This circuit was found in an English publication from 1967. The circuit is for listening on a phone. Transistors are types of germanium of the time.
This circuit produces a square wave signal with the frequency determinated by R1 and C1. The upper limit...
) This variable frequency oscillator was found in an old American documentation. Transistors allow more...
The frequency of this type is oscillator is given by the RC network. Calculations can be found in...