Abstract: A control circuit uses an adjustable resistance to generate a first control signal whose amplitude varies with the setting of the resistance and a second, step-like control signal whose level changes from a first to a second level at a predetermined setting of the resistance. The variable resistance is coupled to the collector of one of a pair of transistors whose emitters are commonly connected to a reference potential. The adjustable resistance's tap, which provides the first control signal, is connected to the base of the one transistor. A collector impedance and the variable resistance are coupled between the collector circuit of the one transistor and a voltage source. An output of the impedance is connected to the base of the other transistor, whose collector provides the second control signal.

Abstract: A manual electric cigar lighter for automobiles and the like, comprising a holder device presenting an outwardly facing socket, and a unique ignitor plug receivable in the socket. Disposed at the inner end of the plug is a heating element which is electrically connected in circuit with a heat-responsive switch that is also carried by the plug. The socket in addition to its grounding circuit has a "hot" contact which is engageable with a cooperable contact on the plug to close the circuit through the heating element. The plug comprises a manually operable part by which the heat-responsive switch can be closed, thereby to complete the heating circuit through the element. A bimetallic member is also carried by the plug, engageable with one of the switch parts and always normally lying in a closed-circuit position when cold.

Abstract: An air drier has a control circuit for controlling heating of air entering the drier to maintain the difference between the temperature of air leaving the drier and that of ambient or incoming air at a predetermined value. The control circuit is compensated for variations in ambient air temperature such that as ambient air temperature decreases the control circuit tends to maintain the temperature difference at a higher value to ensure that the drying times are not unduly lengthened. A signal for terminating operation of the drier is derived by monitoring the difference between the actual value of the temperature difference and the desired value, and the mean heater power, and for terminating the drying cycle when a signal representative of the sum of the two values passes through a predetermined value.

Abstract: A heating assembly for a fused bath is disclosed. The assembly includes a heating element within a tube. Also, disposed within the tube is a first thermocouple. A second thermocouple is positioned in the bath outside the tube. Control means are connected to the heating elements and thermocouples so that the heating of the bath is performed responsive to the temperature sensed by the second thermocouple; but, if the first thermocouple detects heat in the tube greater than a given value it will interrupt the heating operation to prevent damage to the heating elements due to over-heating.

Abstract: A cooking apparatus employing induction heating is normally constructed so as to utilize a metal housing supporting a cook top upon which there is located at least one induction heating coil. The housing normally contains an electronic "package" for use in supplying power to the coil or coils used and a fan for circulating air through the housing so as to maintain the temperature of the electronic components employed sufficiently low that they will not be damaged by heat. In the disclosed apparatus a thermistor is mounted on the housing adjacent to the wires connecting the electronic components to the heating coil or coils used. This thermistor is used to control the flow of current through an SCR or a triac acting as a switch in a circuit containing the fan motor.

Abstract: In a gas chromatography system of the type including an oven for the GC column, and an electric heater for controllably heating the oven; an improved system is disclosed for controllably opening and closing the oven door to enable a fully controlled heat leak, thereby to stabilize the oven temperature at a desired set point. A signal indicative by first or second conditions of an oven temperature above or below the set point is generated. A heater power control responds to one of the signal conditions by effecting heating of the oven. Bi-directional door motor and actuator means are provided for opening and closing the oven door over a prescribed operating range, and these means are enabled to operate for a predetermined period upon the signal in its first or second condition departing from preset threshold values for a predetermined period whereby closing or opening of the oven door is effected in incremental steps.

Abstract: An automatic electric cigar lighter, and especially a cigar lighter igniting unit as used for automobiles and the like. The cigar lighter has a holder which presents an outwardly facing socket, and embraces a unique ignitor plug that is received and stored in the socket. At its inner end the plug has a heating element for electrical connection in the circuit of a heat-responsive switch which is also carried by the plug. The latter comprises a manually operable part by which the heat-responsive switch can be closed to complete the heating circuit through the element. A bimetallic member is also carried by the plug, being engageable with one of the switch parts and normally having a circuit-opening position wherein it maintains the one switch part separated from the other. The member is shifted to a closed-circuit position when the plug is actuated. In both positions it receives radiant heat when the heating element is incandescent.

