This circuit was found in American documentation from 1966, but it can be assembled with a modern equivalent transistor. The circuit is based on a mechanical tuning fork with a coil feedback system.
This power supply was found in the same 1990 special issue of Radio Electronics Experimenter...
We found this circuit in an old American publication from 1975. It can use almost any common FET...
Found in an Elektor from the 90s, this circuit is based on components that are still common today....