Abstract: A controlled temperature hot melt adhesive dispensing system including three closed loop temperature control arrangements along a flow path for hot melt adhesive extending from an upstream adhesive source to a downstream adhesive dispenser. As disclosed, each closed loop temperature control arrangement includes a comparator which compares the temperature sensed by a temperature sensor with a setpoint temperature to produce a control signal for a heater in the temperature control arrangement. The temperature control loops are located along the adhesive flow path so that the second closed loop temperature controller is upstream from the first closed loop temperature controller; and the third closed loop temperature controller is upstream from both the first and second temperature controllers. A first feedback circuit scales and integrates the control signal from the first location to produce a first feedback circuit output which adjusts the setpoint temperature at the second location.

Abstract: In a blackbody furnace comprises a furnace provided with at least one aperture at an end along a horizontal direction with the interior thereof being hollow and a polyhedral heating unit is provided enveloping the furnace, each surface of the aperture, target and side surfaces of the heating unit is divided into two or three zones, and these zones of the heating unit are controlled in such manner that the temperature of the aperture comes to have a prescribed relationship with respect to the temperature of the target of the blackbody furnace, whereby the effective cavity emissivity of the blackbody furnace is always unity.

Abstract: A step controller for a water heater includes a plurality of individual electrical elements to maintain a predetermined minimum temperature in accordance with a sensed temperature signal and a preset desired temperature signal in combination with a dead band signal. The heating elements are turned "on" and "off" in a random sequence whenever a change is required, and in accordance with a binomial distribution so as to substantially equalize the operating period of the heating elements. The controller includes a microprocessor unit to periodically sense the signals of a sensor and a preset potentiometer, and also operates to store the on-off status of the heating elements, each of which is assigned a binary load indentifying number. The microprocessor includes a psuedo-random binary number generator for generating the load identifying numbers.

Abstract: A time switch (100) comprises terminals (110) spaced around a slip ring (108) connected to a voltage source (V). A motor (104) drives a brush (102) to sequentially connect the terminals (110) to the slip ring (108) to energize the terminals in sequence. Each terminal (110)--as shown for one of them designated 112--is connected via a respective transistor (116) and manually operable switch (124) to a pair of common output conductors or bus-bars (130, 132), whereby for each successive period of time corresponding to each successive terminal (110) being energized the conductors (130, 132) are energized in accordance with the setting of a respective one of the switches. Thus, a desired time-varying pattern of energization of the conductors (130, 132) to accomplish a control function, e.g. the control of a central heating system to provide different heat outputs at different times of the day, can be set up at will simply by adjusting the various switches (124).

Abstract: The provision in a range having an electrically energizable heating unit and a control for selectively causing energization of the heating unit from a power supply of an improved circuit for causing time-delayed initiation of energization of the heating unit for a period of time which is a function of the period of inrush current which occurs when the heating unit is energized. The circuit causes such a delay in the event the circuit senses a preselected power delivery from the power supply at the time of attempted initiation of energization of the heating unit. The novel circuit is advantageously utilized in a range having a plurality of electrically energizable heating units and assures that the heating units will be sequentially energized with a time delay between initiation of energization of each so that the total inrush current is substantially less than the sum of all of the inrush currents of the heating units concurrently attempted to be energized.

Abstract: The device for gluing sheet-like textile articles contains a spreading station (15), a heating station (16), a pressing station (17) and a take-off station (18). The plate-shaped heating zones consist of several hollow-profile heaters (25) which are arranged next to one another and on the rear contact side (28) of which panel heaters are attached, each panel heater having at least one electrically heatable heating device (heating wire). The heating wires can be controlled each individually or in groups.

Abstract: A system for improving the starting of indirect and direct injection diesel engines in cold weather, including glowplugs powered by a source of electrical potential for heating the diesel fuel and circuitry for controlling the operation of the glowplugs.

Abstract: An arrangement for monitoring the approximate temperature of a resistive heating element selectively energized at a plurality of power levels in response to the selection by an operator of one of a plurality of power settings including OFF, which includes a heater energy counter to provide approximate heating element temperature information. The heater energy counter is incremented at a rate which is approximately proportional to the rate of increase of the temperature of the heating element when energized at the selected power level. In one form of the invention, the counter is decremented when a lower power setting or an OFF setting is selected, at a rate which is approximately proportional to the rate at which the temperature of the heating element decreases in cooling down to the temperature level associated with the new power setting. By this arrangement, the count of the counter approximately tracks the heating element temperature, thereby providing approximate temperature information.

