Found in a Westinghouse Silicon Power Handbook from the 60s, this circuit makes use of period components. Special high voltage transistors are used. Zeners are 15 V.
Found in a 90s nHands On Electronics, this circuit triggers a relay that shuts off the load when...
Another of the many similar configurations we have in this section. This one is from a Radio...
This circuit for incandescent lamps was found in the January 1980 Radio Elecronics magazine. The...