Abstract: A driver circuit for controllably connecting an inductive load to a source of electrical power in response to an input control signal is provided. The inductive load includes an inductive winding of a solenoid. The driver circuit controllably connects and disconnects the inductive load to and from the source in response to a first control signal and controllably provides a discharge path for a flyback current of the inductive load in response to a second control signal. The driver circuit senses both the energizing current and the flyback current and responsively provides an energization path and a flyback discharge path in a non-overlapping manner.

Abstract: An electrical contactor has first and second contacts movably mounted to engage for achieving continuity in an electrical circuit, via an electromagnet and armature defining a magnetic circuit with an air gap that closes in a first position of the contactor and opens in a second position of the contactor. A controller switches an alternating current voltage to the coil of the electromagnet during a timed portion of each AC half cycle, and senses the current level in the coil in a feedback loop. The controller adjusts the voltage-on time to achieve a predetermined average current as needed for accelerating the armature or coasting during a closing operation, for holding the armature in place when closed, etc. In order to sense whether the contactor is presently open or closed, the controller monitors and stores the phase angle between the previous voltage zero crossing and the time of voltage turn-on.

Abstract: After an injector current for opening a fuel injector is fed thereto, energization on the fuel injector is stopped to reduce the injector current towards a holding current level for keeping the fuel injector at an open state, a flywheel circuit being inoperative. Before a closed loop for controlling the injector current at the holding current level is formed, the flywheel circuit is made operative, whereby an influence of the operational delay of a circuit forming the closed loop can be reduced and further the injector current can be swiftly transferred to the holding current level before it falls largely.

Abstract: Auxiliary power steering for motor vehicles with an electromagnetically activated proportional valve whose magnetic coil is regulated as a function of a pulsed voltage frequently produces whistling sounds. The invention remedies this in that the starting sides of the voltage pulses commence at different time intervals with respect to each other. The resultant negligible "white noise" is not disturbing in the general noise level of a motor vehicle.

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 contactor has an armature, a pull-in coil and a holding coil. When the system is energized through a first switch such as a thermostat, the low current holding coil is energized in preparation for holding the armature pulled in after the pull-in coil is energized and the armature has finished its power stroke. A solid-state switching device and the pull-in coil are connected in series between both terminals of a power source. A control circuit causes the solid-state switching device to be conductive the instant power is supplied to the circuit through the first switch. One embodiment of the control circuit is based on logic gates. RC circuits associated with the gates keep the solid-state switching device and pull-in coil conducting long enough for the armature to pull-in. After the solid-state switching device turns on, the transistor is controlled to turn off, deenergizing the pull-in coil while the holding coil holds the armature in until the first switch opens and power input is discontinued.

Abstract: A low loss recirculation apparatus for recirculating current through an inductive load (101) includes an active recirculation circuit. The low loss recirculation apparatus includes a control device (201) with a drive output (203) that provides a drive signal (205), and a recirculate output (207) that provides a recirculation signal (209). A device (103) provides drive current, along a path (109), to the inductive load (101) responsive to the drive signal (205). A gated recirculation circuit (202), recirculates current, along a path (115), through the inductive load (101) responsive to the recirculation signal (209).

Abstract: Solenoid control circuitry can be used with either a first solenoid requiring a relatively large holding current or a second solenoid requiring a relatively small holding current. A solenoid connected with the solenoid control circuitry is initially energized to effect operation of the solenoid from an unactuated condition to an actuated condition. A detector detects whether a characteristic of the initial energization of the solenoid corresponds to a characteristic of the first solenoid or the second solenoid. The solenoid control circuitry varies the amount of holding current supplied to the solenoid as a function of whether the detector detects the first solenoid requiring the relatively large holding current or the second solenoid requiring a relatively small holding current. A fault detection circuit is provided to interrupt energization of the solenoid in the event of an excessive flow of current.

Abstract: The coil of an electric control device is energized by ac power controlled by a remotely generated logic level signal through a control module mounted in a cavity in the exterior of the device housing. The module contains a pair of back-to-back silicon controlled rectifiers (SCRs) mounted on a finned aluminum wall of the module which serves as a heat sink. An opto-coupler comprising a light emitting diode (LED) energized by the logic level signal and an opto-triac in series with resistors connected across the gates and cathodes of the back-to-back SCRs provides electrically isolated control of the conduction angles of the SCRs by the logic level signal.

