time I wanted to log into Windows. I got to a command prompt by holding Shift and pressing F10, and I entered the command “oobe\bypassnro”. This initiated a reboot, and it then showed “I don’t have internet”, so I could log in with a local account, just like in Windows 10. At the Windows 11 desktop, the first thing I noticed was that the start button was in the middle of the taskbar, which was impractical. I found the setting and changed it back to where it should be. Then I found that many of the usual features were missing from the taskbar. I did some searching online and I found a way to fix this. I found Explorer Patcher and tried to download it using Microsoft Edge, but it would not complete the download, stopping before it was completed. So I downloaded and installed Google Chrome and then I was able to download Explorer Patcher and run it. That fixed the taskbar and I was then able to put Quick Launch back on it. This HP laptop only had 4GB of RAM, which is very low for Windows 11. I wanted to upgrade the RAM to 8GB. This HP laptop is one of those laptops that must be completely dismantled to replace the RAM or change the hard drive, which makes upgrading or changing anything difficult. With the top panel removed, I had to remove the motherboard to find the RAM. At this point, I was becoming concerned that the RAM might be soldered to the motherboard and not be upgradeable, as I’ve found this on some laptops previously. But after removing the motherboard, I found that there was a single 4GB RAM module in a slot, so it could be upgraded, unlike the soldered CPU. Now I needed an 8GB RAM module. I still had several old, non-working laptops, so I started by checking all the The HP 15 motherboard; the RAM is next to the CMOS cell. 100 Silicon Chip Australia's electronics magazine siliconchip.com.au HP laptops, but I did not find any 8GB RAM modules. Then I also checked other brands of non-working laptops and I removed several hard drives and RAM modules, but I still had no 8GB RAM module. Then I found an Asus F553M laptop that was another one of these laptops that needs to be completely dismantled to access anything. I dismantled it and it had one 8GB RAM module. I got my Dell laptop that has Linux on it and I removed the two 4GB RAM modules and installed the single 8GB RAM module. Running MemTest86+, it went through the entire test with no errors, so I knew that I had a good 8GB RAM module. I then installed the 8GB RAM module in the HP laptop. Next, I decided to check the CR2032 cell to see what condition it was in. I first tested it with my multimeter and it read 2.97V, a sure indication that it had reached the end of its life. I got out my dedicated cell and battery tester and checked the cell and it read 1V, 0%, so it needed to be replaced. The new cell measured 3.2V and 100%, so I fitted it to the laptop motherboard. It’s always a good idea to test replacement cells to make sure they are still good, as some cells may be getting old and losing their voltage, which happens over time, even when a cell is not being used. Some laptops have the CMOS battery (cell) located in a convenient location under one of the covers, usually the RAM cover. But a lot of laptops have it in a location that is not visible, and it’s necessary to dismantle the laptop in order to replace the cell. Some laptops even have the cell soldered to the motherboard, but these are mostly rechargeable cells and they don’t normally need replacing for the life of the laptop. With the laptop reassembled, I could see that the battery had started charging after sitting on 0% for some time while I had been using it. Laptop batteries that have been sitting around for a long time will usually go flat. Often they will not charge up again, but in some cases they will come good if left on charge for a long time. I ran msinfo32, which brought up the specifications for the laptop. This is a very handy command for finding out just what’s inside a laptop, as it shows the CPU, hard drive, RAM and many other details. Compaq CQ42 CPU upgrade I was setting up a Compaq CQ42 to run Linux when I found that the CMOS battery (cell) was flat. It would be a big job to change the cell, as the laptop would need to be completely dismantled and the motherboard removed to access the cell. Unfortunately, this is another of that frustrating class of portable computers that has the CMOS cell mounted in an inaccessible place. So once again, I’d have to totally dismantle it to complete the swap. Seeing that I would have to go a lot of trouble just to replace the cell, I thought I would upgrade the CPU while I had it apart. It had a Celeron T3100 at 1.90GHz; I had some spare CPUs that I’d salvaged from dead and defective laptops. I started by searching through the CPUs that had the same socket (PGA478). I set aside any processor that was faster than 2GHz – I had four. Next, I checked which CPUs were compatible with the CQ42 motherboard. I found the siliconchip.com.au Australia's electronics magazine May 2026  101 I figured that while replacing the CR2032 cell in this Compaq CQ42 laptop, I could also replace the CPU, best option to be a Pentium dual-core P4500 at 2.3GHz, as it was listed as the most common CPU in the CQ42. I had a faster 2.4GHz CPU but it was not compatible. The first step was to remove the battery and the cover for the hard drive, then the cover for the RAM. Next, I removed the optical drive. I first opened it with an optical drive eject tool so that I could pull on the tray and not the front panel. Then I removed the WiFi card after removing the mounting screw and unplugging the two wires. Next, I removed the three screws holding in the hard drive and unplugged the connector. Most hard drives are not held in with screws like this one. Many laptop keyboards are held in with small clips at the top or bottom of the keyboard, or occasionally screws at the top of the keyboard that are accessible after removing a panel. The CQ42 is quite different in that the keyboard is held in by six screws from the underside. I removed the six screws and then used the optical drive eject tool to push up on the keyboard through one of the screw holes. This allowed me to lift up the keyboard, disconnect the cable and lift the keyboard clear. I then removed the remaining screws on the bottom of the laptop and the one screw under the keyboard, unplugged the four cables and prised the top panel off. 