In this case I think the most simple thing is to use an electrical motor to drive some dedicated 400Hz generator.

 

Specifically, the frequency changer needed (Input: ~115V AC, 60 Hz, single phase; Output: 115V AC, 400 Hz., single phase) will be used to power a small 115V AC, single phase, 400 Hertz motor, drawing approximately 0.8 amperes under load. I would like to keep the frequency changer simple, small, and lightweight -- something inexpensive to build if possible. I am considering all ideas previously posted, and I'm hoping to find a schematic or an inexpensive product (~$100) to make this project a success. Please see attached schematic symbols for the fwd/rev motor circuit. Again, I greatly appreciate all help!