This circuit was found in American documentation from the 90's. The transformer determines the output voltage. The transistor must be equipped with a heat sink.
This circuit for frequencies up to a few tens of megahertz was found in the April 1978 issue of...
This is another possible version of a negative voltage generator using a 555 integrated circuit. The...
This Dimmer circuit for incandescent lamps was found in an English documentation. The input...