I completed a project called the "Trainsaver". It was detailed in the July 2006 issue of Nuts and Volts magazine. The device was used to control a "G" scale model train that was used in a BBQ restaurant. The train would wear out from running full-time, so I used a Prop-1 to manage the train and ad some fun sound effects. It also incorporated a motion detector to discover if any patrons were present. If no one was present, the train would not run.
Details, including the article (http://www.trainsaver.com/trainsaver.pdf), are here:
http://www.TrainSaver.com (http://www.trainsaver.com)
A picture of the device is here:
(http://www.trainsaver.com/gallery/thumbnails/dsc00924.jpg) (http://www.trainsaver.com/gallery/images/dsc00924.jpg) (http://www.trainsaver.com/gallery/thumbnails/dsc00926.jpg) (http://www.trainsaver.com/gallery/images/dsc00926.jpg)
click to enlarge
I'm happy to answer questions. :)
Vern