This circuit was found in documentation from the 1980s. The integrated circuit is from the time and the voltage depends on the desired power, and the component's datasheet should be consulted.
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...