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. 102 Silicon Chip After removing one screw holding in the CPU cooling fan and two holding in the motherboard, I unplugged all the cables and lifted out the motherboard. I could then unscrew the six screws holding the heatsink and fan to it and remove the heatsink with the fan still attached to it. Then I cleaned the old heatsink compound off the CPU heatsink. I fired up the compressor and blew compressed air through the fins of the heatsink. Quite a lot of junk came out, so it was definitely in need of cleaning. I also cleaned the fan’s fins with a damp, squashed cotton bud so that the assembly would be ready to refit after changing the CPU. I changed the CPU, applied new heatsink compound and reinstalled the heatsink. Then I changed the CMOS battery (cell), which was the main reason for completely dismantling the laptop. With that done, it was time to reassemble it. I put the motherboard back in the bottom shell and installed the two screws to hold it in and the one screw to hold in the CPU cooling fan. Next, I reconnected all the cables, put the top panel back in place and connected the four cables that were in the top shell. I installed the one screw in the top shell and all the screws in the bottom shell. I then plugged in the keyboard cable, put the keyboard in place and reinstalled the six screws from the bottom. After reinstalling the WiFi card and connecting its two wires, I refitted the optical drive and installed the screw that holds it in place. Then I plugged in the hard drive connector, sat the hard drive in place and drove in the three screws. I put the hard drive cover on, installed one 2GB RAM module and put the battery back in. The battery was not charged, so I connected a charger and pressed the power button. I tapped the Esc key and then I pressed the F10 key to access the BIOS setup. I set the time and date, then checked the other settings before exiting setup and saving the new settings. Now that I was ready to install the operating system, I switched it off, inserted the other 2GB RAM module and Australia's electronics magazine siliconchip.com.au put the RAM cover back on. I considered upgrading the RAM to 8GB, but I decided not to, as Linux is pretty light on RAM usage and I would only be using it for web surfing and research. I had already set the laptop to boot from the optical drive as the first choice, so I booted from the PearOS Monterey installation DVD. Installing Linux on these old laptops gives them a new lease on life. It can fit on a 40GB hard drive, but I usually use 120GB or larger. Hisense 65U8G power board repair This LCD TV has a dimmable LED backlight, using more power than a normal LCD TV with a simple backlight. The advantage is higher contrast (stronger blacks). An LCD panel does not fully block the backlight, so the blacks appear dark grey. By selectively switching off the backlight elements, the blacks are more black. In the future, RGB panels, with a matrix of red, blue, and green LEDs, promise to provide a high-contrast screen better than OLED TVs. The power board in this TV has a power factor correction (PFC) stage using an IPD2308 IC that makes its current draw more sinusoidal, in phase with the mains voltage waveform. The normal capacitor input supplies used in LCD TVs take large spikes of current at the peak of the mains voltage and are not popular with supply companies. This PFC circuit is unusual in that it uses two transformers, each driven by a separate input Mosfet, although both Mosfets are driven by the same IDP2308 chip. I think this is done because it’s easier to fit two smaller transformers than one large one. The outputs of the two transformers are connected so that only one Mosfet half-bridge is required on the output side. The power fuse to the board was blown, and both the input Mosfets were shorted. The input Mosfets share the same 0.05W current-sensing resistor (3 × 0.15W in parallel). These were blown open. The circuits driving the input Mosfets were damaged as the Mosfets shorted, and the IPD2308 was also destroyed. Each Mosfet had a PNP emitter-follower transistor to speed up its switch-off. Surprisingly, the PNP transistors survived, but two resistors in each driving circuit were open-circuit. So quite a few components to replace. As the IC and resistors are surface mount, you need a hot air gun for the IC and hot tweezers for the resistors. So you have to decide whether to repair or buy a second-hand board on eBay or similar. Roger Sanderson, Sinnamon Park, Qld. IR motion sensor repair We have a sensor in our carport looking at the driveway to detect visitors as they enter the property. This is necessary as the driveway is not easily seen from inside the house. The sensor is a simple infrared motion detector (transmitter) with a separate light/beeper box (receiver) to provide an indication of activity in the driveway. The units are connected wirelessly and run off batteries that seem to last forever. I bought the unit from Altronics, and it has proved reliable and just the right solution for the job. After many years of flawless service, the unit developed siliconchip.com.au an intermittent fault. The lights in the receiver would flash when triggered, but the audible alarm would not sound. As the beeper unit normally sits on the hall table where it can’t be readily seen, this was a problem. I assumed the transmitter unit was working correctly. I duly inspected the receiver unit, replaced the batteries, and the beeper came back to life. Good! The unit was put back into service and continued its duties until the beeper failed again several months later. This time, I took the back off the receiver and gave it a thorough inspection. It was a fairly simple construction, a main printed circuit board with a small wireless receiver board soldered to its side. Nothing was obviously amiss. I touched up a few possibly cold solder joints, but still no sound. Checking the loudspeaker, I found it was fine, measuring 95W and producing a healthy click each time the meter probes were attached. I removed a transistor that seemed to switch the input to the audio