This circuit works like a solid-state contactor. We find it in General Electric documentation from 1965. SCRs can be modern equivalents according to the controlled load.
Using the 2N2646 this circuit was found in a Radio Electronics magazine from July 1968. The...
The purpose of this circuit found in a 1990s Popular Electronics is to increase the current...
Found a documentation for PC from 1992, this circuit is indicated for the English power grid of...