Newest circuit diagrams

Capacitive Sensor

Special design for shop-windows animation. Useful for many types of touch controls

Antenna Tuning Unit

A simple passive (no power required) circuit to match an antenna to a radio receiver. This will be a useful addition to the short wave listener, but in addition a medium wave coil is almost used to tune the medium wave band.

Small Variable power Supply

Features: 1.3-12.2 V, 1 A, over-current protection. This is a simple but reliable device based one of the oldest integrated voltage regulators of them all - the LM723.

Switch De-Bouncer

This circuit will remove the transient spikes and contact bounces from a non-latching push button switch.

Latch Switch 2

This circuit uses a Silcon Controlled Rectifier (SCR) as a latch switch. Once enabled it can only be turned off by pressing S2 or power is removed from the circuit.

Speaker Mic Circuit

This circuit takes an ordinary loudspeaker and allows it to be used in reverse, as a microphone.

Courtesy Light

15 seconds delayed switch-off. A good idea for bedroom lamps

Basic UPS

This circuit is a simple form of the commercial UPS, the circuit provides a constant regulated 5 Volt output and an unregulated 12 Volt supply. In the event of electrical supply line failure the battery takes over, with no spikes on the regulated supply.

12 Volt 20 Amp Power Supply

A 12 Volt high current 20 Amp power supply. The output voltage is variable from 12.2 Volt to 14.4V so can be set for any device requiring voltage and current in that range. This PSU uses an LM723 as the regulator, 4 parallel connected outboard pass transistors and has current limiting above 25 amps.

Simple Motorcycle Alarm

This is a simple - easy to build - transistor based motorcycle alarm. It's designed to work at 12-volts. But - if you change the relay for one with a 6-volt coil - it'll protect your "Classic Bike". The standby current is virtually zero - so it won't drain your battery.