These have been done and sitting for a couple weeks. Now I’m finally getting around to playing again. Wheel encoder board Two QRD1114 and a 74LS14 to square up the signal. Motor controller Built on a leftover protoboard from Gadget Gangster with an ATMega328 at 16MHz (yes, running as an Arduino) and a Pololu TB6612FNG motor driver. The two wheel encoders go to the interrupt pins....

Breadboarded wheel encoder. ATMega328 on the left, 74LS14 in the middle, QRD1114 on the right. QRD1114 on a radio shack proto board. So far it seems to work as expected. Guess it’s time to build the second one.