Abstract: The device for controlling the rotation speed of electric motors comprises an adjustable frequency generator (2) generating an output signal (s.sub.1) having a frequency which can be adjusted in relation to the desired speed (v.sub.d), a pulse generator (3) having a pre-determined period controlled by the adjustable frequency generator in such a way as to generate a control signal (s.sub.2) comprising a series of pulses at the adjustable frequency set by the frequency generator (2). The control signal (s.sub.2) is provided to a control unit (5) for the motor (6) whose rotation speed is to be controlled. The control unit thus provides a supply to the motor (6) corresponding to the control signal pulses. FIG. 1.