A full-wave adjustable motor speed control system with feedback for automatic regulation of the speed of an AC motor such as a series or universal motor. A bidirectional thyristor triode in series with the motor armature winding is controlled by a firing circuit operated by a ramp and pedestal voltage. The ramp may be set at a fixed value whereas the pedestal is adjusted for desired speed and regulated by a feedback signal. This feedback signal is developed in an amplifying feedback circuit that is adjusted to eliminate unwanted characteristics and to provide a true speed signal proportional to motor counter EMF.