Abstract: An electromagnetic driving circuit for driving a pendulum comprises a coil for detecting and driving a permanent magnet, a comparison circuit for comparing an induction voltage induced in the coil with a reference voltage, a generating circuit for generating driving pulses of a predetermined pulse width in response to outputs of the comparison circuit, and a driving circuit for flowing a driving current through the coil in accordance with the driving pulses. The timing at which the driving pulses are generated and/or the pulse width of the driving pulses are automatically adjusted to optimum values to improve the driving efficiency of the pendulum.

Abstract: Method and apparatus for improving the operation of an internal combustion engine of the type having electromagnetically actuated gas exchange valves, in which the detachment time lag, the delay in release of the anchor plate from the electromagnet, is compensated-for in determining the proper time to shut-off current to the electromagnet. Embodiments include measuring individual electromagnet/anchor plate couple detachment times in the factory and presetting advances in the controller microprocessor, or contact sensing the total time of detachment plus flight during operation and compensating for the detachment time depending on calculated optimum time of shut-off, or engine operating conditions, including exhaust composition, cylinder pressure, ageing, temperature, knocking, engine output, and the like.

Abstract: A device comprising an inductor connected to current supply means; a condenser designed for parallel connection to an inductive load; and switch means having a short response time and controlled so as to interconnect the aforementioned supply means, inductor and condenser according to a number of sequentially prearranged circuit configurations.

Abstract: Inductor coil (13) of a relay (12) used to supply battery power to a power load (11) of a vehicle engine control system (10) is also used to provide a substantially higher than battery voltage (V.sub.Batt) boost voltage (V.sub.Boost) for vehicle control apparatus (20). Microprocessor (21) generates a control signal (V.sub.in) having a 10:1 duty cycle for control of current excitation of the coil (13) during an effective on logic state for the relay (12). During coil current interruptions during the on logic state, energy stored in the inductor (13) is utilized via a rectifier means (26 and 27) to provide the boost voltage. During the on relay state, a movable member (14) of the relay is maintained in its actuated position since current interruptions during the on state are shorter than the relaxation time required for the movable member to assume a nonactuated state.

Abstract: A high efficiency non-dissipative snubber circuit suitable for most power supplies used in international markets is disclosed. Circuit uses diode-capacitor-inductor structure to capture input voltage equivalent and reverse polarity on snubber capacitor. No external voltage source is required.

Abstract: An electromagnetic launcher having spaced-apart rails for launching a projectile includes a plurality of stages connected to the rails for supplying makeup current during a projectile launch. Each stage includes an inductive power supply and an electrically conducting loop physically adjacent the rails for a predetermined length and including a conducting switch, such as a controlled rectifier array. As a projectile launching armature enters the loop area, a countercurrent is built up in the loop and at current zero the switch reverts to a non-conducting condition, thereby causing injection of the inductive current into the rails.

Abstract: A protective arrangement for an electromagnetic load is disclosed. In this protective arrangement, the load and a control transistor form a series circuit from the battery voltage to ground and a series circuit of a free-wheeling transistor and a free-wheeling diode is connected in parallel with the load. By coupling the base of the free-wheeling transistor to ground, this transistor is made continuously conductive provided that the polarity of the supply voltage is correct, whereas, this free-wheeling transistor blocks if the supply voltage polarity is incorrect. This assures that none of the components is in danger of being destroyed in the event that the polarity of the supply voltage is incorrect.

Abstract: A solenoid drive circuit in which a solenoid is intermittently driven while in a powered state. A diode and a resistor are connected from ground to opposite ends of the solenoid to quickly discharge the solenoid. However, during intermittent driving the resistor is short circuited.

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: The present disclosure describes circuit variants for reducing electromagnetic interference from saturable core keyboards to acceptable levels. The invention finds particular application in conjunction with capacitive-discharge scan techniques used in such keyboards. In order to attenuate the external field resulting from such techniques, a circuit is taught which effectively disconnects the scan line array from the capacitor charging circuit during the time between scans. A second variant, when added to the first, further reduces interference by disconnecting the entire scan circuit from the supply potential during the scan time thereby eliminating steady-state currents and turnoff oscillatory transients.

