Abstract: An electromagnetic contactor or controller is taught in which the voltage which is impressed across the electromagnetic armature accelerating coil is compared by a microprocess against a menu of memory stored voltages with related delay angles. The delay angles are utilized to alter the conduction interval of a triac or similar gated device which is connected in series circuit relationship with the coil in question. During an ACCELERATION interval a number of consecutive full-wave rectified half-cycles of voltage pulses are phase angle or delay angle controlled so that the amount of energy provided to the moving armature of the contactor is approximately sufficient to cause the armature to abut a fixed magnetic member. Furthermore, there is provided a separate memory menu for mid-flight adjustment of the armature to compensate for unknown variations to fine tune the closing operation. This latter correction is known as COAST.

Abstract: A circuit and method for actuation of a gas intake or exhaust valve which is electromagnetically held in its opened and closed positions by an actuator assembly having a ferromagnetic element attractable by actuating solenoids. Control of the holding current flow through the solenoid coil is provided by a relaxation circuit element, and the excitation current is directly monitored and measured. Upon deexcitation of the coil and relaxation circuit-element activation, the decay current is not measured but is instead simulated. The relaxation circuit is supplied with pulsed current during the stationary phase of the valve, the current being measured in the pulse cycle during current supply, and is turned off upon exceeding a ceiling value. After the decay current has reached a threshold value, the current is turned on and permitted to rise momentarily. It is thereafter cycled off and on between an I.sub.1 and I.sub.2 value which is only about 10-20% of I.sub.max, the capture current.

Abstract: A method and apparatus for driving an electromagnetic device includes two coils which selectively attract and repel a moving body. In order to allow a quick switching of the moving body between being attracted by one coil and the other, the current through the coil which is not holding the moving body in its magnetic field can be made to be a level higher than the current to the coil which is holding the body in its magnetic field. By reducing the current to the coil that is holding the body, the body can be rapidly switched to be within the magnetic field of the other coil. In addition, the currents to the respective coils can be increased before this switching occurs. Structure can also be provided across the coils to quicken the time it takes for the magnetic field to dissipate.

Abstract: A device for driving an electromagnet from a direct current source includes first and second circuits which are coupled in parallel to each other, and in parallel to a direct current source. The first circuit has a first switch, a solenoid coil, and a second switch all in series with one another. The second circuit has a third switch, a storage coil, and a fourth switch all in series with one another. A third circuit is provided which has a diode which is arranged to provide a current path from a junction between the storage coil and the fourth switch, to a junction between the first switch and the solenoid coil. In operation, during solenoid standby, the choke coil is caused to store electromagnetic energy. When the solenoid coil is energized, the switches are operated such that the energy stored in the storage coil is caused to quickly charge into the solenoid coil. The solenoid coil is maintained energized by operating the first switch in a chopper mode.

Abstract: The invention relates to a device adapted to reliably operate solenoids controlling valves at long distances from a central control station thereby enabling the use of light weight electrical cable between the control station and the solenoid, the device including a capacitor and a switching arrangement enabling current stored by the capacitor to be supplied to the solenoid to activate the solenoid, power being supplied to the capacitor from the central control station.

Abstract: A solenoid driver control circuit for use with solenoids, the circuit including a current sense unit (12) for providing a current sense signal and a solenoid drive unit (13) for selectively allowing current to flow through the solenoid (11) from a power source (14). The circuit also includes a threshold comparator unit (17) for comparing threshold signals with the current sense signal and for providing an output signal that can control the solenoid drive unit (13), a minimum threshold unit (18) for providing a minimum threshold, a maximum threshold unit (19) for initially providing a maximum threshold until a peak current flow through the solenoid (11) has been established, a first timing unit (21) to periodically provide increased threshold signals for specified durations of time, and a second timing unit (41) for initially providing an increased minimum threshold signal at the outset of a control cycle.

