Thursday, January 5, 2012

Cheap & Simple N Scale Signals Using Fiber Optics

I built several simple and cheap signals for my Rocky Mountain Sub model railroad several years ago that used bi-polar LED's powered from Tortoise switch machines and fiber optics to channel the light up through a metal tube and out the signal mast.  I thought I would share some photos of how I accomplished this.  While they don't operate like a prototype signal, they are very easy and inexpensive to build, and offer an interesting and unique feature to a model railroad.  I built these almost 7 years ago, and today there are a lot of other signal options available using tiny LED's mounted directly on the signal mast and wired to a variety of electronic components. 

First I took a short strand of fiber optic and heated one end with a lighter to make it round like a bulb.

Next, thread the fiber optic into a short piece of hollow alumimun tube.  The tube was cut at a 45 degree angle on one end, and once the fiber optic is inside the tube, I form a 90 degree bend.

The mast target is created from a peice of styrene cut out using a hole punch. 

The target is slipped over the tube and glued in place.

The top of the mast is painted black.  Here are several signals ready to be installed.

I use bi-polar LEDs to light the signals.  I drill a hole in the end for the fiber optic strand.

Here I am testing a signal by holding the other end of the fiber optic over the green LED on my computer keyboard.

The LEDs are wired to a Tortoise switch motor to change polarity when the turnout is moved.  This motion changes the signal from red to green and vice versa.

Here are two working signals on the Rocky Mountain Sub model railroad.


  1. Now that is a clever idea. With the price of mini-LED's, this is a very cost effective solution.

  2. What is the tube size and sizing for the hole punch, thanks

  3. that is great, thanx for the idea

  4. if you are using foam benchwork, a good idea to prevent light pollution is to glue black plastic tubing (or any opaque tubing) pieces into your scenery beneath the signals to shroud the LED generators and keep them from lighting up your scenery or to keep distractive under-bench lighting from occurring. good job on the signal hack.