Abstract: Disclosed herein is a system for applying a power-supply voltage to the voice coil control circuit provided in a disk drive and designed to drive the head actuator provided in the disk drive. The power supply circuit of the disk drive outputs a voltage that corresponds to the power-supply voltage applied from a host system. A voltage step-up circuit is provided, which increases the output voltage of the power supply circuit. A switching circuit is provided, which selects the increased voltage output from the voltage step-up circuit when a large current needs to be supplied to the voice coil motor incorporated in the disk drive. The switching circuit selects the output voltage of the power supply circuit when a relatively small current needs to be supplied to the voice coil motor.

Abstract: There have been cases wherein the program itself does not operate normally and only continues to output the monitoring pulse so that racing cannot be detected, or due to electromagnetic waves or noise a pulse signal being outputted normally is measured erroneously and a mis-detection is made. In a control apparatus of an electric power steering system for, on the basis of a current command value computed from a current detected value of a motor and a steering assist command value computed on the basis of a steering torque arising in a steering shaft, controlling the motor, which applies a steering assist force to a steering mechanism, a control apparatus of an electric power steering system characterized in that it comprises a first control part and a second control part each inputting at least a torque signal, a vehicle speed signal, the motor current detected value and a motor terminal voltage, and the motor is controlled with the first control part and the second control part.

Abstract: A circuit and method are disclosed for determining whether a brushless polyphase motor is spinning in a reverse direction relative to spin direction during normal operation. The circuit receives a back emf signal of a first phase line and determines a polarity of the back emf signal following a back emf signal associated with a second phase line crossing a zero reference level. Based upon the determined polarity of the back emf signal of the first phase line, the circuit selectively asserts an output signal indicating that the motor is spinning in the reverse direction.

Abstract: A method for controlling an electromagnetic actuator having an arm connected thereto uses a circuit that temporarily places in a high impedance state output nodes connected to a winding of the electromagnetic actuator. A detected BEMF is compared with a lower threshold and an upper threshold. Current in the electromagnetic actuator is monitored and controlled. A current pulse is provided to the electromagnetic actuator based upon the comparison of the detected BEMF with the lower and upper thresholds. The respective amplitudes of successively provided current pulses having a same polarity are progressively increased, and an amplitude of a provided current pulse having a polarity opposite a polarity of a preceding current pulse is decreased. The amplitude of the driving current pulses provided to the winding of the electromagnetic actuator advantageously adapts automatically to varying frictional conditions, or to any other cause of variation of the mechanical load of the actuator.

Abstract: A squeeze protection system for movable parts of a vehicle, includes an operating switch for one or several parts to be moved, one or several actuators assigned to the operating switch, a control device for the actuator or the actuators which receives a signal from the operating switch, and a device for determining an irregularity during the movement of the movable part which device is coupled with the control device. In order to ensure a secure closing of the movable part also in the event of an operating disturbance, it is provided that, when the operating switch is activated and an irregularity is detected during the movement of the movable part, the movement is first interrupted and is then continued at a higher switch-off threshold.

Abstract: The present invention relates to method and apparatus for finding the digital value requiring to drive a motor of an optical disk device and applying a driving voltage according to the digital value to the motor. The method according to the present invention digitize an analog constant reference voltage using a supplied operating voltage varying within a predetermined range, determines the current value of the supplied operating voltage based upon the digitized value, calculates a digital control voltage for a given driving voltage so that the calculated voltage may have different value according to the determined current value, and applies a driving voltage corresponding to the calculated digital control voltage to a motor for moving an optical pickup.

Abstract: A method and circuit for operating a polyphase dc motor in which discontinuous sinusoidal drive voltages are applied to the windings of the motor in predetermined phases. The discontinuous portion of the sinusoid is timed with the bemf zero crossings. Bemf zero crossings are detected, and phases of the drive voltages are adjusted to have zero crossings substantially in the discontinuities of the drive voltages. The method and circuit result in motor operation with significantly reduced acoustic motor noise.