Abstract: A perimeter heat loss control system for electrical heaters and/or radiant ceiling panels around the periphery of a building has the heaters divided into zones, usually one zone for each outside wall. In a zone, a radiant heat responsive heat flow sensor faces the outside wall for the zone and generates a wall heat rate signal; a thermal sensor is positioned adjacent to one heater to generate a heat rate signal. A zone comparator uses the sensor signals to generate an error signal representative of deviation of the differential between the rate of heat flow through the zone wall and the rate of heat generation in the zone relative to a predetermined preset value. That error signal is applied to a power control to control all heaters in the zone, proportionally varying the input to the heaters until a balanced heat loss condition is realized.

Abstract: Apparatus which can control a remotely-located electric storage heater from a central location without requiring control wires between the central location and the remote location is disclosed. Control signals indicating the heating cycle and representative of the outside ambient temperature are generated by apparatus at the central location and encoded by high-frequency signals which are superimposed on the normal power line voltage. At remote locations each electric storage heater is equipped with a receiver unit which decodes the high frequency control signals superimposed on the power line. The receiver unit then operates a solid state relay to convert the coded signals into the normal control signals which operate the heater.

Abstract: An apparatus for sterilizing a thermoplastic strip moving forward stepwise and used in the production of hot-formed containers which, after forming, are filled and sealed in a sterile atmosphere, wherein prior to the strip softening operation, the surface of said strip which is subsequently to constitute the inside face of the containers, is exposed evenly and intermittently, in successive portions and for a very short period of time, to a temperature higher than that of the softening point of the said thermoplastic strip and which is dependent on the desired extent of bacterial destruction.

Abstract: An electrically heatable self-defrosting windshield has a transparent panel, two low-resistance groups of wires embedded in the panel and defining a primary zone requiring rapid heating, and at least one high-resistance group of wires embedded in the panel and defining a secondary zone adjacent the primary zone and not requiring rapid heating. A switch connected to the wire groups and to an electric power source is movable between a fast-heat position connecting the two low-resistance groups in parallel with each other across the source and effectively disconnecting the high-resistance wires, and a slow-heat position connecting the two low-resistance groups in series with each other and jointly in parallel with the high-resistance groups across the source. The total resistance of the groups in the fast-heat position is generally the same as in the slow-heat position.

Abstract: A controller for a water heater having a plurality of individual electrical heating elements changes the number of energized elements to maintain a predetermined minimum temperature. The number of "on" elements is related to the difference between sensed water temperature and a preset water temperature divided by a dead band factor. The heating elements are turned "on" and "off" in a programmed sequence whenever a change is required to optimize the equalization of operating time of the elements. The controller includes a microprocessor which monitors turn "on" or "off" of each element to continuously develop the "on" operational period of each element in relationship to all of the other heating elements since system initialization. The operation period is made relative to the load with the shortest period by substracting the lowest "on" time from all other loads so as to reduce the required memory size.

Abstract: The bushing temperature measurement device is a microprocessor based sensor which determines the temperature across a multi-segment electrical resistance heated glass fiber producing bushing. The temperature change is determined by calculating the change in resistance of each segment of the bushing by sensing the voltage drop across that segment and dividing by the current flowing in that segment. All measurements of voltage and current are taken simultaneously and averaged over several cycles. The microprocessor, through appropriate output circuitry, alerts other process controls to eliminate any change in temperature.

Abstract: An electrical radiant heating body has two concentric heating zones with independently operable heating resistors. On only switching in the central zone, the associated heating resistor has a very high power which, on connecting in the outer zone, can be reduced by the connection in series of a heating resistor in the outer zone, so that there is a uniform heating surface loading for the total heating surface.The thermometer probe of a thermal cut-out projects over the heating surface and has two contacts operating at different temperatures, one of them being a changeover contact.