Abstract: An energizing circuit for a permanent magnet internal combustion starter motor having a pull-in coil, a hold-in coil and plunger contacts connected to a single terminal which is switchable between a direct current power source and ground which are magnetically independent.

Abstract: In a engine and associated fuel injector failure detection circuit, the engine having at least one combustion chamber, a battery, and at least one fuel injector having a high side and a low side terminal for introducing a fuel in the at least one combustion chamber, the fuel injector failure detection circuit comprising a one shot timer for transmitting a constant voltage state signal output when the fuel injector reaches a set current threshold at a start of an injector current peak time duration. A voltage sense comparator is provided for transmitting a low voltage state signal output when the low side terminal of the fuel injector produces a fly-back voltage pulse. A mechanism for monitoring current of the fuel injector during a rise time duration and the peak time duration ia also included.

Abstract: A DC electromagnet apparatus that can prevent an excessive making coil current caused by changes in a power supply voltage. The electromagnet has an operation coil, a switching device, and a current detecting resistor connected in series. A one-shot pulse generating circuit produces a one-shot pulse having a pulse width corresponding to the duration of the making coil current flowing through the operation coil to close the electromagnet. A Miller circuit generates, based on the one-shot pulse, a trapezoidal pulse having a predetermined rising rate, a predetermined peak value, and a pulse width substantially equal to that of the one-shot pulse. A comparator produces an ON control signal that controls the switching device in such a manner that the making coil current becomes proportional to the trapezoidal pulse.

Abstract: Apparatus for closing a circuit breaker of a circuit that carries a substantial current includes a terminals (W1, W2, W12, W13, W14) for connection to an available source of electric power. The electric power available is typically 24 VDC, 48 VDC, 125 VDC or 120 VAC. An actuator including an electric motor M and a solenoid S both designed to operate on 24 VDC first cocks charging springs and then releases the charging springs to close the circuit breaker. A controller including a microprocessor U3 is connected to and derives power from the connected terminals and produces a pulse width modulated control signal (RUN; CLOSE) for controlling the actuator. The duty cycle of the pulse width modulated signal is adjusted in relation to the electric power supplied by the selected source so that the power supplied to the motor and relay functions effectively as the required 24 VDC power. Sensors J1 sense the condition of the charging springs, a charging cam, the circuit breaker, etc.

Abstract: A solenoid valve control system controlling a solenoid valve which changes a solenoid valve state between an opened state and a closed state by applying pulsed electric power thereto. The solenoid valve control system includes an ammeter for detecting a current value applied to the solenoid and a control device for controlling electric power supplied to the solenoid. The control device has a duty control section which controls an ON-OFF ratio of pulsed electric power repeatingly applied to the solenoid and a correcting section which corrects an output from the duty control section according to the current value detected by the ammeter. Therefore, the line pressure is kept at a precise target value.

Abstract: A generic solenoid driver circuit and circuit board may be used in a plurality of application specific driver circuits. The circuit board includes a plurality of binary driver circuit locations, proportional circuit locations, and jumper locations. Electrical components are inserted at those locations needed for the circuit to perform the functions of the specific application. Microprocessor controlled switches may be substituted for the jumper locations so that the solenoid driver circuit configuration may be software controlled.

Abstract: An electronic fuel injector driver circuit is a high speed operator of electromagnetic fuel injector valves for internal combustion engine. The drive circuit includes a solenoid coil for each electromagnetic fuel injector. A one shot timer circuit sends a predetermined timing signal to a first controller circuit interconnecting the one shot timer circuit and the solenoid coil wherein the predetermined timing signal is used to control the high side of the solenoid coil. A second controller circuit is connected to the solenoid coil and controls the low side of the solenoid coil in response to the predetermined timing signal. A switchable voltage reference circuit is connected to the second controller circuit and controls current through the solenoid coil.

Abstract: An electronic switching arrangement for controlling a coil includes a capacitor for energizing the coil by momentarily passing a current therethrough so as to generate a required attractive force for movement of the armature. After movement of the armature, only a lower holding current is supplied. Arranged parallel to the coil is a voltage divider which cooperates with a transistor to detect and evaluate an unintentional movement of the armature.

