February 2009 Issue

A summary of this month's contents.

LED Tachometer (Part 1)

This combined analogue/ digital rev counter is suitable for most 2-stroke and 4-stroke engines. It features a fast response 32-led circular bargraph display together with a 4 digit seven segment readout. The bargraph responds rapidly to changes in the engine's r.p.m. allowing you to monitor trends effectively, whilst the digital display shows accurate revs with a steady throttle. PIC microcontroller based, with free source code available from our Library. Gear shift indicator l.e.d. and selectable 'red line'. In Part One we describe the circuit principles and assembly with setting up provided next month.

 

Adjustable Regulated Power Supply

A simple design offering a fully regulated voltage ranging from 1.2 to 22V at currents up to 1A. An excellent introduction to using three terminal variable regulators.

 

20W Class-A Amplifier Module (Part 5)

In this final article we show you how to build a high-performance 20W stereo amplifier using the modules described over the last few months. In the Oct. 08 and Nov. 08 issues we published the circuit and assembly details for our new high performance 20W Class-A stereo power amplifier modules and power supply. The Dec. 08 issue carried the Speaker Protection and Muting Module and we followed up last month with a Low-Noise Pre-amp and Remote Volume Control module.

 

This month we show how everything is brought together into a custom-designed steel chassis to create an audio system that you can be really proud of. Full interwiring details and photographs are included to enable experienced constructors to assemble this system confidently.

 

Breadboarding Projects

Our simple solder-free projects are specially designed to enable beginners to experiment with safe, low-cost circuits. Part Five offers a neat Frost Alert, which sounds an audio alarm when the air temperature reaches the freezing point of water. A Simple Dice provides a random reading on a row of six leds.

 

Also in the February 2009 issue:

 

  • TechnoTalk - how an experiment using a camera chip to replace a damaged eyeball could have far more applications than the designer intended, and the future looks bright for analogue semiconductors.
  • Recycle It - making something useful out of scrap parts: how to transform an old VU meter into a voltmeter, and our expert salvager browses over some interesting-looking old thermostats.
  • Interface - our PC interfacing feature offers more on serial port compatibility.
  • Circuit Surgery - our in-house 'surgeon' lifts the lid on MOSFET physics and paralleled transistors.
  • PIC n MIX -our popular column dedicated to the PICmicro continues with techniques for interfacing PICs to the Internet via Ethernet.
  • Net Work - the internet column walks through some current trends in mobile Email, suggestion an effective filtering service to help you use mobile email free from spam.

 

 

Source code 0209.zip

PCB files pcb0209.zip

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