Robo Jr. Light is a basic light follower. It follows a light source such as a flashlight. It has two photo sensors, one on the front right corner and another on the front left corner. It is powered by two motors. Robo Jr. Light has two CdS(Cadmium Sulfide) photo sensors. Light is received by these sensors where it is converted into an electronic signal. This signal travels to a logic IC (Integrated Circuit.) The logic IC generates control signals for the two motors. When both sensors detect light, the robot goes straight. When the left or right sensors detect light, the robot turns towards the source and continues on. This is a kit and requires assembly. The circuit board is pre-soldered. Size: 130 x 87 x 47(H) mm. Requires Four (4) AA Batteries (not included.) 1 Each Robo Jr. Light RASMR3$74.99 Copyright © 2003-2008 E-Clec-Tech. All rights reserved. All other materials and logos are copyrighted by their respective owners, or companies.