circuits and tested it, but it was reported as working correctly, so I returned it to the circuit. Various other components were checked in-circuit with nothing obvious showing up. Fortunately, most of the components were marked with their values, and that allowed easy checking. As I worked through these components, it came to the point where a small IC on the board was the only untested component in the beeper circuit. I could not figure out what it actually did; it had an obscure part number that failed to show up in web searches. At that point, I decided it was time to give up and look for a replacement driveway detector. After much looking around at various modern equivalents that had up to 50 tones, pushbuttons galore, connecting to my phone and everything else I did not want, I found Altronics were still selling the original unit and duly ordered a new one. While waiting for the new unit, I could not leave the thought alone that it was a simple unit, the fault had to be in the beeper circuitry, and I could not allow myself to be defeated! So instead of tidying up my bench and sweeping the faulty unit into the bin, I had another look. Having eliminated all the likely components around the beeper circuit, I realised that the beeper had two sound levels that were controlled by a two-pole, three-position slide switch located on the other side of the board. The switch doubled as the on/off switch and was connected to the beeper circuit by two tracks that meandered across the board, avoiding other tracks and components. Testing the switch contacts, I quickly found that they were either open-circuit or had a high resistance. I bridged out the switch, and the beeper came to life! I decided that as we only ever used the unit on low volume, it was easier to leave the switch bridged than find a replacement. The on/off side of the switch seemed to be working fine. With 20/20 hindsight, I realised that in circuits such as these where there is little loading of parts, and barring a random component failure, the most likely component to fail is the one subject to mechanical wear. So I probably should have looked at the switch first. The unit was returned to service, and I now have a brand new unit sitting on my shelf as a backup! SC Nigel Dudley, Ocean Beach, WA. Australia's electronics magazine May 2026  103 Vintage Radio Airzone 6552A Concert Star from 1947 This Australian post-war set is based on a design from 1941. The circuit is a conventional superhet design; its appeal lies mainly in the flamboyant cabinet styling, reminiscent of a concert hall. By Assoc. Prof. Graham Parslow T he almost-identical Airzone 6651A was first offered for sale in 1941 but the government stopped all domestic radio production when components were reserved for war manufacture. A contemporary advert read: Airzone have presented another star to join their constellation. It is a new brighter and better star in the mantel world – the sparkling Concert Star. Buy the best mantel in Australia for £17/10/-. The model 6552A was almost the same radio when it was released in 1946, although the retail price had increased to £20/12/6. The styling was comparable to other late-1930s Bakelite radios and it used heritage circuitry. The speaker in this radio is stamped September 1947; it is unclear whether this electromagnet field coil speaker would have been made in 1947 or pulled from shelves that had been storing components during the war. In 1947, Rola were making excellent permanent-magnet speakers that were a better choice unless old stock needed to be used. A friend acquired this radio and passed it onto me for checking and restoration. A quick glance was enough to 104 Silicon Chip confirm that it was not a quick plugin-and-return task. It never ceases to amaze what debris ends up inside old radios. In this case it was chicken bones! The dirtier the chassis at the start of a restoration, the greater the satisfaction with seeing a resplendent end product. This one was certainly dirty. My standard procedure is to remove all the valves first. For very dirty radios like this one, the next step is a blow-off with compressed air. Turpentine and a brush can then remove or loosen a lot of the surface accumulations. Then comes a final compressed air blow-off. The Airzone factory that used to be on Paramatta road. Australia's electronics magazine Extensive light surface rust on this chassis was covered with chrome paint. The transformer and valve shields were repainted. This was adequate to satisfy me that the result would be gratefully appreciated when it was returned. Ian Batty (another Vintage Radio author in Silicon Chip) informed me that perfection is the enemy of the good. In other words, a lot of time can be wasted in seeking perfection when something is adequate. A bit of Airzone history At age 30 in 1925, engineer Claude Plowman established a business fabricating components for crystal sets. This was two years after the introduction of public radio transmissions. He had judged the market well and learnt that delivering quality products was best done by manufacturing in-house. Plowman registered the trademark Airzone in 1926. The coils wound by Airzone stood out for excellence. There was continuous growth in the output from Airzone through the 1930s. Airzone produced some of the most collectable Australian radios from the 1930s, due to their beautiful designs and the quality of their timber and siliconchip.com.au Bakelite cabinets. The growth of Airzone was helped by wartime manufacture of instruments for radar testing, various communications items and making ASDIC (sonar) echo-location equipment. This led to opening a large factory at Paramatta Road in Sydney in 1944 (see the drawing opposite). Post-war, Airzone returned to domestic radio production and badge-engineered radios to be sold as Malvern Star, Mullard and Peal. Their success led to a company take-over by the large EMAIL (Electricity Meter & Allied Industries Ltd) group, although Claude Plowman remained as manager. The changes brought about from the takeover resulted in the termination of Airzone radio production in 1955. The Airzone legacy to collectable Australian radios is substantial. Circuit details The circuit has been scanned from page 25 of the Official Australian Radio