Abstract: A current controlling device comprises an input circuit for receiving a driving signal, means for supplying a first reference voltage or a second reference voltage lower than the first reference voltage, a detecting resistor for detecting current flowing through an electromagnetic winding, and means for supplying the electromagnetic winding with a starting current and a holding current. The starting current initially rises then is maintained at a constant value based upon the detected voltage of the detecting resistor and the first reference voltage. The second reference voltage is supplied in place of the first reference voltage after a predetermined period of time and continues to be supplied until the driving signal ends. The holding current is maintained at a constant value lower than said constant value of the starting current based upon the detected voltage and the second reference voltage. Both the first and second reference voltages are controlled to be constant voltages.

Abstract: An improved dot matrix actuator is provided which includes a magnetic circuit formed of a yoke assembly and a pivotal armature. The armature is pivotally supported with respect to the yoke by means of a flexure assembly which eliminates the need for a true pivot between the two elements. The elements are shaped so as to maintain a constant small air gap therebetween so as to maximize the magnetic efficiency of the device while eliminating wear. The device is operated just below saturation of the magnetic circuit in order to maximize efficiency. In addition, the actuator includes several features for maximizing its speed and operational efficiency.

Abstract: There is disclosed an improved drive circuit for a print element actuator wherein the current applied to the actuator has a fast rise mode which is terminated when a predetermined level has been reached. Current is allowed to slowly decay through the circuit until it reaches a second and lower predetermined level. The circuit is self-timing and self-compensating for variations in voltage or actuator impedance.

Abstract: An electromagnetic flowmeter using an exciting current of a rectangular wave form supplied to an exciting coil for excitation, wherein a DC voltage produced by rectifying a frequency power source, is applied by way of a voltage regulating circuit to an exciting circuit, and a switching device is connected in series between the exciting circuit and the voltage regulating circuit and is controlled by a DC reference voltage determining the level of the exciting voltage and a timing signal determining the switching timing for the exciting current. The invention enables accurate and rapid control of the waveform of the exciting current, reduces costs, and can be used for different voltages without any substantial change of circuitry.

Abstract: A controlled force variable reluctance actuator. A variable reluctance actuator having a moving element operated by a solenoid is provided in which the current in the solenoid is controlled by a signal representative of the flux density in the magnetic circuit of the actuator. The signal is produced by a Hall effect device placed in the magnetic circuit. Preferably, the Hall effect device controls the current in the solenoid by controlling its duty cycle; however, continuous control of the current may also be employed. Alternative embodiments are provided for a constant force actuator, an actuator whose force-displacement characteristic is altered, and an actuator in which the force may be selectively controlled. An embodiment is also provided for selectively controlling the position of the moving element based upon measured electric and magnetic parameters of the actuator.

Abstract: A controlled force variable reluctance actuator. A variable reluctance actuator having a moving element operated by a solenoid is provided in which the current in the solenoid is controlled by a signal representative of the flux density in the magnetic circuit of the actuator. The signal is produced by a Hall effect device placed in the magnetic circuit. Preferably, the Hall effect device controls the current in the solenoid by controlling its duty cycle; however, continuous control of the current may also be employed. Alternative embodiments are provided for a constant force actuator, an actuator whose force-displacement characteristic is altered, and an actuator in which the force may be selectively controlled. An embodiment is also provided for selectively controlling the position of the moving element based upon measured electric and magnetic parameters of the actuator.

Abstract: The present invention is directed to a system for driving a solenoid valve for an internal combustion engine in which the period of a solenoid valve holding pulse signal is preset, and even if an output time of an injector ON control signal changes in response to some particular engine operating conditions, the end of the output time of the injector ON control signal and that of a solenoid valve holding pulse signal are rendered completely coincident with each other. Therefore, the solenoid valve can be controlled accurately at a predetermined injector ON time, thus permitting an appropriate fuel injection.

