Found in a 1967 American publication, this circuit with feedback for two transistors has a gain of 20 times. Phototransistors are types of the time.
This circuit for conventional lines was obtained in a 1996 documentation. The circuit uses common...
This tube circuit was found in the magazine 73 for radio amateurs in an issue from the 1980s. Note...
September 2016 - can already be found at Mouser Electronics new integrated circuit from Texas...