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Jaycar reserves the right to change prices if and when required. jaycar.com.au/mediastorage 1800 022 888 Contents Vol.36, No.05 May 2023 20 Avalon Airshow 2023 The biennial Australian International Airshow (hosted in Geelong, Victoria) is one of the world’s top airshows. It showcases amazing new technology from industrial to defence projects. This year it had a flying car! By Dr David Maddison Technology feature 43 UVM-30A UV Light Sensor The UVM-30A ultraviolet (UV) light-sensing ‘breakout’ module detects the intensity of UV solar radiation. When connected to an Arduino, or similar, it can be used to determine the current ‘UV index’. By Jim Rowe Using electronics modules 48 ElectroneX 2023 Electronex is in Melbourne this year, hosted in the Melbourne Convention and Exhibition Centre on the 10-11th of May. Electronex is an important way for companies to show off their products and services in the sphere of electronics design, assembly, manufacture and service in Australia. By Australasian Exhibitions & Events Exhibition outline 32 Dual RF Amplifier The Dual RF Amplifier has two outputs with individually adjusted gains, making it perfect for providing a higher output level on a signal generator. It can also provide better drive strength, or ‘fan out’ to other equipment. By Charles Kosina Test equipment project 62 GPS-Disciplined Oscillator This new GPS-Discipline Oscillator (GPSDO) requires very few discrete components as it is built almost entirely in software. It provides an extremely accurate 10MHz signal with an error in the parts per billion range. By Alan Cashin Test equipment project ElectroneX 2023 Page 48 Page 32 Dual RF Amplifier for Signal generators Page 62 GPS Disciplined Oscillator WIDEBAND Fuel Mixture Display Page 73 2 Editorial Viewpoint 5 Mailbag 72 Subscriptions 87 Circuit Notebook 90 Serviceman’s Log 73 Wideband Fuel Mixture Display, Pt2 The Wideband Fuel Mixture Display (WFMD) uses a Bosch LSU4.9 wideband sensor to show a running engine’s air:fuel ratio and lambda. In the second installment of this series, we cover how the WFMD works by describing the operation of its circuit in detail. By John Clarke Automotive project 80 Songbird This ‘Songbird’ is quick and easy to build, with a simple circuit, so it is perfect for beginners and even more experienced constructors. It sports an aptly designed PCB, and once completed, will burst into song. It is powered via two AA cells and ‘sings’ via a piezo speaker. By Andrew Woodfield Musical toy project 1. A more flexible Flexitimer 2. Jaycar TS1440 soldering stand adaptor 3. Emergency light using tool batteries 4. Raspberry Pi Pico multi-processor stack 100 Vintage Radio 106 Online Shop 108 Ask Silicon Chip 111 Market Centre 112 Advertising Index 112 Notes & Errata Astor APN transistor radio by Ian Batty SILICON SILIC CHIP www.siliconchip.com.au Publisher/Editor Nicholas Vinen Technical Editor John Clarke – B.E.(Elec.) Technical Staff Jim Rowe – B.A., B.Sc. Bao Smith – B.Sc. Tim Blythman – B.E., B.Sc. Advertising Enquiries (02) 9939 3295 adverts<at>siliconchip.com.au Regular Contributors Allan Linton-Smith Dave Thompson David Maddison – B.App.Sc. (Hons 1), PhD, Grad.Dip.Entr.Innov. Geoff Graham Associate Professor Graham Parslow Dr Hugo Holden – B.H.B, MB.ChB., FRANZCO Ian Batty – M.Ed. Phil Prosser – B.Sc., B.E.(Elec.) Cartoonist Louis Decrevel loueee.com Founding Editor (retired) Leo Simpson – B.Bus., FAICD Silicon Chip is published 12 times a year by Silicon Chip Publications Pty Ltd. ACN 626 922 870. ABN 20 880 526 923. All material is copyright ©. No part of this publication may be reproduced without the written consent of the publisher. Subscription rates (Australia only) 6 issues (6 months): $65 12 issues (1 year): $120 24 issues (2 years): $230 Online subscription (Worldwide) 6 issues (6 months): $50 12 issues (1 year): $95 24 issues (2 years): $185 For overseas rates, see our website or email silicon<at>siliconchip.com.au Recommended & maximum price only. Editorial office: Unit 1 (up ramp), 234 Harbord Rd, Brookvale, NSW 2100. Postal address: PO Box 194, Matraville, NSW 2036. Phone: (02) 9939 3295. ISSN: 1030-2662 Printing and Distribution: Editorial Viewpoint The coming AI revolution will soon bring many changes I wrote about Artificial Intelligence recently, in my March editorial (actually, the AI did most of the writing then). I am bringing up the topic again because progress in the field is extremely rapid and it’s becoming more clear over time that it is going to bring massive changes quite soon. Way back then, I wrote “… I don’t think my job is in danger just yet.” but, with the latest developments, I am starting to reconsider! While the development of transistors, ICs, computers and smart devices has had a significant impact on society, I think that AI is going to have an even more significant impact. The AI revolution will probably bring the biggest change since the Industrial Revolution and it will happen fast. Like with the Industrial Revolution, new jobs are going to appear but many existing jobs are going to disappear or shrink drastically. Things like clerical jobs are going to be handled largely by AIs overseen by a handful of people, replacing large teams of people. AIs are already smart enough to do many of those jobs. The AI I evaluated just a couple of months ago was ChatGPT-3. They recently released its successor, ChatGPT-4, which can pass the American bar exam (to become a lawyer) in the top 10%! It also gets very high marks in the SAT exams like English, Maths, Biology, Chemistry and Physics, with a passing score in Calculus. Fields that I expect will see large job losses once AI takes over include data and financial analysis, customer service, banking, some aspects of healthcare, management and administration. I don’t think those jobs will go away completely, but they will probably transform from a large team of people to smaller teams overseeing AIs that perform most of the repetitive tasks. Based on the way ChatGPT-4 is performing, some are saying that it won’t be long before we have Artificial General Intelligence (AGI) – essentially, a computer that is as intelligent as many humans and can perform many of the same tasks as we can. It seems that AI will be able to offload a lot of repetitive and time-consuming tasks that we would otherwise have to do, which is great news for us in terms of raising our productivity. It will probably ultimately raise the standard of living for all of us, but not without a lot of disruptions in the short and medium term. Over time, I think we will see an expansion of the things that an AI can do and as that happens, it will snowball and more and more complex tasks will be able to be completed without human intervention. Imagine what will happen when AIs can do things like browse the internet, access online shopping, interact with third-party software and so on. You would be able to ask it to design a circuit for a particular application, design the PCB, order it, get it assembled and delivered to you, then hook it up to a computer and get it to test it for you. It could do most of that in just a few minutes or perhaps hours. Apply that to many different fields and you’ll start to get an idea of how disruptive the AI revolution might be. I should mention that there are valid concerns about what AIs could do once unleashed in this manner; apparently, OpenAI is putting a lot of effort into figuring out how to prevent AIs from going rogue and limit the damage if they do (as well as addressing bias and privacy concerns). Regardless, that will become a significant issue over the coming years. See this video for more: https://youtu.be/DIU48QL5Cyk by Nicholas Vinen 24-26 Lilian Fowler Pl, Marrickville 2204 2 Silicon Chip Australia's electronics magazine siliconchip.com.au Full speed ahead Trust the new product introduction leader™ to move from concept to prototype at lightspeed au.mouser.com/new 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”. More on underground communications I am an avid reader of your magazine and read Dr David Maddison’s excellent article on Underwater Communications in the March 2023 issue. Consequently, I noticed that his next article (in the April 2023 issue) will concern underground radio communication (siliconchip.au/Series/397). I have been in a caving group for many years and, over that time, we have tried out all sorts of radios and other means of communicating underground. I can give you some information that may be of interest, but I know I am too late for inclusion in David’s next article. In the caving fraternity, although there has been success in certain instances with HF communications (up to 23MHz), long-wave frequencies have proven to be the most reliable. For speech, 87kHz USB (upper sideband) has been decided on as a standard in much of Europe, especially the UK. An example of some of the underground radios used mainly in the UK are: • The Ogofon (outdated): www.arge-hoehle-stuttgart. de/technik.htm • The Heyphone: http://bcra.org.uk/creg/heyphone/ • System Nicola: www.caverescue.org.uk/nicolaradio/ • Cave-Link (Swiss), only for text but has a large range and is quite popular: www.cavelink.com/cl3x_neu/index. php/en/ An Ogofon with a 1m-diameter loop antenna. siliconchip.com.au In addition to these devices, there are several others, some operating on even lower frequencies, mainly commercial units for mines. They include: • X-Ferra (www.xferra.com) • Vital Alert (www.vitalalert.com) The two types of antennas that have been proven to work well are 1-2 meter diameter loops and long wires (called Earth electrodes), about 4-10 metres long, stretched out in two opposing directions and Earthed at each end. The English CREG (Cave Radio and Electronics Group) magazine contains a wealth of information on all sorts of underground communication techniques. That includes ‘base band’ communication, which basically involves using a powerful audio amplifier feeding directly into the Earth and a sensitive receiver in the cave for reception (successfully used in the 1920s). Although you can search the issues for topics, you need to pay for the articles. The URL is https://bcra.org.uk/pub/cregj/covers.html Christopher Ross, Tuebingen, Germany. Comment: it’s pleasing to note how much overlap there is between your letter (and the information you supplied) and what Dr Maddison wrote in the subsequent article. Note on WiFi DC Load design Reader Ray Miller has reported to me a problem with The X-Ferra cave radio operates on 900-1100kHz LSB (lower sideband)/USB with a special antenna (blue). Australia's electronics magazine May 2023  5 the Kelvin voltage sensing arrangement of the WiFi Programmable DC Load from the September & October 2022 issues (siliconchip.au/Series/388). If the main power lead gets unplugged during a test, a substantial negative voltage is applied to the ADS115’s negative voltage sense pin, blowing it up, as well as the 100W Kelvin-to-main resistor. Any significant resistance in the negative lead can also drive the –ve ADS pin below zero and source more than the 10mA that its protection diodes can handle. I have a potential solution that makes the Kelvin sensing truly differential, which will involve a small additional PCB and a couple of minor modifications to the main PCB. I’m also investigating a suggestion from Ray that we use polyfuses (PTC thermistors) for protection. Any readers who have built this device might want to add the PTC thermistors between the Kelvin+ and Kelvin– terminals and the rest of the circuit as insurance while waiting for my more comprehensive solution. The parts I have selected for this are the Bel Fuse OZRE0005FF2C, Littelfuse LVR005NK or Bourns MF-RM005/240. These have a hold current of no more than 50mA and can handle at least 150V DC. Richard Palmer, Murrumbeena, Vic. Latest salvo fired in war between babies and button cells When I saw this stand at my local Bunnings hardware store, I was reminded of the coin/button cell warnings you often publish in the magazine. Edison Zhang, Turramurra, NSW. Praise for older equipment restoration I want to congratulate Brian Healy on his work repairing older hifi/audio gear. He mentions brands like Marantz, Technics, NAD, Quad, Sansui, Yamaha and Thorens (Mailbag, December 2022). Those companies produced some superb equipment, but regrettably, some have been swallowed up by larger companies, and their products sometimes bear little resemblance to the originals. I agree with Brian about the quality of older equipment and am reminded of a comment by a friend of mine who also brings older gear back to life – in many cases, their specifications from 40-odd years ago reveal performance much better than we buy today, so they sound nice and with good restoration, could easily last another twenty years. I have/use some older gear, including a Nakamichi dual-capstan cassette deck playing high-quality cassettes compiled from high-quality sources, older DVD and CD players and loudspeakers from about 40 years ago. I don’t have the expertise/knowledge to repair amplifiers and related equipment like Brian. However, we still restore loudspeakers, appliances, furniture and cars, which is very satisfying. We restored/maintained and operated a car made in 1941 for about 27 years, as our second car, and travelled around Australia in it. We sold it in 2021 and struggled to find a replacement with an equivalent ride on the highway. YouTube provides many interesting videos; Liquid Audio in WA does some wonderful audio equipment restoration work. Mr Electricity (based in Asia somewhere) also publishes some fascinating videos. More power to them all. Thanks for a great magazine. Ranald Grant, Bellbowrie, Qld. Multimeter probe contact problems I wonder if any of the other readers have had this problem. Going back about a least five years, I have had difficulties with the leads supplied with multimeters. Even though the meters were not cheap, I was forced to buy new leads. The problem was that when you set the multimeter to measure ohms and short the probes together, the reading jumps all over the place. When you try to null the reading, you get nowhere. I have tried cleaning the probes and meter contacts, and even moving the lead to different positions in the socket on the meter. Sometimes this made a difference, but most of the time, it did not. It even happened on a DMM I bought about six months ago for about $1000. I was not impressed. I ended up buying a set of leads from Altronics for about $25.00, and they were good. The ohms reading was about 0.24W which could be nulled out. I also bought a set of Keysight test leads from element14 that was OK. Ric Mabury, Melville, WA. Comment: we wonder if some of the multimeters were sitting unsold for a long time and the probes oxidised. It’s interesting that ‘fresh’ probes don’t seem to have this problem, even relatively inexpensive ones. The only other thing we can think of is that they are using low-quality materials, but you wouldn’t expect that with a $1000 meter. LC Meter fault due to less-than-ideal inverter IC A bitter coating on Duracell CR2032 cells is intended to reduce the risk of ingestion. 6 Silicon Chip I had an exchange of emails with reader Geoff Clulow who could not get the LC Meter Mk 3 (November 2022; Australia's electronics magazine siliconchip.com.au siliconchip.au/Article/15543) working. I suggested some things that may be wrong with the device to him, but eventually, he gave up and sent the unit to me. The first thing I noticed when I powered it up was that, during the calibration phase, the numbers on the third line were ridiculous. Despite that, all the signals looked clean. I decided to check the program and loaded the latest version, and then it worked perfectly. However, that was misleading as if I powered it off and left it for a while, it was back to the initial symptoms after powering it back on. I then thought the problem might be that the EESAVE fuse was not set in the microcontroller (the article didn’t mention anything about setting that...). However, that also turned out to be a red herring. It did not do a correct calibration on power-up, but pressing the RESET button resulted in a correct calibration. I changed the program to run the calibration twice on power-up. The first run gave crazy results, but the second gave correct results, and it worked from then on. That was a workaround that I didn’t particularly like, so I continued investigating. Well, that was a classic case of barking up the wrong tree. What caused those crazy calibration numbers on startup? It turned out that the Franklin oscillator was not starting up properly, and when the calibration was repeated, it somehow kicked it into oscillation. After replacing the 74HC04 chip, it now works reliably. The symptoms certainly sent me down the wrong alley. Doing measurements with my 1% capacitors, I get a reading of 221pF for a 220pF capacitor; two 220pF capacitors in parallel read 443pF. Two 2200pF capacitors in series read 1103pF. It’s gratifying to see that other peoples’ builds match the accuracy of the prototype. And another lesson learned! Charles Kosina, Mooroolbark, Vic. Comment: that shows how critical components can be when used in oscillators. The 74HC04D hex inverters we supply in kits are made by Toshiba and come from a reputable vendor, so we don’t think anything would be wrong with them. It might be a case of theoretically compatible parts from different manufacturers having slightly different characteristics, or maybe it was just a dud. Fixing a newly built LC Meter I built the Wide-Range L/C Meter (June 2018; siliconchip. au/Article/11099) but ran into some problems. I found that the stackable headers were not making satisfactory contact with the Arduino Uno board, so I replaced them with separate wires, but only for the active pins. It then appeared to read low-value inductances and highvalue capacitances correctly. However, when a capacitor of 1μF or lower was attached, the Meter acted as if nothing was connected. After some troubleshooting, I finally managed to fix this by replacing RLY3. I realised the relay was probably faulty because the oscillator frequency did not drop when attaching a capacitor in capacitance measuring mode. After replacing the relay, it was reading 60pF with nothing attached. This initially caused me some confusion until I realised that it was the stray capacitance, so I used the G option in the manual calibration to eliminate it. I am very pleased with the operation of the Wide-Range L/C Meter now that I have it working correctly. I never expected a brand-new component to fail, but I guess you 8 Silicon Chip Australia's electronics magazine siliconchip.com.au PRECISION MADE EASY Next-generation oscilloscope for accelerated insight NEW R&S®MXO 4 The R&S®MXO 4 Series is the first of a new generation of oscilloscopes that excels in both performance and value. The instruments deliver a once-in-a-decade engineering breakthrough for accelerated insight. The R&S®MXO 4 Series oscilloscopes utilise leading-edge technologies to achieve fast and accurate results. Custom technology and innovative features in our oscilloscopes quickly boost your understanding of circuit behaviours. More at: www.rohde-schwarz.com/product/mxo4 Series oscilloscope have to expect the unexpected when it comes to electronic circuits. Dean Beavis, Wellington, NZ. happy. They had been able to overhear communications from outside the building with their special equipment! Brian Dunn, Noarlunga, SA. Praise for Jamieson Rowe Servicing at sea I first came across Jim Rowe as a teenager reading Electronics Australia magazine. He regularly wrote in the magazine then, and now over 50 years later, Jim is still making a great contribution to Silicon Chip. His articles are always well-researched and well-written. I just wanted to acknowledge Jim’s excellent work and dedication. Paul Howson, Warwick, Qld. Recollections of a submarine communications system In the late 1960s, I was in charge of communications through Alice Springs, and we were advised that new submarine communications were to come online. As we were running north/south, we might have encountered some problems with our carrier systems. On one three-channel system from Adelaide, we did experience some problems but on one channel only. This channel had a carrier frequency just below the submarine system, which caused a low-level tone pulse to be demodulated and heard at the Alice Springs end. However, the level did not disturb the conversation. This three-channel system worked in the frequency range of 7-30kHz. The lower frequency channels worked from Alice to Adelaide, and the higher frequency worked the other way around, so that was why we could still hear OK. Also about this time, I had a query from a US weather station (!) asking whether I knew of anything that could cause a 1Hz signal to be generated around the district. I could not think of anything. The station had a security check, with the result that they requested I arrange the removal of spare wires in the cables for the telephone system. That was impractical, so we eventually Earthed the spare wires, and security was 10 Silicon Chip One of my favourite sections in the world’s best electronics magazine, Silicon Chip, is the Serviceman’s Log by Dave Thompson. Whether it is knowing that others go through more pain than I do repairing electronic equipment or anticipating a successful repair, it is a great read. The photo below is of my model of the HMAS Swan, which was built at the Williamstown Naval Dockyard in the mid-1960s. In my wanderings around the dockyard, I happened on the so-called Sail Loft, which did fibreglass work following the demise of sails on warships some hundred years earlier. They had a 1:48 scale fibreglass mould of the River class ships – Derwent, Swan, Yarra, Parramatta, Stuart and Torrens. The fibreglass models were sheeted in copper and then used to test radar and radio antenna mounting positions. The sail loft foremen allowed me to make a 1:48 hull for my model of the HMAS Swan. The only proviso was that I could not include the new Mulloka Sonar Dome on the hull. After leaving the wheatlands of the Wimmera back in 1974, I gave up studying and headed west to work in the iron ore mines. I wound up working for a French crew on a diamond drilling rig north of Kununurra. Tiring of my French workmates teaching me army rifle drills and coaxing me to eat roast snake, I headed home and studied to be an electronics technician at the Royal Melbourne Technical College. When we finished, most of my mates went to work at Telecom or the Department of Aviation, but somehow I got a job building warships at the Williamstown Naval Dockyard in Melbourne. It was an exciting place to work, with lots of shenanigans on the go, no doubt because the Painters and Dockers were running the show, in their minds at any rate. My boss Bruce had some kind words of advice before I set sail on my first sea trials on the HMAS Parramatta after her half-life refit. “G’day Gerard. You are going out on your first sea trials today?” I nod. “Well, it’s a serious undertaking for a young technician. The navy boys are going to hammer the old girl before they re-commission her back into the Royal Australian Navy, so you have to be on the ball and keep things running.” My speciality areas were the ELWO Long Range Radars and radio and teletype communications. Bruce brings me back to reality. “OK, the Petty Officer tells you his ELWO radar is down. What’s the first thing you reach for to fix the problem?” I was keen and confidently answered, “My AVO Meter, Bruce.” “No, the first thing you take is your brain. You’ve trained and worked on the ELWO, so you should focus your mind’s eye on every part of the radar. What’s the next thing?” “AVO Meter”, I confidently reply. “No, your ears. Ask the Petty Officer to describe the problem. This will point to where you should start looking. Now, what do you reach for when you open the radar cabinet?” Surely I thought it was time to pull out my trusty AVO Meter, so I mentioned it again! 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XC4514 ONLY 7 $ 95 Batteries not included SINGLE 18650 BATTERY HOLDER SWITCHED 4XAA BATTERY ENCLOSURE WITH USB PORT PH9205 $3.50 MP3083 $5.95 SWITCHED 4XAA BATTERY ENCLOSURE WITH DC PLUG PH9283 $6.75 3.7V 18650 2600MAH LI-ION BATTERY SB2308 $17.95 Shop at Jaycar for: • Step Up and Step Down DC-DC Converters • Huge range of Batteries and Battery Holders • Great selection of USB and DC Connectors & Leads • Regulated DC Plugpacks & Lab Power Supplies Explore our full range of products to power your projects, in stock on our website, or at over 110 stores or 130 resellers nationwide. jaycar.com.au/powerprojects 1800 022 888 Prices correct at time of publication but are subject to change. Jaycar reserves the right to change prices if and when required. “No, Gerard… your eyes. During sea trials, the ship is being pushed to the limit. It will twist and lurch, and when the 4.5-inch Vickers guns fire, the vibration shakes everything loose. Look for connectors out of place, waveguides jammed, valves dislodged –anything that doesn’t look right. Once you have done all of the above, what do you reach for to find the fault?” By now, I was sure it wasn’t my AVO Meter, so I thought for a few seconds and mentioned using my nose to smell burning wires. Bruce looked at me and shook his head. “No, grab your AVO Meter you idiot.” He laughed, and we went below deck. Bruce wasn’t wrong. The Captain had it in for us Willie Dockies – he had the Parramatta going flat out doing highspeed turns and firing guns. The old boat was shuddering and shaking and, being locked below decks, we didn’t have a clue where we were or where we were going. To add to the excitement, every few minutes, the PA would blare out instructions: “Frexercise, frexercise, frexercise – fire in the forward hold – fire in the forward hold.” Several sailors immediately jumped up, grabbed their kit and charged off to the forward hold. Some carried fire fighting gear, others first aid kits. We kept out of the way and watched the radar PPI screens (Plan Position Indicators), trying to work out where we were. Around lunchtime, we lined up in the mess to get a few dollops of sea tucker on our trays, but before I got served, the PA blared out again: “Frexercise, frexercise, frexercise – Action Stations, Action Stations, Action Stations.” The cook froze, dropped his apron on the floor, shook his head at me and then ran through the forward watertight door. Behind him, a young sailor swung the door shut, pulled the door latches closed and stood to attention. “Forward Hold Door Secure Chief!” yelled the young sailor standing to attention next to the door. The Parramatta started shaking and heeled over to the left. As a Kawasaki 900 motorcycle rider, I naturally assumed we were leaning into a left-hand turn. Bruce shook his head and said the ship was doing a hard right turn. A burst of machine gun fire woke us up. At that moment, the reality of life as a sailor in the Royal Australian Navy dawned on me. One day in the future, should our sailors face real action, they will stand to their posts in sealed, watertight compartments until the action is over. If the ship is struck, those in the punctured compartment cannot escape through the sealed doors because this might endanger the ship and its entire crew. So, when next you meet a young Australian, or for that matter, a Kiwi sailor with their ship’s name embroidered on their cap, thank them for looking out for us. I have a repair story from my days in the dockyard. It has everything: suspense, pathos, humour – well, it is about fixing a fault anyway. I’ll send it in when I’ve had a chance to write it up. Gerard Dean, Glen Iris, Vic. Reader won’t let health problems get in the way of welding! I have been a Silicon Chip reader for many years and hope you can help answer a question regarding a Spinal Stimulator that I recently had fitted. 12 Silicon Chip Australia's electronics magazine siliconchip.com.au The unit is called a Nevro HFX. It works well on my lower back pain, reducing it by approximately 70%, and I’m quite happy so far. My biggest problem is that I’ve been told not to do any arc welding as it could interfere with the unit. I asked for any information they could give me on the possible effects, but all they were prepared to do was give me an electrical spec sheet on the unit. I’m told that it is MRI safe as long as the MRI power is turned down to 1.5 teslas and the Nevro HFX is turned off via its remote. I have done some tests on EMI around the TIG welder I was frequently using and found figures up to 0.5 gauss and 500V/m (using a relatively cheap test meter from China). Other things in my shed, like AC motors and fluorescent lights, have nearly double those readings up close, but they tell me that devices like that shouldn’t cause a problem. The HFX has a built-in magnetic sensor that is meant to turn it off if I get too close to a strong magnetic field; things like airport security etc. I did some welding while I had a trial unit fitted for a couple of weeks and had no noticeable problems, but the Nevro reps freaked out somewhat when I told them. Still, the unit’s memory showed no adverse events, and I didn’t die or have smoke come out of my ears. I’m sure there may be some interest in electronics land as to the workings of these devices, and I would love to see an article on them. I would be happy to forward my experience. I would also be happy if you could answer my question about deciphering the EMI values. Name and location withheld for privacy reasons. Comment: We looked at the supplied information on the unit, and it appears that they’ve tested it up to certain field strengths that you might encounter in day-to-day life and (understandably, we think) are unwilling to give any guarantees beyond that. We are reluctant to provide medical advice, but we think readers will be interested in your story. Safely using ECGs & EEGs The February 2023 issue was an excellent magazine, as always. I have been a reader across the various magazine incarnations since 1966. I have comments regarding the Heart Rate Sensor module review (February 2023 issue; siliconchip.au/Article/15662). Most ECG monitors have patient isolation from mains power and external voltages that can cause excessive and potentially fatal leakage currents through a patient using 3M Red Dot or other conductive electrodes. Unfortunately, the module review doesn’t mention leakage currents, the need to power the unit from a quality power pack and the need to avoid touching other equipment when you have yourself connected to the monitor. Most plugpacks, for example, have a ‘touch current’ level of 100μA, so you need to build in patient protection with isolation resistors. The data sheet for the Analog Devices chip mentions selecting a series leakage current protection resistor to ensure <10μA flows from a potential internal chip fault. The module incorporates such resistors, but they do not protect from a fault in the power supply. The electrodes usually contain a conductive gel, and often an abrasive is included on the rear so that the top layer of the skin can be scrubbed off to ensure good contact, lowering the resistance compared to simply touching exposed metal. 14 Silicon Chip For one ECG test I had a while ago, the nurse used a sheet of abrasive usually used for cleaning pots and pans (the abrasive included with ECG pads cost more!). So the skin contact is typically very good. Briefly, the primary medical safety standard is IEC60601-1 and ECGs are covered by IEC60601-2-25, a collateral standard. These standards require extensive risk analysis to cover every eventuality in use. The typical input/output isolation test voltage is 4000V for a CF (cardiac floating) connected product. CF rating requires an isolated input and mains isolation. The leakage current tests apply 264VAC directly to the ECG electrodes as a worst-case scenario, where a patient may be connected to an ECG monitor and external equipment touched by the patient is faulty. The intention is to protect the ‘patient’ from unintended current flows across the heart. Suppose the ‘patient’ connects the module to a PC (an external conduction path). In that case, the risk is that, while in use, the patient touches an external device with higher voltages, such as an unearthed appliance, which typically has mains leakage currents at up to 100μA present due to the input AC EMI filters. The module and PC create a return path via the USB or other data connection. In this case, the series resistors are vastly undervalued. If an external device is faulty, much higher currents are possible. The best solution is to suggest to readers that the lowest risk approach is to use the ECG module + Arduino + PC alone and not touch any other external device while connected to the electrodes. Braham Bloom (EmiSolutions), Russell Lea, NSW. More on magnetic amplifiers/regulators The article on Magnetic Amplifiers in the January 2023 issue (siliconchip.au/Article/15620) was fascinating. I have since found a free download of another reference at http:// tubebooks.org/Books/mag_amp.pdf (1.3MB). It’s “Magnetic amplifiers: principles and applications” by Paul Mali (General Dynamics Corp). Dave Horsfall, North Gosford, NSW. Response to letter on AM & DAB+ Regarding Denis McCheane’s letter on AM interference and poor DAB+ sound quality in the February issue (p7), the interference to AM was originally just from lightning. Now we have EMI from high-voltage power lines, petrol engine ignition systems, and virtually everything else using electricity, including electric vehicles. All of the EVs available in Australia have DAB+/FM/ Bluetooth receivers but no AM. It is being justified by the electronic interference generated by the vehicle causing bad AM reception. So much for shielding and electronic filtering of inverters to power the motor! All ABC and SBS stations in capital cities are on DAB+ with AM simulcast, including ABC local radio, ABC Radio National and ABC News in nearly all capital cities. The real problem is in regional areas where there are 85 commercial AM and 114 ABC AM transmitters covering around nine million people. In remote Australia, there are one million people with only VAST satellite ABC/SBS radio, which cannot be received while moving outside towns and villages. 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Explore our full range of replacement power supplies, in stock at over 110 stores and 130 resellers or on our website. jaycar.com.au/replacementpsu 1800 022 888 Prices correct at time of publication but are subject to change. Jaycar reserves the right to change prices if and when required. or non-existent. That is why the ABC high-frequency (shortwave) broadcasts should not have ceased in 2017. Digital Radio Mondiale, using the now-vacant analog TV channels 0, 1 & 2, could replace all existing regional broadcasts from existing TV/FM transmitter towers. A single modified FM transmitter can carry 18 programs, the same number that the ABC/SBS radiate from single DAB+ transmitters in capital cities. I have heard complaints about the poor sound quality of DAB+ transmission many times. They seem to be based on the bit rate rather than describing the type of sound and what makes it sound wrong. While Southern Cross Austereo has many music streams at the lowest possible bit rate, ABC Classics is now HE-AAC at 120kbit/s, the highest bit rate I have seen from HE-AAC compressors. ABC/SBS have eight programs allocated at least 72kbit/s each. Have you listened to these stations on a DAB+ car radio or headphones? As for TV, the picture quality of HD broadcasts has been improving with improvements in the MPEG4 encoders’ ability to predict image changes. I agree that it is time for Australian TV broadcasters to push for all new receivers to be capable of receiving DVB-T2 modulation and HEVC video coding so that they can transmit UHD (4k) TV. The broadcasters are keeping standard definition MPEG2 transmission for earlier TVs. The TV broadcasters don’t know how many viewers cannot receive HD TV, which has been available for 12 years. As for streaming, there are large areas of Australia with low bit rates, and streaming programs on smartphones is not free; it consumes your data allowance. I would lastly like to remind you that if all broadcasting were to stop, the internet (particularly mobile) does not have the capacity for 26 million individual programs sent to users. Alan Hughes, Hamersley, WA. Warnings about variacs I purchased a variac from Jaycar (Cat MP3080) but I was unsure about its ratings. The output socket has 10A stamped on it, but the internal fuse is 3A, so you can’t draw anywhere near 10A. I later realised that the 500VA rating implies it can only deliver up to about 2A (500VA ÷ 230V AC ≈ 2A). Still, I am concerned that some people purchasing that device (or a similar variac) might not realise that and quickly blow the fuse by overloading the output. I wonder why they used a 3A fast-blow fuse rather than, say, a 2A slow-blow fuse. I also hope anyone using this type of variac realises it does not provide isolation between the input and output and therefore, it is not a safety device. Evan Bennett, Balga, WA. Any kind of intelligence would be helpful The last verse of Eric Idle’s “Galaxy song” goes something like “… pray that there’s intelligent life somewhere out in space, ‘cause there’s bugger all down here on Earth!” That makes me realise that introducing artificial intelligence (AI) to our bureaucracies has the potential for a vast improvement. SC Marcus Chick, Wangaratta, Vic. S E e M lec e us St elb tro a an ou ne t d A rn x 25 e We offer... Discover New Technologies in Electronics and High-Tech Manufacturing See, test and compare the latest technology, products and turnkey solutions for your business SMCBA CONFERENCE The Electronics Design and Manufacturing Conference delivers the latest critical information for design and assembly. 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Jaycar reserves the right to change prices if and when required. Dr David Maddison presents the 2 0 2 3 Australian International Airshow (in Avalon) South Australia” at https://youtu.be/ tAFZuq9Wtpw Australian Department of Defence Space Command The Australian International Airshow is usually held every two years at Avalon Airport near Geelong, Victoria, about an hour’s drive from Melbourne. It is considered one of the world’s top airshows and showcases amazing new technology, detailed in this article. This year they even had a flying car! i generally attend each Avalon Airshow, although the last one was cancelled due to COVID-19. I covered previous Airshows in the May 2013, May 2015 & May 2019 issues (siliconchip. au/Series/399). This article will not go back over anything I previously described; I will only list what was new this year. The Australian space program suffered a huge setback after Australia was one of the first countries to launch a satellite in 1967, WRESAT (see our October 2017 issue; siliconchip.au/ Article/10822). An ignorant politician decided there was no future for an Australian space program (well, he made sure of that!). It was one of the worst decisions made in Australia. Still, judging from 20 Silicon Chip what we saw at the Airshow, the Australian space program is now back! Let us approach them alphabetically since there are so many topics to cover. AtSpace AtSpace (https://atspace.com.au/) was founded in 2021 in Adelaide. They have developed the Kestrel I and Kestrel V launch vehicles (Fig.1) with payload capacities and maximum altitudes of 150kg/350km and 350-390kg/700km, respectively. The Kestrel V payload is 350kg for a Sun-synchronous orbit (SSO) or 390kg for a low Earth orbit (LEO). Kestrel I has a maximum take-off weight of 3036kg, while the V has a maximum take-off weight of 35,000kg. See the video titled “AtSpace in Australia's electronics magazine Like the USA and a few other countries (Brazil, Canada, Germany, Israel, Japan, Luxembourg, Netherlands, Thailand, Turkey and the UK), Australia now has a Space Command (www. airforce.gov.au/about-us/defencespace-command), established on the 18th of January, 2022. It has members of the Navy, Army, Air Force, the Australian Public Service and industry under an integrated headquarters housed by the Royal Australian Air Force (RAAF). Its roles (roughly) are to develop and advocate for space-specific priorities across government, industry and allies; train people as space specialists; conduct strategic space planning and determine priorities; ensure the design, construction and operation of Defence space capabilities are following Defence standards and limitations. Defence Space Command’s mission is to “Prepare space power to secure Australia’s interests in peace and war.” It also exists “To assure Australian civil and military access in space, integrated across Government, and in concert with allies, international partners and industry.” The space command facilities are: • Space Surveillance Telescope, Exmouth (Fig.2) was originally at the White Sands Missile Range in New Mexico, USA from 2011. However, in 2017, it was dismantled and brought to Exmouth, WA, to the Harold E. Holt Naval Communication Station, a joint Australian/US military facility. siliconchip.com.au Fig.1 (left): the Australian-developed Kestrel launch vehicle. Source: https://atspace.com.au/dedicated-launch Fig.2 (above): the Space Surveillance Telescope at Exmouth, WA. Source: https://w.wiki/6Suc (CC BY-SA 4.0) It is part of both the Space Command and the US Space Surveillance Network. It enables the tracking of space objects and the determination of any threats they may pose. It is remotely operated by RAAF, 1 Remote Sensor Unit at Edinburgh, SA. The telescope has a 3.5m mirror (see Fig.3). • The C-band Radar, Exmouth (see Fig.4) was moved to the Harold E. Holt Naval Communication Station in 2014. It operates at 4-8GHz and is used to identify and track space objects, among other functions. It is owned by the USA but is now operated remotely by RAAF, 1 Remote Sensor Unit at Edinburgh, SA. One of its missions was to track the Buccaneer Satellite, a 3U CubeSat (34 × 10 × 10cm, 4kg), launched on the 18th of November 2017 as a joint venture of the University of New South Wales (UNSW) and the then Defence Science and Technology Organisation (DSTO). Buccaneer’s purpose was to provide calibration data for the Jindalee Overthe-Horizon Radar Network (JORN). It is also part of the US Space Surveillance Network and is operated cooperatively with the USAF 21st Operations Group, 21st Space Wing. This radar started as part of a NASA tracking station in Carnarvon, WA in 1963. After that station closed in 1974, it was moved to Florida in the USA as a test radar, then to Antigua in the Caribbean to support Eastern Range launches from Cape Canaveral. It was returned to Australia in 2014. • The Satellite Ground Station – West (Fig.5), at Kojarena, provides a ground link to satellite constellations such as the Wideband Global SATCOM (WGS), visible from Western Australia, Fig.3: a computer rendering of the 3.5m mirror used by the Space Surveillance Telescope. Source: https://w.wiki/6Sud the Indian Ocean for the Australian Defence Force (ADF) and our allies. It operates in conjunction with Satellite Ground Station – East for satellites visible from eastern Australia, located in Kapooka Military Area near Wagga Wagga, NSW. The WGS is operated by the US Department of Defense Space Force system, operated jointly with Australia and Canada. • Koonibba Test Range, Koonibba and Whalers Way Orbital Launch Complex, Eyre Peninsula (see the section on Southern Launch below). • Satellite Ground Stations for R&D at Edinburgh, SA. This DSTG (Defence Science and Technology Group) facility performs R&D to improve Defence satellite communications, such as developing the Cortex system. Fig.5 (left): Satellite Ground Station – West, Google Earth image. Source: https://adbr.com.au/wa-satcomground-station-declared-operational/ Fig.4: the C-band radar at Exmouth. Source: www.afspc.af.mil/News/ Article-Display/Article/1457949/cband-holt-radar-one-year-on/ siliconchip.com.au Fig.6 (right): Mission Control, the Responsive Space Operations Centre (RSOC) run by Saber Astronautics. Source: Saber Astronautics siliconchip.au/ link/abkw Australia's electronics magazine May 2023  21 Fig.7: Silentium Defence Oculus Observatory, MidMurray Region, SA. Source: www.industry.gov.au/news/ world-class-observatory-track-space-objects This system “combines communications planning information with live spectrum monitoring and equipment control in a form tailored to the workflow requirements of Defence satellite network operators” and provides “detection of anomalies across Defence’s