Abstract: A variable reluctance actuator, of either the linear or rotary type, having a moving element operated by a solenoid, is controlled by a Hall effect sensor signal representative of flux density in the magnetic circuit of the actuator. The actuator may be operated in either a constant-force control mode, or a position-sensing or control mode. Substantially constant force, independent of position of the actuator's movable element, is obtained by varying, rather than stabilizing, the sensed magnetic field during movement. Position sensing, independent of actuator force, is obtained by variably controlling the magnitude of the excitation current of the Hall effect sensor in response to the magnitude of the coil current and Hall sensor output.

Abstract: A circuit for driving a solenoid clutch in which an input side rotating member and an output side rotating member are separated by a gap at the completely disengaged state comprises a voltage generator capable of generating at least the rated voltage of the solenoid clutch and an initial exciting voltage by which a minimum attracting force for the engagement is provided to an electromagnet of the clutch, and a controller for controlling the supply of the output voltage from the voltage generator in response to a command to engage the solenoid clutch in such a way that the rated voltage is applied to the solenoid clutch after at least the initial exciting voltage is applied to the solenoid clutch for a predetermined period. The application of the initial exciting voltage makes the electromagnet to produce a week attracting force, so that the transmitted torque of the solenoid clutch is small. In this state, the solenoid clutch is completely engaged without shock by the application of the rated voltage.

Abstract: This invention relates to DC solenoid actuator circuits.A DC solenoid winding located to act on an armature, is connected across a rectifier connected to an AC supply. A capacitor is provided across the winding so that the initial voltage applied to the solenoid winding is greater than the average actuating voltage.One terminal of the rectifier is connected to the AC supply via a switch which can either include in that circuit a capacitor or shunt that capacitor. The switch is mechanically linked to the armature of the solenoid winding so that at a predetermined point during the stroke of the armature the switch is operated to include the capacitor in the circuit so as to lower the actuating voltage for the solenoid.

Abstract: A solenoid drive system includes a driver circuit which functions to gradually increase current flowing through a solenoid coil. The attracting force created by the solenoid is proportional to the current flowing through the solenoid coil. When the attracting force becomes greater than a load including the plunger, the plunger moves toward the operating end. At a time when the plunger reaches the operating end, the current is still in the increasing curve and, therefore, an excess force is minimized. This functions to minimize noises created by the plunger movement.

Abstract: A circuit for controlling a solenoid clutch wherein a gap is present between an electromagnet and an associated attracted member when in the disengaged state. The circuit controls the level of exciting current supplied to an exciting coil of the solenoid clutch in such a way that the width of the gap is first reduced to zero and then the slip rate of the solenoid clutch is gradually changed from 1 to 0, whereby the solenoid clutch gradually reaches the completely engaged state, making it possible to smoothly engage the solenoid clutch without the occurrence of mechanical shock.

Abstract: A method of and apparatus for controlling the energization of an electromagnetic fuel injection valve in response to the production of an injector control pulse in an electronic fuel injection system. The driver circuit operates a current regulating power transistor into saturation until the current through the solenoid coil of the injector valve attains a predetermined peak current value. A comparator circuit deactivates the power transistor to stop the build-up of current through the coil. A switched free-wheeling circuit is enabled, remains activated, and starts conducting when the power transistor is deactivated by the comparator circuit so that some current continues to be supplied to the solenoid coil when the power transistor is off, thereby causing the current through the coil to decay slowly.

Abstract: Electrical apparatus is disclosed in which a line voltage supplies current to an electrically operated solenoid through an operable switch interconnected therebetween. A control circuit is coupled to the switch and controls the operation thereof such that the control circuit operates to increase the duration of current flow to the solenoid when the line voltage level decreases. The control circuit includes appropriate circuitry for generating a reference voltage independent of the line voltage level, for generating a control voltage proportional to the line voltage level, and for operating the switch to permit current flow to the solenoid whenever the control voltage exceeds the reference voltage. The control circuit can also include circuitry to increase the duration of current flow to the solenoid upon the occurrence of vibration with the solenoid above a predetermined level, and/or for increasing the duration of current flow upon initial energization of the solenoid.

