Abstract: The invention relates to an arrangement for fastening a plug into the edges of an opening of a case. In the arrangement of the inventions the plug includes, in connection therewith, fastening portions and grooves of varying depths for fastening the plug into the case opening. The arrangement also comprises a flexible element for arranging the plug into the case opening. The invention further relates to a plug to be arranged into the edges of an opening in the case. The plug includes, in connection therewith, fastening portions and grooves of varying depths for fastening the plug into the edges of the case opening, and a flexible element to be placed at the bottom of the deeper groove for arranging the plug into the case opening.

Abstract: An actuator comprises a gas exchange valve and an electromagnetic actuating drive, having at least one electromagnet which has a coil, having an armature, whose armature plate can move between a first bearing surface on the electromagnet and a second bearing surface. A device for controlling the actuator comprises a power output stage provided for driving the coil. The power output stage has an electrical energy store which is charged by the coil in a predetermined operating state. The control unit controls the power output stage in an operating state of rapid energization when a predetermined condition is met indicating the striking of the armature plate on the first bearing surface or an imminent fallback of the armature plate to a rest position, the energy stored in the electrical energy store being fed to the coil in the operating state of rapid energization.

Abstract: A method of controlling velocity of an armature of an electromagnetic actuator as the armature moves from a first position towards a second position is provided. The electromagnetic actuator includes a coil and a core at the second position. The coil generates a magnetic force to cause the armature to move towards and land at the second position. A control method is provided to ensure a near zero velocity landing of the armature in the second position while compensating for non-ideal external influences on the system.

Abstract: The present invention is a system for cyclically driving an electrical current through at least one non-linear (i.e., saturable) inductor in alternating directions so as to produce a substantially periodic current waveform, and for producing an output signal representative of the current waveform. The system includes at least one capacitive node electrically coupled between a voltage source and a system ground, for storing electrical energy provided by the voltages source. The energy stored within the system is transferred as electrical current in alternating directions through the inductor via a switching network and a controller for configuring the switching network. The controller allows current to flow in each direction until the inductor saturates.

Abstract: An apparatus (10) for altering the magnetic state of a permanent magnet comprises a coil inductor (26) for generating and applying an induced magnetic field to the permanent magnet. The coil inductor (26) is provided in circuit between two charge storage elements (20, 24). The apparatus also comprises a discharge control circuit (28) for transferring charge alternately in opposed directions between the storage elements (20, 24) though the coil inductor (26) to generate a series of alternating polarity magnetic field pulses (167, 191) of decreasing magnitude in the coil inductor (26) or to generate a single magnetic pulse of relatively high strength. The apparatus (10) can be operated as either a magnetising or demagnetising device and is capable of demagnetising a column of 200 or more magnets.

Abstract: An injector drive circuit capable of driving an injector of an internal combustion engine without using a DC-DC converter expensive. The injector drive circuit includes a power circuit for converting a voltage outputted from a magneto mounted on the engine into a DC voltage, a capacitor charged with a voltage accumulated in a voltage accumulator, a drive current feed circuit for applying a voltage across the capacitor to a solenoid coil to feed a drive current to the solenoid coil when it is fed with an injection command signal, and a holding current feed power supply section for feeding the solenoid coil with a holding current required for keeping a valve open after the drive current fed from the capacitor to the solenoid coil passes a peak value.

Abstract: There is proposed a circuit for operation of at least one relay having an OFF-position and an ON-position, wherein the relay assumes the OFF-position in the event of a component failure of any element of the circuit. In the ON-position of the relay a capacitor, the relay and a voltage source are switched in a predetermined cycle in such a way that in a first time interval of the cycle the voltage source delivers a current which flows through the relay and partially charges up the capacitor and that in a second time interval of the cycle the capacitor delivers the current which flows through the relay, with the capacitor being partially discharged again.

