Voice Scrambler (CB22462E)

We found this circuit in a Popular Electronics from 1992. It consists of a voice scrambler used in telephone transmissions.

Variable Oscillator (CB23970E)
This 1-transistor Hartley oscillator generates an audio signal that is dependent on capacitor C1....
Perforated Tape Reader (CB16920E)
We found this circuit in an old French documentation from the 70s, but it can be assembled using...
Miller Oscillator (CB5121E)
This crystal-controlled oscillator was obtained from an American 1980s documentation. The circuit...