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Contents Vol.23, No.9; September 2010 SILICON CHIP www.siliconchip.com.au Features 14 Review: Fusion 600 Marine A/V Series New Zealand-designed Fusion Audio equipment for boats is making real waves around the world – by Kevin Poulter LED Replacement Tubes For Fluorescent Lamps – Page 16. 16. 16 LED Replacements For Fluorescent Lamps Fluorescent tubes are now being challenged by LED tubes which use half the power, last twice as long and put out lots of light – by Leo Simpson 22 Designing & Installing A Hearing Loop For The Deaf, Pt.1 Many people have a hearing impairment and hearing loops which inductively couple an audio signal to a hearing aid are now common. Here’s how to design and install one – by John Clarke 67 Charlieplexing: What It Is & How It works This multiplexing technique can really cut down on the number of outputs required to drive a LED d isplay – by Nicholas Vinen Pro jects To Build 34 Ultrasonic Anti-Fouling Unit For Boats, Pt.1 Marine growth on the hull is the bane of all boat owners. Keep the barnacles at bay electronically with this high-power ultrasonic unit – by John Clarke Ultrasonic Anti-Fouling Unit For Boats – Page 34. 42 High-Performance Microphone Preamplifier This compact module accepts either a balanced or unbalanced microphone input and provides a line-level output with very low noise and distortion. It runs off 5-20V DC and consumes just 6mA – by Nicholas Vinen 62 Build A Hearing Loop Receiver This low-cost unit picks up hearing loop signals and drives a pair of headphones. It works with commercial loops in public places or you can use it with a loop that you install in your own home – by John Clarke 70 Electrolytic Capacitor Reformer & Tester, Pt.2 Second article shows you how to put it together and install it in a plastic case – by Jim Rowe High-Performance Microphone Preamplifier – Page 42. Special Columns 57 Serviceman’s Log Electros with lumpy bits are not good – by the Serviceman 84 Vintage Radio All about thermionic valves (or vacuum tubes) – by Maurie Findlay Build A Hearing Loop Receiver – Page 62. 90 Circuit Notebook (1) PICAXE Refrigerator Timer For Cafes; (2) PICAXE I/O Demonstrator Circuit; (3) Magnetic Pole & Flux Strength Indicator; (4) Automatic Exterior Light; (5) 6-Stage Cascaded Timer Uses SCRs Departments   2   4 41 95 Publisher’s Letter Mailbag Product Showcase Ask Silicon Chip siliconchip.com.au 98 Notes & Errata 99 Order Form 102 Market Centre September 2010  1