Newest circuit diagrams

Logic Probe

This logic probe uses a single CMOS 4001 IC and can display high, low and pulsing outputs.

2 Transistor Transmitter

A compact 2 transistor transmitter for use at VHF frequencies.

Fading LEDs

Two strips of LEDs fading in a complementary manner. 9V Battery-operated portable unit

Constant Motor Speed Control

A simple op-amp feedback circuit designed to regulate the speed of a DC motor.

Gyrator Circuit

An electronic recitification circuit. The use of large, heavy and expensive electrolytic capacitors is avoided, being replaced by an active transistor in this gyrator circuit.

5 Digit Alarm Keypad

This switch will suit the Modular Burglar Alarm circuit. However, it also has other applications. The Keypad must be the kind with a common terminal and a separate connection for each key.

Power Outage Warning

5 to 15V supply - LED indicator. Adjustable time detection

Room Monitor

This circuit allows audio monitoring of a remote location and so doubles as a room monitor or baby alarm.

Live-line Detector

Detects the presence of a live mains conductor Minimum parts counting

Broken Charger-connection Alert

Detects if a device is not properly connected to its supply Suitable for battery chargers, portable appliance supplies etc.