satellite network”. • The Australian Geospatial Intelligence Organisation (AGO) Ground Station, Edinburgh, SA, requests and receives commercial satellite imagery for use by Defence and the intelligence community. It has ground stations at Edinburgh, Woomera (SA) and Tindal (NT). • Australian Space Agency Mission Control, Adelaide (“Lot 14”) – Fig.6 – is run by Saber Astronautics for the commercial space sector and offers the control of satellites and space traffic services for the regions. Saber refers to it as Responsive Space Operations Centre (RSOC). • Silentium Defence Oculus Observatory, Mid-Murray Region, SA – Fig.7 – is a passive radar observatory that uses pre-existing television and radio signals to detect and track low Earth orbit objects. The Oculus observatory uses Silentium’s MAVERICK S system, a world-first commercial-scale Space Situational Awareness (SSA) passive radar. The observatory also has an Astrosite neuromorphic imaging sensor from Western Sydney University that emulates the human eye to detect objects visually. The observatory uses northern hemisphere data from the Swedish Space Corporation to complement tracking. • No.1 Space Surveillance Unit (1SSU), RAAF Edinburgh, is Australia’s first Joint Space Unit and will contribute to “advanced space situational awareness, allowing the 22 Silicon Chip Fig.8: the BlueRoom augmented-reality simulator for medical training. tracking of space assets and debris”. • SATCOM Satellite Operations, HMAS Harman, near Canberra, plays a key role in communications across the Australian Defence Force. Satellite communications for the ADF and allies are managed over various commercial and military satellites, including Optus-C1, Intelsat-22, Inmarsat and WGS satellites (mentioned earlier). • Headquarters Joint Operations Command (HQJOC), Bungendore NSW, is responsible for command and control of Australian Defence Force operations worldwide and is also the headquarters of the Australian Space Operations Centre (AUSSpOC). • Royal Australian Navy Deployable SATCOM can operate from various vessels. • Army Portable SATCOM – the Australian Army has portable ground stations for satcom. • C-130J Hercules Airborne SATCOM – RAAF Hercules are equipped for satcom. • Gilmour Bowen Launch Site is located at Abbot Point State Development Area in Queensland and is suitable for launches to the east over the ocean. The first launch is expected this year. • Arnhem Space Centre, East Arnhem, is a site in the Northern Territory suitable for all types of launches. It was used by NASA to launch sub-­orbital sounding rockets in 2022. Defence Space Command invited visitors to download the following documents: • Australia’s Defence Space Strategy: siliconchip.au/link/abkr • Space Power eManual: siliconchip.au/link/abks Australian Space Agency The Australian Space Agency (www. industry.gov.au/australian-­s paceagency) was established on the 1st of July 2018 to coordinate civil space matters across government entities and support the growth and transformation of Australia’s space industry. BlueRoom simulator Australian company Real Response (www.realresponse.com.au) demonstrated their BlueRoom “mixed reality” simulator (see Fig.8) for training Army, Navy and Air Force medics, among others. Students can enter a virtual-reality environment while still using their hands to interact with ‘patients’ and equipment. A trainer can create any situation they want, or change the patient’s condition, and students can interact by inserting an IV drip into a trainee dummy, for example. Boeing MQ-28A Ghost Bat We mentioned the Boeing MQ-28A Ghost Bat in the 2019 Airshow article. Still, this artificial intelligence (AI) based unmanned aerial vehicle remains under development by Boeing Fig.9: the Boeing MQ-28A Ghost Bat drone can fly independently or as a ‘wingman’. Source: Boeing siliconchip.au/ link/abkx Australia's electronics magazine siliconchip.com.au Fig.10: a Capella Space SAR image of a flooded area close to the Hawkesbury River near Windsor, NSW, taken on 24/03/2021 at 1:24 pm UTC (24 minutes past midnight local time). The centre coordinates are 33.594746S 150.817394E. Australia (www.boeing.com/defense/ MQ-28/) for use by the RAAF (Fig.9). It will either fly alone or as part of a formation to support and protect aircraft such as the RAAF’s F-35A, F/A18F, E-7A and KC-30A. It is 11.7m long and has a range of more than 2000nmi (nautical miles). The US Air Force is also interested in this drone. Capella Space Persistent Radar Capella Space (www.capellaspace. com) has a constellation of satellites that use Synthetic Aperture Radar (SAR) to provide all-weather, day-andnight imaging of the Earth for purposes such as military planning, energy and natural resources, infrastructure monitoring, humanitarian and disaster relief, insurance and risk assessment, maritime domain awareness and commodities management. The company provides customers with tasking software so they can decide what images to take, where and when. Capella has a gallery of images you can peruse at www.capellaspace. com/gallery/ Imagery is taken on X-band frequencies (8-12GHz, bandwidth Fig.11: a computer rendering of the Capella SAR satellite. Source: www.capellaspace.com/capella-space-unveilsnext-generation-satellite-with-enhanced-imagerycapabilities-and-communication-features/ 500-700MHz) and has 0.214m resolution at slant angles, 0.31m for normal angles, with low noise and high contrast – see Figs.10 & 11. Each satellite uses a 3.5m mesh antenna and inter-satellite optical links. Currently, seven 112kg satellites are in orbit, plus one prototype; ultimately, 30 are planned. Radio astronomers have expressed concerns about radio emissions from these satellites. Corvo Precision Payload Delivery System (PPDS) An Australian company, SYPAQ (www.sypaq.com.au), produces disposable drones for around $1,000 each (although some sources reckon they’re closer to $5000). They are intended for use as delivery systems for humanitarian or other supplies. The drone is called the Corvo Precision Payload Delivery System (PPDS) – see Fig.12 – and its mission is the “delivery of supplies and equipment into areas traditional logistics capabilities cannot reach.” They are made from waxed cardboard, use a battery to power a propeller, and are guided by GPS. They are delivered as a flat-pack that needs to be assembled. Once assembled, they can autonomously fly up to 120km and land softly to deliver supplies. The payload capacity is either 3kg or 5kg, depending on the model. Australia is sending many of these to a certain conflict zone right now. They can be adapted for intelligence, surveillance and reconnaissance missions. Still, according to a report from an ambassador quoted on radio 3AW (siliconchip.au/link/ abkd), they are being used with lethal payloads. CubePilot CubePilot (www.cubepilot.com) is an Australian company that produces professional-grade autopilots for autonomous unmanned vehicles (see Fig.13). Multiple vehicle types are supported, such as fixed-wing, multicopters, VTOL aircraft, submarines, rovers and boats. Curtin University and Nova Systems Researchers at the International Fig.12 (left): the Corvo cardboard disposable drone on a catapult, ready for launch. Source: https:// corvounmanned. com.au/ Fig.13 (right): the CubePilot autopilot can be used to control a variety of airborne and waterborne platforms. siliconchip.com.au Australia's electronics magazine May 2023  23 Fig.14: a Nova Systems passive array sensor for tracking objects in low Earth orbit, one of 2400 planned. Source: ICRAR Curtin siliconchip.au/link/abky Centre for Radio Astronomy Research (ICRAR) at Curtin University have developed a passive sensor for Space Domain Awareness (SDA). Its purpose is to track space debris or satellites in low earth orbit to warn of potential collisions (see Fig.14). The system uses signals from commercial FM radio stations that reflect off objects in space. It can also monitor space weather. ICRAR has partnered with Nova Systems for this project; see siliconchip. au/link/abke A prototype is being established at Nova Systems’ Space Precinct in South Australia’s mid-north; it is an adaptation of the Curtin University-led Murchison Widefield Array (MWA), a low-frequency radio telescope. Initially, 512 antennas will be installed, with an eventual 2400 planned. Droneshield The Australian company Droneshield (www.droneshield.com) offers a range of C-UAS (Counter-Unmanned Fig.15: the DroneGun Tactical is designed to take down threatening drones by jamming RF control or satellite navigation signals. It’s one of the products offered by Droneshield. Aircraft System) products to detect and disable hostile aerial vehicles that are radio-­controlled (on ISM bands) or guided by GNSS (satellite navigation such as GPS). Detection may be by optical, radar or RF means. Their products come in various forms, such as a handheld ‘gun’ (Fig.15) or a fixed ‘sentry’ (see Fig.16) unit to protect a designated area. Disruption ranges depend on the device and start at 1km for the Dronegun MKIII. Detection ranges are up to 4km for the Repatrol MKII (lower in a high RF environment). Such devices severely interfere with the radio spectrum on the ISM and GNSS bands, so government authorisation is required to use them. Elbit Land Systems Among many products they make, Israeli company Elbit makes the Iron Fist APS (Active Protection System) which will be used on Australian Redback Infantry Fighting Vehicle (IFV), if it is selected (see below). When a Silicon Chip F-35A Lightning II fighter jet The RAAF is acquiring 72 F-35A aircraft with “full operational capability” expected by the end of 2023. They are currently operating about 60 F-35As. By the end of 2022, 23,000 flight hours had been logged, compared with all allies’ total global flight hours of 610,000. A recent “Red Flag” exercise in the USA demonstrated a ‘kill ratio’ of 20:1 against simulated enemy aircraft. See the video titled “Air Force F-35 interoperability with US – Exercise Red Flag Alaska” at https://youtu. be/lLibFSkATH8 Gannet Glide Drone The Gannet Glide Drone (Fig.17) from Australian company Skyborne Technologies (www.skybornetech. Fig.17: an unpowered Gannet Glide Drone, launched from other aircraft. Source: www. skybornetech. com/news/ gannet-gliderprogramconductssuccessfulflighttests/2022 Fig.16: DroneSentry provides autonomous detection of drones via optical, radar and RF (top section) means. The optional DroneCannon (bottom section) is then used to defeat hostile drones. 24 threat is detected and about to strike the vehicle, an explosive interceptor is launched against it. See the video titled “Elbit Systems / Iron Fist APS” at https://youtu.be/e4_kFEw33s4 Australia's electronics magazine siliconchip.com.au Fig.18: com) is a “new class of low-cost, Skyborne’s swarming air-launched effects for a Cerberus swathe of operational scenarios”. Once GLH released, it can travel 2.4km if dropped Unmanned from an altitude of 1000ft (~300m) or Aerial 1.3km if dropped from 650ft (~200m). Vehicle It is silent and stealthy. carrying It can be dropped as a swarm and a 40mm can carry electronic payloads such grenade as electronic warfare, communicalauncher. tions or explosive payloads such as shaped charges to penetrate armour. The glide velocity is 90-110km/h and the payload is up to 600g with a total mass of 1.9kg. It can use GNSS (global navigation satellite system) or MEMS (microelectromechanical system) based INS (inertial navigation system) if GNSS signals are jammed. Uniquely, it sweeps the wings to roll and turn. See the video titled “Gannet Glide Drone Press Release” at https://youtu. be/­fuvv6zPP49s Skyborne also produces a man-­ portable tactical UAV, the Cerberus GLH Unmanned Aerial Vehicle, which can carry weapons payloads such as Fig.19: the Honeywell Boeing 757 test aircraft at the Airshow. Note the third shotgun shells or 40mm grenades (see engine pod at the top of the fuselage, to the right of the word “IT”. No engine was mounted there at the time. Fig.18). Also see the videos titled “CHAOS Ground Firing Campaign” at https:// youtu.be/-jk9IpZJCgQ or “HAVOC 40mm Campaign 2” at https://youtu. be/PsZzCMhwnpE and the videos at www.skybornetech.com/uxv-weapons Honeywell I was invited for a ride on Honeywell’s legendary Boeing 757 test aircraft to see Honeywell’s latest aviation technology. It is the fifth 757 ever made, acquired by Honeywell in 2005 and “40 years young”, with a tail number of N757HW. This aircraft is renowned in the industry and externally is unusual in that it has a pod on the fuselage to mount a third turbofan or turboprop engine for testing purposes – see Fig.19. On-board data acquisition equipment can record over 1,000 channels of engine test data. Inside, the aircraft has only a small number of seats but also has engineers’ workstations, equipment bays and empty areas to mount other test equipment if necessary (see Fig.20). It would be wasteful to test just one thing on a flight, so a typical test flight might involve testing a weather radar, an engine and a satellite communications system, all at the same time. siliconchip.com.au Fig.20: one of the workstations on the Honeywell 757 aircraft used to monitor tests during flight. Test flights can last as long as the fuel capacity allows and can go anywhere in the world. The aircraft is quite lightweight because it lacks passenger seats, inner linings and other passenger comforts such as multiple toilets (there is only one), meaning it is 6803-9071kg lighter than it otherwise would be, giving it a longer range and better performance. For the demonstration flight, we flew from Avalon Airport to the coast of Tasmania. This was to demonstrate high data rate “Resilient Beyond Visual Line of Sight Communications” (BVLOS) Australia's electronics magazine through Honeywell and Inmarsat’s SATCOM systems and software. The systems and software they demonstrated include JetWave MCX, HSD 400, Aspire 400 and the GoDirect Router, among others. These technologies allow communication from civilian or military aircraft anywhere in the world. As an example of the advantages, a recent RAAF disaster relief flight to a Pacific nation was diverted mid-flight to take still and video footage of the disaster which could immediately be uploaded via satellite and conveyed to Canberra for damage assessment and May 2023  25 decision-making. This avoided the expense of sending a second aircraft, which would have had to fly back to Australia to deliver the footage. JetWave MCX is a Ka-band (26.540GHz) SATCOM terminal product optimised for military communications and is now certified on the WGS satellite network (described earlier). Apart from WGS, Jetwave MCX allows connectivity via Inmarsat’s Global Xpress (GX) general-use network and High-Capacity Cross Strap (HCX) military Ka beams and other Ka-band networks. GX provides uplink speeds from the aircraft of 3Mbps and downlink speeds to the aircraft of 37Mbps. HCX military provides 100Mbps+ return speeds. Honeywell’s HSD-400 is a voice and high-speed data transceiver for the Inmarsat satellite network. It provides for Inmarsat SBB (SwiftBroadband) on L Band (1-2GHz) SATCOM and a Single Carrier Per Channel (SPCP) modem for L-Max capability. L-Max is an Inmarsat product that is between SwiftBroadband and Global Express in speed and on leased beams, operating on L Band. SBB provides speeds up to 1.7Mbps, while L-Max provides uplink and downlink speeds of 1.9Mbps. It is suitable for Intelligence, Surveillance, and Reconnaissance (ISR) Operations. The Aspire 350 is for cockpit satcom and uses Iridium Certus services on the Iridium NEXT constellation and provides 100% coverage of the Earth’s surface. It supports cockpit voice, Future Air Navigation System (FANS), Air Traffic Control (ATC), Aircraft Communication Addressing and Reporting System (ACARS), Aeronautical operational control (AOC) and Electronic Flight Bag (EFB). A data rate of 700kbps is supported, optionally increased to 1.4Mbps. The Aspire 400 uses SwiftBroadband, supports ACARS, AOC and EFB and has data rates of 2×432kbps with worldwide coverage between the poles. Significant weight reductions are achieved, and the need for HF comms is reduced or eliminated. The above equipment also requires appropriate antennas mounted on top of the fuselage. The GoDirect Router is a router that also holds Honeywell’s enterprise management and console software, allowing passengers to send and receive emails, participate in video conferences and surf the web. For more information, see the video titled “A Look At Honeywell’s Bizarre Boeing 757 Flight Test Aircraft” at https://youtu.be/ZjTPtBplz3U IAI early-warning radar Israel Aircraft Industries (www.iai. co.il) presented their ELM-2090UUltra early warning UHF radar family (Fig.21). It is transportable and designed to autonomously detect and simultaneously track dozens of ballistic missiles, satellites and airborne targets at very long ranges, including targets with low radar cross-section. It also provides launch location and point of impact estimates. The design is modular, so additional radar modules can be added as required. See the video titled “ELTAELM-2090U - ULTRA Early Warning UHF Digital Radar Family” at https:// youtu.be/xho-E5IM0MU Iron Beam and Lite Beam Israeli defence contractor Rafael presented Iron Beam and Lite Beam; see Fig.22 and www.rafael.co.il/worlds/ land/iron-beam/ Fig.22: Iron Beam’s steerable laser beam head, used to shoot down hostile drones and munitions. Source: www. rafael.co.il/worlds/land/iron-beam/ Iron Beam is a 100kW laser defensive weapon that is still under development and is expected to become operational within a year or two. It is designed to shoot down a wide range of threats, such as mortar shells, rockets, RAMs (rolling airframe missiles) and UAVs (unmanned aerial vehicles) or similar devices. It would be deployed as part of a multi-tiered defensive array, with Iron Beam intended for close interceptions, from a few hundred metres to several kilometres. Lite Beam, as the name implies, is a lower-powered 7.5kW version of Iron Beam, suitable for C-mUAVs (counter micro unmanned aerial vehicles), destroying weaponised balloons, improvised explosive devices or unexploded ordnance or similar at ranges of a few hundred metres to two kilometres. Lite Beam is at a “proven prototype” stage of development. Like Iron Beam, it forms an element of a multi-tiered defensive array. Rafael will also supply its Spike missile for use on the new Australian IFV, the Redback (if Redback is chosen – see below). You can refer to the video titled “Rafael’s Spike ATGM family – the Technological Answer to Superior Mass” at https://youtu.be/ dFbrzUfbFyw Kaman Kargo UAV Fig.21: an IAI ELM-2090U-Ultra early warning UHF radar that can warn of incoming rockets, artillery shells, drones and so on. 26 Silicon Chip Australia's electronics magazine Kaman makes Kargo UAVs (see Fig.23 & https://kaman.com/brands/ kaman-air-vehicles/kargo/) for transporting loads up to 363kg internally or externally. It can: • hover with a 215kg payload for 2.2 hours • hover with a 22.7kg payload for 4.7 hours siliconchip.com.au Fig.23 (above): the Kaman Kargo UAV can transport a 272kg payload 143nmi in 1.2 hours. Source: https://kaman.com/brands/ kaman-air-vehicles/kargo/ Fig.24 (right): the Australian Kite drone from Swoop Aero can take off and land vertically but flies like a traditional plane in the cruise portion of the flight – note the wings and two pusher propellers at the back, plus eight lift rotors on booms. • transport a 272kg payload 143nmi in 1.2 hours • transport a 136kg payload 326nmi in 2.7 hours • transport a 91kg payload 400nmi in 3.3 hours • travel 523 nautical miles with an external fuel tank in 4.3 hours The Kargo is powered by a 224kW gas turbine engine. For further information, see the video “KARGO UAV | Transforming Expeditionary Logistics” – https://youtu.be/datQouRo_fY Kite Kite is an Australian drone from Swoop Aero (see Fig.24) with vertical take-off & landing, and horizontal flight capability. It can operate in roles such as search & rescue, live video streaming, mapping and package delivery. It can carry a payload up to 250 × 205 × 125mm for 80km (6kg), 125km (4.6kg), 175km (3kg) or 225km (1kg). Its maximum take-off weight is 24.9kg, cruise speed is 122km/h and top speed is 200km/h. The company states that the system has been used to Fig.25: a Kite KM-120 electric motor, a roll of nanocrystalline core material, and a 9V battery for comparison. Source: https://kitemagnetics.com/ electric-motors/products siliconchip.com.au deliver 1.4 million items over 24,000 flights. It has been used extensively for humanitarian causes in Africa, where residents have been taught to use and maintain it. It is easy to maintain and can be recharged via a charger unit plugged into a generator. Kite Magnetics Kite Magnetics is a spin-off from Monash University (kitemagnetics. com/). In conjunction with the Monash Department of Materials Science and Engineering, they have developed highly efficient electric motors for small electric aircraft that utilise a nanocrystalline ferromagnetic soft magnetic alloy that reduces core losses in the motor. The alloy is branded Aeroperm. Kite has developed what they say is the world’s most powerful air-cooled electric aviation motor and the world’s first nanocrystalline, the KM-120, with a power output of 120kW (see Fig.25). room for them to be housed inside the aircraft, they must go on a wing or body mounted pod. Australian company Airspeed Composites (airspeed. com.au/) has developed a low-drag pod suitable for housing equipment at supersonic speeds – see Fig.26. It attaches to an airframe via standard general-purpose MS3314 suspension lugs. The pod is radio transparent to 18GHz and has conduction cooling and submerged “NACA” cooling ducts for the electronics rack. Windows can be installed for cameras. Monash High Powered Rocketry (HPR) HPR (www.monashhpr.com) is a student team that has developed Project Aether. The Aether rocket (Fig.27) competed in the 30,000ft commercial-­ off-the-shelf (COTS) solid propulsion category of the 2022 Spaceport America Cup and the 2020 Virtual Australian Universities Rocket Competition. Low Drag Electronics Pod Monash Nova Rover When developing sensors and other equipment for aircraft, if there isn’t The Nova Rover (www.novarover. space) is a student team from Monash Fig.26: a low-drag electronics pod containing a camera from Airspeed Composites. Source: https://airspeed. com.au/aerospace-2/ Fig.27: Monash’s HPR Aether rocket being launched. Source: www. monashhpr.com/rockets Australia's electronics magazine May 2023  27 Fig.28 (left): the Pegasus E flying car is being touted as a possible police vehicle. Fig.29: the two remaining finalists in the competition for a new Australian IFV, the Redback (left) and Lynx (right), to replace our ageing M113 APCs. Fig.30 (right): the Human Aerospace IVA Skinsuit, designed in conjunction with RMIT, is intended to prevent the deterioration of bones and muscles in space. It was tested on the International Space Station. University “designing, fabricating, and testing the next generation of Mars rovers right here in Melbourne – and inspiring future generations along the way”. See the video titled “Monash Nova Rover Team | 2022 University Rover Challenge SAR” at https://youtu. be/few9ZminRlg Pegasus Flying Car A practical flying car has long been a dream, but that might soon be a reality thanks to Melbourne-based, Australian-­owned company Pegasus (https://bepegasus.com/). Their product is described as the world’s only true flying car and it is designed to fit in a standard suburban garage or car space. No take-off area is required at your home because you would drive to a suitable take-off area. It uses an electric drive system on the road and an internal combustion engine and rotor blades for flight. It takes off and lands like a helicopter. For the Pegasus E (Fig.28), the electronically-limited road speed is 120km/h with a 70-75km range. The maximum flight speed is 160km/h, and the cruise speed is 130km/h with a range of 420km. In the event of a loss of engine power during flight, the Pegasus can auto-­ rotate to a safe landing. The vehicle’s dry weight is 265kg, and its payload is up to 101kg. The price is said to be comparable to a ‘supercar’. 28 Silicon Chip They are in the process of applying for VicRoads registration, and the Pegasus E has received an airworthiness certification as an experimental aircraft by CASA. A four-seat air taxi prototype will be released later this year. For more detail, see the videos titled “Pegasus, world’s first police flying car” at https://youtu.be/xbp0qkPQtjE and “Pegasus E flying car new flight! June 2022” at https://youtu.be/mwGz4-_QeQ Redback and Lynx LAND 400 is an Australian DoD program to replace our Army’s 1960s-era M113 armoured personnel carriers (APCs). Even though they have been upgraded in recent years to become M113AS4s, their armour is not protective against large improvised explosive devices and other modern threats, and they are regarded as obsolete. The LAND 400 project is a competitive process and has been reduced to two contenders, the Hanwha Defense Australia (parent South Korea) AS21 Redback and the Rheinmetall Defence Australia (parent Germany) Lynx KF41 – see Fig.29. These are infantry fighting vehicles (IFVs) rather than APCs, meaning they not only carry soldiers but can also fight alongside dismounted infantry. As a result, these new vehicles weigh considerably more than the M113AS4 APCs, which weigh 18t. The Redback Australia's electronics magazine weighs 42t and the Lynx 45t. Both carry three crew plus eight soldiers, less than the M113AS4, which carries two crew and about 10 soldiers. Saber Astronautics While not having a stand at the Airshow, Saber Astronautics (https:// saberastro.com/) is a company based in Australia and the USA that supplies Australian Defence and the Australian Space Agency. Defence Space Command uses Saber software, and they are involved in other aspects of the Australian space program. Sensorimotor Countermeasure Skinsuit The Human Aerospace IVA Skinsuit (www.humanaerospace.com.au; see Fig.30) was designed in conjunction with RMIT University and is for use by astronauts on orbital missions. It is designed to provide compression loading to parts of the body to simulate gravity, preventing the deterioration of bones and other parts of the body due to the lack of gravity. The Skinsuit has been tested on the International Space Station. Shotover If you’ve seen police car chase videos from overseas shown on TV, you might notice they have detailed street map overlays and other information on the video feed. That can be done siliconchip.com.au Fig.31: an example of a street map overlay over a car chase by the ARS-750, intended to aid police by showing what’s around a suspect during a ‘manhunt’. Source: https://shotover.com/products/ars by the ARS-750 Augmented Reality Solution from US firm Shotover – see Fig.31 (https://shotover.com/). downlink. It connects to the aircraft via standard NATO lugs. For civilian S&R, it can also be used with a Learjet 35. SiNAB Skykraft SiNAB (www.sinab.com) is an Australian company that has developed a JTAC training pod (see Fig.32) for use by the Air Force. JTAC stands for Joint Terminal Attack Controller, which Wikipedia writes is “a qualified service member who directs the action of military aircraft engaged in close air support and other offensive air operations from a forward position”. The pod contains various optical sensors and is called Phoenix (aka PJTS or Phoenix JTAC Training Solution). It enables the use of lower-cost training aircraft such as the Pilatus PC-9/A and Hawk-127 to emulate the air support capability of aircraft such as the F/A-18A/B for training purposes. Its optical sensors also make the system suitable for use in civilian search-and-rescue operations. The pod has a wireless cockpit interface and ground station for video On the 4th of January 2023, five Australian-made Skykraft satellites (see Fig.33) were launched into orbit, a total mass of 300kg, which the company says exceeds the “total mass of all Australian-built space objects ever launched”. Skykraft (www.skykraft.com.au) plans to launch 200 such satellites over the next two years, to provide a global air traffic management service with service in areas where there are now communications gaps, such as over the mid-ocean. Air traffic controllers will be able to track aircraft wherever they are and speak to pilots (see Fig.34). Current air traffic management systems only track aircraft within 400km of land. The satellites will track the aircraft’s ADS-B signal (Automatic Dependent Surveillance–Broadcast) and provide VHF voice and data Fig.32: the PJTS system attached to a Vietnam War-era Cessna O-2 Skymaster. It can be used for search and rescue missions or training. communications between air traffic controllers and aircraft. We published articles on ADS-B in the August 2013 issue – see siliconchip.au/Article/4204 SLM Solutions SLM Solutions (www.slm-solutions. com) presented their range of industrial 3D (additive manufacturing) laser printers to print complex metal shapes (see Fig.35). SNC Balloons have been in the news lately! Sierra Nevada Corporation (SNC; www.sncorp.com) presented their Lighter-Than-Air High Altitude Platform Station (LTA-HAPS) at the Airshow; see Fig.36. This balloon system comprises a lift balloon (with helium or cheaper hydrogen), a ballast balloon with air to adjust buoyancy to change altitude, solar arrays and a gondola that contains avionics and other equipment. That includes payloads for electronic warfare, surveillance, communications, cyber intelligence (“data Fig.34 (left): an aircraft flying far out over the sea can communicate with landbased traffic controllers via a Skykraft satellite while also being tracked. Source: Skykraft Fig.33: an artist’s concept of Skykraft satellites in orbit. They intend to provide global coverage for air traffic controllers, tracking aircraft and communicating with them. Source: Skykraft siliconchip.com.au Fig.35 (right): a complicated metal shape made with an SLM 3D printer. Its internal structure is much like a bone, providing high rigidity with low weight. Australia's electronics magazine May 2023  29 Fig.36 (above): the SNC LTA-HAPS balloon. From top to bottom, the components are the lift balloon, ballast balloon, solar panels and gondola with payload. Fig.38: the BAE/Innovaero Strix UAS can conduct strikes against ground or sea targets and persistent intelligence, surveillance & reconnaissance (ISR). It can carry a payload of up to 160kg for 800km and folds for easy transport. Fig.37 (right): the SpIRIT 6U nanosatellite carries an advanced gamma and X-ray sensor plus the Neumann Space Thruster, a highefficiency electric thruster. that is collected, processed, and analysed to understand a threat actor’s motives, targets, and attack behaviors”) and AI, among others. It is designed for long-persistence ISR (intelligence, surveillance, reconnaissance) missions of 60 days or more at up to 75,000ft (22.9km) altitude. It has a 50kg lift capacity and is difficult to detect. The balloon system uses polyethylene and latex in its construction and can be navigated by altering its altitude to merge with winds going in the desired direction. Southern Launch facilities Southern Launch offers two commercial rocket launch facilities in Australia (www.southernlaunch. space): the Koonibba Test Range and the Whalers Way Orbital Launch Complex (see Fig.40). The Koonibba Test Range offers over 10,000km2 of range area, up to 350km downrange and overland payload recovery. As the name implies, this is for test flights such as hypersonic vehicles. The Whalers Way Orbital Launch Complex is at the tip of the Eyre Peninsula in South Australia. It offers a launch facility for suborbital flights along Australia’s southern coastline (eg, to Albany, WA) or launches into Sun-synchronous or polar orbits. SpIRIT 6U nanosatellite The SpIRIT (Space Industry Responsive Intelligent Thermal) nanosatellite (https://spirit.research.unimelb.edu. au/) is an Australian-made spacecraft but an Italian-Australian cooperative project. The spacecraft is launched as a 6U CubeSat form factor nanosatellite, 30 × 20 × 10cm and weighing 11.5kg, which later unfolds – see Fig.37. Its primary science payload is for advanced gamma and X-ray remote sensing – the HERMES instrument, developed with funding by the Italian Space Agency and the European Commission H2020 framework. The Australian-made equipment includes: • The Neumann Space Thruster, a high-efficiency electric propulsion unit for applications in lunar orbit and beyond Earth • The University of Melbourne Thermal Management Integrated System (TheMIS) for precision temperature control of sensitive instrumentation • The University of Melbourne Mercury module for adaptive autonomous low-latency communications • The University of Melbourne Payload Management System, designed to facilitate integration and control of complex instrumentation in off-theshelf satellite platforms and to perform data processing Strix Uncrewed Aerial System BAE Systems Australia and Perthbased Innovaero are developing the futuristic-looking Strix Uncrewed Aerial System (www.baesystems.com/ en-aus/strix). The tandem-wing autonomous aircraft (see Fig.38) was launched at the Airshow. It is designed for various missions, including strikes against ground or sea targets and persistent Fig.40: preparing for a launch at Whalers Way Orbital Launch Complex. Source: www.southernlaunch.space/whalers-wayorbital-launch-complex Fig.41: the SX1-ISR, a solar-powered long-range UAV by XSun. It can cruise at 50-70km/h for up to nine hours with silicon solar cells or 12 hours with GaAs cells, with additional endurance provided by a battery. 30 Silicon Chip Australia's electronics magazine siliconchip.com.au Fig.39: the Swinburne hydrogen-powered drone. intelligence, surveillance and reconnaissance (ISR). It can carry a payload of up to 160kg for 800km and folds for easy transport. of hydrogen propulsion in aviation – see Fig.39 & siliconchip.au/link/abkf SX1-ISR The SX1-ISR is a solar-powered long-range UAV by XSun (www.xsun. Supashock (https://supashock.com/ fr). It has dual wings with solar panen/) is an Australian company self-­ els, two propellers, and can cruise at described as “a world-class producer of 50-70km/h with a maximum speed of advanced mobility, advanced logistics 110km/h. Its endurance is up to nine handling systems and advanced auton- hours with silicon solar cells or 12 omous systems that control, moni- hours with GaAs cells, with additional tor and improve mobility of Defence, endurance provided by a battery. Autonomous, commercial, automotive It can carry a payload of up to 5kg, and other transport vehicles”. such as a gimballed thermal or visible One of the products they had on light camera. Live video can be transdisplay was a hydraulic damper for mitted up to 100km via line-of-sight on the proposed Lynx Infantry Fighting a 2.4GHz link frequency – see Fig.41. Vehicle for the Australian Army. See the video titled “Rheinmetall – Lynx RAAF bomb disposal robots KF41 IFV for Australia Unveiled” at The RAAF, No.65 Squadron, responhttps://youtu.be/n5p_lrNw-EY sible for explosive ordnance disposal etc, displayed some of their ordnance Swinburne University disposal equipment. That included The Swinburne University of Tech- two robots, the Dragon Runner 20 from nology has developed thermal spray Quinetiq (Fig.42 & siliconchip.au/link/ technology to put specialised sur- abkg) and the Talon Tactical Robot faces on various substrates such as (siliconchip.au/link/abkh). implants. They have also produced a hydrogen-­ Vertiia powered drone to test the feasibility AMSL Aero (www.vertiia.com) is Supashock Fig.42: the Dragon Runner 20 robot is used for defusing or detonating bombs. siliconchip.com.au an Australian company that has developed a long-range eVTOL aircraft called Vertiia (see Fig.43). According to the manufacturer, it is powered by hydrogen, has a range of 1000km, a speed of 300km/h with five seats or 500kg of cargo and operating costs 75% less than a helicopter. It will travel 250km on battery power alone. Other Universities More universities than those mentioned above were at the Airshow, offering aerospace courses, including: • Curtin University Space Science and Technology Centre (https://sstc. curtin.edu.au/). • Deakin University (www.deakin. edu.au). • Monash University (www. monash.edu). • RMIT University (siliconchip.au/ link/abku). • Swinburne University Space Technology Institute (siliconchip.au/ link/abkv). Editor’s note: the Airshow had other events on, such as a flare drop being performed by a RAAF C130, see www. SC jetphotos.com/photo/10900297 Fig.43: the Australian-developed Vertiia eVTOL aircraft can carry five people or 500kg of cargo and travels up to 1000km or 250km on batteries alone at up to 300km/h. Source: Vertiia – siliconchip.au/link/abkz Australia's electronics magazine May 2023  31 Dual RF Amplifier for Signal generators This small RF amplifier has two outputs with individually selectable gains. This makes it suitable to add to a signal generator to provide a higher output level, or for better drive strength, or ‘fanning it out’ to multiple other pieces of equipment and more. by Charles Kosina any signal generators do not M provide a high enough output level for certain uses. This small PCB uses an OPA2677 high speed dual op-amp to boost signals of 100kHz75MHz at around 0dBm (1mW, 225mV/-13dBV into 50W) to around 18dBm (63mW, 1.78V/5dBV into 50W). The OPA2677 has impressive specifications. It can operate on voltages from 3.3V to 12V, has rail to rail outputs, a high drive capability and a gain bandwidth (GBW) of 200MHz. But what makes it stand out is a slew rate of 1800V/µs, which means it can provide a large output swing for high-­ frequency signals. Because it is a dual op amp, my design provides two outputs for the one input signal. Individual feedback resistors and a potentiometer set the gain for each output. The maximum gain is 1 + (470W ÷ 68W) = 7.9 times with the 1kW single-­ turn trimpot set to minimum. The lowest gain is 1 + (470W ÷ 1068W) = 1.44 times with the trimpot set to maximum. The output impedance is 50W and it will safely drive a 50W load. The power supply voltage should ideally be in the range of 9-12V. You could use 5V DC, but the amplified signals will be limited to 5V peak-to-peak at the op amp output and 2.5V peak-topeak at the 50W load, or 884mV RMS (13.9dBm/24mW). The maximum output with a 12V supply is about 25dBm, as shown in the specifications panel. The Amplifier is useful from 100kHz to 75MHz, although once past 50MHz, the maximum output level starts to drop off. Table 1 shows spot measurements at several frequencies using my signal generator as an input. The output variability somewhat depends on the signal generator variation in output level. The OPA2677 is not cheap, about $9 from Digi-Key, Mouser or element14, but I bought five from AliExpress for $14.50. Still, even if you pay $9, the overall cost of building this Amplifier Features and Specifications ∎ Operating frequency range: 100kHz to 75MHz ∎ Number of inputs: 1 ∎ Number of outputs: 2, individually gain adjustable ∎ Gain range: 1.44 times (3dB) to 7.9 times (18dB) ∎ Maximum output level: 25.6dBm <at> 30MHz (360mW into 50Ω, 12.5dBV, 4.25V RMS) 23.2dBm <at> 50MHz (207mW into 50Ω, 10dBV, 3.2V RMS) 13.5dBm <at> 70MHz (22mW into 50Ω, 0.51dBV, 1.06V RMS) ∎ Power supply: 9-12V DC <at> 20-25mA (or 5V DC with reduced maximum output levels) 32 Silicon Chip Australia's electronics magazine is modest. See the panel at the end of the article on the short-form kit. Circuit description The whole circuit is shown in Fig.1. The signal fed in via SMA connector CON1 is AC-coupled to both halves of dual op amp IC1 via 100nF capacitors. These signals are biased to half the VCC rail (eg, 2.5V for a 5V supply or 6V for a 12V supply) using 470W resistors. Those coupling capacitors and bias resistors form high-pass filters with a corner frequency of 3.4kHz (1 ÷ [2π × 100nF × 470W]) so they will not attenuate signals within the specified operating frequency range, from 100kHz to 75MHz. The signals are coupled to the non-inverting input pins, so the amplifiers do not invert the signal phase. The outputs of the op amps (pins 1 & 7) are fed back to the inverting inputs (pins 2 & 6) via 470W resistors, which form voltage dividers with trimpots VR1/ VR2 and their series 68W resistors. The 100nF capacitors in the feedback network reduce the DC gain of these amplifiers to 1x so that the input offset voltages (up to 5.3mV) are not amplified. The corner frequency of the high-pass filter formed is similar to that of the input networks as the component values are the same. As mentioned earlier, the op amps have very high gain bandwidths (GBW) and slew rates, so they are effective up to high frequencies. Because the gain bandwidth is fixed, the maximum signal frequency drops as you increase the gain. For example, with siliconchip.com.au the GBW of 200MHz, a gain of four times is possible at 50MHz or about three times at 70MHz. The outputs of the two op amps are coupled to SMA connectors via 100nF capacitors to eliminate the VCC/2 DC bias and fed through 51W resistors for impedance matching. You could change them to 75W if you need to feed into a 75W device. The VCC/2 rail is formed by a simple 1.2kW/1.2kW voltage divider with a 100nF capacitor from the junction to ground to eliminate supply ripple and keep the source impedance low at higher frequencies. Op amp IC1 also has the obligatory 100nF supply bypass capacitor. Note that there is no termination resistor for input CON1. You could add an M2012/0805 size resistor (51W or 75W) across the terminals of the SMA socket if you need one. Construction Construction is relatively straightforward as there are only a couple dozen components total. The Dual RF Amp is built on a double-sided PCB coded CSE220602A that measures 38 × 38mm. Refer to the PCB overlay diagrams, Figs.2 & 3, to guide you during assembly. Start by fitting the SMDs to the component side, with IC1 first. Determine its pin 1 location – look for a dot or divot in one corner, or failing that, a chamfered edge on the pin 1 side. Table 1 – frequency vs maximum output level <at> 12V DC Frequency Output (p-p) Output (RMS) Output (dBm) Output (dBV) 1MHz 9.5V 3.36V 23.5 10.5 10MHz 8.4V 2.97V 22.5 9.5 20MHz 10.0V 3.54V 24.0 11.0 30MHz 12.0V 4.24V 25.6 12.5 40MHz 9.6V 3.39V 23.6 10.6 50MHz 9.1V 3.22V 23.2 10.2 60MHz 5.6V 1.98V 18.9 5.9 70MHz 3.0V 1.06V 13.5 0.51 Locate it with pin 1 towards the upper right with the PCB orientated as shown in Fig.2. Add flux paste to its pads, then tack one pin with a bit of solder and check the alignment of the other pins. If they are good, solder the diagonally opposite pin. Otherwise, heat the original solder joint and gently nudge the part until it is in place. Then solder the remaining pins, refresh the first one and clean up any solder bridges which might have formed between pins with another dab of flux paste and some solder wick. Clean flux residue off the board with alcohol or a flux cleaner and inspect the solder joints to ensure they are all good. Then proceed to fit the passives, none of which are polarised, using a similar technique of tacking one side, then adjusting the alignment and after a brief delay to allow the solder to solidify, solder the other side. Fig.1: the Dual RF Amp is a straightforward implementation of the OPA2677 dual high-bandwidth op amp. Signals are AC-coupled at the inputs and outputs so they can be DC-biased to a half supply rail formed by two resistors and a capacitor. Trimpots VR1 & VR2 adjust the feedback ratio and thus the gain of each individual amplifier. siliconchip.com.au Australia's electronics magazine The resistors will be marked with codes indicating their values (eg, 122 or 1201 for 1.2kW), while the capacitors will not be marked, but they are all the same value (100nF). When all the SMDs are mounted on that side, flip the board over and solder the lone capacitor on the other side. That just leaves the six through-hole components: two trimpots, the power header and the three SMA sockets. It’s best to fit the SMA sockets next, so you have good access to their pins. Push them down fully and solder all five pins, keeping in mind that you may need some extra heat or flux to solder the four outer pins due to their thermal mass. Finally, mount the two trimpots and the power header. Use single-turn trimpots as multi-turn types likely have too much inductance. You could Figs.2 & 3: most components are SMDs that mount on the rear, while one capacitor and the three SMA connectors are on the front. The RF connector side of the board is covered with a ground plane. May 2023  33 solder some figure-8 wire directly to the board for power, but a polarised header is more convenient. Its exact orientation doesn’t matter as long as you observe the + and – markings when wiring it up. Housing it As the board is small, it can fit into most cases. A metal case is preferred for RF shielding. See the parts list for suggestions and note that the 51 × 51mm diecast cases sold by Jaycar and Altronics are too small to fit the PCB. Fig.4 shows the hole positions to drill in the lid or base, and the board can then be mounted using the SMA connector nuts. Drill a hole in the side of the case to fit a chassis-mount barrel socket and wire it up to CON4. Double-check that the positive wire (usually the tip of the barrel socket) goes to the + side of CON4, as the board has no reverse polarity protection. There isn’t a great need for a power switch as you can simply unplug the plugpack from the wall when you aren’t using it. Still, if you want to add a power switch, all you have to do is drill a hole in a convenient location, mount the power switch and wire it in series with the positive conductor from the barrel socket to CON4. If you want to add reverse polarity protection, solder a 1N5819 diode to the barrel socket with its anode to the positive tab of the socket, then run the supply wire to the board or switch from its cathode. That will drop the supply voltage slightly, by around Parts List – Dual RF Amplifier 1 double-sided PCB coded CSE220602A, 38 × 38mm 1 diecast aluminium case, large enough to fit the PCB [eg, Jaycar HB5062, 111 × 60 × 30mm] 1 9-12V DC 50mA+ plugpack or other DC supply 1 OPA2677IDDA dual high-bandwidth op amp, SOIC-8 [element14, Mouser, Digi-Key] 2 1kW single-turn 3362P-style top adjust trimpots (VR1, VR2) 8 100nF 50V X7R SMD ceramic capacitors, M2012/0805 size 3 vertical SMA female sockets (CON1-CON3) 1 2-pin polarised header with matching plug and pins (CON4) 1 chassis-mount DC socket to suit plugpack plug 1 short length of light-duty figure-8 cable 1 chassis-mounting SPDT switch (optional; power switch) 1 1N5819 schottky diode (optional; see text) Resistors 2 1.2kW 4 470W 2 68W 2 51W 0.3V, so it may have a small impact on the maximum output signal level. Finally, you might want to drill a couple of small holes in the face of the case opposite the board so that you can slot in a thin adjustment tool to adjust trimpots VR1 and VR2 with the case closed. That depends on your application; you could just set a different fixed gain for both trimpots and then use whichever output suits your needs at the time. Before screwing on the lid, unplug the CON4 plug from the board, connect your power supply to the barrel socket and use a DMM to check that the power polarity at the plug is correct. Then plug it in and connect a signal to the input socket. Verify that an amplified version of the signals appears at the outputs using a scope, signal level meter or frequency counter, depending on what you have on hand. Using it There isn’t much to it – just power it up, feed in your signal, adjust the level using trimpot VR1 or VR2 if necessary, and take the output from the corresponding socket. The CON2 signal level/gain is adjusted using VR1, and the CON3 signal level/gain is adjusted using VR2. Keep in mind that VR1 and VR2 are wired such that anti-clockwise rotation increases the gain and clockwise rotation decreases it. This article is in memory of Rod Graham, VK3BQJ, who passed away SC on November 4th 2022. SC6592 Kit ($25 + P&P) Includes the PCB and all onboard parts. You only need to add a case, DC socket, wiring and the optional power switch. Fig.4: just about any metal case would be suitable but this one is relatively compact. The lid is larger than the base, so if using this as a template, cut it to the appropriate outline. The central area could be cut out and transferred to just about any other case. The hole in the side for the power socket is not shown here; it could go just about anywhere. 