Abstract: A PLL motor controller in accordance with the present invention comprises a driving system for driving a motor, a reference frequency generator for generating pulses with reference frequency that corresponds to the speed of motor rotation to be set, a counter which is run freely at the reference frequency from the reference frequency generator, a pulse generator for generating sampling pulses with a timing that responds to the actual rotation speed of the motor based on the pickup signal from the driving system, a latch circuit for latching a digital information in the counter at the timing of sending the sampling pulses from the pulse generator, and a D/A converter for analog-converting the digital information in the counter that is latched and for supplying the result to the driving system. The driving system is constructed so as to drive the motor to be rotated with a set speed of rotation according to the error signal from the D/A converter.

Abstract: There is disclosed a monostable multivibrator in which a latch circuit or flip-flop circuit and a comparator circuit are separated. The comparator circuit compares a reference potential and an output potential of a time constant circuit and produces an output signal. The flip-flop circuit is controlled in accordance with an output signal of the comparator circuit.