Persistence of Vision Clock
The Persistence of Vision (POV) Clock works on the principle that the human eye can only "refresh" itself at a fairly slow rate. By taking advantage of this phenomenon, one can "paint the retina" of the eye for a limited duration. (Think of glancing at the sun for a second, and how its circular silhouette appears wherever one looks afterwards... of course at a much less blinding level!) The POV Clock essentially waves a rod with light emitting diodes (LED) on its end that flash in carefully constructed combinations to "paint" the time. The rod moves fast enough such that the time appears to be floating in "thin air". This project was singled out of 200 designs as the most creative project of the year and is showcased to potential Electrical Engineering students each summer. Here is an image of it in our lab (click to enlarge):![[POV Clock]](http://proditus.com/images/POV_Clock.jpg "Persistence of Vision Clock")
We were also lucky to have a non-SLR digital camera around us, so we captured a couple of seconds of it working in real-time. The frame-rate of the video sadly does not coincide perfectly with the refresh rate of the POV Clock, but it is enough to show it working. You can watch it here.
An Excerpt of Technical Details
Number of team members: 2 (including myself)Amount of time spent: ~13 hours
Processor: Motorola 68306UM
Language of development: 68K assembly
Lines of code written: 357
Equipment list (partial):
- 1 Lego kit (2 motors, 1 photo-voltaic sensor, 1 custom controller, and random pieces)
- 8 LEDs on a foam/sponge rod
- 1 breadboard with custom LED driving circuitry
- 1 development board (UltraGizmo Board) controlled via a PC terminal
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