Positioning drive

Positioning drive for a sewing machine including a variable speed coupling motor having a coupling-and-braking magnet system, and means coupled to said motor and to said sewing machine, respectively, for performing different sewing functions such as needle positioning, thread cutting, feed adjustment and the like, comprising an at least 8-bit microprocessor system provided with input connections which are connectable to a program data source, and output connections to said motor and to said functional means to control the sewing machine by controlling rotary speed and/or angular position of the motor, and to control the operation of said functional means according to said program data source, and further comprising a three-stage speed controller including a phase-locked loop system which generates digital output signals, said phase-locked loop system having first and second input means connectable to a desired-speed-value transmitter and to an actual-speed-value transmitter, respectively, and having output means connected to said magnet system for direct energizing by said digital signals said magnet system to effect rotary speed regulation and angular position control of said sewing machine.