Abstract: A method and control system for operating a refrigeration unit to permit random loading and unloading sequences of multiple compressors and unloaders. The random loading and unloading sequences of the two circuits of compressors and unloaders is performed by a microprocessor. A random sequence is selected at start-up and the selected sequence loads the compressors to full load, where upon another random sequence is selected to unload the compressors.The compressors are also loaded in response to the water temperature leaving the chiller. The leaving water temperature is compensated for by a return water temperature which determines the temperature drop through the heat exchanger. The temperature drop is divided by the number of active stages to determine the drop/stage, which is an indication of how the leaving water temperature will change when a capacity stage is either added or subtracted.

Abstract: A method and apparatus are described for controlling the temperature of a heated wire, such as on a wire sealer for plastic film. Temperature control is based upon measurements of changes in the resistance of the wire as it is heated, through bridge circuit and microprocessor techniques.

Abstract: An instantaneous fluid heater having a combined safety shut-off and temperature regulator includes a hollow heater block having a fluid inlet, a fluid outlet and inner walls defining a plurality of interconnected heating chambers forming a serpentine fluid flow path from the inlet to the outlet. A separate electric heating element is positioned in each chamber and a separate thermostat is positioned at the downstream end of each chamber for opening and closing an electrical circuit in response to the temperature at the downstream end. An electrical sequence switching arrangement cooperates with the thermostats to sequentially energize the heating elements, beginning with the heating element in the most downstream chamber.

Abstract: The output of a first bridge circuit including as one component element a thermistor for detecting the temperature of a pan is compared with a preset value in a first operational amplifier. The first operational amplifier provides a low level output when the detected temperature is below a predetermined temperature. When this low level output is supplied to a second operational amplifier, the output thereof goes to a high level to turn on a transistor so as to energize a relay for passing current to a cooking heater. When a cooking end temperature is reached, the internal resistance of the thermistor is reduced, and as a result the output of the first operational amplifier goes to a high level, causing the output of the second operational amplifier to go to a low level. Thus, a warming heater is energized while the cooking heater is de-energized.

Abstract: A system for space heating a dwelling, office and the like having a plurality of heating means and having a control mechanism for sequentially actuating said heating means to actuate only one said heating means at a time.

Abstract: A peak load control apparatus with operating mode selection for an electric heating system having a plurality of electric heating units arranged in two or more groups in different rooms is disclosed. When the current carried by the feeder line exceeds a predetermined value a peak load trigger or flip-flop which receives a signal proportional to the feeder current from a detector delivers a peak load signal to a first control circuit or monostable which cuts power to a first selected group of heating units for a predetermined period, and to a second time control circuit or monostable which cuts power to a second selected group of heating substantially at the end of the period during which power is cut off to the first group of heating units. The heating units are provided with programmable thermostats connected to operating mode selector switches which are connected to the feeder line.

Abstract: A power control system for a heating element in a cooking appliance having a plurality of possible power settings which provides transient Fast-Heat and Fast-Cool operating modes initiated in response to user-initiated changes to higher or lower appliance power settings, respectively, to reduce the response required for the heating element temperature to reach the operating temperature associated with the new power setting. Approximate heating element temperature information is provided to the control system by an energy counter which is incremented at a rate which is approximately proportional to the rate of increase of the heating element when energized at the power level being implemented. This information is used to prevent initiation of a transient mode if the temperature of the element when the change in setting is made is such that operation in that mode is likely to overshoot the desired new operating temperature.

Abstract: Control means for a drier for films or sheets using a minimum of electric power. A heater is connected to a semiconductor switch and an alternating-current power supply in series. An oscillator outputs a pulse to a turn-on terminal of the semiconductor switch via an OR gate in synchronization with a certain phase angle of the wave form of the alternating voltage turning on the semiconductor switch for approximately 10% of the rated value of the heater thereby preheating the heater. When an entrance sensor detects the presence of films or sheets entering the drier, a starting signal is sent to a flip-flop circuit which outputs a high level signal to the turn-on terminal of the semiconductor switch via the OR gate activating the heater to full rated value. The high level signal is also sent to the turn-on terminal of a second semiconductor switch activating a second heater and a blower.

