April 2009 Issue
A summary of this month's contents.
Super Accurate GPS-Based Frequency Reference
This very high quality design uses a PIC 16F628A microcontroller to create a highly
stable frequency reference that is linked to the Global Positioning System (GPS)
satellite network. It utilises their highly accurate on-board caesium-beam 'atomic
clocks' in conjunction with a Garmin GPS module to generate a clock signal. An
onboard temperature-stabilised 'oven' uses a transistor as a heater to ensure stability. Our GPS-based Frequency Reference drives a continuously updated LCD showing
UTC time and date, GPS fix and PLL status. 
You can also read a short-term display of
various navigational co-ordinates and basic satellite signal strength quality. An
incredible project for skilled constructors to get their teeth into! Free source code is
available from our Library.
Oscar Noughts & Crosses Machine
Noughts and Crosses (or Tic Tac Toe) is an old favourite and this article retraces the
steps of the first electronic simulators capable of proving a worthy match for a human
opponent. Our PIC-powered version brings the game up to date, using a keypad and
bicolour led's in place of the mechanical switches and valves (vacuum tubes) of its
predecessors. Free source code available from our Library.
Versatile Four Input Mixer
This low-cost, low-noise design is suitable for a wide range of signal sources. Its pre- amps can be configured to match a wide range of signals including mic, guitar, tape, synth or CD. It has a built-in equaliser with bass, midrange and treble controls, plus a monitor amp for headphones. Full specifications and assembly details are included in the article.
Breadboarding Projects (Part 7)
This series was specially written for beginners in electronics who are taking their first steps in project experimentation. Using a solderless 'breadboard' you can plug components together without the need to solder: remove or modify them and re-use them! This month we describe an ultrasonic remote control system that allows the on- off operation of low power circuits.
Also in the April 2009 issue:
- Techno Talk on the latest intriguing developments in LED technology that hopefully will finally make low-cost low-energy lighting a reality.
- PIC n MIX – starting a new mini series on getting video from a PIC microcontroller, in a format suitable for driving many of the popular TV standards with appropriate user modifications.
- Recycle It – making a vibration detector from a cassette deck and a pair of loudspeakers. A great example of 'lateral thinking' .
- Interface – the PC Column describes how to use handshake outputs as power sources capable of some low power applications.
- Net Work – the Internet column – some considerations for managing with a mobile service when your broadband line goes down.