34 Silicon Chip Australia's electronics magazine Compared to the lead image, which is shown enlarged, here is the finished Dual RF Amplifier shown at life size. siliconchip.com.au The Staff Picks ay Sale prices must end M 60 65 $ 31st. X 4204 3+12 Dioptre A 2696A X 4205 5 Dioptre SAVE $26 99 $ 349 $ STA F F Internet radio, digital radio & audio streaming in one. STA F ! to eye strain Say goodbye $ T 2690A SAVE $40 SAVE $15 Why pay $300 for a MaggyLamp? The inspect-a-gadget illuminated desk magnifier is an absolute bargain at under $70, we believe ours is every bit as useful. An incredible visual aid for detailed inspection and work on fine items with full clarity through the quality glass lens. Tackle complex miniature tasks with confidence! 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STA F F SAVE $120 PICK SAVE $70 C 0876A 479 $ Supports multi-cast for up to 4 receivers! 349/pr $ SAVE $10 SAVE $20 39 85 $ Opus One® Bluetooth® Ceiling Speakers Built to stream the best content from your favourite music streaming service, app or podcast player. Bluetooth 5.0 technology offers superb audio performance and range. In-built high performance 2x30W RMS amplifier. The ideal way to add permanent wireless sound to any room in the house. A modern, low profile finish is provided by frameless magnetic fit grilles. Includes power supply. Sold in pairs. SAVE $61 99 $ P 7334B 5m A 3605 $ P 7336B 10m P 7338B 15m Send HDMI signals wirelessly! Bargain Flat HDMI Cables! HDMI V2.0 cables with aluminium connectors and flat cable sheath (18x3.5mm) for running behind equipment and under carpets, furniture etc. Designed to send a 4K 60Hz HDMI signals, plus infra-red remote signals wirelessly up to 150m line of sight. Supports stereo audio (44Khz). Includes power supplies, HDMI cables and IR emitter cable. Low 100ms latency. Note: distance can be restricted by number of walls between transmitter and receiver. i12 Bluetooth® Earbuds STA F F PICK These affordable wireless Bluetooth 5.0 earbuds offer great sound for less! 2-3 hour listening time per charge. Compatible SAVE 25% with iOS & Android devices. 22 $ 4 Channel USB Mixer With Equaliser & FX Want to get into recording podcasts, voice overs or making your own audio samples? This mini USB mixer connects directly to your PC or Mac and is powered directly from USB. Includes 3 band EQ and effects. A 2548 C 9032A SAVE 40% 30 $ C 9044 Listen while you walk, run or ride! SAVE 20% 39 40 $ $ Flexible Sports Headphones • Bluetooth 5.0 for great range and audio quality. • Great sound and amazing 16 hour battery life • Super comfortable & compact design SAVE 25% SAVE $30 22 Top Value Wireless Earbuds Bluetooth Plane Adaptor Bluetooth 5.0. Sweat resistant design great for exercise. 3-4hrs of listening time C 9037B with battery bank case. Transmits audio from any single or dual jack airplane audio socket to your favourite Bluetooth headphones. 4-5 hours listening. D 0984 $ 109 $ A 1111 SAVE 20% SAVE 33% 33 $ With muting button D 0985 SAVE $20 55 $ D 0982 3.5mm Lapel Mic Electret Lapel Mic USB Conference Microphone Ideal for audio recording on smartphones, laptops, vlogging cameras. 3.5mm TRRS or TRS connection. 2m lead. Condenser type. Need to record high quality audio for YouTube or live demos? This 6m electret mic offers excellent audio clarity and 3.5mm TRRS or 6.35mm TS connections. Top quality audio for group communications or one-on-one meetings. USB C connection. Rugged diecast case with rubber feet for excellent isolation. Includes 2m USB cable. Order online at altronics.com.au | Sale pricing ends May 31st Last chance CLEARANCE. Creality® LD-002R Resin 3D Printer SAVE $400 Affordable entry level resin printer for fast, strong & smooth prints. SAVE $170 Resin based 3D printers are rapidly becoming the go to tool for high resolution 3D prints. They offer a faster print process with excellent accuracy and a stronger finished product thanks to UV curing on each layer. The LD-002R can print objects up to 120 x 65 x 165mm. It is capable of printing up 20-30mm per hour, making it much faster than traditional FDM 3D filament printers. 299 $ 9999 Count True RMS DMM Featuring a striking easy to read reverse backlit screen. Auto ranging with push button operation. Q 1090 70 M 8133 240V Mains Power - Anywhere, Anytime! Powerhouse® Inverter with in-built MPPT solar charge controller. Provides you with 1500W of continuous pure sine wave mains power, plus the ability to recharge your batteries via connected solar panels. In-built maximum power point trackin (MPPT) circuitry ensures maximum charge from your panels. Ideal for caravans, RVs and boats - or anywhere you need remote 240V power! K 8620 Audio Signal Generator $ Q 1542 88 $ A 0319 80 $ 50 $ M 8990A Wireless Global Travel Charger SAVE $47 Q 1255A A do-it-all USB power delivery charger (18W), Qi wireless charger and battery bank (6700mAh) for devices. Includes case. 40 Iroda® Butane Heat Gun SAVE $17.50 Ideal for checking ‘damp’ problems in your home 22 Digital Moisture Level Meter Dual Wireless Charging Pads Measures moisture levels in wood, concrete, plaster etc. Ideal for monitoring damp or moisture ingress. Requires 9V battery. Charge two phones at once with cable free wireless charging. Requires QC3.0 USB wall charger (such as M8863A $29.95). $ D 2327* 99 This unit includes mains lead and 10 tips to suit popular models of laptop. Auto voltage sensing, 5-24V <at> 90W max. HALF PRICE! Detects and analyses voltage, cold cranking amperes, resistance & cell condition in 12V lead acid cells. Ideal for vehicle servicing or checking 12V SLA cells in backup systems. A high output butane powered hot air gun with two nozzle attachments ideal for heatshrinking, paint removal and much more! 3hr run SAVE time. 550°C max. $36 $ Replacement Laptop Supply Battery Health Analyser SAVE 22% $ SAVE $25 SAVE $39 A useful pocket sized signal generator. Generates sine and square waveforms in 46 preset frequencies from 20Hz - 150kHz. SAVE 25% 499 $ 99 $ T 2498 Q 2120 Hundreds more clearance deals available online <at> altronics.com.au Western Australia Build It Yourself Electronics Centres Sale Ends May 31st 2023 Phone: 1300 797 007 Fax: 1300 789 777 Mail Orders: mailorder<at>altronics.com.au » Perth: 174 Roe St » Joondalup: 2/182 Winton Rd » Balcatta: 7/58 Erindale Rd » Cannington: 5/1326 Albany Hwy » Midland: 1/212 Gt Eastern Hwy » Myaree: 5A/116 N Lake Rd Victoria 08 9428 2188 08 9428 2166 08 9428 2167 08 9428 2168 08 9428 2169 08 9428 2170 » Springvale: 891 Princes Hwy » Airport West: 5 Dromana Ave 03 9549 2188 03 9549 2121 New South Wales » Auburn: 15 Short St 02 8748 5388 Queensland » Virginia: 1870 Sandgate Rd 07 3441 2810 South Australia » Prospect: 316 Main Nth Rd 08 8164 3466 Please Note: Resellers have to pay the cost of freight & insurance. Therefore the range of stocked products & prices charged by individual resellers may vary from our catalogue. © Altronics 2023. E&OE. Prices stated herein are only valid until date shown or until stocks run out. Prices include GST and exclude freight and insurance. See latest catalogue for freight rates. *All smartphone devices pictured in this catalogue are for illustration purposes only. Not included with product. B 0005 Find a local reseller at: altronics.com.au/storelocations/dealers/ Using Electronic Modules with Jim Rowe UVM-30A Module Ultraviolet Light Sensor This ultraviolet (UV) light-sensing ‘breakout’ module detects the intensity of UV solar radiation and hence the degree of protection you may need to prevent skin damage. If you connect it to an Arduino or other microcontroller, it can even indicate the current ‘UV Index’. P rotection is critical if you spend a lot of time outdoors during daylight hours (sunscreen, hat etc) to avoid sunburn and to lower your chances of developing skin cancer. The UVM-30A analog UV light sensing module is ideal for detecting harmful UV rays and can be used to build your own UV sensor. It easily connects to an Arduino or other microcontroller unit (MCU) and with the right firmware, it will indicate the current UV Index or ‘UVI’. If you’re unsure what this is, please see the “UV Radiation and the UV Index” panel. Sunburn and skin damage are caused by the UV wavelengths in solar radiation, which can still be quite strong even when the sky is overcast. So checking the UV radiation level is still important. UV radiation varies in strength during the day, just like visible light and infrared (IR) heat radiation. As with these other wavelengths, its intensity tends to follow a bell-shaped curve, with the peak at the middle of the day or soon thereafter. So it can be worthwhile to keep tabs on the UV radiation level if you are going to be outdoors, even in the early morning or late afternoon. At the heart of the UVM-30A module is a miniature UV sensor called the GUVA-S12SD. This is in an SMD package measuring 3.5 × 2.8 × 1.8mm and is made by Genicom Co Ltd in South Korea. Genicom describes it as a schottky-­ type gallium nitride photodiode designed to respond to UV radiation with wavelengths between 240 and 370nm (nanometres). It is also described as being ‘blind’ to visible light. The response curve of the GUVAS12SD sensor is shown in Fig.1. Its sensitivity is very low at wavelengths below 240nm, rising steadily to a peak at 350nm before dropping sharply between 360nm and around 375nm. So it has good sensitivity over the UV-B range from 280nm to 315nm and even better sensitivity over slightly more than half of the UV-A range, from 315nm to 365nm. The vertical units in Fig.1 are microamps per milliwatt of UV radiation. The Genicom data sheet for the GUVAS12SD lists the typical peak response of the device as 0.14A/W at 350nm, equivalent to the peak of the curve in Fig.1. The UVM30A module is comprised of a larger PCB (28 × 12.5mm) and a smaller PCB (3.5 × 2.8mm). The smaller PCB hosts the GUVA-S12SD UV sensor in a white SMD package. Fig.1: the sensitivity of the GUVA-S12SD sensor to light within the UV spectrum. The x-axis is the light wavelength in nanometres, while the y-axis shows the microamps conducted per milliwatt of incident radiation at that wavelength. This indicates that it’s most sensitive to UV-A but will also pick up much of the UV-B spectrum and some UV-C, at reduced sensitivity. siliconchip.com.au Australia's electronics magazine This image is shown at 250% actual size. May 2023  43 Inside the module Fig.2: the circuit of the UV sensor module is pretty straightforward. A bias voltage is applied to the photodiode from the op amp output via a resistor, converting the current into a voltage that’s fed to the OUT pin. The yellow box surrounds the components on the sub-PCB; the main PCB just adds a bypass capacitor and the 3-pin SIL header with two power pins (+ and −) and the analog output. As shown in the circuit diagram, Fig.2, there’s very little in the UVM30A module apart from the GUVAS12SD sensor (PD1), and a small SGM8521 op amp (IC1) used to convert its output current into a voltage. The conversion performed by op amp IC1 conforms to the expression Vo = 4.3 × 106 × Ipd, where Ipd is the current passed by PD1 in amps. So a PD1 current of 280nA should result in an output of 1.2V. Most of the circuitry in Fig.2 is inside a pale yellow rectangle with a dashed red border because that part of the module is on a small subPCB mounted on the larger PCB. The smaller PCB measures only 3.5 × 2.7mm square, while the larger module PCB is 28 × 12.5mm. The only components on the larger PCB are a 10μF supply bypass capacitor and a 3-pin SIL header. Connecting it to an MCU Fig.3: wiring up the module to an Arduino Uno couldn’t be much simpler. Just connect the module’s + supply pin to its +5V, the module’s – supply pin to its GND and the module’s output to one of its analog inputs (in this case, A0, to suit our example sketch). Fig.4: connecting the UV sensor module to an Arduino Nano isn’t much different than the Uno shown in Fig.3. Once again, the module is supplied with 5V from the Nano’s +5V and GND pins while the module’s analog output signal goes to the Nano’s A0 analog input. 44 Silicon Chip Australia's electronics magazine Since the module has an analog voltage output and operates from a DC supply voltage of 3.3V to 5V, it is quite easy to connect to a microcontroller such as an Arduino Uno or Nano. You just need to connect the + and − power pins to the +5V and GND pins on the MCU board, while the “OUT” pin goes to an analog input on the MCU, such as the A0 analog input, as shown in Figs.3 & 4. All that’s needed then is suitable firmware. After searching the internet, I found a website with a graph showing the output voltage of the UVM30A module plotted against the equivalent UV Index (see siliconchip.au/link/ abi0). I’ve redrawn this as Fig.5. On the same website, I also found an Arduino sketch for a UVI sensor, although this sketch was designed to display the calculated UVI level using a Nokia 5110 LCD module. I adapted this sketch into one that displays both the module’s output voltage and the equivalent UVI figure on a low-cost 16×2 LCD module with an I2C serial interface (eg, Silicon Chip Online Shop Cat SC4198). Fig.6 shows how an Arduino Uno connects to both the UVM30A module and the LCD with the I2C interface attached. The resulting sketch file is called “Arduino_UVI_meter_sketch.ino” and is available for download from the Silicon Chip website. When you upload siliconchip.com.au Fig.5: the mapping of the output of the UV sensor to the UV index is primarily linear, except below a UV index of one. Therefore, the formula to convert its output voltage to the UV index is pretty simple. The sketch source code (available for download) shows exactly how it’s down. Shown at right is the Adafruit version of the UV sensor. It uses the same GUVA-S12SD sensor IC as the Altronics version. it to the Arduino, it first gives you this opening display: Silicon Chip UVI Meter Then, after pausing for two seconds, it starts measuring the output voltage from the UVM30A module. It converts the reading into the equivalent UV Index and displays both, like this: UV Index = 2 Vout = 350mV It repeats this every 1.5 seconds. The sketch also sends this data back to your computer via the Serial Monitor (if you have it connected). So it is easy to hook the UVM30A UV sensing module up to an MCU like the Arduino and make yourself a handy UVI meter. The sketch could also be adapted to MMBasic code for use on a Micromite or Maximite; any microcontroller with an analog input should do. One morning in late October, I took this arrangement outdoors and got UVI readings of 1-2 when the Sun was only about 30° above the horizon. The readings steadily rose as the morning wore on (although they dropped back when clouds obscured the Sun). When the Sun was directly overhead and the clouds were not obscuring it, the UVI readings reached a level of 8 or 9. So it appears to be doing its job and should be helpful for those who spend a lot of time outdoors. By the way, the Australian Bureau of Meteorology also publishes UV Index predictions in their forecasts. Of course, they only give a rough idea of what to expect, whereas this module provides a reading of the immediate conditions. Cost and availability I obtained the module shown in the photos from Altronics (catalog code Z6397) for around $40. But I also discovered a smaller version of the module available from several other suppliers. This version has the same circuit, but everything is mounted on a single PCB measuring only 19 × 10 × 2mm and seems to originate from the US firm Adafruit (www.adafruit.com). Adafruit has it (ID 1918) available for US$6.50 plus shipping. But it’s also available from Australian firms such as Pakronics (www.pakronics. com.au) for just under $15 plus shipping, or from Digi-Key in the USA for around the same price. There is yet another smaller version available from various suppliers on AliExpress. This one measures 19.8 × 10 × 2mm and is available for around $6 with free shipping. So you have quite a good range to choose from, all with the same UV sensor and its surrounding circuit, in various sizes and prices. continued on page 46 Fig.6: to make a practical device, I added a serial (I2C) 16×2 LCD module to the basic circuit, wired as shown here. That allows the Arduino to display both the raw UV sensor output voltage and the equivalent UV index in a handy portable package if the Arduino is battery-powered. siliconchip.com.au May 2023  45 UV Radiation and the UV Index Ultraviolet or UV radiation is electromagnetic radiation with wavelengths between 10nm (nanometres) and 400nm – shorter wavelengths than the light that is visible to humans but longer than the wavelength of X-rays. UV radiation constitutes about 10% of the total radiation from our Sun. Still, this radiation is the primary cause of suntan, sunburn and skin damage resulting in skin cancers. The section of the solar UV radiation spectrum primarily of interest regarding human skin safety is between 100nm and 400nm. This is subdivided into three main divisions: UV-A (315nm to 400nm; ‘long wave UV’), UV-B (280nm to 315nm; ‘medium wave UV’) and UV-C (100nm to 280nm; ‘short wave UV’). Although photons of UV-C radiation carry more energy than those of UV-B or UV-A and are therefore more capable of skin damage, the good news is that virtually none of the Sun’s UV-C radiation ever reaches the surface of the Earth. These photons are absorbed by oxygen and ozone in our upper atmosphere. Most of the UV-B radiation from the Sun suffers the same fate, especially when there is heavy cloud cover. When there is cloud cover, more than 95% of the solar UV radiation reaching the surface of the Earth consists of the longer UV-A wavelength. And these wavelengths are of concern when it comes to protecting our skin. So clouds tend to reduce the amount of UV reaching the surface but do not eliminate it; you can still get sunburn on a cloudy day. The UV Index is an international measurement scale used to indicate the intensity of UV radiation in easily understood terms for the ‘general public’. It uses a scale of 11 or more steps, with each step corresponding to an increase of UV radiation intensity of 25mW/m2 (milliwatts per square metre). A UVI of one indicates a UV intensity of 25mW/m2, two indicates an intensity of 50mW/m2 and so on. Fig.7 shows the UV Index on the right and the corresponding UV radiation intensity on the left. The coloured bands indicate the five categories into which the UVI levels are grouped in terms of their ‘risk of harm’ to our skin. SC Fig.7: this shows the five ranges of UV index values that provide some guidance as to the danger of skin exposure under those conditions. It will depend somewhat on your skin pigmentation, but it’s still a good idea to ‘cover up’ at the upper end of the risk spectrum. Raspberry Pi Pico W BackPack The new Raspberry Pi Pico W provides WiFi functionality, adding to the long list of features. This easy-to-build device includes a 3.5-inch touchscreen LCD and is programmable in BASIC, C or MicroPython, making it a good general-purpose controller. This kit comes with everything needed to build a Pico W BackPack module, including components for the optional microSD card, IR receiver and stereo audio output. $85 + Postage ∎ Complete Kit (SC6625) siliconchip.com.au/Shop/20/6625 The circuit and assembly instructions were published in the January 2023 issue: siliconchip.au/Article/15616 46 Silicon Chip Australia's electronics magazine siliconchip.com.au MEASURING EQUIPMENT PERTH SYDNEY BRISBANE MELBOURNE (03) 9212 4422 (08) 9373 9999 1/2 Windsor Rd, Northmead 625 Boundary Rd, Coopers Plains 4 Abbotts Rd, Dandenong 11 Valentine St, Kewdale (02) 9890 9111 (07) 3715 2200 Specifications are subject to change without notification. Established 1930 03_SC_270423 “MeasumaX, a new dimension in quality and value” ADM Instrument Engineering AFG* AIM Solder Australia AIM Training Alfatron Altronic Distributors Amtech* Arno Fuchs* Asscon* Chase Corporation Humiseal* Chemtools CNS Precision Assembly congatec Australia Control Devices Australia Curiosity Technology* Deutsch* Dinkle* Dyne Industries Electro Harmonix* element 14 Embedded Logic Solutions Emona Instruments Epson Singapore ETS-Lindgren* ESI Technology Ltd* Europlacer Eurotherm* Excelpoint Systems Faraday Flairmesh Technologies Fluke* Frankonia* F&S Bondtech* Fuseco Glyn Limited Green PCB GW Instek* GPC Electronics Hammond Manufacturing Harbuch Electronics Hawker Richardson Hikmicro HW Technologies Industry Update Invertec Performance Chemicals* Interflux* Inertec* Japan Unix* JBC* JS Electronic Keysight Technologies Kolb Cleaning Technology* KOH Young* Komax Kabatec* Leach (SZ) Co Ltd Lintek LPKF Laser & Electronics* Lumiloop* Machinery Forum Marque Magnetics Ltd Mastercut Technologies Mean Well* Mecal* Microchip Technology Australia Micron* Midori* Nano Components *Denotes - Co-Exhibitor Company/Brand Represented by Exhibitor electronex.com.au 48 B11 D14 A29 A29 D35 C5 B24 B24 B24 A16 A29 D10 A14 B7 B11 C5 C5 D12 C5 A19 D2 A1 C6 C18 B11 D37 B11 C2 C18 B3 A15 D14 A16 D14 C33 A6 D14 B32 C37 A27 A32 D33 D31 B15 A16 D37 B24 B24 D37 D8 A15 B24 B24 B24 D24 A9 D2 D14 C23 B6 A25 B11 B24 D11 C5 B11 B19 Electrone Melbourne Exhibition Centre – May 10-11 Electronex, the Electronics Design and Assembly Expo returns to the Melbourne Convention and Exhibition Centre on the 10-11th of May 2023. First held in 2010 and alternating between Melbourne and Sydney, Electronex is Australia’s major exhibition for companies using electronics in design, assembly, manufacture and service in Australia. T he SMCBA Electronics Design and Manufacture Conference will also be held, featuring technical workshops from international and local experts. In an exciting new development, Electronex will be co-located with Australian Manufacturing Week, with trade visitors now able to visit both events on the Wednesday & Thursday. Noel Gray, Managing Director of show organiser AEE said, “… there is significant overlap with Electronex focused on the high-tech end of manufacturing. Visitors from the manufacturing sector will now be able to see the entire spectrum of the latest products, technology and turnkey solutions for the electronics and manufacturing sectors at the one venue.” Visitors will need to register separately for each event, either online prior to the show or at the entrance to the Expos. Electronex stands are sold out and the show will feature a wide of range of electronic components, surface mount and inspection equipment, test and measurement and other ancillary products and services. Companies can also discuss their specific requirements with contract manufacturers that can design & produce turnkey solutions. Many companies will be launching and demonstrating new products and technology at the event; more than 100 local and international companies will be represented at this year’s Expo. The show attracts designers, engineers, managers, industry enthusiasts and other decision makers who Australia's electronics magazine Silicon Chip Electronex-SiliconChipAd 2023.indd 1 Thursday, 23 March 2023 8:20:31 PM are involved in designing or manufacturing products that utilise electronics. With many Australian manufacturers now focusing on niche products and high-tech applications, the event provides an important focal point for the industry in Australia. Free seminars A series of free seminars will also be held on the show floor, with no pre-booking required. These sessions will provide an overview of some of the hot topics and key issues for the industry. Topics include: • From Idea to Electronics Product, covering potential pitfalls and case studies • Innovations from Touch User Interface to Artificial Intelligence • Additively Manufactured Electronics for 3D Meta-Device Designs with Dynamic Beam-Shaping and mm-Wave On-Chip Radar Applications • Onshoring Manufacturing in Australia • The Importance of Customer Experience in Electronic Manufacturing and Port Protection • First Line Suppression Against Overvoltage Threat Visit the show website for times and session details. Trade and industry visitors to the Expo can register for free at www.electronex.com.au SMCBA Conference & Soldering Competition Since 1988, the Surface Mount & siliconchip.com.au neX 2023 Circuit Board Association (SMCBA) has conducted Australia’s only conference dedicated to electronics design and manufacture. The SMCBA will also be staging the inaugural Soldering Competition with support from members and suppliers. The competition will be held on the Expo floor next to the SMCBA and Oritech stands. 1st prize is a JBC Compact station! Keynote: Cheryl Tulkoff – Design for Excellence SME – Fleet Space Technologies Securing the Electronics Future: Technological Sovereignty Through Innovation & Collaboration explores the challenges and opportunities for the electronics industry to achieve technological sovereignty through innovation and collaboration. Cheryl will also present “The ABCs of DfX in Electronics Manufacturing”. Phil Zarrow – ITM Consulting In over 30 years of consulting, Phil Zarrow and Jim Hall have just about seen it all! Join the ‘Assembly Brothers’ for “SMT Assembly Troubleshooting and Process Optimization”, a journey through troubleshooting the most common defects in SMT with an emphasis on identifying the fundamental root causes, and an entertaining overview of SMT assembly process optimisation techniques. Jasbir Bath – Bath Consultancy Jasbir has over 25 years of experience in research, design, development and implementation in the soldering, siliconchip.com.au surface mount and packaging technologies. He will present “SMT Process Setup”. Jasbir will also speak on “SMT Process Development”, including optimising solder paste printing for different components on the board and development of the reflow profile to reduce soldering defects. Audra McCarthy – CEO, Defence Teaming Centre Inc The Defence Teaming Centre Inc is Australia’s peak defence industry body connecting, developing and advocating for Australia’s defence industry. Audra will present “The role of the Australian electronics sector in establishing a sovereign defence industry capability”. Matt Wild – Managing Director, Future Electronics Matt's presentation, “Supply Chain Strategies”, will cover the latest updates on the market for sourcing electronic components Chris Turner – Senior Test Engineer at ResMed Chris will share his key insights into Design for Test (DfT), gained from decades in the industry. Anthony Tremellen – SMCBA The “SMT Component Identification” presentation seeks to supply attendees with an extensive study of the surface mount components that are used in electronic assembly. For the full program, visit: www.smcba.asn.au/conference Nano Dimension Nordic Semiconductor* NPA Pty Ltd NZFH Ltd OceanVision Okay Electronics ONboard Solutions On-track Technology Oritech Oupiin* Permark Industries (Aust) Phoenix Contact Pillarhouse Soldering* Powertran* PPM Test* Precision Electronic Technologies Pros kit* QualiEco Circuits Quectel Wireless Solutions Radytronic* Rapid-Tech Raspberry Pi* Redback Test Services Rehm Thermal Systems* Reid Print Technologies Re-Surface Technologies Rigol Technologies* Ritec* Rohde & Schwarz (Australia) Rolec OKW - ANZ S C Manufacturing Solutions Salecom* Shenzhen FastPCB Tech Co Skyzer Smartronics Solar Electronics Company* Solar - EMC* Suba Engineering Successful Endeavours Sunon* Sun Industries Surface Mount & Circuit Board Association TDK Lambda* Tekt Industries Teledyne FLIR* Telit Centerion* Thermo Fisher* Topfast Technology UniMeasure* UNI-T Instruments* VGL - Allied Connectors Vicom Australia Viscom* Wago Whats New in Electronics Win-Source Electronics Wirepas* Wurth Electronics Yamaha* Yokogawa* YSX Tech Co Ltd A28 C33 A31 B25 D22 A29 B16 C26 D37 C5 D5 D26 A6 C5 C18 D25 C5 A7 C1 C5 A15 A19 D9 A16 D17 A32 A1 C5 C16 A22 A21 C5 D6 D16 A6 C18 C18 B24 A13 C5 D28 D30 C33 B19 A15 C33 B11 D27 B11 A15 B23 C20 A16 B10 A4 D18 A13 B20 A32 A15 C15 *Denotes - Co-Exhibitor Company/Brand Represented by Exhibitor electronex.com.au Australia's electronics magazine Electronex-SiliconChipAd 2023.indd 2 May 2023  49 Thursday, 23 March 2023 8:20:32 PM CNS Precision Assembly www.cns.org.au stand D10 Mycronic Pick-and-place production places components at up to 120,000/hour, from as small as 01005 size up to large BGA, including Micro-BGA and LGA devices. We can assemble a broad range of products into final manufactured goods, then package and ship them. We deliver precision assembly projects for a wide range of industries, including mining, rail, pools, security, sustainability, agriculture, LED lighting, IoT, smart cities, laboratory equipment, defence and aerospace. Our abilities extend to laser engraving and cutting. We can purchase all the parts, enclosures and mechanical elements as specified by the client or use customer-supplied components. We also offer rework servicing, including: • Disassembly • Part replacement/modification • Software loading/testing • Reassembly • Packaging Ethical, sustainable practices and policies are the core of our services. We strive for open and transparent relationships with customers, suppliers and the community. congatec Australia www.congatec.com stand A14 The COM-HPC Mini form factor suits ultra-compact high-­ performance designs such as DIN rail PCs or rugged handhelds and tablets. The COM-HPC Mini, with its 95×60mm footprint, is a real liberator, opening up entirely new high-performance perspectives – in particular for the many ultra-compact system designs. congatec introduces COM-HPC Size A (conga-HPC/cRLP) and COM Express (conga-TC675) computer-on-modules based on high-end 13th Gen Intel Core processors in BGA assembly. The new processors have long-life availability and offer vast improvements in many features, yet are fully hardware compatible with their predecessors, making implementation very fast and easy. With Thunderbolt and enhanced PCIe support up to Gen5, the modules based on the new COM-HPC standard open up new horizons in data throughput, I/O bandwidth and performance density. The COM Express 3.1 compliant modules help to secure investments in existing OEM designs, including upgrade options for more data throughput. New features provide significant improvements in a wide range of industrial, medical, artificial intelligence (AI) and machine learning (ML) applications, as well as all types of embedded and edge computing with workload consolidation. 50 Silicon Chip The added DDR5-5600 support and increased L2 & L3 cache on select variants provide outstanding multi-threaded performance. The computing core improvements of this performance hybrid architecture, which currently provides up to 8 performance-cores and 16 efficient-cores, are complemented by enhanced USB 3.2 Gen 2×2 bandwidth of up to 20 gigabits per second. Control Devices Australia Pty Ltd www.controldevices.com.au stand B7 Control Devices has added CPI waterproof switches to our diverse product line. CPI switches are designed to cater for demanding Industrial and Defence applications, where efficiency and reliability are critical under severe environmental conditions. Based on the users’ set parameters, the switches can meet the IP68 rating. They are protected with either a thermoplastic or neoprene rubber cover. The switches are fully submersible, splashproof, waterproof and wash-down resistant. They perform under exposure to water, salt water, oil, humidity, sand, dirt, vibration, shock and temperature. They come in various styles ranging from pendant, rocker, plunger, limit and ball switch styles. Momentary and maintained functions available. The switches can be mounted into a bracket to fit into confined spaces or a switch panel unit. Dyne Industries www.dyne.com.au stand D12 Dyne designs and manufactures custom-made transformers, power supplies & wound components, including: • Current transformers • Single and three-phase power transformers (0.1VA to 80kVA) • Airport lighting transformers – mains isolating & series isolating • Ferrite-cored transformers and chokes • Audio & high-frequency line isolation transformers for telecommunications, up to 25kV • Toroidal transformers • Inductors • Linear and switchmode DC power supplies • DC UPS backup systems Australian owned, Australian made to Australian & international standards. Emona Instruments https://emona.com.au stand A1 The best value in test gear just got better with the introduction of Rigol Technologies’ DHO Series of Digital High-­Resolution Oscilloscopes, featuring true 12-bit resolution, 70-800MHz bandwidths and two or four channels. The DHO Series is powered by the new UltraVision III platform featuring a custom ASIC chipset, giving dramatically lower front-end noise. The higher resolution and lower noise enable users to analyse much smaller signal artefacts faster and more accurately. DHO4000 oscilloscopes are available in 200-800MHz, four channels, 4GSa/sec sampling, 100μV/division range and 250MPts of memory standard (500MPts optional). DHO1000 Australia's electronics magazine siliconchip.com.au sales<at>controldevices.net www.controldevices.com.au LED INDICATORS LINEAR SENSORS ROTARY SENSORS TILT SENSORS INTERFACE MODULES HAND CONTROLS INDUSTRIAL JOYSTICKS FINGERTIP JOYSTICKS USB DESKTOP JOYSTICKS CONTROL LEVERS DIGITAL PANEL METERS FOOT PEDALS FOOT SWITCHES FLEXIBLE COUPLINGS ACCELEROMETERS INCLINOMETERS PCB SWITCHES PANEL SWITCHES TACTILE SWITCHES THERMAL SWITCHES VACUUM SWITCHES PRESSURE SWITCHES AIR SWITCHES GYROSCOPES ENCODERS PRODUCT SHOWCASE PUSH BUTTON SWITCHES ANTI-VANDAL SWITCHES LED INDICATORS FOOT & PALM SWITCHES WATERPROOF SWITCHES HAND CONTROLS MINIATURE JOYSTICKS TOGGLE SWITCHES PENDANT CONTROL STATIONS 10 - 11 MAY 2023 MELBOURNE (MCEC) Visit us at STAND B7 Brands WE REpresent www.controldevices.com.au Unit 13, 538 Gardeners Road Alexandria NSW 2015 siliconchip.com.au Australia's electronics magazine 02 9330 1700 May 2023  51 scopes offer 70-200MHz bandwidth, two or four channels, 1GSa/sec sampling, 500μV/division range and 50MPts of memory standard (100MPts optional). Both have 12-bit resolution and a 10.1-inch intuitive touchscreen display. They also incorporate Rigol’s new UltraAcquire Burst Capture mode, making it possible to visualise dynamic signals in multiple display modes while minimising downtime between trigger events. 