Abstract: An electric motor incorporating an internally powered DC magnet armature. The motor includes a field winding powered from a DC source but polarity controlled to produce an advancing magnetic field. Power is delivered from a DC source to the field windings by current amplifiers. The amplifier input is controlled by the signals from an optical encoder sensor. The encoder sensor detects the passage of light coded segments on an optical encoder disc rotating with the armature. The relative position of the encoder sensor determines the direction of rotation. The power output of the motor is varied by a variable pulse length generator which converts the pulses from the encoder sensors into a train of pulses of variable length.