Abstract: A magnet device with double fixing positions for changing the magnetic circuit is provided, and includes an external housing whose inner edge is fitted with a coil The inside of the external housing includes a space for the axial movement of an iron core. The external housing and a positioning cover at the opening end of the housing are made of metal with excellent magnetic conductivity. The iron core is connected to a permanent magnet which is fixed at the inner side of the positioning cover. A drive circuit is provided whereby a positive impulse voltage will be output and the electrical energy is saved in a capacitor when the power is switched on. A discharge current is created to output a negative impulse voltage after the power is switched off, and the positive and the negative impulse voltages serve to make the coil change the direction of the magnetic force by the excitation process, so that a push force or a pull force on the iron core will be created for movement thereof.

Abstract: A control circuit for a latching solenoid incorporated in an electric door strike, the latching solenoid permitting the use of low power control pulses and the control circuit insuring reliable fail safe or fail secure operation with ready conversion between the two operating modes.

Abstract: A capacitive load drive is provided, which can perform faster and more efficient operation than an energy recovery circuit for effectively reducing ineffective energy of pulses applied to a capacitive load. An energy recovery circuit is connected to a first electrode of the capacitive load, to which pulses are applied. The energy recovery circuit comprises a coil and a capacitor connected in series for energy recovery, and a first and a second voltage clamp switches connected to the other terminal of the series circuit of the coil and the capacitor, the first voltage clamp switch being connected to a high voltage side terminal of the DC power supply, the second voltage clamp switch being connected to a low voltage side terminal of the DC power supply.

Abstract: A control device for an electromechanical circuit breaker device. The device includes a bistable type electromagnet to deliberately control power contacts and a monostable trip electromagnet to open the contacts in case of a fault. The bistable electromagnetic coil and the trip electromagnetic coil are placed in parallel with a capacitance. The control device includes a maintained control switch and an H bridge of two-way switches associated with the bistable coil. The control device acts on the bridge of switches and a trip switch opens the contacts depending on the current in the coils measured by sensors.

Abstract: In a circuit, switch (1) switches a current from a reference voltage terminal through an inductive element (3). The energy stored in the magnetic field associated with the inductive element when a current is flowing is transferred on interruption of the current either capacitively or inductively to an energy storage element (4). The stored energy is then returned to re-energize the inductive element (3) when the current flow is restored by the switch (1).

Abstract: A solenoid valve drive system includes a step-up circuit that produces a first high voltage by using a switching device to on/off control supply of current from a battery to a step-up coil and stores the first high voltage in a first capacitor as a high voltage for initial high-voltage driving of a solenoid valve, a second capacitor, and a discriminating circuit for discriminating the level of the charge voltage of the second capacitor. The second capacitor is charged by high voltage from the step-up circuit only when the charge voltage of the second capacitor has not reached a prescribed level. The system can efficiently produce two types of high voltages without enlarging circuit size.

Abstract: An actuation circuit for an electromechanical relay employs a microprocessor and a switching transistor to actuate a relay over a wide range of applied voltages. The switching transistor is connected in series with the actuator coil. A voltage sensing circuit is connected to one input of the microprocessor, which produces a pulse-width modulated actuator output to gate the switching transistor. The microprocessor is suitably programmed so as to produce a pulse width modulated signal actuator signal whose duty cycle is a function of applied voltage. The RMS current through the relay coil is sufficient to ensure good actuation, but does not overstress the coil. The relay is selected to have its rated actuation voltage at or below a lower end of the expected range of applied voltages. A relay actuation boost arrangement can include a transistor or an SUS (silicon unidirectional switch) or similar negative resistance device.

Abstract: A switching circuit for use in a subterranean probe for switching between to two modes of operation used to perform a survey of a well borehole. The switching circuit comprises a first voltage bias network which is biased to a predetermined overvoltage criterion; a second voltage bias network which is biased to a predetermined negative voltage criterion; a switch; and a negative voltage blocking diode for blocking the predetermined negative voltage criterion for allowing the first voltage bias network to fully realize the negative voltage criterion.

