Hall Effect Sensor

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Hall effect sensors detect whether a magnet is near. Useful for non-contact/waterproof type switches, position sensors, rotary/shaft encoders.

Runs at 3.5V up to 24V. To use connect power to pin 1 (all the way to the left), ground to pin 2 (middle) and then a 10K pull up resistor from pin 3 to power. Then listen on pin 3, when the south pole of a magnet is near the front of the sensor, pin 3 will go down to 0V. Otherwise it will stay at whatever the pullup resistor is connected to. Nothing occurs if a magnet's north pole is nearby (unipolar).

Hall sensor.jpg


Example Project

The purpose of this project is to demo the usage of Hall Sensor. When the magnet is close to Hall sensor, the LED-L on Arduino will turn on, and the LED will turn off when the magnet is removed.

List of Components:

Item Quantity
Arduino Duemilanove or Uno 1
Hall Sensor 1
USB Cable with type A Interface 1
Mini Breadboard 1
Jumper Wire with Male Header 3
Resister with value 10K ohm 1
PC 1


Hall sensor sch.jpg


Hall sensor 1.jpg

Components needed for the project

Hall sensor 2.jpg

Wiring Picture

Hall sensor 3.jpg

When there is no magnet close to the Hall sensor, the LED-L will remain off.

Hall sensor 4.jpg

When magnet is close to the Hall sensor, the LED-L will turn off.

Pin 3 of hall sensor is connected to D12. D12 will detect the voltage level of D12 to judge if there is magnet close to it. The result will be displayed on LED-L which is controlled by D13.


<syntaxhighlight lang="c">

int ledPin = 13; int out = 12;

void setup() {

  pinMode(ledPin, OUTPUT); 
  pinMode(out, INPUT);    


void loop() {

   if ( digitalRead(out) )    


          digitalWrite(ledPin,LOW ); 





} }