Motor control circuit

A circuit for use in combination with a motor which is operable at a plurality of speeds, said circuit comprising:

• an oscillator which generates a first signal;
• an encoder which senses the speed of said motor and which generates a second signal which is indicative of said sensed speed;
• an error signal production circuit which receives said first and second signals, which compares said first and second signals, and which generates a third signal based upon said comparison;
• a pseudo-random signal generator which generates a pseudo-random signal;
• a wave shaper which receives said pseudo-random signal and which uses said received pseudo-random signal to produce a fourth signal;
• a comparator which receives said third and fourth signals, which compares said received third and fourth signals and, based upon said comparison, which generates fifth signal;
• and
• an electrical power supply circuit which is coupled to a source of electrical power and to said motor and which receives said fifth signal and which provides electrical power to said motor in accordance with said fifth signal.

A method for controlling the speed of a motor comprising the steps of:

• providing a desired speed;
• measuring the speed of said motor;
• creating an error value by comparing said measured speed with said desired speed;
• pseudo-randomly generating a plurality of signals;
• comparing said error value to one of said plurality of pseudo-randomly generated signals;
• and
• controlling said speed of said motor based upon said comparison between said error value and said one of said plurality of pseudo-randomly generated signals.