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 is from the 1993 Motorola Linear Interface Circuits. The source does not have to be...
This range is normally used in marine communications as indicated in the 1989 documentation. The...
This shield circuit is from a 1968s Motorola documentation. The relay is according to the supply...