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Powering 1.5 v lamp from DCC track power

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  • Member since
    June 2007
  • 196 posts
Powering 1.5 v lamp from DCC track power
Posted by Reformed Grownup on Tuesday, March 23, 2010 11:58 AM

I am nearing completion of my RS-11 DCC install and upon carefully reviewing photos of my prototype I realized that there is a MU receptacle w/ light that I hadn't accounted for when planning my install. I have everything wired up and all of the decoder's functions are occupied with other tasks. I came up with the bright idea (no pun intended) that since this light requires no FX and is a simple on/off lamp I could simply tap into the loco's track power pick-ups and wire up a 1.5v bulb with the appropriate resistor. I may add a small on/off switch if I can find something small enough. I am wondering if there is anything I should be concerned with with this approach. Things have gone suprisingly well to this point, so i don't want to blow it now!

 

Thanks for any and all insight.

Richard
  • Member since
    February 2002
  • From: Mpls/St.Paul
  • 13,788 posts
Posted by wjstix on Tuesday, March 23, 2010 5:10 PM

It should work, but you might look into using LEDs instead. I recall someone had an article in MR or RMC not too long ago about powering LED's for building lights from DCC track power. If you don't want to mess with adding resistors, you can get LED's with resistors already attached from Walthers.

Stix
  • Member since
    June 2007
  • 196 posts
Posted by Reformed Grownup on Tuesday, March 23, 2010 6:29 PM

I have a ton of GOR bulbs on hand, and no tiny LEDs, so I'll go with the bulbs. Thanks for the input. Now that you mention it I remember seeing that article, but I can't remember where...

Richard
  • Member since
    July 2003
  • From: Sierra Vista, Arizona
  • 13,757 posts
Posted by cacole on Tuesday, March 23, 2010 6:59 PM

Find a potentiometer of 100 KOhm to 500 KOhm range and connect one of your bulbs to a DCC powered track through the pot.  Start with the pot set to maximum resistance and then slowly turn it down until the bulb reaches an acceptable intensity. 

Remove the bulb from the circuit and measure the resistance of the pot.  Then use a fixed resistor of that value with the bulb permanently wired into the loco.  A GOR bulb should be able to get by with a 1/8 Watt resistor.  If the resistor starts to get hot, use a 1/4 Watt.

 

  • Member since
    June 2007
  • 196 posts
Posted by Reformed Grownup on Wednesday, March 24, 2010 7:26 AM

cacole

Find a potentiometer of 100 KOhm to 500 KOhm range and connect one of your bulbs to a DCC powered track through the pot.  Start with the pot set to maximum resistance and then slowly turn it down until the bulb reaches an acceptable intensity. 

Remove the bulb from the circuit and measure the resistance of the pot.  Then use a fixed resistor of that value with the bulb permanently wired into the loco.  A GOR bulb should be able to get by with a 1/8 Watt resistor.  If the resistor starts to get hot, use a 1/4 Watt.

 

Thanks I'll give this a try.

Richard

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