Newest circuit diagrams

Digital Step-Km Counter

Max. range: 9,950 meters with two digits. Slip it in pants' pocket for walking and jogging

SW Aerial Amplifier

A radio frequency amplifier to boost SW reception. Frequency range approximately 5 to 20 MHz.

Security Monitor

A remote listening circuit. The area to be monitored is connected via a cable and allows remote audio listening.

Infra Red Extender

This circuit was sent to me by Mr Guy Bocquillon from France. Now retired, and in his seventies, Mr Bocquillon keeps himself active in his hobby and his results and support are most appreciated.

Modular Burglar Alarm

This circuit features automatic Exit and Entry delays and a timed Bell Cut-off. It has provision for both normally-closed and normally-open contacts, and a 24-hour Personal Attack/Tamper zone.

Two-Zone Burglar Alarm

This is a two-zone alarm - with automatic exit, entry and siren cut-off timers. It can be triggered by the usual types of normally-closed input devices - such as magnetic reed contacts - foil tape - PIRs etc. I've used a 12-volt supply in the diagram - but the circuit will work at anything from 9 to 15-volts. All you need do is select a siren, buzzer and relay to suit the voltage you want to use.

Electronic Siren

An electronic siren made from discrete components. A push button switch is used to create the sound, which rises in pitch when the switch is pressed, and falls in pitch when the switch is released.

Automatic Repeater

It is a self powered (audio derived) repeater circuit for receiving a signal and re-transmitting it via the other radio.

30 Watt VHF Amplifier

The 30 watt amplifier schematic shown below provides an appropriate power boost with an input of 4 watt up to 6 watts. The circuit is designed to cover 88-108MHz FM Broadcast Band.

Nicad Battery Charger

A basic nicad battery charger using a single medium power transistor.