Secure Site

Shop with


Search Site
Lighting Products
Lighting Accessories
Lighting Effects Products
Lighting Kits
Little Sounds
Photo-etched Products
Stamped Metal Products
Other Detail Stuff
Soldering Aids
Other Cool Tools
Tips 'n Tricks
Ordering & Delivery Info
Join Our Mailing List

Best viewed using:

 Internet Explorer


Mozilla Firefox


Connecting the N8039 Steam Locomotive Class Light Simulator


Installing the N8039 is very straightforward. Its tiny size and thin construction will allow it to be placed in many spaces too small for even the smallest Z-scale decoder. Because the module has circuitry on both sides, care must be taken to be sure that the components or wires soldered will not make contact with any metal object (such as a locomotive frame) causing a short circuit.

If the N8039 is to be used in a stationary (not track powered) application, it can also be powered by any well-filtered and regulated DC power source with an output of 6-18VDC.

Included with the module are three 6” lengths of #32 insulated wire. If necessary, these can be used for power input and function control wires.

Most wired decoders have a blue wire which is the common connection for all wired functions (F0, F1, etc.). It is the + DC connection and will be connected to solder point #1 as shown in Fig. 1.

If the decoder is a “drop-in” style without wires, consult the decoder manual and use the blue wire supplied to connect point #1 to the appropriate + solder pad.

                                Figure 1

If the solder pad has a resistor in series with it, be sure to connect the blue wire behind the resistor (see Fig. 2). This will ensure full voltage is supplied to the module.


                                Figure 2

Important note: A low-wattage iron with a pointed tip should be used for connection of wires. Too much heat or solder can easily damage the wires, decoder or module and void the warranty.

Also, all connecting wires should be pre-tinned before soldering them to the module. This will make connection quick and easy and ensure excessive heat is not applied to the solder points.

Next, choose the function you want to control the N8039 module and connect the appropriate function wire to solder point #2. For example: If you want F1 to turn on the Class lights, connect the green wire to #2.

Again, if the decoder is the drop-in style, use the enclosed green wire to connect the appropriate function solder pad to #2. Make sure the pad chosen for this connection is not a “+” pad , but a function pad (– DC connection).

Whichever function you choose, make sure it is programmed for On/Off control only. Do not program the function for special effects. The N8039 will control the special effects.


Direct Track powering (without a decoder connection)

All of our Simulators require a clean DC voltage of known polarity for their power source. Track power is typically provided in one of two forms. DC voltage (analog), or DCC.

Analog track power has been around for more than 75 years. Simply put, a DC voltage is applied to the two tracks with one being +DC and the other, -DC. Increase the voltage and the electric motor in the locomotive spins faster making the train go faster. If the train is required to reverse, track polarity is reversed so the loco's motor turns in reverse. Also, what defines "forward and reverse" is dependent on which way the loco is facing when it's put on the track. Bottom line here is that track polarity is not fixed. Our Simulator needs fixed polarity.

DCC track power is such that to devices requiring plain DC voltage, it looks like AC power. That is because voltage levels on each track go both + and – continuously. The DCC decoders in locomotives “descramble” the track signals and provide correct polarity so their motors can function normally. It is this process that will allow multiple locomotives to go in different directions on the same section of track, at the same time (a feature not available with analog track power). Once again, our Simulator needs fixed polarity and it needs to look like DC voltage.

Due to our Simulator's very small size, there is insufficient space to include additional circuitry and components necessary for proper power conditioning when direct track pickup is to be used. There are two solutions to this problem and both are inexpensive:

Discrete components

The Simulator can be powered from the track with the addition of two readily available components: a bridge rectifier (our N301S or N302S will work just fine). If DCC operation is used, the addition of a filter capacitor (10μf or larger and minimum 16-volt) will be required. Figure 3 below is schematic diagram of the connections required.

                                             Figure 3

This is the least expensive solution, but is has a couple of minor drawbacks. First, the bridge rectifier (and capacitor, if needed) are not mounted on a circuit board so direct solder connection is required and you will need to ensure the pins on the rectifier and leads on the capacitor (depending on the type of capacitor) are organized so that they won't short out against anything. Second, depending on the physical size of the bridge selected (and capacitor, if needed) and the scale you're modeling, hiding these additional components so they're not noticeable can be a bit of a challenge.

N8101 DC Power Source

A more elegant, but very slightly more costly ($3.95) solution would be to use our N8101 DC Power Source. It has all of the components needed, includes a circuit board with solder points, is extremely tiny (1/2 the size of our Simulator), has the lowest possible voltage loss (important for analog operators). Click here for more information on the N8101. Figure 4 below is schematic diagram of the connections required.

                                               Figure 4 

Connecting LEDs

When connecting the LEDs, proper polarity must be observed. LEDs are “polarity sensitive” and will not function if connected backwards. The N8039 is configured to allow the connection of two (2)  20 ma green LEDs (wired in series) with device voltages of 2.2-2.25 VDC. This covers Ngineering’s Micro and Nano green LEDs, as well as many green LEDs available.

Using wire appropriate for the size of the LEDs and its placement in the locomotive, connect the two green (series wired) LEDs to the simulator module as shown. Remember, series wired LEDs are always connected anode to cathode. Connect the cathode wire (the – connection) of the series pair to point 3 on the module and connect the anode wire of the pair (the +) to solder point 4. These LEDs will use the on-board 23Ω current limiting resistor so they can be wired directly.

The next two (2) LED connections will be for the white class lights. Each LED must be wired with an external resistor in series to limit the current flow through the LED. These two LEDs cannot be wired as a series pair due to their combined higher device voltages so each must use its own resistor. Included with this module are several 1/8-watt surface-mount resistors (we’ve included a spare just in case) selected to reduce the brightness of the white LEDs to be closer in intensity to green LEDs (which are typically lower in brightness). This will maintain a reasonable balance in class light intensity when switching between effects. These resistors are tiny for easy placement and have pre-tinned tabs so soldering is easy. The first white LED’s cathode is to be wired to solder point 5 on the module. The resistor should be wired in series between this LED’s anode and point 6. The second white LED's cathode is to be wired to solder point 7 on the module. The resistor should be wired in series between this LED’s anode and point 6. See Fig. 5 below for a complete overview of wiring.

                                                                      Figure 5


Once again, be sure to use a low-wattage soldering iron when connecting wires to the module. Our N40M2 12-watt Iron with either the N408I (iron clad) Needle Tip, or the N408X (bare copper) Needle Tip would be an excellent choice for this operation (or any DCC decoder work).


Input control

Solder point 8 on the simulator module is for connection of the control or function input wire. With a DCC decoder installation, this can be connected to either a momentary throttle function such as F2, any on/off decoder function (F1, F3, F4, etc.). This simulator can handle either type of control input. If an on/off function is selected for hookup, be sure the decoder has any special effects turned off for that function. The simulator module will take care of the effects.

For non-decoder installations or for analog operation, solder point 8 can be connected to any switch (momentary pushbutton or magnetic reed switch) which is tied to -DC (ground).


This completes hookup of our N8039 Steam Locomotive Class Light module. We hope the added realism it provides enhances your enjoyment of the hobby.


For a details on the operation of this simulation module, choose Operation form the More Info table on the Lighting Effects Products page, or click here.




© 2008 Ngineering