12-bit resolution reduces the quantisation level between bits by a factor of 16 compared to 8-bit resolution for far superior precision. The new chipset also delivers a significantly lower noise floor than traditional oscilloscopes. Epson Singapore www.epson.com.sg stand C6 Epson Micro Devices is a major supplier of quartz timing devices. Epson’s core technologies in crystal photolithography and timing IC IP enable a wide range of product offerings, from crystals to RTCs, SPXOs, VCXOs and TCXOs. Epson’s semiconductor focus is on low-power design and efficient graphical display technology. Epson's product categories include display controllers, microcontrollers and ASICs. These enable interactive and user-friendly products such as smart watches, smart meters and automotive display solutions. Combining timing devices and semiconductors gives two small form factor products: inertial measurement units (IMUs) and accelerometers. These ultra-high-precision sensors are used in inertial navigation systems (INS), stabilisation and structural health monitoring (SHM). Led by the Japan-based Seiko Epson Corporation, the Epson Group comprises more than 73,000 employees in 91 companies worldwide. It is proud of its contributions to the communities in which it operates and its ongoing efforts to reduce environmental impacts. Glyn High-Tech Distribution www.glyn.com.au stand C33 The nRF7002 is a companion IC, providing seamless WiFi connectivity and WiFi-based location determination by SSID sniffing of local WiFi hubs. It is designed to be used alongside Nordic’s existing nRF52 and nRF53 Series Bluetooth Systems-onChip (S0Cs) and nRF91 Series cellular IoT systems-in-­package (SiPs). The nRF7002 can also be used in conjunction with non-Nordics host devices. Nordic brings decades of ultra-low-power wireless IoT and silicon design expertise to WiFi. With WiFi 6, we bring benefits to IoT applications like efficiency gains that support long-life, battery-powered WiFi operation. The chip supports all wireless protocols used in Matter, Bluetooth LE for commission, Thread for low-power mesh, and WiFi for high-throughput. Matter is a protocol championed by Apple, Amazon, Google, Nordic Semiconductor, Samsung, and hundreds of other companies in consumer IoT. 52 Silicon Chip The MPS EVMPC1100A-54-00A evaluation board demonstrates the capabilities of the MPC1100A-54-0000, a high-­ efficiency, monolithic, non-isolated LLC/DCX power card module with a fixed 10:1 transformer turn ratio. The evaluation board can deliver up to 60A continuously across a wide operating input voltage (VIN) range. High efficiency can be achieved across a broad output current (IOUT) load range. The MPC1100A-54-0000 employs MPS’s MP2981 digital LLC controller and the MP8500 smart synchronous rectifier. The MPC1100A-54-0000 is available in a surface-mount package measuring 27mm x 18mm x 6mm. It is PMBus/I2C Compatible, with built-in MTP to store custom configurations and monitors the input voltage, output voltage, output current, output power and temperature. TDK Rack DC Power Systems deliver 30kW, 45kW or 60kW in a portable 20U-high 19-inch rack cabinet. Part of the GENESYS+ programmable DC power supply series, these power systems are certified for safety under IEC/EN 61010-1 and carry both CE and UKCA marks following the Low Voltage, EMC (IEC/EN612043; industrial environment), and RoHS Directives. Uses include test and measurement, semiconductor processing and burn-in, automotive component and HIL testing, aerospace and satellite testing, high-power magnets, medical imaging, industrial automation, and process control. The FN980/FN980m LTE/5G data card supports 5G sub-6 and mm-Wave, SA and NSA operations plus 5G CAT 20, up to 7xCA, 256-QAM DL/UL, 2xCA UL with 4×4 MIMO for 4G and 5G (sub-6 bands) and 3G HSPA+. The LN920 High-Speed LTE / M.2 is a compact data card available in Category (Cat) 12 and 6 worldwide. They are pre-certified by Tier 1 operators and ideal for mobile computing, IIoT gateways and routers. They are powered by the Qualcomm Snapdragon X12+ LTE modem and support LTE bands between 600MHz and 3.7GHz, including CBRS (Band 48) and FirstNet (Band 14) plus LTE Cat 12 (3xCA and 600Mbps DL/150Mbps UL) and Cat 6 (2xCA and 300Mbps DL/50Mbps UL) with WCDMA fallback technology and embedded GNSS position and navigation. GPC Electronics www.gpcelectronics.com stand B32 GPC Electronics is Australia’s largest contract electronics manufacturer based in Sydney, with factories in Sydney (Australia), Christchurch (New Zealand) and Shenzhen (China). The company was founded in 1985 and now employs more than 400 professionals. Our experience and capacity, together with robust SAP MIIbased processes, continuous real-time quality monitoring, and highly trained professionals make GPC Electronics your ideal manufacturing partner. In today’s competitive market, customers expect fast turnaround, high yields and attractive pricing. GPC Electronics provides scalable solutions for high-value niche products through to high-volume products. Our services include NPI, Box Build, DfX, System Integration, printed circuit board assembly, cable harness assembly and testing. Australia's electronics magazine siliconchip.com.au Our customers are in fields as diverse as aerospace, defence, automotive, renewables, agriculture, space, consumer goods and unmanned systems. GPC Electronics is accredited with ISO 9001, ISO 14001, ISO 13485, IATF 16949, and AS 9100D. The company also holds a DISP accreditation. Hammond Electronics www.hammfg.com stand C37 Product designers have quickly adopted the new 1557 product family from Hammond. With a modern smooth style with rounded corners and top face, IP68 environmental sealing enables the unit to be installed in any environment. The 1557 can be used as a free-standing enclosure when fitted with the supplied feet, or it can be wall-mounted with either four visible fixings or two hidden ones. Four plan sizes, each in two heights in black and RAL 7035 grey, are available in UL Listed IP68 polycarbonate: 80 × 80 × 45/60mm and 120 × 120mm, 160 × 160mm and 200 × 200mm in heights of 45/70mm. PCB standoffs are provided in both the lid and base. For mounting heavier components, 2mm aluminium internal panels are available. The enclosure is assembled with corrosion-resistant M4 stainless-steel screws threaded into integral bushes for repetitive assembly and disassembly. The IP68 polycarbonate versions are UV stabilised for outdoor use with a UL94-5VA rating, while the IP66 ABS general-purpose versions have a flammability rating of UL94-HB for indoor use. Hawker Richardson https://hawkerrichardson.com.au/ stand A32 Hawker Richardson will be demonstrating the IMS-100 receiving station at Electronex. The IMS-100 reads up to four component reels at a time via bar codes and QR codes linking with MRP/ERP software in seconds. The high-resolution two-camera-based system scans and receives data from multiple suppliers once the templates have been set up. The image-based algorithm reads any bar code, even with defects. Processing a reel manually takes about ten minutes and is not 100% accurate. IMS-100 provides a rapid and accurate inventory count and integrates with any software system, which helps to identify stock shortages and inform and monitor SMT manufacturing processes. Full traceability is achieved with automatic unique identification number (UID) labelling as the operator removes each reel. Time and date stamp ID labelling enable production managers to keep track of sensitive components that expire, avoiding expensive waste. The IMS-100 can be integrated with the Scienscope Smart Storage Rack, the easiest way to store electronic components. Sensors detect when reels are pulled or placed, and UID labelling enables quick retrieval for production. Unlike most other systems sold with towers, the IMS-100 is flexible and can be purchased independently. siliconchip.com.au HIKMICRO stand D33 www.hikmicrotech.com/en/ The HIKMICRO AI56 acoustic imaging camera is a professional product for sound source localisation. With 64 low-noise MEMS microphones and an adjustable bandwidth from 2kHz to 65kHz, AI56 effectively locates pressurised air leaks or partial discharge in high-voltage systems. The results are presented on top of a digital picture on a large 4.3-inch LCD touchscreen. The maximum operating distance can reach 100 meters, providing a safe distance for inspecting high-voltage equipment. With this lightweight and easyto-use tool, you can discover potential safety risks, minimise troubleshooting and save on the cost of equipment failures and downtime. JS Electronic stand D8 Products on display include Rigid-Flex circuits that combine FR-4 area for dense components population interconnected with flexible polyimide that can be bent to accommodate packaging needs and Shield-Flex circuits that reduce interference and control impedance of signal lines. Machinery Forum www.machineryforum.com.au stand C23 The Mighty Vue Inspector is a magnifying lamp and camera inspection system in one self-contained unit, allowing you to view the image directly on an HDMI monitor, capture and store images on the included microSD Card, and even connect to your PC for viewing or relocating saved images, and additional software features. It is a three-diopter magnifying lamp with a built-in camera and has a frosted diffuser with colour temperature controls. Tilt the camera to adjust the on-screen image to your desired angle. Aven’s Wide View UV Magnifier is a handheld magnifier with ultraviolet and 18 white LEDs (4W total) with two intensity levels. It features a rectangular high-quality magnifying glass. It is ideal for dermatology, trauma treatment, schools, ophthalmology, forensic science, the hospitality/food industry, agriculture and industrial defect inspection. Microchip Technology www.microchip.com stand D11 Microchip’s new 1GHz SAMA7G54 is the first single-core MPU (mobile processing unit) with a MIPI CSI-2 camera interface and advanced audio features. Microchip is committed to maintaining the lowest power MPU portfolio in the market. The SAMA7G54 extends this trend into the 1GHz performance class of Linux-capable MPUs by providing flexible low-power modes plus voltage and frequency May 2023  53 scaling. It can be coupled with Microchip’s new MCP16502 Power Management IC (PMIC), supported by Microchip’s mainline Linux distribution for the SAMA7G54, allowing for easy entry and exit from low-power modes, plus dynamic voltage and frequency scaling. Microchip provides hardware and software development support for the SAMA7G54 via the SAMA7G54-EK Evaluation Kit (CPN: EV21H18A) and the bare-metal framework and RTOS support within MPLAB Harmony v3. For more details, see siliconchip.au/link/abki PolarFire SoC FPGAs unlock new configurable processing opportunities with their hardened real-time, Linux-capable RISC-V-based microprocessor subsystem on a fast FPGA fabric, backed by Microchip’s commitment to a product roadmap and long-term availability. The deterministic Asymmetric Multiprocessing (AMP) mode allows users to run a Linux OS while running a maximum-performance, real-time application. The Mi-V ecosystem removes barriers to entry, enabling embedded engineers, software designers and hardware developers to leverage the advantages of the RISC-V ISA and the PolarFire SoC FPGA’s combination of small form factors, thermal efficiency and low power consumption. For more details, see siliconchip.au/link/abkj The SAM9X60D1G-SOM is a 28×28mm hand-solderable module that includes an MPU and DDR in a single package, along with power supplies, clocks and memory storage. It is Microchip’s first SOM equipped with 4Gb of SLC NAND Flash to maximise memory storage of data in application devices, while the onboard DDR reduces the supply and price risks associated with memory chips. The small-form-factor SOM also includes an MCP16501 Power Management IC (PMIC), simplifying the power design effort to a single 5V voltage rail to enable lower-power systems. The SAM9X60D1G-SOM contains a 10/100 KSZ8081 Ethernet PHY and a 1Kb Serial EEPROM with pre-programmed MAC address (EUI-48). Customers can customise with security features like secure boot with on-chip secure key storage (OTP), hardware encryption engine (TDES, AES and SHA) and True Random Number Generator (TRNG). For more details, see siliconchip.au/link/abkk » RISC-V-based FPGA and space-compute solutions The PolarFire FPGA and SoC families already deliver the industry’s best thermal and power efficiency in the mid-range segment. Optimised for a high compute performance in small form factors, the families have reduced the size and weight of power-constrained systems in applications including industrial imaging, robotics, AI-enabled medical systems, smart defence and aerospace. For more details, see siliconchip.au/link/abkm » Industrial Gigabit Ethernet Transceivers with Precision Timing Protocol The LAN8840 and LAN8841 Gigabit Ethernet transceiver 54 Silicon Chip devices meet IEEE 1588v2 standards for Precision Timing Protocol. They deliver flexible Ethernet speed options, including 10BASE-T, 10BASE-Te, 100BASE-TX and 1000BASE-T. These devices facilitate critical packet prioritisation by providing high-speed timestamping that is relayed between the various components to determine network latencies, accommodate for those latencies, and synchronise time amongst all connected devices. This is key for process automation applications that require precise control production systems such as robotics, distributed sensors and cooling/mixing systems. The LAN8840/41 devices can withstand extended industrial temperatures ranging from -40°C to +105°C. The LAN8841 Ethernet Development System (EDS) Daughter Card is a modular addition to compatible Microchip host boards. When paired with the PCIe Networking Adapter, the LAN8841 can be evaluated through any host with a PCIe interface. For more details, see siliconchip.au/link/abkn » Radiation-tolerant PolarFire FPGA achieves MIL-STD-883 Class B Qualification The RT PolarFire FPGA family brings Microchip’s 60 years of spaceflight heritage to a product line that delivers the necessary computing and connectivity throughput for modern space missions. These FPGAs consume up to 50% less power than SRAM-based alternatives while enabling on-orbit data processing systems to meet demanding performance requirements with reliable operation and without excessive heat generation. Their unique combination of Logic Elements (LEs), embedded SRAM, DSP blocks and 12.7Gbps transceiver lanes enables higher resolution for passive and active imaging, more channels and finer channel resolution for multi-spectral and hyper-spectral imaging and more precise scientific measurements using noisy data from remote sources. For more details, see siliconchip.au/link/abko » Smart metering platform on 32-bit MCUs with MPL460 PLC modem The PIC32CXMT family comes in three variants based on a single Arm Cortex-M4F core, a dual Arm Cortex-M4 core and a system-on-chip (SoC) device. The MPL460 PLC modem integrates the line driver for signal amplification, which reduces the bill of materials and maintains a top-performing signal injection efficiency above 40% due to its Class-D topology. The PLC modem increases efficiency and reliability based on power delivered to the load and power taken from the supply, resulting in an overall reduction in consumption from the source during transmission. The platform supports several transceiver options, including a radio/PHY, a PLC/PHY or the option to select a PLC+RF hybrid solution. There is also an option for a metrology and communications software suite compliant with ANSI and IEC metering standards, up to class 0.2% accuracy. It also supports wired and wireless communications, such as G3-PLC and PRIME. For more details, see siliconchip.au/link/abkq Nano Dimension www.nano-di.com stand A28 The DragonFly IV is a multi-material 3D printer that generates circuits in one step, including connections and components! By simultaneously 3D printing dielectrics, metals and using 3D space, the DragonFly IV is a new way to design and prototype electronics. Features and benefits include FLIGHT software for freeform electromechanical design and miniaturisation; the elimination of wastewater, toxic chemical waste and reduced energy Australia's electronics magazine siliconchip.com.au siliconchip.com.au Australia's electronics magazine May 2023  55 requirements; in-house design and production; preventing IP theft by retaining your designs within your organisation; and a reduction of manual labour and assembly times. Essemtec provides an outstanding competitive advantage by combining high-speed placement and jet dispensing in a single pass on one machine. Our machines incorporate the latest intelligent feeder concept with 200 feeder lanes on 1m2 for nonstop production and traceability. It is currently the highest number of feeders per m2. This enables the placement of a large variety of components, from the smallest parts (01005 imperial) up to 80×80mm, with a precision of ±45μm (3σ). FOX and PUMA are unique platforms, combining three processes: solder paste jetting, adhesive dispensing and pick & place in one machine. Depending on the application, five valves are available. The machine can be equipped with single, double or quadruple placement axis modules. Benefits include a small footprint with no vibration, an expandable modular system customised to customers’ applications and high flexibility for prototype development. SPIDER and TARANTULA are versatile high-speed dispensing machines equipped with state-of-the-art technology. These are guided by smart software features enabling a wide range of applications. Benefits include combined dispense processes with up to three dispense valves per process, automatic process control for dot-size detection and adjustment and support for structural and electric conductive glues, solder paste, underfill, glob top, dam and fill and gasketing. NPA www.npa.com.au stand A31 Bushings, grommets and plugs are essential in the manufacturing and cable management industries; they help to improve the performance, safety, and efficiency of products and systems. These components protect and manage cables, hoses, and other types of conductors and are found in various applications, from automobiles and machinery to consumer electronics and computers. From vibration-resistant grommets to explosion-proof plugs to right-angled strain relief bushings, NPA stocks an impressive range of cabling components that can be shipped to you by the next business day in most cases. Spacers and standoffs provide crucial support and physical separation for components on a PCB. They help to prevent short circuits and can also help reduce vibration damage and shock. This makes them ideal in demanding applications where the circuit boards are subjected to extreme conditions. By providing physical separation, these components can reduce the amount of electrical interference between components, improving signal quality and reliability. They also help with head dissipation, improving longevity and performance over time. Spacers and standoffs are available in various materials, including Nylon, metal, and ceramic to meet application requirements. 56 Silicon Chip NPA supports local manufacturing by stocking hundreds of different types of spacers to suit almost any requirement. They can be delivered to you the next business day in most circumstances. Bootlace ferrules (also known as crimp ferrules or wire ferrules) are metal connectors that secure the end of a wire in electrical applications. They come in various sizes to accommodate different wire gauges. Bootlace ferrules provide a secure, low-resistance connection between a wire and another component, such as a terminal block, terminal strip, or connector. They provide a connection that is resistant to vibration and mechanical stress, making them ideal where the wire and connector may be subjected to rough handling, such as in industrial or automotive environments. Ocean Vision https://i-submerge.com stand D22 Ocean Vision Environmental Research, based in Perth, is a specialised developer and manufacturer of high-quality marinegrade sensors and electronics. We provide high-quality products and services for marine & estuarine environmental monitoring, solutions for live fish transport & monitoring, and control equipment for research and commercial aquaculture. Ocean Vision undertakes bespoke development and applied scientific research and development, delivering marine-grade sensors and associated devices, electronics and computing equipment, tools and software, remote data collection systems, habitat mapping and biostatistics and spatial analysis under the i-Submerge Scientific and i-Submerge Aquaculture brands. Designed for up to IP67, the G-series enclosures blend form and function, with a high-quality physical design that is modular, functional and rugged. Conceived for marine electronics – for fish transport modules and deck interface units for underwater camera systems – the series has been expanded to deliver a flexible multi-purpose range of rugged enclosures. Key features include an extruded anodised aluminium body available in full-body, single-opening or dual-opening configurations with various sizes and opening configurations; integrated external heatsinks and mounting slots on all exterior surfaces; end panels are available in aluminium, stainless steel, carbon fibre and Nylon with a range of watertight and dustproof sealing options. The i-Submerge G-series will be available with a range of accessories to support your intended application, including integrated battery power, intelligent battery management, permanent and removable mounting options, integrated LCD screen options, rugged waterproof connectors and innovative cable glands. The i-Submerge i-Gland range provides improved sealing and cable retention compared to standard glands using specialised O-ring carriers. Australia's electronics magazine The carriers utilise bevelled edges to convert axial force from the compression nut into strong compression of the primary cable seal O-ring against the cable sheath. This ensures an effective seal across a wide range of cable tolerances. The O-ring carriers have a set of bore O-rings that seal between the carriers and the gland body. This sealing action is independent of the primary cable seal and provides a standard bore (piston) O-ring seal between the outside diameter of the carriers and the gland body. This design provides high cable retention and is watertight and dustproof. These glands will be available in various sizes and body styles, including models with three or more O-ring carriers for increased sealing, cable retention and durability. Okay Technologies https://okay.com.au stand A29 Co-exhibitors: AIM Solder Australia, AIM training – IPC training centre, Chemtools, Thermaltronics Soldering and Robots & Nihon Superior SN100C lead-free solders. AIM Training (a division of Chemtools) is a licensed IPC training centre that has led the way with IPC training in Australia since 2007. AIM Training delivers comprehensive and certifiable courses covering all areas of electronics. Along with a range of IPC training courses, their offerings include customised training courses for through-hole and SMT production, master micro rework, repair and diagnostics for mobile devices and ESD awareness. Courses can be conducted on customer premises or in Chemtool’s fully equipped IPC training centre. Chemtools employs three full-time trainers, all certified in electronics, and provides IPC training to many defence organisations in Australia, including Raytheon, Boeing, BAE Systems, Rheinmetall, SAAB, CEA Technologies, Thales, Lockheed Martin and Northrop Grumman. We conduct IPC training in all states of Australia and New Zealand. Unlike typical Cartesian robots, the Thermaltronics TMTR8000S Soldering Robot is equipped with full vision to verify the procedure being undertaken and does not simply follow a pre-determined program. It has an observation mode, a verification mode and decision-­making capabilities. This capability of collecting and utilising data for production processing is one of the most critical factors in meeting the requirements of Industry 4.0 standards. The Thermaltronics Robot system can accurately provide high-speed operation, repeatability and durability. Application programming is made simple by using full image-merging and mapping techniques. Dynamic laser height measurement/ adaptive control ensures precision soldering repeatability. A full vision mapping and matching system provides intelligent decision-­ making during procedural operations. ONBoard Solutions www.onboardsolutions.com stand B16 ONBoard Solutions is an ISO 9001 credited supplier of manufacturing equipment, cleanroom products and advanced materials to the Australian and New Zealand market. siliconchip.com.au We are committed to offering the best quality products at the right price, delivered on time, every time. We provide ongoing support in the selection and use of our products. This way, we ensure the products are used correctly and compliant with your applications. HumiSeal UV92 UV Curable Masking Gel is a soft, one-part UV curable masking material. It is a thixotropic paste that applies easily because of its shearing thinning viscosity profile and is 100% cured by exposure to UV, providing a temporary barrier to prevent the ingress of coatings to keep-out areas. HumiSeal UV92 has excellent solvent resistance that provides selective release from conformal coating. The gel can also survive intermittent exposure to temperatures up to 150°C and is REACH and RoHS compliant. It applies easily by syringes and dispensing machines, keeps contact points and connections free of coating, will not tarnish gold, tin, copper, phosphor bronze or Sn/Pb solder and is easily removed by peeling. It leaves no residue to interfere with subsequent operations. Special offer: receive a free sample of HumiSeal UV92 UV Curable Masking Gel, 55cc. Valid during Electronex Exhibition 2023 while stocks last. ONBoard Solutions reserves the right to change or rescind this offer at any time. Promosolv 70ES Cleaning & Flux Removal Solvent is a specialty solvent to clean the residues from solder pastes and solder fluxes. It is clear, colourless and has only a slight odour. It can be used with ultrasonic cleaning. Its medium-range boiling point and very low surface tension provide outstanding flux removal and drying characteristics when used in the vapour phase with azeotropic mixtures. The formulation provides an increased solvency power over the Promosolv 70. Rehm Thermal Systems ProtectoXC & ProtectoXP Conformal Coatings provide the highest quality, stability and productivity in automatic inline coating services. With up to four coating applicators, you can synchronise several modules simultaneously in master-slave mode to apply the coating or directly apply with up to four different materials without set-up time. The same nozzle can switch between dispensing, spraying and jetting procedures ‘on the fly’. Parts that are high up or close together are easy to reach thanks to the slim nozzle design that is only 2.4mm in diameter and up to 100mm long. If necessary, parts can be flushed from below due to the patented Vario Coat nozzle. Rehm Thermal Systems has designed and created ViCON software that meets all the requirements of modern, networked electronics manufacturing. Smart mechanical engineering and best-in-class software mean the Protecto machine is the first digitally-driven conformal coating machine. The Series 86 Battery Bonding System from F&S Bondtec is a heavy-wire version of the automatic wire bonders in our Series 86 featuring exchangeable bond heads. A fully automatic mode makes it ideally suited for medium-scale production. Parts to be bonded are fed manually by the operator, but the bonds are produced without operator influence. The F&S Bondtec Series 86 Battery Bonding System offers maximum flexibility through a working area of up to 512 × 720mm for applications such as battery bonding. Australia's electronics magazine May 2023  57 QualiEco www.qualiecocircuits.com.au stand A7 QualiEco Circuits is celebrating its 20th Anniversary in 2023! We have been offering standard and fast turnaround PCB manufacturing and assembly services in Australia and New Zealand since 2003. We hold ISO9001:2015 certification in Australia and New Zealand and are pursuing an ISO13485:2016 certificate, to be received by April 2023. The Team at QualiEco Circuits is known for providing excellent quality electronic manufacturing services and solutions. Customers can choose from the fastest to semi-fast and standard delivery options based on their budget and urgency. This dynamic, growing company offers outstanding technical support and attention to detail. QualiEco Circuits is currently a market leader in New Zealand. The company is now enjoying a successful 11th year of operation in Australia. The technical team at QualiEco Circuits has regularly prepared a guide on various technical aspects of PCB manufacturing and assembly, available at www.qualiecocircuits.co.nz/ publications.htm We offer complete solutions in specialised PCBs – give wings to your imagination! We can produce rigid PCBs (up to 32 layers), flexible PCBs (single & multi-layer), rigid-flexible PCBs (single & multi-layer) and metal core PCBs (single & multi-layer). Quectel Wireless Solutions www.quectel.com stand C1 Quectel’s 5G modules connect IoT devices with cutting-edge cellular networks, enabling applications as diverse as remote surgery, autonomous driving, virtual reality, gaming, AI-driven smart manufacturing and robotics. Our LTE and LPWA modules have exceptionally small footprints, can be equipped with multi-receiver GNSS capability for satellite positioning and come standard with multiple-­input multiple-output (MIMO) technology that greatly reduces errors, reduces power consumption and ensures reliable data speeds. See www.quectel.com/shop/?wpf_filter_cat_1=287 Quectel’s Smart IoT modules combine previously separate functionalities like computing, graphics processing, data storage and connectivity into highly compact pieces of hardware. Smart modules support a rich set of peripheral components such as cameras, LCMs, WiFi, Bluetooth, GNSS, memory and SD cards, eSIM and embedded universal integrated circuit cards (eUICC). Smart modules also have integrated operating systems – often Linux for industrial IoT or Android for commercial solutions – plus device drivers and associated SDKs. See www.quectel.com/smart-iot-modules Quectel is a leading supplier to the automotive industry, providing durable, compliant and reliable hardware to enable the new generation of smart vehicles. See www.quectel.com/ automotive-iot-modules Quectel’s WiFi module range offers high data rates, low latency and high network density features. See www.quectel. com/wifi-iot-modules Quectel’s wide range of ultra-compact, low-power GNSS modules cover the full range of requirements in standard precision, high precision, dead reckoning and timing, for application scenarios as diverse as ADAS and self-driving, unmanned flight, and smart agriculture. See www.quectel.com/gnss-iotmodules 58 Silicon Chip Quectel’s high-quality off-the-shelf and customised high-performance antenna portfolio boosts wireless connectivity significantly. Our new Combo antennas combine high-­ performance cellular, WiFi, Bluetooth and GNSS antennas and are ideal for use with Quectel’s 5G, 4G, WiFi and GNSS modules. See www.quectel.com/services/antenna Quectel Connectivity Solutions consolidate IoT modules, antennas and connectivity into a single point of provision, greatly simplifying product rollout and helping solution providers of any size to undertake mass deployments more efficiently across multiple regions. See www.quectel.com/iot-­ connectivity-services Quectel Certification Services offer a comprehensive certification and testing portfolio, including professional services and management tools. Our pre-scan service can assess certification compliance before applying to certification authorities, and we offer technical support and debugging solutions. We can guarantee a six-to-eight-week certification process for Quectel module customers’ devices. See www.quectel.com/ testing-certification Rapid Tech www.rapid-tech.com.au stand A15 The new Pendulum Model CNT-104S multi-channel frequency analyser measures frequency, time, phase, and time interval error simultaneously and is gap-free on four parallel inputs. It can make parallel frequency measurements of four test objects, phase comparisons of four stable reference clocks or multistop time interval measurements (one start and three stop). The 7ps resolution and 20MSa/s enable you to follow smaller and faster transient timing events than ever before. These measurements were never before possible in a compact benchtop unit without a lot of extra instrumentation. The standard frequency range is up to 400MHz and an optional RF input extends bandwidth to 24GHz. Applications include: oscillator and other test systems (replacing four traditional UFCs, a huge space and cost saving); time metrology labs; physics research, wireless communications, aerospace and defence. The new UNI-T range of digital oscilloscopes – UPO1000CS, MSO2000 and MSO3000E – are built on proven UNI-T technology. The MSO3000E family offers an 8-inch touchscreen design handling gestures such as click, slide, zoom, edit, drag etc. The portfolio offers rich measurement functions, ultra-high Australia's electronics magazine siliconchip.com.au capture rate, 70Mpts per channel memory, a wealth of advanced trigger and bus trigger functions, built-in dual-channel function arbitrary waveform generator, two or four analogue channels and optional 16-digital channels at a budget price with fast delivery. Bandwidths are from 100MHz to 500MHz, with higher bandwidths to be released. The area trigger can be combined with basic, advanced, or protocol triggers to capture occasional and complex signals. Bode plot capability can be used for loop analysis, while web control allows easy access from PC or mobile devices if required. The new UNI-T UTG9000T series integrated AWG offers four independent channels generating accurate and stable pulse/ function/arbitrary waveforms with direct digital synthesiser (DDS) technology up to 600MHz with 1μHz resolution. Features include accurate, stable and low-distortion signal generation; simple operation with a 10.1-inch capacitive touchscreen; high-frequency pulse signals up to 200MHz with rapid rising and falling edges can be generated. The UTG9000T allows coupling and merging between channels for added flexibility. The digital protocol output function supports SPI, IIC and UART, while PRBS can be added to any basic waveform. The UTG9000T features include a frequency meter that covers 100mHz to 800MHz providing high-precision frequency measurements without additional instruments. There is also a noise generator that can produce random or repeatable noise with very long repetition rates for simple problem identification. Multiple modulation modes include 3FSK and 4FSK, while sweep types include linear, logarithmic, stepping and frequency list sweep. Pseudo-random binary sequence (PRBS) allows ideal and distorted patterns up to 120Mbit/s. The new UNI-T UTS3000B range of RF spectrum analysers can measure up to 3.6GHz with superior performance at an affordable price. The series adopts mature all-digital IF technology with up to 40,001 points and provides multiple analysis functions with a 10.1 -inch touchscreen. Advanced features include support for analog and digital demodulation analysis, tracking generator, waterfall mode for spectrum measurement over time for interference and source stability testing, adjacent channel power analysis, EMI pre-compliance analysis function, plus a peak table function that directly displays all signal peaks. The UTS3000B provides USB, LAN and HDMI interfaces standard and optional GPIB with support for SCPI protocol for easy programming and remote control. Redback Test Services www.redbacktest.com.au stand D9 μISP In-System Programmers are based on WriteNow! technology. They are professional universal programming instruments dedicated to the programming and testing of devices. μISP can either work connected to a host PC (RS-232, USB, and LAN connections are built-in) or in standalone mode. The programming cycle can be started by simply pressing the START button in standalone mode or using software/TTL control lines for process automation. Their compact size and versatility allow simple integration into production environments such as test fixturing or service applications like field repair and firmware upgrades. Need a gang programmer? Ask about our range of WriteNow! ISP programmers. siliconchip.com.au Reid Print Technologies https://reidprinttechnologies.com.au stand D17 Reid Print Technologies is Australia’s leading manufacturer of printed electronics, specialising in wearables and smart garments. The Reid Sense Smart Insole integrates several smart data-collecting variables, including friction and pressure monitoring. The insole has been carefully engineered to collect important data for human health. It then uses Bluetooth to send information to an electronic device for tracking, analysis and reporting. Rohde & Schwarz www.rohde-schwarz.com stand C16 The new Rohde & Schwarz (R&S) MXO 4 Series oscilloscope provides the world’s fastest real-time update rate of more than 4.5 million acquisitions per second. This enables engineers to see more signal detail and infrequent events than any other oscilloscope, providing an unparalleled understanding of physical layer signals and faster testing. The integrated, industry-leading 12-bit ADC has 16 times the resolution of traditional 8-bit oscilloscopes at all sample rates without any trade-offs, providing the most precise measurements. A standard acquisition memory of 400Mpts on all four channels gives the instrument up to 100 times the standard memory of comparable instruments. The MXO 4 Series also features a unique 200Gbps processing ASIC. The R&S MXO 4 Series features a 13.3-inch full-HD capacitive touchscreen and an intuitive user interface. The instrument’s small footprint, very low audible noise, VESA mounting and rackmount kit for installation makes it an ideal oscilloscope for any engineering workspace. Other market-leading features include: • industry-leading 18-bit architecture • fastest and most accurate spectrum analysis in its class • industry’s deepest standard memory of 400Mpoints per channel • industry’s fastest trigger rearm time of 21ns • first-in-class to incorporate newer digital triggering technology • industry’s most sensitive trigger of 1/10,000div • best-in-class trigger jitter of <1ps • first oscilloscope with dual-path protocol analysis Rolec OKW ANZ www.rolec-okw.com.au stand A22 Rolec OKW Australia New Zealand Pty Ltd is the Australasian subsidiary of OKW Gehausesysteme GmbH and Rolec Gehause-Systeme of Germany. We supply high-quality plastic, aluminium and stainless steel enclosures for the OEM electronics manufacturing industry. Our program includes three market-­leading enclosure brands, OKW, Rolec and Metcase; all comply with the requirements of ISO 9001:2015 for the design, manufacture and distribution of plastic and metal enclosures. Australia's electronics magazine May 2023  59 Suba Engineering Pty Ltd www.suba.com.au Rolec OKW supplies fully finished enclosures with all machining and modifications completed at the factory. Our extensive range includes handheld, wearable, desktop, wall-mount and flush-mount enclosures, portable instrument cases, DIN rail enclosures, potting boxes and accessories. Potentiometer and tuning knobs include the latest models for menu-driven electronics. Enclosures and tuning knobs provide solutions for a wide variety of different applications, including medical, laboratory and wellness equipment, test and measurement, control, automation, mechanical engineering, plant building, automotive engineering, climate control, construction equipment, security and building management systems, military/aerospace, communications and network technology. Enclosures include solutions for power supply and installing standardised displays; high protection classes; high-­quality and easy-to-clean materials; recessed tops for membrane keypads and displays; recesses for interfaces and connectors. Accessories include docking stations, battery compartments and contacts, belt clips, wrist straps, lanyards, bedrail clamps, wall-mounting kits, tilt and anti-slide feet, cable glands, grommets and strain relief kits, IP sealing kits and Torx screws to help prevent tampering. Customising options include CNC machining, lacquering, printing or laser marking of legends and logos, decor foils, special materials, EMC shielding, installation and assembly. Shenzhen FastPCB Tech Co Ltd www.szfastpcb.com stand D6 Our 5000m2 facility, built in August 2000, has 300 staff members – including 50 QA (quality assurance) and QE (quality engineering) engineers. We produce 20,000m2 of PCBs each month. With advanced equipment, we produce 2-16 layer PCBs and provide one-stop service from PCB to PCBA, including BOM sourcing. Customers include computer OEMs and aviation and industrial manufacturers. From the beginning, we have complied with the ISO9001:2000 quality management system and strictly operate according to 5S SOP. We are experienced and aimed at constantly improving our service. PCB assembly specifications include a component height of 0.2-25mm, minimum component size of 0201, lead pitch of 0.2-2.54mm, BGA pitch of 0.25-2.0mm, BGA ball diameter:0.1-0.63mm and board sizes from 50×30mm up to 510×460mm. We make PCBs with 2-16 layers on FR-4, High Tg Fr4 or Halogen-­free high-frequency board (Teflon, Rogers). Board thicknesses range from 0.2-6.0mm with 4/4 mil minimum track width/clearance, 0.2mm minimum hole size, surface finishes of HASL, Immersion Ni/Au, ENIG, OSP, gold finger etc and special processes including buried/blind holes, impedance control and flex-rigid board. 60 Silicon Chip stand B24 The SubaScope 28 4K is a digital auto-focusing microscope that delivers incredible 4K resolution at any focusing height, with HDMI and LAN connectivity. It is designed and assembled in Australia. Its features include: • Amazing Auto-focus 4K (3840×2160) • 3A image processing technology, providing clear photos and crisp colours • 60fps over HDMI connection or 20fps to a PC over a LAN • HDMI & RJ45 LAN multiple video output options (monitor & PC) • Auto-focus works at nearly any height (starting from 10cm) • Up to 28x zoom level standard • Standalone microscope software with features to aid and improve the analysis (image and video capturing, measurement software, digital comparison, browsing and playback etc) • Included software license for computer operation The adjustable counterbalanced arm provides incredible versatility and mobility, translation and rotation in all six axes, making it an extremely powerful tool. Successful Endeavours www.successful.com.au stand A13 Successful Endeavours solves complex problems through electronics design and embedded software. It is Australian-owned and operated with a focus on making products in Australia. Manufacturing is the best way to generate local jobs because many other jobs are created around each direct manufacturing job. It also creates fundamental value and lots of product and process challenges to keep the research community fully engaged. Successful Endeavours has tackled more than 2000 projects over the past 25 years and has extensive experience across a broad range of product and industry categories, including winning Industrial Product of the Year in 2022 at the Manufacturer’s Monthly Endeavour Awards. Successful Endeavours has in-house prototyping capability. When you are ready to manufacture, we can introduce you to some excellent local contract electronics manufacturers. We want to see your product “Made in Australia” and a commercial success. Vicom Australia/Tektronix www.vicom.com.au stand C20 The 2 Series MSO is the first portable oscilloscope to offer benchtop performance with the award-winning Tektronix user interface. Weighing less than 2kg and just 40mm thin, it can fit into a small backpack, delivering unmatched performance and portability. The easy-to-use 10.1-inch touchscreen display makes working on the go easier and faster. The optional built-in arbitrary function generator (AFG), pattern generator, digital channels, voltmeter, and frequency counter provide extra versatility, Australia's electronics magazine siliconchip.com.au additional T-bar optimally positions inline connectors in the box. There is a labelling surface on the back of the box. The new WAGO Gelboxes offer unbeatable protection anywhere inline electrical connections are exposed to moisture and humidity, such as outdoor environments. WIN SOURCE Electronics www.win-source.net reducing the number of instruments to carry or purchase. With up to eight hours of battery power, engineers will also discover a new level of freedom on the job. WAGO Pty Ltd www.wago.com.au stand B10 The WAGO Group is an international, standard-setting supplier of electrical interconnection products, automation products and interface electronics. The family-run company is the world market leader and inventor of spring pressure connection technology. WAGO products are used globally in power and process technology, building automation, machinery and equipment, plus industrial and transportation applications. The WAGO Group comprises nine international production and main sales locations, 20 additional sales offices and the M&M Software specialist. Representatives in over 80 countries give the company a strong global presence. Boasting a nominal cross-section of 2.5mm2 (maximum 4mm2 without a ferrule), WAGO’s TOPJOB S Mini Terminal Blocks support more machines in more places. As more powerful miniature terminal blocks, the 2250 and 2252 Series supplement the currently available 1mm2 variant. Despite a compact design, the new variants can be used in applications up to 24A (maximum 32A without a ferrule) and 800V(IEC)/600V(UL). Both versions of the WAGO Mini Terminal Block (1mm2 and 2.5mm2) offer tremendous flexibility: they can be mounted on a 15×5mm DIN-rail or a mounting plate with snap-in feet or mounting flanges. They are available with either an operating slot or push-button actuation. Both types also offer direct push-in termination. WAGO’s Inline Splicing Connector condenses the industry-­ leading 221 Series splicing connectors’ advantages into a slim design. With unsurpassed simplicity, speed and reliability, the 221 Series levers provide a tool-free universal conductor connection and a transparent housing that allows users to confirm conductor contact at a glance. Where multiple poles are required, optional adaptors provide completely modular mounting. Users get the flexibility of having five fixed-position poles in one adaptor – with or without strain relief, on DIN rails with a snap-in mounting foot, for screw mounting, adhesive mounting, tie-on mounting or suspended mounting. WAGO now also offers three new Gelbox models for easy, quick and reliable IPX8 moisture protection of inline electrical connections – for two, three and five lever-actuated 221 Series Inline Splicing Connectors. An siliconchip.com.au stand D18 WIN SOURCE Electronics is Asia’s largest online store for electronic components. The independent parts distributor has been doing business for more than 24 years and has a wealth of distribution knowledge and experience. A big differentiator for WIN SOURCE is that it stocks more than one million electronic component products that can each be purchased directly through the company’s online store with 24-hour shipping. That includes hard-to-find, outdated electronic components, which can all be purchased directly from the online store without the need for repeated confirmation. WIN SOURCE has developed an extensive supply chain, which lets developers, design engineers and purchasing managers acquire products at very advantageous pricing, reducing production costs for OEMs and EMS vendors. At the same time, it improves the overall efficiency of the electronics supply chain and allows OEMs to focus on manufacturing R&D. WIN SOURCE consultants have expertise in the latest technologies and applications, including artificial intelligence (AI), automation and the Internet of Things (IoT). WIN SOURCE Electronics affirms that it will always adhere to the highest and most comprehensive quality systems and standards, including AS9120, ISO 13485, ISO 9001, and ESD S20.20, in its processes. Post-pandemic, WIN SOURCE understands the importance of long-term business relationships and pledges to further improve the stability of its supply chain according to ISO 22301 and ISO 28000 standards. Distributors play the pivotal role of connecting upstream and downstream of the supply chain. So, finding a reliable supplier is a must. Current counterfeiting technology is so advanced that even with the latest testing equipment and a professional thirdparty testing agency, it is difficult to completely distinguish is genuine or new parts from fake, brand new or refurbished. Würth Electronics Australia www.we-online.com stand B20 www.wurth.com.au WürthElektronik eiSos Group manufactures electronic and electromechanical components and is a technology company that spearheads pioneering electronic solutions. WürthElektronik eiSos is one of the largest European manufacturers of passive components and is active in 50 countries. Production sites in Europe, Asia and North America supply a growing number of customers worldwide. Their product range includes EMC components, inductors, transformers, RF components, varistors, capacitors, resistors, quartz crystals, oscillators, power modules, wireless power transfer, LEDs, sensors, connectors, power supply elements, switches, push-buttons, connection technology, fuse holders and solutions for wireless data transmission. The unrivalled service orientation of the company is characterised by the availability of all catalog components from stock without minimum order quantity, free samples and extensive support through technical sales staff and selection tools. Würth Elektronik is part of the Würth Group, the global market leader in developing, producing, and selling fastening and assembly materials. SC Australia's electronics magazine May 2023  61 By Alan Cashin GPS-Disciplined Oscillator The GPS-Disciplined Oscillator (GPSDO) is built almost entirely in software, so it only requires a PIC, an oven-conditioned crystal oscillator and a few other supporting parts. It provides an extremely accurate 10MHz signal with an error in the parts per billion range. T here are a few situations where having a very accurate frequency is essential. Many pieces of test equipment, such as oscilloscopes and spectrum analysers, have an internal 10MHz reference that’s accurate to within a few Hz (around one part per million). They usually have an input socket for a more precise external signal source for operating with much higher precision. As people explore high and higher operating frequencies, reference accuracy becomes more critical. An error of 1 part per million (ppm) at 7MHz is only 7Hz, hardly noticeable in a single-­sided band (SSB) signal). But at 5GHz, the same error is 5kHz, enough for the signal to not be received at the expected frequency. Global Navigation Satellite System (GNSS) satellites have accurate atomic clocks onboard that are adjusted by signals from ground-based master clocks. The satellites broadcast signals with precise timing that allow a GPS receiver to determine the receiver’s location and the time. Many GPS receiver modules generate an accurately timed one pulse per second (1PPS). This project describes a GPSDO that uses the 1PPS signal to adjust (discipline) the frequency of a 10MHz oven-conditioned crystal oscillator (OCXO). The output is accurate to a few parts per billion (ppb) at worst and normally 1ppb or better. GNSS and GPS GPS refers to the constellation of navigation satellites launched by the US government but is sometimes used to describe any positioning system that uses satellite data for navigation. Last century, the only useful constellation was the GPS constellation. More recently, many nations have launched their own satellite constellations, such as GLONASS (Russia), BeiDou (China) and Galileo (Europe). We published a detailed article on this subject in the November 2019 issue (siliconchip.au/Article/12083). The term ‘global navigation satellite systems’ (GNSS) refers to all the available constellations. Many “GPS” receivers are actually GNSS receivers and can use data from several constellations. This means the receiver is more likely to pick up usable signals since many more satellites are available to it. However, there are differences between constellations, and the receiver may be less accurate if it switches between constellations. Designing a GPSDO You will need a GPS module with an SMA socket and 5-pin header, such as the Neo-7M shown above. Make sure the header is wired as per Fig.2. 