Thanks muchos.
i have a large cap across the rails, and a small one too, [.1uF]. i teach basic electronics and PIC programming at Parsons, and have been over and over the importance of placing capacitors as filters. now i guess it's time i did some learnin' too!
so, it looks like i'll be putting together some more sophisticated filters.
i don't own a scope, or anything really useful like that, so i'm not sure how well i can track down the actual noise in the circuit....

the project i'm working with now is a prototype of a much larger installation.
i will post a link to the latest images and video tonight.

again, thanks for the help, i'm going to read Ken's noise reduction notes on the train today.

back soon with pics,
joel