Abstract: A method and a circuit for switching a motor controller from pulse width modulation to linear control for a brush-less, sensor-less, poly-phase DC motor. The method includes steps of operating a drive circuit for a poly-phase direct current motor in a pulse width modulation mode and determining that a zero crossing will occur within a predetermined interval. The method also includes steps of enabling a bias current to a transconductance operational amplifier and changing an operating state of the drive circuit from the pulse width modulation mode to a linear mode. The method further includes steps of determining that the zero crossing has occurred, disabling the bias current to the transconductance operational amplifier and changing the operating state of the drive circuit from the linear mode to the pulse width modulation mode.

Abstract: A voltage generation circuit (60, 62) is adapted to sense voltages on multiple windings (82, 84, 86) of a multi-phase brushless DC motor (22) during successive intervals of a rotation of the motor (22) in which the respective windings (82, 84, 86) are not being driven. The voltage generation circuit (60, 62) provides a different output voltage from the voltage used to drive the motor (22). In one embodiment, the voltage generation circuit (60, 62) includes a voltage boosting circuit (62) to increase the output voltage above the drive voltage. This voltage generation circuit (60, 62) may be advantageously combined with an electrically programmable read only memory (EPROM) (56) on a single integrated circuit chip. The voltage generation circuit (60, 62) generates the EPROM programming voltage without the need for a costly on-chip charge pump or off-chip DC-DC converter.

Abstract: A conventional method for driving a servo-motor carried out control by means of a current feedback loop, using a current sensor and an A/D converter; therefore, the number of parts was great, cost reduction was difficult and it was difficult to avoid control errors caused by errors in the precision of the current sensor.A method for driving a servo-motor of the present invention comprises detecting a power voltage (V) of a servo-motor (4), controlling a voltage command (Vcmd) to a power converter (3) by numeric calculation using a detected value (Vcc) of this power voltage (V), and controlling power of a drive current (Iu, Iv, Iw).

Abstract: A power down brake latch circuit for dynamically braking a spindle motor in a disk drive system is disclosed. The power down brake latch circuit includes a reservoir capacitor, a smoothing capacitor, a timing circuit, and a logic circuit. The timing circuit includes a voltage divider and a bandgap comparator. The smoothing capacitor absorbs a BEMF voltage from the spindle motor as it rotates after losing power. The timing circuit generates a first signal when a voltage on the smoothing capacitor falls below a threshold. The logic circuit brakes the spindle motor in response to the loss of power and the generation of the first signal.

Abstract: A method for restarting a motor of a submersible pump after a power interruption is disclosed. The system first detects when the power is turned back on to the system. A control means then samples signals sent back from the unpowered motor and determines the frequency and phase sequence of the signals. The speed and direction of operation of the motor are then determined from the determined frequency and phase sequence. A first pulse width modulation waveform is then applied to the motor matching the determined speed and direction of the motor. Finally, the output frequency of the waveform can be adjusted to adjust the speed and direction of operation of the motor until the motor reaches a desired speed and direction of operation.

Abstract: A pulse width of a drive pulse of a brushless motor is modulated in correspondence to a setting signal for setting the rotation rate. Switching control for the current supplied to exciting coils is implemented by using an output signal from Hall elements for detecting the position of the rotor and the drive pulse. Correction of the pulse width of the drive pulse is implemented to ensure that the average voltage is maintained at a constant level even when the source voltage fluctuates so that stable rotation can be maintained over the entire rotation rate range even when the source voltage supplied to the brushless motor fluctuates and so that the fuse can be prevented from melting and the motor can be prevented from becoming damaged, which may otherwise be caused by a fluctuating source voltage.

Abstract: The arrangement or apparatus for operating a magnetically suspended, electromotoric drive apparatus in the event of a mains disturbance comprises a drive converter feeding the drive apparatus, a driver feeding a magnetic bearing and a voltage converter, which are connected to a common intermediate circuit. The voltage converter feeds a stopping control apparatus and the drive converter can be switched to a regeneratively acting mode of operation by the stopping control apparatus in the event of a mains disturbance in order to provide at least the driver feeding the magnetic bearing and the stopping control apparatus with electrical energy via the intermediate circuit.

