This power supply was found in a RCA publication from the 1970s. The circuit uses transistors from that time. Modern equivalent transistors can be used.
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...