A Hall-voltage slope-activated sensor

摘要

A method of detecting the passing of magnetic of ferromagnetic articles past a magnetic-field-to-voltage transducer is shown. The transducer is arranged to generate a first signal proportional to the strength of the ambient magnitude field, and comprising positive and negative slopes and positive-going and negative-going peaks. The method comprises tracking the amplitude of said first signal; detecting times at which the amplitude of said first signal departs from the amplitude of a previous said peak by a predetermined amount; and generating a binary output signal which changes from one binary level to the other at each successive detected said time. The method may be implemented by a Hall sensor.