Abstract: A speed control apparatus for determining and controlling the speed of rotation of a rotor in an AC motor. The motor includes a stator having main and auxiliary windings. Main and auxiliary winding controllers control the operational input signals supplied to the main and auxiliary windings by a signal generator. A pulse generator is connected to the main winding for providing a test pulse during a speed measurement operation. The test pulse magnetizes a portion of the rotor which induces a feedback EMF signal in the auxiliary winding. A feedback sensor circuit receives the feedback signal and forwards it to a microprocessor. The microprocessor calculates the rotational speed of the rotor based on the feedback signal.

Abstract: The sensing of BEMF signals in the motor's windings for synchronizing the phase switchings, in driving a brushless and sensorless motor with predefined constant voltage or current values or predefined voltage or current profiles stored permanently in a memory, is greatly simplified through a reconstruction technique that avails itself of the knowledge of the predefined drive values. The sensing does not require access to the center star point and is performed by sensing either the voltage difference between the terminals of two windings or of the current flowing in two windings, depending on whether a current or voltage mode is employed.

Abstract: The present invention includes a circuit for detecting a back EMF signal for a motor. The circuit includes a circuit 200 for detecting when the back EMF signal from the motor is either a positive EMF signal or a negative EMF signal, a positive source circuit 302 to supply a positive current, a negative source circuit 304 to supply a negative current, a switch circuit 120 and 122 to connect the positive source circuit to an output circuit 410 of the back EMF signal circuit and to connect the negative source circuit to the output circuit, and the output circuit outputting the positive source current while the positive EMF signal is detected and outputting the negative current while the negative EMF signal is detected.

Abstract: Methods and apparatuses are provided to identify and extract a torque ripple signal found in the back-emf signal from an electric motor. The torque ripple signal is used in a feedback control loop to reduce the amount and effects of torque ripple in the motor and the motor system. A motor controller is provided to reduce torque ripple in an electric motor. The motor controller is suitable for controlling the speed or torque or other related parameters associated with the electric motor. A disc drive apparatus for use in information storage and retrieval systems is provided. The disc drive apparatus includes an electric motor, an information storage disc, and a motor controller. A method is provided for reducing the effects of torque ripple in an electric motor by sampling the back-emf signal generated by the electric motor, extracting the torque ripple signal from the back-emf signal, and generating an AC component signal proportional to the torque ripple signal.

Abstract: The rotational speed of a coasting induction motor is measured by sensing e residual electrical voltages at the power terminals of the motor, thus eliminating the need for conventional tachometer equipment, additional mechanical components or modifications to the induction motor itself. The power terminal voltage signal is detected and transformed into a DC voltage proportional to the frequency of the signal. This DC voltage can be input to the control system of a variable frequency motor controller to regulate the output characteristics thereof relative to the speed of the coasting motor.

Abstract: In one embodiment of the present invention, a "one-touch-up" power window system is provided for a motor vehicle. The system includes a controller which controls the power window motor. One function of the controller is to determine whether an obstruction impedes travel of the power window. The controller takes a plurality of samples of the electrical current drawn by the power window motor. If the last sample varies by more than a predetermined amount from any of the past samples taken over a predetermined distance of travel of the window, the controller concludes that an obstruction impedes the travel of the window. The controller then stops or reverses the power window motor to stop or reverse travel of the power window. In this embodiment of the present invention, distance of travel of the window can be inferred from rotations of the power window motor.

Abstract: A first method for detecting movement of an actuator includes supplying a demand current to a voice coil motor of the actuator (A.sub.1), sampling a voice coil motor voltage (B.sub.1), performing a slope detection of a voice coil motor voltage function (C.sub.1) and extrapolating the voice coil motor function (D.sub.1) to identify a change in slope of the voice coil motor function.A second method for detecting movement of an actuator includes supplying a continuously increasing current ramp to the voice coil motor of an actuator (A.sub.2), measuring a back e.m.f. voltage of the voice coil motor (B.sub.2), performing a change in slope detection of a back e.m.f. voltage function (C.sub.2) and integrating the back e.m.f. voltage function (D.sub.2) to determine movement of the actuator.

Abstract: An electric control for gas furnaces which controls a two speed main blower fan and an induction draft fan based on inputs from a room thermostat, a high limit and an ignition control including a gas valve. The control has a circuit board having a power supply for providing 24 volts DC current source to drive DC relays and a 5 volt DC power source to power a microprocessor. 24 volt AC input signals are coupled to the input ports of the microprocessor through current limiting resistors and to AC ground through pull down resistors. AC ground is also connected to the IRQ port of the microprocessor. The output ports of the microprocessor are connected to a relay driver which in turn is connected to the relays. Several breakaway tabs in the board provide optional features such as eliminating a normally provided draft delay timing function. Test pads are provided on the board so that the board can be tested during manufacture.

