OP-AMP learning is a fun experience. By arranging different feedback components around an OP-AMP, a host of functional circuits are created. A few of these functions include,negative impedance, summing, difference, multiplication, logarithmic, simulated inductor, Low pass, Hi pass, Band pass and Band reject filters, Precision circuits,mixers, oscillators, precision rectifiers and all kinds of servo loop circuits and of course the analog computer that can handle all kinds of math manipulations including differential and integral calculus. The key to understanding and implementing these functions is the ability to recognize the type of feedback, be able to derive the necessary equations, solve for the desired function and validate the results. With practice you can start to develop your own circuits. The OP-AMP is only a high gain amplifier, nothing special, the secret is in the feedback circuit used. Want to be able to do this? Then you have come to the right place.