Have you been looking for a signal telling you what to do? Well, here’s one!
I’ve posted about the DCC decoder for this before, but never the finished signal, and it was time to change this. So here it is, in all its glory. This signal I’ve built is in 1 gauge or G gauge, intended for garden railways (LGB and the like). Though it isn’t weather proof at all, and I’m not entirely sure how to mount and connect it so that it’s easy to bring indoors every time you’re done playing. Also the loop of track I have on my balcony isn’t actually DCC controlled. In reality this is mostly a test and hobby project rather than something I’m definitely going to use anywhere.
The prototype for this is an American searchlight signal, by now an outdated type that I think looks really nice. Since I’m lazy I decided to go for a simple single-head version. As the video shows, mine can show red, green, yellow, and „lunar“, a blueish white. Plus, it can flash its light.
In reality, an actual signal of this type can only show three colors at most, and the railroad decides which one it needs at any given point. This type of signal has only one lamp inside, and then a solenoid that can switch between three different color filters: One setting puts the left filter in front of the lamp, one setting puts the right in front of it, and no power means a centering spring puts it to the center position, which is thus generally red. A side-effect of that is that when you go from one non-red color to another, you’ll get a brief flash of red in between, because it’s moving from the left to the right filter or vice versa, and will briefly show the middle one in between.
I’ve based this on this video: https://www.youtube.com/watch?v=ic1vkBMlPxs The actual colors in that video are shown from 5:25 onwards. My single-head signal is essentially the same as a two-head signal whose bottom light is always red (or as a three-head signal whose bottom two lights are always red), so all of the combinations that are shown with the bottom light red are also ones that I can show.
The LED showing the color is an individually controllable „Neopixel“ type, which means it’s very easy to add more signal heads without adding many more wires. In theory the number is unlimited, but in practice I’m limited by the power supply in the DCC decoder, which uses a standard inefficient 7805 (specifically an UA78M05) and gets warmer than I like already. Two should be okay, three might be pushing it (which would be a good reason for me to redesign the decoder to use a switching converter).
The decoder fully supports DCC, including programming mode and programming on main. Okay, technically I have a bug in there and I haven’t yet bothered to get the decoder out and install the fixed software on it, but in theory it all works. It does not support Railcom, though, because that’s a whole other can of worms.
The actual hardware signal is 3D printed, using the HP plastic setting at Shapeways (I picked their „first available plastic“ option and this is what they gave me). It is all one integral part, which is, in retrospect, a huge mistake. Fitting the wires in was difficult, fitting the LED in was a nightmare, and in fact even now it’s not perfectly straight but rather tilted upward. Next time I’ll redesign this to be multiple parts that I glue together later, for easier access.
Of course the real challenge for next time will be to get this all into N scale, then using 2x2mm „Neopixel“ LEDs. (I’ve not picked the 1.5x1.5mm ones because… well, honestly, I didn’t know they were a thing when I bought my supply of 2x2 ones). They only use 5mA, so I think in that case power supply will be far less of an issue.
All in all, I’m really happy with how this turned out. But I already have a long list of things to differently next time.