Service Manual (OARSM) Volume 5, 1946. The valve lineup (6A8G, 6U7G, 6B6G, 6F6G and 5Y3) is a classic prewar superheterodyne arrangement, widely used in Australian mantel radios of the late 1930s and early 1940s. By the time this set reached the market post-war, the design was already conservative but well proven, offering reliable performance rather than innovation. R1 (10kW) is connected in parallel with the primary antenna coil. Per Roger Johnson (Electronics Australia, November 1998, p62), this broadens the tuning of the antenna circuit by lowering the secondary Q by damping the primary winding. Without the detuning lower frequency stations are emphasised over higher frequency stations. After this, the switching between MW and SW is relatively simple. The tuning is accomplished by conventional ganged variable capacitors. There is a switch linked to the band change mechanism, between two sets of dial lamps, that could be used to switch the lamps. However, on this radio, the four dial lamps remain on regardless of band selection. The representation of the 6A8 mixer valve uses an old convention of drawing crinkled electrodes much like a resistor. All of the electrodes are drawn stacked between the cathode siliconchip.com.au The top two photos show the rear of the cabinet and the chassis in their unrestored and very dusty condition. The bottom photo of the chassis is what it looked like after a good clean. Australia's electronics magazine May 2026  105 This is what the underside of the chassis looked like before any work was done. and anode, rather than set apart as a pentode and triode. The 6A8 was released in 1935 and is relatively common in pre-war radios. Two separate local oscillator coils pass a mixing frequency to the 6A8 via capacitor C2. The result is an intermediate frequency (IF) output at 456kHz. The 6U7 IF amplifier is a pentode, although it is drawn as a tetrode. The omitted electrode is connected internally to the cathode. AGC is applied to both the 6A8 and 6U7 via 1MW resistor R7, which connects to the detector diodes in the 6B6. A second IF transformer passes the signal to the detector diodes. Audio from the diodes passes to the volume control potentiometer, R12; the slider is connected directly to the top-cap grid of the 6B6. The negative voltage from the diodes is prevented from reaching the 6B6 grid by 10nF capacitor C11. The 6F6 output pentode is another venerable valve from 1935. It is drawn here as if it were only a tetrode. This valve needs a relatively high grid bias voltage to minimise distortion. A grid bias of -13V is specified in the circuit diagram. The 460W wirewound cathode resistor, R16, delivers that bias (measured as -10.7V in this radio). The 6F6 grid is held at Earth potential by resistor R15 (5MW), a resistor that is more commonly encountered as 500kW. C13, the 10nF audio coupling capacitor, needs to be leakage-free to prevent voltage from the 6B6 anode from driving the 6F6G grid positive. The use of a 5Y3 full-wave rectifier is another link to heritage parts. The 5Y3 is the old type 80 valve with four pins, repackaged into an octal base. It is an excellent rectifier, but has two drawbacks. First, the cathode is directly heated, so almost immediately from switch-on, the 5Y3 is generating a The recabled speaker and restored chassis are shown here. Note the replaced mains lead. 106 Silicon Chip higher voltage than the eventual voltage under load when the other valves have warmed up. This can stress components in the HT line, causing failure. The other downside is the need for a separate 5V AC transformer winding, increasing the cost of the transformer. At the time, a range of indirectly heated rectifier valves such as the 6V4 were available. 1947 was close to the end of the period when octal-base valves were used in radios, because new miniature 7-pin and 9-pin valves were becoming available. Due to large inventories and war surplus, octal valves continued to appear in radios well into the mid-1950s. Radio service people often had substantial numbers of spare valves. Such new-old-stock and salvaged valves have generated a valve bank of approximately 70,000 held for the use of members of the Historical Radio Society of Australia (see hrsa.org.au). Electrical restoration The two-core mains lead was replaced with a newly-manufactured cloth-covered three-core cable. That original old two-core cable was commonly also used for light fittings. The expense of using specially-made new cable is readily justified by keeping the external appearance of the radio true to period. More importantly, adding an Earth wire can both improve performance and enhance safety. Additionally, the dial cord was replaced and new dial lamps installed. The speaker cable was unserviceable and was rewired with coloured wire reclaimed from old switch-mode computer power supplies. The old computer wire is handy for medium-­ current applications and colour tracking separate lines. Under the chassis The first power-up was with without valves and the four globes illuminated with a stable power draw of 15W. 8W of this was just the globes. Sometimes all capacitors remain serviceable, and I had a good feeling about this radio. Accordingly, without the mains connected, I connected a bench HT supply ramped it up to 250V DC, allowing the electrolytics to re-form. In the end, it only drew 2mA at 250V. This tested all the paper capacitors subjected to high voltage with one important exception: C13, the audio coupling capacitor, which I replaced before a full power-up. With the valves installed and power applied, only two strong stations were received very faintly. A signal tracer showed good signal input from multiple stations was delivered to the volume pot. The wiper on the pot was broken and made no connection. After replacing the pot, the radio worked properly again, drawing 52W from the mains. At raised volume, the speaker was poling and distorting. Luckily, this was easily fixed by re-gluing the cone to the rim where it had separated. Restoring the cabinet The chief detraction from the cabinet was the soiled grille cloth. The cloth was folded into the theatre-­ curtain pattern that was in vogue in the late 1940s (recall that this radio is called the Concert Star). I took a gamble that worked in this