Found in an American documentation from the 90s, this circuit has a configuration that has been extensively explored in other articles on this site. The FET can be the MPF102 or equivalent.
This control for 12 V drills was found in a 90s Elektor. The components are current, and Q1 can be...
This low power circuit for the FM band was found in a spy book from the 90s. The tunnel diode is...
This double source with current limiter and voltage adjustment was found in documentation from the...