Obtained in an Electronic Design from 1968, this circuit has the voltages determined by the zener diodes. Transistors can be modern equivalents.
This circuit is from 2001 documentation, serving to multiplex stereo signals for FM transmitters. The...
This circuit reverses the signal if both positive and negative. We found it in an American...
Found in a publication by Gernsback from 1960, this circuit makes use of germanium transistors of the time....