Found in a 90’s HAM Radio, this circuit is used for an optical communications system or even audio transmission by optical fiber. The components are common.
This circuit is temperature stabilized. Modern equivalent transistors can be used, and the power...
This circuit uses an optocoupler to obtain a solid state relay whose power depends on the Triac...
This power step for relay activation was found in the 1964 RCA transistors manual. The circuit is of the...