Abstract: A control circuit for a sauna compartment has an electrical heater therein connected to a control circuit. The control circuit allows a high voltage to flow through a first heating circuit to permit ambient air in the compartment to reach a first high temperature, at which time voltage is provided to the heater only through the second heating circuit and thence to the heater so that the ambient air in the compartment will maintain said first high temperature to prevent a person in the sauna compartment from feeling immediately chilled when the first high temperature is reached and voltage through the first heating circuit ceases to move to the heater.

Abstract: A steam sterilization apparatus (10) includes an electronic control system having a main control circuit (C) including a central processing unit (68), an input device (36), and output devices (24,28) provided on a single circuit board (22) which is attached to a front bezel (16) of the sterilizer (10). The sterilizer (10) includes a flash steam generator (56). The main control circuit (C) implements an over-temperature feedback circuit (160) that disconnects the heating elements (162) in the steam generator (56) from electrical power when an over-temperature condition is detected. Isolated feedback is provided to the central processing unit (68) confirming the heating element disconnection operation. The control system includes error switches (82, 86, 88) that detect various error conditions. Upon an error condition being detected, the steam supply to the steam sterilization chamber (12) and/or to the pressurized steam seal (42) of the apparatus (10) is halted.

Abstract: Apparatus for control of cooking foods temperature by sensing their temperature with thermistors, which form part of a first electrical circuit that induces a magnetic flux in an electromagnet, a second electrical circuit that induces, in the electromagnet, a flux of opposite direction to the former, the resultant flux (larger flux minus smaller flux) generating a magnetic pull on the electromagnet's armature.The armature is linked to an on/off switch that forms part of a third electrical circuit that contains an alarm.Spring actuated forces on the armature oppose the magnetic pull. Increase in food temperature brings an increase of current intensity in the first circuit, which causes the magnetic pull to decrease.At the pre-selected controlled temperature of the food, the magnetic pull is slightly smaller than the opposed springs forces. At this point the armature separates from the core, putting the third circuit's switch on and activating the alarm.

Abstract: This is a method of controlling an electric heater of a catalytic converter. An electric heater is powered by two separate batteries. There are an electronic control unit, a power switch, and an isolating switch providing logic control to the electric heater.

Abstract: A control system for use with a boiler and associated burner. In one embodiment, the system comprises a first control circuit for producing a signal having alternating first and second states, the first state activating the burner and having a first predetermined duration, the second state deactivating the burner and having a second predetermined duration that defines a time period that allows foam and surging fluid in the boiler to settle, and a relay responsive to the first control circuit signal and adapted for connection to a power source and the burner, when the first control circuit signal has the first state, the relay connects the power source to the burner to activate the burner, when the first control circuit signal has the second state, the relay disconnects the power source from the burner to deactivate the burner.

Abstract: A toaster control circuit is disclosed for correcting for toaster cavity temperature variations that occur as a function of the time between toaster heating cycles. This disclosed circuit produces the same toast color during consecutive cycles, regardless of variations in the interval between heating cycles.

Abstract: The disclosure involves a countertop distiller for home use. Such distiller is of the type including a condensing coil and an electrically-powered water heater. A method for controlling power flow to the heater includes the steps of activating a timer circuit to energize the heater, increasing the temperature of the coil and bypassing the timer circuit when the coil temperature increases to a predetermined value. The heater is de-energized when the water in the raw water container is substantially depleted and the heater temperature increases to a predetermined value because of such depletion. A new electrical circuit for a countertop distiller is also disclosed.

Abstract: In a toaster, a system is constructed to vary the duration of the toasting cycle. An RC network provides an oscillating signal to a counter, which upon the required number of oscillations being counted, triggers a transistor switch. The switch energizes the main solenoid switch which in turn deactivates the heating elements of the toaster. The RC network of the system comprises a variable resistor which may be manually operated, a heat sensitive resistor, and a light sensitive resistor.

Abstract: The temperature of each heating element among a plurality of heating elements is regulated by opening and closing a relay associated with each heating element in response to the monitored temperature of each heating element. The voltage across all of the relays is interrupted simultaneously at predetermined intervals, and each relay is opened or closed only when the voltage is interrupted. This permits the use of relays having lower current ratings and also extends relay life.

