If anyone has built a circuit to display train locations on their layout would you please share it. We have a large 24 x 55’ 3 rail layout with hidden track underneath the main level, and tracks that can’t be seen from the operating position. I would like to use LEDs or lamps on a panel to show me when a train is in a certain block. I’m open to wired or IR detection. Thanks, Dave
What you need to do is isolate the third rail of a piece of track. The 3rd rail is the rail that doesn’t have power or common ground from the transformer. I did this on one of my realtrax pieces. There are pictures in this week’s Sunday Photo Fun. Then attach a wire to that isolated section, and bring it back to the control panel area, or an area where engineers can see it if they walk around with wireless. Built a track diagram with AC lamp holes drilled in the diagram at the same place as the isolated track sections on the real track, like a map. Now attach that wire to the negative side of the lamp, and get the + from the same transformer that is powering the track. When a train passes that isolated section, the trucks will be grounded on the 1st rail like usual, and pass ground through it’s metal wheels and also ground the 3rd rail, which will send ground through your wire and to the lamp, lighting it up for as long as the wheel is passing over the isolated section.
If you want lamps to chase around the layout to show forward progression, then isolated a section, then give it a couple of feet of track without a ground wire, then isolate another track, and so on. If you want to just show that something is occupying the entire hidden section, then isolate the 3rd rail on the entire length. The light will come on when the train first hits the hidden area, and will go off when you see it again.
That is probably the simpiest and most reliable way to do it. My IR detection didn’t work too well, so I clipped the sensors and converted it to the 3rd rail detection. It was a very easy modification. With it, I gained a relay and a timer. For $20, this was nice as it gave me the ability to keep sending a grounded signal, even if the train wasn’t there, for a specified period of time. My isolated rail is only 3.5" long, but I can have it send ground for 0-15 seconds. It wasn’t require
An easy way to do this is to use GarGraves track as all three rails are insulated from each other at the factory, all you need to do is take out the steel pins and insert power clips on the section that you want to see where the train is located. 18 volt bulbs should work for this, led or regular incandescent bulbs, run the hot to the light bulb and catch the common or ground from the track section that is insulated. This is what I do for signal lighting on my layout to throw the red light on the track signal.
I have had trouble with IR detection signals, the train needs to be real close when it passes an IR device or it won’t work properly, also the shadow dissapears between cars and this messes up the IR device. Tried it for a siding on the main line and it kept flashing green to red as the train passed, so I wired the IR with an extra wire to a switch to show constant red.
Lee F.
There is no need to use the same transformer or transformer output that powers the track. Any voltage source with its return in common with the track transformer will do the job, and allow you to detect occupancy when the hidden train is stopped. I don’t know how to detect hidden rain on your layout…
I was thinking the same thing. I always get wet when it rains on the little people and trains on the layout. [:D][(-D][swg]
Surely the Layout Weather Service has a link to the Layout Weather Radar . . . .
A little over a year ago there was an article in the NMRA Scale Rails magazine about a circuit that uses photocells between the rails to detect the presence of a train. I think it was called the “Ten Minute Train Detector.” The detection circuit is powered with two AA batteries and powers an LED display. The circuit is very simple. The components are all readily available from Radio Shack. I am NOT an electronics expert, but I managed to build 6 circuits for detecting trains in hidden staging areas and they all work quite well. Also, the Circuitron DT-4 will do the same thing, although it runs on 12V DC and the ouput display is small incandescent lamps. Each DT-4 can detect 4 track locations.