Speed setting arrangement for sewing machines

摘要

A speed setting arrangement for a sewing machine comprises a permanent magnet mounted for unitary rotation with the foot pedal of the sewing machine, and a magnetic sensor including a plurality of magnetoresistors arranged in pairs to form a bridge circuit on a stationary plane spaced a distance from the plane of rotation of the magnet. The magnetic sensor provides an output signal which is exclusively a function of the magnetic orientation of the magnet and thus serves as a valid indication of the amount of pedal depression. An analog to digital converter is coupled to the magnetic sensor to convert its output into a digital signal for speed control purposes.