This symmetric 30 mA x 15 V power supply was found in the Ferranti transistor manual from 1974. Transistors are common types at the time.
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....