Abstract: An electric blanket includes a heating element comprising inner and outer coaxial coil conductors separated by an electrically insulating layer and connected by a diode. A control assembly is connected to the heating element by a simple two-core flexible electrical cable and incorporates a thyristor and a thyristor control circuit to vary the supply of current to the heating element. Protective diodes are connected in parallel with the main heating conductor and also in parallel with the thyristor. Should the heating element overheat the insulating layer breaks down causing a short circuit between the conductors and the surge of current allowed by the protective diodes causes a fuse to blow. The conductor is always in series with the protective diodes so that in the event of transient breakdown of one of the diodes the resistance of the conductor prevents fuse operation.

Abstract: An electric toaster includes a pair of electrically heatable plates (16) which have toasting surfaces (18) that can be brought into contact with opposed surfaces of a slice of bread (14) or other item to be toasted. The temperatures of the toasting surfaces (18) can be adjusted, for example over a range substantially equal to 230.degree. C. to 300.degree. C., to enable the degree of browning of the bread to be controlled.

Abstract: An electric blanket or the like includes a heating element having at least two elongate electrodes separated by a heating material that has a positive temperature coefficient of resistance and that will generate heat when a current passes through it. At least one of the electrodes is a resistive heating conductor, such as nichrome wire and is so arranged that heating current supplied to the heating element from an electrical supply will flow through both the at least one conductor and the heating material.

Abstract: A heating circuit for an electric blanket or the like comprises a heating conductor, a sensor conductor and separating means which separates the conductors and has an impedance that falls with increasing temperature and/or which will melt in the event of overheating to allow contact between the conductors. A thermal fuse and a first diode are connected in series with the heating conductor between AC supply input terminals, and a resistor is thermally coupled to the thermal fuse and electrically connected such that the resistor and the impedance of the separating means are connected in series between the input terminals. A drop in the impedance of the separating means due to overheating will cause the current through the resistor to increase, so heating the resistor to cause the thermal fuse to disconnect the circuit from the supply.

Abstract: A heating circuit for an electric blanket or the like comprises a cable (1) formed from a heater conductor (2) separated from a sensor conductor (3) by temperature sensitive material (4) and two series resistor-diode pairs (R1-D1 and R2-D2) each connected between ends of the conductors (2, 3) so that each pair conducts in series with the impedance (Z) of the material (4) during respective half-cycles of an AC mains supply, the arrangement being such that general overheating of the cable (1) or localized overheating anywhere along its length reduces the impedance (Z), (possibly to zero if the material (4) melts), such that the current through one or both of the resistors (R1, R2) heats the resistor(s) and blows a thermal fuse (F) to terminate heating. The thermal fuse (F) may be replaced by a resettable interruption element, namely a self-regulating PTC resistive element.

Abstract: A heating circuit, in particular for an electric blanket or pad, comprises an elongate heating conductor and switch connected in series between input terminals for connection to an AC supply. Switch control is operative to close the switch to cause current to flow through the heating conductor. The circuit further comprises a sensor conductor coextensive with the heating conductor, and a temperature sensitive resistance coextensive with the heating and sensor conductors and having an impedance that falls with increasing temperature. A resistor is connected in series with the sensor conductor such that a current dependent on the impedance of the temperature sensitive resistance flows through the resistor, whereby the voltage across the resistor varies with said impedance. Voltage sensing structure is responsive to the voltage across the resistor reaching a predetermined value to inhibit operation of the switch control, thereby to provide normal and/or overtemperature control.

Abstract: A heating circuit, in particular for electric blankets or pads, comprises a first, heating conductor and a second conductor separated by a material which has an impedance that falls with increasing temperature and/or which will melt in the event of overheating to allow contact between the two conductors. A half-wave rectifier and a thermally-operative circuit interruption means are connected in series with the heating conductor across an AC supply. A resistor is electrically connected to the second conductor such that the resistance and the impedance of said material are connected in series across the supply. The resistor is thermally coupled to the circuit interruption means whereby, in the event of overheating of said material, the drop in the impedance of the material to a reduced or zero value will cause the current through the resistor to increase to heat the resistor, which causes the circuit interruption means to disconnect the circuit from the supply.

Abstract: A heating circuit comprises input terminals for connection to an AC supply, an elongate heating conductor and a switch connected in series between the input terminals, a switch control operative to close the switch to cause AC current to flow from the supply through the heating conductor, an elongate sensor conductor spaced from the heating conductor, and a temperature sensitive element disposed between the heating and sensor conductors and responsive to over-heating at any position along the length of the heating conductor to drop substantially in impedance at that position to connect the sensor conductor to the potential of the heating conductor at that position.