This sophisticated repellent uses a double 555. We find it in an American documentation from the 80's. The circuit can be powered by batteries or source included in the diagram.
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...