Greenwatts

CDS Tracker

This circuit can drive a single axis solar tracker and can be adapted to almost any size DC motor by simply matching the transistors to the motor. The circuit is very simple and all the parts can be recycled from scrap electronics or purchased for a few dollars. It is much easier to build than the sun switch circuit and can be powered by two 6 or 12 volt batteries.

The circuit consist of two CDS cells (photoresistors) a op amp voltage follower and comparator which biases a PNP/NPN transistor pair turning a DC motor either clockwise or counter clockwise.