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 oscillator produces a rectangular signal in the range of 100 Hz to 1k Hz but with the change of...
This circuit was obtained in a 1999 English magazine. We can easily assemble it with a BD136 or...
I found this simple circuit from an English magazine from 1984. The circuit can be easily...