Apparatus to control the cooking temperature of foods

An apparatus to control the cooking temperature of foods, comprising;

• a thermistor for sensing the temperature of the food, said thermistor in intimate contact with said food, an electromagnet, a first set of wire spires coiled over the electromagnet's iron core, a second set of wire spires coiled over the electromagnet's iron core, with said first and second sets of wire spires coiled in opposite sense, an iron armature, a first electrical circuit consisting of an electrical power source connected in series to said first set of spires and switching means, whereupon operation of said switching means causes current to flow in said first circuit, said current flow being substantially constant, thereby generating a substantially constant magnetic flux through the core and the armature, said magnetic flux causing attractive magnetic forces between the core and the armature, springs applied to said armature and exerting forces partially opposed to said attractive magnetic forces, a second electrical circuit consisting of said thermistor connected, in series, to said second set of spires, a power source and a rheostat, said thermistor having a negative coefficient of resistance, its resistance decreasing when the food temperature increases, whereupon the current flowing through said second circuit increases, causing an increasing magnetic flux through the core and armature, said increasing magnetic flux being in the opposite direction to said constant magnetic flux in said first circuit, thereby decreasing the attractive magnetic force on the armature and causing its separation from the core when said force, for a desired control temperature of the food, becomes smaller than the opposing force exerted by said springs, a third electrical circuit comprising, in series, a power source, alarm means and a switch cooperating with the armature, said switch becoming operative upon separation of the armature from the core, whereupon said third circuit is energized and the alarm means are activated, said alarm means being activated for differing food control temperatures by operating on the variable resistance of said rheostat.