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Resistors for Athearn 1.5 v bulbs

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  • Member since
    December 2011
  • 72 posts
Resistors for Athearn 1.5 v bulbs
Posted by NSDash09 on Wednesday, July 4, 2012 2:45 PM

I decided to put miniatronics 2mm tower leds in my Phase III heritage p40DC for both the Headlights and ditch lights. I am also getting a Loksound V4 decoder from Litchfield with their custom AMD103 sounds. Ifthe Loksound V4 does not come with a 9pin plug then i think i will hardwire the entire loco because the leds with resistors need ~14v and without they need 3v (vs athearn's stock 1.5v). I wanted to leave the backup lights the way they are so i would need resistors for them. Does anyone know A: if the V4 has / does not have  a 9 pin plug and B: what resistors should i use to bring the 14v down to the 1.5v. I do not know the current so V=IR doesn't really help me. They are stock athearn bulbs on a RTR light board with DCC quick plugs (both 8 and 9 pin). Thanks.

  • Member since
    February 2002
  • From: Reading, PA
  • 30,002 posts
Posted by rrinker on Wednesday, July 4, 2012 4:53 PM

Remove bulbs, use LEDs, with 1K or larger resistors. The bulbs likely won't last long anyway.

It depends on which version fo the Loksound V4 decoder you are getting. The Athearn/Atlas form factor one replaces the stock circuit board, it does not have a 9 pin plug.It does have resistors for LEDs already on board, depending on which connection you use for the common.

                  --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
    December 2011
  • 72 posts
Posted by NSDash09 on Wednesday, July 4, 2012 9:48 PM

Do you have any recommendations as far as leds? The tower leds I have are quite bright... i feel as though they will blast whatever is behind it while in reverse.

  • Member since
    October 2006
  • From: Western, MA
  • 8,571 posts
Posted by richg1998 on Wednesday, July 4, 2012 9:55 PM

NSDash09

Do you have any recommendations as far as leds? The tower leds I have are quite bright... i feel as though they will blast whatever is behind it while in reverse.

Some people increase the resistance to cut the brightness.

Richmond Controls has some nice LED's. The SMD type can come with wires already soldered to them. Great for marker lights.

Rich

If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Thursday, July 5, 2012 5:32 AM

Use higher ohm resistors to cut the brightness down.

If you don't replace the Athearn incandescent bulbs with LEDs, at least replace them with Miniatronics 1.5 volt bulbs.

Rich

Alton Junction

  • Member since
    December 2011
  • 72 posts
Posted by NSDash09 on Thursday, July 5, 2012 6:49 AM

what resistors do you use with the miniatronics 1.5v lights? Do they tell you or do you find out by frying a few? Also, I bought some model power 1.5v lamps for the marker lights. They were the only thing that the local hobby shop had. Should i order some miniatronics to replace them or are model power bulbs okay?

  • Member since
    September 2004
  • From: Dearborn Station
  • 24,281 posts
Posted by richhotrain on Thursday, July 5, 2012 1:27 PM

I use 1000 (1K) ohm 1/2 watt resistors with the Athearn 1.5 volt bulbs.  That seems about right. 

If you want the bulbs brighter, you could step down to resistors in the 700 ohm range. 

For dimmer bulbs, try the 1500 (1.5K) ohm 1/2 watt resistors, but those seem too dim for my liking.

You will get similar results with the LEDs.

Rich

Alton Junction

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