A self-redulanting heater includes an electrically-conductive substrate (11), having a magnetic surface layer (13) of one skin depth, folded 180 degrees to define two heater sections joined by a fold section. The magnetic material has a considerably higher resistance than the substrate material. The...http://www.google.com/patents/US4990736?utm_source=gb-gplus-sharePatent US4990736 - Generating electromagnetic fields in a self regulating temperature heater by positioning of a current return bus
