Prototype diesel-electric locomotives use a diesel engine driving an electric generator to power DC (or more recently AC) motors wrapped around a single axle of a wheelset. The equivalent is not usually found in HO scale… until now. There is a story behind this, with a path leading in unanticipated directions. A “working” HO single axle traction motor can be built. This bit of experimental modeling starts here, but this is likely not the end of the story.

I mentioned in another threadf that you can build a touch-control panel, using capacitive touch, very cheaply.

 What I have in mind is a small panel, 4 x 6 inches or so, with pennies and a single wire to  each functioning as capacvitive touch sensors, servos operating the turnouts (and, a factory gate, in my case) all working through an Arduino. I'm be using an Arduino Uno because it's what I have on hand, but you could use a Nano  as well.

I'm considering buying a Bachmann GE 44-ton and/or 70-ton HO loco. The ones I have my eye on are non-DCC, because I plan to build my own radio-controlled dead-rail system. What I'm trying to determine in advance is how much space I can expect to find inside. I have one larger Bachmann loco (GP38? Not sure) which has a single powered 4-wheel truck, and unpowered 4-wheel truck, and lots of empty space inside.