Athearn Genesis SD70M and NCE decoder

Discussion in 'HO Scale Model Trains' started by Nick8564, Feb 15, 2006.

  1. Nick8564

    Nick8564 Member

    I have the Athearn Genesis SD70M with a NCE decoder(DA-SR) in it. Im trying to hook up the lights in it. It also has ditch lights. I have 1.5V 30mA 1.2mm lights for front, rear and the ditch lights. I hooked them up with 470 ohm resistors and blew everyone. I hooked them up with 1k ohm resistors and no light now. Radio Shack doesn't sell anything in between. Should the front and rear lights be hooked up to one resistor, or should each one have its own resistor. Thanks
  2. eightyeightfan1

    eightyeightfan1 Now I'm AMP'd

    Instead of changing resistors, try using a higher voltage light bulb.
    Sometimes, the maker of the decorder, recomemnds a higher voltage light bulb.
  3. sumpter250

    sumpter250 multiscale modelbuilder

    First, you should contact NCE about the voltage output of their decoder's light circuit.
    Second, each bulb will draw .030 amps(30ma). If you use one resistor for all, (two headlights,two backup lights, two ditch lights) you have to choose one that will permit 180ma of current, at the operating voltage. At 18 volts, 100 ohms. At 12 volts, 67 ohms. Individual resistors for each bulb, at 12 volts, 400 ohms. At 18 volts, 600 ohms.
    If you use one resistor for each pair of bulbs, it will be half the value . ie.two bulbs at 18 volts,300 ohms. This, however will allow an overvoltage on one bulb, if the other burns out...if one goes, both go!
    I usually wire each bulb to its own resistor, and hook up with a wirewrap tool.

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