Thanks to 3D printing and easy access to electronics parts, adding motion to signs is easy. This is my classroom’s sign. I adopted T-slot aluminum extrusions for the sign’s frame so that I could easily attach sub-signs, flyer holders and so on. That made it easy to attach my motorized gear train to the top. The small gear on the upper left is driven by a geared DC motor on the back. The gear ratio os each engagement is 1:2, so the speed of the gear in the upper right is 1/16 that of the input gear. Speed is controlled with the green knob on the left, which adjusts the output voltage of an LM317 regulator.