Abstract: A battery powered irrigation valve controller designed to conserve the life of both the low voltage battery source which operates the microprocessor circuitry as well as the high voltage battery source which operates the external valve solenoids. Energy leakage from the high voltage battery source is prevented by maintaining the primary capacitor in a discharged state and delaying the charging of this capacitor until just before it is to be discharged to the valve solenoid. Unnecessary depletion of the high voltage battery source is also accomplished by isolating this source from the primary capacitor immediately prior to discharge, thereby avoiding a draw of energy from the high voltage battery source itself during discharge. The low voltage battery source which powers the computer circuitry is conserved through the action of the microprocessor which does not run in a continuous current consuming mode, but which remains dormant except for periodic sampling.

Abstract: A device for deactivating magnetomechanical EAS markers includes a storage capacitor and a coil for generating a deactivation field. A bridge arrangement of four switches interconnects the coil with the storage capacitor and with circuit ground. The switches are controlled to apply a train of DC pulses to the coil such that the pulses have alternating polarities and decreasing amplitudes.

Abstract: A device and a process for activating at least two electromagnetic loads, in particular solenoid valves for controlling the amount of fuel to be injected. The load is connected to a voltage source through a bridge circuit. Furthermore, devices for stepping up the voltage are connected in parallel with the voltage source.

Abstract: An arrangement for driving actuator coils for two or more driven devices employs a microprocessor or similar controller and an actuator driver circuit. The actuator driver circuit controls two or more relay actuator coils from a single microprocessor output terminal. This output terminal can provide a high, low, or pulse output signal. An amplifier switching device, such as a transistor, whose base is coupled to the output terminal of the microprocessor, drives the first relay actuator coil as its load. A rectifying diode is connected to one end of a capacitor and thence through a negative resistance device to a second relay actuator coil or other driven device. The coil impedances are selected so that the second coil has a significantly higher impedance than the first coil. When output pulses appear at the microprocessor output terminal, the transistor switch pulses on and off, and thus energizes the first coil.

Abstract: Inductive energy from the coil of an electromagnetic actuator is stored in capacitive network at a relatively high voltage when the actuator is deenergized. When the actuator is energized, the capacitive network is coupled to the coil thereby releasing the stored energy at a high voltage to the coil.

Abstract: The control device has a drive circuit, in turn having a number of modular circuits--one for each inductor--activated selectively and receiving timing signals, and a common circuit connected to the modular circuits and cooperating with the activated modular circuit to supply the respective inductor. Each modular circuit has a first controlled switch connected between a first input terminal and a respective first output terminal, and a second controlled switch connected between the respective first output terminal and a storage capacitor; and the common circuit has a third controlled switch connected between the storage capacitor and a respective second output terminal, and cooperating with the second controlled switch to selectively transfer energy between the storage capacitor and the respective inductor.

Abstract: A solenoid control circuit is disclosed for providing the initial pull-in power to a magnetically-held solenoid and thereafter providing a release-pulse upon power loss to the circuit to release the solenoid. The solenoid control circuit has an AC input which is converted to a DC power supply. Power is supplied to an energy storage device after an initial time delay. After the time delay, the magnetic solenoid is tripped to its hold-in position. After being tripped, the magnetic solenoid is held in its hold-in position by the magnetic properties of the solenoid. Upon power interruption to the circuit, the solenoid is held in its tripped position for a desired period of time. After the time delay has expired, the energy storage device is discharged in an opposite direction through the magnetic solenoid, such that the magnetic solenoid is returned to its extended position.

