But I sure hope you are not trying to rectify the AC output directly from the wall socket! That would fry your motors. I assume you have a transformer that is putting out AC at about the same voltage that the DC motor operates at. How are you planning to control the speed?
Bridge rectifiers cannot change DC to AC. They will only change ac to dc.
I am not understanding your question; Lionel Trains normally use reversible universal motors and are run on AC.
