Abstract: An electrical heating apparatus, and particularly a bedcover preferably in the form of a blanket, protected against an overheating condition and in which electrical current flow through a heating element is controlled by a pair of gate controlled bidirectional semiconductor switches electrically connected to one another in series and in front-to-front orientation. The gates of the semiconductor switches are connected through a temperature sensitive capacitor which triggers the semiconductor switches from a conductive to a nonconductive state in response to the sensing of an overheating condition.

Abstract: A control circuit for a dishwashing machine to economize its energy consumption and usage. In order to conserve energy, the dishwashing machine has a control system for automatically actuating the components such as the heating elements of the dishwashing machine. The control system can easily be adapted for utilization with many types of existing dishwashing machines, thereby permitting coupling of the control system with commercially available equipment with minimum installation and alteration of machine components.

Abstract: An improved radial flow parallel plate plasma etcher, whose more uniform etching rate of wafers is due to radially decreasing the spacing between the electrodes wherein the gap between the electrodes is greatest at the circumference and smallest at center of the electrodes.

Abstract: A method and apparatus for welding studs to a workpiece are provided. When the studs are welded to workpieces using a drawn-arc, stud welding technique, sometimes a coating of smut is deposited on the workpiece around the welded end of the stud. This coating detracts from the appearance of the stud and workpiece. Further, if the workpiece is to be covered with a coating material, the coating of smut must first be removed, resulting in an extra operation. It has been found that the coating of smut will not be deposited if, during the stud welding cycle, gas is directed toward the weld area in a swirling manner around the end of stud where the weld occurs.

Abstract: A plasma etching device having a quartz cylinder surrounded by RF energized electrodes or coils, contains a slotted aluminum tube into which wafers for etching are supported and processed. Each of the slots of the aluminum tube is provided with a shield extending longitudinally of the slot to intercept optical radiation, including deleterious ultraviolet (UV) radiation, of the plasma from entering the tube while still permitting the active etchant particles to pass into the tube to act on the wafers.

Abstract: A control instrument is used for the manually continuously adjustable supply of electric power to electric hot plates in the form of individual power pulses. The control instrument contains a switch, operated by a bimetallic member, whose heater is controlled by an electronic circuit and supplies current to the heating means in individual half-waves. An automatic initial cooking device with an electronic timing member is provided which, during the initial cooking phase, reduces the power supply to heater in a predetermined ratio and consequently correspondingly increases the power supplied to the electric hot plate. The automatic initial cooking device is automatically switched on by the control instrument knob. By rotating the control knob beyond a median power limit the automatic initial cooking device is switched off.

Abstract: A space heater having two heating elements and a motor/fan combination for circulating air over the heating elements to supply heated air to an environment includes a system for controlling the operation of the heating elements and the motor in response to heating requirements of the environment. The control system includes a first circuit for sensing temperature to determine a heating requirement to maintain a desired ambient temperature of the environment, a second circuit for independently activating and deactivating the heating elements in according with the heating requirements determined by the first circuit, and a third circuit for activating, deactivating, and variably controlling the volume of air circulated by the motor/fan in accordance with heating requirements determined by the first circuit. The heater housing includes a main housing portion housing the heating elements, an ambient air intake opening, a heated air exhaust vent, and the motor/fan.

Abstract: A method for cutting by a plasma arc in which the nozzle is directly contacted with the base metal to be cut and is at the same electrical potential, and wherein the electrode is first approached near to the base metal to strike the arc and then withdrawn from it to an appropriate cutting distance, and which permits a thinner cutting line to be made and thinner materials to be cut.

Abstract: A helicopter deicing control system (10) is provided for selectively distributing D.C. electrical power to a plurality of deicing segments (80, 90) on main and tail rotor blades with only two slip-ring assemblies (60 and 61, 62 and 63) for each rotor drive shaft. A power distribution controller (20) receives electrical power from the helicopter's onboard, fixed electrical power system and provides an output signal including power and control D.C. electrical signals of opposite polarities. A distributor (70) receives the output signal from controller (20) and increments a rotary switch (74) upon receipt of a D.C. electrical control signal, and distributes power to the main rotor deicing segment (90) connected to the rotary switch (74) contact then engaged upon the receipt of a D.C. electrical power signal so as to sequentially deliver D.C. electrical power to the desired main rotor deicing segment.

Abstract: Workpieces, such as structural steel, are cut under water by a plasma burner having a needle electrode with the plasma arc slightly under the water level and the plasma arc being enveloped during the ignition and cutting by a compressed air sheath outside the nozzle which strongly contracts the plasma cutting arc.

Abstract: Plasma burner provided with an electrode holder for the support of a cently arranged electrode and an outer electrode, a device for applying an electrical voltage for producing an electric arc between the electrodes and a device for the supply of gas to the electric arc area of the electrodes. The electrodes constitute a continuously consumable electrode system in which the outer electrode has the shape of a pipe while the other electrode is pipe- or rod-shaped and coaxially arranged within the outer electrode so as to define therebetween a passage of annular cross-section. The electrode holder is designed to conduct gas through the passage forwards to a front, free end of the electrodes where the electric discharge occurs from the end of the inner electrode.

