For the detection of gears, rack gears, and other ferrous targets such as tone wheels, bolt heads, steel pins, rotating wheels, or discs there are two different magnetic sensing technologies to choose from.
Hall Effect Gear Tooth Sensors with back biasing magnetic structures detect the changes in the internal magnetic field when the gear teeth or other ferrous targets pass by the sensor face and output a digital square wave pulse train.
Variable reluctance sensors use an internal coil, pole piece, and magnetic structure to generate a sine wave voltage output from passing gear teeth.