Original report by John Schimmel

So basically I was wondering why every sensor dealer was selling the hall effect sensor. So I did some research and found some projects in the Forrest Mimms books, as well as their great animation at Melexis.

The datasheet I used was from Jameco's item - it's simple and limited. http://jameco.com/wcsstore/Jameco/Products/ProdDS/174043.PDF

Latched Hall Effect Sensor

Using a magnet attached to the back of the sensor, the hall effect detects the magnetic field perpendicular to the supply voltage. There are different types of hall effect sensors, this one is latched and acts more as a switch than a sensor. There are linear ones that behave and can relay more information about motor gear heads, direction of movement and speed.

The Datasheet


  • 3 - 20 Volts - easy to understand
  • 3 pins - datasheet provides pin identification
    • pin1 - Vcc
    • pin2 - Ground
    • pin3 - output

Absolute Maximum Ratings - this is the section to read before you hook it up.

  • Supply voltage < 20v
  • Supply Current < 8mA
  • Environmental temperature anywhere from -20 -- +85 C

Typical Characteristics Curves:

  • The one interesting curve displays the hysteresis deviation affect against temperature. At freezing conditions 0 C the hyteresis is 0. As the temperature increase the hysteresis increases, as the temp. decreases the hysteresis decreases.
  • hysteresis is - "Non-uniqueness in the relationship between two variables as a parameter increases or decreases. Also called deadband, or that portion of a systemís response where a change in input does not produce a change in output." here