The lightweight, but sturdy device is a real workhorse, ready to provide power in the field for contractors, third world homesteads, camping trips, vacation cabins, scientifc research field stations, recharging electric powered radio controlled model aircraft, and sound systems for park events.
The heart of the unit is a standard Intermatic wall timer (Model FD12HC), with a 21 tooth spur gear mounted on the 3/16" diameter timer knob shaft, and a 36 tooth spur gear mounted on the 1/4" threaded axis that holds and rotates the solar panel. The electrical contacts of the Intermatic timer were gutted to reduce drag. The massof the lightweight 12 Volt, 12 Watt mono-crystalline solar panel, delicately balanced, slows the speed of the clock mechanism about a third of one percent.
The spur gears were ordered from:
Sterling Instrument / Stock Drive Products
Excellent schematics provided online for all gears.
21 tooth gear:
Part Number: A 1T 2-Y24021
36 tooth gear:
Part Number: A 1T 2-Y24036