Abstract: A solenoid drive circuit comprises a timing circuit which activates a voltage control circuit causing a voltage regulator to reduce the voltage output by the driver circuit from a high initial level to a lower holding level sufficient for the solenoid to remain energized. The timing circuit comprises a resistor and capacitor in parallel and the duration of the initial higher voltage output is inversely proportional to the input voltage level. The timing circuit activates a transister in the control circuit changing the equivalent resistance between the adjustment terminal of the voltage regulator and ground thereby causing a reduction in the output voltage.

Abstract: In a vehicle electromagnetic clutch control device, clutch current calculating means outputs a clutch current analog signal according to given travel control data and engine control data, a current difference detector obtains the difference between the clutch current analog signal and a clutch current feedback signal, a first output transistor is operated according to the difference thus obtained to energize the electromagnetic clutch, the clutch current flowing in a second output transistor is detected with a current detecting resistor, and a voltage corresponding to the clutch current thus detected is applied to an operational amplifier, so as to output the clutch current feedback signal with the aid of a reference resistor, a feedback resistor and the amplification factor thereof. An adjusting resistor is connected in parallel to the reference resistor, to adjust the clutch current.

Abstract: A circuit (16) having an extended breakdown capability is provided for switching an inductive load driver (12). The circuit (16) includes a first switch (18) for providing a first drive voltage when the first switch (18) is closed. A second switch (20) is provided for receiving the first drive voltage from the first switch (18) and delivering the first drive voltage to the inductive load driver (12) when the second switch (20) is closed. The second switch (20) limits the voltage across the first switch (18) to a predetermined level when the first switch (18) is open. A third switch (22) provides a second drive voltage to the inductive load driver (12) when the third switch (22) is closed.

Abstract: A relay output circuit is provided which enables a relay coil to be connected to a possibly variable input DC voltage without requiring relatively high power components to be used. The relay coil is provided with sufficient current to actuate it and then the actuating current is decreased to a lesser magnitude which is sufficient to maintain the relay in an actuated position. In order to accomplish this, the relay output circuit first provides current to the coil through a single resistor and then effectively connects an additional resistor in series with the initial resistor to decrease the current flowing through the coil. The second resistor is effectively added to the circuit by turning off a field effect transistor that provides a shorting across the second resistor when it is in a conductive state. The conductive state of the field effect transistor is controlled by a capacitor which charges for a preselected period of time following a change of state of an input circuit point.

Abstract: An electrical contactor including a control system for regulating the voltage applied to the contactor's coil. The control system is adapted for gradually increasing the applied voltage and the resultant current through the coil so that contact closure takes place under controlled conditions. The control system enables the contacts in the contactor to be closed with a minimum of contact bounce upon activation of the contactor.

Abstract: A system and method for operating high speed solenoid actuated devices such as electromagnetically operated high pressure fuel injectors require an initial high power boost to start the movement of an armature followed by a medium power boost to continue the movement of the armature to its end position and a low power control to hold the armature at its end position so that when the power is removed, the armature returns to its rest or beginning position. The system here details the logic and control necessary to provide six stages of power control, including both voltage and current control, to accomplish high speed operation both in moving the armature from its beginning to end position but also to return the armature from its end to its beginning position.

Abstract: A control system for an electromagnetic device prevents overheating of the coils to permit optimizing design parameters without the need for excessive safety factors. A pull coil circuit feeds a high current to pull windings for a preset time interval after receipt of an initiating voltage. A hold coil circuit feeds a holding current to holding windings with a reduced flux after receipt of an initiating voltage only if it exceeds a preset voltage threshold. The hold current is cut off when the initiating voltage falls below a preset threshold. The pull coil circuit is rendered inoperative for a preset time interval after current is discontinued to ensure adequate cooling between operations.

Abstract: In a vehicle electromagnetic clutch control device, a PWM modulator is provided in a microcomputer. In the microcomputer, a PWM modulation signal is calculated according to travel control data and engine control data and is then outputted. The PWM modulation signal is buffered by a digital signal buffer, the output of which is passed through a PWM smoothing filter to remove high frequency components of the signal. The output of the PWM smoothing filter is input to an analog buffer amplifier to output a substantially DC current instruction signal to a PWM comparator.

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 solenoid driver applies an actuation current to a solenoid for a predetermined period and a lower holding current thereafter. A switching device pulses the applied current within upper and lower limits to maintain the actuation and holding current amplitudes, the pulses being integrated by solenoid inductance into a substantially steady-state current. A multiprocessing unit determines the amplitudes of solenoid current. A signal representative of desired current amplitudes is compared with a signal representative of measured solenoid current, and a signal representative of the difference therebetween is used to control the switching device. Voltage developed across a resistor in series with the solenoid is input to a differential amplifier having connected to its output a peak detector that mimics the decay rate of current in the solenoid, the signal representative of measured solenoid current being obtained from the peak detector.