Abstract: A self-regulating heating article comprising a layer of material exhibiting a positive temperature coefficient of resistance (PTC) and said PTC layer having at least partially contiguous therewith at least one layer of constant wattage output material. The article operates such that when connected to an electric power source, the current flows through at least a portion of the thickness of the PTC layer and of the constant wattage layer. In a preferred embodiment, upon heating the article, a change in dimensions as well as activation of an adhesive occurs.

Abstract: An electrical furnace heater construction having electrical heaters carried by a frame and having a current fused drawer-like lead unit movably carried by the frame and having leads for directly and electrically interconnecting to terminals of the heaters when the unit is in one position relative to the frame, the frame having terminals for electrically interconnecting the leads of the unit to power source leads so that the power source leads will be directly and electrically interconnected to the terminals of the heaters by the unit. A temperature responsive power device is carried by the frame and is responsive to the output temperature effect of the electrical heaters, the temperature responsive power device being operatively associated with the unit to move the unit out of the one position thereof to disconnect the leads thereof from the terminals of the heater when the temperature responsive device senses a certain adverse output temperature effect of said electrical heaters.

Abstract: A thermostatically controlled pre-weld heater is described in which a temperature sensor is mounted, intermediate the legs of a pre-weld heater, in a position to sense accurately, and then thereby to control, the temperature of the workpiece so as to accurately control the temperature of the area to be welded by opening and closing the circuit to the electrical current supplied to the heater coil in the legs of the pre-weld heater.

Abstract: A heater element is formed by disposing a pair of heater wires and a pair of thermocouple wires and a powdered mineral material in a metal sheath which is subjected to repeated drawing and annealing operations and is then cut to a desired length after which at one end, the heater wires are welded together and the thermocouple wires are welded to the sheath and the sheath is welded to form a closed end wall. At the opposite end, the heater and thermocouple wires are connected to suitable connection wires. The sheath is formed into a helical coil structure and installed in a runnerless bushing of a plastic molding machine.

Abstract: A potter's oven includes an electrical heating element for controlling the temperature in the oven. Power to this heating element is controlled by a bimetallic switch and an electrically energized heater therefor and the percentage of power supplied to the oven heating element is controlled in dependence upon the value of resistance in series with the heater for the bimetallic switch. The value of this resistance is increased in stepwise fashion under control of at least one sensor which determines the outside wall temperature of the oven, the temperature at which the sensor responds being chosen to cause the temperature inside the oven to reach a predetermined value and to hold such value for a predetermined time.

Abstract: A method for detecting a fire in a microwave oven heating cavity by sensing the time dependent "in-situ" humidity and the temperature environmental conditions of a microwave oven heating cavity in a microwave oven. The humidity sensor and the temperature sensor connect to a programmable controller in the microwave oven. When the sensed "in-situ" relative humidity decreases and the sensed temperature increases within a predetermined time interval, there is a fire in the cavity. The programmable controller processing the sampled humidity and temperature signal information turns off the microwave oven upon sensing the decreasing humidity and increasing temperature within the predetermined time interval indicating a fire.

Abstract: An electrical heater construction having a frame carrying electrical heaters and a movable drawer-like unit that is adapted to interconnect power source leads to the heaters when the unit is in one position thereof relative to the frame, the frame carrying a movable latch member that is operatively associated with the unit to latch the unit in an out position thereof when the unit is moved out of the one position thereof to the out position to disconnect the power source leads from the heaters whereby the unit cannot be moved in any direction from the out position thereof until the unit is unlatched from the latch member by the latch member being manually moved to an unlatching position thereof.

