This countdown electromagnetic ring launcher was found in an Electronic Hobbyst Handbook from 1993. The components can be difficult to obtain. Details of the launch coil were not given.
This simple 3-transistor circuit for short-range headphone listening was found in a Radio...
This circuit uses a transistor to trigger the alarm from a low quiescent current sensor. The relay...
This receiver using a FET appeared in a November 1957 Radio Electronics magazine. It is one of the...