62 Silicon Chip I first became interested in GPSDOs after reading the GPS-Based Frequency Reference by Jim Rowe (March & April 2007; siliconchip.au/Series/57). In theory, a microcontroller could replace most of the discrete Australia's electronics magazine components. To test this, I designed a GPSDO that used a PIC16F628A. It worked, but was too elaborate. I decided to improve my old design after seeing Tim Blythman’s Programmable GPS-synched Frequency Reference (October & November 2018 issue; siliconchip.au/Series/326), which has an accuracy of ±100ppb. The aim of this was to create a useful and inexpensive GPSDO that could deliver 10MHz into 50W with a maximum error of 0.01Hz. It is based on a cheap CTI OSC5A2B02 oscillator, a PIC16F1455 microcontroller and a 74HC04 hex CMOS inverter running from a 5V supply. The GPS module I used was the cheapest available, the u-blox NEO-6 (possibly a clone), using an active antenna with a 3m lead. There was no need for any display; anyone with a smartphone can see their position and get accurate time, so such a display is redundant. The operational status is indicated with a single LED. This prototype system performed well enough to justify creating a PCB, and several were built. However, it was overly sensitive when connected to other equipment. Another problem was that I had not designed the PCB with any enclosure in mind, so it needed a larger enclosure than necessary. And people may prefer a 12V supply rather than a 5V supply. Consequently, I designed the revised PCB that is presented in this article. The oscillator is substantially independent of the rest of the circuitry. The PCB fits a UB3 Jiffy box and runs from 12V DC. How it works The GPSDO is designed to use a 1PPS signal and NMEA (National siliconchip.com.au Marine Electronics Association) serial messages delivered at 9600 baud. Many GPS receivers have these capabilities in a wide range of prices and feature sets. The GPSDO counts the cycles of the local oscillator between successive 1PPS signals. Any deviation from ten million causes a change in the control voltage to ensure there are ten million cycles per 1PPS. The oscillator is locked to the 1PPS signal, and so it can be used to accurately time long periods, as well as provide an accurate frequency. In the long term (days or weeks), a GPS receiver provides a very accurate time signal. But in the short term (second to second), there can be variations due to receiver design, signal reception and other factors. Many GPSDO implementations use specialised GPS receivers designed to minimise these variations and allow for relatively straightforward control strategies. This GPSDO was designed to use low-cost GPS modules that deliver a time signal with significant shortterm variations. To overcome this, the processor uses the average of many 1PPS signals to produce a more accurate result. The oscillator control is then varied at intervals of many minutes rather than continuously. The default is 512 seconds, but this can be changed through the user interface (UI). This approach has benefits and shortcomings. One benefit is that the GPSDO can evaluate its own performance. Because the control is varied by a known amount after a known interval, a maximum error can be attributed to the oscillator output before the correction is applied. The drawback is that the local oscillator’s phase (the amount of lag or lead) can be greater than it would be with a PLL (phase-locked loop) design. But like a PLL design, the local oscillator is locked to the 1PPS signal in the long term. clock; in this case, they are the 16-bit timer Timer1 and the 10-bit PWM (Pulse Width Modulator) generator. Timer1 is used to measure the arrival time of the 1PPS signal. The 1PPS signal is one input to a comparator, with the other set to 1.9V from an internal voltage reference. The 1PPS signal swings from 0V to 3.3V, so the comparator can easily detect it. The comparator is set up to gate (pause) Timer1 when the signal arrives. Another timer (Timer2) is used to count 10 million cycles, then start Timer1 at a known point. Since Timer1 is clocked at 40MHz, the interval until it is stopped is known to within 25ns. This is compared to a target arrival time, so it can determine if the pulse arrived early or late compared to the local oscillator. From this, we can deduce whether the oscillator is running slow or fast. 25ns is a sufficiently short interval for timing when using a low-cost GPS module. The 1PPS is generated from the GPS module’s internal clock, which is not necessarily a multiple of 10MHz. Consequently, the pulse will not arrive precisely on time, but will appear to jitter around the correct value. This randomises the arrival time so that accumulating the arrival times over a period gives a statistically more accurate average arrival time. Also, the 1PPS pulse timing is affected by atmospheric conditions, the transition between GNSS constellations and other effects, so measuring to better than 25ns yields little improvement. The oscillator frequency can be varied by a few hertz on either side of 10MHz, based on a control voltage applied to the oscillator. The OSC5A2B02 has a nominal control voltage of 2V±2V and a sensitivity of around 0.1V/Hz. The PWM peripheral generates the required voltage, with its output going through a filter More capabilities All a GPSDO has to do is time the arrival of the 1Hz pulses and adjust the control voltage to correct any deviation of the oscillator from 10MHz, as described above. However, it is desirable to be able to determine if the GPS unit is generating valid pulses, measure the GPSDO’s performance, and indicate to users that it is functioning correctly (or not). The GPS module generates NMEA messages as 9600 baud serial data (the micro can be programmed to handle Photo 1: the preferred position for mounting the PCB on a UB3 enclosure. In more detail I chose a PIC16F1455 for the microcontroller as it has several useful peripherals. Its clock signal is the 10MHz output of the reference oscillator, which allows the micro to count the 1PPS pulses directly. The processor has a PLL to multiply this by 4, giving an internal 40MHz clock. Some of the inbuilt peripherals can use this siliconchip.com.au with a time constant of over a second to eliminate all traces of the pulses. The output pulses of the PWM unit are at 40kHz, with the pulse width variable from 0 to 25µs in 25ns increments. If the pulse width is only changed when a change of control voltage is required, there would be 1000 voltage steps between 0V and 5V, which would change the frequency in increments of 5ppb. This is too coarse to be helpful. The traditional way to tackle the problem is to add more hardware. Typical solutions are to use PWM over a smaller range and have a potentiometer to make a coarse adjustment; combine the output of two PWMs, one for coarse control and one for fine control; or use an external DAC (digitalto-­analog converter) with 16 bits (or more) of resolution. This GPSDO solves the problem in software by dithering the pulse width on every pulse. Selected pulses are made 25ns longer. The base number for this is a 24-bit number, allowing the control voltage to be varied in increments of less than 1µV. This is far finer than required, but as it is generated in software, it is effectively free. The unique pulse stream repeats more than twice a second, so the heavy filtering is adequate to remove any artefacts created by the dithering. Australia's electronics magazine May 2023  63 Fig.1: the GPSDO is built around oven-controlled crystal oscillator OCXO, GPS module MOD1 and microcontroller IC4. IC4’s clock is derived from the oscillator’s 10MHz output, and it analyses the 1Hz pulses from the GPS module to determine if the control voltage needs to change. That voltage is produced by error-diffused PWM buffered by Mosfets Q1/Q2 and filtered by a three-stage LPF. the less common 4800 baud). The GPSDO decodes the messages, looking specifically for $xxRMC messages (xx because some modules output $GPRMC [GPS], some use $GNRMC [multi-constellation] etc). RMC is the recommended minimum message, so almost all GPS modules will deliver it. One field in the message indicates if the GPS has a valid location fix. The GPSDO ignores the 1PPS pulses if the fix is not valid. Although not necessary for GPSDO operation, other messages are decoded to obtain data useful for logging such as the date and time. The GPSDO uses a single LED to indicate its status. The LED has patterns for error conditions, startup stages and operational status. When the OCXO is locked to the GPS 1PPS signal, the LED repeats a pattern once 64 Silicon Chip per second. A single 50ms flash indicates the OCXO should be within 1ppb of 10MHz. Otherwise, there are two closely-spaced 50ms flashes indicating the accuracy is uncertain. A UI is provided to obtain more status information, and some limited control over the GPSDO, via the microcontroller UART. By default, the NMEA data stream from the GPS module is passed through to the UART. Programs are available to decode the information and display items such as the number of satellites in view, their signal strength, position in the sky and the location data’s reliability. This can be useful to diagnose performance issues. The UI can also be accessed by a terminal program such as TeraTerm. The user can change the output from the NMEA stream to a log of what the GPSDO is doing. There are some Australia's electronics magazine control functions to change some defaults, reboot or update the software without removing power. Circuit details The entire circuit is shown in Fig.1. The controlling PWM signal produced by IC4 emanates from pin 7 and is fed to the gates of P-channel & N-channel Mosfets Q1 and Q2, which operate as an inverter. When the PWM signal is low, Q1 switches on, pulling the output up via a 10kW resistor, whereas when the PWM signal is high, Q2 switches on, pulling the output low via another 10kW resistor. The resulting signal is fed through three RC low-pass filters connected in series to the control terminal (pin 1) of the 10MHz crystal oscillator (OCXO). The time constant of this filter is around one second. siliconchip.com.au The main reason for inverting the PWM signal with two Mosfets was so the input to the PWM filter can have its amplitude determined by a very precise reference voltage for stability in the resulting control signal, generated by a MAX6350 voltage reference IC. However, testing showed that it was sufficient to isolate the PWM supply from the general 5V supply. The 5V rail from the standard linear regulator that powers the OCXO is stable enough that the MAX6350 IC is not required. Therefore, constructors should omit REF5 and instead solder a wire from the output of REG6 to REF5’s pad 6 (the dashed line in Fig.1). Regardless of the source of the reference voltage, it is fed through an LC low-pass filter (1mH/47μF) before being applied to the source of Mosfet Q1 to remove any digital noise. siliconchip.com.au The output signal from the OCXO at pin 3 is fed through an inverter (IC7a) and 22pF AC-coupling capacitor to the clock input pin (pin 2) of microcontroller IC4, which has an internal DC bias. It’s also fed to the remaining five inverters in IC7 connected in parallel, with series resistors on the outputs to prevent them from ‘fighting’ each other if they don’t switch simultaneously. The output of this set of inverters is AC-coupled to output connectors CON7 & CON9 with a 1kW resistor to provide 0V DC bias. An opto-isolated serial interface is provided at CON5, which can be plugged straight into a USB/serial converter module. By isolating it, we prevent electrical noise from being fed back from a connected computer. Isolation is via two opto-couplers, one Australia's electronics magazine for each direction (in/out) – OPTO1 & OPTO2. As for the power supply, the incoming 12V is filtered by a 100μF capacitor and then fed into a buck converter module (REG1) that efficiently drops it to 6.5-7.5V. Its output is filtered by a 220μF capacitor, then an LC low-pass filter to remove most of the switching noise (100μH/470μF) before being applied to two 5V low-dropout linear regulators, REG3 & REG6. REG3 powers microcontroller IC4, hex inverter IC7, the GPS module and some other bits and pieces, while REG6 powers the crystal oscillator and PWM control signal inverter, as mentioned earlier. Both regulators will remove any remaining switching noise from the buck regulator that passes through the LC filter. The GPS module is wired to CON6. May 2023  65 We recommend you use this type of USB/serial module, as it makes the overall wiring much easier. Note the non-standard orientation of Q1; see the panel on p68. The 1PPS signal is fed to pin 8 of IC4 while the serial stream goes to pin 12. The PCB has provision for data to be fed in from a GPS receiver via dual-differential receiver IC3. This is an experimental interface to allow remote location of the GPS receiver for situations where a local GPS antenna cannot pick up adequate GPS signals. The connection to the remote receiver utilises a standard Ethernet UTP cable, with two pairs for the two signals and the remaining pairs for 12V power. The remote end requires a buck converter, a line driver and the GPS receiver. This setup has been tested over a 12m cable, and worked over 20m. However, I did not design a PCB for this. If you wish to implement this, fit the line receiver IC using a socket. For remote use, install the line receiver. For local use, remove the line receiver and plug the GPS receiver into CON6. Otherwise, IC3, CON8 and the two associated 100W resistors can be left off. Preparing the enclosure Before mounting any parts on the PCB, use it as a drilling template for the mounting holes on the Jiffy box lid, which will become the base. Refer to Photo 1, which shows the preferred position for a UB3 enclosure, with the power connector close to the back and plenty of space for mounting the buck converter module. efficiency), although with the small flag heatsinks specified, that should not bother the regulators. The prototype used an LM2596based buck converter module with an adjustable output, set to 7.0V (6.5-7.0V is the ideal range). As it has suitable onboard capacitors, the 100μF and 220μF supply capacitors on the main PCB can be omitted. It was attached edge-on using a few pieces of solid copper wire scavenged from an Earth conductor; no additional support was necessary (see the photo below). With a UB3 Jiffy box, this converter just fits between the posts in the lid. You can do something similar, but using the specified regulator is neater and easier, and you don’t have to be so concerned with the exact mounting position of the PCB on the lid. If you want to use an adjustable buck regulator module, consider the MINI360 (SC4399; siliconchip.com.au/ Shop/7/4399), which is small, inexpensive and can deliver up to 1.8A. Construction The control PCB is coded 04103231 and measures 100 × 55mm. Refer to the overlay diagram, Fig.2, during construction. Begin the PCB assembly by fitting the only SMD component, inductor L1. It’s reasonably large and easy to handle but requires quite a bit of heat to flow the joints. Turning the iron up will help. First, spread a thin layer of flux paste on the pads and add some solder to one. Place L1 over its pads and use something to clamp it in place while adding solder to the sides of the two pads, one at a time. Once the solder contacts the inductor, it will solidify, and you will have to hold the iron there, continuing to apply heat until it melts again and flows to form a proper joint. When it remelts, feed in some extra solder until you have nice shiny fillets. With that in place, move on to the through-hole parts, starting with the resistors. All but one are mounted vertically to save space. While doing that, use one of the lead off-cuts to fit the wire link shown in red in Fig.2, bypassing the unused REF5. Follow with the two TO-92 Mosfets, being careful not to get the different types mixed up, then the ceramic capacitors, which are not polarised. Next, install the electrolytic capacitors, which need to have the longer positive leads inserted into the pads marked with a + symbol. The striped side of the can indicates the opposite (negative) lead. Then solder the opto-couplers (OPTO1 & OPTO2) plus hex inverter IC7. These can all be soldered to the board without a socket, but make sure pin 1 is in the right location in each case before soldering. Now fit microcontroller IC4, you can solder it to the board as there is The LM2596 module is inexpensive and adjustable, but mounting it can be messy. Buck converter We have specified a low-cost 7.5V 1A buck converter that should be a direct fit on the PCB, similar to a standard linear regulator. The 7.5V option provides plenty of headroom but will increase dissipation in the case (ie, reducing 66 Silicon Chip Australia's electronics magazine siliconchip.com.au provision for in-circuit programming/ reprogramming (ICSP) via CON3, but you might prefer to use a socket to make it easier to replace. If IC4 is programmed before installation, CON3 is not needed as updates can be made via the UI on the serial port. Next, install the linear regulators (REG3 & REG6) plus the buck regulator module (REG1), making sure they are orientated as shown in Fig.2. For REG1, various types can be used, and it isn’t always obvious which way around they should go. Check the module and verify that the input and output pins match the “IN” and “OUT” labels shown in Fig.2. After that, fit the OCXO, which can only be inserted into its pads in the correct orientation. We don’t recommend you fit IC3, CON8 or the two resistors next to IC3. Similarly, REF5 should be missing, although you will have already soldered a wire link to its pad 6. You can now fit the DC socket to complete the board. LED1 can be mounted on the PCB, but it is more convenient to fit a twopin polarised in its place and wire up the LED to a matching plug using a length of light-duty figure-8 cable (eg, two wires stripped from ribbon cable). That will let you mount it in a hole in the case later, so it’s externally visible. Similarly, the 10MHz output socket is chassis-mounted and connected via a two-pin header, CON7. It isn’t critical that this is a polarised/locking type header; you could use a standard header and DuPont plugs or just solder the wires to the output socket to the pads, although that does make disassembly/testing a bit more difficult. Fit a standard six-pin header for the isolated USB/serial interface at CON5. The specified USB/serial module has a socket that will plug into this header later. The direct serial interface header, CON4, should not be needed. Once the PCB has been assembled, it needs to be wired to the output socket, GPS module, USB socket and LED1. Note the omitted optional parts. Programming the micro If you purchased your microcontroller from Silicon Chip, it will come programmed. Otherwise, if you have a blank micro, you can fit CON3 and program it using an in-circuit serial programmer like a PICkit 3/4 or a Snap. The PICkit 3 or 4 can supply power to the board during programming. For the Snap, arrange for your own 5V supply or temporarily connect a 12V supply to the board to program the chip. siliconchip.com.au Fig.2: fit the components as shown here, taking care with the orientation of the electrolytic capacitors, ICs, opto-couplers, regulators and LED1. Several parts are not needed and are shown left off, while CON8 and the two 100W resistors below it are depicted but not required. Don’t forget the short wire link near the middle of the board, shown in red, which bypasses REF5. Australia's electronics magazine May 2023  67 Once the chip has been programmed, you don’t need to open the box to access CON3 to reprogram it. This can be done over the serial port using the XMODEM protocol. Testing Before applying power, check your soldering for unwanted shorts, especially around the Mosfets. Also check to ensure the fillets are all shiny and well-formed, all components are in the correct locations and have the right orientations. If using an adjustable buck converter, verify that you’ve set it for approximately 7V output before connecting it to the main PCB. This is not critical as it can be adjusted later, during testing. The converters used on the prototypes are adjusted by rotating the onboard potentiometer screw anti-clockwise. Nothing happens for much of the rotation, then the voltage reduces over very little travel. Connect the LED to its header, apply power and check that it lights up or flashes. Check the output voltage from the buck module at either end of inductor L1 relative to 0V (eg, one of the two larger plated holes on either side of unused socket CON8). Verify it’s close to the expected voltage (6.57.5V). Also measure the outputs of the two 5V regulators at their tabs and verify they are both close to 5V. If the LED is not flashing, probe pin 3 of the PIC. It should be switching between 5V and 0V. If it is, you might have the LED connected the wrong way around. If the LED flashes at 2Hz, the 10MHz signal is not reaching the PIC at its pin 2. Check for a 10MHz signal between the two pins of CON7. It should also be present at pin 1 of IC7 (directly connected to the output of the oscillator). If all is well, the LED should flash at 1Hz with about 800ms on and 200ms off. This indicates that the PIC is working and using the 10MHz from the oscillator as its clock. You can check the control voltage at the control pin of the OCXO, which is connected to the right-hand end of the resistor immediately between it and REF5. It should be in the range of 2-3V, most likely close to 2.5V. If that’s wrong, it could be due to a problem BS250 Pinout Be aware that there are versions of the BS250 Mosfets with non-standard pinouts (the standard pinout is DGS left-to-right looking at the flat ‘label’ side; see Fig.1). If you end up with those, you might need to rotate it or bend the pins. Usually the non-standard versions have their pinout printed on the face. Fig.3: this shows where to drill holes in the lid/base, for mounting the PCB, and in the sides of the case, for the various chassis-mounting connectors. As noted in the text, you should ideally use the PCB as a template to mark the four holes in the lid/base, although you can use this diagram if you’ve already populated it. Note: the DC socket and GPS antenna socket locations are only guides, and the actual size and location can vary when it is mounted. So it’s best to check them before drilling. 68 Silicon Chip Australia's electronics magazine siliconchip.com.au with Mosfets Q1 and/or Q2 or a faulty oscillator module. GPS module wiring You can now solder the wires from your GPS module to the pads for CON6. Fig.2 shows the wire colours for the suggested Neo-7M module. However, you might decide to use a module with an onboard antenna if you have good signal strength in your lab. It is best to use an active antenna on a lead as the signal quality indoors is usually too marginal. The antenna is ideally placed outdoors with a good view of the sky. Adequate signal may be obtained indoors near openings such as a window. If using a different module, consult its data sheet to determine the connections. Most TTL modules should be suitable. The specified module has a standard 5-pin header, so a short 5-way ribbon cable with DuPont connectors at either end will suffice to connect it to the CON6. In contrast, the VK2828U7G5LF module has an onboard miniature connector and comes with a matching cable with bare ends, so you could solder its wires directly to the board. It also has an enable (EN) wire that needs to connect to the 5V pad. The system can now be powered up with the GPS module attached. There’s a power light on most GPS units; if present, it should light up. If the system LED is now making a double flash at three-second intervals, all is well. That indicates that data is received from the module but isn’t seeing any satellites yet. Next, plug the USB/serial module into CON5; make sure it’s the right way around, with its DTR pin to pin 1 on the left and its GND pin on the right. Connect it to your computer, open a serial terminal on the COM port that appears, power up the board, and you should see one line of text when it detects that it is running with the 10MHz clock. With the GPS module attached, it should pass through the NMEA data to the serial output (this is the default when first powered up, but you can change it later). Place the GPS antenna where it will receive a good signal from the satellites. Turn the system on, and the double flash at three-second intervals should resume. It could take up siliconchip.com.au The finished PCB; note the wire soldered to pin 6 of REF5 to bypass it (on the underside). to 30 minutes or possibly a little longer for the GPS module to pick up all the satellites after a ‘cold start’. When that happens, the LED flash pattern should change. The LED reports the number of satellites seen (in binary) until a fix is obtained. This may take some time, sometimes as long as 15 minutes. If the system stays in the double-flash state, the antenna may not be in a good position, or it isn’t working. Final testing If the GPS module is locating satellites, the system should transition after some time to a flash pattern every four seconds. It starts as five flashes, a single followed by four doubles, and counts down. If there is no flashing, it is most likely that the GPS module has reported a good fix, but the 1PPS signal is not getting to the PIC processor. Do not allow the system to run for more than an hour after this transition. Turn it off, detach the GPS module, and run the system without the GPS for a few hours or overnight. The reason is that most crystal oscillators need time to settle down after unknown handling before being installed. Calibration The GPSDO is self-calibrating. The purpose of the calibration is twofold; it determines the actual sensitivity of the crystal oscillator (the control voltage vs frequency relationship) and a reasonable control voltage to use when the system is started. After the oscillator has been running for a few hours, turn off the system Australia's electronics magazine and reattach the GPS module with its antenna. Let the system run until it delivers one flash every second. This will take more than an hour, and if the GPS signal is marginal, it may be longer (or not achieved – in which case the antenna needs relocating). A single flash per second indicates the GPSDO has completed calibration and has reached 10MHz within 1ppb. A double-flash suggests it may not be within specification. It is normal to see an occasional period of double flashing, for a few minutes every few hours. This is due to the GPS switching satellites and not having a good fix immediately. A well-positioned antenna will reduce or eliminate these deviations. After the GPSDO has been switched off, it will take some time to settle down the next time it is turned on. Usually, it is unusable for up to five minutes and reliable after 15 minutes. For best results, the system should be allowed to run continuously. It improves noticeably for the first week of running. If the antenna is well-­ positioned, the system should then single-flash (indicating a precision better than 1ppb) and rarely, if ever, double-flash. Completion Once you’ve verified that it’s working, all that’s left is to finish mounting it in the case. Mount it on the base by inserting 8-10mm long machine screws from the outside, into 5mm spacers. Drop the PCB on the screw shafts, then use a set of nuts to hold it in place. May 2023  69 Fig.4: we’re recommending a USB/serial module with a micro-USB socket that plugs directly into CON5 (it has an onboard header socket). However, you can use most USB/serial adaptor you want, including the very common type shown here, wired to a 6-way female header to match CON5. Check that the DC socket will line up with the location of the hole shown in Fig.3, then make it. If it’s too low or high, you can adjust either the hole’s location or the size of the spacer between the PCB and the lid. Make the other required holes, too; if your arrangements differ from what we’ve suggested, you might need to adjust some of the hole positions and sizes. If your GPS module has an onboard antenna, you can attach it to the inside of the case using double-sided tape. Otherwise, drill the hole for the antenna connector and mount the GPS module to that hole. You will probably need to use neutral-cure silicone sealant to glue it inside the case as the SMA socket does not have a retaining nut; the threads are only for the SMA plug. Various approaches can be used for the USB interface. On the prototypes, we wired up a low-cost USB/serial adaptor, as shown in Fig.4, then wired it up to a chassis-mounting ‘extension cable’ style USB socket. However, we think we’ve come up with an easier and neater solution for the final version. The USB/serial adaptor specified in the parts list plugs directly onto header CON5 (watch the orientation). You will then have a micro-USB socket facing up from the PCB (as shown in the photos). The parts list also specifies a chassis-mount micro-USB socket with a short cable that plugs right into that socket. That just leaves the output connector. If you haven’t crimped and soldered the output connector wire with the polarised plug at one end and BNC socket at the other, do that now, then mount it on the side of the case where it won’t interfere with the PCB. Plug it into CON7 and check that the connector shell has continuity to the PCB ground. Finally, check that everything is working before ‘buttoning up’ the GPSDO in its case – verify that the LED flashes when power is applied, a ~10MHz signal appears at CON9, and you can establish USB communications via the chassis socket. Make sure the GPS antenna is plugged in and it is ready to use. The HEX file, source code and documentation for the GPSDO can be downloaded from the S ilicon Chip website; or from the author’s GitHub: https://github.com/ajcashin/ budget-gpsdo SC Australia's electronics magazine siliconchip.com.au Parts List – GPS-Disciplined Oscillator 1 double-sided PCB coded 04103231, 100 × 55mm 1 12V DC 500mA+ supply with barrel plug 1 UB3 Jiffy box (optional) 1 PCB-mount DC socket (CON2; 2.1mm or 2.5mm ID, to suit plugpack) 1 5V GPS module with 1PPS output and SMA antenna socket [eg, NEO-6M, NEO-7M or NEO-8M; SC6737] (MOD1) 1 GPS antenna with wired SMA connector [SC6738] 1 CTI OSC5A2B02 oven-conditioned crystal oscillator module (X1) [eBay www.ebay.com.au/itm/332389156868] 1 12V input, 7.5V 1A output three-pin buck converter module (REG1) [SC6739] 1 WeMos style CH340G-based USB/serial module with header socket for serial and micro-USB socket (MOD3) [SC6736; AliExpress siliconchip.au/link/abjn] 1 10cm panel-mount micro-USB socket to micro-USB plug (for MOD3) [SC6736] 1 10×10mm 100μH 1A+ SMD inductor (L1) [ASPI-8040S-101M-T or NR10050T101M] 1 1mH axial RF inductor (L2) 1 5-pin header (CON3; optional, for programming IC4 in circuit) 1 4-pin header (CON4; optional, for non-isolated serial) 1 6-pin header (CON5; for isolated serial) 2 2-pin polarised headers and matching plugs (CON7, CON8) 1 panel-mount BNC socket (CON9) 1 100mm 5-way female-to-female DuPont cable (CON6; NEO GPS module) 2 flag heatsinks for TO-220 devices [eBay 182609295159] 6 M3 × 8-10mm panhead machine screws 4 M3 x 5mm tapped Nylon spacers 2 M3 shakeproof washers 6 M3 hex nuts 2 M2 × 10mm panhead machine screws and hex nuts (to mount USB socket) 1 200mm length of twin-core light-duty figure-8 cable (eg, stripped from ribbon cable) Semiconductors 2 4N25 or 4N35 opto-isolators (OPTO1, OPTO2) 1 UA9639CP dual differential receiver IC (IC3; optional) 1 PIC16F1455-I/P 8-bit microcontroller programmed with 0410323A.HEX, DIP-14 (IC4) 1 74HC04 hex inverter IC, DIP-14 (IC7) 2 LM1085-5.0 low-dropout 5V linear regulators (REG3, REG6) 1 BS250 P-channel Mosfet, TO-92 (Q1) 1 2N7000 N-channel Mosfet, TO-92 (Q2) 1 3mm LED (any colour) Capacitors 1 470μF 10V radial electrolytic 1 220μF 10V radial electrolytic 2 100μF 16V radial electrolytic 3 47μF 50V radial electrolytic 3 10μF 50V radial electrolytic 4 100nF 50V MKT or multi-layer ceramic 1 22pF 50V NP0/C0G ceramic Resistors (all ¼W 1% axial metal film) 3 10kW 2 5.6kW 5 1kW 5 270W 3 100W – two of the 100W resistors are optional (used only when IC3 is installed) 70 Silicon Chip Subscribe to APRIL 2023 ISSN 1030-2662 04 9 771030 266001 $1150* NZ $1290 INC GST INC GST WIDEBAND Fuel Mixture DISPLAY Silicon chirp Your own pet crick et Australia’s top electronics 500 cl as s d am pl ifier magazine use two inexpensive pre-b uilt modules to make the 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. W A T T Published in Silicon Chip If you have an active subscription you receive 10% OFF orders from our Online Shop (siliconchip.com.au/Shop/)* Rest of World New Zealand Australia * does not include the cost of postage Length Print Combined Online 6 months $65 $75 $50 1 year $120 $140 $95 2 years $230 $265 $185 6 months $80 $90 1 year $145 $165 2 years $275 $310 6 months $100 $110 1 year $195 $215 2 years $380 $415 All prices are in Australian dollars (AUD). Combined subscriptions include both the printed magazine and online access. Try our Online Subscription – now with PDF downloads! How We Communicate Underground; April 2023 500W Class-D Amplifier; April 2023 Silicon Chirp; April 2023 Advanced SMD Test Tweezers; February & March 2023 An online issue is perfect for those who don’t want too much clutter around the house and is the same price worldwide. Issues can be viewed online, or downloaded as a PDF. To start your subscription go to siliconchip.com.au/Shop/Subscribe ▶ Factory-calibrated oxygen sensor ▶ Compact size, fitting in a 120 x 70mm case ▶ Correct sensor heat-up procedure implemented ▶ Optional exhaust pressure correction for readings ▶ Several display options, including wireless via Bluetooth ▶ Wideband and narrowband O2 sensor compatible outputs ▶ Accurate air/fuel ratio and lambda measurement and display ▶ Switch between displaying air/fuel ratios for two different fuels Part 2 of John Clarke’s WIDEBAND Fuel Mixture Display Our new WFMD (for short) uses a Bosch LSU4.9 wideband sensor to show a running engine’s live air:fuel ratio and/or lambda. It displays both on an LED panel display or another device via Bluetooth, and it can be permanently installed in a vehicle or temporarily inserted into the exhaust pipe for tuning. This second article in the series mainly covers the circuit details. L ast month in the first article on the new WFMD, we went into quite a bit of detail on how a wideband oxygen sensor works and how this particular circuit functions. However, we ran out of space in that issue, so we still needed to show the complete circuit diagram and explain how it works in detail. Due to the size of the circuit and its description, we will have to end it there, so the third and final article next month will cover the construction, testing, calibration and operation of the WFMD. Circuit description Fig.12 shows the entire circuit. It’s based on a PIC16F18877-I/PT microcontroller (IC1) in a 44-pin TQFP SMD package, running with an internal 32MHz clock oscillator. siliconchip.com.au The remainder of the circuit includes a pressure sensor (connections at upper left), Mosfet Q1 (for the sensor heater), some op amps and a few other components. Each op amp is a rail-to-rail type, meaning that the input and output pins can swing to within a few millivolts of the supply rails. They run from different supplies, so some can swing over 0-5V, some -3V to +12V and some 0-33V. We use the input and output pins on microcontroller IC1 in a few different ways. Its digital outputs can produce either a low (0V) or a high (5V) voltage. That allows us to switch LEDs or transistors on or off, or control anything that requires a digital signal. With the digital inputs, for example, we can detect if a jumper is connected to ground or left open with an internal pullup current to 5V from the micro. Australia's electronics magazine We can also set a pin to monitor a voltage ranging from 0V to 5V, with IC1 converting the voltage to a 10-bit digital value ranging from 0 to 1023. This is called an analog (AN) input. For example, ANC4 is the analog input on portC, bit 4, located at pin 42. Some digital outputs can be used for pulse width modulation (PWM), producing a fixed-frequency rectangular wave with a varying duty cycle. The duty cycle is the proportion of time the output is high and can vary from 0% through to 100%. When zero, the output is always low. At 50%, the waveform is square with equal periods at 0V and 5V. At 100% duty, the output sits at 5V. The PWM signal can be used directly to drive a component such as a Mosfet, or the waveform can be lowpass filtered to produce a varying DC May 2023  73 Fig.12: the full circuit uses microcontroller IC1, several CMOS op amps (IC2-IC4) and a Mosfet (Q1) to control the heater in the oxygen sensor, plus a pressure sensor. The microcontroller and op amps monitor and control the wideband oxygen sensor and provide the narrowband output, air/fuel ratio voltage and lambda outputs for monitoring using a multimeter, V/A panel meter or via Bluetooth. 74 Silicon Chip Australia's electronics magazine siliconchip.com.au siliconchip.com.au Australia's electronics magazine May 2023  75 voltage. The filtering converts a digital value to an analog voltage, provided the filter rolls off the AC signal amplitude well below the PWM frequency. In our circuit, PWM outputs are labelled from PWM0 to PWM6. PWM0 to PWM5 produce 31.25kHz waveforms, while PWM6 runs at around 122Hz. Driving the oxygen sensor Trimpot VR2 across the 5V rail provides the 3.3V reference voltage, which is buffered by op amp IC4c. This op amp drives one side of the pump cell, at the Vs/Ip connection, via a 150W resistor which isolates the op amp output to ensure stability. The Vs/Ip voltage is measured at the ANA4 input of the microcontroller to ensure that the pump current can be set to zero by applying the same voltage (from the PWM5 output) to pump drive buffer stage IC3a. IC3a is driven from the PWM5 output of IC1 (pin 27) via a 10kW resistor and 100nF filter capacitor to produce a steady DC voltage. The duty cycle of the 31.25kHz PWM signal is varied from 0-100% to produce a DC voltage ranging over 0-5V. IC1’s PWM2 and PWM1 outputs (pins 35 & 36) provide the external wideband and narrowband voltage outputs, respectively, again using PWM control. The narrowband output from PWM1 is filtered with a 1MW resistor and 100nF capacitor before being buffered by op amp IC2b. The filter components give a relatively slow response to PWM duty cycle changes, like a narrowband sensor. The 100kW resistor in series with buffer IC2b gives a high output impedance to simulate a narrowband sensor. For the air/fuel ratio output, the PWM2 output is filtered via a 10kW resistor and 100nF capacitor and amplified by op amp IC2a. This provides a wideband output at MV+, suitable for monitoring with a multimeter or a voltage and current (V/A) panel meter. The MV+ output is usually set to show 14.7V for petrol and 15.5V for LPG at lambda 1.0. Trimpots VR5 and VR6 set the gain of IC2a for the required air/fuel ratios. For the AF1 selection, the AND1/ RD1 output (pin 39) is set low (0V), allowing the gain to be set by VR5. The VR6 trimpot is connected to an analog input (AND0) at pin 38, which is effectively open-circuit. If the AF2 output is selected, the AND0 output is changed from an analog input to a low-level digital output. VR6 then sets the gain, with VR5 now connected to a high-impedance analog input (AND1). Jumper JP3 at the RC3 digital input (pin 37) selects between AF1 and AF2. When no shorting jumper is present, AF2 is selected. AF1 is selected when the jumper is shorted. Pin 37 has an internal pullup current configured to hold the input high when no jumper is connected. The AF1 and AF2 air/fuel ratios can also be displayed on a computer, tablet or smartphone via Bluetooth. VR7 at pin 43 (ANC5) sets the coefficient for AF1, while VR8 at pin 42 (ANC4) sets it for AF2. VR7 is adjusted so that the voltage at TP7 is one-tenth of the desired air/fuel ratio for lambda = 1.0 for AF1. So for a 14.7 stoichiometric air/fuel ratio, VR7 is adjusted for 1.47V. Similarly, VR8 is set for the AF2 air/fuel ratio value. For example, for a 15.5 air/fuel ratio for lambda = 1, VR8 is adjusted for 1.55V. Screen 1 shows the display on a computer via Bluetooth with a setting of 15.5:1 and a lambda of 1.0. Screen 2 shows the Android version but with at a lambda of 1.02 and 15.1:1 Air/ Fuel ratio. The VR7 and VR8 trimpots can be adjusted for different Air/ Fuel ratios. The software can also display lambda even if they are set for other values. It can even display AFR and lambda simultaneously. The lambda display has the decimal point moved left one digit compared to the air/fuel display version. These displays via Bluetooth work on recent Windows versions on a PC and run as a standalone executable file. Our prototype is run using Windows 11. As Processing is supported on macOS, the software should work on a Mac too, although we have not tested it. For Android, Processing does not Screen 1 (left): the Processing app can be made to run on Windows, Linux or Mac systems and shows the AFR and lambda values simultaneously. Screen 2 (right): the Android version, written in MIT App Inventor, is similar. You just have to choose the Bluetooth device and connect to it, after which you get live AFR and lambda displays. 76 Silicon Chip Australia's electronics magazine siliconchip.com.au have the required Bluetooth serial support, but MIT AppInventor does. So we have produced an app using AppInventor that mostly does the same job. We will make an APK file available, along with the source code. Dual panel meter display A multimeter output is also provided that shows the lambda value (as a voltage) and a current flow that can be displayed on a V/A panel meter. For this output, filtered PWM signal from the PWM2 output is buffered by op amp IC3b. The multimeter output is then taken via a voltage divider comprising trimpot VR9 and the 10kW resistor to ground. VR9 is adjusted for an output of 1V for a lambda of 1.0. For the current meter, IC3b sources current through a 330W resistor and trimpot VR10 (for calibration) to a shunt resistor. This 1W shunt resistor replaces the low-value shunt in the panel meter so that we don’t have to supply a huge current to get an appropriate reading. The meter can then show the lambda value, reading 1.00 when the lambda value is 1. This calibration is done with jumper shunt JP2 at the RC6 digital input of IC1 (pin 44). With JP2 shorted, the software within IC1 sets its outputs to show a lambda of 1 and a corresponding air/fuel ratio at a lambda of 1. The air/fuel ratio values produced at MV+ are also set with this calibration shunt. With JP2 in, the narrowband output produces 450mV (no adjustment is necessary). For the MV+ output, the voltage is adjusted to show the required air/fuel ratio using VR5 for the AF1 selection and VR6 for the AF2 selection (with JP3 in or out). So for a 14.7 air/fuel ratio at a lambda of 1, the voltage at MV+ is set to 14.7V, while MV+ is set at 15.5V for an air/ fuel ratio of 15.5 at lambda = 1. Sensor control Op amp IC4d is connected as a differential amplifier to monitor the voltage across the paralleled 62W and Rcal resistors. It operates with a gain of 25.45, as set by the 560kW and 22kW feedback resistors. The 3.3nF feedback capacitor rolls off high frequencies and prevents amplifier instability. IC4d’s output is referenced to the Vs/Ip voltage (at +3.3V) by the 560kW resistor between its pin 12 input and the Vs/Ip line, via op amp IC4c. As a result, when there is 0V across the siliconchip.com.au 12 multi-turn trimpots allow adjustments detailed in the text to be made with the case lid removed. 