Abstract: A cartridge heater with improved thermocouple comprising a tubular metal sheath with a front end having a central opening therein, a metal plug engaged in and closing said opening, a filler of dielectric material in the sheath rearward of the plug, a resistance wire within and extending longitudinally of the sheath and supported by said filler, said plug having a pair of circumferentially spaced axially extending and radially outwardly opening grooves, a pair of elongate thermocouple wires supported by the filler within the sheath and having front end portions tightly engaged in and between in said opening and grooves, and an annular weld about the foremost line of contact between said sheath and plug and across the forward ends of said grooves.

Abstract: A cartridge heater and multiple thermocouple assembly comprising an elongate outer heavy walled structurally supportive metal sheath, an elongate thin walled, yieldable, orienting metal tube extending through the sheath and defining an annulus, a plurality of axially aligned pairs of thermocouple cables and spacer rods fixed to the tube in circumferential spaced parallel relationship and extending through the annulus in interfering engagement with the sheath, a resistance element extending through the tube, conductor terminals for the element accessible at one end of the tube and a filler of particulate dielectric material compacted in the tube about the element and in the annulus between the sheath, tube and adjacent pairs of cables and rods, said cables being of different lengths and having outer ends with conductors accessible at an end of the annulus and having inner ends with thermocouple junctions located at spaced points longitudinally of the sheath.

Abstract: A cartridge heater with improved thermocouple comprising a tubular metal sheath with a front end, a metal plug closing the front end, a filler of dielectric material in the sheath rearward of the plug and an elongate resistance wire supported by the filler, said plug having a pair of spaced axially extending through holes, elongate insulating tubes with front and rear ends and engaged in said holes with their front ends spaced predetermined limited distances from the open front ends of the holes, a pair of elongate thermocouple wires with front end portions engaged through the sleeves and projecting forwardly therefrom and rear portions supported in said filler and projecting rearwardly through and from the sheath and metal deposits in the forward position of the holes in the plug in sealing engagement therewith and in heat conducting contact with the thermocouple wires.

Abstract: An apparatus for heating fluids includes a pipe through which the fluid to be heated flows having a ferromagnetic pipe attached in heat-transmitting relationship thereto. An insulated wire extends longitudinally through the ferromagnetic pipe and is electrically connected in series therewith. The secondary windings of a pair of transformers are connected in series with each other and the ferromagnetic pipe by the insulated wire and the primary windings of the transformers are connected to a source of alternating current. A control responsive to the temperature of the fluid in the fluid conveying pipe is provided for regulating the power output to the series connected ferromagnetic pipe and insulated wire by, in alternative embodiments, disconnecting the transformers from the circuit, reversing the polarity of one transformer secondary with respect to the secondary of the other or bypassing one of the transformers.

Abstract: A torpedo heater device for plastic molding or diecasting equipment comprised of a novel casing having an integral heater core and means to seal the casing for retaining the heater core in place and preventing loss of thermal transmitting packing contained in the casing, and which is structured to receive the heater core in the area close to its tip, which is tapered. The casing may also include a probe for a thermocouple or a thermocouple well.

Abstract: A contactor or switch to an electrically powered unit, such as a motor, is controlled by a condition responsive circuit which may include facilities for changing the response condition of the circuit and/or facilities responsive to several conditions, such as temperature and excessive current.

Abstract: In apparatus for deep fat frying, control circuitry is provided for regulating the temperature of heating elements. During cooking the heating elements are immersed in cooking fluid and are maintained at a selected temperature by an operating thermostat. Two high limit thermostats are provided to turn off the heaters if the temperature exceeds a predetermined safe limit. For cleaning, the heating elements are raised out of the cooking fluid and automatically disconnected from the operating and first high-limit thermostats. The heaters are cyclically actuated and deactuated by a thermal time delay relay, to gradually raising the heater temperature to achieve pyrolytic cleaning of the heating elements. The second high-limit thermostat turns off the heating elements when a predetermined temperature is reached, ending pyrolytic cleaning.