This power supply was found in the same 1990 special issue of Radio Electronics Experimenter magazine that describes an amplifier of up to 100 W per channel with the LM12.
This circuit uses an optocoupler to obtain a solid state relay whose power depends on the Triac...
According to the author of this project, from a documentation on espionage from the 1980s, this...
The first circuit was suggested by Analog Devices (www.analog.com) in its Application Note AN-411...