# DCC in a USA Trains Hudson



## trunstrom (Jan 28, 2009)

I am installing a NCE 808 decoder in my USA Trains Hudson that came equipped with a Phoenix 2K2 sound system. Does any body know the voltage and current rating for the lights on this loco? It seems that there may be as many as four different sizes. Head and backup lights, running lights, cab light and firebox lights. I am expecting that I am going to have to add resistors in line with the lights.

Thanks for any info.
Tom


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## Treeman (Jan 6, 2008)

You may want to power it up and check the voltage going to lights with track power. It seems hard to get that information from USA but you may find someone here that has done one.


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## Bill Swindell (Jan 2, 2008)

Headlight is 5V, Markers are 3V


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## trunstrom (Jan 28, 2009)

Sorry, I am a little late in seeing this last reply. Do Marker Lights include the cab light and the firebox lights as well? Also, since I am still struggling to get to a comfort level with decoder installation, I believe I need to know the amperage draw of these lights to install the proper dropping resistors. Do you have that information as well?

Thanks,
Tom


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## Greg Elmassian (Jan 3, 2008)

Not only should you know the amperage, but resistors are usually a very poor approximate way to limit voltage in a light bulb. (Great for LEDs though). 

I'd consider 2 voltage regulators (one 5 and one 3) and then no resistors are needed 

Greg


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## Bill Swindell (Jan 2, 2008)

I used 2 regulators when I did it.


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## Dan Pierce (Jan 2, 2008)

Tom, look at the LM317 adjustable regulator as you can use resistors to create 3 volts and many USA engines have devices these in them, sometimes 2 of them. 
This is how they get 3 volts for the lights. 
When I did an engine, I used the 6 volt regulator and tied pairs of lights in series. This makes the heat generated by regulators to less than half. 
Current is half, but voltage dropped is 3 volts less, thus less heat and using the LM7806 is easier than using the LM317 with resistors.


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## trunstrom (Jan 28, 2009)

Thanks guys! It looks like I need to make a trip to Radio Shack to see what they have in the way of voltage regulators. SLOWLY I am starting to learn. Beats burning out light bulbs or LEDs.

Tom


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## Dan Pierce (Jan 2, 2008)

TOM, I have 6 volt regulators and I will bring 2 of them to the Lunenburg meeting today.


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## Greg Elmassian (Jan 3, 2008)

but he needs 5v and 3v .... the 5v you can find, the 3v will need an adjustable reg. 

Greg


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## Dan Pierce (Jan 2, 2008)

Greg, you can place the 3 volt marker lights in series and use the 6 volt regulator which is easier than trying to figure out the resistor values for the adjustable regulator, plus if using a heat sink, the 5 volt and 6 volt units can have the same ground. 
The adjustable regulator would need isolation as the tab is not ground. 

And I do know how to get the resistor values for the LM317, but for others the 6 volt method can be easier. 

And I did warn Tom that the Hudson metal chassis could be a problem if the regulators were not isolated from the metal chassis as this would make the chassis become the decoder minus and a derailment could short the decoder. The Aristo metal cars come to mind as they use one rail tied to their metal frame.


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