This is a couple of years old, but I never posted it. So, for posterity, here is my attempt at a 'persistence-of-vision' display. Only 5 LEDs on a spinning arm, and definitely a junkyard build, but effective. I used a micro-switch that was bumped every revolution as my '0 degree' indication, which made a lot of noise and reduced the revolutions a bit. It would have been better if I had used a 'hall-effect' sensor (but I didn't have one) or even an infrared emitter/detector. Next revision?