A Hall effect sensor is used for speed detection, proximity switching, positioning and current sensing applications. Hall Effect sensors are transducers which vary their output voltages in response to changes in a magnetic field. Hall effect sensors operate as analogue transducers for directly returning the voltage. When the magnetic field is known, its distance from the Hall plate can be determined, and using a group of Hall effect sensors the position of the magnet can be deduced. Hall Effect sensors are very commonly used to time the speed of shafts and wheels, for instance, internal combustion engine ignition timing or tachometers. They are also used in brushless DC electric motors for the detection of the position of the permanent magnet.