Sallen-Key Low-pass Filter Design Tool

Here is a tool, excelent toool to help us to design active filters.

Sallen-Key Low-pass Filter Design Tool:

http://sim.okawa-denshi.jp/en/OPstool.php

Some theory can be found here:

http://quidel.inele.ufro.cl/~jhuircan/PDF_CTOSII/ieeefact.pdf

that's all.