This sensor, uses a Hall effect transducer, The Hall effect is a property exhibited by all conductors . In the Hall effect, a voltage is produced that is the cross product of the current and applied magnetic field (Lorentz force).

Hall devices give direction of the applied magnetic field: a south pole gives one polarity of signal, and a north pole gives the opposite polarity. Semiconductor Hall devices are utilized as magnetic sensors, and respond to the field which is perpendicular to the plane of the device. Hall voltages are typically very small, For example, silicon Hall sensors have signals on the order of a few microvolts per Gauss. Permalloy thin films respond to the field in the plane of the film. Furthermore, Permalloy gives the same signal with either polarity. Hall devices are linear over a wide range of several thousand Oersteds, whereas Permalloy response is highly nonlinear, and saturates at a low field value, perhaps 50 Oersteds. Hall shows essentially zero hysteresis, and Permalloy is anisotropic, with some directions exhibiting hysteresis, and other directions not.