10 kHz Oscillator (CB21830E)

This circuit was found in a 1974 Ferranti transistor manual. The frequency is given by the capacitors, which can be changed.

Simple Relay Shield (CB21223E)
This circuit was found in old American documentation. Transistor is general purpose and relay is...
Simple Alarm (CB25944E)
This simple alarm with latching uses a relay as the main element. The circuit is from a Radio...
Telephone Pickup (CB12308E)
This circuit is from an Italian publication called Fare Elettronica from 1987. What we have is an...