This is a two degree of freedom (DOF) head I was experimenting with. I used two cheap gearmotors from American science and surplus. It worked, but the hysteresis almost shook it to pieces. There were many problems with this design, including electrical, mechanical, and parts used. Electrically, it worked, but as already mentioned, there was a lot of hysteresis, or shaking when close to target. I made many efforts to reduce the effect, but with little success. I used the old bicore head approach, but I'm sure there are better alternatives out there. Mechanically, it worked, but with some difficulty. I relized early that the weight of the IC and power supply would drastically reduce the performance of the head, and so opted to tether the IRphotodiode eyes down through the base. This is OK because I never intended for the head to move 360deg. Even the tether was almost more than could be handled by the assembly, and the tether soon was doubling as a centering spring. Even the weight of the gear and motor led to some very inconsistent motion.

Parts were cheap, but there was trouble with their utilization. I had a very difficult time working out a transmission shaft. I finally decided to remove the outer cover, exposing a little red gear, to which I attached a transmission shaft. The removed cover was attached to the opposite side of the assembly to determine the axis of rotation around the transmission shaft. This worked OK, but not well enough to last.