This circuit is from the Motorola Linear Databook of 1990. The coils must be according to the frequency of the signal.
This is one of the many hysteresis comparator circuits the reader may find in this section and on this...
This circuit is from a Radio Electronics from February 1971. The SCR is load controlled and the...
Found a documentation on PCs from 1996, this circuit can be used as a shield. The relay is rated at...