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.
This circuit simulates an inductor. Or operational amplifier of old type, but a configuration is...
This circuit for the logic control of the 555 in a power supply was found in the October 1989...
This traditional configuration from a 1980 publication shows how a reed relay is used to control a 240...