Abstract: A circuit for controlling the position of a driven member is disclosed which includes a control circuit for controlling the application of electrical power to a motor and a circuit element operable for generating position error signals corresponding to the position of the load which may in one embodiment constitute a rotor element of the motor. A comparator section is provided for comparing the position error signals with position reference signals and for generating control signals to effect rotation of the load in a desired direction. In one embodiment, the error signal is generated by a feedback loop including a potentiometer having a movable element coupled to the load or motor rotor, wherein the voltage magnitude of the error signal is varied in accordance with the rotational position of the load or rotor element. In a preferred embodiment, the comparator section includes first and second comparators respectively responsive to position deviations of the rotor in first and second rotational directions.

Abstract: A pair of simple phase-sensitive full-wave high-gain demodulator circuits generate an output for both halves of an AC reference cycle. One of the demodulator circuits is utilized as an amplifier to drive, for example, the steering system servo valve in an aircraft steering system and the other demodulator drives a dummy load which has a resistivity approximately equal to the resistivity of the servo valve coils. The output current from both demodulators are compared, for example, by an opto isolator or coupler which generates corrective and/or warning signals in case a system failure occurs. In one embodiment, the sensor output loop is maintained at a predetermined voltage level above ground so that an open circuit in the sensor loop is detected by additional sensing circuits.

Abstract: A precision motor speed control system where a reference generator produces pulses for each revolution of a dispenser shaft, the time between pulses is measured and compared to a preselected standard, a time greater than standard will generate a pulse causing a transistor circuit to apply an accelerating voltage to the motor, a time less than the standard will generate a pulse causing a transistor circuit to apply a decelerating voltage to the motor.

Abstract: A typical alternating current two phase servomotor has two windings displaced 90.degree.; these windings are normally identified as the reference winding and the control winding. Rotational direction and speed of the motor may be controlled by applying AC voltages of the proper waveform amplitude and phase relationship to these windings. When controlling the direction of rotation and speed of such alternating current servomotors in accordance with a DC error signal, pulse width modulation is utilized. The DC error signal is compared with a periodic varying function and its inverse to generate a series of pulses that are logically combined with a square wave and its complement during an enable period to generate a first and second series of pulses each having a width related to the magnitude of the error signal and coupled to energize the control winding of the alternating current servomotor. Similarly, a second periodic signal and its inverse are used to generate pulses for the reference winding.