device 3 provide a means for controlling an ac motor to make repeatable discrete positional changes in either direction for any mechanical mechanism where a motor can be installed independent of any amount of backlash or loss motion in the mechanism or in the coupling between the motor and mechanical input to the mechanism 4 provide for automatic centering for each motorized mechanism that can be actuated at the beginning of each job to prevent running into mechanical stops 5 provide 1 through 4 to control single or multiple motors simultaneously 6 provide the utmost in simplicity to minimize the cost of installation and the need for operator training the following list details some of the advantages possible in some of the preferred embodiments of the present invention 1 by controlling motor activation time electronically significantly higher and significantly consistent resolutions and slew rates can be achieved 2 the present invention provides the capability of using low cost ac induction motors with far greater tolerance of friction and inertial loads greater flexibility and selection of motor power and gearbox ratios 3 accurate and repeatable position changes are made each time a switch is first pressed and then released the time interval for correction is set in integers 120 cycles per second 4 the low pass filter inherent in the ac induction motor due to armature inertia provides automatic gain reduction with time thus providing a much greater dynamic range with increased accuracy and speed of response over synchronous motors 6 repeatable positional changes can be made in both directions that are far smaller than the backlash or loss motion in the.