In a drive system for driving an electric motor at a given rotational speed, an electric power source drives the motor. A switching arrangement connected in series with the power source applies discontinuous pulses to the electric motor. A signaler coupled to the motor has an output corresponding to the rotational speed of the motor and actuates an oscillator which produces pulse signals in response thereto. A threshold circuit responds to the pulse signals and to the signal generator and controls the switching arrangement. According to another arrangement, a bistable multivibrator is coupled to the motor and produces an output corresponding to the speed of the motor. A trigger then triggers a monostable multivibrator that produces pulses having times related to the desired speed of the motor. An AND gate responds to the two multivibrators and sets a flip-flop which is reset in response to the bistable multivibrator so that the flip-flop can drive driving means coupled to the motor for controlling the speed of the motor.