Abstract: A thermostat is disclosed which includes a bimetal element in the form of an elongated strip and a trip mechanism formed by an elongated metal strip and a member having a U-shaped portion operative as a spring and an arm portion projecting from one leg of the U-shaped portion to form a reset lever. The trip mechanism operates electrical contacts on metal strips and has an over-center operation to provide a snap action. The thermostat is connectable in series with a cooking temperature control thermostat of a popcorn cooking machine to protect against dangerously high operating temperatures.

Abstract: Apparatus for cutting notches in the outer surface of a cylindrical drum includes a machine frame, and a laser cutting set which provides a laser beam to cut the notches in the drum. The notches are provided to allow sheet steel strips to be later fitted on the drum, and thus form a cutting tool useful in the production of collapsible box blanks. The apparatus also includes a movable carriage for supporting the laser cutting set, and a mounting shaft is supported by the carriage for rotatably supporting the drum. A drive wheel, coaxially fitted to the mounting shaft, rotates the shaft, and the drive wheel has an engagement surface which corresponds to a cutting edge diameter later defined by the positions which the cutting edges of the steel strips assume beyond the outer circumferential surface of the drum.

Abstract: The initial height of a flame cutter to a workpiece located under a liquid is automatically adjusted by jointly moving the flame cutter and a sensor toward the workpiece before the cutting operation until the sensor touches the workpiece surface whereupon a signal is sent for turning off the height adjustment device and for removing the sensor from the workpiece.

Abstract: Glow plugs (16), (17), (18), (19) for a Diesel engine are connected to a power source (12) through a switch (13) to receive electrical power. A time constant circuit including a capacitor (32) and resistors (31), (33) is connected to the power source (12) through another switch (27) together with the glow plugs (16), (17), (18), (19). The time constant circuit is constructed so that the voltage across the capacitor (32 ) is proportional to the temperature of the glow plugs (16), (17), (18), (19). A comparator (34) opens the switches (13), (27) to disconnect the power source (12) from the glow plugs (16), (17), (18), (19) and time constant circuit when the voltage across the capacitor (32) is above a predetermined value and closes the switches (13), (22) to connect the power source (12 ) to the glow plugs (16), (17), (18), (19) and time constant circuit when the voltage across the capacitor (32) is below the predetermined value.

Abstract: A solid-state control circuit for selectively operating a deep fat fryer in a normal cook mode, a lower temperature hold mode, a fat melt mode and a safety thermostat test mode. During operation in the cook mode, a reference bias voltage is coupled to one input of a voltage comparator, and an operating bias voltage dependent on the temperature control setting and the actual cooking fat temperature sensed by a NTC resistive sensor is coupled to a second input of the comparator such that the comparator is effective to enable heating elements in the cooking fat when the fat temperature drops below the preset level. After a predetermined time interval during which the fryer is not being used, a timing circuit acts to vary the reference bias voltage and the operating bias voltage supplied to the comparator and thereby reduce the temperature of the fat to the lower preset hold mode temperature.

Abstract: A power control system is disclosed which controls the power output of one or more resistive heating elements in response to operator selected power level settings. Control of power to the elements is accomplished by generating a multi-bit binary word representing a selected power level, each bit being operative to control the application of power to the element during a different control interval. A control word is generated for each element and is updated once during every associated control period, a period comprising a number of intervals equal to the number of heating elements. The heating elements are of a type which draw a relatively high current during a transient heat-up period. The application of power to other elements is inhibited when one of the elements is having power applied thereto during its transient period. Power control for each element is staggered by testing a bit of different positional value in each word during any given interval.

Abstract: In an electric bedcover of a type wherein a safety thermostat having a bimetallic element is adapted to deenergize a heater when the bimetallic element is heated sufficiently, as when an overheated condition occurs, an elongated flexible sensor of a type comprising a pair of conductors spaced from each other by a layer of material having a negative temperature coefficient of resistance is adapted to influence the bimetallic element through a resistor, which is mounted for heat dissipation to the bimetallic element, and a first circuit branch comprising the resistor, the conductors, and the layer between the conductors, in series with each other, is connected so as to maintain the conductors at different potentials when the heater operates, and so as to conduct sufficient current to cause the resistor to conduct sufficient heat to cause the bimetallic element to open the contacts when some part of the layer between the conductors is heated so as to act as an electrical conductor having a low impedance rather t

Abstract: An arc welding or plasma cutting apparatus has a current source as well as a set of controls for the welding or cutting process and includes a diagnosis apparatus which can be hooked up to the current source and/or the controls.

Abstract: A temperature-responsive control system is provided for sensing the temperature of a heating circuit and automatically shutting off the input power when the temperature exceeds an acceptable range. Manually operated means are provided for initiating heating only when the temperature is within the acceptable range.