62W resistor, IC4d’s output sits at 3.3V. Sensor cell voltage Op amp IC4a monitors the sensor cell voltage (Vs). When Vs is at 450mV, IC4a’s output is 2.5V. To achieve this, trimpot VR4 provides an offset voltage that’s buffered by op amp IC4b. The result is that IC4a’s output can swing symmetrically above and below 2.5V to drive IC1’s ANA7 input (pin 30). This voltage swing is an exaggerated (by 4.7 times) measurement of any variation above or below 450mV from the sensor cell. The reference current applied to the sensor cell is derived via a 62kW resistor between the +5V supply rail and the Vs terminal of the sensor cell. When the controller is running and measuring correctly, the Vs terminal is at the Vs/Ip voltage of 3.3V plus the 450mV of the sensor cell, ie, 3.750V. So there is 5V – 3.75V = 1.25V across the 62kW resistor and 20.2μA flows (1.25V ÷ 62kW). The actual current does not affect the accuracy of lambda measurement unless the current is reduced to near zero or is increased above 40μA. Engine start detection Trimpot VR13 sets the threshold voltage for detecting when the engine has started by monitoring the battery voltage. It is measured at the AND4 analog input of IC1 (pin 2) via a 20kW and 10kW voltage divider connected between the +12V input rail and 0V. This divider reduces the applied voltage by two-thirds and results in a Australia's electronics magazine maximum of +5V at the AND4 input for a battery voltage of 15V. Typically, a 12V lead acid battery is below 12.9V when the engine is off but rises above 12.9V when the engine starts and the alternator begins charging it. So the battery voltage is compared with the threshold voltage at TP17 (AND2 of IC1), as set by VR13. This threshold voltage can be set anywhere from 0-5V, corresponding to a battery voltage range of 0-15V. The TP17 voltage is set to 1/3rd the required engine-started battery voltage. For example, for a threshold of 13V, TP17 should be at 4.33V (13V ÷ 3). When the wideband controller is used as a portable air/fuel ratio measuring instrument, TP17 will need to be adjusted to slightly less than 4V so the controller will begin operation with a 12V DC supply. This ensures that the sensor is heated when power is first applied. However, it also means that the sensor must be protected from moisture ingress and physical shock when not in use. Driving the heater Mosfet Q1 drives the sensor’s heater with a voltage derived from a 122Hz PWM signal delivered from IC1’s PCB Dimensions Error The parts list last month stated the PCB measures 160.5 × 98.5mm and we priced it at $15 + postage on the shop page. The PCB is actually 103.5 × 63.5mm and as a result, we have changed the price to $10 + postage. May 2023  77 The HC-05 Bluetooth module shown enlarged for clarity. Normally the module is supplied with the heatshrink pre-attached. PWM6 output (pin 5). The heater current flows through the Mosfet and is monitored via the AND6 input at pin 4, ie, by monitoring the voltage across the 0.1W 3W resistor that’s low-pass filtered by the 22kW resistor and 10μF capacitor. The Mosfet current is measured during the sensor heating period, to detect if the sensor is connected and, specifically, if the heater is connected. It also checks for an over-current condition, such as a short circuit, although the fuse would probably blow in that case. The heater is switched off under fault conditions and the status LED (LED1) shows the fault. It’s driven from the RA3 digital output of IC1 (pin 22) via a 470W current-limiting resistor. It lights dimly when the sensor is heating and then flashes rapidly once the operating temperature is reached. It flashes more slowly if there is a sensor error. Pressure sensing The pressure sensing circuit comprises the pressure sensor plus trimpots VR11 and VR12. These trimpots connect to analog inputs AND5 (pin 3) and AND3 (pin 41), respectively. With a 5V supply and when there is equal pressure on each input port, the output from the sensor sits at 500mV. Its output rises when pressure is applied to the positive pressure port and varies by about 50mV/kPa. With the available 4.5V output range from 500mV to 5V, the maximum pressure measurement is 90kPa (900hPa). The Bosch pressure sensor. 78 Silicon Chip The pressure sensor we use is a particulate filter differential sensor designed to detect when the particulate filter for a diesel engine is clogged. It detects the pressure differential between the input and output of the filter; the higher the pressure difference, the more the filter is clogged. As we are using it to measure the exhaust pressure, only one input is needed; the other port is blocked off. VR11 is used to adjust the pressure sensor calibration to 25mV/kPa. For the sensor used, this means setting the trimpot to mid-way, reducing the 50mV/kPa output to 25mV/kPa. The no-pressure output of 500mV is also reduced to 250mV. VR11 is included so that another type of pressure sensor can be used, provided it has no less than a 25mV/ kPa output. For outputs over 25mV/ kPa, such as the one we use, VR11 reduces the output level applied to AND3 to set the correct calibration. VR12 is to set the voltage offset from the sensor, as measured at the AND5 input. That’s so that IC1 can calculate the pressure based on the fact that the voltage rises from the no-pressure voltage at 25mV/kPa. IC1 then makes the required compensation of Ip variation with pressure for up to 12% for lean values and 9% for rich values. These corrections are in accordance with the graph shown in Fig.8 from last month. In practice, VR12 is set so that the voltage at TP12 is the same as at TP11 with no pressure differential across the sensor inputs. The pressure sensor is set up by plugging (blocking) one of its differential air inlets to allow the sensor to work as an absolute pressure sensor rather than as a differential sensor. This is best done when the sensor is at sea level, at the standard air pressure of 1013hPa. If the input is plugged at higher altitudes, the sensor output will be referenced against the lower pressure in the plugged inlet, increasing the effective sensor offset. VR12 can also be used to counter this effect. Air pressure reduces by 11kPa per 1000m above sea level. Since the calibration is for 25mV/kPa, reduce the voltage by 27.5mV per 100m above sea level. This is suitable for altitudes up to about 900m, where the pressure versus altitude becomes non-linear. If the pressure sensor is not used, Australia's electronics magazine the AND5 input will be held low via VR11, indicating to IC1 that the sensor is not connected. No pressure corrections will then be made. The Bluetooth module The HC-05 Bluetooth module connects to the Tx (pin 10) and Rx (pin 11) of IC1 at the module’s serial Rx and Tx pins, respectively. The Rx input to the HC-05 module is supplied with a reduced voltage from the Tx output of IC1 via a resistive attenuator. This reduces the 5V output from the Tx pin to 3.3V. Some HC-05 modules are not 5V-tolerant and so require this attenuation. Data is sent to the Bluetooth module using 8-bit data, no parity and one stop bit at 9600 baud. The six data digits for the air/fuel ratio and lambda are sent in ASCII format with a line feed character at the end. Switch S1, connected to IC1’s RB1 digital input (pin 9), is included in case the HC-05 module requires manual pairing. When held closed during power-up, IC1’s RB4 digital output (pin 14) drives the EN (enable) input to the module low, allowing pairing with a Bluetooth receiver. The module we used did not require this procedure. Power supply Power for the circuit comes from the 12V vehicle battery. The +12V rail is fed via fuse F1 and applied directly to one side of the oxygen sensor heater (via H+ at Vbatt) and the input to REG2 (LM2940CT-12). REG2 can handle a reversed supply without damage; however, REG1 (the LM317T adjustable regulator) cannot, so power goes to the latter via reverse polarity protection diode D1. Fuse F1 will blow if the sensor is connected and the supply polarity is reversed. That’s because there would be a low-resistance current path through the heater element and the body diode in Q1. Trimpot VR1 allows REG1’s output to be set to precisely 5.00V, as this supply is used as an accurate reference voltage for the circuit. This rail also supplies microcontroller IC1 and dual op amp IC4. In contrast, dual op amp IC3 runs from +12V and -3V rails. That is mainly so that the pump current op amp (IC3a) can provide the required current right up to the 0V and 5V siliconchip.com.au supply rails. Even though the op amps are rail-to-rail types, they can’t supply much current at voltages right near their rails. Similarly, IC2 has a 33V positive supply so that the output from IC2a can deliver a voltage to indicate the air/fuel ratio at lean values, where the required voltage is well above 12V. Negative supply generation The -3V supply is derived using a voltage inverter that inverts the +5V supply, while the +33V supply is from a voltage tripler that increases the 12V supply by almost a factor of three. The -3V supply is generated by transistors Q2 & Q3, diodes D2-D4 and their associated capacitors. This circuit is driven by a pulse width modulated output of IC1 (PWM3) that delivers a 31.25kHz 5V peak-to-peak square wave signal. Q2 & Q3 buffer this signal and drive an inverting diode pump circuit consisting of D2 & D3 and two 10μF capacitors. The square wave at the emitters of Q2 and Q3 ranges from about 0.6V to 4.4V; it is not the full 0-5V swing due to the base-emitter voltage drop of each transistor. When Q2 is on, the 10μF capacitor connected to it charges via diode D2 to ground. The total voltage across the capacitor is 3.8V (4.4V – 0.6V). When the PWM3 output goes low (0V), transistor Q3 switches on, pulling the positive side of the capacitor to about 0.6V. The opposite side of the capacitor is pulled negative, causing diode D3 to conduct and charge the second 10μF capacitor to a negative voltage. This produces a negative supply rail of around -3V. We don’t get a full -5V SC6721 Kit ($120 + postage) Includes the PCB and all the parts that mount directly on it; the microcontroller comes pre-programmed (the Bluetooth module is also included). You need to separately purchase the oxygen sensor, case, wiring, fuse holder, off-board connectors (including those for the O2 sensor) and optional parts like the pressure sensor and LED display. because of the transistor and diode voltage drops. Diode D4 clamps the negative rail, preventing it from going positive by +0.6V when the negative supply generator is not working, such as when the power is first applied and IC1 hasn’t started generating the square wave. Zener diode ZD3 limits the total voltage across IC3 to 15V. The 15V voltage limit is needed as the LM6482 has a total supply limit of 16V. So when the positive supply is 12V, as supplied by REG2, the negative supply is clamped at -3V. The alternative recommended IC for IC3 is the OPA2171, which can handle supply rails up to 36V in total. In that case, ZD3 could be left out. 33V supply generation The 33V supply for IC2 is from the voltage tripler driven from the PWM4 output of IC1 (pin 8). This produces a 31.25kHz square wave that drives a buffer comprising transistor Q4, Q5 and diode D5. When the PWM4 output is low, transistor Q4 is off, so its collector is pulled toward the 12V supply via the 1kW resistor. As this point also connects to the base of Q5, Q5 is on and its emitter is pulled up to around 11.4V. When the PWM4 output goes high, Q4 switches on and pulls its collector (and thus Q5’s base) down to around 0V. This means that Q5 is off, but D5 conducts, so its anode voltage drops to about 0.3V. Diodes D5-D9 are schottky types that have lower forward voltages than standard diodes. The resulting 11.3V to 0.3V swing at the emitter of Q4 and anode of D5 drives the voltage tripler circuitry via diodes D6, D7, D8 and D9 and the series of 1μF capacitors. ZD2 clamps the output voltage at 33V. Microcontroller details Pin 18 of IC1 is the MCLR reset input. It’s pulled high via a 10kW resistor and ensures that IC1 is reset on power up. The MCLR input, the clock (pin 16), the data line (pin 17) and the 5V and ground supply connect to an in-circuit serial programming header (ICSP) to allow IC1 to be programmed. The header isn’t required if the IC is already preprogrammed, such as the one included in our short-form kit. Link setting When installed, jumper JP1 ties IC1’s RC7 (pin 1) input low. This selects a test mode for checking that the sensor impedance is correct (300W). In this mode, the narrowband output produces a value corresponding to the sensor cell’s impedance. Since this impedance depends on the sensor temperature, it’s a good way to check whether that part of the control circuit is working and verify that the sensor is not being overheated by exhaust gas when installed in a vehicle. As mentioned earlier, when jumper JP2 is shorted, the WFMD produces fixed outputs at lambda = 1 for calibration. Next month, we will describe the construction procedure, how to set up and calibrate the WFMD and install the sensor in a vehicle’s exhaust system, as well as how to install and use the SC Bluetooth app. We replaced the narrowband sensor used in a 2000 VW Caravelle with the Bosch LSU4.9 wideband sensor and connected the narrowband ‘S’ curve output of the WFMD to the vehicle’s ECU to simulate a narrowband sensor signal. The yellow trace is the wideband output and cyan the narrowband output. It cycles between rich and lean about once every two seconds because the ECU is adjusting the fuel injector duty cycle based on the narrowband output. The wideband signal doesn’t visibly vary much because it’s only ranging over 0.98 to 1.02 lambda, as shown in the video at siliconchip.au/Videos/WFMD (taken from a computer using the Bluetooth interface). siliconchip.com.au Australia's electronics magazine May 2023  79 Songbird By Andrew Woodfield Here’s a decades-old design brought up to date in a new package and made to appeal to beginners as well as experienced builders. It’s quick and easy to build and a great project if you’re new to electronics. W hen the festive season or birthdays approach, those interested in electronics often look for a small, easy-to-build project to give as a gift. Something with flashing lights or a variety of sounds has universal appeal, especially for our (grand)children. Helping a beginner to build one of these is the perfect way to spark an interest in the hobby. The problem is identifying a suitable design. During a recent search, I came across an “electronic canary” designed by Ron de Jong, published in Electronics Australia way back in May 1981. Unfortunately, the 74C-series CMOS chip used in the original design is not as widely available as 74HC-series devices. Also, the original design used a large square PCB mounted in a very large plain rectangular plastic box with a mostly bare aluminium front panel. I felt it lacked the visual appeal to capture the imagination of today’s younger audience. This revision was my solution. Along with migrating the circuit to the 74HC-series CMOS family, I also redesigned the printed circuit board (PCB) into a more compact and attractive bird shape – something between an overfed festive budgie and a kookaburra! Modern PCB manufacturing provides a choice of PCB solder mask colours. I chose purple, but you could also go with something like green, The ‘inspiration’ for the Songbird project came from the May 1981 edition of Electronics Australia. The image shown is the lead photo used for that article. 80 Silicon Chip Australia's electronics magazine yellow or red (after all, it was initially a “canary”). Contrasting with the colour-coded bands of the resistors on the PCB, the overall effect is bright and cheerful. The double-sided PCB design also makes it much easier to build than the original design. I removed the original large and costly 8W speaker and its driver transistor in favour of a modern, inexpensive piezo speaker. Mounted on the rear of the PCB, it produces a bright sound without driving parents to utter despair. The original used a somewhat expensive 9V battery, while a pair of inexpensive AAA cells power my new version. The new 3V supply also significantly reduces the current draw to under 2mA. What makes it sing? The Songbird consists of two almost identical sets of three coupled oscillators, ie, circuits that produce a continually changing voltage level. Each oscillator uses one of the six CMOS schmitt-trigger inverters inside the 74HC14 integrated circuit (IC). Fig.1 shows the basic oscillator circuit used in each case. siliconchip.com.au Fig.1 (above): the Songbird uses six oscillators, all based on this simple RC (resistor-capacitor) oscillator configuration. Fig.2 (right): these three waveforms are created by each set of three schmitt-trigger inverter based oscillators. The inverter (triangle) produces a low output voltage when its input voltage is high and vice versa. Connected to it are a resistor, ‘R’, and a capacitor, ‘C’. The values of C and R vary in each oscillator. When power is switched on, capacitor C is discharged, and the inverter input is at ‘ground’ potential (0V, or logic ‘low’ level). As a result, the output of the inverter is near +3V (a logic ‘high’ level). The voltage across capacitor C begins to rise as current from the high level at the inverter output flows via resistor R. When the voltage across C rises above the schmitt-trigger low-to-high transition voltage (about 1.5V in this case), the inverter input recognises that the input has gone from a logic ‘low’ to a logic ‘high’. It immediately changes the inverter’s output to a logic ‘low’ voltage, almost at ‘ground’ potential or 0V. The voltage across capacitor C starts to fall as current flows from the capacitor back to the low-level output via resistor R. When the input voltage falls below the schmitt-trigger high-to-low transition voltage (about 0.7V), the inverter input voltage is detected as a low, and output suddenly switches to high. The whole cycle then repeats. Over many such cycles, the result is a sawtooth voltage at the input pin varying from 0.7 to 1.5V, and a square wave at the output ranging from almost 0 to 3V. The frequencies of these waveforms are identical and proportional to siliconchip.com.au the product of the values of resistor R and capacitor C (the ‘time constant’). The basic bird sound is made from two pairs of three of these oscillators coupled together. In each tri-­oscillator group, one sets the basic timing, the second creates the chirp, while the third makes the tone of the bird sound. Other components around each oscillator modify and combine these three to produce the final sound. The resulting waveforms are shown in Fig.2. At the top of Fig.2 is the timing oscillator, in the middle is the chirp oscillator and at the bottom is the note oscillator. The full Songbird circuit is shown in Fig.3. In each oscillator, a series diode/ resistor combination placed in parallel with resistor R results in an asymmetric square-wave shape by changing the resistance depending on whether the capacitor is being charged or discharged. Different capacitor and resistor values in each set of three timing-­ chirp-note oscillators produce two slightly different bird sounds. These are combined by using each The basic version of the Songbird uses a simple unetched PCB as the base. If using the battery box with an integral switch, the base will need to be slightly wider (63mm) as the box is longer than the holder shown here. Still, it saves you from having to mount and wire up the switch. Australia's electronics magazine May 2023  81 Fig.3: the full circuit of the Songbird replicates the oscillator configuration shown in Fig.1 six times. This is convenient as IC1 contains six inverters, so only one chip is needed. Each triplet of oscillators uses a different set of feedback components to produce different frequencies. They are ganged up via resistors and capacitors, ultimately feeding the piezo speaker together via connector CON2. output to drive one side of the relatively high-impedance piezo speaker, which produces the final desired bird sounds. The circuit is powered by a battery, shown at upper-right in Fig.3, comprising two 1.5V cells in series to produce 3V. It is connected to the circuit via switch S1, which acts as a power on/ off switch. A 100μF capacitor stabilises the battery voltage so that it does not vary in the short term as the oscillators draw varying currents. Building the Songbird As this is an ideal beginners’ project, the following description is primarily written for those with limited experience. Children from around nine or ten years of age can build it (with help). However, it’s equally suitable for those interested in building a little project that is just a bit different. Simply put, you can never be too old to build the Songbird! Children and beginners will need help from a more experienced builder, given the inherent risks of a hot soldering iron and other possibly dangerous tools like side-­cutters. The instructions assume it will be built in four stages, each taking 82 Silicon Chip between 20 and 45 minutes. You might prefer to make it in several shorter 10-to-15-minute bursts to better match a younger child’s concentration. For the more experienced, you can probably build the whole thing in about 1½ to 2 hours. Still, there’s no rush. The Songbird will happily wait to burst into song until you’re finished. You will likely make fewer mistakes if you take your time. Check each part before soldering and enjoy the relaxed pace of the construction process. Some tools you’ll need include: 1 A 15-25W soldering iron with a fine to medium tip. Keep this clean by carefully wiping the tip periodically on a damp rag or sponge. 2 0.5-1.0mm fine rosin-cored solder. If this is your only project, a 15g ‘hobby tube’ will probably be enough 3 Sharp pair of small side cutters. Other useful tools include: 4 Fine needle-nosed pliers or a component bending jig like Jaycar Cat TH1810 or Altronics Cat T1495 – these will help you bend the component leads. 5 A soldering iron holder – it helps you to avoid accidental contact with the iron’s hot tip! A good Australia's electronics magazine soldering station will come with one. 6 A ‘solder sucker’ desoldering tool and/or solder wicking braid – these help you to remove solder if you get it in the wrong place or incorrectly place a part and need to remove it (that can happen to anyone). 7 A multimeter – you might find this helpful for checking resistor values, checking battery voltages and testing for shorts and open circuits. They start under $10 (Jaycar Cat QM1500, Altronics Cat Q1053B)! Find a clear space to build the Songbird, such as a kitchen table, with plenty of light. Also, ensure you have good ventilation because soldering will create some fumes. Place a cloth or a layer of newspaper (or similar flat disposable material) over your working area to avoid marking the tabletop with your tools, the PCB or molten solder during assembly. A helpful way to handle the parts during construction is to place them in a small plastic tray, say 300mm × 200mm, on one side of your workspace. Construction step #1 (resistors) The location for each resistor is siliconchip.com.au Fig.4: this shows the shape of the Songbird PCB and where each resistor is soldered. The colour bands are shown for four-band (5%) resistors; see the parts list for the equivalent five-band codes. It’s still a good idea to check them all using a DMM set to measure ohms, as some colours can be easily confused (eg, red & orange). shown in Fig.4. It’s usually easiest to install the resistors in groups. Double-­ check the value of each resistor using its coloured bands before fitting (or even better, verify the value with a DMM set to measure ohms) because different resistors have very similar bands (eg, 1kW, 10kW and 100kW). Your parts supplier may only have (smaller) 1/8W resistors or (more precise) 1% tolerance resistors, which will work just as well. 1% resistors have five bands rather than four. See the table in the parts list, which shows how they vary. You will need to bend the leads of the resistors into a U-shape so you can insert them into the pads on the PCB, as shown in Fig.5(a). You can do this with your fingers or pliers, but it’s more precise to use a lead-bending jig (available at low cost from stores like Jaycar and Altronics), as it will form the bends precisely the right distance apart. Then, insert the resistor as shown in Fig.5(b). Solder the leads, making sure to form a shiny fillet like in Fig.5(c), then trim the excess leads using side-cutters at the height indicated by the dashed line. Protect your eyes when doing Fig.5: each resistor should be (a) bent to shape, (b) placed down on the PCB, soldered, and then trimmed with side cutters (dotted line height) to produce the result at (c). siliconchip.com.au this, as the cut leads can be sharp and will fly off if you don’t hold them while cutting. Note that there are two ways to insert each resistor but the circuit will work either way. Still, it’s neater to place them all in the same orientations, as in Fig.4. Construction step #2 (diodes & capacitors) Next, fit the six diodes as shown in Fig.6. These are all the same type, but your diodes may have a slightly different body colour to those shown here. Their size is exaggerated for clarity in Fig.6; the important thing is that, in each case, the black stripe on the end of the glass body must face down or to the right as shown. Bend each diode’s leads as you did for the resistor. When you insert it, make sure to align the diode’s black band with the band printed on the PCB overlay. Solder and trim the leads in the same way as for the resistors. Fig.6: this diagram will help you to fit the diodes and the capacitors on the Songbird’s PCB. The ceramic capacitors are not polarised and can go in either way around. However, the electrolytic capacitors must have their longer leads inserted in the pads marked with a + (the stripe on the can indicates the opposite, negative lead). Similarly, the diodes must be fitted with the cathode stripes facing as shown. Australia's electronics magazine May 2023  83 Parts List – Songbird The ‘basic’ version of the Songbird. The main PCB is soldered along its base to a single-sided unetched PCB. The battery holder and slide switch are also mounted to the unetched PCB. Next, fit the four ceramic capacitors, shown in yellow in Fig.6. Two have the same value. Take care to place the correct part in the right location, although they are non-polarised, so it doesn’t matter in which of the two possible orientations you fit them. The PCB silkscreen overlay shows the value of each capacitor to help you. Ceramic disc capacitors may be marked in various ways. The most common markings are shown in Fig.6. After fitting each component, solder and trim the leads similarly to before. Next, fit the three smaller axial electrolytic capacitors, which are mounted on the top side of the PCB. They come in metal cans with a plastic covering 1 double-sided purple, green, yellow or red PCB coded 08103231, 61 × 75mm 1 2×AAA switched battery box with flying leads (BAT1+S1) OR 1 2×AAA battery holder and toggle or slide switch (BAT1/S1) 1 27mm diameter piezo loudspeaker (SPK1) 1 52 × 45mm (63 × 45mm if using battery box) unetched copper-clad PCB (optional; stand for basic version) Resistor Colour Codes Semiconductors 1 74HC14 hex schmitt-trigger inverter, DIP-14 (IC1) 6 1N4148 75V 200mA diodes, DO-35 (D1-D6) Capacitors 1 220μF 16V radial electrolytic 2 100μF 16V radial electrolytic 2 10μF 16V radial electrolytic 2 1nF 50V ceramic 1 680pF 50V ceramic 1 470pF 50V ceramic Resistors (all 1/4W axial, 5% or better) 2 1MW 2 680kW 1 470kW 3 330kW 2 100kW 2 68kW 2 47kW 2 39kW 2 10kW 2 1kW except at the top. Electrolytic capacitors are polarised, meaning you must orientate them correctly. The negative lead is marked by a stripe on the capacitor body, while the overlay diagram indicates where the longer positive lead is inserted. Once they are in the right places and have the correct orientations, solder each capacitor and trim the leads. The two larger electrolytic capacitors go on the rear side, allowing the Songbird’s eye to be more clearly seen. Mount them last. Construction step #3 (the integrated circuit) You must fit the 74HC14 CMOS IC to match the pattern shown on the white PCB overlay. One end of the IC is marked by a notch in its body (some ICs have a divot or dot in the nearby corner instead). This end goes closest to the Songbird’s eye, as shown in Fig.8. Before trying to fit the IC, it’s helpful to slightly bend each row of IC pins until they are close to parallel. Gently roll each side of the IC towards the ends of the pins on a hard flat surface, as shown in Fig.7, so that the IC pins lie parallel (or close to it). You can also buy a tool to do this (again, check Jaycar & Altronics), which is easier to use, but the flat surface method works if you’re careful. Now fit the IC into the PCB as illustrated in Fig.8 and solder all the pins. You don’t need to trim the pins after soldering, as they should only just project through the other side of the PCB. Construction step #4 (speaker & battery) Fig.7 (above): bend the IC pins carefully to be approximately parallel before inserting them into the PCB. It’s better to use a lead straightening tool, but easy enough to do it with a flat surface as long as you don’t apply more force than needed. There are two ways to complete the Songbird. You can use a simple square PCB for the base. This version is quick and easy to build. Alternatively, you can create a more elaborate birdcage and base. That will take more time, but it gives a more attractive finish to the project. Fig.8 (right): the 74HC14 hex inverter IC must be fitted with its notch (pin 1 marking) matching the pattern printed on the PCB, as shown here. Option 1 – simple PCB base The photo at upper left shows the 84 Silicon Chip Australia's electronics magazine siliconchip.com.au The 3D-printed piezo speaker mount The piezo speaker recommended is a low-cost 27mm diameter part commonly used in greeting cards and small toys. They are readily available from a variety of suppliers. Slightly more expensive piezo speakers are made complete with a thin pressed metal enclosure to form a resonating chamber, but they are harder to mount to the Songbird. The 3D-printed holder used here has three benefits. It simplifies mounting (just use glue!), the sound is significantly improved, and it’s all quite cheap and easy to do. It’s surprising the difference this simple piezo mount makes to the overall sound volume. The piezo sits on the circular lip of the mount facing outwards. A tiny drop of super glue holds the piezo to the mount. It’s also possible to make a 5-10mm high 27mm diameter tube speaker mount using rolled-up paper. Produce a wall thickness of about 1mm, gluing the paper with PVA or similar glue to give it a little rigidity. Glue the circumference of the piezo speaker to the top surface of this tube with a drop of super glue, then hot glue the assembly into place on the rear of the PCB. Fig.9: this simple 3D-printed speaker mount improves the sound quality and simplifies construction. basic version with the PCB mounted to a single-­sided, unetched 52 × 45mm PCB base by soldering a few spots along the lower edge of the Songbird PCB. The result is surprisingly robust. The double AAA-cell battery holder and slide switch are then mounted directly to this blank PCB, the former with a couple of drops of epoxy glue and the latter by soldering three of the unused lower tags of the slide switch to the blank PCB base. Note that kits will include a battery box with an integral switch, simplifying construction somewhat. The kit will also have a double-sided tape pad that you can use to stick that box to the base very easily and quickly. Since the battery box is a bit longer than a simple battery holder, it would be best to use a 63 × 45mm unetched PCB for the stand in this case (not included in the kit). Alternatively, you could use hot melt glue or silicone sealant to attach the Songbird PCB to the side of the battery box. Just make sure you can still open it to replace the cells! The piezo speaker can be mounted on the rear of the main PCB using a 3D-printed speaker mount (see Fig.9) and a couple of dabs of hot glue. You could print this yourself if you have a 3D printer, although it will be included in the kit. STL files for all the 3D-printed items used in this project are available for download from the Silicon Chip website. siliconchip.com.au The ‘bird cage’ version of the Songbird uses a 3D-printed base and some wires to act as a ‘cage’. The speaker is attached to the rear of the PCB using the mount from Fig.9. The two piezo speaker wires may be connected either way around to the PCB at the two points marked “Piezo” on the overlay, as shown in Fig.10. You can trim the wires slightly if they are too long before soldering them in place. These wires may be almost any colour, and some can be pretty delicate, so a little care is required. Finally, add the battery and switch wiring; the switch is not required for the battery box included in the kit, as it is already integrated into the box. In that case, you just need to connect the two wires from the box to the PCB but watch the polarity; the red wire must go to the terminal marked + on the PCB. Option 2 – bird cage I designed a 3D-printed base for the prototype. Those with a lathe may prefer to create a more elegant base from suitable timber. Alternately, a careful hunt around the supermarket shelves may locate a suitable 15mm-tall, 70mm diameter screw-on plastic jar lid. The battery holder and switch can then be mounted in this base. I used a toggle switch for this, rather than a slide switch, because it’s easier to mount on a curved surface. The Fig.10: the battery and piezo speaker wiring are shown here. This diagram also shows the overlay markings for these connections to help you identify them. If your battery holder has an integral switch, you don’t need the external switch; just run the red wire from the battery holder straight to the pad marked + on the PCB, parallel to the negative (black) wire. Australia's electronics magazine May 2023  85 Fig.11: if building the birdcage version, glue the battery holder into the base before installing the switch and completing the wiring. Songbird is then mounted on the base using two small PCB off-cuts measuring about 3 × 6mm. These are soldered on the lower edge on the rear of the main PCB, separated by a gap of about 10mm. This method allows the Songbird to be mounted into the slot in the base and then adjusted from side-to-side in the slot to centre the Songbird in its cage. The gap in the slot is used for the wiring to the switch and battery. The wiring details inside the base are shown in Fig.11. The piezo speaker is mounted in the same way as the basic version (Option 1). The battery and speaker wiring to the PCB is the same as shown in Fig.10. If you prefer that the speaker is out of sight, there is enough space in the base for it to be glued there using the 3D-printed speaker holder. However, the bird sounds will be less audible. The birdcage is made from 18-gauge (1.2mm diameter) galvanised wire and a 20mm diameter piece of tinplate. You can obtain the galvanised wire from most garden centres or hardware Fig.13: The 3D-printed sign frame (28 × 18mm) for holding the Fig.12 signs. 86 Silicon Chip stores. I cut the circular piece of tinplate from a discarded tin can. It’s easiest to begin by unrolling about a metre of wire from the wire roll. Get this as straight as possible by holding one end of the wire in a vise and pulling on the other end with a pair of heavy-duty pliers. Modest force is sufficient. Then cut eight 105mm lengths from this straight piece. Using a piece of waste timber or plywood, place these wires radially around the circular tinplate as evenly as possible. Tape them in place temporarily using short pieces of painter’s masking tape. Once everything is nicely aligned – the tape really helps with this – solder the wires to the circular tinplate. The timber insulates the soldered wire and plate and protects your work surface. Bend each wire into the final birdcage shape by hand. The wire is very easy to bend yet holds its shape well. You can then ease the ends into the eight holes in the base of the 3D-printed base or your timber base. To ensure a good fit, you may need to drill out each of the eight holes in the 3D-printed base. This depends on the accuracy of the 3D printer. These 1.2mm diameter holes are evenly spaced on a 65mm diameter circle centred on the 70mm diameter base for those making up their own base from other materials. Add a small drop of epoxy or hot glue inside the base to hold each of the wires in place. It all sounds complicated, but in Australia's electronics magazine Fig.12: the optional signs for the birdcage version of the Songbird. You can download the sign artwork and 3D printer (STL) files from the Silicon Chip website. practice, it takes surprisingly little time and effort and gives a pleasing visual finish to the project. You can add the optional “Please Do Not Feed The Bird” sign. This, and the equally optional extra sign for the other side, can be glued to the front and back of a piece of card or onto a 3D-printed frame (the latter is also available as a download). This can be glued to a suitable location on the Songbird’s cage. Operation Turn on the Songbird’s switch and the Songbird will burst into song almost instantly. The prototypes I made were joined by several additional copies as budding builders added their own efforts. The chorus of the Songbird birds produced a fantastic sound. Parents will be “delighted” to learn that battery life is at least six months of regular use! If you want to adjust the Songbird’s sound, changing the value of the 330kW and 470kW resistors in series with the 1nF capacitors will have the SC most significant impact. SC6633 kit ($30 + postage) This mostly-complete kit includes the main PCB (purple, green, yellow or red – please specify) along with all the parts that mount on it, plus the piezo, 3D-printed piezo mount and switched battery box. All you need to add is the base/stand. siliconchip.com.au 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. An even more flexible Flexitimer After acquiring a Companion Rover 40Ah Li-ion power station to power a camping fridge, I found that once the internal battery became fully charged, it would discharge even though it was connected to an external power source. After reading the manual, I found, “The power station will automatically turn off when it is fully charged”. Disconnecting the external power source struck me as a bit unusual, as leaving the unit plugged into the mains adaptor would eventually result in a flat battery. Further testing over several days confirmed the same result, although I found that disconnecting then Circuit Ideas Wanted siliconchip.com.au reconnecting the external power occasionally would restart the charging cycle. So I purchased a Flexitimer kit from Jaycar (www.jaycar.com.au/p/ KA1732) to generate a 5-10 second pulse roughly once per hour to reset the charging cycle. However, I discovered that the timer, as designed, has a 50% duty cycle, giving me one hour on and one hour off, which is not what I had in mind! John Clarke published an improved version of the Flexitimer circuit in the Circuit Notebook (CNB) section of the April 2010 issue that added a restart button (siliconchip.au/Article/112). I took his version and added a NAND gate made of discrete components (Q3 & Q4) to allow the easy selection of time intervals, which works a treat. Switch S1 determines when the relay switches on, while S4 determines how much later the relay switches off (in this case, just one clock pulse later). Switches S1 and S4 are separate 12-way single pole switches, however a simple wire soldered from one pad of IC2 to Q3’s base resistor is sufficient if you don’t wish to add another switch. I added another SPDT switch, S3, which allows the circuit to be switched between being an interval or one-shot timer. Chris Sweet, Carlingford, NSW ($80). Got an interesting original circuit that you have cleverly devised? We will pay good money to feature it in Circuit Notebook. We can pay you by electronic funds transfer, cheque or direct to your PayPal account. Or you can use the funds to purchase anything from the SILICON CHIP Online Store, including PCBs and components, back issues, subscriptions or whatever. Email your circuit and descriptive text to editor<at>siliconchip.com.au Australia's electronics magazine May 2023  87 Jaycar TS1440 soldering stand adaptor This contribution does not involve a circuit but is useful nonetheless. I bought a Jaycar TS1440 soldering station and am very pleased with it. However, the part that holds the soldering iron does not look like the one in the catalog photo; it is probably a more recent, improved version. The case containing the transformer and controller has grooves in it; the older stand might have fitted into those grooves. The new one doesn’t. I often tinker with 3D printing, so I decided to make an adaptor for the new soldering iron stand. I designed it using OpenSCAD, which is free 3D design software. The resulting STL files are available for download from siliconchip.com.au/Shop/6/148 It is in two parts. The part I call “FloorOne” fits into the slots on the top of the transformer case, and I glued it there using clear neutral-cure silicone sealant. The part I call “FloorTwo” sits on top of FloorOne and is held there with eight of the tiny ceramic magnets Jaycar sell: their Cat LM1622 is a kit of four, so two sets give eight magnets. Four magnets fit into the bottom of FloorOne, while the other four fit into the top of FloorTwo; I also secured the magnets with silicone sealant. Two magnets per floor might be enough; that would reduce the total cost by about $10. It is necessary to get the magnets’ polarity right, so they attract. I stuck the centre pads from the rings used to reinforce the holes in paper used with ring binders to their North poles, so I don’t create a levitator. FloorTwo is contoured to hold the soldering iron stand. That is secured somewhat by the magnets, but I haven’t secured it so much that it can’t be removed to be placed wherever needed on the workbench while soldering. Keith Anderson, Kingston, Tas. ($60) Simple emergency light uses tool batteries I have many 18V Lithium-ion cordless drill batteries and wanted some LED lights capable of being powered by the batteries to provide lighting in case of a blackout. The battery voltage ranges from below 15V (3V x 5) when flat to about 21V (4.2V x 5) when fully charged, so the lights must be capable of working across this range. LED work lights are widely available for both 12V and 24V systems. I purchased two “27W” nine-LED work lights from AliExpress with an operating voltage specified as 9-32V DC. Testing on a bench power supply showed almost constant power from 12V to 30V (the limit of my power supply). One light drew 11.5W and the other 10.5W. To complete these work lights requires a battery, battery connector, power switch and light. My batteries are from the Ozito 88 Silicon Chip PXC series, sold at Bunnings. AliExpress sells battery connectors for various battery brands, but the Ozito type is hard to find. A Makita-style terminal will fit the Ozito batteries if the centre section is cut out and the remaining parts are bolted together with the terminals 24mm apart. In a pinch, male spade crimp connectors can be inserted into the battery directly – watch the polarity! Another option is to modify an Ozito 18V USB Power Station (Bunnings Cat 6290517) by removing the top cover and soldering wires to