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DC Marx HO wiring Help!

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  • Member since
    September, 2017
  • 1 posts
DC Marx HO wiring Help!
Posted by Safety Valve on Tuesday, February 05, 2019 8:00 PM

Hi I've been wanting to retrofit a Marx HO 0-4-0 tender locomotive to have a modern DC electric motor, I have 6 I bought off amazon, by EUDAX they are 12 volts DC... I bought the train set for $40 off eBay, the motor in the set didn't work at all, it was a non runner.

I wanted to add a resistor and eventually and LED to the "running board", I have some ideas that I'd like to do to the engine, but that's for diffrent discussions on diffrent parts of these forum threads.Wink

I have been having a hard time finiding the "right" wiring diagram to use for wiring up the locomotive... (I have been thinking about even using a diagram from the RC car industry, but so far I haven't been a whole lot successful) I'm not sure where else to look. 

I am not sure a 10kohm resistor would work??? I don't really want to fry the resistor and the light. I have a variety of resistors to use that I got for $10 on Amazon, 0ohm to 1Mohm 

Any help would be appriciated.Smile I am a bit of a newbie in this. I am Not new to the Hobby, but new at wiring locomotives from scratch.

                                                                                   

  • Member since
    May, 2010
  • 4,085 posts
Posted by mbinsewi on Wednesday, February 06, 2019 12:10 PM

There have been lots of modelers in here that have repowered their locos, even small ones like yours, and I'm sure someone will pick up on this and help out.

Is the Marx and DC now?  I know nothing about them.

Mike.

  • Member since
    January, 2009
  • 3,394 posts
Posted by RR_Mel on Wednesday, February 06, 2019 12:21 PM

A 1KΩ resistor should work OK for a LED headlight.  You’re not going to fry a ¼ Watt resistor over 580Ω at 12 volts or a ½ Watt over 280Ω.  That is there max rating at 12 volts
 
 
 
 
 
 
Mel
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
  • Member since
    December, 2015
  • 4,616 posts
Posted by BigDaddy on Wednesday, February 06, 2019 12:28 PM

The old motor got power from somewhere, one side of the loco and the other side of the tender was a common way to do it.  Those power sources are the feeds for your new motor.

A bulb could tap into those power feeds and you would be good to go.  The LED is a bigger problem, because there is a polarity that must be observed.  If the power is backwards, it will not light and may damage the LED over the long term.  This was recently discussed in lighting passenger cars or cabeese, but since I do not run DC, I did not pay attention.

For DCC, a 1K resistor is plenty, and it does not matter to which lead of the led it is connected.

Henry

COB Potomac & Northern

By the Chesapeake Bay

  • Member since
    October, 2006
  • From: Western, MA
  • 7,935 posts
Posted by richg1998 on Wednesday, February 06, 2019 12:48 PM

Many years ago I used a constant voltage lighting circuit with a 1.5 volt bulb and a four diodes. It produces 1.4 volts DC. Never tried it with a LED which requires around three volts.

http://www.mrollins.com/constant2.html

Rich

N

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