Abstract: A circuit comprising a switch series connected to a load; a first and second current recirculating branch alternately connectable parallel to the load, for reducing the current in the same; and a logic control unit for opening and closing the switch and recirculating branches, so that the load is supplied with a current rising to a peak value and then falling rapidly to and oscillating about a lower hold value; a transistor being provided for reducing the voltage supplied to the load by the first recirculating branch at the end of the fast fall phase, so as to eliminate uncontrollable operating zones and prevent the load current from falling below the hold value.

Abstract: A circuit arrangement for driving a group of relays includes a voltage regulator for supplying a normal holding voltage and for supplying a briefly increased pick-up voltage upon connection of each additional relay. An ammeter recognizes the increase in current as the result of the connection of each additional relay and generates a control signal to the voltage regulator for increasing the voltage. Simple and effective control of the relays without high heat loss is thus achieved without requiring individual sensor lines and the like.

Abstract: The coil holding current of a contactor is regulated to the lesser of two measurements of coil current during each cycle of the full-wave rectified control voltage to compensate for induced flux in the coil generated by load current through the main contacts of the contactor, thereby preventing uncontrolled drop out of the contactor.

Abstract: A synchronizing current regulator whose clock frequency is able to be readjusted is provided in the case of a circuit configuration for the synchronized supply of an electromagnetic user with regulation which is acted upon by a control signal representing the difference between the instantaneous signal at the user and a predeterminable reference signal.

Abstract: A fuel pump control circuit includes an SCR for controlling, after turning on of an ignition switch, power supply from a power source to a fuel pump circuit for driving a fuel pump (this SCR being turned on by a gate current supplied from the power source through a first conduction path), a timer circuit for shunting the gate current, which flows into the first conduction path, to a second conduction path when a predetermined time elapses after turning on of the ignition switch, and a current limiting resistor inserted in the first conduction path.

Abstract: A control system for applying power to a solenoid operated valve in a well completion within a borehole. The control system includes a programmable power supply for selectively applying electric power to a solenoid coil of the valve. The control system operates to apply a higher value of current to the solenoid to open the valve and a second lower value of current to maintain the operation of the solenoid in an open state and also to interrupt all current to the solenoid to close the valve. A timer controls the length of time the higher current value can be applied to the solenoid if the valve does not open and the length of delay time which must be included before again attempting to open the valve. The control system continuously monitors the state of actuation of the valve by means of an inductance monitor for determining the position of the armature of the solenoid and, thus, the state of the valve.

Abstract: An energy saving electromagnet with momentary demagnetization of this invention comprises an armature, an iron core, an exciting coil, and a controllable power source. It is provided with an energy storage means capable of generating a momentary rotation force to cause the armature to rotate slightly for momentary demagnetization after the power source is cut off. The controllable power source includes an initiation power source, a holding power source and a control circuit for turning the supply from the initiation source to the holding source, thereby enabling effective utilization of the electric power and reduction of magnetic resistance. In the holding state, there is no significant demagnetizing air gap between the armature and the iron core.

Abstract: A process for controlling and measuring the movement of an armature of an electromagnetic switching member with an excitation coil is proposed, which has the following steps: a current (i) or a voltage (u1) is applied to the excitation winding (3) in order to move the armature into a first actuatable position; before the start of the movement of the armature, the current or the voltage is raised above a value at which the armature remains in the actuated position, and before termination of the movement of the armature the current or the voltage is reduced to a defined value, which suffices to hold the armature in the actuated position; finally, the temporal variations in the current or the voltage are measured after setting of the defined value, for the purpose of recognizing the termination of the armature movement.

Abstract: A solenoid valve includes a monitoring circuit adapted to sense the current drop that occurs through the solenoid coil when the solenoid armature moves correctly, sensing of the drop being used to cause a neon to glow continuously so as to indicate correct operation of the solenoid. If the drop is not sensed, the neon is caused to blink so as to indicate incorrect operation of the solenoid. The circuit may in addition or alternatively be arranged to generate a voltage signal, upon correct operation of the solenoid, for transmission to a remotely located programmable logic controller used to control operation of the valve and like valves that form part of a pneumatically controlled machine.

