Pinomelean wrote this instructable detailing the build of his analog line tracer robot driven by a dual op-amp chip:
It’s a simple line tracer, controlled by two op-amps. No microcontroller, no programming… simple analog circuitry.
I tried to make it as small as possible, using SMD components and tiny motors.
I’m very happy with the final result, the robot can follow 1-2cm wide black lines on white background, and is quite fast.
It can be made to follow white lines on black background by switching the position of a couple components.
Check out the video after the break.