the battery connections on the circuit board inside. You can bring the wires out through a hole drilled in the top cover. If desired, the mounting holes in the top cover can be drilled through, and longer replacement screws can be used to attach the Power Station to a Jiffy box. Consideration must be given to Australia's electronics magazine prevent the over-discharge of Li-ion batteries as this can cause internal degradation and, ultimately, failure. Luckily, the Ozito batteries have a built-in battery management system (BMS) which includes a low-voltage cutout, so I did not need to add an external cutout. Winston Campbell, Wagga Wagga, NSW ($50). Editor’s note: Four types of Ozito PXC-compatible LED lamps are available from Bunnings, ranging from a 3W LED handheld torch (Cat 6210747, $25) to dual 2000lm work lights on a tripod (Cat 0136010, $119). I have their 18V LED work light (Cat 0136011, $55) and am happy with it; it has adjustable brightness, a sturdy stand, and folds up for storage. Still, Winston’s solution will be considerably cheaper and brighter if you’re willing to do a little work. siliconchip.com.au Multiprocessor stack and terminal switch using Pi Picos Four Raspberry Pi Picos can be configured as an eight-core multiprocessor with vastly expanded I/O capability. Vertically stacking the Picos retains the small footprint. Insulating spacers separate Picos in the stack via the 2mm holes provided. Cable ties allow for quick disassembly. The lowest Pico in the stack is named “home” and operates as a terminal switch. Installing pin headers to plug into an existing motherboard is a good option, but neat construction becomes challenging. The three Picos above “home” in the stack are named “larry”, “moe” and “curly”. The pins of these three Picos are uncommitted, except for the three pins in the top left corner, which are used to communicate with “home”. This configuration has one switching node and three terminal nodes because the Pico provides TX/RX/GND pins for each UART in three locations. The one-page MMBasic program running on “home” lets the user switch serial communications from one of the three terminal nodes to the “home” console. Although the “home” console is active for only one terminal node at a time, the terminal nodes continue to run for as long as they receive power. Only three connections are essential for each terminal node: GND, RX and TX. The RX and TX connections cross over between the switching and terminal nodes. As the “home” connections are more numerous, if pin headers are fitted, these connections can be soldered to the outside of the castellated pad. This is a practical construction method; however, your soldering skills may be tested! Try to avoid affecting the tiny surface mount components on the upper side of the Pico and melting the plastic spacers of the pin headers. There are many potential solutions for powering the four devices in the stack. Initial testing can be performed by supplying power through the USB connectors. A four-port USB hub (or a handful of USB power supplies) and multiple USB cables are convenient for powering the Pico stack. If the Picos are clocked at 48MHz, they draw around 10mA each. Depending on the type of power supply used, that might not be enough to keep the brick switched on, causing periodic reboots. All the Picos in the stack are configured with their console on COM1 (GP0/GP1/GND). The console of the “home” Pico can be connected to Geoff Graham’s ASCII Video Terminal (July 2014; siliconchip.au/Article/7925) or a computer with terminal emulation software like TeraTerm or PuTTY. After building the hardware, begin the software installation by copying MMBasic to all four Picos. Work down the stack, finishing with “home”. Next, an MMBasic program needs to be saved to flash memory for each Pico in the stack. The easiest method to transfer the MMBasic program to “home” is to temporarily configure an SD card interface. If you have a socketed VGA PicoMite (July 2022; siliconchip.au/Article/15382) & built the stack with pin headers, you can use the PicoMite’s SD card interface. Copy the terminal switching program from the SD card (“LOAD tsw10. bas”) and save it to flash memory (“FLASH SAVE 1”). Once you are confident everything is working correctly, remove the SD card connection and switch the console to the ASCII Video Terminal using “OPTION SERIAL CONSOLE GP1, GP0”. Verify the Terminal’s operation. The short program running on each terminal node can be entered by hand to avoid having to configure an SD card interface. The program sets an MMBasic prompt to identify the respective Pico. Connect to each terminal node Pico in turn, and create a new program like the following: Sub mm.prompt print “larry> ”; End Sub Change the prompt depending on the Pico and save it to flash memory. Once the prompt works, switch the MMBasic console to the “home” Pico, again using “OPTION SERIAL CONSOLE GP1, GP0”. Finally, the acid test. Power up all four Pico’s in the stack and the Terminal. You should be greeted with an MMBasic prompt, switchable between the terminal Picos using the F8 key. Example software is available from: siliconchip.com.au/Shop/6/170 Mike Sunners, Mount Barker, SA ($100). SERVICEMAN’S LOG You win some, you lose some Dave Thompson There’s often a perception about servicing stories that our repairs are always successful, no matter how bleak things might look. Like the hero in an action movie, even though everything is stacked against us, we always emerge victorious. Still, even James Bond doesn’t win them all. Let’s face it; the reality is that most jobs we do are mundane and barely worth even mentioning. It is mostly bread and butter work that we all get in on a daily basis and are usually tasks we can do in our sleep (and sometimes almost do!). However, these stories typically never get told, because who but the keenest of knowledge-hounds wants to hear or read about that sort of thing? The stories that do get relayed are those that have had particular challenges to overcome or some clever bit of diagnosis required to make it work. It is these tales that we brag about (and often rightly so). That’s essentially what this column is all about; finding solutions to curly problems (we’ve all had them) that might be a little out of the box. We relate these situations in riveting stories, possibly adding to the great knowledge pool that has been organically growing for many years. The idea of apprenticeships and other such roles is similar; to pass knowledge from one generation to another, making it easier for the new guys coming through by tapping into an already-proven knowledge and skill base. This training may or may not cover the latest technology; those teaching might not be up to speed with the most modern of devices and tech in the workplace. That was sometimes the case at the airline I worked at; historical theory and practice, often going back to the postwar decades, was no problem. Still, keeping up with the latest trends was not necessarily a priority, especially for older engineers. In all fairness, they’d likely never need any of that in the roles they were in anyway. It happens; as many of us get older, we settle into our comfort zones and routines and simply cruise through with what we know. Constant up-skilling is often too time-­ consuming to be practical, especially if we are also expected to work away at our regular jobs at the same time. Items Covered This Month • • • • Learning when to pull the plug Detecting micro-bats Fixing an anti-barking dog collar Repairing a series of solar party lights 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 90 Silicon Chip All that aside, even if we know and are comfortable with what we are doing, sometimes things don’t work out. Knowing when to pull the plug on a job is as important as knowing when to keep plodding forwards. I hate being beaten by anything, but it happens, and we all have to deal with it in our own way. An essential part of a serviceman’s skill set is being able to ‘triage’ or assess any potential job and know whether to take it on or not. Often, we hedge our bets and go for it, only to have it come around and bite us. Such is life, and over the years, I’ve had some jobs I spent way too much time on for absolutely no reward. Monetary compensation is one thing, but the satisfaction of a job well done often outstrips that for me. Perhaps that’s why I keep doing it! Built like a brick outhouse One job that came in recently was a Yamaha home theatre amplifier. The owner is someone I’ve dealt with and done computer repairs for over many years. When he saw an amplifier on my bench last time he was in, he asked whether I could have a look at his. Apparently, it would not switch on any longer. He suspected a fuse or similar, and I agreed that I’d assess it and see what, if anything, I could do. I was expecting a normal home-theatre-type amp, maybe 50-100W per channel, the sort of thing most people have in their lounge rooms. When my client backed up the drive and opened his SUV’s back door, and I went to lift it out, he warned that it was “quite heavy”. When I saw it, I understood why; it was an absolute monster! The first thing I noticed was the vast array of RCA sockets, speaker posts and other connectors covering almost the entire back panel. The second was that I almost put my back out when I tried to lift it clear! I’ve worked with some big amps in the past, primarily sound-reinforcement PA amps with huge transformers and heatsinks, but this was the biggest, baddest domestic amp I’d ever seen. The specs on the back panel claim 500W per channel into 8W with all the Dolby and DSP that anyone could ever want. The front panel boasts the requisite huge volume knob, digital display and soft-touch buttons everywhere. The guy saw me eyeballing the amp and admitted he’d probably ‘overpurchased’ a little, but my thinking is that he likes it, and that’s all that matters. I lugged it to my workbench and plugged it into the power. Sure enough, the symptoms were what he’d reported – it Australia's electronics magazine siliconchip.com.au just wouldn’t turn on. There were also no lights anywhere and the display was dark. The mains socket on the back panel, likely used to power up a turntable or other connected device, also had nothing coming out of it. Having completed the preliminary tests, I advised him to leave it with me. I told him I’d crack the case and check any onboard fuses that might be present. If we were lucky, it could be as simple as replacing one that had blown (although it rarely is that simple). I mentioned it could also be a dud power on/off microswitch, which would prevent everything else from working, but it felt like it was toggling OK to me. I also warned him that unless I could find circuits for it, I’d just be running around in the dark looking for anything untoward. He was fine with that, as the only repair agent in the country was ‘up north’, and shipping this thing all the way up there would be a major headache. He wanted to have at least a rough idea of what could be wrong with it, as that information could help him decide how to proceed. Apparently, the agents had (very helpfully!) told him that this particular model was no longer sold, the parts were not readily available, and he’d likely end up having to buy a new one. At around $4000 for the replacement model, that’s a whole lot to lose. So, no pressure then. far, it would never work. In this case, I measured 235V AC at the socket and into the transformer’s primary. A good start! The problem was, I couldn’t pick up anything at the secondaries. Power going in, nothing coming out can only point to one thing, which was bad news. Especially because this transformer had four separate secondaries that I could see, and none were live. Of course, I couldn’t find any numbers on the transformer, and I couldn’t find any circuits on the web for this unit. Likely it was a proprietary transformer, and while they might have used the same components in other large amps (it turns out there was quite a range of them), I couldn’t find anything on the usual auction and sales sites that was going to replace this one. There were no inline fuses or anything of that nature that I could see – it was all very much a classic meat and three-veg setup. So, sadly, that is where my involvement ended. I put the covers back on and told my client that if he wanted it repaired, he’d have to send it to the repair agents and take his chances that they could be bothered to locate a transformer for it. I’m sure the parts are out there; like any closed shop system, the repair agents will likely have access to all of them, and the circuits. If they’ve been doing this for a while, they might even have a suitable transformer under the bench in a dead unit. Because I don’t have access to any of those parts or information, that was pretty much it, as far as I was concerned. Sourcing parts is getting harder This happens all the time for us servicemen, even with computer repairs, especially with the likes of Dell or older HP machines that used proprietary hardware. Getting any components for them was always an uphill battle. I did manage to source a lot of stuff from websites like AliExpress and eBay, where people buy up old machines, strip them down, vet the parts and then on-sell them, but Dave and ‘Goliath’ I started the usual way, by removing the covers. It was beautifully made; on many similar devices, the covers are often like guillotines, ready to slice me open if I mishandle them slightly. Not so this one – all the metal edges were rolled and smooth. The interior was the same, with the cabling all beautifully routed via clips and channels, and the circuit boards packed in tightly. I can certainly see why it cost so much. The layout is pretty much the same as any big amplifier – power supply and transformer off to the right, preamp boards as close to the input sockets at the rear as possible and the huge heatsink and power amp board spanning the whole case near the front. The first step was to track power through from the mains input socket to the transformer. If it wasn’t getting that siliconchip.com.au Australia's electronics magazine May 2023  91 it’s not an ideal solution. I’ve bought many a rare motherboard from vendors like that, only to have it arrive and discover it is faulty or doesn’t work at all. These days, I assess and don’t even bother offering that option, mainly because of the blowback that invariably comes from going down that repair road. The last part I ordered from China took over 15 weeks to arrive, with the client calling every other day to see if their machine was finished. For most of us, this hassle just isn’t worth the grief, so we pull the plug before it gets to that point. Recently, I’ve had several e-scooters, dashcams, musical keyboards and dead laptops that I’ve passed on repairing for this very reason. Beastly laptop update One laptop I did take on warrants a mention just because of the fiasco it turned into. If this story sounds familiar, it’s because I initially described it in the July 2021 issue, but more has happened since then, so here’s the whole sorry saga. This machine was a gaming laptop purchased in the USA. It was a massive thing made by Dell’s skunkworks department, with a 19-inch screen, and to this day still the biggest laptop I’ve ever seen. It was not the sort of machine you’d want to carry around because it weighed a ton, and the size and weight meant that the carry bag and power supply to support it were equally massive. It was designed more as a gaming desktop replacement machine and, as such, boasted a fast Intel mobile i7 CPU, 32 gigs of RAM, two hard drives in RAID0 configuration and dual removable graphics cards – an unusual feature in a laptop. This machine had given a good few years of service after the guy brought it home, but now it had given up. It wouldn’t boot, no lights. The power supply checked out – one of the traps to look for when people bring a machine in that won’t boot is that the power supply has failed, the battery has gone flat and, of course, it won’t start up. Plenty of repair people tell a customer the machine is dead when all it has is a flat battery. Sometimes I can simply replace the power supply and off it goes. Sadly, in this case, the PSU was OK. I also had a similar (but smaller) Dell supply that would do the job, though due to how those machines worked, even if it powered it up, the laptop would likely report I had the wrong supply connected every time anyone tried to start it. That’s a real annoyance for people who need to replace their dead original supply with a third-party one! 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. 92 Silicon Chip Yet, it still could be a battery fault causing the problem, so the next step was to crack the case, extract the battery and measure that. It seemed to be charged; this wasn’t looking good. After removing the hard drives and RAM and reseating the CPU, it still wouldn’t power up, so I could only advise the client that the motherboard was the likely suspect. Most people would have called it there and then, but as this guy had so much invested, he wanted to see if we could replace the board. And we could; while Dell was of no use at all parts-wise, I could get a refurbished board from China. It was expensive, but delivery was just a few weeks back then, so I ordered it and fitted it when it arrived. The machine booted and ran quite happily – for about four months, when it came in again, this time with a new problem: no video output. It seemed the video cards, which had been swapped into the new motherboard from the ‘old’ setup, had failed. I tried swapping them from one side to the other to no avail. The onboard video worked, which was weird, but it wasn’t accelerated and was no good for gaming. So, I ordered two refurbished graphics cards from China at a considerable cost ($400 each!). When I installed them and powered up the machine for the first time, actual smoke came out of one of the graphics cards, and there was still no video output. Great. I removed the one that let out the smoke, and the machine started. Both the client and I were getting jaded by now. Fortunately, the games he played worked well with just one card, and that’s the way it stayed for another six months. Then it was back in the workshop – not booting. Once again, it looked like a motherboard issue. By now, both my patience and the client’s resolve were wearing thin. Aside from the warranty side of things, which, to be fair, he was very philosophical about, I was done with this machine. It had cost me a lot of time and money; I hadn’t charged him what I really should have to make it worth my while, so it was time to pull the plug. I saved all his game data, broke the machine down into components, and he sold off what he could while sourcing a new replacement. Sometimes things don’t work out. Success stories are great, but servicemen and women must accept that sometimes, there’s nothing more you can realistically do. Knowing when to pull the pin is a very valuable skill to have. “Micro-bat” detector repair A. E., of Newcomb, Vic went a bit batty trying to determine whether his ultrasonic detector repair was successful. He used one key technique to determine that it was... It’s hard to repair an electronic device of an unusual type, perhaps almost unique, when it fails and there’s little or no documentation. This was my predicament when a biologist showed me a small battery-operated device about the size of a pocket radio. It was a detector that had been acquired to find very tiny bats in Tasmanian forests. Zoologists call them “micro-bats”. Though smaller than a thumb, they will hunt moths larger than themselves, clinging on to them as they try to fly away! You can find more information on them at siliconchip.au/link/abjt From the biologist’s account, the device had been made an ocean away (in North America) some time ago and was unencumbered by technical specs or a circuit diagram. Australia's electronics magazine siliconchip.com.au A selection of our best selling soldering irons and accessories at great Jaycar value! 25W Soldering Iron TS1465 $16.95 Build, repair or service with our Soldering Solutions. We stock a GREAT RANGE of gas and electric soldering irons, solder, service aids and workbench essentials. 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Jaycar reserves the right to change prices if and when required. Fixing an anti-barking dog collar At least the principle of its operation was known – a microphone that could register ultrasounds up to perhaps 100kHz was followed by an amplifier, then a frequency divider that would shift the ultrasounds down into noises that we could hear. The battery checked out OK, and there was even a reasonable current drain of over 10mA when the detector was turned on. But the only sound emitted was a very faint hiss. Where was I to start? Tracing the input signal showed that the small electret microphone fed the signal into a two-transistor preamplifier and then into a comparator that was followed by either a mixer or frequency divider. Checking the collector voltage of the first transistor, I found that it was less than half a volt, well and truly in saturation. I wondered whether the detector’s builder had chosen the wrong biasing resistances. Had the wrong transistor been inserted, or had some component values drifted over time? A simple change to the biasing turned out to be all that was needed. When a change to the bias of the input stage raised the collector to a few volts, the detector started to show some signs of life; there was a hissing noise from the little internal speaker and even some crackling sounds. So then the question was, would the detector actually betray the presence of 40-50kHz squeaks? I can whistle a bit, but not anywhere near that frequency. The answer wasn’t long in coming, though. A co-worker in the lab entered a long corridor nearby and pulled a ring of keys from his pocket. The bunch of keys, although more than twenty metres away, and around a corner, caused a riotous burst of sharp sounds from the detector. The keys only made a faint jangling sound, but the detector made their ultrasound components loud enough to be uncomfortable to human ears! If you ever need a broadband ultrasound source, there’s the key. The happy owner of the device subsequently took the detector out into the Tasmanian bush and reported later that he was able to find some of the elusive little bats. 94 Silicon Chip D. S., of Maryborough, Qld had a repair job that turned out to be very obvious and very easy to fix, which made the customer happy and put a smile on his bank manager’s face... Sometimes, but not often, a job comes in that turns out to be a simple fix. Also sometimes, we miss the obvious and look for a much more challenging solution. The job was an anti-barking collar for a dog. This collar detects the dog barking through a small microphone adjacent to the dog’s throat and then does a couple of things to deter or stop the barking. Firstly, the collar vibrates when it detects barking. If this vibration does not deter the dog, it vibrates again a lot stronger after a 10-second delay. Continued barking will force the third stage, which is an electric shock. The shock is delivered through two metal prongs that press against the dog’s throat. Before I am told how cruel this is and that there are many other less cruel deterrents, this collar is not mine! As the owner of two large dogs, I understand the folks that would not want to put their dogs through this, including myself, but many councils now have very strict laws regarding barking dogs, especially nuisance barking, where a dog barks for long periods. Continued nuisance barking can bring harsh penalties to owners and, in extreme cases, result in the dog being put to sleep. So, a small shock from an anti-barking collar could be preferable to the alternative. This collar is powered by a small 3.7V lithium-ion rechargeable battery inside the collar that can be recharged through a small USB-C socket on the collar’s body. The USB socket is protected by a tight-fitting silicone cover that seals dirt and moisture out when fitted. The battery lasts for several days unless the wearer is barking a lot. The collar has various options, such as vibration duration, shock strength and sensitivity, controlled via two touch-sensitive dimples on the front of the collar body, which also switch it on and off. The option and settings are shown on a tiny two-digit display. When I opened the collar, I found the battery to be fully charged but the collar was lifeless. It is made up of two PCBs. The main PCB contained all the power and charging circuitry along with the boost circuitry and vibrator motor, while the other was the controller. Shock Probe MIC Shock Probe The internals of the dog collar and where the shock probes are located. Australia's electronics magazine siliconchip.com.au ONLY 289 $ QM1493 Specialty meters combined with multimeter functions. 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Jaycar reserves the right to change prices if and when required. I began by tracing the battery voltage across the main board where, after a degree of filtering, it left the main PCB through a ribbon cable over to the control PCB, which also contained the microcontroller. However, there was no power to the micro. In fact, no power was reaching the control PCB at all. It did show on the PCB connector for the ribbon cable on the main PCB, so I checked the control end of the ribbon cable for power. I found a lot of corrosion on both the ribbon cable and the PCB connector on the control PCB. So out came the alcohol, cotton buds and a small, stiff brush. With such small components, it took me about 20 minutes to remove the corrosion from the cable and its connector. I also removed the control board from the top shell to check for any damage below the connector, and the main PCB to check for the same. The main PCB was a bit tricky to remove due to the seals around the openings where the shock prongs went through the case. In the end, everything checked out fine, and I refitted the ribbon cable and gave everything a quick squirt of electrical sealant. I did notice a failure of the case seal where the two halves of the case joined, so after cleaning it, I resealed the case with a little neutral-cure silicone sealant. Touching the power dimple brought forth a pleasing beep, and the display showed the remaining battery time. To test the unit, I barked at it (much to the surprise of my dogs), and it did indeed vibrate. A second bark gave a much stronger vibration. At this point, my dogs decided that I was barking at them, and they barked back at me. This meant the collar did as programmed to do, giving out a shock. As I was holding the collar (and not intending to bark for a third time), I received the shock! The shock was nowhere near as powerful as the one you might receive from an electric fence, but it is still a shock, and is worse when you are not expecting it, as I wasn’t. 96 Silicon Chip The resulting “yowch “ from me and the bang of the collar hitting the surface of my bench was enough for my dogs to turn tail and make for the house. I gingerly picked the collar up and turned it off. I have to admit, when I told the customer the story, we both laughed, and he was more than happy with the repair cost (which was very little, as I hadn’t done a great deal). I can still hear my wife laughing when I told her what happened, and I believe both dogs received an extra treat that night. Lights out for the solar party A. R., of Greenbank, Qld decided to take on one of those repairs that seemed like it would be something simple, but it actually turned out to be a rather confusing manufacturing fault... My son called to ask if I could fix his solar panels. I hesitated, knowing they are not easily repairable. I asked him what kind of solar panel; he explained that his solar-­ powered party lights weren’t working, so he presumed the solar panel was faulty. I offered to take a look. The solar party lights consist of a control box about 140 × 100mm with a solar panel embedded in one face. A 200mm-long cable emerges from one side with a sealed plug/socket on the end. A string of light fittings is connected to the plug. Each ‘light bulb’ consists of a socket with an Edison screw bulb, and the whole assembly is well sealed and quite well made. The ‘bulb’ is a small glass envelope with an LED bar inside. I removed a bulb and noted 24V printed on the side. That was not quite what I expected, so I carefully applied a DC voltage to the lamp, assuming positive went to the tip, and it lit up nicely with a reasonable power draw, confirming it was indeed a 24V lamp. The control unit has two sealed switches on the rear, on/off and mode, and a small dark device shaped like an LED. I unplugged the light cable assembly from the unit, removed the eight screws holding on the rear panel, and opened the case. This revealed a control board and a sizeable 3.6V lithium cell. The solar cell and battery cell connecting wires were soldered to the board. I found the battery voltage to be about 3.2V. My next step was determining if the solar panel was charging the battery. I took it out into the sun and measured the battery voltage, which was slowly increasing. So the solar panel was OK, and so was the charging circuit on the card. With no lights plugged in, I pressed the on/off switch to turn the unit on. There are two small green SMD LEDs marked W3 and W4 at the top left of the board. These started flashing alternately. Pressing the mode switch changed the flashing pattern on the LEDs, which were obviously mirroring what was supposed to be happening with the light string. I tested the continuity of the cable to the external connector. This and the socket checked OK. I applied 24V to the plug on the light string, and the lamps lit up. So what was happening? I pressed mode until I got two steady green LEDs, then measured the voltage across the output. This gave 3V DC, which was not what I expected, so maybe the output driver stage was faulty. I guessed that the surface-mount transistors marked Q1, Q2, Q4 and Q5 were probably part of the output stage and, thus, the obvious suspects. I measured them with my multimeter set on ohms and, Australia's electronics magazine siliconchip.com.au Ventilation Fans We stock a wide range of DC and AC powered enclosure fans to keep your projects cool. A GREAT RANGE AT GREAT PRICES. 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Jaycar reserves the right to change prices if and when required. Left: the internals of the control unit for the LED ‘party light’ system. Note the object with the white ring around it; its purpose is unclear. Right: a section of the traced circuit for the control unit. after some trial and error, found two NPN and two PNP transistors with standard SMD footprints, all apparently OK. I was starting to get suspicious because something obviously wasn’t right. There had to be some clever device converting the 3.6V from the battery to the 24V required by the lamps, and I assumed this was the smaller IC’s function. So it was time to trace out the circuit. I had to remove the large on/off switch to see where the traces under it went. The board has two ICs with all markings completely removed and numerous passive components. There are also several components not fitted and, curiously, an SMD LED located under the switch with one end not soldered to anything, and the other end soldered to one pad of a component marked C3. One of the components not fitted was marked L1, an inductor I would have expected somewhere in the circuit of a DC/DC converter. In the bottom right-hand corner of the PCB were two manufacturing marks, one for 3V and one for 24V, and the 24V mark was clearly selected. So the control board was supposed to be set up for 24V from the factory. The larger controller IC is powered via the on/off switch. The output from the controller drives a bridge circuit, including transistors Q1, Q2, Q4 and Q5. The supply for this driver is from the battery via R12, a 9.1W SMD resistor. This arrangement clearly cannot ever deliver 24V. The smaller IC marked U1 appears to control the charge current to the lithium-ion cell to stop overcharge and overdischarge. With power on, I measured the power supply to the controller and the output driver at 3.2V, the battery voltage. It was clear to me now that this device was manufactured incorrectly. Despite being marked as 24V, it was actually set up for 3V and could never have worked from the factory, obviously never having been tested before shipping. I quizzed my son further. He confessed he had bought the lights from an internet marketplace, and the seller assured him they worked; they just didn’t need them any more! A likely story... I assumed the missing components must provide the DC/DC converter function. Could I get this working? The adjacent circuit fragment shows the missing components, with L1, C3, Q3 and D2 forming a DC/DC boost converter. The controller feeds a square wave to switch Q3 via R5/ C4. When Q3 switches on, current flows through L1, storing energy in its magnetic field. When Q3 switches off, 98 Silicon Chip the energy stored in the magnetic field causes the current to continue to flow from +3.6V via D2 to C3, increasing the voltage across C3 above +3.6V. The duty cycle sets the voltage across C3. I had no values to go on for any of the components. I fitted an NPN SMD transistor from my recycled components box for Q3, and a through-hole schottky diode in place of D2. I hunted around and found some inductors salvaged from an old TV PCB, fitting a 1μF capacitor for C3. I also removed R12, disconnecting the driver stage supply from the battery. It should now be driven by the voltage across C3. At the same time, I removed drive resistor R14 to the SMD LEDs, which at 2.7kW might not be suitable for 24V output, and replaced it with a 33kW resistor, as well as changing two of the 2.7kW resistors in the driver stage to 15kW. I crossed my fingers and powered up. With my oscilloscope, I could see that Q3 was now fed with a square wave from pin 5 of the controller, and the voltage across C3 was about 5V. I was on the right track. After many hours of trial and error, I found that a 1mH inductor for L1 and a 10μF capacitor for C3 worked quite well. After starting at 10kW for R5 and 100kW for R8, I reduced R5 to 1.5kW. A value of 100nF for C4 squares up the switching waveform of Q3. The result is about 22V across C3. Not quite 24V, but to get any more would need a wider switching pulse width from pin 5 of the controller IC, and there was no control over this that I could see. The W3 and W4 SMD LEDs are pretty bright, which is interesting given that they have less than 0.7mA drive current and are not even visible outside the box. The main LED string now lights up quite brightly and operates as expected. This was not quite the journey I had expected at the start! One mystery remains – the purpose of the sensor with the white collar. It is not to stop the lights from operating during the day; another part of the circuit senses the output from the solar panels and feeds an input to the controller to achieve this. The output of this sensor goes to the controller and is always high. Exposing it to light or completely shading it makes no difference, neither does any movement in front of it. So that is a mystery for another day. SC Australia's electronics magazine siliconchip.com.au Keep your electronics safe with our HUGE RANGE of Low Voltage Circuit Protection SAME GREAT RANGE AT SAME GREAT PRICE. 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Jaycar reserves the right to change prices if and when required. JUST 2895 $ Vintage Radio Astor’s first transistor radio – The APN By Ian Batty While Astor was beaten to the transistor radio market in Australia by AWA, first is not always best. The circuit used in Astor’s APN became the template for many Australian transistor sets that followed it. With a smaller case and superior electronic design, the APN is a notable ‘first outing’ for the famous Astor brand. As with other Astor sets I’ve reviewed, mass production and popularity don’t necessarily mean cheap and sloppy design. This radio’s performance is comparable to other contemporary sets, while its visual design is unmistakable. While I can’t claim the misguided genius of Viktor Frankenstein, my radio (see Photo 5) is an assemblage of parts. It’s an all-transistor APN chassis in a case taken from an all-valve BRQ. 100 Silicon Chip Luckily, Astor didn’t make too many changes to the BRQ’s case when they reused it for the APN, so unless you know what you are looking at, you probably won’t notice the substitution. The APN is one of a family of radios released in the changeover from valves to transistors. These continued the valve sets’ visual designs but popped in transistor-based circuitry. A good number used identical cases. Geoff Trengove and Jim Greig published part one of a two-part series in the January 2023 issue of Radio Waves that included a complete survey of such sets. Australia's electronics magazine The only difference between the case for the APN and the BRQ is that the former lacked the hole for the On/ Off/Battery/Mains switch on the right side, and the power cord cutout in the rear flap (because the BRQ was mains-­ powered but the APN is a battery set). The APN also bears the label “TRANSISTOR” in place of the BRQ’s “SPORTSTER” beneath the speaker cutout. There’s also a label above the volume control on the BRQ labelled OFF ON VOLUME, which is missing from the APN since it has no such switch. siliconchip.com.au Internally, the APN uses a separate sub-chassis for the audio and RF/IF sections – see Photo 1. The RF/IF section is on the right, where the BRQ signal circuitry was located (Photo 2). While three transistors occupy a lot less space than four valves, the APN adds a third IF can, so the space savings are not huge. The three-­transistor audio section sits in a previously-­ unused space at the top of the case (Photo 3). The APN replaces the BRQ’s mains power supply (with its transformer and large filter capacitors) with a parallel pair of 276P 9V batteries. Aside from the transistors, all components are of similar size to those in the BRQ. Circuit description You might think that the APN circuit (Fig.1) looks pretty much like any other six-transistor set. In fact, the APN set the template for Australian transistor sets, with a self-excited converter, two IF stages and a diode demodulator with AGC to the first IF stage. The audio section comprises an audio driver and transformer-coupled Class-B output. The APN’s performance rivals that of the look-alike BRQ four-valve set. Astor’s APN showed AWA’s 897P to be a mediocre design, as the 897P needed seven transistors to give only marginally better performance. Astor drawings simply number components in order. Items #1 to #22 are resistors, #26 to #45 are capacitors, #50 to #56 are inductors, #57 is the battery and #58 is the speaker. I’ve preserved this scheme to prevent confusion; however, I’ve numbered the transistors Photo 1: the interior of the Astor APN is divided into two separate chassis for the audio & RF/IF sections. The audio section is primarily above and around the Rola speaker, while the RF/IF section is located on the right, as shown by the large IF cans mounted horizontally. Photo 2: the APN chassis metalwork is based on (and nearly identical to) the allvalve Astor BRQ, with the BRQ shown here for comparison. Photo 3: a closer look at the audio section of the APN. Astor decided to utilise the empty space below the ferrite rod antenna to house the components. siliconchip.com.au Australia's electronics magazine May 2023  101 Q1~Q6 and the demodulator D1, as Astor omitted such labels. The local oscillator uses collector-­ emitter feedback, operating the oscillator transistor in a grounded-base configuration, guaranteeing reliable oscillation across the broadcast band. As the base is not in the oscillator circuit, local oscillator radiation via the antenna circuit is minimised. Q1’s forward bias seems too low at only around 70-100mV, but that’s because Q1 runs in Class-B, giving it the nonlinear operation vital to the mixing function. Australian manufacturers generally used tuning gangs with identical sections, necessitating a padder capacitor to get the LO to track the antenna circuit. In the APN, this is #30, a fixed 310pF capacitor. The converter feeds the tuned, tapped primary of the first IF transformer, #52. Tapping the primary allows the transformer to exhibit a high Q factor without its tuned circuit being damped by Q1’s relatively low output impedance, typically under 50kW. The first IF amplifier (Q2) uses simple capacitive neutralisation thanks to 6pF capacitor #35. This eliminates the feedback effects of its inherent collector-­ base capacitance (see the panel for more details). The voltage drop across 330W emitter resistor #5 indicates a standing collector current of around 0.6mA (600μA). This will fall as the AGC circuit acts to reduce the first IF’s gain on strong stations. Q2’s bias circuit uses a high-value resistor from the supply (#12, 100kW) so that the AGC voltage (supplied via #11, 2.2kW) can effectively control Q2’s collector current and thus, the stage gain. The second IF stage (Q3) uses fixed bias, with a standing collector current of just over 1.3mA. This stage is not neutralised, perhaps due to the demodulator loading the third IF transformer (#54), giving a lower gain. Both IF stages have their bypassing (base and IF transformer) tied back to their emitters. This single-point method gives highly effective bypassing and reduces the component count by eliminating the usual emitter bypass capacitor. Diode demodulator D1 feeds demodulated audio to 5kW volume control potentiometer #13 and, via filter resistor #11, to the AGC line. The AGC line is filtered by 15μF capacitor #33, removing any audio signal and producing a simple DC control voltage. The audio signal feeds to audio driver transistor Q4 via 2μF coupling Transistor Neutralisation Some textbooks describe neutralisation in terms of feedback. Capacitor #35 applies positive feedback from the collector’s tuned circuit to the base. I verified this by increasing #35 to 10pF. That doubled the sensitivity compared to the recommended circuit, confirming that the neutralising capacitor applies positive feedback. It was tempting to ‘hot up’ the APN to equal the 897P’s superior performance this way, but I resisted. Consider the effect of the transistor’s collector-base capacitance; since the collector signal is an amplified, inverted version of the base signal, collector-­ base feedback is negative. The point of the positive feedback from capacitor #35 is to cancel this out. So you can think of neutralisation as adding a balancing circuit that nulls out the effects of collector-base feedback. I addressed the matter of anode-grid feedback in valves in my article on the Grebe Synchrophase radio in the February 2018 issue (siliconchip.au/ Article/10977). The same principles apply to transistor circuits, except that some designs account for transistor feedback’s complex nature. While a valve feedback’s phase angle is ideally 180º, transistor feedback deviates from this as the internal feedback contains resistive and capacitive elements. A simple capacitive circuit cannot totally counteract such a complex feedback effect. Full correction demands a resistive-capacitive neutralising circuit, properly known as ‘unilateralisation’. With unilateralisation, the signal in the amplifying circuit flows only from the input to the output and never in the reverse direction. Regency’s TR-1 (described in the April 2013 issue; siliconchip.au/Article/3761) uses such a design. 102 Silicon Chip Australia's electronics magazine capacitor #40. Q4 uses combination bias, with a voltage divider formed from resistors #14 and #16 and 1.8kW emitter resistor #17. There is a feedback path from the speaker connection via resistor-capacitor combination #18/#43 and series resistor #15. Transistor Q4 feeds driver and phase-splitter transformer #55, with top-cut provided by 4.7nF capacitor #41. The output stage Q5/Q6 operates in Class-B, with around 150mV of bias provided by resistive divider #20/#21 and thermally-compensated by NTC thermistor #19. Q5 and Q6 share emitter resistor #22 and drive output transformer #56, which in turn drives speaker #58. 