This 4-voltage power supply using zener diodes has a maximum recommended current of 25 mA. The circuit was found in the May 1966 Radio Electronics magazine.
This basic configuration can be found in a lot of articles on this site. In this case, the relay...
This circuit is from American documentation from the 1980s. The transistors are general purpose...
The circuit is simple, as it uses only one transistor and a relay that can be MC2RC1 or MC2RC2,...