Abstract: A D.C. power control for a D.C. solenoid actuator which may be used for a D.C. solenoid operated valve uses a timer circuit for switching from an initial high pull-in power after a predetermined delay to a low hold power for the valve solenoid utilizing a pulse control where the valve "on" time is held constant and the "off" time is varied. The pulses are high frequency to prevent the valve from switching with each of the pulses while enabling the average current in the valve solenoid coil to be controlled independently between the pull-in and hold current values.

Abstract: To energize an electromagnetic clutch or other electromagnetic device having a movable armature, a voltage is applied across the coil of the device to cause an initial current to flow therethrough. A current dip upon initial movement of the armature is detected, and in response, a substantially linearly increasing current is applied to the coil, establishing a controlled movement of the armature.

Abstract: A device is provided that begins an electrical starting mode in a parallel circuit configuration providing an improved speed of response and after an interval of time, current is switched to a series circuit configuration for operation during a run mode. The device is initially energized at several times the power normally required to activate a coil and switching means is thereafter utilized to reduce power to a normal requirement soon after the coil is energized.

Abstract: A magnetic sensing device for controlling power required for maintaining an armature in a closed position on a stator, characterized by a soft-iron shunt extending between and spaced from the armature and stator for conducting a magnetic field therebetween and a magnetic field sensor between the stator and the shunt for monitoring the magnetic field and for controlling power to a coil of the stator.

Abstract: A drive circuit for an electromagnetic device including a solenoid includes a transistor in series with the solenoid and a current sensing resistor. A comparator receives a voltage signal depending on the current flow in the solenoid and by way of an "AND" gate renders the transistor conductive when a control signal appears and non conductive when the current flow exceeds a set value. A first monostable circuit modifies a reference voltage applied to the comparator and reduces the set value of the current after a predetermined time so that the solenoid is initially energised at a high current value which is then reduced to a holding value. The circuit includes a second monostable circuit which causes the transistor to be switched on and off when the current has attained the high value and when the current is at its holding value.

Abstract: An analog duty cycle to BCD converter for receiving pulsed digital signals (10) from an electronic computing unit (11) for operating an electromagnetic operated exhaust gas recirculation valve (12) having a plurality of valve actuators each responding to a binary valued voltage signal. The converter receives pulsed electrical signals (10) and through a low pass active filter means (14) and a comparator means (18), generates binary weighted control signals (22) for operating power transistors in a power switch means (24), a threshold means (20) provides a plurality of threshold voltage signals to the comparator means (18) to generate the control signals (22).

Abstract: In the lifting magnet system disclosed herein, demagnetization and releasing of a load are accomplished without switching inductively loaded d.c. power by employing a.c. energization, through respective bridge rectifiers, of entirely separate lifting and drop coils.

Abstract: A solenoid driving circuit for supplying an exciting current whose level suddenly increases at the beginning of the flow of the current has a voltage inducing circuit for providing a pulse-like current component which suddenly increases at the beginning of the flow of the exciting current, a unidirectional element for supplying the pulse-like current component to the solenoid, a voltage limiting element for limiting the level of the pulse-like current component and applying a d.c. power to the solenoid, and a circuit for providing a stand-by current and the holding current to the solenoid, whereby the solenoid is effectively supplied with sufficient energy for driving it at high speed and the power required for maintaining the operation of the solenoid is reduced.

Abstract: An apparatus and method is provided for energizing a multiple-turn winding of an electromagnetic coupling having an armature and a rotor separated by an air gap; in response to the closure of the air gap, the energization of the winding is reduced so as to reduce the torque coupling between the armature and rotor. By reducing the initial torque coupling between the armature and rotor the frictional vibrations of the coupling--which occur during engagement of the armature and rotor and which generate audible noise--are reduced and the coupling engages more smoothly and quietly. Preferably, the energization of the winding is reduced in response to the increased magnetic inductance of the winding resulting from the closure of the air gap between the armature and rotor. Also, the torque coupling between the armature and rotor is preferably minimized in response to the increased magnetic inductance so as to provide 100% slippage upon initial contact of the rotor with the armature.

