Now that I have the multitracker operational, I decided that it would be fun to use the new servo board in a different way to demonstrate how the same board that tracks the sun can also operate an X-Y servo stage. The servo amp when used in this way, requires a position command voltage,and position feedback voltage.

I dug through my extensive stuff pile, and found some chart recorder mechanisms that I had purchased at the MIT swap meet several years ago. The assemblies have a cable drive system that moves the pen holder, with a 1K linear position feedback pot. I was going to move a stage with a block of wood so the direct drive motors would not have enough torque to do the job, so I mounted gear motors to the assembly to generate sufficient torque to lift the stage.I mounted two pieces of G10 copper clad circuit board material to both pen holders as the actuator arms. A phenolic block with a notch in the rear for the two control arms became the moving stage that the block would be mounted to.

The command pot in my device is a joystick, but any pot will work.

The position feedback pot needs to raise its output voltage when the command voltage raises or the servo will shoot off to one end or the other, and stall the motor. Not a good thing, so make sure that the stage moves the right way and stops when it gets in sync with the joystick if it does not sync, reverse the motor leads so it goes the other way, and you should be good to go.