Abstract: A power supply/sink for use with switched inductive loads includes a transformer with a first secondary winding for generating power supply current connected in a circuit with a power supply terminal. A second secondary winding is connected in a circuit to a power sink terminal. The two secondary windings are interconnected with a controlled conduction path which is arranged to supply sink current in response to variations in the voltage at the power sink terminal.

Abstract: An electromagnet coil 2 wound on a fixed iron core 6 is energized by d.c. current supplied from a full-wave rectifier 1 to attract a movable armature 7. A transistor 10 is connected in series with the coil, a bias resistor 8 is connected across the coil to the base of the transistor, and a capacitor is connected between the base and collector of the transistor. The capacitor absorbs inductive energy stored in the coil 2 when the a.c. supply circuit is opened to thereby reduce the armature release time.

Abstract: An electromagnetic contactor for controlling the opening and closing of an electric circuit for an electric motor or the like, including a mounting pedestal including a rectifier circuit therein, a stationary iron core disposed thereon and having an operating coil wound around the same, and a movable iron core disposed oppositely to this stationary iron core to be spaced therefrom by a predetermined spacing thereby to change an AC voltage applied to the operating coil to a direct current. The stationary iron core is composed of a bar-shaped magnetic member while the movable iron core is substantially U-shaped.

Abstract: In the particular embodiment of the invention described in the specification, a circuit for interrupting the operation of a switching transistor includes a reactor connected in series with the transistor emitter and a plurality of diodes connected in series between the reactor and the base of the transistor so that the electromotive force induced in the reactor when the reactor current decreases is supplied to the base of the transistor. This makes it possible to maintain the reactor storage time when the transistor is switched off and to adjust the fall time so that the changing rate (di/dt) of the current flowing in a snubber circuit for controlling overvoltage may be minimized so that the structural restrictions imposed on the snubber circuit can be eased and reliability is improved. Noise is also reduced because the current drop rate (-di/dt) when the transistor is switched off can be minimized.

Abstract: A line printer having a suitable number of hammers which are controlled by electromagnets and which are juxtaposed with equal pitch on a carriage to effect printing while simultaneously shifting the hammers, wherein adjacent hammers are not simultaneously driven to thereby prevent malfunctions due to the influence of adjacent electromagnets.

Abstract: A passive mass-spring type of sensing device or other such device for monitoring a particular parameter, for example mechanical vibration, is disclosed herein. This device utilizes an electrically conductive coil having a given impedance disposed within a magnetic field in a way which results in relative movement between the coil and the field corresponding to the particular parameter being monitored, whereby to produce a monitoring signal in the form of a voltage which also corresponds to the parameter being monitored. The device includes a circuit arrangement for electronically damping the relative movement recited above in a substantial way while, at the same time, maintaining the monitoring signal at a measurable value.

Abstract: A control circuit for a solenoid driver for a dispenser having inherent pull-in and drop-out delays. The circuit includes a tachometer that generates pulses representative of the speed of a conveyor that conveys a substrate upon which the dispenser dispenses fluid. A sensor generates a trigger signal indicating that the substrate is at a preselected location. Delay counter circuitry, enabled through the trigger signal, generates an enabling signal after receiving a preselected number of pulses. Duration counter circuitry, enabled by the enabling signal, generates an initial driving signal of a preselected signal duration. Compensator circuitry receives the initial driving signal and modifies it so as to compensate for the pull-in and drop-out delays so that fluid is deposited for the dispensing duration upon the substrate commencing at the preselected position.

Abstract: Apparatus disclosed for regulating a substantially constant magnetic flux level in an electromagnetic contactor. In one form a flux sensing device mounted in the contactor magnetic circuit provides a linear signal indicative of the level of magnetic flux in the contactor. A linear amplifier utilizes the flux signal to regulate contactor excitation to maintain flux at a desired value. In another form digital flux sensing device switches between first and second states as the level of magnetic flux varies between first and second values. A contactor excitation circuit "chops" the contactor excitation in response to the sensing device to thereby maintain magnetic flux at a value varying between the first and second values.

Abstract: A circuit for driving a solenoid at a high speed with a choke coil, which has a pair of switching circuits alternatively turned ON and OFF by a transistor, a solenoid coil connected to one of the switching circuits, a resistor connected to the other of the switching circuits, and a choke coil connected in series with the switching circuit and in parallel with a power source. Thus, this circuit can abruptly raise an electric current flowing through the solenoid coil by utilizing the constant current characteristics of the choke coil and the current switching characteristics of the transistor.

