Abstract: An automobile fan controller comprises: a fluctuation signal generator for generating a fluctuation signal; a pulse-width-modulation circuit including a triangle generator for generating a triangle-waveform signal having a constant amplitude and a constant period, and a comparator connected to the fluctuation signal generator and the triangle generator, for comparing the fluctuation signal with the triangle-waveform signal, thereby producing a pulse signal having a pulse width variable dependent on the fluctuation signal; and a driver circuit, including a switching power transistor connected to the pulse-width-modulation circuit, a fan motor mounted on an automobile, and an air flow switching unit mounted on the automobile for energizing and de-energizing said fan motor with a variable pulse width in response to the pulse signal.

Abstract: A motor protection circuit which generates a signal having a value proportional to the magnitude of the input current of the motor and a motor speed signal having a value proportional to the difference between the rated motor speed and the actual motor speed. The motor speed signal is multiplied by the input motor current proportional signal to derive a product signal. The product signal is summed with the input motor current proportional signal to derive a sum signal. The sum signal is compared with respect to a preset level to determine if it is greater than a preset level. If it is greater than a preset level, the sum signal is coupled to the input of a voltage controlled oscillator which generates an output signal having a value proportional to the magnitude of the sum signal. The output of the voltage controlled oscillator is counted in an up/down counter and an output is gated when the total count reaches a predetermined level.

Abstract: In an overspeed protection system for a centrifuge apparatus of the type including a rotor driven by a drive motor, a transducer for providing a signal whose frequency is a function of the rotational speed of the centrifuge rotor, an oscillator for generating a reference signal having a predetermined frequency, means for mixing the rotational speed signal with the reference signal to provide a difference frequency signal, a filter coupled to the output of the mixing means for passing signals having frequencies below a predetermined frequency, and means coupled to the filter for disconnecting power to the drive motor in response to an output signal from the filter, there is disclosed an improvement comprising a frequency comparator responsive to the rotational speed signal and the reference signal for generating an overspeed signal when the frequency of the rotational speed signal exceeds the frequency of the reference signal, and means for combining the outputs of the filter and the frequency comparator at th

Abstract: A monitor for detecting the relative velocity between a moving body or surface and a fixed body or surface includes a sensor having an actuator member, such as a wheel having magnetic pole pieces embedded therein and mounted for rotation proportional to the relative velocity between the two bodies or surfaces, and a pick-up member such as a coil or inductor, mounted adjacent the actuator for producing an electrical signal in response thereto. An electric circuit is connected to the pick-up member to receive the electrical signals therefrom and produce a plurality of indication signals in response thereto, including indication signals corresponding to the relative velocity being at or below one or more predetermined levels. The monitor also includes a plurality of indicators connected to the circuit and responsive to the indication signals therefrom, such as lights or audible alarms.

Abstract: An apparatus for insuring that the rotational speed of a spindle on a machine is prevented from exceeding a selected programmed speed. The apparatus is comprised of means for continuously receiving pulsed signals indicative of the instantaneous rotational speed of the spindle over a timed cycle, wherein the cumulative signal within the receiving means at the end of each timed cycle is representative of the actual rotational speed of the spindle.

Abstract: A circuit for controlling the operation of a bi-directional motor. A motor energized to run in one direction is stopped by applying a reverse or braking current to its energizing field. When the motor is virtually stopped, means are provided to de-energize the motor to prevent the motor from reversing direction.

Abstract: Motor drive and servo systems particularly useful in high quality broadcast video tape recorders. A sine/cosine drive for a brushless DC motor permits high motor efficiency in a system adapted for use in a servo loop. A technique for phase locking a pair of frequency related phase locked control variable signals to a pair of frequency related reference signals, horizontal and vertical sync signals, for example, provides the advantages and precision of closed loop correction at widely variable correction rates. More accurate tape shuttling in a VTR is provided by running a DC motor in a phase locked loop as a synchronous motor and more accurate stopping of the tape is provided by comparing the capstan speed to ground in a closed loop. Improved tape tension control in the head area is provided by a pair of vacuum columns controlled by an error signal derived from the peak-to-peak tension error.