Thanks for the reply, Alan! Arduino sounds intriguing. The basic idea is one or two light circuits per building, maybe inside and outside. I was thinking of a controller per building which if using a Light-it decoder means an extra $5 per building. I like the size. But could an arduino controller be, say, an inch square or less? If so, I would probably enjoy tinkering with the circuits. Just don't know anything about it yet. And can arduino be controlled by JMRI? Or does that require a different interface? Like I said, I don't know anything about it yet.
A couple of other questions... If I use RailPro for loco control, that means there is a constant voltage on the rails. Can the arduino control instructions be multiplexed onto that DC voltage? OR would it make the RailPro LM3S go nuts? The reason I ask, is that I had mentioned reed switches for control of lighting in rolling stock. Do you think arduino could be used for that, too, instead of reed switches and magnets?
And, regarding the first questions, can you direct me to an article or articles that could explain how to go about building arduino circuits for either of these applications? Thanks.