Abstract: A temperature-adjustable electric soldering iron manipulable with a single hand to change the temperature of the iron comprises a handle, a circuit board, a Nichrome tip heating wire, a cover for the wire and a soldering tip. On the circuit board are two mercury switches, a diode, and five resistances, connected in a manner to provide four circuits connected with the Nichrome wire so that the tip can be heated to four different temperatures dependent upon which circuit is connected in series with the Nichrome wire. The circuit board is placed inside the handle and the mercury switches are arranged so that holding the handle in a completely horizontal position shuts off the electric circuit, but tilting it forward or backward, or turning it around to the left or to the right actuates the mercury switches by means of the function of the mercury drop which connects respective circuit contacts at either end of the switches to place a different one of the four circuits in series with the Nichrome wire.

Abstract: A novel cooking oven provides a plurality of elongated heating rods which are parallel to one another and surround the foodstuff to be cooked. The rods are energized sequentially by current flow controlled in magnitude and time to produce either black baking heat from the heating rods or infrared radiation from the heating rods by heating them to a red color. By sequentially heating the rods, the heat source in effect rotates around the foodstuff to be cooked to produce equal and even browning equivalent to that obtained by conventional rotisserie cooking in which the foodstuff is rotated relative to a stationary heat source. The oven may also be used in other heating modes such as pressurized cooking by containing the apparatus in a pressurized vessel with the heat sources consisting of inherent heat sources which will produce browning and crisping while heating in the pressurized mode.

Abstract: A control for modulating the duty cycle of diesel engine glow plugs has two heat sensitive, normally closed switches each thermally coupled to a respective positive temperature coefficient (PTC) of resistivity heater in turn thermally coupled to a common heat sink. The heat sensitive switches are serially connected to each other, to an ignition switch and to a glow plug relay. The PTC heaters are connected to a point between the heat sensitive switches and the relay and to ground. A third PTC heater is disposed on the heat sink intermediate the first and second heaters and thermally coupled to the heat sink. The third heater is connected to an alternator and serves to cut off power to the glow plugs after a selected after glow stage. The two heat sensitive switches can be selected to open at approximately the same temperature for a random operating mode or at slightly different temperatures for a sequential operating mode.

Abstract: A switching system for sequential connection of a plurality of loads to an alternating current supply comprises a computer for generating switch selection data in the form of serial bits along a single line to a distributor arrangement which decodes the selection data and provides control signals to switch devices which connect the loads to the supply. The distributor arrangement includes a circuit for inhibiting supply of the control signals to the respective switch devices unless the voltage of the supply phase connected by the device is substantially zero. Additionally the control signals are time-advanced with respect to the zero voltage conditions so that the switch devices can be placed in states in which they can connect a load before disconnection of a preceding load.

Abstract: A control arrangement for a multifunction appliance such as a cooking appliance wherein the control activity is distributed among a plurality of microprocessor based control circuits. In the exemplary embodiment each control circuit is associated with a different function of the appliance. The circuits are physically separated from one another and communicate on data bus lines. Due to the high transient conditions in such an appliance, the communications are in accordance with a redundant protocol to substantially eliminate erroneous data communication. The data bus protocol is devised such that deletion, addition and replacement of control circuits in a system, even to the point of substituting a circuit containing a different type of processor, is possible.

Abstract: A ceramic encased thermocouple placed within a kiln electrically controls an array of signal classifiers which, in turn, control the operation of the kiln heating elements. The temperature value at which the classifier array terminates the whole kiln heating operation is preselected as one of a plurality of discrete predetermined values corresponding to pyrometric cone temperature values.

Abstract: A load controller, primarily intended for use in systems having geographically distributed, energy utilizing loads, and employing stored energy heating apparatus. The controller (1, 10) disclosed, in conjunction with a stored energy heater (3, 4), when installed on an energy distribution system having a multiplicity of heaters and controllers, adjusts individual heater storage (3), providing adequate energy for varying heat requirements of individual heaters after a mandatory "off" period (46, 47, 49, 51), thereby greatly reducing the overall peak energy or demand requirements on a central energy source. Alternate embodiments utilize a microprocessor (300) to provide close control of heater storage and improve efficiency. Digital display (307) and a keyboard input are provided for adjusting system constants and evaluating unit operation.

