Hall Effect Sensor
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
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.
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:
Connecting to the PC/104 Stack
- Wikipedia, "Hall Effect", http://en.wikipedia.org/wiki/Hall_effect
- 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
- iC-Haus, "iC-MA", http://www.ichaus.com/upload/pdf/Ma_a2es.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.