Abstract: A control circuit for turning off or on direct current flowing through an inductive load (12) to ground uses a semiconductor switch (11), for example a MOSFET, having a first input terminal (D), a control terminal (G), and a second output terminal (S) to the load. A semiconductor freewheel diode (16) is coupled between the switch second terminal and ground, in parallel with the load. The freewheel diode has a current-conducting state and a current non-conducting state. A switching-off current source (19) is coupled between the second terminal and the control terminal; it reduces the magnitude of the switching control current (.+-.I.sub.GS) flowing into the control terminal of the MOSFET, as a function of voltage at the second terminal of the switch and the input to the freewheel diode. A minimum value (.+-.II.sub.GSmin) of the switching control current is reached when the voltage at the second terminal of the switch reaches ground potential.

Abstract: In accordance with the present invention there is provided an apparatus for deactivating electronic article surveillance tags comprising a deactivation coil, a capacitor, charging means for charging the capacitor to a predetermined level, and an electronic switch connected to the capacitor and the deactivation coil so that when the switch is open the capacitor can be charged by the charging means and when the switch is closed the capacitor can discharge through the deactivation coil.

Abstract: The present invention disclosed and claimed herein comprises a backup power system to supply current to an electromechanical actuator (50) to position a mechanical device (52) to a fail-safe position upon failure of a primary electric power source (12). A capacitor (40) is provided for storing energy. The capacitor (40) is charged by the primary electric power source (12). A relay device (35) is also provided for disconnecting the primary control signal upon failure of the primary electric power source (12) and connecting the capacitor (40) to the electromechanical actuator (50) to supply electric current to the electromechanical actuator (50) to position the mechanical device (52) to a fail-safe position. The relay device (35) comprises a transistor (32) which is kept turned off by the primary electric power source (12) and upon failure of the primary electric power source (12), turns on and energizes an electric relay coil (34).

Abstract: A device and a method are described for triggering an electromagnetic consumer, in particular a solenoid valve for controlling the fuel quantity to be injected. An energy-storing element is arranged between a half-bridge and a voltage source.

Abstract: The present invention is directed to a device intended to turn on loads and keep them on for a pre-established period of time and includes a remanence relay which includes a coil L, a movable contact 1, a fixed, normally opened contact 2b and a fixed, normally closed contact 2a. When a remote push switch S is pushed to its ON position, a first current flows through the coil L in a first direction to cause the movable contact 1 to move from engagement with the contact 2b to engagement with the contact 2a. As a result, power is applied to a load 5. When the switch S is opened, a timing circuit, which includes a capacitor C1, a resistor R3, an electric disruptive device D5 and a diode D4, is initiated which charges the capacitor C1. When the voltage of the capacitor C1 reaches the threshold voltage of the disruptive device D5, a second current opposite in direction to the first current flows through the coil L to cause the movable contact to move to the contact 2b and disconnect the load 5.

Abstract: An air conditioner having a fan motor brown-out control algorithm for increasing the air conditioner fan speed upon sensing a brown-out under-voltage condition is provided. The air conditioner has a power supply connected to an AC line voltage, a fan motor, a multispeed fan driven by the fan motor and means for sensing a brown-out condition of the AC line voltage. The sensing means is connected to the power supply and provides a signal indicative of a brown-out condition. The air conditioner also has means for increasing the speed of the fan in response to the sensed brown-out condition signal provided by the sensing means. In an embodiment, the air conditioner further has a microprocessor and related circuitry for adjusting the speed of the fan. In another embodiment, logic circuitry is provided instead of a microprocessor. A brown-out control algorithm for an appliance having a multispeed fan and components for operating the fan is also provided.

Abstract: An apparatus for making permanent magnet material magnetizes a body of material including a primary winding which has portions wound on a first core carrying current in a first direction creating a first field of flux and a secondary winding having portions wound on a second core wherein the secondary winding carries current in a second opposing direction to create a second field of flux. Since the currents are flowing in opposing directions, the secondary field of flux is directed to oppose the first field of flux. The result of this is that the magnetizer is capable of controlling the width of the pole to pole transition region for matching the stator geometry and thereby nearly eliminating cogging torque and reducing ripple torque.

