Buy this sensor or or kit.

KEYES ARDUINO photo interrupter module

Photo interupter module use the buildin arduino led. If the sensor is broken the LED is turned on.

Device senses a signal, LED lights, otherwise off.

Schematic

If you view from the top like on the photo

• Left = Ground
• Middle = +5V
• Right = Signal

Connect the module to the arduino as follows:

• Arduino pin GND to module GND
• Arduino digital pin 3 to module Signal
• Arduino pin 5V to module 5V

Example Code

// Example code for KY-010
// photo interrupter module
 
int Led = 13 ;// define LED Interface
int buttonpin = 3; // define the photo interrupter sensor interface
int val ;// define numeric variables val
void setup ()
{
  pinMode (Led, OUTPUT) ;// define LED as output interface
  pinMode (buttonpin, INPUT) ;// define the photo interrupter sensor output interface   
}
void loop ()
{
  val = digitalRead (buttonpin) ;// digital interface will be assigned a value of 3 to read val
  if (val == HIGH) // When the light sensor detects a signal is interrupted, LED flashes
  {
    digitalWrite (Led, HIGH);
  }
  else
  {
    digitalWrite (Led, LOW);
  }
}