This dual-tuned 60 Hz oscillator was found in the Radio Experimenter Special projects of 1993. The circuit has the timing ranges given by C1 which can be changed.
This is one of the possible configurations using the LM139, 239 or 339 voltage comparators. The...
Found in a 303 Circuits from the 90s, this circuit converts signals from the 10 kHz to 150 kHz...
This circuit is from a Radio Electronics issue of May 1972. It consists of a commercial heating...