Quadrature encoders

[Max Lobovsky]

As a rookie team this year, we didn't have time to do much more than the basics with out control and programming system, but i have been reading about the hundreds of ways to improve them. I understand a quadrature encoder has two different striped rings so that two sensors can be used to tell which direction the thing is spinning.

What systems have you used that work effectively?
If you bought it, how did you adopt it to work for FIRST?
If you built it, how?