Abstract: A controllable heating pad, having a heating conductor embedded in the heating pad, a sensing conductor embedded in the heating pad, a resistive material providing a distributed electrical path between the heating conductor and the sensing conductor, a first current sensor to sense a current in the heating conductor and a second current sensor to sense a current in the sensing conductor. A method of controlling a temperature of a heating pad, including the steps of: warming the heating pad to at least a first predetermined temperature by use of an adjustable on/off signal to the controllable switch, measuring currents through an NTC material or a combination of a PTC material and an NTC material; and maintaining a temperature of the heating pad to within a predetermined temperature range by use of the adjustable on/off signal to the controllable switch.

Abstract: A controllable heating pad, having a heating conductor embedded in the heating pad, a sensing conductor embedded in the heating pad, a resistive material providing a distributed electrical path between the heating conductor and the sensing conductor, a first current sensor to sense a current in the heating conductor and a second current sensor to sense a current in the sensing conductor. A method of controlling a temperature of a heating pad, including the steps of: warming the heating pad to at least a first predetermined temperature by use of an adjustable on/off signal to the controllable switch, measuring currents through an NTC material or a combination of a PTC material and an NTC material; and maintaining a temperature of the heating pad to within a predetermined temperature range by use of the adjustable on/off signal to the controllable switch.