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Advertising Index Altronics.................................85-88 Ampec Technologies.................... 5 Dave Thompson........................ 111 Dick Smith Contest....................... 9 Digi-Key Electronics...................... 3 Emona Instruments.................. IBC Jaycar.............................. IFC,53-60 Keith Rippon Kit Assembly....... 111 Lazer Security........................... 111 LD Electronics........................... 111 LEDsales................................... 111 Microchip Technology.................. 7 Mouser Electronics..................OBC Ocean Controls............................. 6 PMD Way................................... 111 SC SMD Test Tweezers.............. 77 SC USB Cable Tester................ 105 Silicon Chip Binders.................. 51 Silicon Chip Subscriptions........ 11 Silicon Chip Shop............ 106-107 Silicon Chip RTV&H DVD......... 109 Switchmode Power Supplies....... 8 The Loudspeaker Kit.com.......... 95 Tronixlabs.................................. 111 Vintage Radio Repairs.............. 111 Wagner Electronics..................... 10 and a complete oversight on my part. My question is, could this have been the cause for all the output devices to self-destruct? I have since connected the Earth wire from the mains socket to the power supply. I think that, as the amp worked well during my initial testing, it probably doesn’t have any incorrectly placed components or dry solder joints. I was very meticulous in the soldering and placing of components. Do you know what might have gone wrong? (P. S., Mount Pleasant, SA) ● It is possible that not having the mains Earth to the amplifier could have caused the destruction, but it seems a bit unlikely. Have you checked what happens to the output from the signal generator when switching frequency? Does the output initially clip on one half of the cycle that could cause the amplifier to have a DC offset for a short period, which could cause an overload that destroys the transistors? There is AC coupling on the amplifier input, but it may not be enough to save the amplifier if that happens. You could check what happens with no load on the amplifier, as that shouldn’t cause the amplifier to blow even if there is a significant DC pulse. Modern car radio antennas aren’t good I have a 2018 Volkswagen with a short 20cm roof-mounted aerial and the radio is full of hash when driving near railways and power lines. Is there a better replacement aerial or accessory to improve reception? Would ferrite rings over the aerial make a difference? (M. P., Croydon, Vic) ● The problem is probably due to Notes & Errata SMD Trainer, December 2021: The parts list and kit for the SMD Trainer Board only lists two 100nF capacitors when three are shown on the schematic and PCB. The kit has been updated, but those who have already received kits should note that the circuit will most likely work correctly without the 100nF capacitor below IC2. Hummingbird Amplifier Module, December 2021: in Fig.7 on p23, the “E” & “B” labels for Q12 have been swapped. In the body text of p23, MLJ15032/33 should read MJE15032/33. Pocket Weather Station, November 2021: in Fig.2 the DAT connection from the DHT11 should connect to pin D4 of the Arduino Nano, not D5. The February 2022 issue is due on sale in newsagents by Thursday, January 27th. Expect postal delivery of subscription copies in Australia between January 26th and February 11th. 112 Silicon Chip Australia's electronics magazine low-amplitude radio signals making their way to the radio’s antenna input. This could be due to bad connections, especially if you live near the sea. Make sure that all connections from the antenna to the radio are clean and undamaged. This would require removing the radio to check the antenna connection at the rear and also removing the antenna. Any ferrite ring over the antenna would likely reduce the antenna radio reception and detune the antenna. Alternatively, there may be a noise source in the car itself. The ignition can be the source of radio-frequency (RF) noise with petrol engines, although that is less of a problem these days with plug-on-coil systems that eliminate the spark plug leads. The alternator could also cause noise if the brushes are worn. Have those aspects checked out if the problem persists. Unfortunately, most modern vehicles simply don’t have very good radio reception because consumers don’t want ugly, long aerials sticking out of their cars. Many cars either have a small ‘shark-fin’ antenna like yours or use the rear demister element as an antenna. Neither is all that great of an antenna. If you don’t care about the appearance, you could consider having a flexible whip-style antenna mounted adjacent to the bonnet or on the door frame. Find a good installer who will route the antenna wire neatly and take measures to prevent rusting, or you could mount it yourself if you’re confident. Identifying a Silicon Chip PCB I came across a circuit board recently. I believe that it is a Silicon Chip design and would be grateful if you could tell me what it is used for. The board has the label “SC 11410971 LIGHTS” on it. (G. H., Camden, NSW) ● You can look up PCB numbers on our website at siliconchip.com.au/ Articles/ContentsSearch Simply type the PCB code into the “Kits / PCBs” field and click the “Search” button. Searching for that PCB number gives the following result: October 1997: The Flickering Flame For Stage Work (siliconchip.com.au/ Article/4790) by Ross Tester, kits: Jaycar KC5234, PCBs: SC 11410971, 1 shop item SC siliconchip.com.au