case. I sprayed automotive degreaser onto the cloth and brushed it in. Copious water cleansing followed, to remove the degreaser, and the result was an impressively clean grille cloth unharmed by the harsh treatment. The case suffered from the kitchen ceiling disease, which is contracted when a ceiling is roller-painted without adequate protection to what is below. It has a light covering on the face, but a much heavier spatter was over the top. The globs of white paint were removed by careful rubbing with grade zero steel wool soaked with carnauba wax (car polish). This had the twin benefit of cleaning and polishing the SC cabinet. Fig.1: the circuit for the Airzone 6552A radio with the components labelled for convenience. siliconchip.com.au Australia's electronics magazine May 2026  107 PRINTED CIRCUIT BOARDS & CASE PIECES PRINTED CIRCUIT BOARD TO SUIT PROJECT SALAD BOWL SPEAKER CROSSOVER PIC PROGRAMMING ADAPTOR 2M VHF CW/FM TEST GENERATOR TQFP-32 PROGRAMMING ADAPTOR ↳ TQFP-44 ↳ TQFP-48 ↳ TQFP-64 K-TYPE THERMOMETER / THERMOSTAT (SET; RED) MODEM / ROUTER WATCHDOG (BLUE) DISCRETE MICROAMP LED FLASHER MAGNETIC LEVITATION DEMONSTRATION MULTI-CHANNEL VOLUME CONTROL: VOLUME PCB ↳ CONTROL PCB ↳ OLED PCB SECURE REMOTE SWITCH RECEIVER ↳ TRANSMITTER (MODULE VERSION) ↳ TRANSMITTER (DISCRETE VERSION COIN CELL EMULATOR (BLACK) IDEAL BRIDGE RECTIFIER, 28mm SQUARE SPADE ↳ 21mm SQUARE PIN ↳ 5mm PITCH SIL ↳ MINI SOT-23 ↳ STANDALONE D2PAK SMD ↳ STANDALONE TO-220 (70μm COPPER) RASPBERRY PI CLOCK RADIO MAIN PCB ↳ DISPLAY PCB KEYBOARD ADAPTOR (VGA PICOMITE) ↳ PS2X2PICO VERSION MICROPHONE PREAMPLIFIER ↳ EMBEDDED VERSION RAILWAY POINTS CONTROLLER TRANSMITTER ↳ RECEIVER LASER COMMUNICATOR TRANSMITTER ↳ RECEIVER PICO DIGITAL VIDEO TERMINAL ↳ FRONT PANEL FOR ALTRONICS H0190 (BLACK) ↳ FRONT PANEL FOR ALTRONICS H0191 (BLACK) ARDUINO FOR ARDUINIANS (PACK OF SIX PCBS) ↳ PROJECT 27 PCB WII NUNCHUK RGB LIGHT DRIVER (BLACK) 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) DATE SEP23 SEP23 OCT23 OCT23 OCT23 OCT23 OCT23 NOV23 NOV23 NOV23 NOV23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 DEC23 JAN24 JAN24 JAN24 JAN24 FEB24 FEB24 FEB24 FEB24 MAR24 MAR24 MAR24 MAR24 MAR24 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 PCB CODE 01109231 24105231 06107231 24108231 24108232 24108233 24108234 04108231/2 10111231 SC6868 SC6866 01111221 01111222 01111223 10109231 10109232 10109233 18101231 18101241 18101242 18101243 18101244 18101245 18101246 19101241 19101242 07111231 07111232 01110231 01110232 09101241 09101242 16102241 16102242 07112231 07112232 07112233 SC6903 SC6904 16103241 08101241 08104241 07102241 04104241 04112231 10104241 SC6963 08106241 08106242 08106243 24106241 CSE240203A CSE240204A 11104241 23106241 23106242 08103241 08103242 23109241 23109242 23109243 23109244 19101231 04109241 18108241 18108242 07106241 07101222 15108241 28110241 18109241 11111241 08107241/2 Price $10.00 $5.00 $5.00 $5.00 $5.00 $5.00 $5.00 $10.00 $2.50 $2.50 $5.00 $5.00 $5.00 $3.00 $5.00 $2.50 $2.50 $5.00 $2.00 $2.00 $2.00 $1.00 $3.00 $5.00 $12.50 $7.50 $2.50 $2.50 $7.50 $7.50 $5.00 $2.50 $5.00 $2.50 $5.00 $2.50 $2.50 $20.00 $7.50 $20.00 $15.00 $10.00 $5.00 $10.00 $2.50 $5.00 $10.00 $2.50 $2.50 $2.50 $2.50 $5.00 $5.00 $15.00 $10.00 $12.50 $2.50 $2.50 $10.00 $10.00 $10.00 $5.00 $5.00 $7.50 $5.00 $2.50 $2.50 $2.50 $7.50 $7.50 $5.00 $15.00 $5.00 For a complete list, go to siliconchip.com.au/Shop/8 PRINTED CIRCUIT BOARD TO SUIT PROJECT 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) 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 DATE 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 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 PCB CODE Price 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 SC7527 $7.50 15104251 $3.50 18106251 $2.00 09110245 $3.00 01107251 $30.00 01107252 $2.50 01107253 $7.50 10109251 $10.00 10109252 $2.50 P9058-1-C $5.00 16112251 $12.50 06110251 $5.00 09111241 $2.50 09111243 $5.00 09111244 $5.00 01106251 $5.00 01106252 $2.50 09111245 $5.00 01003261 $7.50 10111251 $2.50 09111248 $5.00 09111249 $5.00 17112251 $7.50 04102261 $3.00 CSE251101 $5.00 CSE251102 $5.00 CSE251103 $7.50 09111242 $2.00 01111212 $5.00 01110251 $2.50 01110252 $5.00 μDCC DECODER SIMPLE LC METER WIFI ALARM MONITOR POWER AMPLIFIER CLIPPING INDICATOR MAY26 MAY26 MAY26 MAY26 09111247 04103261 01304261 01104261 NEW PCBs $1.50 $2.50 $2.50 $15.00 We also sell the Silicon Chip PDFs on USB, RTV&H USB, Vintage Radio USB and more at siliconchip.com.au/Shop/3 ASK SILICON CHIP Got a technical problem? Can’t understand a piece of jargon or some technical principle? Drop us a line and we’ll answer your question. Send your email to silicon<at>siliconchip.com.au Help building the Internet Radio The headline/article grabbed my attention (February & March 2026; siliconchip.au/Series/458), but on reading the article, reality struck. I don’t know anything about Raspberry Pis or 3D printing. Can you direct me to articles that can provide some background on the Raspberry Pi so I can consider building the radio? 3D printing might be another issue. Are there files that I might be able to persuade a mate to print for me? (R. P., Kingsvale, NSW) ● The designer, Phil Prosser, responds: the files to print the radio can be downloaded from siliconchip. au/Shop/6/3593 If you don’t have a 3D printer (they are available from Jaycar and Altronics), it would be a good idea to ask a friend for help. I suggest you talk to them and see if they are OK with running a long print job for you. I would also buy the filament for them as you really want to start with a couple of rolls of your chosen type and colour. We used PLA filament, which is cheap and easy to print with. On setting up the Raspberry Pi, I suggest you follow the instructions in the article to get the Pi booted and running with a normal computer monitor, keyboard and mouse. At that point, I think you will be surprised at how familiar it is. If you have a question, Google is your friend. Raspbian (and Linux in general) has a massive support base, so typing a straightforward question into Google leads to very clear advice. I am a very infrequent Linux user, so I did exactly that myself. As a result of the strong support for Linux, which is what the Raspbian environment really is, there is a stunning range