Abstract: A control for modulating the duty cycle of diesel engine glow plugs has two heat sensitive, normally closed switches each thermally coupled to a respective positive temperature coefficient (PTC) of resistivity heater in turn thermally coupled to and mounted on a common heat sink. The heat sensitive switches are serially connected to each other, to an ignition switch and to a glow plug relay. The PTC heaters are connected to a point between the heat sensitive switches and the relay and to ground. A third PTC heater is mounted on the heat sink intermediate the first and second heaters and thermally coupled to the heat sink. The third heater is connected to an alternator and serves to cut off power to the glow plugs after a selected after glow stage. The two heat sensitive switches can be selected to open at approximately the same temperature for a random operating mode or at slightly different temperatures for a sequential operating mode.

Abstract: Control signals are transmitted through a.c. mains supply lines to control operation of electrical equipment powered from the supply lines. A near short-circuit condition is introduced across the a.c. mains supply lines, for example, by firing a thyristor connected in series with a fuse across the supply lines, for the final portion of positive half cycles of the mains supply voltage, thus holding the voltage to a near zero value for this length of time. A receiver coupled to the mains supply lines includes a zero crossing detector circuit which responds to the near zero voltage conditions across the supply lines to perform a particular control operation on an associated appliance connected to the receiver. Different control operations may be effected by defining the control signals over a group of half cycles of the a.c.

Abstract: A toaster-oven appliance has a control circuit which enables a user to program the operation of the appliance through a keyboard with audible feedback and which includes functional keys for selecting one mode of operation from available BAKE, BROIL, SLOW COOK, TIMER and TOAST modes, and numerical keys for entering a temperature, time interval and toast color. The BAKE and BROIL functions may be used with the TIMER function to provide TIME-BAKE and TIME-BROIL functions. An interactive digital display is provided to display a user selected function, temperature, time interval, or an error indication in the event that an impermissible entry is made. In the presently preferred embodiment that is described, the control circuit includes microprocessor-based programmable digital logic. The microprocessor operates under the direction of a master program.

Abstract: An electric boiler includes a conductivity control having a controller responsive to both steam pressure and electrode current. The controller is operative to open a boiler feed water discharge valve when either the steam pressure or electrode current falls below predetermined values to discharge water from the boiler for a predetermined time interval after which the controller closes the discharge valve and opens a feed water valve to initiate the delivery of feed water to the boiler chamber. When the pressure or current sensor senses the elevation of steam pressure or electrode current to second preselected levels the controller closes the feed water valve. In addition, if the sensors determine that the steam pressure or electrode current have risen to third preselective levels, a transfer valve is opened to transfer boiler water to a storage tank until the pressure or current level falls to fourth preselected levels.

Abstract: A thermal device for controlling the temperature of glow plugs in a diesel engine in which current is applied to the glow plugs from the battery through a relay, the relay in turn being actuated by a thermally controlled switch controlled by a heater. The heater applies heat to the thermal-sensitive switch. The relay also controls current through the heater so that the heater cycles in unison with the glow plugs. The thermally-operated switch includes a bimetallic element which is heated by the heater. The bimetallic element is mounted in the engine block so as to be subject to the same ambient temperature conditions as the glow plugs. A thermal timer responsive to the same ambient temperature conditions includes a resistance heater element energized from the alternator. The thermal timer switch de-energizes the relay when heated to a predetermined temperature.

Abstract: A power control arrangement for controlling the power output of a resistive heating element of the type having a fast thermal response time and a highly variable resistance with temperature. The power control arrangement includes a plurality of operator selectable power settings and an electronic switching system responsive to operator selection of these settings to rapidly couple and decouple a power supply to the element. The switching action is selected to permit rapid heat up of the element without causing an unacceptable current to flow and to prevent excessive cooling of the element after it reaches operating temperatures during steady state operation.

Abstract: A step controller for a water heater having a plurality of individual electrical heating elements changes the number of energized elements to maintain a predetermined minimum temperature. A thermistor sensor monitors the temperature of the water and generates a proportional signal. Preset potentiometers establish set point temperature signal and a dead band signal. The number of "on" elements is related to the difference between the sensed water temperature and the preset water temperature divided by the dead band factor. The heating elements are turned "on" and "off" in a predetermined sequence whenever a change is required. The sequence includes turning on the heating element which has been off for the longest period and turning off the heating element which has been on for the longest period.

Abstract: An apparatus for heat treatment (particularly asepticization) of contact lenses. The apparatus comprises a box having a housing adapted to receive a case for contact lenses and includes an electrical circuit comprising a power supply and at least one heating unit, with the heating unit having a heating resistor and a heat-sensitive switching device. The apparatus is characterized in that it comprises an electronic voltage threshold detection and programmed control.

