Active filters are known as the best tools for harmonic mitigation as well as reactive power compensation, load balancing, voltage regulation, and voltage flicker regulation on the power lines. To introduce the operation of active filters in education, it is a good method to use a software, named SPICE. It is a good choice, because it has a high level of objects for simulation, and good presentation objects for visualizing the results. Students can easily change the parameters of the operation, and can see the its result instead of using real power electronics circuits. In this paper we would like to use a series active filter as the power factor corrector for a "capacitive input" circuit. ©2010 IEEE.