The Stalker Headbot is a light seeking robot, unlike the photovores the Headbot is a stationary robot which turns on the spot to the brightest point (or if preffered turns away from it). The Headbot has the ability to be mounted onto another robot, the application of this could be to find the optimum point to charge a robot as it moves. This is known as horse and rider style.
I originally built this using a servo, however it was far too power hungry, and despite adding two solar cells in paralell and adding more caps, it just couldn't turn. The next
thing I tried was to add a buffer chip to help buffer the signal and drive the motor, no luck!
I then used a geared motor, and seem to be having more luck with this, I am still not sure that it is working as well as I would like, but for now it is not a priority robot to continue on.
26/02/06 - Update
I have now upgraded Stalker (above) and she works better than ever before! Stalker now runs without a buffer chip, and is able to run from just one solar cell.
The major upgrade is to change the motor for a low starting current solar motor... not only that but it has a gearbox too. I bought the solar motor with gearbox from eBeamUK, however I have now found the same motors cheaper from RapidElectronics, at only £2.50 including the motor!!! I have also upgraded the capacitor bank, and changed the legs. Stalker now runs from three 4700uF caps.