Newest circuit diagrams

4 Transistor Transmitter

This circuit provides an FM modulated signal with an output power of around 500mW.

Buffer Amplifier

hifi preamplifier designed to convert high output impedance amplifiers to 600 ohm outputs.

Current Limiting Power Supply

This is a 1-amp variable-voltage PSU. It adjusts from about 3v to 24v: and has the added feature that you can limit the maximum output current. This is invaluable when (for example) you power-up a project for the first time or soak-test a piece of equipment.

Parking Light Switch

This is a simple parking light switch. The idea is that you drive your car towards your garage. You shine your headlights at the sensor, which switches on an external light . If you don't have a garage the sensor can be placed on a wall or post, and the external light will illuminate the area while you park and leave your vehicle. The circuit also has manual on and off controls.

Bicycle back Safety Light

Flashing 13 LED unit, 3V supply. Also suitable for jogger/walkers

NE555 Monostable

Use of the ubiquitous 555 timer in monostable mode.

Two-Zone Intruder 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.

Flashing-LED Battery-status Indicator

Signals when an on-circuit battery is exhausted. 5V to 12V operating voltage.

Infra Red Link

A basic Infra Red Link for audio communication for distances upto 3 metres.

Battery Status Indicator

There are many circuits available on the net, for indicating battery status.