Abstract: A temperature compensated control circuit includes a load transistor which passes the load current and has an on-resistance which varies with temperature. To provide temperature compensation, first and second pilot transistors are integrated with the load transistor such that as the load transistor heats-up due to the load current passing through the on-resistance of the load transistor, the first and second pilot transistors heat-up due to heat conduction from the load transistor. Each of the pilot transistors has an on-resistance which varies proportionally or similarly to the on-resistance of the load transistor. A first current source supplies a first level of current to the on-resistance of the first pilot transistor to develop a first reference voltage, and a second current source supplies a second level of current to the on-resistance of the second pilot transistor to develop a second reference voltage.

Abstract: A trigger circuit for an electromagnetic device, in particular a solenoid valve of an injection system for an internal-combustion engine, has a control element for causing excitation of the electromagnetic device to be lowered at least once and then raised after the electromagnetic device is activated. The control element has a delay circuit which slows down the rate at which excitation of the electromagnetic device changes during the lowering and/or raising action.

Abstract: Load driver circuit (10) has first and second comparators (Cphd 1, C.sub.2) which receive a load current signal (V.sub.s) indicative of current flowing through a load (11). The comparators provide, as output signals, set on and set off signals (at 21, 23) in response to comparing the load current signal (V.sub.s) with first and second thresholds (T.sub.1, T.sub.2). Driver circuitry (27, 43, 12) receives the set on and set off signals and provides a current control signal (at 18) for controlling load current. Preferably, disabling circuitry (30-34) disables the comparators (C.sub.1, C.sub.2) after and in response to the comparators providing their respective output signals (at 21, 23). Also, preferably enabling circuitry (40-42) enables the comparators (C.sub.1, C.sub.2) in response to comparing a sensed voltage (at 17), indicative of voltage at an output terminal of a switching device (12) that controls load current, with respect to a predetermined voltage (2.5 volts).

Abstract: The invention concerns a device for a.c. cut-in limitation of a power-sup unit with inductive reactance. The device has a series-connected first a.c. switch and a phase-angle control circuit by means of which a time lag can be introduced in the connection between the primary winding and the mains a.c. voltage at the point in time that cut-in takes place. The control electrode of the first a.c. switch of the floating phase-angle control circuit is connected to the output of a control circuit by means of which a trigger voltage, which is synchronized with the mains a.c. voltage, is generated, when the power-supply unit is switched in, at a selectable phase angle between 90 and 0 degrees before a zero passage of the main a.c. voltage. The trigger voltage can be suppressed before the zero passage of the mains a.c. voltage is reached in order to switch off the power-supply unit.

Abstract: A coil is connected to a voltage source by a switch enabled by a drive signal of fixed duration. Drive current in a coil is terminated by a chopper circuit if it reaches a predetermined peak level before the end of preselected rise time interval. The chopper circuit is inhibited from operation until the end of the rise time interval during which time the drive current is allowed to decay. The chopper circuit is enabled at the end of the rise time interval for chopping the drive current at an average peak current value for the duration of the preselected time. The total amount of energy supplied to the actuator is adjusted by allowing the current to decay if the peak current is reached before the end of the predetermined rise time interval and then by chopping the current at a predetermined switching rate for the duration of the preselected time of the drive signal. Short circuit protection is also provided during the predetermined rise time interval.

Abstract: A power controller for electric locks which draw large startup current surges which controls and manages the energy of a pair of storage batteries to reliably operate such electric locks and provide steady-state power to auxiliary system components both with AC power present and in the absence thereof, so long as the stored charge in the batteries is able, to thereafter maintain a steady source of power to the system as long as possible, and to be self-starting upon the return of AC power, all without ever placing the electric locks in a partially unlocked or "hung" state. The two storage batteries are normally maintained charged through an AC power source, and both cooperate to provide the surge power. On loss of AC power, both still provide surge power so long as one can maintain the steady state power, and thereafter the other battery alone provides surge power so long as possible.

Abstract: A method and apparatus for a two-pulse solenoid embossing system implementing an amplitude feedback circuit, i.e., current monitor (48), to provide precise amplitude and timing control over two current pulses (4, 5), and thereby provide precision control over the position and velocity of the embossing system's print elements (64a, 64b). To maintain the current amplitude during the second current pulse (5), the method and apparatus alternatively switches the power on and off to the solenoid coils (55) with a frequency such that a substantially constant current amplitude is maintained in the solenoid coils (55). The embossing system provides an improved solenoid body assembly (61) including a first stack of steel laminations (93), a center block (82) and a second stack of steel laminations (81). A plunger (62) is slidably connected to the solenoid body assembly (61) by shaft (63). Cavities (79) receive dowel pins (71) which are attached to plunger (62).

