Difference between revisions of "Hall Effect Sensor"

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[[Category:Sensors]]
===Overview===


[[image:hall effect sensor.jpg|right|200px]]
A Hall effect sensor is a transducer that varies its output voltage in response to changes in magnetic field density. Hall sensors are used for proximity switching, positioning, speed detection and current sensing applications. In its simplest form, the sensor operates as an analog transducer, directly returning a voltage. With a known magnetic field, its distance from the Hall plate can be determined. Using groups of sensors, the relative position of the magnet can be deduced.
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Basically, by placing a hall effect sensor near a magnet attached to your device that moves in some way, you can get a voltage proportional to the distance/orientation of the magnet. One commonly used configuration is placing the sensor directly above a dipole magnet attached to a rotating joint or shaft. The sensor (with some circuitry) will return an analog voltage proportional to the angle of the joint or shaft.
A Hall effect sensor varies its output in response to a change in magnetic field. They are primarily used for proximity sensing and position/rotation sensing. By placing a hall effect sensor near a magnet attached to your device that moves in some way, you can get a voltage proportional to the distance/orientation of the magnet. One commonly used configuration is placing the sensor directly above a dipole magnet attached to a rotating joint or shaft. The sensor (with some circuitry) will return an analog voltage proportional to the angle of the joint or shaft.


===How It Works===
==How It Works==


As you can tell from the name, the Hall Effect Sensor takes advantage of the phenomenon known as the ''Hall Effect''. The Hall Effect refers to the potential difference (Hall voltage) on opposite sides of a thin sheet of conducting or semiconducting material in the form of a 'Hall bar' (or a van der Pauw element) through which an electric current is flowing, created by a magnetic field applied perpendicular to the Hall element. The equation associated with this is
As you can tell from the name, the Hall Effect Sensor takes advantage of the phenomenon known as the ''Hall Effect''. The Hall Effect refers to the potential difference (Hall voltage) on opposite sides of a thin sheet of conducting or semiconducting material through which an electric current is flowing, created by a magnetic field applied perpendicular to the Hall element. The equation associated with this is


<math>V = I \times B</math>
<math>V = I \times B</math>
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===Circuitry===
===Circuitry===


Hall sensors come in small IC packages and usually have three pins. The inside is simplified in the diagram below:
Honeywell makes a small hall effect sensor that can be mounted on a PCB board called the SS49. This device is used for analog sensing (angle, distance, etc.) A diagram of the circuit is shown below.


[[image:hallsensorcircuit.jpg|400px|center]]
[[image:hallsensorcircuit.jpg|400px|center]]


==Applications==
A company called iC-Haus makes another hall sensor chip that is intended for makeing angular measurements. The setup is shown in the diagram below:


===A Switch===
[[image:hallsensorsetup.jpg|400px|center]]


The following circuit shows how a hall effect sensor can be used as a switch. The LED will light up when the sensor detects a change in the magnetic field.
===Connecting to the PC/104 Stack===

[[image:hall effect switch.jpg|center|300px]]

===Detecting a Nearby Ferrous Object===
You can use a hall-effect sensor to detect a nearby metal object. An example of how to assembly such a sensor is shown below:

[[image:ferrous sensor.jpg|center|300px]]

A small magnet is placed next to the hall effect sensor. Normally, the magnetic fields are uniform, but as a metal object approaches, they are changed. The hall sensor picks up on this change and outputs a voltage.

[[image:ferrous sensor operation.jpg|center|500px]]

===Angle Sensing===

By mounting a bipolar magnet on a shaft and placing a hall sensor near it, you can use the hall sensor to measure the angle of rotation of the shaft. The setup below was used in the "haptic paddle" project. The small magnet is attached to the shaft and the small hall sensor is just below it.

[[image:hallsensorsetup.jpg|center|400px]]




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*Wikipedia, "Hall Effect Sensor", http://en.wikipedia.org/wiki/Hall_effect_sensor
*Wikipedia, "Hall Effect Sensor", http://en.wikipedia.org/wiki/Hall_effect_sensor
*Honeywell, "Hall Effect Sensors", http://www.honeywell-sensor.com.cn/prodinfo/magnetic_position/technical/chapter2.pdf
*Honeywell, "Hall Effect Sensors", http://www.honeywell-sensor.com.cn/prodinfo/magnetic_position/technical/chapter2.pdf
*Quasdorf, Joachim, "A Case Study: MR vs. Hall Effect for Position Sensing," http://www.sensorsmag.com/sensors/article/articleDetail.jsp?id=314520, Nov., 2005.
*iC-Haus, "iC-MA", http://www.ichaus.com/upload/pdf/Ma_a2es.pdf

Latest revision as of 10:29, 17 February 2008


Hall effect sensor.jpg

A Hall effect sensor varies its output in response to a change in magnetic field. They are primarily used for proximity sensing and position/rotation sensing. By placing a hall effect sensor near a magnet attached to your device that moves in some way, you can get a voltage proportional to the distance/orientation of the magnet. One commonly used configuration is placing the sensor directly above a dipole magnet attached to a rotating joint or shaft. The sensor (with some circuitry) will return an analog voltage proportional to the angle of the joint or shaft.

How It Works

As you can tell from the name, the Hall Effect Sensor takes advantage of the phenomenon known as the Hall Effect. The Hall Effect refers to the potential difference (Hall voltage) on opposite sides of a thin sheet of conducting or semiconducting material through which an electric current is flowing, created by a magnetic field applied perpendicular to the Hall element. The equation associated with this is

Circuitry

Hall sensors come in small IC packages and usually have three pins. The inside is simplified in the diagram below:

Hallsensorcircuit.jpg

Applications

A Switch

The following circuit shows how a hall effect sensor can be used as a switch. The LED will light up when the sensor detects a change in the magnetic field.

Hall effect switch.jpg

Detecting a Nearby Ferrous Object

You can use a hall-effect sensor to detect a nearby metal object. An example of how to assembly such a sensor is shown below:

Ferrous sensor.jpg

A small magnet is placed next to the hall effect sensor. Normally, the magnetic fields are uniform, but as a metal object approaches, they are changed. The hall sensor picks up on this change and outputs a voltage.

Ferrous sensor operation.jpg

Angle Sensing

By mounting a bipolar magnet on a shaft and placing a hall sensor near it, you can use the hall sensor to measure the angle of rotation of the shaft. The setup below was used in the "haptic paddle" project. The small magnet is attached to the shaft and the small hall sensor is just below it.

Hallsensorsetup.jpg


References