@mike g. posted:...
Stan, I like your idea, and I would be interested if it was all just plug and play. I would even be willing to try and build a cabinet for it that might look more realistic.
I do have one question though, how do you think this would work with 3 or 4 tracks within the same range?
Well we have at least one brave soul! 
Yes, it will be plug-and-play. You apply accessory AC to the 2-terminal connector...and then attach 2 or 3 wires (depending on your accessory) to the 3-terminal connector. No soldering required.
The unusual thing about this ultrasonic detector is the sensitivity is very precise in terms of distance to target. So if you have 4 parallel tracks, you should be able to set the detector to trigger on the closest track ONLY (ignore 3 distant tracks)...or the 2 closest tracks ONLY (ignore 2 distant tracks)...or the 3 closest track ONLY (ignore most distant track).
Obviously, those guys that are able to wire the parallel tracks using the insulated-rail method can effect similar precision on which track(s) trigger an accessory. This method has the sometimes useful benefit that in can be done after-the-fact so you don't have to rip-up carefully ballasted track. It also applies to 2-rail or situations where you might not be able to use the insulated-rail method.
As GRJ alluded to earlier, it's not clear how much interest there is in this "new" technique. I'm particularly interested in guys that might discover some specific applications where the ultrasonic method is particularly well suited. Sort of like the topic of this thread in the first place...where the ultrasonic method turned out to be particularly suited for an outdoor layout.
