You might find this video that I put together helpful. It describes a purely practical way to understand how most op amp circuits operate by considering some basic properties of op amp operation, without relying on a bunch of formulas. Maybe it will help with your understanding:
http://www.youtube.com/watch?v=K03Rom3Cs28
Alan
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http://www.youtube.com/w2aew
http://www.youtube.com/watch?v=K03Rom3Cs28
Alan
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http://www.youtube.com/w2aew