This circuit from a Radio Electronics from October 1965 shows how to obtain the action of an SCR when triggering a relay using two transistors. The relay is according to the circuit supply voltage.
This sophisticated alarm with traditional components was found in an ancient American...
This circuit is from a Fairchild digital clock module shown in the March 1977 issue of Radio...
This circuit was obtained in a Radio Shack documentation from 1977. It can be used as a multimedia...