of free applications and tools ready to download. These are not dinky copies of what you might seek; you can get properly supported mainstream tools for pretty well anything you choose to do. siliconchip.com.au So, short of giving you a list of sites, I suggest you get a Pi 4 or 5 (they are about the same price but if you want to try Linux, the Pi 5 is better – note the absence of onboard audio, though) and get it running, I expect you will quickly realise the support for this is broad and accessible. Correct component placement is important! I purchased the USB-C Power Monitor short-form kit (SC7489; August & September 2025; siliconchip.au/ Series/445). After completing the assembly, I was unable to get the display to function. Initially, I thought that I had made some error in construction and examined all soldering joints, component placement, connections etc. After a detailed investigation, I found that the I2C and power signals for the PCB differed from the circuit diagram and source code for the board. The board and PCB artwork that I downloaded have the display VCC from pin 6, SCL from pin 5 and SDA from pin 4. The magazine circuit and the source code show VCC supplied from pin 16, SCL from pin 15 and SDA from pin 14. Monitoring the CPU pins, the firmware on the chip follows the circuit diagram, not the PCB layout. I’m not sure how many of these boards have been sold, but the CPU firmware I was supplied is not the correct version for the PCB. I have no facility to reprogram the microcontroller and there is a risk of melting the plastic cases of switches, the potentiometer and switches using Difficulty getting Ultrasonic Cleaner to resonance I built the High-Power Ultrasonic Cleaner from the September & October 2020 issues (siliconchip.au/Series/350). The unit works fine in troubleshooting mode, but it will not operate properly in ‘normal mode’. If I start normally by pressing START, the red LED goes off and the second green LED lights. Then LEDs 2 & 3 light, but it falls back to the second green light. It alternates between these two states. After a while, just the second green LED was lit steadily, and the red LED came on and stayed on. At that stage, TP1 = 1.46V, with a frequency of about 3MHz. If I then go to troubleshooting mode, all seems well, ie, all five green LEDs light, TP1 = 1.27V. By varying the pot, I can see the TP1 voltage vary and frequency vary, around about 40kHz, as expected. Adjusting the pot for a peak voltage, max TP1 = 2.10V at 39.0kHz. I know the TP1 voltage seems low compared to the expected 4V or so, but I already put 10 more turns on the transformer with only a small increase in the voltage at TP1. I am thinking of rewinding a new transformer, removing the cover and glued transducer from the tank to make sure the transducer is hard up against the tank, and maybe positioning it under the tank. ● Sorry you are experiencing trouble with the Ultrasonic cleaner. Regarding the operating frequency, it seems that the transducer resonance can’t be found. The cleaner won’t operate correctly in that case. This could be because the number of windings on the transformer is not right for the transducer. We note that you added 10 turns to the transformer. This is probably too large a step, and you may have missed the resonance point with the change being so large. Perhaps unwind nine turns, then add one winding at a time, retesting each time. Use the diagnostic mode to find resonance, then try normal operation. Obtaining 4.2V at TP1 is important. If you are still unsure, please re-read the final section in the October 2020 article titled “Troubleshooting”. Australia's electronics magazine May 2026  109 Avoiding 5G interference with satellite TV The 5G network is causing a lot of interference with my satellite TV reception. Is it better to get an LNC on the feedhorn, or should I use a PLL LNB converter with a 5G filter built in? (J. E., via telephone) ● We asked Garry Cratt of Av-Comm Space & Defence and he responded: the 5G frequency allocation overlaps part of the internationally recognised C band (3.4-4.2GHz) in many parts of Australia. The typical satellite signal falling on Earth is in the fractions of a microvolt, and a 5G base station must transmit a few watts. The effect of such a strong signal in close physical proximity to a C-band satellite dish is to overload the LNB (LowNoise Block converter). The only solution to remedy this without physically moving the satellite dish out of the line-of-sight of the signal source is to filter out the 5G frequency before it is amplified by the LNB. Fortunately, in recent years, we have been able to manufacture LNBs with sufficient filtering to exclude the interference. Unfortunately, the cost of this kind of LNB means that is only being used by commercial operators (radio and TV stations etc). For private satellite enthusiasts, the only realistic solutions are relocating the dish or finding another source of the desired programming. hot air to rework the board. It shouldn’t be necessary to reverse engineer the PCB and modify the source code to get this project working. How can this situation be rectified? (H. K., Mount Evelyn, Vic) ● For VCC, SCL and SDA to be present on pins 6, 5 and 4 of IC1, it would have to be rotated 180° relative to the orientation shown in the Fig.6 PCB overlay diagram on page 80 of the September 2025 issue. Note the dot and ‘1’ marker showing that pin 1 is at bottom right. We are confident that if you carefully desolder IC1 and rotate it by 180°, then resolder it, the kit will work. An ideal bridge rectifier for power amplifiers I am inquiring whether the “Ideal Bridge Rectifier kit” is suitable for the SC200 Amplifier. If it is suitable, which version of the Ideal Bridge Rectifier kit should I be buying? (W. L., Singapore) ● We have two different sets of Ideal Bridge Rectifier kits, some based on the December 2023 Ideal Bridge Rectifier (siliconchip.au/Article/16043) and some on the September 2024 Discrete Ideal Bridge Rectifier (siliconchip.au/ Article/16580). You would need two of the December 2023 kits, as one can’t provide the split rails the amplifier requires. The SC6850, SC6851 and SC6852 kits can all operate up to 72V/10A. That should be sufficient in theory. Still, it would be better to use two of