Abstract: In a motor-driving system, the motor speed is controlled by a feedback signal derived from the difference in frequency and phase between a manually adjustable variable frequency and a rotational speed indicating signal. Frequency deviation of the manually adjustable frequency from a standard frequency is detected to energize a visual indicating device to indicate the magnitude of the frequency deviation and hence the motor speed deviation from a setting level. The direction of the frequency deviation is detected to indicate whether the motor speed deviation is above or below the setting level. The variable frequency is manually adjusted to vary the motor speed by noting the visual indication until null indication is obtained.

Abstract: A circuit for mixing digital signals from two different signal sources which are applied to respective input terminals. The circuit includes a first bistable circuit and a second bistable circuit for mixing the two signals on a single time base and forming an output signal with an astable period of a length corresponding to several cycles of the signal applied at one input terminal and one cycle of the signal applied at the other input terminal.

Abstract: A speed control system for a d-c electric motor comprising a three-terminal space control IC to provide a constant voltage source having a negative internal resistance equal in absolute value to the internal resistance of the motor and thereby render the motor rotatable at a constant controlled speed. A resistance element having a positive temperature coefficient is used as an external circuit element for the IC so that rotation speed variations relative to load torque variations will be substantially constant despite variations in the ambient temperature.

Abstract: A revolution speed indicator arrangement is provided which includes a reference frequency oscillator, a tachogenerator for generating a frequency associated with a revolutional speed of the revolving body, difference frequency deriving circuitry interconnected to the reference frequency oscillator and the tachogenerator for deriving a difference frequency between the frequency associated with the revolutional speed and the reference frequency, and an indicator unit responsive to the difference frequency deriving circuitry for visually indicating the difference frequency. The arrangement may be provided with a coincidence determining unit responsive to the difference frequency for detecting coincidence between the frequency associated with the revolutional speed and the reference frequency, and the indicator unit is connected to the coincidence detecting unit to visually indicate the coincidence.

Abstract: A PNM (pulse number modulation) signal is generated in response to a DC signal the magnitude of which is in proportion to the detected rotational speed of an electric motor to regulate a period of time for which an electric power is fed to the motor by switching the electric power in accordance with the PNM signal. The switching frequency is arranged to vary depending on the variation of the load of the motor.

Abstract: An AC feedback circuit is interconnected through a choke coil between the input and output lines of a motor drive circuit so that negative feedback may be effected at a low frequency close to the cutoff frequency of the control system, and positive feedback may be effected at a high frequency. The carrier signal or the high frequency signal for controlling the switching may be generated within the drive circuit. Thus a switching type speed regulator which is simple in construction yet has high efficiency may be provided.

Abstract: A motor speed control system detects a rotation speed of a motor, compares a detected output signal with a reference voltage or a reference frequency to produce an error signal, produces a saw-tooth wave signal of an appropriate repetition frequency, compares the error signal with the saw-tooth wave signal to produce a switching signal, and drives a motor by the switching signal to control the speed of the motor. The system includes a first driver circuit for driving the motor by the output signal of a first comparator circuit which produces the error signal, and a second driver circuit for driving the motor by the output signal of a second comparator circuit which produces the switching signal. The motor is normally driven by the second driver circuit for speed control and is driven by the first driver circuit when the motor is started or overloaded or when the second driver circuit is defective.

Abstract: A velocity detecting apparatus comprises a waveform shaping circuit including a first stage switching transistor connected in a rotational speed control loop for a rotary machine, for amplifying and shaping an A.C. signal derived from a velocity sensor and being operated between a saturation region and an active region, a waveform transform circuit having a stable state and a quasi-stable state for a given period after the application of an input signal, for transforming an output signal of the waveform shaping circuit to a square wave having a given duration, an integration circuit for integrating the square wave with time to produce an integrated output, and a comparator for comparing the output voltage of the integration circuit with a reference voltage.

Abstract: Rotation of a rotary machine, e.g. a dc motor is controlled with higher accuracy by the system comprising a rotation speed detector for generating a signal having a repetition frequency dependent on the rotation speed of the rotary machine, a phase comparator having two input terminals one of which is applied with the output signal of the rotation speed detector, a voltage controlled oscillator applied with the output signal of the phase comparator, a frequency divider applied with the output of the voltage controlled oscillator and supplying the output to the other input terminal of said phase comparator, and a rotation speed controlling circuit having an input terminal applied with the output of the voltage controlled oscillator, i.e. a detection signal with a multiplied frequency.

Abstract: A step-to-impulse conversion circuit for converting a step input into an impulse output is disclosed which may eliminate the use of capacitors and comprises a combination of four transistors or three transistors, one thyristor and one diode with resistors so that the fabrication of monolithic integrated circuits may be much facilitated.

Abstract: An automatic speed control circuit for an electric motor is provided with a d.c. amplifier circuit having an output transistor of npn type. The motor is driven by a control signal supplied from the collector of the output transistor to control the motor speed. The collector of the output transistor is connected to one terminal of the electric motor, while another terminal of the motor and the emitter of the output transistor are respectively coupled to the positive and the negative terminals of a d.c. power source. The control signal supplied from the output transistor to the motor is changed in compliance with any variation of the power source. Therefore, the motor speed is independent of any variation of the power source.

Abstract: A circuit for producing an error voltage for a negative feedback loop for automatic control of a motor speed comprises a monostable multivibrator triggered by a feedback signal of a frequency representative of the motor speed for generating a rectangular signal of a predetermined pulse width, a pulse height proportional to a source voltage for the multivibrator, and a duty cycle decided by the frequency. A potentiometer-integrator derives a variable voltage proportional to an average of the rectangular signal voltage. A potential divider for the source voltage derives a reference voltage indicative of a desired motor speed. A comparator derives a difference between the variable and reference voltages as the error voltage.

Abstract: A first physical quantity derived from a detector coupled to a rotary machine is combined with a first reference physical quantity to produce a rectangular waveform signal with an amplitude which changes in response to the variation in supply voltage. The rectangular waveform signal is converted into a second physical quantity and is compared with a second reference physical quantity derived by the division of a supply voltage to produce control signals for rotating the rotary machine at a predetermined rate.

Abstract: In a constant speed regulator for a DC motor of the type in which the output of a generator mechanically coupled to a DC motor is converted into a square waveform output whose pulse duration or width is constant but whose duty cycle varies in response to the rotational speed of the DC motor, and the square waveform output is integrated so that the rotational speed of the DC motor may be controlled in response to the integrated output, an improvement comprising a series-circuit of a capacitor and a resistor connected between the output terminal of an integrator and the DC motor and a constant voltage circuit or a constant voltage regulating circuit shunting a DC power source, thereby eliminating the ripple component in the output of the integrator.

Abstract: A speed detector for use with a miniature DC motor is disclosed wherein a device such as coils or Hall generators for detecting the magnitude and direction of leakage flux are placed in opposed relationship with at least one pair of field poles of the DC motor, so that an output signal having a frequency proportional to an integral multiple of the number of slots of the armature may be derived.

Abstract: An electronic switch circuit and a pulse generator are connected in series between a positive and a negative power line. The switch circuit is, once triggered, rendered conductive and retains its conductive condition as long as left alone. The pulse generator automatically renders the conductive switch circuit non-conductive at a preset later time. An output can be derived in the form of a pulse from the pulse generator only while the switch circuit is conductive.