Abstract: An electric power steering apparatus in which the steering force of a steering wheel is assisted by an electric motor is disclosed. The number of revolution of the electric motor is detected, and the counter electromotive force of the electric motor is calculated on the basis of the detected number of revolution. A voltage which is to be applied to the electric motor and corresponds to the driving current instruction value determined in accordance with the steering torque is corrected on the basis of the calculated counter electromotive force. In the electric power steering apparatus, the period of the detection of the number of revolution of the electric motor is made longer than the period of the feedback control of the driving current of the electric motor, and the period of the feedback control of the driving current of the electric motor is synchronized with the period of the correction of the voltage to be applied.

Abstract: The present invention relates to a power source regenerative apparatus which prevents distortion of a voltage regenerating in the power source from being caused. An inverter transforms induction electromotive force caused in regenerating the power source, namely in decelerating the motor, into a direct current. A timing adjusting device outputs a regenerative signal ST at a predetermined timing before the potential of one phase indicative of the maximum potential in three-phase supply voltages becomes the same potential as that of another phase. Based on the regenerative signal ST, a converter converts the transformed direct current into an alternating current, and regenerates it to the power source.

Abstract: The invention provides a motor drive unit for use in conjunction with an atherectomy device which limits the torque exerted on a drive cable for rotating a cutting blade in the device. In a preferred embodiment, a motor drive unit includes a motor having a shaft coupled to the drive cable for rotating the cutting blade, a power supply coupled to the motor and a switch for selectively connecting the power supply to the motor. A torque control circuit connected to the power supply and the motor controls the torque exerted by the motor when the switch is closed, whereby the current to the motor is continuously increased from zero to a start-up level, the start-up level being the minimum current sufficient to turn the cutting blade.

Abstract: A method for starting spin-up of a spindle motor in a hard disk drive. When power is initially applied to the spindle motor, the spindle motor is set to a first commutation state. The spindle motor is maintained in this first commutation state for a pre-determined period of time to allow the spindle motor to reach a known null point. Thereupon, the spindle motor is advanced to a second commutation state. The spindle motor is then maintained at this second commutation state for another pre-determined period of time. Finally, the spindle motor is advanced two successive commutation states to a peak torque curve. Once the spindle motor has started spinning, the commutation process is controlled according to the sensed back EMF voltage being generated in the off-phase.

Abstract: An apparatus and method controls the speed of an AC induction motor by varying the frequency and current to the motor from an inverter power supply. A Counter EMF regulator receives a reference signal corresponding to the desired speed, and a signal proportional to CEMF for feedback. The output of the CEMF regulator is provided to the power supply to control the current to the motor. The CEMF feedback signal is also utilized to vary the output frequency of the power supply in accordance with the magnitude of the CEMF. This maintains the magnetizing component of stator winding current at a constant value for all operating frequencies of the motor. A signal corresponding to the load current component of the stator winding adds to the speed reference signal to the CEMF regulator to increase CEMF and frequency with increasing load, thereby to compensate for increased slip and maintain constant speed. The phase displacement between CEMF and stator winding current is determined.

Abstract: A control device for a film or tape transport comprises a control knob having a spindle which forms the rotor of an electric motor. The control knob is spun by the operator to generate a drive signal to advance or retard the film or tape driven by the transport system at a speed dependent on the speed of rotation. The rotational speed is sensed and a signal dependent thereupon is produced by a speed detector to control a servo-loop which drives the electric motor. The motor drives the control knob at substantially the same speed imparted by the operator without any further input by the operator. The control knob continues to be driven at this speed until the operator manually accelerates or decelerates the control knob.

Abstract: A circuit configuration for limiting the cutoff voltage occurring in controlling a servomotor (M) by means of width-modulated DC pulses comprises a power transistor (T2) which, via a capacitor (C) is connected through for a short time when a cutoff voltage appears thus limiting the cutoff voltage. Subsequently the transistor (T2) presents a high impedance. As a result a short-circuiting of the servomotor (M) will be prevented in the phase in which a spring force resets the servomotor into its zero position.

