http://www.utopiamechanicus.com/article ... d-optical/
光電關關 Photo Interrupter
Re: 光電關關 Photo Interrupter
http://www.arduino.cc/en/Tutorial/Button
That same leg of the button connects through a pull-down resistor (here 10 KOhms) to ground
That same leg of the button connects through a pull-down resistor (here 10 KOhms) to ground