Hall sensor is an integrated sensor based on Hall effect, which is composed of Hall element and its affiliated circuit. As one of the three major sensors, Hall sensor is widely used in industrial automation technology. It is widely used in industrial production, transportation and daily life. The Hall effect is a type of magnetoelectric effect, which was discovered by A.H.Hall (1855-1938) in 1879 when he studied the conductive mechanism of metals. There is A Hall semiconductor chip in the magnetic field, and a constant current I passes through the chip from A to B. Under the action of the Lorentz force, the electron flow of I is shifted to one side as it passes through the Hall semiconductor, causing a potential difference in the direction of CD, called the Hall voltage.

The Hall voltage varies with the magnetic field strength. The stronger the magnetic field, the higher the voltage, the weaker the magnetic field, the lower the voltage. Hall voltage is very small, usually only a few millivolts. However, it can be amplified enough by an amplifier in an integrated circuit to output a strong signal. If the Hall IC plays a sensing role, it must mechanically change the magnetic induction intensity. The method shown below uses a rotating impeller as a switch to control the magnetic flux. When the impeller blade is located in the air gap between the magnet and the Hall IC, the magnetic field deviates from the IC and the Hall voltage disappears. In this way, the change in the output voltage of the Hall IC can indicate a certain position of the impeller drive shaft. Using this working principle, the Hall IC chip can be used as an ignition timing sensor. A Hall effect sensor is a passive sensor that can only operate on an external power source, a feature that enables it to detect low-speed operation.