Abstract: A moving fader system, primarily for the processing and combining of audio signals, includes a dedicated preprocessor to implement the execution of repetitious input instructions. Other features contributing to the operation of the system include (1) "Look-up Tables" included in the preprocessor for conversion purposes, (2) a fiberoptic link for transmission of digital signals between the preprocessor and the servo circuits associated with each fader assembly, and (3) circuitry for combining the outputs of a position digital-to-analog (D/A) converter, an offset correction D/A converter and a gain correction D/A converter, to provide accurate analog servo signals to each fader assembly.

Abstract: An electronic safety circuit for a portable gas heater includes a transformer and half wave rectifier connected in parallel with a fan motor for charging a capacitor, and a solid state switching circuit, which may be either a pair of cascaded transistors, an SCR, or a Darlington switch, for applying a reverse polarity voltage across the solenoid of a solenoid operated gas valve to immediately turn off the gas valve in the event of loss of power to the combustion fan motor. The electronic safety circuit may be conveniently mounted on a PC board and enclosed in the combustion fan motor.

Abstract: An electric control for gas furnaces which controls a two speed main blower fan and an induction draft fan based on inputs from a room thermostat, a high limit and an ignition control including a gas valve. The control has a circuit board having a power supply for providing 24 volts DC current source to drive DC relays and a 5 volt DC power source to power a microprocessor. 24 volt AC input signals are coupled to the input ports of the microprocessor through current limiting resistors and to AC ground through pull down resistors. AC ground is also connected to the IRQ port of the microprocessor. The output ports of the microprocessor are connected to a relay driver which in turn is connected to the relays. Several breakaway tabs in the board provide optional features such as eliminating a normally provided draft delay timing function. Test pads are provided on the board so that the board can be tested during manufacture.

Abstract: A generating device of a phase current instruction value for an A.C. servomotor and the generating method thereof, drives a synchronous A.C. servomotor. A sine wave, namely, a phase current instruction value for commutation of the A.C. servomotor driver can be generated by receiving as an interrupt the detection signal of a commutation sensor which detects the reverse electromotive force of the a motor at the microprocessor. The pulse position of the present since wave is.The pulse position of present sine wave is determined by the interrupt signal of the microprocessor. The motor is driven and controlled by converting by way of a D-A converter to an analog signal the data for generating a sine wave according to the increase or decrease of an encoder pulse.

Abstract: An automatic vertical blind controller with memory, particularly an automatic vertical blind controller with automatic/manual operated memory for control of vertical blind turning and movement automatically by referring to a reference data in the memory representing the upper limit degree of turning/movement set up by its user, comprising an outer casing, an inner casing and a control circuit board, in which the control circuit board is composed of an infrared receiver circuit, a manual operated push button control circuit, a single-chip microprocessor, two relay motor driving circuits, a music control circuit, and a power supply; the inner casing is incorporated with two d.c.

Abstract: A direct current motor driving device for driving a direct current motor having a plus terminal and a minus terminal, which comprises a direct current source having a plus terminal and a minus terminal, the plus terminal being connected to the plus terminal of the direct current motor, pulse generating device for generating a pulse signal when an input signal to an input terminal of the pulse generating device exceeds a set threshold value, driving device for driving the direct current motor in response to the pulse signal outputted by the pulse generating means, and a first resistance type voltage dividing circuit inserted between the minus terminal of the direct current source and a minus terminal of the direct current motor for providing as the input signal to the pulse generating device a voltage signal produced by resistance-dividing a voltage between these terminals in a first ratio, whereby a counter electromotive force generated by the direct current motor by the rotation of the direct current motor b

Abstract: A DC power supply for a DC motor is controlled by a drive transistor. An "ON" state of the drive transistor is maintained by a comparator which compares a terminal voltage at a point between the DC motor and the drive transistor with a reference voltage supplied from the power supply. A clock pulse is applied to the drive transistor to make it periodically turn off in order to detect an induced voltage depending upon the rotation rate of the DC motor. The drive transistor returns to turn off upon stopping the rotating DC motor by force.A regulator is provided between the power supply and the reference voltage. A restraint torque and a rotation rate control means are also provided.Alternatively, a pulsating power supply is provided instead of the DC power supply and the clock.