Abstract: In an engine exhaust system including a DC power source, an apparatus and method for electrically heating a catalyst, the apparatus comprising a multi-phase AC alternator in electrically operable relation to the DC power source, the AC alternator rectifying the AC to DC by a diode rectifier bridge. A device for switching power supplied from the multi-phase AC alternator to the battery to the electrically heated catalyst, the relay device in electrically operable relation with the multi-phase AC alternator. An electrically heated catalyst in electrically operable relation with the switching device is also provided, the catalytic converter including a catalyst for purifying exhaust gases of the engine and a heating element for bringing the catalytic converter expediently within peak operating temperature. The invention further includes a device for energizing and de-energizing the switching device, the energizing and de-energizing device in electrically operable relation with the switching device.

Abstract: A spa control circuit is provided for regulating a water circulation and heating system in a spa or hot tub or the like. The control circuit comprises a thermostat circuit and a high temperature limit circuit, both of which receive a temperature signal from a common temperature sensor. A safety circuit responds to sensor failure to prevent operation of the circulation/heating system. A latching relay ensures system reset in the same operational state following a power outage. An arc suppression circuit substantially prevents arc damage to relay contacts subjected to frequent opening and closing in response to on-off cycling of the thermostat circuit. In a preferred form, the control circuit components are mounted within a compact housing having a heat transfer member in heat exchange relation with circulating spa water, whereby the spa water is used to prevent overheating of the control circuit components.

Abstract: A control system for dual oven resistance heaters (BAKE, BROIL) has opposite sides of each heater connected to a common side of one of a pair of SPDT switching relays such that no current flows to the heaters when both relays are in a common state of energization/de-energization. A microcomputer receives a signal from the oven temperature sensing and signals separate switching devices to selectively energize/de-energize one of the relays to switch on the desired heater. Separate comparators also receive the temperature sensor signal; and, in the event of failure of the microcomputer or switching devices with a heater "ON", the comparator is operative to bring the relays to a common state, preventing current flow to either heater.

Abstract: A two terminal line voltage thermostat includes a switch which connects one side of the line voltage to a heater load (that it drives) such as a baseboard heater with the other side of the heater being connected to the other side of the line. Common full wave rectifier components drives both a relay coil and the remaining electronics of the thermostat. In addition, an arc suppressing triac across the switch while necessarily connected to the primary side of a transformer is directly driven from the secondary which is ungrounded; the primary also provides choking for the triac.

Abstract: An electric toaster that enables power to be disconnected from the heating elements upon completion of a toasting cycle regardless of the position of the main product supporting the carriage in the toasting compartment. The toaster has an electromagnetic latch and an auxiliary member carried by the main carriage which is movable relative to the main carriage. The auxiliary member is urged by biasing member to move in a direction away from the electromagnetic latch but able to be held thereby when the latch is activated. The auxiliary member also is arranged to close main power supply contacts to supply power to the heating elements when the auxiliary member is held by the latch, but to open said main supply contacts when the auxiliary member moves away from the latching means under action of the biasing member. The toaster may also include a sensor to sense abnormal conditions in the toaster to disconnect power from the heating elements when such abnormal conditions occur.

Abstract: When a carriage of the toaster is in a lower position, a switch (21) is closed and power passes through a bridge rectifier circuit (22) to an integrated circuit (19), which, for the normal cooking operation, switches SCR (20) off so that a relay (7) is energised, switching switches (8) and (9) on to energise heating elements (2) and (3). Power is also supplied to a latch (27) to hold the carriage in the lower position. If, however, a fault detection is input from a residual core balance (12) to the integrated circuit (19), SCR (20) is switched on so that power from bridge rectifier (22) is shorted. This causes relay (7) and latch (27) to be de-energised so that the heating elements (2) and (3) are turned off and the carriage is returned to the upper position, causing switch (21) to open.

Abstract: A fail-safe control system for operating a power relay to energize an electrical load such as a resistive heating element in a cooking apparatus includes first and second driving transistors connected in series with the control winding of the power relay and a source of power. A logic circuit, such as a microcomputer, produces pulses having specified characteristics at a single output port in order to energize the control winding. A circuit interconnecting the output port of the logic circuit with the driving transistors includes a first branch connected with the first transistor and a second branch connected with the second transistor. The first branch of the circuit includes an operational amplifier connected by a capacitor with the logic circuit output port in a manner that the first branch will drive the first transistor for a sufficiently long period of time initially in order to energize the relay control winding and cause the power relay to pull in.

