Excerpts from a recent interview between Keith Waddell and Gerry Nelson on developing a working railroad crossing signal:
Keith: Now we’re going to talk a little about the crossing signal that’s been installed by Jerry Nelson and by Louis Frank. So, Jerry do you want to tell us how this was installed.
Jerry: We decided that when people first come in and look at the layout they could see a road crossing right there on the layout (its the first thing people see when they enter the room), but we had fake road crossings, just x’s there. So we bought the machines including the electrical board, and Louis got it all set up for me and I went and drilled the holes and installed everything. Initially we had flashing red lights, but we had no bell so we got a hold of a guy in Nevada who built us a bell system, and I just installed it. So that now when a train comes the lights flash and the bell dings and its really nice.
Keith: Great! I do have a question : for the flashing lights, is this a commercially available board?
Jerry: The board that makes the lights flash is commercially available and made by Circuitron.
Keith: And the board for the bell was made specifically by ….?
Jerry: a guy in Nevada, his name is Werner Vinson of Vinsons Custom Electronics.
Keith: The system is automatic, so how does it work?
Jerry: There’s two lights and eight little light sensors. The light sensors are in the track, two when it comes on, two when it goes off, that’s four, then there’s two tracks so that makes eight sensors. Then an electrical circuit board for the lights, and an electrical circuit board, another one, for the bell. (Ed: a light sensor normally detects light, when a train passes over the top of it, the light dims and this triggers the circuit to turn on. Another light sensor on the other side of the crossing detects dimming light when the train has passed it and turns the circuit off.)