With Photodiode
http://www.thebox.myzen.co.uk/Workshop/LED_Sensing.html http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1228993480 http://www.arduino.cc/playground/Learning/LEDSensor http://fritzing.org/projects/h-bridge-2-dcs-motors/
the note and web link about education for sharing knowledge