An article about a Hall sensor: what it is, what types of sensors exist. How to check the Hall sensor for performance. Where is it used and what for. How it works
What is a Hall Sensor?
Hall Sensor
- a magnetoelectric device, which got its name from the surname of the physicist Hall, who discovered the principle on the basis of which this sensor was subsequently created. Simply put, it is a magnetic field sensor. Now a distinction is made between analog and digital Hall sensors.
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Digital gauges determine the presence or absence of a field. That is, if the induction reaches a certain threshold - the sensor gives out the presence of the field in the form of a certain logical unit, if the threshold is not reached - the sensor gives out a logical zero. That is, with a weak induction and, accordingly, the sensitivity of the sensor, the presence of a field may not be detected. The disadvantage of such a sensor is the presence of a dead zone between the thresholds.
Digital Hall sensors are also divided into: bipolar and unipolar.
- Unipolar - triggered in the presence of a field of a certain polarity and turned off when the field induction decreases.
- Bipolar - react to a change in the polarity of the field, that is, one polarity turns on the sensor, the other turns it off.
- Analog Hall Sensors - convert the field induction into voltage, the value shown by the sensor depends on the polarity of the field and its strength. But again, you need to consider the distance at which the sensor is installed.
Where is the Hall sensor used?
Hall sensors have become part of many devices. Basically, of course, they are used for their intended purpose and measure the strength of the magnetic field. They are used in electric motors and even in innovations such as ion rocket engines. Most often, a Hall sensor is encountered when using a car ignition system. Such simple examples: proximity switches, liquid level meters, non-contact current measurement in conductors, motor control, reading magnetic codes, and, of course, Hall sensors could not help replacing reed switches, because their main advantage is their non-contact effect.
Hall sensor working principle
How does the Hall sensor work and where does this non-contact effect come from? Hall noticed that if a plate is placed in a magnetic field under tension, that is, with a current flowing through it, then the electrons in this plate will deflect perpendicular to the direction of the magnetic flux. The direction of this deflection depends on the polarity of the magnetic field. The phenomenon is called the Hall effect. Thus, the density of electrons on different sides of the plate will be different, which will create a potential difference. This difference is captured by the Hall sensors.
Below you can clearly see the process of operation of the Hall sensor, for example, a car ignition system unit is taken.
How to test the hall sensor for performance?
If you are faced with this problem in everyday life, most likely you are a motorist. Naturally, the easiest way, if the performance of the sensor is in doubt, is to replace it with a known good one. And if the replacement solved the problem, then the answer is obvious.
If you don't have a working sensor at hand, you can create a simple device that simulates its operation. To do this, you just need a piece of wire and a three-plug connector from the ignition distributor.
For diagnostics, you can also use an ordinary tester. If your sensor is faulty, then the tester reading will definitely be less than 0.4 V.
You can also check for a spark when the ignition is turned on. To do this, you will have to connect the ends of the wire to certain outputs of the switch.
If you are faced with a Hall sensor malfunction not in your car, but in another device, most likely you will need a tester, and everything will depend on the device in which the Hall sensor is applied.