Abstract: A device is provided for detecting the presence of a food cooking container (9) placed on a cooking hob (1), in particular of glass ceramic, provided with at least one heater element such as an electrical resistance element (2, 40, 41, 42), a gas burner (30), a halogen lamp or the like includes at least two plates (11, 12) of electrically conducting material associated with the hob (1) and connected to an electrical circuit (13), and being of opposite polarities, said plates acting as plates of a capacitor, i.e. forming a capacitive sensor the capacitance of which changes when the food container is placed on the hob (1) in a position corresponding with said plates (11, 12), the change in capacity of said capacitor being sensed by the electrical circuit (13), which therefore detects the presence of said container (9), to generate a control signal as a result of such detection. This signal is fed to indicator means (20) to indicate which heater element has to be operated to heat the container.

Abstract: An air conditioner has a refrigeration system with a compressor, a motor for air-circulating fans, indoor and outdoor heat exchangers and a four-way valve connected through refrigerant conduits such that it can be operated selectably both for cooling and for heating. An electric heater is also provided for heating. An electrical circuit for the air conditioner has a series connection of (1) a first temperature switch which opens when the temperature of the motor becomes too high, (2) a thermostat of an ordinary kind which places its connector piece in an open or closed position by comparing room temperature with a user-set temperature level, (3) a relay which controls the switching of the compressor of the air conditioner on and off, and (4) a second temperature switch which opens when the temperature of the electric heater becomes too high.

Abstract: A controller 3a for a Diesel engine, supplied with source voltage from a DC voltage source (battery) 1 and controlling the current supply to the glow plug 4a via a glow relay 6, includes, in addition to a microcomputer 13 and a reset circuit 14, etc., a source voltage step-up circuit 2. The source voltage step-up circuit 2 includes a source voltage detection circuit, and when the source voltage drops below a predetermined normal level, the circuit steps it up (i.e., raises it) to above the normal level. Thus, even when the engine is started at a low temperature and the source voltage falls below the normal level during the cranking of the engine, the glow plug 4a can be heated to a temperature at which the engine can be started.

Abstract: An electric toaster includes a housing having at least one heating element mounted therein. A source of electric power is selectively connected to the heating element for energization thereof. A carriage is mounted in the housing for supporting a food product to be toasted and is movable between upper non-toasting and lower toasting positions. An electrically operated latch mechanism holds the carriage in its toasting position. A temperature sensing switch is electrically connected to the latch mechanism for releasing the mechanism and returning the carriage to its non-toasting position when the temperature of the food has reached a predetermined level. A time delay mechanism is electrically connected to the temperature sensing switch for disabling the switch during an initial period of time at the start of each toasting cycle when the carriage is moved to its toasting position.

Abstract: Electrical power for an electrically heated vehicle windshield is controlled by an arrangement utilizing a modified alternator coupled to the windshield heater via an autotransformer. In a high power mode, the vehicle battery is coupled to a center tap of the alternator, while in a normal power mode the vehicle battery is coupled to a conventional rectified output of the alternator. A microprocessor controlled silicon controlled rectifier bridge provides direct current to the windshield heater element by rectifying the output of the autotransformer. Additionally, a current sensor coupled to the heater element is utilized by the microprocessor to determine the electrical resistance of the heater element in order to take required diagnostic measures.

Abstract: A relay control for a cooking appliance having a heating element includes a sensor for detecting the occurrence of an arc upon a change of state of a relay coupled between the heating element and a power supply. Upon detecting an arc, the sensor provides a timing signal which is coupled to a microprocessor that controls the energization and deenergization of the relay. The microprocessor is responsive to the timing signal from the sensor to determine the time delay between the last energization/deenergization of the relay and the changing of the relay's state. From the time delay, the microprocessor determines a delay constant. Subsequently, the microprocessor energizes the relay at a time after the detection of a zero crossover point of the power supply signal, wherein the time is equal to the determined delay constant to cause the relay to change state at or slightly before a zero crossover point of the power supply signal.

Abstract: A relay control for a cooking appliance having a heating element includes a sensor for detecting the occurrence of an arc upon a change of state of a relay coupled between the heating element and a power supply. Upon detecting an arc, the sensor provides a timing signal which is coupled to a microprocessor that controls the energization and deenergization of the relay. The microprocessor is responsive to the timing signal from the sensor to determine the time delay between the last energization/deenergization of the relay and the changing of the relay's state. From the time delay, the microprocessor determines a delay constant. Subsequently, the microprocessor energizes the relay at a time after the detection of a zero crossover point of the power supply signal, wherein the time is equal to the determined delay constant to cause the relay to change state at or slightly before a zero crossover point of the power supply signal.