Abstract: The invention relates to a circuit arrangement for actuating exciting coils for electromagnetic switchgear. A transistor is connected in series with the exciting coil, as an electronic switch. Parallel with the series connection are a capacitor and a clock generator, which opens and closes the transistor with a certain frequency. Thereby, upon opening, a defined turn-off delay of the electromagnetic switchgear, and upon switching on, with the use of a timing element which at first deactivates the clock generator, the effect of a d-c saver circuit for electromagnetic switchgear can be achieved.

Abstract: An electromagnet driving circuit particularly suited for use in impact printers as a means for driving to move a printing hammer includes a current control circuit for controlling a driving current to be applied to an electromagnet. In one aspect of the invention, a feed back circuit is provided between a voltage source and the current control circuit so as to compensate for fluctuations at the voltage source. In another aspect of the invention, the current control circuit is structured to use a temperature-dependent reference voltage in determining the level of the driving current thereby allowing to carry out a temperature-compensated operation.

Abstract: A solenoid driver circuit has one transistor and a diode coupled to a solenoid and controlled by a logic circuit to apply a desired current to the solenoid. The transistor is turned on and off using a logic flip-flop to sense a voltage comparison with a peak current. A logic signal is generated as a function of the predetermined length of time, and an output signal is coupled to the base of the transistor to control its on/off states. The magnitude of the peak current is a function of an applied analog voltage. Thus, the magnitude of the average current in the solenoid coil is a function of the applied analog voltage. Also, a dither signal can be summed with the analog signal to minimize the effects of solenoid mechanical sticking and magnetic hysteresis.

Abstract: A solenoid driver circuit has reduced power consumption by switching the solenoid coil current during a decay period from an initial peak current to a lower magnitude sustaining peak current. Current decays from the sustaining peak current magnitude for a predetermined length of time to a lower current level. Two transistors and a Zener diode are operatively connected to the solenoid and controlled by a logic circuit to apply the desired current to the solenoid. A sense resistor is coupled in series with the solenoid to sense current in the solenoid. The Zener diode is coupled in parallel with the sense resistor to provide a current decay path from the solenoid parallel to the sense resistor. The two transistors are turned on and off using logic flip-flops to sense voltage comparisons with the initial peak current voltage, the sustaining peak current, and the sustaining low current.

Abstract: For controlling a pulse-operated electromagnetic valve, an energization voltage is applied to the actuating coil of the valve in response to a leading edge of the pulse to initiate an energization current. When the current reaches a predetermined peak value the voltage is decoupled from the coil to allow a circulating current to flow through a first path to decrease it at a higher rate. The circulating current is switched to a second path when it reaches a medium current value to decrease it at a lower rate. When the decreasing circulating current reaches a lower holding current value which is necessary to hold the valve operated, the voltage is coupled again to the coil to reinitiate the energization current, and when it reaches a higher holding current value lower than the medium current value the voltage is decoupled to reinitiate the circulating current.

Abstract: An electrical feed and control circuit for a drive arrangement of the pump piston of a spray gun which comprises a coil and an oscillating armature, employs an input for connection to an alternating current network, an output leading to the oscillating armature coil, a half-wave suppression circuit optionally connectible by way of a transfer switch, a phase-angle control circuit connectible and disconnectible by the transfer switch in common with the half-wave suppression circuit, the phase-angle circuit including a timing element comprising a fixed resistor and a capacitor, and a second phase-angle circuit -having a timing element containing a variable resistor.

Abstract: A system for controlling current flow to the actuating coil of a contactor or the like. A solid state switch is provided for gating current flow to the coil, and operated by an oscillator stage. A time delay causes the oscillator to operate at a high duty cycle when power is initially applied, allowing a relatively high current to flow to the contactor coil to operate the contacts. Subsequently the control causes the oscillator to operate at a low duty cycle, wherein the solid state switch passes a significantly lower current flow to the coil to maintain the contacts in position.