the SC6854 kits, rated at 72V/20A, to ensure it’s robust enough to handle the switch-on inrush current and such. They’re only slightly more expensive. You can see the information or purchase them at this link: siliconchip. au/Shop/20/6854 That kit uses large SMD transistors in D2PAK/TO-263 packages, which are not difficult to solder (although they require a fair bit of heat). They’re heatsinked by the board. We have a similar kit using through-hole TO-220 transistors, which is also rated at 20A, although it’s currently out of stock (code SC6855). We will be restocking it, but only in small quantities. Note that you also need a transformer with two separate secondaries, not one centre-tapped secondary, but that is how most high-power transformers are configured anyway. The September 2024 design is limited to ±40V, so it would be a good choice for a lower-power amplifier like the Hummingbird but would need modifications to work with the SC200. We’re considering whether it can be upgraded in future to handle at least ±60V, making it more suitable for use with high-power hifi audio amplifiers. isoundBar speaker driver alternatives I am interested in making a sound bar, but I have some problems with the August 2022 isoundBar (siliconchip. au/Article/15426). Two of the Vifa-Peerless drivers used are not available from Wagner Electronics, the original supplier. Can you suggest alternatives or another Australian source? Also, the width of the overall unit is too wide to fit between the feet of my TV, so I’d like to change the box dimensions to 1m wide from the original 1240mm. I will need to recalculate the size of each speaker section to retain the original volume, either sealed or vented. I won’t go to this trouble if no drivers are available/suitable. I have a spare 24V AC transformer, so I’d make a power supply for the 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. 110 Silicon Chip Australia's electronics magazine siliconchip.com.au MARKET CENTRE Advertise your product or services here in Silicon Chip KIT ASSEMBLY & REPAIR FOR SALE PCB PRODUCTION 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 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 KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith: 0409 662 794 keith.rippon<at>gmail.com LEDS, BRAND NAME AND GENERIC LEDs, filament LEDs, LED drivers, heatsinks, power supplies, kits and modules, components, breadboards, hardware, magnets. Please visit www. ledsales.com.au Silicon Chip Binders REAL VALUE AT $21.50 PLU S P&P PMD WAY offers (almost) everything for the electronics enthusiast – with full warranty, technical support and free delivery worldwide. Visit pmdway.com to get started. Order online from www.siliconchip.com.au/ Shop/4 or call (02) 9939 3295. 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. amplifier, but can I locate this inside the vacant area next to the amplifier board? (I. S., Glenhaven, NSW) ● Alternative drivers are available from Wagner Electronics but you will need to change a few dimensions to fit them. The critical TC6FD00-04s can be replaced with 2.5-inch Daichi midrange/woofers, Wagner Cat HFS6415-8. These are rated at 8W rather than 4W, meaning a higher supply voltage may be desirable, and they will need a larger diameter hole (55mm). They are slightly taller, needing a 70mm tall baffle (your proposed changes will accommodate this). For the tweeters, you could use Daytona 6W 20FA-6 3/4-inch Neodymium types, Cat ND20FA. The slightly higher impedance should not cause any problems. An alternative to the Vifa TG9FD1004 woofer is the Dayton PC83-4 3-inch siliconchip.com.au full-range 4W driver, also available from Wagner. This is slightly taller at 46.5mm and has a smaller diameter (78.5mm) so you will need to change the cut-out dimensions to fit it up. While these substitute drivers are similar, they will probably require different relative drive levels to the original set, but that’s easily accommodated by the suggested amplifier, which lets you adjust the levels individually by ear. Changing the isoundBar width to 1m is fine. As you’re reducing the width by 19.4%, increasing the internal height by 19.4%, from 64mm to 80mm, should keep the internal volumes similar. That will help you fit the slightly larger drivers too. You should also adjust the baffle positions proportionally, reducing the width of each internal chamber by roughly 20%. Australia's electronics magazine It’s OK to install the power supply in the box, but ensure adequate cooling and shielding, and make sure any mains wiring is properly insulated and the wire colours are correct. We purposefully avoided any mains voltages in the project to make it beginner-­ friendly. We hope this advice helps you. Connector pin order isn’t obvious Hi, I recently purchased the Pico BackPack Kit and during assembly, I determined that the PCB (07101221 RevC) differs from the circuit diagram in March 2022 (siliconchip.au/ Article/15236). The circuit diagram that I have shows jumper JP2 connected to pin 9 of CON4 and pin 13 of CON4/GP16. When I was about to install JP2, I noted a track to pin 2 of CON4, which May 2026  111 is GND. I have confirmed continuity between the two pads. Has there been a circuit diagram change? I wonder if someone there would be able to comment on what looks like an error. (M. F., Gulfview Heights, SA) ● It isn’t marked as such on the PCB, but pin 1 is at the other end of CON4. The clue is that pin 1 has a square pad, while the others are rounded. So that pin of CON4 you are referring to is actually pin 13 (second from the end), which connects to JP2 as expected. The trace to pin 9 is on the underside of the PCB. This probably isn’t helped by the fact that pins 15-18 don’t exist on Advertising Index Altronics.................................43-50 Blackmagic Design....................... 7 Dave Thompson........................ 111 DigiKey Electronics..................OBC Electronex..................................... 5 Emona Instruments.................. IBC Hare & Forbes............................. 11 Jaycar............................. IFC, 12-15 Keith Rippon Kit Assembly....... 111 LD Electronics........................... 111 LEDsales................................... 111 Microchip Technology.................. 