Geoff Bunza's Low Cost DCC Controller/Function Generator for Animation, Test Tracks, Absolute Stopping Blocks for Keep-Alive DCC Locos.  Bare Board.  Geoff published this in his column in MRH as SMA22 and documentation can be found in the article.  Geoff provides design information including Gerber files, so you can easily have your own boards made, but we keep bare boards in stock and sell them in quantities as small as one, where economic orders at the board vendors usually require the purchase of several boards.

Geoff Says:

"Model animation—bringing models to life—adds enormously to the interest and enjoyment of any layout or individual model! This entry describes how to build what I call a “DCC Function Generator,” a combination of DCC base station and throttle for about $8 that can be used for mixed DCC animation control, DCC testing, Absolute/Emergency Stop blocking for lift-outs and bridges even for Keep-Alive equipped DCC locos, trolley multi-stop control, and all around DCC havoc!"

This is handy for a lot of DCC applications whether you use DCC, CMRInet, Loconet or some other layout control bus.