This version of the QRE1113 breakout board features a digital output, using a capacitor discharge circuit to measure the amount of reflection. This tiny board is perfect for line sensing when only digital I/O is available, and can be used in both 3.3V and 5V systems. Project description, more information and ordering can be found at https://www.sparkfun.com/products/9454 Datasheet: http://www.sparkfun.com/datasheets/Robotics/QR_QRE1113.GR.pdf Bildr Tutorial: http://bildr.org/2011/06/qre1113-arduino/