An automatic control for various domestic appliances has a ferrite core which surrounds the run winding for the drive motor of the appliance. The run winding represents the primary winding for the ferrite core, which has a secondary winding at which a brief output voltage is generated whenever the run...http://www.google.com.au/patents/US4481786?utm_source=gb-gplus-sharePatent US4481786 - Electronic control for a domestic appliance