Abstract: An apparatus for controlling conditions in response to an operator input, the apparatus including a rotary knob coupled to the shaft of the rotor of a stepper motor having first and second stator windings, in quadrature, with each winding being center tap grounded to provide first and second winding portions for each winding. One pair of first winding portions are used for providing pulse inputs to a microprocessor on rotation of the knob, in either direction, via a pulse control system, with the microprocessor providing command signals to a braking control system, which includes a direct current power control source, which may be either a voltage or current control source. The power control source, in turn is in circuit relation with the pair of second winding portions.

Abstract: This invention relates to an inverse electromotive force eliminating device which protects a motor controller of a motor utilizing a MOS-FET by effectively eliminating the inverse electromotive force generated in a process for accelerating and decelerating a mobile device by utilizing an alternating current servo motor operated by applying the power supply of an inverter. A voltage, generated by an inverse electromotive force upon accelerating and decelerating of a motor in a state when the direct current required for circuit operation is supplied by power supply, increases at an input of an inverter. The voltage is detected by an inverse electromotive force detector and thereafter it is applied to an inverse electromotive force eliminator by utilizing a MOS-FET base driver so that the inverse electromotive force of motor is eliminated. Simultaneously, first and second indicators indicate whether the power supply is inputted and whether the inverse electromotive force is generated.

Abstract: Apparatus for inhibiting high torque created by the application of reverse voltage to a conventional motor with a field coil and armature operating in the opposite direction comprising a pair of drive resistors in series with the motor, a corresponding normally open contact connected in parallel to each respective drive resistor, an energizing coil corresponding to each contact, a timing circuit and an inhibitor circuit. During high speed forward operation, both coils are energized, closing both contacts, shorting out both drive resistors and maximizing motor voltage. When reverse operation is desired, a reverse voltage is applied across the armature, resetting the timing circuit and activating the inhibitor circuit. The inhibitor circuit will deenergize the coils, opening the contacts and remove the short across the drive resistors and thus reduce the reverse voltage being applied and permit gradual deacceleration.

Abstract: Method of controlling at least one electric motor on an offset printing machine by inputting a set point for the rotational speed, which comprises forming a set point for the rotational speed by means of a device for controlling the electric motor, and reducing the value of the set point as a function of a measured line voltage when the line voltage is inadequate.

Abstract: A protection circuit for the power transistor of an automotive motor control circuit. The protection circuit comprises a protection transistor, a resistor, and a Zener diode. The emitter-collector circuit of the protection transistor is connected in series with the resistor across the primary conduction path of the power transistor, with the resistor connected across the conduction control terminals of the power transistor. The Zener diode is connected in series with the emitter-base circuit of the protection transistor across the motor, with the Zener diode poled to oppose current flow through the emitter-base circuit. Transient inductive voltage generated across the motor upon removal of an externally applied control signal exceeds the reverse breakdown threshold of the Zener diode and biases the protection transistor conductive.

Abstract: A braking method for DC motor of the present invention is applied to a pulse-driven DC motor. A counter electromotive force of reverse polarity to driving pulses which is generated by induction at the winding of the DC motor is charged in a capacitor. The charged counter electromotive force is fed to the winding of the DC motor during the time that the driving pulses are not fed to the motor, so that plugging is applied to the DC motor. Thus, an external power source for plugging is not necessary, and power consumption is reduced and the construction of the braking circuit becomes very simple. Also, the driving period and the plugging period have a complementary relationship therebetween, thereby enabling the accurate controlling of the rotational speed of the DC motor with a very simple circuit.

Abstract: A filament tensioner for controlling the tension of filament or roving as it is wound onto an article includes means for sensing the tension in the filament as it is being transferred from a spool and means coupled to the tension sensing means for adjusting the output torque of a motor which drives the spool to in turn maintain the filament tension at a desired value. The tension sensing means includes a pivoted arm, a roller rotatably coupled to an end of the pivoted arm, the roller being engaged by the filament so that the pivoted arm is pivoted to a position determined by the tension in the filament and means for generating a position signal representing the position of the pivoted arm. In the preferred embodiment, the position signal is utilized by a pulse width modulated drive system to control the output torque of the motor.

