We find this circuit in American documentation from the 1980s. It consists of a frequency folder using a varicap. The capacitors and coils depend on the frequency of operation.
This circuit was discovered in an English publication in 1979. The circuit can still be assembled with...
With this circuit it is possible to obtain a voltage of -5 V from a 5 V source. The circuit is...
This simple experimental circuit using only transistor produces a tone given by C1 and C2. Tone is...