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.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...