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Contents Vol.32, No.8    August 2019 SILICON CHIP www.siliconchip.com.au Features & Reviews 14 Fluid logic, Fluidics and Microfluidics Computers and ‘circuits’ based on fluid flows have been built and used since the late 1950s – now microfluidics brings even more options – by Dr David Maddison 27 We visit the new “maker hub” concept by Jaycar It’s unlike any Jaycar store you’ve ever seen. Imagine being able to produce your own projects using the latest equipment – in the store! – by Tim Blythman 42 Canberra’s Vintage Radio “MegaFest” Organised by the Historical Radio Society of Australia, the largest display, market and workshop comes to the national capital in September – by Richard Begbie 68 First look: the new Raspberry Pi 4B The Pi has been called the “gold standard” in single board computers – now the 4B (with some delicious new features) is becoming available – by Tim Blythman 78 Quantum-dot Cellular Automata While still mostly theoretical, QCA chips could potentially operate at THz speeds and with even higher density than the latest CMOS processes – by Sankit R Kassa Constructional Projects 30 Micromite LCD BackPack Version 3 The most convenient and powerful BackPack yet. It has all the features of the V1 and V2 BackPacks and supports both 2.8in and 3.5in touchscreen displays plus five new optional features – by Tim Blythman 48 “HEY! THE SIGN SAYS NO JUNK MAIL!” Is your mailbox constantly chock-a-block full of junk mail, even with a “no junk mail” sign? This cheap and simple project tells junk mail purveyors – literally – to cease and desist (or any other message you want to record!) – by Allan Linton-Smith 70 Radio Head Unit Dimmer Adaptor Very few aftermarket car radio ‘head units’ offer a dimming function. This simple project adjusts the display and backlighting brightness as you dim your instrument lights. It can also be used as a simple vehicle voltage interceptor – by John Clarke 84 Discrete Logic Random Number Generator By combining just a few logic ICs, it is possible to digitally generate a pseudorandom number sequence: very handy if you need some random number generation (and it will help you understand logic ICs!) – by Tim Blythman Your Favourite Columns 62 Serviceman’s Log Remaking a “vintage” guitar FX pedal – by Dave Thompson 90 Circuit Notebook (1) PICAXE “Knightrider” LED chaser display (2) Voice modulator for sound effects (3) Arduino LoRa chat terminal with QWERTY keyboard (4) Phantom-powered microphone over telephone cable (5) AM radio distribution amp 96 Vintage Radio: 1924 RCA AR-812 Superhet The world’s first commercially available superhet – by Dennis Jackson Everything Else! 2 Editorial Viewpoint 4 Mailbag – Your Feedback siliconchip.com.au 61 Product Showcase 104 SILICON CHIP ONLINE SHOP 106 111 112 112 Ask SILICON CHIP Market Centre Advertising Index Notes and Errata There’s renewed interest in the notwell-understood field of fluidics and microfluidics, with some exciting possibilities ahead – Page 14 We made a quick visit to Jaycar’s new concept “maker hub” – and we came away very impressed! – Page 27 The new Micromite BackPack V3 now supports 3.5-inch screens and has many more cool features but costs very little more than its predecessors – Page 30 Imagine their shock when they shove yet another junk mail flyer in your letterbox – and a hidden voice tells them to go away! – Page 48 It’s only been a year since the last Raspberry Pi was released. . . and now there is a brand new one. Here’s our first look at the Pi 4B – Page 68 Does your new radio Head Unit blind you at night? Here’s how to cure it! – Page 70 www.facebook.com/siliconchipmagazine