47nF capacitor #44 applies top-cut to the output transformer. Class-B operation provides better efficiency than Class-A. Of the transistor sets I’ve tested for Silicon Chip that use Class-A, only one manages even 30% efficiency (the GE P807). Terman (siliconchip.au/link/abje) quotes Class-A’s maximum theoretical efficiency as 50%, with typical values of 20-35% (p391). The same source puts Class-B’s maximum theoretical efficiency at 78%, with common values of 50-60% (p393). The APN’s Class-B output stage gives a maximum power efficiency of around 46% for full audio output, which may not seem like much of an improvement over a good Class-A stage. But the APN’s full output comes with a battery drain of around 63mA on peaks. A 250mW Class-A output stage (with an efficiency of 30%) implies a standing power consumption of siliconchip.com.au Fig.1: a redrawn circuit diagram for the Astor APN. It uses just six transistors, one less than the competing AWA 897P. The Class-B output stage and dual 9V batteries gives a typical runtime of 200 hours. 750mW. This would give a constant battery current approaching 85mA, resulting in under 50 hours of operation from the pair of 276P batteries. Such an output stage would also demand extensive heatsinking and very precise biasing to prevent thermal runaway. As the set will rarely be run at full volume, the resulting average battery drain is much lower. Average listening levels allow a battery life exceeding 200 hours. Why two 9V batteries in parallel? I suspect two reasons – first, there was enough space, given that they removed the mains power supply used in the previous valve model. It would also be a marketing point, as the APN would give about 20 times the battery life of the previous BRQ valve set. Restoration The case cleaned up nicely, with the oddity that it appeared to be a case from the previous valve model (BRQ). The electronics were another story. It did work – just. Sensitivity was very poor, and it only seemed to tune from about 700~800kHz to around 1500kHz. The original metal can (TO-5 package) 2N484 converter transistor had been replaced by an all-glass OC44, and the original CK872 TO-5 audio driver was replaced by a TO-1 package 2N406. The audio output was distorted, so I first checked the output stage bias, which was too high. I tried removing the bias thermistor #19, but one lead siliconchip.com.au broke off from the resistive body. It was not repairable, so I replaced the bias circuit with a diode-connected transistor (see Fig.2). This has the advantage of giving the correct bias voltage that tracks correctly with temperature changes. The audio output was still low, going into clipping at under 100mW, and I wasn’t getting the expected 50mW output with 5mV at the audio input. The original CK878s showed very high leakage, so I replaced both with AC128s. I was able to disconnect the CK878s and leave them in place, preserving some visual originality. The volume control coupling capacitor (#40) measured low in capacitance, so I replaced it. I could then get 50mW of output with only 4mV input – about right for a three-­ transistor audio amplification stage. I then looked at the IF channel. I’ve previously warned against using paint/wax/other stuff for sealing adjustment slugs. This set had wax poured into the tops of the three IF cans, and the slugs were held tight. Maybe it was still in alignment, and I was just being fussy. Still, I thought the sensitivity was low, and I measured 2.5V DC at Q2’s emitter. It should have been about 0.15V; the problem was excessive collector leakage in Q2. So I replaced both Q2 and Q3 with OC45s. That fixed the excessive emitter voltages, which should have meant that the IF channel was working correctly again. The remaining low gain prompted me to try removing the sealing wax, so I removed and dismantled the three IF cans. Whatever the ‘foreign’ wax was, it had a much higher melting point than the manufacturer’s wax used to seal the coil windings. My heat gun had the wax on the windings dripping while the wax in the coil cores was only just softening. Rather than overheat the windings, I boiled a kettle, poured the water into a jug, and dunked the coil. This worked well enough with IF2 and IF3 Fig.2: I replaced the NTC thermistor with a diode-connected transistor (right) to provide the correct bias voltage with respect to temperature. Australia's electronics magazine May 2023  103 Photo 4: the LO coil is not easily adjustable on the APN (shown at far right), despite it having an adjustable slug. I had to spend quite a bit of time cleaning the wax out of the three other coils that someone else had added, so that they could be adjusted. to let me carefully extract the adjusting slugs with several ‘treatments’. I visited a machinery shop and came home with a ¼-inch, 26 thread-perinch (TPI) tap and die. The tap worked a treat. Held with no more than finger tension, I was able to clear the coils’ internal threads of wax gradually. Heating and swabbing the threads with cotton tips was not an option because I didn’t want to risk damaging the coil windings, and heating the wax would have allowed it to coat the internal thread evenly, worsening the problem. Curiously, although the tap seemed a correct fit to the coil thread, the adjusting slug would not drive into the matching die. There was definite interference, so I resorted to a fine wire brush to clean the slug threads. I managed to get IF2 and IF3 adjustable, but IF1 defied all my attempts. Luckily, the slug was well out of the coil, with the IF resonating at close to 520kHz. I first tried the easy way – bridging an extra capacitor across the primary of IF1 (in this case, 68pF). While this brought the resonance down to a bit below 460kHz, the resulting gain appeared low. That makes sense; Q = (1 ÷ R) × √L ÷ C, so a larger C, for the same L, reduces Q and thus, stage gain. My back-ofthe-envelope shows an expected Q reduction of about 15%, close to what I measured. So instead, I recovered a suitable slug from an old TV coil and popped it in. Luckily, the jammed slug was at the bottom of the IF, so the new one screwed easily into the top of the winding, and I could bring the IF down to 455kHz. I still didn’t have the gain I expected. 104 Silicon Chip The AGC filter capacitor (#33) was open-circuit, so I replaced it. The second IF amplification stage showed a low gain; the culprit was #37, the emitter bypass. It’s unusual to find a paper capacitor open-circuit, but I did, so be alert to that possibility. With the IF going, I looked at the converter stage. The ferrite rod’s leads must have broken at some point, as they were soldered to single-strand hook-up wire. I replaced the connections with flexible stranded wire and protected the joins with heatshrink tubing. After replacing the existing OC44 with one from my spares box, I found that the local oscillator would not work. I suspected the emitter coupling capacitor, #29. Remembering the faulty capacitor #37 in the IF strip, I replaced #29. The oscillator would still not work, and after much faffing about, I pulled my substitute OC44 and tested it. Its current gain (β or hfe) was only about 30. So I tested all the OC44s I had on hand and selected one with a β over 100. That got the set going at last. I was surprised to find that the oscillator transistor’s gain was so critical. OC44 specifications show a β range of 45~225, with 100 typical. Yes, my replacement had a β of only 30, but I’d have expected the designers to be pretty liberal and allow for low transistor gains. As with valve sets, it looks like the converter is the stage most sensitive to device performance. Perhaps they selected the OC44s for gain at the factory. With all that done, I was able to finish the alignment and complete my tests. The ferrite rod has a small Australia's electronics magazine auxiliary winding that can slide along its length to adjust the antenna circuit at 600kHz. While this works, I’d be careful not to ‘exercise’ it too much, as I expect the coil wiring to be delicate. One final niggle: the LO coil cannot be adjusted on this set. Yes, it does have an adjusting slug, but it’s obscured by a ferrite rod mounting bracket (see Photo 4). Transistor failures I’ve never had to replace every transistor in a radio. The APN is a reminder that transistor technology was advancing rapidly in the 1950s and 1960s, and didn’t really mature until silicon transistors became mainstream. You can still buy OC44/45s online, but you’ll likely get a better deal from the HRSA’s Transistor Bank (visit hrsa.org.au for more information). While it’s often possible to rejuvenate valves by over-running the filament/heater, I’ve not found any similar technique for transistors. That makes sense: valve emission depends on the chemical composition of the cathode coating, so it’s possible to ‘boil off’ contamination by overrunning. However, a semiconductor junction is intimately fused in manufacture, and degradation that increases leakage is unlikely to be remediable. There are two significant measures of leakage, ICBO and ICEO. ICBO is the current flow measured from collector to base (“CB”) with the emitter not connected (“O”), while ICEO is the current from collector to emitter (“CE”) with the base not connected. An ICBO of, say, 10μA might seem trivial, but it’s a base current, so the transistor’s current gain can magnify this to a collector current of 100μA or siliconchip.com.au considerably more. This would affect the ICEO. The leaky 2N484 in this set had an ICEO exceeding 10mA with a Vce of 10V. How good is it? For a first outing, it’s pretty good. The best comparison is AWA’s first transistor set, the 897P, which I previously reviewed (April 2015 issue; siliconchip.au/Article/8458). The 897 used seven transistors, with two interstage audio transformers for maximum gain in the four-transistor audio channel. This appears to be in compensation for the low overall gain of the RF/IF section. The 897’s audio gain is over ten times higher than that of the APN, so let’s keep that in mind. The APN’s RF sensitivity is 375μV/m at 600kHz and 200μV/m at 1400kHz. Both readings showed signal+noise to noise (S+N:N) ratios better than 20dB. Compared to the 897’s 250μV/m and 150μV/m, and discounting for the 897’s extra audio gain, the APN’s RF/ IF section has more gain overall. The APN’s actual performance is certainly on par with valve portables of the day. My favourite ‘distant’ station, Horsham’s ABC Western Victoria (3WV) on 594KHz, rocked in at full volume. The maximum audio output, at 10% total harmonic distortion (THD), is 260mW. At 50mW, THD is about 5%; at 10mW, it falls to 3%. The -3dB audio response from the volume control to the speaker is 260-4600Hz, with a peak of about +4dB at 1050Hz. From the antenna to the speaker, it’s 150-1900Hz. For a +6dB output rise, the signal increase was around +25dB, about as good as can be expected with the simple AGC used in the APN. It went into signal overload at around 25mV/m, which is a strong signal. -3dB selectivity is ±2.5kHz; for -40dB, it’s ±14.5kHz. This selectivity compares well with the 897’s figure of ±13kHz at -60dB, allowing for the 897’s double-tuned IF transformers. I tested it at only -40dB because much over this put the APN’s converter into overload. It gave reliable results at -40dB, and the ±14.5kHz skirt selectivity is enough to reduce interference from any adjacent channel radio station. Its low battery performance is good. Although its sensitivity reduces with a supply voltage of 5.5V, it still exceeded 50mW output with low distortion. This low distortion justifies my bias diode replacement for the failed voltage divider/thermistor circuit. Purchase recommendations I’m looking for a good original case with a wrecked chassis to de-­ Frankenstein my example (see Photo 5). If you have AWA’s 897 in your collection and don’t have an APN, consider getting one. It’s a bit smaller, with – to me – a more interesting visual design. As an engineer, I appreciate its comparable performance to that of the AWA, especially given that it has one less amplifying stage. Jim Greig restored a genuine APN (described in the HRSA Radio Waves magazine, October 2020) and found similar faults to mine. Jim’s method of fault-finding is a valuable reminder that different repairers use the basic principles differently. According to the Radio Waves article in January 2023 referenced earlier, Geoff and Jim have only discovered one issue of this radio, in the red case (see the lead photo). So if you see an APN in a different case, it’s likely another Frankenstein’s monster. Special handling The tuning and volume knobs are a press fit onto the capacitor shaft. I recommend that you don’t use screwdrivers or other levers to remove them. I was able to use finger pressure; if you can’t get them off that way, run strings under the knobs and use a gentle pull SC to remove them. Photo 5: my ‘Frankenstein’ Astor APN came in a leather case originally for a similar valve set. It is different from the ‘original’ red leather case shown in the lead photo. siliconchip.com.au Australia's electronics magazine May 2023  105 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. 05/23 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. 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Just add a signal source, case, power supply and wiring $100.00 siliconchip.com.au/Shop/ RASPBERRY PI PICO W BACKPACK Complete kit: includes all parts in the parts list, except the DS3231 real-time clock IC (Cat SC6625; see page 56, January 2023) - DS3231 real-time clock SOIC-16 IC (Cat SC5103) - DS3231MZ real-time clock SOIC-8 IC (Cat SC5779) DUAL-CHANNEL BREADBOARD PSU (JAN 23) $85.00 $7.50 $10.00 (DEC 22) Power Supply kit: complete kit with a choice of red + green, yellow + cyan or orange + white knob colours (Cat SC6571; see page 38, December 2022) Display Adaptor kit: complete kit (Cat SC6572; see page 45, December 2022) $40.00 $50.00 DIGITAL BOOST REGULATOR KIT (CAT SC6597) (DEC 22) LC METER MK3 (NOV 22) NEW GPS(/WIFI)-SYNCHRONISED ANALOG CLOCK (SEP & NOV 22) BUCK/BOOST CHARGER ADAPTOR KIT (CAT SC6512) (OCT 22) WiFi PROGRAMMABLE DC LOAD (SEP 22) Complete kit that also includes all optional components (see page 87, Dec22) Short Form Kit: includes the PCB and all non-optional onboard parts, except the case, front panel label and power supply (Cat SC6544) $30.00 $65.00 GPS-version kit: includes everything in the parts list with the VK2828 GPS module (Cat SC6472; see September 2022 p63) $55.00 WiFi-version kit: includes everything in the parts list with the D1 Mini module instead (Cat SC6472; D1 Mini is supplied not programmed, see November 2022 p76) $55.00 Includes everything in the parts list (see page 64, October 2022) except the Buck/Boost LED Driver (Cat SC6292) $40.00 Short Form Kit: includes all SMDs, the power Mosfets, four 0.02W 3W resistors and the VXO7805 regulator module (Cat SC6399) - laser-cut 3mm clear acrylic side panel (SC6514) - 3.5-inch TFT LCD touchscreen (Cat SC5062) VGA PICOMITE KIT (CAT SC6417) (JUL 22) MULTIMETER CALIBRATOR KIT (CAT SC6406) (JUL 22) $85.00 $7.50 $35.00 Complete kit with everything needed to assemble the board, you just require a few external parts such as a power supply, keyboard and monitor $35.00 Complete kit with everything needed to assemble the board *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. $45.00 PRINTED CIRCUIT BOARDS & CASE PIECES PRINTED CIRCUIT BOARD TO SUIT PROJECT H-FIELD TRANSANALYSER CAR ALTIMETER RCL BOX RESISTOR BOARD ↳ CAPACITOR / INDUCTOR BOARD ROADIES’ TEST GENERATOR SMD VERSION ↳ THROUGH-HOLE VERSION COLOUR MAXIMITE 2 PCB (BLUE) ↳ FRONT & REAR PANELS (BLACK) OL’ TIMER II PCB (RED, BLUE OR BLACK) ↳ ACRYLIC CASE PIECES / SPACER (BLACK) IR REMOTE CONTROL ASSISTANT PCB (JAYCAR) ↳ ALTRONICS VERSION USB SUPERCODEC ↳ BALANCED ATTENUATOR SWITCHMODE 78XX REPLACEMENT WIDEBAND DIGITAL RF POWER METER ULTRASONIC CLEANER MAIN PCB ↳ FRONT PANEL NIGHT KEEPER LIGHTHOUSE SHIRT POCKET AUDIO OSCILLATOR ↳ 8-PIN ATtiny PROGRAMMING ADAPTOR D1 MINI LCD WIFI BACKPACK FLEXIBLE DIGITAL LIGHTING CONTROLLER SLAVE ↳ FRONT PANEL (BLACK) LED XMAS ORNAMENTS 30 LED STACKABLE STAR ↳ RGB VERSION (BLACK) DIGITAL LIGHTING MICROMITE MASTER ↳ CP2102 ADAPTOR BATTERY VINTAGE RADIO POWER SUPPLY DUAL BATTERY LIFESAVER DIGITAL LIGHTING CONTROLLER LED SLAVE BK1198 AM/FM/SW RADIO MINIHEART HEARTBEAT SIMULATOR I’M BUSY GO AWAY (DOOR WARNING) BATTERY MULTI LOGGER ELECTRONIC WIND CHIMES ARDUINO 0-14V POWER SUPPLY SHIELD HIGH-CURRENT BATTERY BALANCER (4-LAYERS) MINI ISOLATED SERIAL LINK REFINED FULL-WAVE MOTOR SPEED CONTROLLER DIGITAL FX UNIT PCB (POTENTIOMETER-BASED) ↳ SWITCH-BASED ARDUINO MIDI SHIELD ↳ 8X8 TACTILE PUSHBUTTON SWITCH MATRIX HYBRID LAB POWER SUPPLY CONTROL PCB ↳ REGULATOR PCB VARIAC MAINS VOLTAGE REGULATION ADVANCED GPS COMPUTER PIC PROGRAMMING HELPER 8-PIN PCB ↳ 8/14/20-PIN PCB ARCADE MINI PONG Si473x FM/AM/SW DIGITAL RADIO 20A DC MOTOR SPEED CONTROLLER MODEL RAILWAY LEVEL CROSSING COLOUR MAXIMITE 2 GEN2 (4 LAYERS) BATTERY MANAGER SWITCH MODULE ↳ I/O EXPANDER NANO TV PONG LINEAR MIDI KEYBOARD (8 KEYS) + 2 JOINERS ↳ JOINER ONLY (1pc) TOUCHSCREEN DIGITAL PREAMP ↳ RIBBON CABLE / IR ADAPTOR 2-/3-WAY ACTIVE CROSSOVER TELE-COM INTERCOM SMD TEST TWEEZERS (3 PCB SET) USB CABLE TESTER MAIN PCB ↳ FRONT PANEL (GREEN) MODEL RAILWAY CARRIAGE LIGHTS HUMMINGBIRD AMPLIFIER DIGITAL LIGHTING CONTROLLER TRANSLATOR SMD TRAINER 8-LED METRONOME DATE MAY20 MAY20 JUN20 JUN20 JUN20 JUN20 JUL20 JUL20 JUL20 JUL20 JUL20 JUL20 AUG20 NOV20 AUG20 AUG20 SEP20 SEP20 SEP20 SEP20 SEP20 OCT20 OCT20 OCT20 NOV20 NOV20 NOV20 NOV20 NOV20 DEC20 DEC20 DEC20 JAN21 JAN21 JAN21 FEB21 FEB21 FEB21 MAR21 MAR21 APR21 APR21 APR21 APR21 APR21 MAY21 MAY21 MAY21 JUN21 JUN21 JUN21 JUN21 JUL21 JUL21 JUL21 AUG21 AUG21 AUG21 AUG21 AUG21 AUG21 SEP21 SEP21 OCT21 OCT21 OCT21 NOV21 NOV21 NOV21 DEC21 DEC21 DEC21 JAN22 PCB CODE 06102201 05105201 04104201 04104202 01005201 01005202 07107201 SC5500 19104201 SC5448 15005201 15005202 01106201 01106202 18105201 04106201 04105201 04105202 08110201 01110201 01110202 24106121 16110202 16110203 16111191-9 16109201 16109202 16110201 16110204 11111201 11111202 16110205 CSE200902A 01109201 16112201 11106201 23011201 18106201 14102211 24102211 10102211 01102211 01102212 23101211 23101212 18104211 18104212 10103211 05102211 24106211 24106212 08105211 CSE210301C 11006211 09108211 07108211 11104211 11104212 08105212 23101213 23101214 01103191 01103192 01109211 12110121 04106211/2 04108211 04108212 09109211 01111211 16110206 29106211 23111211 Price $10.00 $5.00 $7.50 $7.50 $2.50 $5.00 $10.00 $10.00 $5.00 $7.50 $5.00 $5.00 $12.50 $7.50 $2.50 $5.00 $7.50 $5.00 $5.00 $2.50 $1.50 $5.00 $20.00 $20.00 $3.00 $12.50 $12.50 $5.00 $2.50 $7.50 $2.50 $5.00 $10.00 $5.00 $2.50 $5.00 $10.00 $5.00 $12.50 $2.50 $7.50 $7.50 $7.50 $5.00 $10.00 $10.00 $7.50 $7.50 $7.50 $5.00 $7.50 $35.00 $7.50 $7.50 $5.00 $15.00 $5.00 $2.50 $2.50 $5.00 $1.00 $12.50 $2.50 $15.00 $30.00 $10.00 $7.50 $5.00 $2.50 $5.00 $5.00 $5.00 $5.00 For a complete list, go to siliconchip.com.au/Shop/8 PRINTED CIRCUIT BOARD TO SUIT PROJECT 10-LED METRONOME REMOTE CONTROL RANGE EXTENDER UHF-TO-IR ↳ IR-TO-UHF 6-CHANNEL LOUDSPEAKER PROTECTOR ↳ 4-CHANNEL FAN CONTROLLER & LOUDSPEAKER PROTECTOR SOLID STATE TESLA COIL (SET OF 2 PCBs) REMOTE GATE CONTROLLER DUAL HYBRID POWER SUPPLY SET (2 REGULATORS) ↳ REGULATOR ↳ FRONT PANEL ↳ CPU ↳ LCD ADAPTOR ↳ ACRYLIC LCD BEZEL RASPBERRY PI PICO BACKPACK AMPLIFIER CLIPPING DETECTOR CAPACITOR DISCHARGE WELDER POWER SUPPLY ↳ CONTROL PCB ↳ ENERGY STORAGE MODULE (ESM) PCB 500W AMPLIFIER MODEL RAILWAY SEMAPHORE CONTROL PCB ↳ SIGNAL FLAG (RED) AM-FM DDS SIGNAL GENERATOR SLOT MACHINE HIGH-POWER BUCK-BOOST LED DRIVER ARDUINO PROGRAMMABLE LOAD SPECTRAL SOUND MIDI SYNTHESISER REV. UNIVERSAL BATTERY CHARGE CONTROLLER VGA PICOMITE SECURE REMOTE MAINS SWITCH RECEIVER ↳ TRANSMITTER (1.0MM THICKNESS) MULTIMETER CALIBRATOR 110dB RF ATTENUATOR WIDE-RANGE OHMMETER WiFi PROGRAMMABLE DC LOAD MAIN PCB ↳ DAUGHTER BOARD ↳ CONTROL BOARD MINI LED DRIVER NEW GPS-SYNCHRONISED ANALOG CLOCK BUCK/BOOST CHARGER ADAPTOR 30V 2A BENCH SUPPLY MAIN PCB ↳ FRONT PANEL CONTROL PCB AUTO TRAIN CONTROLLER ↳ TRAIN CHUFF SOUND GENERATOR PIC16F18xxx BREAKOUT BOARD (DIP-VERSION) ↳ SOIC-VERSION AVR64DD32 BREAKOUT BOARD LC METER MK3 ↳ ADAPTOR BOARD DC TRANSIENT SUPPLY FILTER TINY LED ICICLE (WHITE) DUAL-CHANNEL BREADBOARD PSU ↳ DISPLAY BOARD DIGITAL BOOST REGULATOR ACTIVE MONITOR SPEAKERS POWER SUPPLY PICO W BACKPACK Q METER MAIN PCB ↳ FRONT PANEL (BLACK) NOUGHTS & CROSSES COMPUTER GAME BOARD ↳ COMPUTE BOARD ACTIVE MAINS SOFT STARTER ADVANCED SMD TEST TWEEZERS SET DIGITAL VOLUME CONTROL POT (SMD VERSION) ↳ THROUGH-HOLE VERSION MODEL RAILWAY TURNTABLE CONTROL PCB ↳ CONTACT PCB (GOLD-PLATED) WIDEBAND FUEL MIXTURE DISPLAY (BLUE) TEST BENCH SWISS ARMY KNIFE (BLUE) SILICON CHIRP CRICKET DATE JAN22 JAN22 JAN22 JAN22 JAN22 FEB22 FEB22 FEB22 FEB22 FEB22 FEB22 FEB22 FEB22 FEB22 MAR22 MAR22 MAR22 MAR22 MAR22 APR22 APR22 APR22 MAY22 MAY22 JUN22 JUN22 JUN22 JUN22 JUL22 JUL22 JUL22 JUL22 JUL22 AUG22 SEP22 SEP22 SEP22 SEP22 SEP22 OCT22 OCT22 OCT22 OCT22 OCT22 OCT22 OCT22 OCT22 NOV22 NOV22 NOV22 NOV22 DEC22 DEC22 DEC22 DEC22 JAN23 JAN23 JAN23 JAN23 JAN23 FEB23 FEB23 MAR23 MAR23 MAR23 MAR23 APR23 APR23 APR23 PCB CODE 23111212 15109211 15109212 01101221 01101222 01102221 26112211/2 11009121 SC6204 18107211 18107212 01106193 01106196 SC6309 07101221 01112211 29103221 29103222 29103223 01107021 09103221 09103222 CSE211002 08105221 16103221 04105221 01106221 04107192 07107221 10109211 10109212 04107221 CSE211003 04109221 04108221 04108222 18104212 16106221 19109221 14108221 04105221 04105222 09109221 09109222 24110222 24110225 24110223 CSE220503C CSE200603 08108221 16111192 04112221 04112222 24110224 01112221 07101221 CSE220701 CSE220704 08111221 08111222 10110221 04106221/2 01101231 01101232 09103231 09103232 05104231 04110221 08101231 GPS DISCIPLINED OSCILLATOR SONGBIRD (RED, GREEN, PURPLE or YELLOW) DUAL RF AMPLIFIER (GREEN or BLUE) MAY23 MAY23 MAY23 04103231 $5.00 08103231 $4.00 CSE220602A $2.50 NEW PCBs Price $7.50 $2.50 $2.50 $7.50 $5.00 $5.00 $7.50 $20.00 $25.00 $7.50 $2.50 $5.00 $2.50 $5.00 $5.00 $2.50 $5.00 $5.00 $5.00 $25.00 $2.50 $2.50 $7.50 $5.00 $5.00 $5.00 $7.50 $7.50 $5.00 $7.50 $2.50 $5.00 $5.00 $7.50 $7.50 $5.00 $10.00 $2.50 $5.00 $5.00 $7.50 $2.50 $2.50 $2.50 $2.50 $2.50 $2.50 $7.50 $2.50 $5.00 $2.50 $5.00 $5.00 $5.00 $10.00 $5.00 $5.00 $5.00 $12.50 $12.50 $10.00 $10.00 $2.50 $5.00 $5.00 $10.00 $10.00 $10.00 $5.00 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 Advanced Test Tweezers won’t power up I built the Advanced SMD Test Tweezers (February & March 2023; siliconchip.au/Series/396) from a kit. After inserting the cell, the screen was dead, so I went back to do some diagnostics. I checked the voltages at relevant outputs to the screen, which all measured 0V. I then checked the connectivity of the parts and discovered that I was getting continuity between the + and – terminals of the cell holder without the cell in the holder. Could I have a faulty circuit board? (P. G., Springwood, Qld) ● A faulty circuit board is very unlikely; the clearances in the design are very conservative. More likely, it is a short circuit between the battery terminals or some other point connected to the battery terminals, such as the microcontroller. Given the fine pitch of the microcontroller pins, you should look for bridged pins around the microcontroller. Some supply pins are next to ground pins, so a bridge between them would give continuity across the cell holder. If you send us some close-up photos, we can look to see if there is anything else you might have missed. Advanced Test Tweezers cell polarity Please confirm that the coin cell battery should be negative to the board for the Advanced SMD Test Tweezers. Would the device be damaged by a cell inserted with reversed polarity? My ageing eyesight is becoming a problem for constructing in fine detail. I think I can see a + on the contact tag of the battery holder. (B. W., Cornubia, Qld) ● Yes, the negative contact is the PCB pad, while the positive contacts are the springs on the cell holder. If the cell were reversed, there would effectively be a short circuit via IC1’s internal protection diodes. That could exceed the maximum current 108 Silicon Chip and voltage ratings, even with the limited current that the coin cell can provide. So it’s possible that IC1 could be damaged. There is also the possibility that the cell would be short-circuited against the sides and top of the holder when installed in reverse; if you’re lucky and that happened, it could have prevented damage. In the cases where we have seen damaged chips, they seemed to suffer from excess current in sleep mode. You would notice this as the Tweezers’ coin cell going flat quickly (within days to a week). Obtaining a dual gang 500W potentiometer I am trying to repair a Solidyne Studiobox HD3 headphone unit that has developed very noisy pots, but I am having difficulty sourcing replacement potentiometers. I tried contact cleaner spray but it did not help. I need two 500W linear taper dualgang rotary potentiometers with 16mm diameter bases and 6mm splined shafts. I also need one 10kW logarithmic taper dual-gang pot of the same physical size, but those are easier to find. The Taiwan Alpha Electronic Co Ltd manufactures these pots but their minimum order quantity is 1000 units. Their order code for these pots is RV16A01F-30, but I could also make the RV16A01F-20 work in the headphone box. I have tried contacting a couple of Alpha distributors but have yet to receive a response from them. If you can advise where I might be able to purchase a couple of these 500W dualgang potentiometers, it would be much appreciated. (G. B., New Plymouth, New Zealand) ● You could try Altronics for the 16mm pots. They sell 10kW dual-gang pots but don’t have 500W values. However, they also sell single-gang 500W pots (catalog code R2222). By disassembling two 500W single-ganged Australia's electronics magazine pots, you could obtain resistance elements to install into dual-gang pots in place of the 10kW elements supplied. Compiling software for 3D-printed Robotic Arm I am building the 3D-printed Robotic Arm from Circuit Notebook, March 2023 (siliconchip.au/Article/15707). I downloaded the Arduino software, but when I load the INO file into the Arduino IDE and try to upload it, I get an error regarding the “Fonts/FreeSandsBold12pt7b.h” library. I am using the latest IDE, version 2.0.4. Can you assist in pointing me to the location of these library files? (J. A., Townsville, Qld) ● That font (and the others used in the design) is part of the Adafruit_GFX library. You need to install, at a minimum, the following libraries: • Adafruit_GFX • Adafruit_TouchScreen • MCUFRIEND_kbv • Servo You should be able to install those via the Arduino IDE library manager. Breadboard Power Supply queries I just built the Dual-Channel Breadboard Power Supply and Display (December 2022 issue; siliconchip. au/Article/15577), and it works quite well, but I noticed that the voltage adjustment is only over half the range of the pot. The display shows a target of around 30V at full potentiometer rotation, but it can only ever get to around 13V due to the supply constraints. The above behaviour seems correct for the resistive divider of 51kW/10kW. Wouldn’t it have been better to choose a divider to use the whole of the pot’s rotation? Also, would it not have been better to use blocking diodes to have a choice of USB via the booster or the jack supply rather than the complexity of jumpers? The 5V could then just be fed from the regulator for both siliconchip.com.au situations, and the jumpers could be done away with. ● For the Breadboard PSU, we borrowed much of the design from the Arduino PSU from the February 2021 issue (siliconchip.au/Series/357). It looks pretty straightforward, but we did a lot of testing to validate that the design was stable and decided it was best not to change it too much. We also thought that some constructors might choose to use parts with higher voltage ratings to get an output closer to 30V, but we left that as an exercise for the reader. We found that the boost module struggled to deliver much current, and feeding the supply through diodes would only worsen that. We don’t use the boost module much because of that, but we left it in the design as it should be fine for when you don’t need that much current (as is often the case when breadboarding). You should be able to add a diode in place of JP1 to achieve what you are considering. It should fit in the available space if mounted vertically. Use a schottky diode to minimise losses and connect the anode of the diode to the output of the boost regulator (rightmost pin on top half of Fig.2), with the cathode to the other two pins (leftmost and centre pin). We would leave JP2 at the REG position to make use of the more stable 5V supply from REG1. Sourcing parts to build the CD Welder Do you sell a complete kit for the Capacitor Discharge Welder (March & April 2022; siliconchip.au/Series/379) with all components as pictured in the magazine? (D. L., The Ponds, NSW) ● There is no complete kit, but we can supply some of the parts. All our kits are listed online: siliconchip.au/ Shop/20 We have a partial kit for the ESM that includes everything for one ESM except the capacitors: siliconchip.au/ Shop/20/6225 We also have a kit for the power supply that includes the power supply PCB and all components that mount on it: siliconchip.au/Shop/20/6224 We also sell the control PCB: siliconchip.au/Shop/8/6272 The majority of the remaining parts you would have to get are the capacitors, the components that mount on the control PCB, the case, the bus bars, wiring and other hardware to complete the Welder. Tables 1 & 2 in the article list sources for the capacitors. The case comes from Altronics, and they would also have all the control PCB components, the wiring and most of the other components. That just leaves the aluminium bus bars, which you could get from eBay, some hardware stores and some hobby shops. Replacing ceiling fan speed control capacitor I have a ceiling fan that no longer works on slow speed; I dismantled the speed controller/remote receiver and found the run capacitor for slow speed extremely low capacity. I assume that on low speed, it only uses the ‘195K’ capacitor, on medium, the ‘215K’ and for high speed, both in parallel; I cannot see any circuitry bypassing them. The MKP capacitor marked “215K5300VAC” seems OK. The MKP capacitor marked “195K300VAC” seems to have failed, and I cannot find a replacement anywhere. Can you TEST MANY COMPONENTS ITH OUR ADVANCED TEST T EEZERS The Advanced Test Tweezers have 10 different modes, so you can measure ❎ Resistance: 1Ω to 40MΩ, ±1% ❎ Capacitance: 10pF to 150μF, ±5% ❎ Diode forward voltage: 0-2.4V, ±2% ❎ Combined resistance/ capacitance/diode display ❎ Voltmeter: 0 to ±30V ±2% ❎ Oscilloscope: ranges ±30V at up to 25kSa/s ❎ Serial UART decoder ❎ I/V curve plotter ❎ Logic probe ❎ Audio tone/square wave generator It runs from a single CR2032 coin cell, ~five years of standby life Has an adjustable sleep timeout Adjustable display brightness The display can be rotated for leftand right-handed use Components can be measured in-circuit under some circumstances Complete kit for $45 (SC6631; siliconchip.com.au/Shop/20/6631) The kit includes everything pictured, except the lithium coin cell and optional programming header. See the series of articles in the February & March 2023 issues for more details (siliconchip.com.au/Series/396). siliconchip.com.au Australia's electronics magazine May 2023  109 suggest a part and where it could be obtained? (G. H., Littlehampton, SA) ● We can’t find that exact capacitor, but we think you could substitute a 1.8µF 500V AC rated MKP capacitor from element14. Note that it has a different shape and may not fit in the space required: https://au.element14. com/4049126 Pump motor capacitor failure My spa pump motor stopped working. When I checked it, I found it had two capacitors, 16µF and 25µF. The 25µF had spectacularly blown itself up. I replaced both on principle, the 16µF with a 15µF, as that was what was available. I assumed the 25µF was the start capacitor and the 16µF was the run capacitor. However, the motor has two speeds, and now the slow speed runs for a second only when turned on. The fast speed does work. Do you know how a single-phase induction motor works at two different speeds? Would the 16µF (15µF) capacitor be shorted out at high speed or open-circuit at low speed? The repair person, who has been very helpful via texts, says the motor needs replacing. It obviously is not burnt out, as the odour of burnt-out electric equipment is impossible to miss, even weeks later. Could the new capacitor having a value of 15µF instead of 16µF stop it from working? They are 5% tolerance parts, and a 1µF difference is only -6.25% (or -6.6% if on the low end of its tolerance range). (J. B., Northgate, Qld) 110 Silicon Chip Hummingbird Amplifier power supply and speaker protector Can I use the Altronics Cat K5168 Power Supply Board and Cat K5167 Stereo Speaker Protector Board for 135W Ultra LD Amplifier with the Hummingbird power amplifier (December 2021 issue; siliconchip.au/Article/15126)? ● Yes, you can use those boards as long as they are teamed up with a suitable transformer. If your amplifier will only have one or two channels, that speaker protector should be fine. If building three or more Hummingbird modules, consider our recent MultiChannel Speaker Protector that handles up to six channels on a single PCB (January 2022; siliconchip.au/Article/15171). ● There could be a fault in one of the windings that causes it to go open-­ circuit when the temperature rises. The 15µF capacitor should not affect the operation compared to 16µF. Commonly, a single-phase induction motor has a capacitor in series with a second winding to provide a phase shift so the motor can start and run. Presumably, one of these capacitors is for the phase-shift winding, and the other is for low-speed operation. The expected arrangement depends on the configuration of the motor windings and design. The diagram shown below some common single-phase induction motor winding configurations in case that helps. DCC Booster baulking at buck converter load I have successfully used your DCC Controller/Booster (January 2020; siliconchip.au/Article/12220) as both a booster and a DCC controller. I’m currently working on a loco presence detection circuit, and I need to derive 5V from the DCC power bus. I’m trying to do this by full-wave rectifying Australia's electronics magazine the bus and feeding the derived DC to a buck converter. The buck converter works fine when I drive it from a variable DC supply; it appears to draw about 20mA momentarily, then settles down to 10mA. When connected to the DCC Booster, the buck converter ‘motorboats’ with the LEDs alternating between green and red. I looked at the Booster Arduino code and noticed that the current trip limit is set to 120. However, there is no comment in the code to say how to interpret that value; it could be a simple decimal equivalent of a binary value. I think the problem is that the Booster sees the buck converter as a momentary short. How do I adjust the trip limit to get more current? The buck converter is a Jaycar XC4514, which uses the LM2956S chip. Thanks for your help. (B. P., Jeir, NSW) ● We think you are right that the Booster sees the capacitors on the buck converter as a short circuit until they charge up. The Booster sketch (“DCC_Shield_ passthrough_supervisor.ino”) uses raw ADC values while the sketch name “DCC_Single_Loco_Control.ino” displays in amps. This was tuned with our prototype. You could try using those values, but they might not be accurate. We calculate that a value of 120 corresponds to around 1.7A on our prototype, but yours could differ. The actual current calculation depends on the characteristics of the BTN8962 devices (which provide the current sensing feature), as they source a current proportional to the output current but with an offset. The offset current can vary from 50µA to 440µA, and the ratio can vary from one part in 7200 to one part in 12800 of the output current. That’s quite a bit of variation. The tolerance of the 1kW resistor and the Arduino 5V regulator will also add some variation. Assuming your continued on page 112 siliconchip.com.au MARKET CENTRE Advertise your product or services here in Silicon Chip KIT ASSEMBLY & REPAIR FOR SALE DAVE THOMPSON (the Serviceman from Silicon Chip) is available to help you with kit assembly, project troubleshooting, general electronics and custom design work. No job too small. Based in Christchurch, New Zealand, but service available Australia/NZ wide. Email dave<at>davethompson.co.nz LEDsales KEITH RIPPON KIT ASSEMBLY & REPAIR: * Australia & New Zealand; * Small production runs. Phone Keith: 0409 662 794 keith.rippon<at>gmail.com LEDs and accessories for the DIY enthusiast LEDs, BRAND NAME AND GENERIC LEDs. Heatsinks, LED drivers, power supplies, LED ribbon, kits, components, hardware – www.ledsales.com.au VISIT THE NEW TRONIXLABS parts clearance store for real savings on new parts at clearance prices, with flat rate express delivery Australia-wide – go to https://tronixlabs.com Lazer Security PCB PRODUCTION PCB MANUFACTURE: single to multilayer. Bare board tested. One-offs to any quantity. 48 hour service. Artwork design. Excellent prices. Check out our specials: www.ldelectronics.com.au For Quality That Counts... QUALITY COMPONENTS + MORE The parts clearance sale continues, but stock is limited, this month check out the freebies – go to lazer.com.au FOR SALE OATLEY ELECTRONICS www.oatleyelectronics.com APRIL SPECIALS, search for "ITXX" on our website: * 10 x 12V / 0.5m LED Bars $18 (“IT117PW”) * 12V-5W Lamp Package Four 12V-5W LED lamps, two E27 lamp bases + two bayonet adaptors for $17 (“IT157”) * Geiger Counter Kit Military case plus a Geiger module for $90 (“IT163”) We will quote you a low shipping rate, address and potential order required. www.oatleyelectronics.com branko<at>oatleyelectronics.com Phone: 0428600036 ASSORTED BOOKS FOR $5 EACH Electronics and other related subjects – condition varies. Some of the books may have been sold. See photos (recently updated): siliconchip.au/link/abl3 Email for a quote (bulk discount available), state the number directly below the photo when referring to a book: silicon<at>siliconchip.com.au ADVERTISING IN MARKET CENTRE Classified Ad Rates: $32.00 for up to 20 words (punctuation not charged) plus $1.20 for each additional word. Display ads in Market Centre (minimum 2cm deep, maximum 10cm deep): $82.50 per column centimetre per insertion. All prices include GST. Closing date: 5 weeks prior to month of sale. To book, email the text to silicon<at>siliconchip.com.au and include your name, address & credit card details, or phone (02) 9939 3295 or 0431 792 293. WARNING! Silicon Chip magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of Silicon Chip magazine. Devices or circuits described in Silicon Chip may be covered by patents. Silicon Chip disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. Silicon Chip also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. siliconchip.com.au Australia's electronics magazine May 2023  111 Advertising Index Altronics.................................35-42 Control Devices........................... 51 Dave Thompson........................ 111 Digi-Key Electronics...................... 3 ElectroneX................................... 17 element14................................OBC Emona Instruments.................. IBC Hare & Forbes............................. 47 Icom Australia............................. 13 Jaycar.................IFC, 11, 15, 18-19, ................................... 93, 95, 97, 99 Keith Rippon Kit Assembly....... 111 Lazer Security........................... 111 LD Electronics........................... 111 LEACH PCB Assembly................ 55 LEDsales................................... 111 Mastercut Technologies............. 16 Microchip Technology............ 7, 71 Mouser Electronics....................... 4 Oatley Electronics..................... 111 Rohde & Schwarz.......................... 9 SC Raspberry Pi Pico W............. 46 Silicon Chip Shop............ 106-107 Silicon Chip Subscriptions........ 72 Silicon Chip Test Tweezers..... 109 The Loudspeaker Kit.com.......... 12 Tronixlabs.................................. 111 Wagner Electronics....................... 8 Errata and Next Issue _____________ Active Mains Soft Starter, February & March 2023: the right-hand column on page 71 of the March issue says to use red or black wire for Active. It should have said red or brown. Next Issue: the June 2023 issue is due on sale in newsagents by Monday, May 29th. Expect postal delivery of subscription copies in Australia between May 26th and June 12th. 112 Silicon Chip unit is similar to ours, a reading of 84 ADC steps corresponds to 0A, with 21 more steps per additional amp; ie, 105 means 1A, 126 means 2A, 147 means 3A etc. We recommend adding a line “Serial.println(p);” to the main sketch loop() function; p is the sampled current sense analog value. This will allow you to quickly check the calibration of your unit as you apply test loads and possibly increase the current limit with safety. A simple fix might be to use a single-­ diode rectifier, which should reduce the inrush current by half. If the load on the converter is relatively low, a series resistor might work to limit the inrush current at the cost of dissipation in the resistor. An NTC thermistor rated at a few amps would be even better but more expensive. Since the DCC signal is an AC source, you could also use a capacitor (in series) dropper. Simulations suggest that values around 100nF to 1µF in one of the AC legs from the DCC signal (ie, before the bridge) might be in the workable range for the 220µF capacitor on the XC4514 buck converter. Still, it will depend on the load on your buck converter. Choosing a transformer for the Class-A amp The Altronics transformer specified for the 20W Class-A Amplifier (May-September 2007; siliconchip.au/ Series/58) is listed as 16-0-16V AC. I have an 18-0-18V AC transformer on hand. Is it OK to use this? If so, would I need to change any circuit values? (R. H., Berowra Heights, NSW) ● An 18-0-18V transformer would result in a higher DC voltage than the amplifier is designed for, and it isn’t easy to change it to handle that. You can use your transformer if you backwind the secondaries until you get an output closer to 16V AC for each. If you can’t get the 16-0-16 transformer, a 15-0-15 transformer might be available and would only reduce the output power slightly. Fixing the Automatic Rain Gauge Many years ago (in 2000), I built your tipping bucket rain gauge (June 2000; siliconchip.au/Article/4325), and it has been working without fail Australia's electronics magazine until recently. Now it wouldn’t record rainfall. I have diagnosed the fault to be the IR sensor in the bucket assembly. Not having the original documentation that came with it, I am stuck as to what the part is, but I have a bucket assembly from a failed Bunnings wireless unit. This bucket uses a reed switch and magnet. Would it be possible to get a copy of the circuit diagram so I can investigate if it’s possible to use a reed switch assembly? (C. L., Allingham, Qld) ● The sensor used in the Rain Gauge was the Jaycar Z1901 photo interruptor, which is still available. We still have plenty of June 2000 back issues if you need the circuit diagram, or you can get online access, via the following links: Print: siliconchip.au/ Shop/2/319; Digital: siliconchip.au/ Shop/12/3138 Replacing the sensor with a reed switch is easily possible. Just connect the reed switch between pin 6 of IC1 and circuit ground. That is the same connections as for the photo interruptor phototransistor collector (pin 6) and emitter (GND). If the bucket assembly from the Bunnings wireless unit tips the bucket each time it collects 1mm of rain, it should work with the Rain Gauge. Our Rain Gauge had an 86mm diameter collection area, so the volume of water collected for 1mm of rain is 5.808cm3 or 5.808mL (π × 43mm2 × 1mm). Optocoupler transistor base connection What do you connect the phototransistor base to when using an optocoupler like the 4N25, 4N26, 4N27 or 4N28? Leave it open, connect it to ground? (F. C., Maroubra, NSW) ● Generally, the base is left open. A resistor can be added between the base and the emitter to speed up the output response. This allows the transistor to switch off faster in the absence of light. However, it also reduces the sensitivity of the optocoupler, so more input current is required to switch on the output transistor. Care should be taken not to exceed the LED’s current ratings. When using a base resistor, its value is a compromise between output switch-off speed and input sensitivity. 10kW could be a good starting point. For more information, visit: siliconchip.au/link/abl5 SC siliconchip.com.au “Rigol Offer Australia’s Best Value Test Instruments” Oscilloscopes NEW 200MHz $649! New Product! 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