Newest circuit diagrams

Dark-activated 230V Lamp

Compact circuitry using small-size parts only Can be wired in parallel to existing switches

Q- Multiplying Loop Antenna

This circuit is designed to be used in conjunction with the standard 4 foot square loop used in MW for long distance reception.

Water Activated Alarm

The circuit uses a 555 timer wired as an astable oscillator and powered by the emitter current of the BC109C. Under dry conditions, the transistor will have no bias current and be fully off. As the probes get wet, a small current flows between base and emitter and the transistor switches on. A larger current flows in the collector circuit enabling the 555 osillator to sound.

Single Zone CMOS Alarm

This circuit features automatic Exit/Entry delays, timed Bell Cut-off and System Reset. It has provision for normally open and normally closed switches and will accommodate the usual input devices such as Foil Tape, Pressure Mats, Magnetic Reed Contacts, Passive Infrared Detectors and Inertia (Shock) Sensors.

IR Remote Control Extender Mark 2

This is an improved IR remote control extender circuit. It has high noise immunity, is resistant to ambient and reflected light and has an increased range from remote control to the extender circuit of about 7 meters. It should work with any domestic apparatus that use 36-38kHz for the IR carrier frequency.

2 Transistor FM Transmitter

This circuit may be tuned to operate over the range 87-108MHz with a range of 20 or 30 metres.

Miniature Loop Alarm

A few months ago, I decided to build a compact, yet effective alarm. My demands were:- simple construction, reliable operation, very small power consumption, and, most of all, small size. I started with CMOS logic gates, but was soon forced to abandon the concept after a few unsuccessful (and far too complicated) attempts. Then I suddenly realized that a simple transistor switch might do the job and I was right.

Motorcycle Alarm

Any number of normally open switches may be used. Fit the mercury switches so that they close when the steering is moved or when the bike is lifted off its side-stand or pushed forward off its centre-stand.

Sound Effects Generator

This circuit uses a UM3561 IC to produce four different sound effects.

Overvoltage Protection for the LM317

This is an add-on Over Voltage Circuit for the LM317 Regulator Circuit submitted by Matthew Hewson.