In this project I turned my fan into a POV display(Persistance of vision). The way it works is there is a single strip of LEDs on one of the blade. There is an optical sensor on the back which resets the image every time the fanmakes one revolution. The program then holds each column of pixels a small amount of time, then moves on the next column. The total time that all the columns are held must add up to be less than the time of one revolution.
2.0 Power and Programming
I made an earlier version of this fan with only one color and using using batteries as the main power source. The main problem I found was that the batteries tended to run out fast and replacing them would constantly throw the balance off of the fan so you'd have lots of shaking. In this earlier version I also had to remove the entire main board to program the microcontroller, which also introduced balancing problems when it was it was re-programmed.
This time I powered it using a wireless cellphone charging kit I found on ebay for under 10 bucks. Using this I only have to balance the fan once and dont have any batteries to replace. I've also included a jack on the side to connect the pickit 3 programmer to upload a new image.
more info to come...