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March 2009 Issue

A summary of this month's contents.

LED Tachometer (Part 2)

This combined analogue/ digital rev counter suits most 2-stroke and 4-stroke engines. It features a digital display plus a fast-response 32-led circular bargraph which 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.

In Part Two the constructional details are provided, plus testing and setting up methods.


Digital Stereo VU/ Peak Meter

This easy-to-build PICmicro-powered LCD bargraph VU meter makes the recording of stereo audio at correct levels a cinch. It shows both the average signal and peak levels in stereo on an LCD, and you can program both the display range and number of steps (blocks). A digital display option is also available. PIC 16F88-powered, with free source code available from our Library.


Tank Water Level Indicator

Keep a check on the level in a water tank or rainwater barrel using this simple integrated design. Our straightforward 10-stage LED bargraph plus a 'Critical' flashing LED is all you need to keep an electronic eye on your tank's contents. Powered by a commonly available mains adaptor.


Also in the March 2009 issue:


Breadboarding Projects (Part 6) - Bat Detector



A simple circuit that detects the ultrasonic squeeks of bats and converts them into a human-recognisable audio form. Build on solderless breadboard.


  • TechnoTalk - exploring the world of femto technology and femtocells, or low power wireless access points.
  • Recycle It - making something useful out of a scrap washing machine level switch
  • Practically Speaking - our practical workshop series offers useful advice to help constructors identify the markings of common semiconductor components.
  • Circuit Surgery - how to interface audio equipment together and match their impedances
  • PIC n MIX - our popular column dedicated to the PICmicro continues with Part 6 of the special feature covering techniques for interfacing PICs to the Internet via Ethernet.
  • Net Work - the Internet column on sending SMS text messages via the Internet, and more on mobile Internet usage.


Source code

PCB files

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