This symmetrical four voltage source was found in a 1968 Motorola documentation. The circuit is of a type that was commonly used in that time amplifiers.
This relay without lock uses a general-purpose transistor. The relay is according to the supply....
We found this solid-state relay circuit that can function as a shield in a Radio Electronics...
We found this circuit in the April 1993 Electronics Now magazine. Almost any general-purpose JFET...