Abstract: A power-off control circuit for a household appliance, including a manually operating momentary switch having conductive and non-conductive states. The switch is connected to a source of electric power so when the switch is momentarily manually operated into the conductive state, power flows into the power-off control circuit. There is a power regulator connected to the manually operating switch for receiving the power during the conductive state and for converting the received power into a voltage. A timer is connected to the power regulator and when activated, initiates a predetermined time period in which the household appliance operates. The circuit also includes a relay connected to the timer and the source of electrical power so as to be in parallel with the manually operating switch. The relay operates in a conductive and non-conductive state and is in the non-conductive state until receiving a signal from the timer at which time the relay changes to the conductive state.

Abstract: A heating apparatus including a heating member for heating a subject, a temperature detector for detecting a temperature of the subject an energizing control element that is electrically connected to the temperature detector so that current conduction to the heating member at a the time when the temperature detector is actuated to operate after the subject to be heated and a switch element for disconnecting the temperature detector to the energizing control element in response to the actuation of the energizing control element. The heating apparatus is appropriate for use in a vacuum coffee maker.

Abstract: A control device for controlling the operation of an object of cooking such as a stove or the like. The presence of a user in the area of the stove is detected. When the user is present, the stove operation is enabled. After the user has been absent from the area for a first predetermined time, the stove is temporarily disabled, an again enabled when the user enters the area. If the user is absent from the area of the stove for a second predetermined time, the stove is permanently disabled, so that it cannot again be enabled until manually reset.

Abstract: Cooker automatically controlling the heating process when bringing a food material to the boil on an electric hotplate and preventing it from boiling over at the end of the heating process. At the beginning of the heating process the power supplied to an electric hotplate can be set to a constant value which can be selected. A microprocessor continuously determines the rise in the temperature of the base of the pan as a function of time. At a pan-base temperature above about 70.degree. C. the actual value of the rise in temperature is compared with a present desired value and when deviations occur the heating power is switched over so as to approximate the actual value of the rise in temperature to the desired value. At a pan-base temperature above about 90.degree. C. a bending point in the temperature rise of the pan base is reached after which the heating power is switched off.

Abstract: An electric heating unit for detachable mounting in a motor vehicle includes an outer casing adapted to be fixedly secured in the vehicle and having a recessed portion for removably receiving an electrical heating appliance, such as a water heating pot, provided therein with an electric heating element and a temperature sensor capable of producing switching signals indicative of the temperature of the appliance. A power control switch and switch actuator responsive to the temperature sensor are located in the outer casing at a location remote and shielded from the heating element when the appliance is seated in the recessed portion. The power switch is connected in series with the heating element in a power supply circuit by mating detachable connectors on the outer casing and heating appliance. The temperature sensor and switch actuator are connected in series through the detachable mating connectors in a control circuit in parallel with the power supply circuit.

Abstract: A portable electric hair dryer includes an electric heater and blower forming a load circuit energized from a pair of power feeder lines connected to a source of AC power. A zero phase-sequence current transformer is electrically coupled to the power feed lines between the connection thereof to the power source and the load circuit to serve as a current leakage detector. An electricaly conductive heater enclosure disposed within the housing of the hair dryer receives the heater and is electrically isolated from the power feed line serving as the hot line. The heater enclosure is electrically connected to the power feeder line serving as the neutral line by a ground wire extending between the heater enclosure and the point at which the zero phase-sequencing transformer is coupled to the power feeder lines to define a leakage current path between the hot line and the heater enclosure should the hair dryer be dropped in water.

Abstract: A control apparatus for diesel engines controls the energization of glow plugs each of which is disposed in a cylinder of a diesel engine and heated by an energizing current flowing therethrough. When fuel supply to the engine is resumed after the engine temperature has fallen due to the interruption of fuel supply during a decelerating operation of the engine and further when fuel supply is enriched during an accelerating operation of the engine while it is cold, the control apparatus controls the energization of the glow plugs, thereby promoting the combustion of the engine and improving the combustion efficiency of the engine.

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: A beverage warmer assembly comprising a support unit having an electrically heated surface on which a beverage-container unit such as a cup may rest, the container unit and the support unit having magnetically coacting elements so mounted to the respective units that a switch is (a) connected for electrical heating of the surface for one orientational relation of container-unit seating on the surface and (b) is inoperative for a different orientational relation of container-unit seating on the surface.

