Low Voltage Test (CB22158E)

This is a simple voltage tester for voltages from about 2V to about 15V with the indicated resistor and red LEDs.

Delayed light (CB10091E)
This circuit for incandescent lamps was found in a 70s documentation. The circuit uses an SCR...
Ultra-simple FM or shortwave radio (CB23973E)
This circuit is from an Elementary Electronics from 1977. It can be assembled with relative ease...
Transmitter Detector (CB26100E)
This circuit detects the presence of strong signals from spy transmitters, enabling their...