This circuit was found in documentation from the 1980s. It is powered by the audio signal that must be cut. Transformers are the critical components and transistors are 2N2222.
This circuit is from a Linear Technology integrated circuit manual from the 1990s. The circuit...
This basic configuration of voltage regulator using operational amplifier and zener was found in a...
This Colpitts crystal oscillator was found in an American publication for amateurs in the 1980s....