Found in a Popular Electronics from the 90s, this circuit activates a recorder for automatic recording of telephone calls. The circuit was used with old cassette recorders of the time.
With this name, we find in a documentation by Hugo Gernsback from 1960 this small transmitter for...
This simple receiver, which requires a good antenna and grounding, was found in an Argentine...
This sinusoidal oscillator was found in Radio Electronics in 1989. It uses a 741, but other...