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NCE decoder MARS Light Question

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  • Member since
    March 2004
  • From: San Diego
  • 954 posts
NCE decoder MARS Light Question
Posted by stokesda on Sunday, April 19, 2009 5:20 PM

I installed an NCE D15SR in my Athearn tunnel motor. I connected the nose light to the green wire and set it up for a Mars light effect. However, the function does not have a "steady on" option, it's either on as a Mars light, or off completely.

What I'd like to do is have it on like a headlight until the Mars function button is pushed (F1 in my case), activating the Mars function. Similar in effect to the "Type 1" ditch light function described in the NCE decoder manual.

Is there any way to achieve this with this NCE decoder? My first thought was maybe mapping a separate on/off function to the same output? I just wanted to see if anybody's done this or had any ideas about how it could be done. Worst case, I'll just have to live with it as is. It would be nice to be able to have it on and not "oscillating," though.

FWIW, I use a Digitrax Zephyr and Decoder Pro.

Thanks in advance.

Dan Stokes

My other car is a tunnel motor

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Sunday, April 19, 2009 5:25 PM

 You'll have to wire two functions to the light for this to work. And even then I don;t think you'll be able to make the steady light go off when you activate the Mars light function. It would work the other way - turn off the steady light and it flashes like a Mars light, turn on the steady light function and it's on solid.

                              --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    March 2004
  • From: San Diego
  • 954 posts
Posted by stokesda on Monday, April 20, 2009 11:59 AM

Thanks, Randy. What you described would be sufficient for my needs. If I wire two outputs to the same light bulb, I wonder if there is a danger of backfeeding one function when the other is on, thus shorting out the decoder? Has anyone done this kind of thing before?

Is there another comparable decoder that would let the Mars light have a "steady on" feature I described in my OP (e.g. Digitrax DH163 series)? I looked at the Digitrax decoder manual on the Internet and at first it looked promising, but after reading in more detail, I thought maybe not... it was kind of confusing to read and not easy to understand without having an actual Digitrax decoder to test the CV settings.

Dan Stokes

My other car is a tunnel motor

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Monday, April 20, 2009 9:08 PM

 I don;t knwo of any that offer what you want, steady on with function off, then Mars or other effect with function on, other than the ditch lights. Those can be set to be on, and then flash with F2 or other function, plus a holdover time. Most decoders with a ditch light option do this, but I don't think so when it comes to another effect like Mars or Gyralight.

 As for hooking two together - the blue wire is the plus common for all functions. Functions are sinks, not sources, so they are effectly switches to ground. Nothing comes out of the function leads that could feed back to another - all power is sourced through the blue wire. If both functions are on, it's just two parallel paths to ground. If you are worried, a diode in each function lead with the 'arrow' pointing to the function connection (cathode end to the F lead, anode ends tied together and to one side of your bulb or LED and resistor, blue wire to the other side of the light) will prevent any chance of there being a cross connection. But I don't think it's needed. Just make sure you do not exceed the current ration of any individual function lead - ie a lamp that draws 100ma hooked to a function that can only support 50ma loads - and it will be fine.

                                           --Randy

 


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    March 2004
  • From: San Diego
  • 954 posts
Posted by stokesda on Monday, April 20, 2009 11:21 PM

rrinker

As for hooking two together - the blue wire is the plus common for all functions. Functions are sinks, not sources, so they are effectly switches to ground. Nothing comes out of the function leads that could feed back to another - all power is sourced through the blue wire. ....

Oh, yeah... now that you mention that, I do kind of remember that little nugget of information from way back in the depths of my brain.

Thanks for your help, I might give it a shot one of these days when I get caught up on some more pressing projects/tasks. At least now I know I don't have to buy a different decoder.

Dan Stokes

My other car is a tunnel motor

  • Member since
    July 2006
  • 3,312 posts
Posted by locoi1sa on Tuesday, May 5, 2009 3:54 PM

 Dan

 While researching a decoder for a building lighting circut I came across the TCS FL4 function only decoder. Here is a download of the decoder instructions. It has the Mars light automaticly come on at 36% of speed and constant bright at above 36% throttle.

http://www.tcsdcc.com/pdf/update/FL4web.pdf

  Looks like this is what you need.

      Pete

 I pray every day I break even, Cause I can really use the money!

 I started with nothing and still have most of it left!

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