Abstract: A driver device for a duty solenoid valve comprises a pair of transistors 27 and 31 for controlling the excitation current level flowing through the solenoid 17 of the valve, and a transistor 45 for turning on and off the excitation current. The excitation current level is detected via an integrator 63 and A/D converter 61 by a microcomputer 62. In response to the detected excitation current level, the microcomputer 62 generates a first pulse signal (PWM signal) via OUT3 to control the level of the excitation current to a target level. Further, the microcomputer 62 outputs a second pulse signal via the OUT4 to the transistor 45 to control the duty ratio of the solenoid 17.

Abstract: A shutter, positioned between an electronic imaging device (such as a laser printer) and a film processor, is actuated by a solenoid which is driven by a driver network which isolates the solenoid coil when it is deactuated. If, after deactuation, a jam occurs, such that the shutter does not close completely, the jam is detected by a solenoid engagement sensing circuit. The sensing circuit includes a function generator, an operational amplifier having the solenoid coil connected between its input and output, an envelope detector and a comparator. The comparator produces a jam signal in response to an increase in the voltage detected by the presence of the solenoid plunger within the solenoid coil.

Abstract: The interface circuit described comprises a plurality of control stages, each of which can detect and indicate a short-circuit in the corresponding load or the associated power transistor.In particular, the interface circuit is arranged to disable a transistor permanently when short-circuits occur repeatedly in the load in order to prevent damage to the transistor.

Abstract: An excitation current control device for an automotive electromagnetic clutch includes a first and a second transistor 8 and 13 and a current detector resistor 14, coupled in series with the electromagnetic clutch. The first transistor is PWM controlled to control the amount of excitation current through the electromagnetic clutch. The second transistor turns off the excitation current in response to the disconnection signal for the electromagnetic clutch. The current detector amplifier 6 includes, in addition to an operational amplifier 61 and an input and a feedback resistor 63 and 62, an offset resistor 64 for offsetting the base current of the second transistor and the current flowing through a reverse excitation resistor 12 and the detector resistor 14. Alternatively, the offset correction for base current is effected by a software calculation.

Abstract: The present invention comprises a fuel pump controller having a silicon controlled rectifier (SCR) for supplying a power source voltage to a fuel pump circuit for driving a fuel pump when the SCR is turned on. A timer circuit is also provided for instantly turning on the SCR for a predetermined time period when an ignition switch is initially turned on so as to provide a discharge of fuel into the carburetor before the engine is activated or rotated. In addition, a controller is provided for repeatedly turning on the SCR each time the engine is rotated such that the fuel pump will be driven by rotation of the engine until such engine rotation ceases. By operation of this assembly, fuel is supplied to the carburetor for a predetermined time period before the engine begins to rotate so as to obtain an efficient and quick engine ignition despite the possible initial lack of fuel in the carburetor.

Abstract: Control circuitry is disclosed for electrical starters, contactors and the like having a starting winding and a serially coupled holding winding wherein the holding winding is shorted until the separable main contacts have closed which includes circuitry which obviates the need for relatively precise sensing of the position of the separable main contacts to control the holding winding. In one embodiment of the invention, the unshorting of the holding winding is delayed a predetermined number of cycles after the separable main contacts have closed to avoid the necessity of relatively accurate mechanical sensing of the position of the separable main contacts. In this embodiment a relatively less expensive field effect transistor or the like is used to short out the holding winding until the separable main contacts have closed. This allows the use of a relatively less expensive limit switch with a substantially smaller DC capability.

Abstract: An electric clutch actuator includes a coil having first and second windings, a first end of the first winding being connected to a source of electrical power and a second end of the second winding being connected through a switch such as an FET (field effect transistor) to ground potential. The opposite ends of the windings are connected together through another FET switch to the ground potential. An actuation circuit is responsive to a control signal to turn on the FET switches and cause electrical current to flow primarily through the first winding. The actuation circuit includes a timing circuit which turns off the FET connected to the opposite ends of the windings after a predetermined period of time to cause electrical current from the power source to pass through both of the windings.