# Application of Hall Sensor Ranging and Selection of Magnet

Cecelia Qiu 17 March 2022

We want to use the Hall sensor to measure micro-distance, and it is inevitable to involve the problem of Hall sensing distance. Some may require a relatively short sensing distance, such as 30 mm, but some may require a relatively long sensing distance, which may be several centimeters. So how do we reflect the moving distance through the Hall sensor? Now do the following introduction.

We all know that the principle of the Hall effect is to feedback the magnitude of the magnetic field through the output Hall voltage value. Then the relationship between distance and magnetic field strength, how to define the strength of the magnetic field. First of all, you need to use a magnet, but many people don't know how to choose the strength of the magnet? When we choose a magnet, the general magnetic field is 1-2 times larger than the Hall operating point you choose, so that the Hall element will sense the magnetic field and work. First of all, the size, thickness, shape, etc. of the magnet has nothing to do with the strength of the magnetic field. When choosing a magnet, choose a standard magnet and know the relationship between the strength of the magnetic field and the distance. The magnetic field lines of a magnet are in a divergent state. The farther the distance is, the weaker the magnetic field gradually becomes, showing a magnetic field gradient.

The sensing distance of the Hall is also directly related to the strength of the magnetic field. Generally, the sensing distance of the Hall is about 1CM. If the distance that needs to be sensed is relatively long, then it is necessary to increase the magnetic field or select a highly sensitive Hall element. The distance of sensing distance needs to be used together with the magnetic field and the Hall, or if your magnetic field is particularly strong, the Hall element with a slightly lower sensitivity may also be sensed. Of course, you still need to test it in the actual circuit. of.

The current consideration is the strength of the magnet, whether there is other magnetic field interference around the product, and whether shielding is required. It is recommended to use a standard magnet to understand the relationship between the distance change and the magnetic field intensity in the magnetic field gradient. The large distance change is reflected by the magnetic intensity difference. The magnitude of the magnetic intensity B is calculated from the output voltage value VH, and the minute distance change is known.

##### electronics，hall sensor
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