Abstract: The disclosed system utilizes digital electronic programming to establish the rotational or translational speed of a motor driven member. The desired speed can be selected by manipulating a set of digital switches. A stable oscillator is employed to generate a high frequency signal which is processed by frequency dividers to produce a modulaton frequency signal. The modulation frequency is supplied to an optical encoder having a rotary shaft adapted to be connected to a rotary member, the speed of which is to be controlled. The encoder is constructed and arranged to produce a phase variable output signal at the modulation frequency, the phase of such output signal being variable as a function of the shaft angle.