This power supply uses a Raystor which is a 1964 LDR lamp coupler. The circuit was found in an Electronic Design and the transistor can be replaced with the current equivalent.
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...