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.
The output power of this wireless intercom for the 27 MHz (11 meters) range is in the order of ½ W,...
In the figure we have the way to implement an Exclusive OR or XOR gate with CMOS or TTL...
This useful circuit is used to test the insulation of cables, appliances, leaks in high voltage...