Abstract: A solenoid driver circuit has reduced power consumption by providing relatively fast current decay to a sustaining low current after an initial peak activation current. Subsequent sustaining current peak applications have a smaller magnitude than the initial peak current and are followed by slower decays for a predetermined length of time to a lower current level. Two transistors and a Zener diode are operatively connected to the solenoid and controlled by a logic circuit to apply the desired current to the solenoid. The two transistors are turned on and off using logic flip-flops to sense voltage comparisons with the initial peak current voltage, the sustaining peak current, and the sustaining low current. A logic signal is generated as a function of the predetermined length of time, and an output signal is coupled to the bases of the two transistors to control their on/off states.

Abstract: A DC current control is provided for inductive loads which achieves high energy efficiency even though the supply voltage may be subject to considerable variations.The inductive load may be a DC motor, a solenoid, or similar device. The electric power is applied directly to the inductive load through a switching means which closes the circuit to apply a charging current to the inductive load for fixed on periods of time.A discharge path is provided for the inductive load when the switching means opens the charging circuit. The discharge current is monitored, and when it decays to a selected value, the switching means is again closed for the fixed on charge time.

Abstract: A control unit and method for operating a gap-type electromagnetic clutch or brake is provided which reduces audible chatter, screeching caused by belt slippage and related wear and tear on the driving and driven components. The operating winding of the clutch or brake is energized to cause the gap between an armature and rotor to close, energization of the winding is then reduced to initially reduce the torque coupling between the armature and rotor and finally energization of the winding is gradually increased to full energization so as to provide a gradually increasing torque coupling between the armature and rotor.

Abstract: A voltage compensating driver circuit uses a resistor and a zener diode to remove the effect of potential difference between logic ground and power ground on the comparative function of the circuit and the supply voltage is applied as an input to the comparative function.

Abstract: A protective control system is provided for stopping an engine-driven pump when a fault condition such as low oil level, low oil pressure or high temperature occurs in the engine. The protective control system includes an electric battery, a solenoid valve regulating fuel (or air) flow to the engine and energizable from the battery, an electronic circuit energizable from the battery for controlling the solenoid valve, and fault-sensing switches for controlling the electronic circuit and shutting off the fuel supply to stop the engine upon occurrence of a fault. The electronic circuit includes a solid state voltage regulator device connected between the battery and the solenoid valve, and this device includes an adjustment terminal which is biased to control the power supply to the solenoid valve. The electronic circuit further includes a transistor which controls the bias on the adjustment terminal and the transistor, in turn, is responsive to operation of any one of the fault-responsive switches.

Abstract: A control circuit arrangement for an electromagnetically operated power tool has a primary circuit including a solenoid and a semi-conductor switch, in series, the semi-conductor switch being capable of being triggered into a conducting state upon application of a trigger signal from a trigger control circuit. The trigger control circuit is actuated upon closure of a main trigger switch which is connected in series with the solenoid and the semi-conductor switch in the primary circuit for supplying current to the solenoid. Thus, should the semi-conductor switch fail due to a short-circuit, the power supply is disconnected from the solenoid the moment the operator releases the main trigger switch so protecting the solenoid. The semi-conductor switch is preferably a thyristor. An additional circuit is preferably provided for preventing the thyristor from firing a second time if the main switch remains closed.

Abstract: A switching type control unit (20) for activating fuel injectors (50) of an internal combustion engine. The control unit (20) including a plurality of switching circuits (60) for turning on and off associated hybrid power circuits (80). The hybrid power circuits (80) communicate the increased level of voltage generated by a single boost voltage generator (70) to particular injectors (50).

Abstract: A control device is proposed for an electromagnetic engine valve or an electromagnetic final control element. The control device operates with closed-loop current control, and the maximum current is ascertained via a measuring resistor located in series with a switching transistor, while the free-running circuit is controlled in accordance with time. This control in accordance with time is effected via a comparator having dynamic positive feedback and acting as a comparison stage. The free-running control circuit includes a diode for protective purposes switched parallel to a transistor.