Abstract: A circuit device for recovering energy from an inductive load is connected to a protection circuit for protecting a driver circuit from a charge contained in the inductive load. The inductive load is connected between a power supply line at one end and the driver circuit and protection circuit at another end. The circuit device has a charge accumulator, preferably a capacitor, connected to the protection circuit for accumulating charge from the inductive load. A control circuit monitors the level of charge in the capacitor. A switch, connected between the capacitor and the power supply line, permits the charge accumulated in the capacitor to discharge into the power supply line. The control circuit controls the switch so as to permit the intermittent discharge of the inductive load: the switch is opened to permit charge from the inductive load to accumulate in the capacitor; and, the switch is closed to permit the capacitor to discharge the accumulated charge to the power supply line.

Abstract: A magnetizing device for generating a high current magnetizing pulse includes a plurality of charge storage devices and a source of current connected by selector switches for charging selected ones of the charge storage devices to a predetermined voltage level. When the selected charge storage devices are charged the selector switches are opened and the selected charge storage devices are discharged through diode circuits coupled to a common SCR. In this way the current pulse does not flow through the selector switches. A peak current meter using a current transformer provides a display of the peak current of the magnetizing pulse.

Abstract: An electrically operated control device and system for an appliance and method of operating the same are provided, the system comprising a power source of alternating electrical current that has a repeating voltage wave cycle and a repeating current wave cycle, a load for using the electrical current to provide an output of the load for the appliance, a relay having normally open contacts and a coil for closing the contacts only when the coil is energized, an electrical circuit for interconnecting the power source to the load through the contacts only when the contacts are closed, and a control unit for causing the coil to close the contacts substantially at a certain point on the voltage wave cycle each time the relay coil closes the contacts from the open condition thereof whereby the current flow through the contacts at each closing thereof is at substantially a desired level thereof.

Abstract: A dot matrix printer having a print head having a plurality of print solenoids. The print head is carried on a print head carriage driven by a carriage drive arrangement. A print timing means supplies a sequence of print timing pulses as said print head traverses a print medium. A power supply supplies a print voltage to the print solenoids in the print head. A drive pulse circuit responds to each of said print timing pulses for producing a solenoid enable pulse of a duration which varies inversely with the magnitude of said print voltage. The drive pulse circuit utilizes a dual slope integration with a first period integrating a fixed voltage for a fixed time and a second period integrating the varying print voltage for a time which varies with the magnitude of the voltage and provides automatic adjustment of the total print timing signal.

Abstract: A flashing locator switch control includes an audible alert circuit with the switch and flasher to provide assurance to the user that the outside light is operating to flash on and off and by which to test the outside light at any time day or night.

Abstract: An electrically operated control device and system for an appliance and method of operating the same are provided, the system comprising a power source of alternating electrical current that has a repeating voltage wave cycle and a repeating current wave cycle, a load for using the electrical current to provide an output of the load for the appliance, a relay having normally open contacts and a coil for closing the contacts only when the coil is energized, an electrical circuit for interconnecting the power source to the load through the contacts only when the contacts are closed, and a control unit for causing the coil to close the contacts substantially at a certain point on the voltage wave cycle each time the relay coil closes the contacts from the open condition thereof whereby the current flow through the contacts at each closing thereof is at substantially a desired level thereof.

Abstract: A device including a circuit for energizing a latching solenoid from an AC power source which separates the latching solenoid from the AC power circuit. The device provides for reliable operation of the latching solenoid, and may be separated from the AC power source by several thousand feet of high gauge (lower cost) wire. The device operates on low AC voltage and current making it highly energy efficient.

