This circuit was obtained from a Radio Electronics in February 1965. The circuit uses two transistors from the time and can be created with modern equivalent transistors.
Found in a Hands On Electronics from the 80's, this circuit activates a relay with alternating...
The frequency of this circuit, that makes use of a tunnel diode as an active element, depends on...
Found in 1980s Electronic Engineering, this circuit uses common phototransistors as sensors. The...