The Southern California Railroad Museum is one of the biggest transportation museums in the United States. One major feature of this museum is its Signal Garden. This allows guest to press a button and see signals work.

Behind the scene is a Linux Raspberry PI controller. This talk discusses how the 100 year old railroad signals are interfaced with the PI and the unique challenges that had to be overcome. For example, the "Wig-Wag" signals use two huge electromagnets which are continually turned on and off. Any time you turn off a big coil, you get a huge EMP which will fry unprotected machinery. Additionally there is the problem with dealing with systems that are over 100 years old for which the documentation was lost sometime in the 1930's.

The signal garden presents some unique challenges. Such as the time I started to upgrade the computer, opened the cabinet, saw the black widow making a nest on the main logic board, slammed the door shut and got some spray to debug the computer.