Adding Lights to Model Locomotives With DCC

  • 01 of 05

    Adding Extra Lights

    Ditch lights and lighted number boards add a realistic touch to the front of this F40PH model. Ryan C Kunkle

    Most model locomotives have at least a headlight and backup light. Real locomotives often have much more. Lights serve many functions on a locomotive, from illuminating the path ahead and warning the public, to signaling other trains and providing a safe work area for the crew.

    Adding these extra lights to models adds realism and interest. With today's DCC and Command Control systems, these lights can perform realistically and be controlled independently.

    Most DCC decoders can control a variety of lighting effects. From flashing strobes and Mars lights to modern ditch lights which flash in conjunction with the sounding of the horn, to marker and class lamps, even walkway and cab lighting.

    While the lights perform differently and may be located in different places, all of these lights can be created with the same basic steps.

    What You'll Need

    To add lights, you'll need a decoder. Choose a decoder that offers enough lighting outputs for the functions you'll want to add. It is usually the number of effects you want to create, not the type of effects, that will determine how many function outputs and the type of decoder you want.

    For example, if you only want a headlight and backup light then just about every decoder will get you what you need. If you want to add marker lights, that's an extra function. Want class lights and a rotating beacon on top of the cab roof? That's two additional functions. Ditch lights can be one function if they don't flash ​but will be two if you need to create the alternating flash pattern used at crossings on some railroads.

    In addition to the decoder, you'll also need lights. You can use incandescent bulbs or LEDs. Today, most modelers are choosing LEDs for their lower current draw, lower heat, brighter light and longer life. Since space is at a premium and changing these bulbs can be a challenge, this can be a real advantage. Except for checking the polarity on LEDs, the following steps will work for either.

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  • 02 of 05

    Installing the Decoder

    Decoder Installation
    Space is at a premium in most models. Install the decoder first to locate the rest of your components. Ryan C Kunkle

    After selecting the decoder, install it in the locomotive to ensure you'll have enough room to install the lights. Follow the standard steps for a decoder installation, including attaching the track pick up and motor leads to the correct decoder wires. On many DCC-ready models today, installation is as simple as plugging it in.

    Use the blue, white and yellow wires for your headlight and backup lights. This is a great time to convert these lights to LEDs as well if they aren't already.

    Before you add extra lights and functions, it's a good idea to test the decoder to make sure you've got the basics covered.

    Your extra lights will also use the blue lead as a common (positive) lead. The other lead from your additional lights will go to one of the other wires or tabs on the decoder. Typically green and purple are used for the first two of these functions. For decoders that offer even more options, you'll typically have to solder connections to the decoder itself. Choose a wire color that won't cause confusion if you have to trace problems later.

    If you have multiple lights which will always operate at the same time, these can be wired to one lead. A common example of this would be number board lights at the front and rear of the locomotive. Any lights which must have independent control will require their own lead and function.

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  • 03 of 05

    Installing the Lights

    Light Wiring
    When adding LEDs, make sure all wires are properly insulated. Ryan C Kunkle

    Lights can be added to their proper location on the shell or located elsewhere in the interior with the light transmitted to the proper lens with fiber optics. How you go will depend on the type of effect you want to create and the room you have inside the model.

    For the marker light installation is shown here, fiber optics made the most economical choice. One red LED illuminates both front markers and a second controls the two in the rear. 

    A resistor must be soldered between the decoder and LED. For most applications a 1k Ohm 1/4 Watt resistor is appropriate but you should check the specs included with your decoder and LED. You can wire the resistor to either lead.

    Attach the anode, or positive lead, of the, LED to the common blue wire. Attach the cathode, or negative lead, to the function output wire of your choice.

    Use heat shrink tubing to protect all of your solder connections. In these tight spaces, bare wires are an invitation for short circuits and disaster.

    If using fiber optics, heat shrink can also be used to attach the strands to the LED. Avoid using direct heat to shrink the tubing here however so that you do not melt the fiber optics themselves. 

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  • 04 of 05

    Routing the Wires/Fiber Optics

    routing lights
    Route light wires or fiber optics carefully to avoid pinching between the body and frame. This can be the most challenging part of your project. Ryan C Kunkle

    You will have to route either the fiber optic strands or the wires for the lights back to the decoder. The installation shown here uses fiber optics, but the process is much the same either way.

    You may need to mill away parts of the metal frame of the locomotive to get the wires/strands where they need to go without pinching them against the shell. Each project will be a little different.

    Since these auxiliary lights aren't as commonly applied on ready-to-run models, you may have to make some modifications to the shell as well such as drilling holes or adding detail parts.

    If possible, make the wires/strands a little longer than needed and then trim to length once the shell is in place. If the wires or strands will be seen through windows or open vents, paint them flat black.

    In the photo above you can see the fiber optic strands for a pair of marker lights extending out of the nose. The lights themselves were made by inserting a small piece of copper tubing into holes drilled in the body. The optics are painted black where they pass through the cab to block the light. After the shell is installed, the strands can be cut to length.

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  • 05 of 05


    LED Lights
    LED headlights and marker lights add a realistic look and long life to Athearn locomotives. Ryan C Kunkle

    With the lights installed and the shell in place, all that is left is to program the decoder to create the lighting effect you desire. Most decoders are capable of producing a variety of effects. The wiring is the same whether you want the lights to just turn on/off or pulse like a strobe - it's all in how you program it. Follow the instructions included with your decoder to program the lights you want.

    The red marker lights in the locomotive shown here can be turned on or off independently of the headlights. A similar set of lights on the rear of the locomotive is also independently controlled.