Abstract: Apparatus for reducing noise due to switching transients in a control system having a plurality of inverting amplifiers located at a common site to receive individual switching input signals, a like plurality of relays located remotely from the amplifiers for individual energization and deenergization thereby in accordance with the switching signals, and conductors connecting the relays severally to the amplifiers, the apparatus comprising series circuits associated severally with the amplifiers, each series circuit including a resistor and a capacitor, having first terminals interconnected at a junction point and second, independent terminals, the inputs of the amplifiers being connected severally to the junction points, the input signals being connected severally to the independent terminals of the resistors, and the outputs of the amplifiers being connected severally to the independent terminals of the capacitors.

Abstract: A saturable reactor snubber to improve the recovery characteristics of a clamp diode used in a power switching circuit is provided with a secondary winding to permit saturating the reactor via a secondary current pulse in order to improve the turn-on speed of the clamp diode. The current pulse for saturating the reactor at turn-on is preferably derived from a shunt snubber charging pulse or from an external generator synchronized to the turn-off time of a power switching device in the switching circuit.

Abstract: In order to correct non-linearities inherently existing in the relation between the value of a hydraulic fluid parameter controlled by a proportional valve and an operating signal controlling the valve, in an arrangement in which the setting of the valve is controlled by effecting a comparison between the operating signal and a feedback signal representing the valve movement, a memory is provided to modify one of those signals prior to comparison in a manner to compensate for such non-linearities.

Abstract: A fan motor sequencing switch assembly is employed to effect delayed full power energization of a magnetron in a microwave oven for protecting the magnetron and energization circuit therefor against high start-up current surge and for cooling the magnetron during oven operation. The sequencing switch is connected in parallel with a start circuit consisting of a start switch and serially connected current limiting resistor, and is operated by an actuator movable by the magnetic field induced in the fan motor upon energization, the motor being connected to the start switch and sequencing switch for energization through either switch.

Abstract: For use in an electronic printing system having a serial impact printer, apparatus is provided to accurately control the velocity of the print hammer during printing and provide accurately controlled impact energy, which is proportional to the character face area. The apparatus includes a servo feedback system where the primary driver for the print hammer is a moving coil in a magnetic field, and the velocity sensing required for the servo feedback loop is the back emf in the moving coil with the back emf being proportional to the hammer velocity.

Abstract: A fuel injection system includes a pump including a pump plunger and electromagnetic means for actuating the plunger against the action of a spring. The electromagnetic means includes a winding which is energized to cause delivery of fuel. First electronic means is provided to cause energization of the winding when delivery of fuel is required and second electronic means operable to cause de-energization of the winding. The second electronic means includes a comparator which receives a required fuel signal and a signal from a transducer which provides a signal representative of the plunger position. When the predetermined movement of the plunger has taken place the winding is de-energized to allow the plunger to return under the action of the spring.

Abstract: An apparatus is proposed for controlling the de-excitation time of electromagnetic devices, in particular electromagnetic injection valves in internal combustion engines, wherein a switch (or an actuation circuit in general) is disposed in series with the device, characterized in that a circuit arrangement with a controllable output potential is disposed in series or in parallel with the electromagnetic device. It is the purpose of the apparatus to linearize the current decrease through the electromagnetic device after the end of the actuation pulse and preferably to simultaneously control its rate of decrease. As a result, control of the de-excitation time of the particular electromagnetic device is attained. In terms of function, the circuit arrangement represents a controllable Zener diode.

Abstract: Residual magnetism in the engageable members of an electromagnetic clutch is relieved following deenergization of the clutch coil by charging a capacitor with the inductive energy stored in the coil at deenergization thereof and subsequently discharging the capacitor into the coil in a direction opposite to that applied to the coil during energization.

Abstract: A circuit for controlling operation of an electromagnet includes a source of voltage connectable to the electromagnet to produce current flow in one direction and develop a magnetic force therein. A dissipating circuit is connectable to the electromagnet to form a closed loop and has impedance means for dissipating stored energy with gate means between the closed loop and the source producing current flow from the source through the closed loop when the residual potential drops to the potential of source and produce reverse current flow through the magnet. The circuit also has a reverse current limiting means in parallel with the impedance means and includes a manually variable resistor to adjust the limit of reverse current flow.

