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Coming up in Silicon Chip Anodising aluminium Professionally-made aluminium pieces are often anodised, for protection against damage and corrosion, or to change their colour. Sometimes you don’t have that option, though, especially when you are making aluminium panels at home. But the anodising process is not that complicated and you can do it at home with just a few basic tools and chemicals. We’ll explain how. DIY solder reflow oven with PID temperature control Advertising Index Altronics...............................85-88 Ampec Technologies............... 106 Arduino Day at maker hub......... 37 Blamey Saunders hears.............. 9 We’ve previously described how you can use a toaster oven to reflow solder paste. This is a great way to solder many SMDs at once, but it’s a bit “hit and miss”. By adding this PID temperature controller, you can get the oven to follow the correct soldering temperature profile, and get good results every time! It’s also great for curing glues and paints at lower temperatures. Dave Thompson...................... 111 Mono & stereo 7-band equalisers Hare & Forbes..........................2-3 These two equalisers use rotary pots, so they can easily be installed in preexisting equipment like amplifiers or preamplifiers. They are simple to build and have stellar performance. They’re ideal for compensating for uneven loudspeaker or room responses, or just tweaking the sound profile to your liking. Jaycar............................ IFC,53-60 Stealth Technology Digi-Key Electronics.................... 5 Emona Instruments................. IBC Keith Rippon Kit Assembly...... 111 LD Electronics......................... 111 Making giant metallic objects like aircraft or ships vanish from radar (and other sensors) may seem like witchcraft, but it’s actually a feat of science and engineering. The full details are naturally kept secret, but in this article, Dr David Maddison presents what is known about the various technologies used to absorb and deflect radar signals. We also describe other ‘low observable’ techniques to reduce the visible, infrared and audible signals of various vehicles and even people. LEACH PCB Assembly............... 7 Note: these features are planned or are in preparation and should appear within the next few issues of Silicon Chip. Pakronics................................... 21 The April 2020 issue is due on sale in newsagents by Thursday, March 26th. Expect postal delivery of subscription copies in Australia between March 24th and April 10th. RayMing PCB & Assembly........ 12 Notes & Errata AM/FM/CW Scanning HF/VHF RF Signal Generator, June & July 2019: some constructors have described erratic operation of the rotary encoder. The designer has tracked this down to variations in the internal RC oscillator frequency of the ATmega328P microcontroller (IC1). Revised software (V11) is available for download from the Silicon Chip website which fixes this. This new version will also be used to program any chips ordered from now on. Battery booster wanted I am putting a second battery in my vehicle to keep my fridge running when the engine is stopped. I am going to use a 36Ah sealed lead-acid (SLA) battery, also known as a gel cell. I have the necessary dual battery switching, but this will only charge the SLA to the flooded battery voltage, where the SLA full charge voltage is specified as 14.4-15V. Have you ever described anything 112 Silicon Chip that will boost the car’s output voltage up so that it will charge the SLA correctly? (P. C., Balgal Beach, Qld) • We spent some time working on such a design about ten years ago, but found that the parts to build a decently powerful ‘caravan booster’ cost more than a commercial off-theshelf unit. Hence, we have never published such a design. However, you may like to look at our July 2019 article on building a Dual Battery Isolator Australia’s electronics magazine LEDsales................................. 111 Microchip Technology................ 11 Ocean Controls......................... 13 Rohde & Schwarz.................. OBC Silicon Chip PDFs.................... 95 Silicon Chip Shop.................... 89 The Loudspeaker Kit.com........... 8 Vintage Radio Repairs............ 111 Wagner Electronics................... 71 (siliconchip.com.au/Article/11699) as it is related to your situation. While it would be better to charge the SLA battery according to specifications, it should charge sufficiently at the flooded battery charge voltage to provide for running the fridge. Just make sure to minimise losses between the vehicle’s alternator regulator output and the secondary battery, eg, use thick cables etc. Any loss along the way will only lead to a lower final charge on the added battery. SC siliconchip.com.au