Cable wound up on cable spool attached to screwdriver

Rear view of screwdriver attached to railing mount plate

Initial test set up, with screwdriver lashed onto railing (note use of polypropelene twine for testing).

Detail of screwdriver lashed to railing for test

View from railing during test of screwdriver cable positioning

The motor pulls a cable through a pulley to change the angle of the solar cells in one direction as it takes cable up. The counterweight provides motion in the other direction when the motor turns in reverse and pays cable out. This is a simple, but effective solution that adds only a few watts per day to our overall energy budget.

Controller card for the battery-powered screwdriver motor

To enable remote computer control over our battery powered screwdriver we used an 8-channel controller card that could connect up through the parallel port to our PC. The desirable angles and timings are pre-programmed and run every day as a background application. At night, when the solar cells generate no power, the cells are set into the starting position for the next day.

The controller at work

Soldering leads to the controller