This ugly mess of a circuit sculpture is the final result of integrating all those functional components together:

This is the antithesis to Eirik Brandal, @MohitBhoite and Boldport. This is deliberate not just for lack of spare time, but also as a nod to my Dad who's own hacks always prioritised function over beauty.

I'm using a loose wooden frame to support the circuit vertically in the air. You can just about recognise each of the functional units documented in previous log entries. I've wrapped copper tape around the wooden supports to provide anchoring points to which the circuit is soldered, and to also provide the DC power of 5 to 6V.

I've added a PNP transistor and NPN transistor to connect the output of the Schmitt trigger to the control inputs of the H-bridge. Changes in light level cause the DC motor to change direction. Two diodes connect the bases of the H-bridge control transistors to the collector of one of the NPN transistors in the multivibrator. This implements a crude PWM that runs the DC motor at a slow speed. I also added an RC filter to the output of the light sensing unit to smooth out some of the erratic motion that would result from noise. Also had to add a 1000uF electrolytic capacitor across the supply voltage to help stabilise the voltage levels - running a DC motor with PWM tends to introduce big voltage swings. It's a wonder this works at all when using just a single power supply - typically we would want the motor driver on a separate supply from the control and sensing circuit. This could still be done in the future.

All the wires are solid core for extra rigidity. In keeping with the theme of recycled electronics, all the wire is either from discarded stock or from Dad's junk bin. The yellow and blue wires are discards I find near junction cabinets - BT engineers over here tend not to tidy up after fixing people's landline and broadband connections.