The magnetic field has a hall semiconductor sheet, the constant current I from A to B through the film.
Under the action of Lorentz force, the electron flow of I offsets to one side when passing through Hall Semiconductor, so that the chip produces potential difference in the direction of CD, which is called Hall voltage. Hall voltage changes with the intensity of the magnetic field, the stronger the magnetic field, the higher the voltage, the weaker the magnetic field, the lower the voltage. Hall voltage is small, usually only a few millivolts, but magnified by an amplifier in an integrated circuit, it can amplify the voltage enough to output a strong signal. Lepers Hall integrated Circuits play a sensing role and require mechanical methods to change the magnetic field strength. Using a rotating impeller as a switch to control magnetic flux, when the impeller blade is in the air gap between the magnet and the hall integrated circuit, the magnetic field deviates from the integrated sheet and the hall voltage disappears. In this way, the change of the output voltage of the hall integrated circuit can indicate a certain position of the impeller drive shaft, using this working principle, the hall integrated circuit chip can be used to ignite the timing sensor. The Hall effect sensor belongs to the passive sensor, which has to have an additional power supply to work, which makes it able to detect the operation of low rotational speed.