This protective circuit for power lines was found in a Radio Electronics from November 1957. The transistor used can be any general-purpose transistor such as the CK722.
This power supply uses a single-winding transformer. We found it in July 1984 Radio Electronics magazine....
This is an old circuit with a unijunction transistor from that time. We found it in a Radio...
Can be used as a shield, this old American documentation circuit offers digitally selected...