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Contents Vol.22, No.7; July 2009 www.siliconchip.com.au SILICON CHIP Features 12 The Magic Of Water Desalination The driest continent on Earth is about to get much more drinking water from the sea, thanks to new desalination plants. Here’s a look at how they work – by Geoff Graham The Magic Of Water Desalination – Page 12. 20 Review: Two Low-Cost DVD Recorders Thinking of retiring that ancient VCR and getting a DVD recorder? Here’s a look at two low-cost units: the Tevion DD1018 & the AWA DR711 – by Barrie Smith Lead-Acid Battery Zapper & Desulphator Mk.3 – Page 26. 78 CeBIT: What’s New At Australia’s Largest IT Show? There’s lots to see at CeBIT. We took a stroll around the displays to bring you this report – by Ross Tester Pro jects To Build 26 Lead-Acid Battery Zapper & Desulphator Mk.3 Rejuvenate old lead-acid batteries by zapping them with high-voltage pulses to dissolve the lead-sulphate crystals on their plates. It works with 6V, 12V & 24V batteries & is easy to build – by Jim Rowe 38 Hand-Held Metal Locator Compact unit is ideal for finding steel frames & studs, steel bracing & nails in plaster walls. And it can discriminate between ferrous and non-ferrous metals – by John Clarke 58 Multi-Function Active Filter Module Versatile design is ideal for use as an active crossover in loudspeaker systems but has other uses as well. It can be configured as a low-pass filter, as a highpass filter or as a bandpass filter using on-board jumpers – by John Clarke 80 High-Current, High-Voltage Battery Capacity Meter, Pt.2 Hand-Held Metal Locator – Page 38 This month, we guide you through the once-only setup and calibration procedure. We also tell you how to use it – by Mauro Grassi Special Columns 70 Circuit Notebook (1) RF Preamplifier For World-Band Receivers; (2) Signal Inverter Runs From 5V Rail; (3) Simple Water Spillage Alarm; (4) Accurate Timer Locked To 50Hz Mains Supply; (5) Enhanced Software For The Appliance Energy Meter 44 Serviceman’s Log Car electronics: a whole new ballgame – by the Serviceman 89 Vintage Radio The Lyric 8-Valve Console From The 1920s – by Rodney Champness Departments   2   4 19 37 Publisher’s Letter Mailbag Subscriptions Order Form siliconchip.com.au 57 96 99 102 Product Showcase Ask Silicon Chip Notes & Errata Market Centre Multi-Function Active Filter Module – Page 58. July 2009  1