There are a choice of manufacturers that make controllers. (They are often called “throttles” by manufacturers.) At an early show we met a group who were showing DCC Ex which created documented protocols that could enable the construction of one’s own controller using an Arduino with a motor shield to provide the necessary power to the track. All the software for the Arduino was provided by the DCC Ex group free. 

This was very attractive as it used DCC. (How DCC works is described in a separate menu item.) Although there was a web based controller available, Mike decided to program his own as the project was likely to need more functionality that the web based controller offered. There was a fairly steep learning curve, but the DCC documentation was very thorough and the email support from the group was excellent.

Below is an image of the Arduino with its motor shield. It has the release version of DCC Ex loaded.