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Contents Vol.29, No.7; July 2016 SILICON CHIP www.siliconchip.com.au Features 16 Directional Drilling: How It Works There used to be predictions that the world would soon run out of oil. That’s not going to happen any time soon and one of the main reasons is directional drilling. It’s not just limited to oil either. Here’s how it works – by Dr David Maddison Universal -33°C to 125°C Temperature Alarm – Page 26. 84 Australian World Record In Photovoltaic Efficiency Australian researchers have achieved a new world record of 34.5% in solar cell efficiency and are now approaching the theoretical limit – by Ross Tester 86 How Good Are Those 2.4GHz AV Senders? AV (audio-video) transmitter-receivers operating at 2.4GHz have been around for a while but their performance is not as good as one might hope. We put a couple of typical units through their paces – by Allan Linton-Smith Pro jects To Build 26 Universal -33°C To 125°C Temperature Alarm This compact alarm can be used to monitor the operating temperature of a wide range of devices. It monitors temperatures in the range of -33°C to +125°C and provides an alarm when the temperature is above, below or outside a userspecified temperature range – by John Clarke Brownout Protector For Induction Motors– Page 34. 34 Brownout Protector For Induction Motors As well as making your lights go dim, brownouts can cause induction motors to burn out due to excessive current draw when they attempt to start. This simple circuit will protect a motor by switching off the power if the voltage falls below a user-set threshold – by Jim Rowe 58 Touchscreen Super Clock This Micromite-based clock is special. It can show the time using either an analog or digital display, track the time in up to 20 different locations (with automatic daylight saving adjustment) and keep precise time using either a lowcost real-time clock (RTC) module or GPS module – by Geoff Graham 76 Stereo LED Audio Level/VU Meter, Pt.2 Our new Stereo Audio Level/VU Meter uses 80 high-brightness SMD LEDs to give a colourful dual-bargraph display. Pt.2 this month gives the full assembly and setting up details and explains how to use it – by Nicholas Vinen Touchscreen Super Clock – Page 58. Special Columns 42 Serviceman’s Log No magic hammers with smart TVs – by Dave Thompson 68 Circuit Notebook (1) Increased Life For Headlights Used As Daytime Running Lights; (2) Two Speedometer Driving Circuits; (3) Precision Resistance Matching Bridge; (4) Turntable Modifications To Lift Tonearm On Power Cut 92 Vintage Radio The Grebe Synchrophase MU-1 5-Valve Radio – by Dr Hugo Holden Departments 2 Publisher’s Letter  98   4 Mailbag 103 25 SC Online Shop 104 siliconchip.com.au 57 Product Showcase 104 Ask Silicon Chip Market Centre Advertising Index Notes & Errata How Good Are Those 2.4GHz AV Senders? – Page 86. July 2016  1