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The Essential Guide to Hall Effect Sensor Circuit – Working

The genius brain behind the Hall effect sensors is Edwin Hall. People loved his invention so much that they called these sensors after his name. Hall discovered that there is no harm if magnetism and electricity perform together to instill motion in machines and electronics.

These sensors transform the magnetic data into electrical signals for transmission. Not just this, Hall effect sensors have highly significant applications in different fields. Especially the automotive industry greatly depends on these sensors to detect motion, speed, and distance through the machines.

The ABS also relies on Hall effect sensors, and combustion engines can surely never perform efficiently without these sensors since these are important for regulating the timings. We are going to discover different aspects of Hall effect sensors for you through this post.

So if you had any confusion regarding this remarkable invention of physics, this post would clear out the air for you this instant! Let’s get started! 

Working of Hall Effect Sensor Circuit 

hall effect sensor circuit
hall effect sensor circuit

The Hall effect sensors follow a systematic series of steps to function. We are going to decipher their function through the following steps for better understanding:

  • The process starts when the current interacts with a material.
  • The current carries electrons and moves along the magnetic field in a straight line which means the magnetic field does not deflect them as of now.
  • Now, if you develop an electric field between two magnet poles, it will cause the electrons to deviate and move along a curved path when they pass through the same material.
  • This deviation happens because two magnetic fields are colliding with each other making the electrons follow a new path. 
  • After this, there will be a large number of electrons present in one area of the material. 
  • Due to this, the voltage will take place, making a 90-degree angle to the magnetic field. 

Wait, did we not talk about the working of Hall effect sensors? So these sensors have a semiconductor made of silicon. The sensors perform to determine the changes in the voltage when you will play with an object by putting it in a strong magnetic field. The priority of this sensor is to first detect the magnetic field and then check the position of the object that you have placed before in the magnetic field. 

Hall Effect Sensor Circuit and magnets

Magnets are crucial for the Hall effect sensors to perform accurately. Otherwise, they will fail to give you desired results. Now these magnets need activation so that they can pair up with these sensors to work.

An external magnetic field can influence the magnets for activation. It will allow the sensor to detect the distance of an object and see if it’s near to the sensor or far from it. We are going to support this concept with an example so that you can relate to it better.

Example: Suppose you have placed a sensor in the frame of a door. Now you have also positioned a magnet on the door that we are going to play with in this experiment. Since there is a magnetic field created by the magnet, the sensor will be able to detect the closing and opening of the door with the help of this magnetic field. Now, every magnetic field has two incredible features. The first one is flux density, and the second is polarity. 

Flux Density: It helps you determine how much magnetic flow is passing as per unit area 

Polarity: These are the poles of a magnetic meaning the North and South Poles

What is Hall Effect Sensor Circuit or Voltage?

The Hall Effect sensors have their own output signals, which are basically the magnetic field that surrounds an object. These have a definite threshold as well. Now if the flux density increases this threshold, the sensors will start detecting the magnetic field with the help of an output which we call Hall voltage. 

Important parts of working of Hall Effect Sensor Circuit 

  • There is a small and slim chunk of a semiconductor in these sensors, and its job is to let the current flow through its body without any interruption to produce a strong magnetic field.
  • When you bring an object near to a magnet, the magnetic flux will put some pressure on this semiconductor as well.
  • Due to this pressure, the electrons will start moving, and while they move, they also produce Hall voltage which ultimately triggers the sensor.
  • This Hall voltage is in direct relation to the magnetic field’s strength. 
  • Normally, you will find that Hall voltage is always some microvolts that are useful for logic switches, DC amplifiers, and regulators. 

Types of Hall Effect Sensor Circuit 

We can classify Hall Effect sensors into two categories. 

  • Linear/Analogue output devices
  • Digital output devices
  • Linear/Analogue Output Devices: These sensors keep producing a voltage that increases as the magnetic field gets stronger and will reduce in a weak magnetic field. It always works on the strength of the magnetic field, which will boost if you will bring an object close to the magnet. It will also boost the output signals unless it approaches the limit of the power supply in the system. 
  • Digital Output Devices: These sensors have a special Schmitt trigger which is a certain type of circuit that gradually changes the output as per the voltage fluctuations depending on the threshold levels. Now this is how the Schmitt trigger works its magic for the digital output sensors. If the magnetic flux crosses the limit of the threshold value, it will turn the switch ON. 

Types of Digital Hall Effect Sensor Circuit 

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Well, did you know that you can classify Hall effect sensors based on the type of magnetic field generated? Yes, it’s completely true, and due to this, we get unipolar and bipolar sensors that have their own magnetic fields for functioning. 

  • Bipolar Digital Hall Sensors: A positive and strong magnetic field is important for these sensors to perform. Now how do you know which pole of the magnet has the strongest magnetic field? It is the South Pole! The negative field of the North Pole is also equally important for bipolar systems. 
  • Unipolar Digital Hall Effect Sensors: These do not need both magnetic fields. Unipolar sensors can work on a single magnetic field that is positive and comes from the South Pole. 

Demrit of Digital Hall effect sensors:

  • One issue with these sensors is that they have extremely less output drive, which is why many electronics that involve such sensors cannot tolerate heavy loads at all. 

How does Digital Hall Effect Sensor Circuit manage heavy loads?

Since these sensors have to be ready to tolerate heavy loads, there is one thing that can make it happen for these sensors. It is an open-collector NPN transistor that makes them efficient in enduring heavy loads smoothly. Here, the role of a transistor is to act as a switch. It keeps the output short and keeps it closer to the area where there is more magnetic flux. 

Different Types Depend on Magnetic Positions and Movements of Hall Effect Sensor Circuit 

So if you consider the position of the magnet and how it moves and goes away from the sensor, you will have different types of magnet movements. These include:

  • Sideways
  • Head-on
  • Push-push
  • Push-pull

We are going to elaborate on two typical types of magnet movements other than the abovementioned movements:

Head-on detection of Hall Effect Sensor Circuit 

  • In head-on detection, the magnetic field should be perpendicular to the sensor.
  • While the magnetic will remain in a straight direction to come closer to the sensor.
  • When you are using linear detectors, remember that they will determine the magnetic field’s strength with the help of the magnet’s distance.
  • When the magnetic field is strong, it means the distance is less, which will increase the voltage. 

Sideways detection of Hall Effect Sensor Circuit 

  • The magnet takes a sideway approach in this case and goes through the sensor.
  • Such detection comes in handy when you need to work with rotational magnets.
  • Also, it is reliable for determining the speed of the motor working in a rotatory motion. 

 

 

 

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