Starchaser

Starchaser is a power-smart head with two degrees of freedom. This means it can rotate horizontally and vertically to orient itself towards the brightest source of light in order to maximize its power gathering. I went with the Power-Smart Head circuit again, and this time I ramped up the solar power, using the same panel from the Mazibug, 5V @ 200mA. This panel will easily provide more than enough power in full sunlight. It is a bit large, and definitely commands the focus of the design.

I chose my standard N20 micro gear motors; the 30 RPM variant. I wanted to have precise enough control that the bot wouldn't over-rotate when attempting to focus on a light source. The base is built with brass nails from a wall-hanging kit, that fit perfectly into these screw terminal blocks that I use quite often. They are a perfect match with the N20 gear motor shaft. The bracket that the solar cell attaches to is from the wall hanging kit as well.

Hidden underneath the heat shrink tubing is the Photodiode sensor array. I used break-away female headers to make the testing phase easier, but I liked the function of the setup and decided to keep it in the final design. The heat shrink tubing narrows the photodiode's field of vision from a broad 150 degrees to something more focused.

I used more header pins on the resistors coming from the photodiode array, that way I could swap in different resistor values to adjust the bot's sensitivity to light on either axis. I would have liked to use trimpots for this, but I didn't have any in the 1-5meg range.

Overall I am super pleased with this circuit and its performance! It has constant action and perfect accuracy in the sunlight, and doesnt perform too bad under lamp-light either! Eventually I will build one of these on top of a larger robot as a power source, and/or as a steering function.