Abstract: A control circuit for an electromagnet includes a main current control element in series with the electromagnet winding and controlled so as to switch on and pass a "pull-in" current for an initial period and to control the current to a lower "hold" level during a subsequent period. A capacitor is connected in series with a diode and a transistor across the winding and the transistor is controlled to switch on during the change from "pull-in" to "hold" so that the capacitor is charged up during this change. A second transistor is connected in series with a second diode to permit reverse current flow from the capacitor to the winding during switch-off to hasten collapse of the flux in the winding and overcome the drop-out delaying effect of eddy currents in the electromagnet core.

Abstract: An embodiment of the present invention provides an excitation arrangement suitable for use in producing a pulse-shaped field of substantially constant intensity. To start-up the current at the beginning of a pulse, a coil (1) is fed with a high voltage (line 3) via an ignitable and blockable power semiconductor (7). For the duration of the pulse, switch-over is then effected to the supply of a lower voltage (line 4) by means of a power transistor (31) controllable to a constant current. Free-running diodes are used to decay the current. One coil end (2) is preferably connected via an FET (7) which is controllable to a constant voltage, to the high voltage; via an FET (30), which is likewise controllable to a constant voltage, to the lower-voltage (4); and via a controllable FET (52) to a reference line (6). Corresponding FET's (50, 51, 31) are provided at the other coil end (5).

Abstract: A driver for the excitation coil in the electromagnet of an electromagnetic flowmeter, wherein the fluid to be metered is conducted through a flow tube to intersect the transverse magnetic flux field created by the electromagnet. The driver includes an a-c line rectifier whose output is coupled to the coil by a pair of switching transistors, the control electrodes of which are connected to the output of a comparator having first and second input terminals. Applied to the first terminal of the comparator is an alternating square wave voltage, each cycle of which has a positive and a negative gating pulse such that the transistors are alternately actuated, the arrangement being such that the rectified output is applied by the transistors to the coil with a polarity which is alternately reversed.

Abstract: A solenoid driver circuit for a solenoid-operated fluid dispenser in which a valve is operable to dispense a fluid under the control of the solenoid. The driver circuit receives externally applied turn-on and turn-off signals and energizes the solenoid in response to these signals. The driver circuit is responsive to a turn-on signal to couple a pull-in voltage across the solenoid to pull in a solenoid valve armature. The driver circuit is also operable to sense the level of current in the solenoid. When the solenoid current reaches a preset peak current level, the pull-in voltage is removed from the solenoid and replaced by a hold-in voltage. When the hold-in voltage is applied to the solenoid, the driver circuit is operable to control the level of the hold-in voltage in order to maintain a preselected hold-in current in the solenoid. The driver circuit controls the solenoid current so that it makes a gradual transition from the peak solenoid current level to a steady state hold-in current level.

Abstract: An integrated power circuit for driving an inductor load including an integrated current sensor is provided. The integrated circuit includes a power transistor in series with the inductive load for operationally conducting a load current of at least 1 amperes and circuitry for applying a predetermined operational voltage across the power transistor. A sensing transistor having an emitter-base junction area less than 10.sup.-3 times the emitter-base junction area of the power transistor and a base terminal common with the base terminal of the power transistor is included in the integrated circuit as is circuitry for applying a predetermined voltage across the sensing transistor. The integrated circuit further includes circuitry for applying a voltage to the common base terminals to activate both the power and sensing transistors whereby a small current mirroring the load current flows through the sensing transistor. The circuitry also senses the current level of the activated sensing transistor.

Abstract: A device for controlling an electromechanical transducer such as a proportional electromagnetic valve, in which a pulse signal having a constant period shorter sufficiently than the minimum response time required for the displacement of the plunger of the proportional electromagnetic valve over its predetermined full stroke is applied to the electromagnetic coil of the proportional electromagnetic valve to superpose a very small vibratory stroke component on the stroke of the plunger, and the duty cycle of the pulse signal applied to the electromagnetic coil is varied so as to urge the plunger in directly proportional relation to the variation of the duty cycle without substantially giving rise to mechanical hysteresis in the stroke of the plunger.