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.

Starseeker

I returned to the Bicore chip to build a light seeking head, and I chose to use Wilf Rigter's Solar Powered Smart Head Revision 3 schematic. Pretty standard design with this one. I used some solid 8AWG copper wire for the frame. I originally tried to solder the heavy gauge wire together, but I couldn't get the wire to heat up enough. So i used krazy glue yet again.

My aesthetics on this one were pretty poor, but I was more concerned with building an appropriate frame to mount the bot on. The motor is an Omron R2DG-B01-30. My smallest gear motor I had. I believe it was salvaged from a DVD drive. The storage capacitors are three 0.3F supercaps wired in series to boost the operating voltage to a max of 8.1V, which this solar panel is capable of putting out!

Unfortunately this bot doesn't perform as well as I'd hope. It seems to have trouble with the 1381 latching, similar to Simon Fraser, who used the same schematic. It will stall in bright light, not function at all in lower level light, and only seems to turn sporadically. At least it turns in the right direction. If anyone has any advice, I could use it here. I never seem to have much luck with wilf's circuits.

EDIT: So after some testing in actual sunlight, it seems to perform much, much better. Even though the solar panel is putting out more than enough voltage for the 1381 to latch, it doesn't seem to cooperate in lamp-light. I'm sure more research is needed into the circuit theory as to why this is.

Syko

Syko is a Bicore based light tracking head based on Wilf Rigter's Solar Powered Smart Head circuit V1. Sadly, I could never get him to function properly. He was relegated to the parts bin and scrapped for a separate project years later. His motor is a Copal 60 RPM gear motor. Connected to the shaft you will see a motor clamp repurposed from a screw terminal block. They are 3mm in diameter, made of brass, and have two screws to keep the motor shafts secure and in place. Connecting things to motor shafts is tricky, and these little clamps are a godsend. I haven't used the ones from Solarbotics, but the ones I purchaed on amazon here worked just fine for me.

ITP Fab - Motor Mounts from Jeff Feddersen on Vimeo.