Abstract: An apparatus to burn carbon bodies has at least two independently controllable electric resistance heating circuits, at least two temperature sensors and a comparator. Two or more regions of a selected carbon body can be independently heated by the two circuits. The actual temperature of each of those two or more regions can be monitored by corresponding temperature sensors connected to the comparator. The comparator controls each electric resistance heating circuit independently so as to minimize any difference between a preselected temperature and the actual temperature of each region.

Abstract: An energy saving food serving system for rethermalization of the food and for delivery prepared meals to locations remote from the place of preparation, such as to patients to hospitals and nursing homes. The system includes a mobile cart having its own rechargeable power pack that is utilized to propel the cart. The cart has separate bays, each having a tier of racks for carrying individual food serving trays. Each tray has one or more thermally isolated heat transfer devices which are selectably energized when the tray is in place on a rack in the cart. Preferably, each tray has a pair of heaters referred to herein as plate and bowl heaters and adapted to be operated by control means in either a continuous mode of operation or a rethermalization mode of operation.

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: A control for modulating the duty cycle of diesel engine glow plugs has two heat sensitive, normally closed switches each thermally coupled to a respective positive temperature coefficient (PTC) of resistivity heater in turn thermally coupled to a common heat sink. The heat sensitive switches are serially connected to each other, to an ignition switch and to a glow plug relay. The PTC heaters are connected to a point between the heat sensitive switches and the relay and to ground. A third PTC heater is disposed on the heat sink intermediate the first and second heaters and thermally coupled to the heat sink. The third heater is connected to an alternator and serves to cut off power to the glow plugs after a selected after glow stage. The two heat sensitive switches can be selected to open at approximately the same temperature for a random operating mode or at slightly different temperatures for a sequential operating mode.

Abstract: A cooking unit comprises at least two electric cooking plates, for example four such plates. Each plate can have a pair of electrical heating resistances. Power is supplied to each cooking plate via a switching unit, comprising a thermostat. Each thermostat switches on and off and is so arranged that when part or all of the power to one cooking plate is switched off power is supplied to another cooking plate connected downstream thereof.

Abstract: A load controller, primarily intended for use in systems having geographically distributed, energy utilizing loads, and employing stored energy heating apparatus. The controller (1, 10) disclosed, in conjunction with a stored energy heater (3, 4), when installed on an energy distribution system having a multiplicity of heaters and controllers, adjusts individual heater storage (3), providing adequate energy for varying heat requirements of individual heaters after a mandatory "off" period (46, 47, 49, 51), thereby greatly reducing the overall peak energy or demand requirements on a central energy source.

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 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: 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: An automatic microprocessor-based control system for a diffusion furnace in which the controller is dedicated to a single associated diffusion tube to provide all monitoring and control functions necessary for a variety of diffusion processes. The controller provides direct digital control of time, temperature and gas flow, and can be readily operated with a variety of control algorithms.

Abstract: A dual-voltage electric hair curling apparatus includes a having a handle and a heated barrel. A pair of positive temperature coefficient (PTC) heating elements are located in the barrel and are operable, respectively, at a low automotive vehicle voltage and a high domestic voltage. A switch in the handle permits energization of either heating element dependent upon the voltage of the available power supply and an overload fuse prevents damage to the low voltage heater should it be accidently energized from a high voltage supply. The curler is provided with a power cord terminating in a two-pronged plug receivable into a corresponding receptable on a portable vanity case adapted to be mounted by clips to the visor of an automotive vehicle. The vanity case has a mirror illuminated by electric luminaires on its front surface and a cord set terminating in a plug receivable in an automobile cigar lighter is connected to the receptable and luminaires.

Abstract: A power control system is disclosed for controlling the power output of a resistive heater element in response to operator selected power level settings by varying the rate at which a power pulse of constant duration is applied to the element. The system includes circuitry for generating a control signal representing a selected power output for the element, circuitry for identifying recurring patterns of a binary counter, the patterns recurring at different rates, and a logic arrangement for uniquely associating each of the patterns with a selected power setting. The binary counter and the power pulse control are synchronized with the power supply to trigger a power switching device at or near zero crossovers of the supply.