Found in a 1969 Ferranti documentation, this circuit uses only bipolar transistors from that time. Transistors can be replaced with modern 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...