9 Mouser Electronics....................... 3 PCBWay....................................... 39 PMD Way................................... 111 Rohde & Schwarz........................ 59 SC ESR Test Tweezers............... 92 Silicon Chip Back Issues........... 78 Silicon Chip Binders................ 111 Silicon Chip PDFs on USB......... 61 Silicon Chip Subscriptions........ 89 Silicon Chip Shop.............. 97, 108 The Loudspeaker Kit.com............ 8 Wagner Electronics................... 101 Next issue of Silicon Chip Next Issue: the June 2026 issue is due on sale in newsagents by Monday, May 25th. Expect postal delivery of subscription copies in Australia between May 22nd and June 9th. 112 Silicon Chip CON4 (on the PCB); they correspond to the four pins at the other end of the LCD module for its (unused) SD card slot. Bench supply upgrade query Can you advise me if Silicon Chip has published a design for a variable-­ voltage, variable-current linear power supply, delivering (say) 0-30V at 0-5A (or so), using something like 2N3055 series pass output transistors? I have recently acquired a WONI bench power supply that appears to be working, but the design is rather woeful, mainly in regard to the voltage control potentiometer. The design of the supply has the pot wired as an adjustable resistor (just two wires from the pot to the PCB) and the voltage variation is far from linear. Rather than playing around with the existing design, I think I would be happier to build and retrofit a Silicon Chip design, which I know would perform properly. (P. W., Pukekohe, New Zealand) ● We have a few designs that may suit you. In October 2019, we published a 45V, 8A linear bench supply (siliconchip.au/Article/12014). It would have plenty of headroom to operate at 5A but, being a linear supply, it is on the bulky side. Alternatively, you could consider the 40V Switchmode/Linear Bench Power Supply (April-June 2014 issues; siliconchip.au/Series/241). It uses a fast-acting final linear stage for output regulation and current limiting, with a tracking switch-mode regulator before it for better efficiency. As such, it doesn’t require a large heatsink. Using a Pico 2 W for the WiFi Time Source I have several clocks I wish to adapt to using the New GPS-Synchronised Analog Clock from September 2022 (siliconchip.au/Article/15466). I was intending to use the WiFi Time Source for GPS Clocks project with it (June 2023; siliconchip.au/Article/15823). Is there any advantage to using a Pico 2 W over the Pico W in this project? If I use the Pico 2 W, what changes would I have to make to the WiFi Time Source project, if any? (P. N., Engadine, NSW) Australia's electronics magazine ● The Pico 2 W uses a different processor from the Pico W (RP2350A rather than RP2040) so you can’t load a UF2 file compiled for the Pico W on a Pico 2 W. It will just ignore it. In theory, the existing source code should compile if the target is changed to the Pico 2 W, but we have not tried that, or tested the result. So we recommend you stick with the Pico W since we know it works and have a compiled UF2 file ready to use. Also, there’s no real advantage to using a Pico 2 W in this scenario, and it costs more. While it’s possible that simply recompiling the code for the Pico 2 W target will be sufficient, there may be breaking changes in the C SDK and its API that mean that more work is needed. The Pico W’s capabilities are more than sufficient for the task, so we don’t see any need to port the code at this stage. The Raspberry Pi Foundation says that the Pico W will remain in production until at least January 2036. Case advice for Roadie’s Test Oscillator Can I use a plastic enclosure for the Roadie’s Test Oscillator project (June 2020; siliconchip.au/Article/14466)? I don’t need it to be drop-proof or rugged. (R. M., Melville, WA) ● Yes, a plastic enclosure is suitable. Note that you must use a type where the lid is attached to the base using screws to comply with safety standards restricting access to the coin cell that powers the oscillator. The cell can be a severe health hazard to young children if they can access it. RF Probe wanted I was just looking at a video from Carlson’s Lab where Carlson troubleshoots electronic circuits with a device he created himself that he calls the Carlson Ultra Probe. It is a very high-gain and sensitive amplifier that uses a coaxial cable as a probe. It can be used as an RF or AF detector and amplifier. I was wondering whether Silicon Chip has created such a project. (P. J., Lenah Valley, Tas) ● We published a similar Audio Signal Injector and Tracer with a matching AM Demodulator Probe in the June 2015 issue (siliconchip.au/ SC Article/8603). siliconchip.com.au “Rigol Offer Australia’s Best Value Test Instruments” New 2026 Products Oscilloscopes New 12Bit Scopes New Up To 13GHz RIGOL DS-1000Z/E - FREE OPTIONS RIGOL DHO/MHO Series RIGOL DSO-8000/A Series 450MHz to 200MHz, 2/4 Ch 41GS/s Real Time Sampling 424Mpts Standard Memory Depth 470MHz to 800MHz, 2/4 Ch 412Bit Vertical Resolution 4Ultra Low Noise Floor 4600MHz to 13GHz, 4Ch 410GS/s to 40GS/s Real Time Sampling 4Up to 4Gpts Memory Depth FROM $ 649 FROM $ ex GST 684 FROM $ ex GST 13,191 Multimeters Function/Arbitrary Function Generators RIGOL DG-800/900 Pro Series RIGOL DG-1000Z Series RIGOL DM-858/E 425MHz to 200MHz, 1/2 Ch 416Bit, Up to 1.25GS/s 47” Colour Touch Screen 425MHz, 30MHz & 60MHz 42 Output Channels 4160 In-Built Waveforms 45 1/2 Digits 47” Colour Touch Screen 4USB & LAN FROM $ 713 FROM $ ex GST Power Supplies ex GST 604 FROM $ ex GST Spectrum Analysers 632 ex GST Real-Time Analysers New Up To 26.5GHz RIGOL DP-932E RIGOL DSA Series RIGOL RSA Series 4Triple Output 2 x 32V/3A & 6V/3A 43 Electrically Isolated Channels 4Internal Series/Parallel Operation 4500MHz to 7.5GHz 4RBW settable down to 10 Hz 4Optional Tracking Generator 41.5GHz to 26.5Hz 4Modes: Real Time, Swept, VSA, EMI, VNA 4Optional Tracking Generator ONLY $ 799 FROM $ ex GST 1,321 FROM $ ex GST 3,210 ex GST Buy on-line at www.emona.com.au/rigol Sydney Tel 02 9519 3933 Fax 02 9550 1378 Melbourne Tel 03 9889 0427 Fax 03 9889 0715 email testinst<at>emona.com.au Brisbane Tel 07 3392 7170 Fax 07 3848 9046 Adelaide Tel 08 8363 5733 Fax 08 83635799 Perth Tel 08 9361 4200 Fax 08 9361 4300 web www.emona.com.au EMONA