One-transistor oscillator (CB22064E)

Capacitors C2, C3 and C4 determine the frequency of this simple oscillator. Transistor can be general purpose equivalent.

Optical receiver (CB8785E)
Found in a 90’s HAM Radio, this circuit is used for an optical communications system or even audio...
10 to 150 kHz Crystal Oscillator (CB6183E)
This circuit is from a 60's documentation. The capacitance C1 can be between 20 pF and 0.01 uF...
Optocoupler Analog Signal Transmission (CB16935E)
This circuit is from an old French documentation from the 70s. The coupler admits equivalents and...