17 November 2008

15 November 2008

This handy circuit can be used as a speed controller for a 12V motor rated up to 5A (continuous) or as a dimmer for a 12V halogen or standard incandescent lamp rated up to 50W. It varies the power to the load (motor or lamp) using pulse width modulation (PWM) at a pulse frequency of around 220Hz.

13 November 2008

Ever wanted to be an air traffic controller? This will let you experience it all - from the comfort of your PC!

29 October 2008

27 October 2008

This LCD USB Clock connects to your PC's USB port. It synchronises its time with your PC - and ultimately an internet time server - when your PC is on to maintain accurate time-keeping. It can also operate on its own using battery back-up and has user-selectable display modes.

25 October 2008

I decided to build the UV exposure box for photo-sensitive PC boards, as published in the November 2007 SILICON CHIP. The first thought I had was to use the timer module in an old microwave oven, instead of building the timer design used in the project. Then I thought: "Why not use the whole oven?"

23 October 2008

This automatic timer has a wide range of applications whereby a timing cycle is initiated in response to a trigger signal. There are quite a few uses for it in a car or you could use it on a model railway layout, in a home security system or whatever.

19 October 2008

Interesting circuit ideas which we have checked but not built and tested. Contributions from readers are welcome and will be paid for at standard rates.

17 October 2008

Need to measure small signals at radio frequencies? Here is a low-cost digital level and power meter which will allow you to measure RF signals from below 50kHz to above 500MHz. As well as indicating the signal level in volts and dBV, it also shows the corresponding power level (into 50 ohms) in both milliwatts and dBm.

15 October 2008

Telemetry (from the Greek tele = remote and metron = measure) refers to the remote measurement and reporting of information, typically using wireless links to carry the data. Such technology is well established in climatic monitoring (especially temperature), water management, motor sport, security, medicine, defence and even space - Martian probe style.