2DOF Beam Solar Tracker

This 2 degree of freedom solar tracker is powered completely by the sun - no batteries here! A 6v 200mah solar cell charges a 10,000uF capacitor, and a driving circuit drives two gearmotors accordingly. Four infrared phototransistors serve as sensors. The frame was laser cut from hardboard. More info to come!


For my first journey into BEAM robotics I thought I would make a solar tracker. I decided to use Wilf Ritger's schematic shown below.

Motors are probably one of the most important parts of a robot like this. Ungeared motors don't have enough torque to work reliably, so I chose some gearmotors from BG micro.

Next I designed a model of the robot in Solidworks. The hardest part of any kind of motored robot is the mounting of the motor shaft. My paticular motor had a 2mm shaft, so I came up with the idea of using a RC airplane propellor saver to screw on to the shaft, and having the robot parts attached through the screws. It worked great!

Dead bug construction of the circuit:

First prototype. Frame is laser cut from hardboard. The solar panel is rated for 5v 100ma, however it didn't have enough juice to move it like I wanted. Later I ordered and used a 6v 200ma panel which worked just great.

Here is a PCB of the circuit, not yet tested.