6 V power supply with power zener (CB21531E)

This circuit provides 6.3V of output from a 9V input. The circuit was found in a Dutch publication from 1966.

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...