A model train display just does not seem complete without the addition of signals. Unfortunately, the cost of such signals can be very prohibitive for the standard model builder. If this is the case for you then why not just build your own? You can pick up the parts as you have a bit of extra money and then when you have them all you can assemble and install them onto your display.
As an example for this article we will use an H0 scale model. At the end you will find a list of necessary supplies to build this particular setup. One warning: if you are just getting into model train building and have very little experience in working with electronic components then this article is not for you unless you want to take the time to learn a bit more about the subject before you get started.
The first thing that you would need to do is to create a base for your signal. A piece of .080" styrene will work for this size model. Cut your base out and set it aside. Now you will cut your stack base to go on the top of this. As you cut out your pieces you stack them one on top of the other. These pieces should be 4'x6' in size and should stack until about 6' in height. The next step is to add a piece of 3' square styrene with the edges beveled off to the top of this stack. Once you have all pieces cut you will cement them together along with the base itself.
Once thing you might want to do for ease of use is to sand any sharp edges off of the stack and smooth it out before you cement it to the base. When you do add it you need to make sure and center it properly. Now you are ready to cut a door for your signal. Use a piece of .020" styrene that is 3' square and cement it to the side of the base that faces away from your track. You can also add little pieces of styrene as hinges and a piece of .015" brass wire will work perfect as a door latch.
The next step is to drill a hole through your stack. Make sure it is centered in the middle of the 3' piece of styrene and use a #22 drill. If you go too fast you will melt the styrene so go slow and take your time. Solder your 1/8" and 5/32" pieces of brass tubing together. The 1/8" piece should be just inside the top of the 5/32" piece when you solder it. Slide the assembly through your stack until only a small bit of the large tubing is showing out the top of the stack base. The bottom needs to be just long enough to penetrate your table display. The top pole should be cut off to 20' in H0 scale. If you choose you can add a styrene point to the top of the pole.
Next you need to cut a piece of the 7/32" brass tubing at a 30 to 45 degree angle and leave it about 1/4" long. The square cut end of the tube needs to be inserted into the center of the #10 washer. While your LED may have to be slightly filed down for a good fit it should then fit into the center of this assembly which makes up your head. Make sure to glue everything together from the back of the signal. Now you must decide where on your mast you want to mount your signal head or heads if you choose to make more than one.
Use a round file to notch the back side of the mast and then glue the head to the mast. Take and bend one of your LED light's leads so that they touch the mast and solder it into place. Solder a piece of telephone wire to the other lead and run it through the mast via the notch.
At the bottom section of brass tubing underneath your searchlight you need to add another wire that will act as the circuit common for all the heads you have attached. The next part is very important, if you do not connect it correctly it will not work and could be a fire hazard. If you are using 5 volt TTL signal logic you should add a 180 ohm resistor in series with each wire going to an LED. Use a 510 ohm resistor if you are using 12 volt logic. You will need to add the Walthers signal bridge ladder stock on the backside of the signal mast. Also there are many masts that are marked with a letter "A" that you can add via a piece of styrene cut to shape if you so choose.
You can now paint your signal. The head should be black and the rest will be silver. Once you reverse polarity your LEDs will switch between red and green. While your new signal might be a bit larger than scale it should not be noticeably so. Enjoy!