Found in a PE Hobbyst Handbook of 1991, this circuit was originally proposed to time photographic baths in developing rooms but can be used for other purposes. The circuit beeps at 30-second intervals.
This is the typical audio amplifier for a 1967 television. We found it in a magazine from the...
This alarm is designed for doors and windows, but nothing prevents it from being used in cars,...
With a unijunction transistor and a tunnel diode it is possible to obtain rise times of 1 ns with...