Rotational pulse generating circuit for commutator DC motors

摘要

A rotational pulse signal generating circuit (3) for a commutator DC motor (11) is made up of a filter device (30) for eliminating noise from the motor, a cutoff frequency of the filter device being variable depending on an external signal; a pulse shaping device (3b) for generating a ripple pulse (f) indicative of a rotational number of the motor by wave-shaping an output of the filter device; and a clock generating device (3c) for generating a clock signal on the basis of the ripple pulse and a rotational condition signal of the motor, the clock signal (fCLK) being fed to the filter device for making the cutoff signal thereof variable. <IMAGE>