This circuit was found in a 90s EDN. Its purpose is to increase the efficiency of operational amplifiers. Power MOSFETs and inverted zeners support equivalents.
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...