To control the speed and direction of the turntable, I decided to use a mobile DCC decoder. I will be using a Digitrax DZ-121. I chose that decoder because I had one available from a locomotive that is no longer an active running model. The first thing to do was to install the DCC system on the layout into which this turntable will be installed. I then connected the rails in the turntable pit to the track power bus of the layout. The locomotive's headlight is on! I was able to move the locomotive up and down the bridge track.
The schematic for the connections is shown below. The decoder's supply wires (red and black) are connected to the DCC bus under the layout. The orange and gray wires from the decoder are connected to the turntable motor. I may hook up the light output function wires of the decoder to some lights on the turntable (for night-time operations). The rails in the turntable pit will be controlled via a Digitrax PM4, which allows for automatic polarity reversal on the rails as the bridge is turned.
This is the view of all the wires from the decoder hooked up to the motor and the DCC bus. Additional wires are visible on the right that feed a turntable "spotlight" powered by an accessories bus.