This line tracking robot car was built base on the prototype mentioned in the previous knowledge item. You can find the details for the prototype: http://www.rs-online.com/designspark/electronics/eng/knowledge-item/arduino-line-tracking-robot-car-prototype Bills of Materials: PCB   Geared Motor OSRAM Opto Semiconductors Photodiode (RS stock number: 654-8902) Nichia LED (RS stock number: 713-3996) RS 10 ...