[Pinomelean] has posted an Instructable on how to create a mini line following robot using only analog circuitry ... and this is one of them. The circuit consists of two op-amps that amplify ...

The creation of [Ondřej Staněk], this matchbox-sized line following robot is quite impressive. PocketBot’s 48mm x 32mm circuit board ... are driven independently using a set of mobile phone ...