Abstract: An apparatus for controlling the preheating of a diesel engine in which a preheating plug is rapidly brought to starting temperature so that the engine be substantially instantaneously started. Each preheating plug in each of the cylinders of the engine has a heater body having a resistance which varies with temperature changes but which is sufficiently small that the heater body would melt if a predetermined rated voltage were continuously applied thereto. When the starter switch of the engine is in the engine accessory position, so long as the detected temperature of the heater body is below an upper preheating temperature, the rated voltage is applied directly to the heater body. When the temperature of the heater body reaches the upper temperature, the heater body is disconnected from the battery. In the engine starting position of the starter switch, the quick heating circuit is disconnected and the heater body is coupled to the battery through a stabilizer resistor.

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 current shunt in the power supply to an electric furnace generates a signal voltage proportional to furnace current. A voltage rate comparator senses a high change rate of signal level corresponding to arcs occurring in the furnace and the comparator output pulse is fed to a preset counter. The counter is reset periodically. If a predetermined number of pulses are registered by the counter within a preset time interval, the counter output will de-energize an output relay which turns the power supply off and energizes a warning signal.

Abstract: An apparatus and method of drying a transformer by applying current to a winding thereof in a controlled fashion. Alternating with periods of applying the current to the winding, the electrical resistance of the winding is periodically measured using a bridge circuit. The application of the current is controlled, dependent on the results of the resistance measurements, to discontinue the application of current when the measured resistance is equal to or greater than a preset resistance. The current application is resumed when the measured resistance falls below the preset resistance. In a preferred form insulation resistance is tested by measuring leakage current after each measurement of winding resistance and when leakage resistance reaches an acceptable level the apparatus is shut down.

Abstract: A parallel circuit of an ordinary resistor exhibiting an ordinary resistance characteristic and a starting resistor abruptly increasing its resistance at a certain temperature is inserted between glow plugs in a Diesel engine and a battery. The resistance of the starting resistor is smaller than that of the ordinary resistor at a normal temperature. The resistance of the starting resistor becomes larger than that of the ordinary resistor when a large amount of current flows through the starting resistor. Therefore, current flows from the battery to the glow plugs mainly through the starting resistor at first, and then it flows mainly through the ordinary resistor. The ordinary resistor is disposed in an intake air passage of the engine.

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: A control circuit for a glow plug assembly serving as an engine preheating apparatus is designed so as to effect a temperature control in conformity with the specified position established by selective operation of a key switch having three switching positions, i.e., OFF, ON and START positions. The control circuit comprises a first switch connected between the glow plug assembly and a power source, and a series circuit comprising a second switch connected parallel with the first switch and a resistor.

Abstract: A control circuit for supplying power to the heater of an electrically heatable windshield of an automotive vehicle while simultaneously providing the requisite current for the standard electrical system of the vehicle includes a resistive heating element connected in series between the vehicle alternator output and the high voltage terminal of the vehicle battery, so that current conducted through the heating element is supplied to both the battery and the load circuit. A control circuit, responsive to the alternator output voltage and the battery voltage, controls a voltage regulator to regulate the alternator output voltage within a first narrow band corresponding to the rated battery voltage and within a second narrow band corresponding to a given power rating for the heater.

Abstract: A control circuit is disclosed suitable for use with a toaster or other food browning device which utilizes a radiant energy source to brown food. A light sensitive variable resistor, or photocell, is optically coupled to light reflected from the food being browned in the device. A voltage generated by a voltage divider including the light sensitive resistor therein is compared with a preselectable voltage generated by a second voltage divider to determine whether the heat source should be turned on or off. Suitable solid state control circuitry is provided to ensure that a start-up delay is provided at the beginning of each browning cycle and to reset the circuit for future operation when the desired browning of the food is achieved.

Abstract: The invention relates to a safety control shut-off device for the heating element of a cooking stove. In one embodiment of this safety device, a burner plate of the stove is provided with several declining U-shaped grooves for collecting any spillage or overflow of water from the cooking operations. Water drops collected in the declining grooves are led through a discharge outlet, at the lowest portion of the grooves, and into a water drop detector located beneath the outlet, to complete an electrical circuit, which in turn will actuate and sound an alarm and will also actuate means for disconnecting the fuel source of the plate burner.