Both my LCPE and LC+ NW2 provided 5VDC to the resistor (and fan). on the polar express, if I recall correctly the optical sensor provides a low pulse, and this could be tapped directly into a microprocessor without causing any problems. at least it worked fine when I was messing around to see if I could make it do 4 chuffs per revolution. ( that didn't end up working out very well, sounded like crap and the sounds couldn't keep up) if needed you can also tap into the connector for the opto to get a constant 5vdc source to run a uP.
As for the smoke running or not, I think it depends on the engine. on the NW2, it runs the fan slowly and turns down the smoke but still smokes at idle. I'm unsure if the lc+ steamers do that or not.
side note, after not using the smoke for the last 3 years or so, it looks like I need at least a new motor. it's squealing like crazy.