Abstract: A circuit arrangement for reversing a magnetic field, in which an oscillator has a coil connected in parallel with a capacitor. First and second diodes are connected oppositely-poled in a series circuit, which is connected in parallel with the coil and capacitor of said oscillator. A first electronic controlled switch is connected in parallel with the first diode for bypassing this diode, whereas a second electronic controlled switch is connected in parallel with the second diode for bypassing thereof. Energy is supplied to the oscillator whenever the capacitor discharges. The junction of the series connected diodes is connected to the junction of the series-connected switches.

Abstract: A power management circuit for operating a magnetic repulsion punch comprising a storage capacitor arranged to be connected in parallel with an inductive load serving as an operating coil of the magnetic repulsion punch, a means for selectively and temporarily coupling the inductive load to the storage capacitor for forming a resonant circuit, and a means for charging the storage capacitor after each operation.

Abstract: At magneto-optical recording- and reproducing equipment is provided an electromagnet, in order to be able to remagnetize the magneto-optical layer of a magneto-optical record in dependence of Bits to be stored.In order to achieve a fast and safe reversal of the magnetic field, two series circuits consisting of a first and a second diode (D1, D2), a series circuit consisting of a third and a fourth diode (D3, D4) and a DC-voltage source (U) are connected in parallel to each other. The common terminal (A) of the first and second diode (D1, D2) are connected via a coil (L) with the common terminal (B) of the third and fourth diode (D3, D4). The second diode (D2) is bypassed by a first variable switch (S1) and the fourth diode (D4) is bypassed by a second variable switch (S2).

Abstract: An electrically operated control device and system for an appliance and method of operating the same are provided, the system comprising a power source of alternating electrical current that has a repeating voltage wave cycle and a repeating current wave cycle, a load for using the electrical current to provide an output of the load for the appliance, a relay having normally open contacts and a coil for closing the contacts only when the coil is energized, an electrical circuit for interconnecting the power source to the load through the contacts only when the contacts are closed, and a control unit for causing the coil to close the contacts substantially at a certain point on the voltage wave cycle each time the relay coil closes the contacts from the open condition thereof whereby the current flow through the contacts at each closing thereof is at substantially a desired level thereof.

Abstract: A shell-form transformer for charging an energy storage device contained in a battery powered impact device. The primary and secondary windings of the transformer are wound in a predetermined manner around the center leg of a core which has an air gap therein. The gap increases the reluctance of the center leg which decreases the flow of magnetic flux through the core which, in turn, enables the current applied to the transformer primary to be increased without causing the core to be saturated. As a result, the current applied to the transformer primary can be increased, thereby increasing the output voltage supplied from the transformer secondary which, in turn, enables rapid charging of the energy storage device.

Abstract: Solid state control circuitry for driving an electromagnetic armature of a battery operated electric stapler. The armature is activated by a trigger signal generated by a trigger switch which discharges an energy storage device through the armature. Energy is rapidly replenished in the energy storage device following its discharge; but if a subsequent trigger signal is not forthcoming, the control circuit reverts to a quiescent state, thereby reducing power consumption.

Abstract: A relay driving circuit for a latch-in type magnetic relay having an excitation coil, generating a set current and a reset current of opposite polarity for the coil. A capacitor is provided between the input terminals of the circuit in series with the coil. A set switch is connected in series with the coil and the capacitor, and a reset switch is connected across the series combination. An input voltage level detector is provided to make the set switch conductive, thereby applying the input voltage to the excitation coil and the capacitor to provide the set current. As the input voltage decreases below the trigger level, the detector makes the reset switch conductive to allow the capacitor to discharge current in the opposite direction through the excitation coil.

Abstract: The invention relates to an apparatus for controlling the triggering sequence in capacitive ignition systems for internal combustion engines. The induction achieved by a flywheel magneto usually results in three voltage wave halves, of which two (A,B) have one polarity and an intermediate one (C) has an opposite polarity. In the present case, the first voltage halfwave (A) is used for triggering voltage and the subsequent halfwave with opposite polarity (C) for the charging voltage. The subsequent last voltage halfwave is suppressed (B") to a level below the triggering level. This is achieved by arranging an inhibiting circuit (11-15) for the conventional triggering circuit (8,9,10) by charging (11) a further capacitor (12) during the charging phase itself, the capacitor (12) maintaining control voltage for a further thyristor (15) or triac, which is arranged to short-circuit the triggering voltage.