Abstract: A control system for electrically powering from an external alternating-current power source a direct-current underwater hand-operated tool or light activated by a switch. The control system includes a relay for connecting and disconnecting the external AC power source to and from the system, a transformer connected to the relay for transforming the AC power to a desired lower voltage level, a converter connected to the transformer for converting the transformed AC to DC power, cables for supplying the DC power to the tool, and a control circuit for sensing the voltage level of the transformed AC power and in response to the sensed voltage level increasing beyond a predetermined safe level, causing the relay to disconnect the external AC power source from the system. The control includes a Zener diode for sensing the voltage level of the transformer AC power, and a transistor and an SCR for controlling the operation of the relay.

Abstract: A control unit for operating the motor of a motor driven headlamp carrier mechanism includes oscillator circuitry for generating a series of pulses for energizing the motor, voltage responsive means for sensing a motor counter-EMF related voltage as an indication of motor rotation, output circuitry for interrupting motor energization when the voltage responsive circuitry senses motor stall, and start circuitry for energizing the motor independent of the oscillator circuitry for a period of time sufficient to produce motor counter-EMF. Such control permits sensing of the engagement of the headlamp carrier with fixed mechanical stops without the use of position or torque limit switches.

Abstract: A motor apparatus includes a motor, a first circuit for sensing a back electromotive force of the motor to provide a first signal, a second circuit for sensing a rotation speed of the motor to provide a second signal, a third circuit responsive to the first and second signals to provide a third signal corresponding to the first and second signals, and a fourth circuit for feeding to the motor a drive current with a magnitude corresponding to the third signal.The motor and the first to fourth circuits jointly form a negative feedback loop for setting up a proportional relationship of the second signal to the product of rotation speed and output torque of the motor. The second circuit changes the second signal proportionally to the rotation speed of the motor.

Abstract: A motor control circuit for submersible pumps has features to prevent restarting while the electric motor is backspinning. The circuit includes a sensor for sensing the voltage produced by the residual magnetism in the rotor of the motor while it backspins. The voltage sensed is amplified, then rectified and compared with a reference voltage that is preset. The reference voltage corresponds to a voltage produced during backspinning at a selected maximum amount tolerable when restarting. The DC pulses are filtered to provide a corresponding voltage, then compared to the reference voltage. The control circuit is disabled from allowing a restart, either manual or automatic, when the corresponding voltage is greater than the reference voltage.

Abstract: A speed regulating circuit which regulates motor speed without the use of a speed feedback signal by adjusting the magnitude of motor current so as to maintain a predetermined relationship between motor voltage and current. A function generator generates a current reference signal as a function of motor terminal voltage. The relationship between terminal voltage and motor current is established by curve fitting of the motor volt-amp family of curves for constant motor speeds. The current reference signal controls a motor current control circuit, preferably a time ratio or chopper circuit in order to adjust motor current and to regulate motor speed. A closed loop current control loop is associated with the chopper circuit for adjusting motor current to the current reference value.

Abstract: Constant selected speed running of an electric motor, with a varying mechanical load, is achieved by intermittently pulsing the motor at full power and comparing the back EMF of the motor, between power pulses, with a selected speed voltage, to accordingly control application of the power pulses. A particular control circuit is disclosed which permits operation of a pocket-sized system, powered by a three cell battery, to achieve substantially constant speed, at normally varying loads, throughout a ten hour period, with back EMFs at selected values between 0.01 volt (motor barely turning) and 2.0 volts (high speed). The system is useful in a personal air sampler, used to monitor a workman's exposure to noxious ingredients of breathing air.

Abstract: A safety device for preventing the automatic restart of a motor upon restoration of power to the motor. This device, in its preferred embodiment, includes a thyristor switch, such as a triac, in one of the power leads to the motor which is triggered by energizaton of the motor. Upon deenergizaton of the motor, the thyristor switch switches to its non-conductive state thereby preventing automatic restarting of the motor upon restoration of the power. A selectively actuable, momentary run switch is provided to momentarily shunt out the thyristor switch so as to selectively permit the restart of the motor.