I got up today thinking that I should grade final papers. Good thing I didn't. I spent my day putting together the cheapest persistence of vision I've seen (didn't see many examples though).
The POV circuit is on a perfboard with 8 LED and a 595 shift registor, a cheap light sensor from dipmicro (http://dipmicro.com/store/RPT-311PTA49
They don't even have a spec sheet. From what I found out by trial and error, it is sensitive to infrared as well as visible light. So I painted it black ;D
I used the cheap IR LED (http://dipmicro.com/store/SIR-311STA49
The perfboard is a buck a couple (http://dipmicro.com/store/PCB-UNI7H
I can safely say I spent less than $2 for this project. I was thinking about making a PCB but couldn't bare the long wait.
Here is the only picture I got so far. Camera ran out of battery and is on charge.
You may wonder what motor I used and why didn't I count that in my cost, well, I didn't use a motor. You will have to guess what I used. Hint: I started off the project and ended up sitting on a different chair ;D ;D ;D
Have to wait till tomorrow to charge up the camera and share setup pics.
Code is on my blog post:http://liudr.wordpress.com/2010/12/16/cheapest-persistence-of-vision-display-with-arduino-2/