Abstract: An electrical circuit for driving an inductive load includes an output transistor of one conductivity type and a detector transistor of the other conductivity type. The output transistor has an emitter connected to a power source, a base to which an input signal is supplied, and a collector connected to one end of an inductive load. The detector transistor has an emitter connected to the collector of the output transistor, a base connected to the other end of the inductive load, and a collector connected to the base of the output transistor. When the output transistor is rendered nonconductive, high counter electromotive force is induced between both ends of the inductive load. Thereby the detector transistor turns on and the output transistor is rendered conductive again.

Abstract: The present invention is directed to an operation detecting device of a camera for detecting the operation of an operation member such as the shutter member. The operation detecting device functions by detecting the electrical signal produced at the time at which a closed magnetic circuit is opened when a magnet operates so as to actuate or release the operation member.

Abstract: A method and apparatus for controlling electric current in loads that are essentially inductive, such that sparking and "ringing" current problems are reduced or eliminated. The circuit apparatus employs a pair of solid state switches (each of which switch may be an array of connected or parallel solid state switching devices such as transistors) and means for controlling those switches such that a power supply supplying two d.c. voltages (e.g. positive 150 volts d.c. and negative 150 volts d.c.) at low resistance may be connected across an essentially inductive load (e.g. a 6 gauge wire loop one hundred meters in diameter) alternatively and such that the first solid state switch is turned off and the second is turned on such that both are not on at the same time but the first turned on and the other on in less time than the inductive time constant (L/R) so that the load is essentially always presented with a low resistance path across its input.

Abstract: An improved circuit for energizing and quickly deenergizing the DC operating winding of an electromagnetic relay or contactor from sources of AC supply. It employs a full wave rectifier bridge, a transistor for initiating and maintaining the energization of the relay or contactor control winding when AC is supplied to the bridge, and a zener diode connected in parallel with the main conducting path of the transistor to facilitate quick deenergization of the control winding when the AC supply to the bridge is interrupted.

Abstract: An engergizing circuit for a solenoid valve has a power source connected to a solenoid coil of the solenoid valve through on-off contacts. The energizing circuit includes a capacitor and a solid-state surge absorber which are respectively connected in parallel with the solenoid coil, and the surge absorber is made from a sintered material containing a metal oxide as a principal component and having a non-linear electric resistance characteristic with respect to the applied voltage. By virtue of the solenoid valve energizing circuit constructed as described, when the on-off contacts are separated, the occurrence of an arc between the contacts thus preventing wear of the contacts, while when the solenoid coil is deenergized, the delay time in the return movement of the valve spool is decreased, and moreover the surge voltage produced across the ends of the solenoid coil upon its deenergization is controlled to a predetermined low voltage.

Abstract: A driver mechanism for a dot matrix printhead, including an electromagnet, an armature, and a print impact element connected to the armature by a cantilever spring, energization of the electromagnet and consequent movement of the armature to closed position driving the impact element to impact a record sheet supported on a platen; a concentrated mass load is mounted on the spring, sufficient to maintain the impact element essentially in its rest position during a substantial portion of the armature movement so that the force/travel characteristic of the spring governs movement of the impact element, with maximum force at the outset and near zero or zero force at impact. Energization of the electromagnet is interrupted when the armature closes, and a shunt circuit holds the armature closed until just before impact.

Abstract: A circuit arrangement for driving saw-tooth current through a coil comprising a trace capacitor and a retrace capacitor, connected in a closed loop with said coil, a current recovery diode connected in parallel with the said retrace condenser, a first controllable switch, having a control electrode operative to receive periodic control signals to render the said first switch conductive during part of the trace interval, and an inductance connecting the said first switch to a power supply source in which energy is stored during the interval in which the said first switch is conductive and from which energy is supplied to the said first retrace capacitor by way of a second diode and a third capacitor when the said first switch is not conductive, the energy stored in the said third capacitor when the said first switch is not conductive, being restored to the supply source when the said first switch is conductive by way of a second controllable switch.

