This 1-transistor circuit for currents up to 50 mA was found in the August 1974 Radio Electronics magazine. The transformer is 50 to 200 mA.
This circuit, which appears at various points in this section and on the website with minor...
Motorola suggests this circuit in an 80's documentation. The circuit uses an inverter to produce a...
This circuit uses a 7812 and another regulator integrated circuit that is not very common...