Abstract: A power supply incorporating a fault detection circuit controlling a circuit breaker is described. The power supply is isolated from relatively large applied DC voltages. This isolation is provided by a coupling capacitor in each of the line leads. The tripping energy for the circuit breaker can be provided either directly from the full wave rectifier output, or directly from the line lead or leads. In the case of the former, a reservoir capacitor may be used for storage of charge for tripping of the circuit breaker.

Abstract: A valve driving apparatus includes a permanent magnet connectd to a suction/exhaust valve and an electromagnet secured to the engine body, and is adapted to drive the valve by attractive and repulsive electromagnetic forces which act between the electromagnet and the permanent magnet. The electromagnet ordinarily is supplied with electric power from a battery. However, if a strong electromagnetic force is to be applied to the suction/exhaust valve, the electromagnet is supplied with charge from a capacitor charged beforehand by the battery. Control is exercised to increase or decrease, in dependence upon the engine rpm or load, the amount by which the electromagnet is energized by the battery and the amount by which the capacitor is charged.

Abstract: A bistable electromechanical transducer is disclosed having an armature reciprocable between first and second positions, a permanent magnet latching arrangement for maintaining the armature in the respective positions, and an electromagnetic repulsion arrangement operable when energized to dislodge the armature from the position in which the armature was maintained and causing it to move to the other of the positions. In a preferred embodiment, the transducer takes the form of an electronically controllable valve mechanism for use in an internal combustion engine and has an engine valve with an elongated valve stem along with the electromagnetic repulsion arrangement for causing the valve to move in the direction of stem elongation between valve-open and valve-closed positions.

Abstract: An electrical circuit is employed for receiving current from a small battery and converting it into a large intermittent force which will move a heavy load. In the example shown the load is a clock spring which is wound in small increments by the large intermittent force. A capacitor is charged by the battery. The battery and capacitor, therefore, temporarily have a higher output current than the battery alone. The output of the battery and capacitor is applied to a solenoid for attracting an armature and providing the large force. The resulting movement of the armature opens the circuit to the solenoid but the solenoid remains energized temporarily since a small capacitor is across it. When the armature returns to its normal off position it reenergizes the solenoid. The resulting on and off operation of the solenoid continues until the clock spring is fully wound.

Abstract: A food compartment (I) and a freezer compartment (II) are both cooled by an evaporator coil mounted in the freezer compartment. An air damper assembly selectively allows cold air to flow from the freezer compartment to the food compartment to maintain a selected temperature in the food compartment. The air damper assembly includes a damper door (101) which is slidably mounted to a housing (110) to provide sufficient motive force to drive the damper door to one of the open and closed positions. The damper door is frictionally retained in the selected one of the opened and closed positions until a like momentary electrical pulse is applied to the other coil to drive the damper door to the other position. Optionally, momentary pulses may be applied intermittently to the same coil to assure that the door remains in the selected opened or closed position.

Abstract: A relay driver circuit, suitable for controlling a bistable relay, includes .[.a storage device which is charged to a first voltage level by a low current flow voltage source..]. .Iadd.a transformer which handles both an information signal and a control signal and a storage device. The control signal is provided by a low current low voltage source. .Iaddend.A first switching circuit couples the storage device to the bistable relay when the first voltage level exceeds a predetermined value. The charge on the storage device is dumped into the relay and forces it into a first state (set). A second switching circuit is coupled to sense the voltage on the storage device and the voltage on the low voltage source. When the voltage on the low voltage source falls below the voltage on the storage device, current flows from the storage device and forces the relay into a second state (reset). The reset time is within 100 .mu.s.