Abstract: A first amplifier measures the instantaneous voltage across a resistor, connected in series with the electromagnet of a solenoid valve, as the current increases following energization of the electromagnet. A second amplifier measures the same voltage and stores the peak value in a capacitor. The two measured voltages are applied to a comparator which detects the difference, and generates an output, when operation of the electromagnet armature causes a transient reduction in the resistor voltage. Initial energization of the electromagnet sets a memory and starts a monostable timing period. The set output of the memory primes one input of an AND gate, the second input being inhibited by the monostable output during timing. If the electromagnet armature operates normally, the comparator output resets the memory and removes the AND gate priming signal prior to completion of the timing period.

Abstract: The disclose circuit energizes a magnetic winding of a shutter actuating device. A constant voltage circuit is connected across the magnetic winding, or between the power supply terminal of the magnetic winding and a basic potential to ensure that the response of the armature of the actuating device to the output of a timing circuit is stabilized despite variation in the voltage of an electrical power source. This produces the advantage of substantially improving the accuracy of exposure control, because the closing operation of the shutter is controlled through movement of the armature.

Abstract: A protective circuit for an electronic switching amplifier is controlled by an operating switch, the amplifier serving to turn on an electromagnet with timed pulses during its operating interval. The electromagnet may electromagnetically actuate positioning and actuating elements on sewing machines and the like, with the timed pulses. A cutoff voltage limiting circuit is connected on one side between the electromagnet and the switching amplifier. A free-running diode is connected in parallel with the electromagnet through an electronic switch as an additional cutoff voltage limiting circuit. The electronic switch is caused to conduct by the switching amplifier during the operating interval, at least during the decay of the timing pulses. The electronic switch is blocked when the operating interval is terminated by the operating switch. The cutoff voltage limiting circuit is designed to conduct when electronic switch is blocked.

Abstract: An electromagnetic damping mechanism for a force motor comprising a drive coil, a damping coil, and static coils located about the drive and damping coils to offset the self-induction occurring in the two coils, so that a voltage proportional to the velocity of motion can be induced in the damping coil.

Abstract: The circuit utilizes a tertiary transformer for coupling a driving current to an inductive load. A switching transistor in series with the primary winding of the tertiary transformer initiates current flow thru the primary winding, which current, in turn, induces a current in the secondary winding of the tertiary transformer. The inductive load is connected across the secondary winding. The tertiary winding of the transformer is serially connected by a back-biased diode between the driving power source and a reference potential so as to quickly dissipate the energy stored in the secondary winding and the inductive load back to the driving power source when current in the primary winding ceases.

Abstract: An improved supply circuit for electromagnets. The supply circuit comprises a bridge rectifier, an attracting winding positioned in the diagonal of the bridge rectifier, a holding winding placed on the magnetic circuit of the electromagnet, and an isolating contact which isolates the bridge at the end of the pulling-in course of the movable member of the magnetic circuit. The holding winding being connected in parallel across the system formed by the isolating contact and the bridge rectifier.

Abstract: A switching device for the indirect activation and/or termination of systems operatively coupled to the switching device which includes an inductor adapted to be periodically pulse energized, an armature movably mounted with respect to said inductor so as to assume a first and a second position relative to the inductor thereby causing a distinct variation of current flow in the inductor when energized by a periodically applied pulse, a manipulative armature positioning means and an associated electrical circuit responsive to current flowing in said inductor. The members are arranged such that the circuit is adapted to selectively indirectly actuate an external system only when said armature assumes one of said positions and a periodic energizing pulse has reached the inductor.

Abstract: A solid state switching circuit for applying rectified alternating current to one or the other of two solenoid valve actuators and modulating that current from a pull-in value to a lower holding value has a separate power circuit for each solenoid and a common timing and trigger circuit. Each power circuit contains a pair of diodes and a pair of silicon controlled rectifiers connected in a bridge circuit to supply its solenoid. The common timing and triggering circuit is connected to be energized whenever either power circuit is energized and contains a first DIAC control circuit for supplying triggering pulses early in each AC cycle and a second DIAC circuit for supplying pulses late in each AC cycle. The DIACs feed a coupling transformer which is coupled to the silicon controlled rectifiers of both power circuits. A time delay circuit biases a transistor to the on state after a predetermined time interval to disable the first DIAC control circuit.

Abstract: A photographic camera shutter is moved to open and returned to its closed position by electromagnetic actuating means. A special electronic circuit is connected with said actuating means to energize the electromagnetic device with sufficient potential to cause a smooth and rapid opening movement which then decreases to a lower potential during the time interval that the shutter is to be maintained in its open position.