Abstract: A device for controlling the speed of a d.c. motor (M) employs a method in which the motor supply voltage (V) is controlled by a control voltage (Vo) supplied by a comparator circuit (11) which compares a reference signal (S.sub.ref) with a signal (S.sub.V) representing the motor speed. The signal (S.sub.V) is derived from a signal (S.sub.M) induced by the motor rotation via a signal processing circuit (21). The motor supply voltage (V) is controlled by the control voltage (V.sub.o) by means of a negative resistance circuit (31) (-R), which at least partly compensates for the internal resistance (r) of the motor.

Abstract: An integrated circuit regulator in which current regulation is effected by means of a current mirror utilizing motor current as an input. The base currents of the transistors of this current mirror are supplied by a second current mirror whose operation depends on that of the first one. The device is used for speed control in battery-operated motors for record players and recorders.