Why do O-Gauge trains use AC power to the track?
The short answer is thats the way it has always been. Electric trains pick up power for the motors and lights from the track of course. Electricity needs two connections in order to flow. In simple terms hot and ground leads for Alternating Current or positive and negative leads for Direct Current. In the early days of all metal electric trains, rather than try to build a model in which the wheels had to be insulated from each other and from the metal frame, it was MUCH easier to manufacture a model where all the wheels picked up one lead of power from both of the outside rails. An insulated center rail was added to provide the other lead to a simple insulated pickup attached to the underside of the train. With advances in manufacturing technology there have been many 2-Rail variations over the years (and most other sizes of trains have adapted the 2-Rail format) but the traditional 3-Rail style has endured in O-Gauge railroading. As far as why the difference between AC and DC power at
