Looking for a train proximity sensor that would provide DCC AC voltage as the train passes by, else open circuit. I could use it to activate train signal lights. It would be nice if it would fit under the Bachmann HO scale track and get power from the track rails. I would like it to be as inconspicuous as possible. My train layout is atop the dining room table so I cannot drill holes into the surface.
https://www.digitrax.com/products/detection-signaling/bd4n/
Z-Stuff has exactly what you need and I have used their devices extensively.