Speed control for DC motor of battery operated razor - with pick=up generator voltage during pulse internal of chopped armature current for control

摘要

A speed control circuit for a dc motor with separate excitation. The armature current is chopped by a dc switch in series with the motor and a direct voltage source. The motor can be fitted to a battery operated electric razor. The circuit adapts the motor to varying loads keeping the speed constant. The generator voltage picked off from the separately excited motor (1) is measured during the pulse intervals of the pulsed armature current. It is used as a measure of the actual value of the speed. A signal is supplied to the control circuit of the d.c. switch (5).