Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Have I Already Blown the LED, no Resistor?

492 views
7 replies
1 rating 2 rating 3 rating 4 rating 5 rating
  • Member since
    October 2016
  • 73 posts
Have I Already Blown the LED, no Resistor?
Posted by doublereefed on Thursday, January 21, 2021 11:02 AM

I'm working on a DCC/Sound install on Bachmann 2-8-0.  All is going well. Headlight doesn't work, finally performed the very important RTFM step... and it turns out that a 680 ohm to 1K ohm resistor is required when used with LED headlamp. I have arleady hooked it up and tried to turn on the headlight... have I blown that LED, or when I install the 1K resistor will it solve the problem?  

 

  • Member since
    March 2008
  • 382 posts
Posted by ba&prr on Thursday, January 21, 2021 11:05 AM

You fried the LED. So you need to replace it with a resistor in place.   Joe

  • Member since
    October 2006
  • From: Western, MA
  • 8,559 posts
Posted by richg1998 on Thursday, January 21, 2021 11:12 AM

I am sure you know now a 1K resistor is normal for an LED.

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
    October 2016
  • 73 posts
Posted by doublereefed on Thursday, January 21, 2021 11:29 AM
Ugh. Figured! Thanks for confirming.
  • Member since
    December 2004
  • From: Bedford, MA, USA
  • 19,698 posts
Posted by MisterBeasley on Thursday, January 21, 2021 12:18 PM

Maybe, maybe not.  If the LED  was wired backwards as well as missing the resistor, it might have survived.  When you turned it on, did you get one bright flash?  That's what happens when you turn a Light Emitting Diode (LED) into a Darkness Emitting Diode (DED).  If you got no flash, then maybe you lucked out because a LED doesn't do anything with the wires reversed.

The good news?  LEDs are cheap.

It takes an iron man to play with a toy iron horse. 

  • Member since
    September 2003
  • 15,494 posts
Posted by Overmod on Thursday, January 21, 2021 12:40 PM

Or you could do the equivalent of a quick coin-cell test on the LED to verify it's out.  We have threads that tell the best ways to do this, and people like Randy who have the best advice on how to conduct it now.

In the 'nothing happens by accident in this world of sin' category: you now have the ability to spec a headlight LED of a more suitable color or shape, or file its surround plastic down to mount it in a scale parabolic reflector, etc. -- I would have the mavens here recommend the best approximation to a 'Golden Glow' on that locomotive.  Not expensive, not particularly hard, and oh-so-good-looking!

  • Member since
    October 2006
  • From: Western, MA
  • 8,559 posts
Posted by richg1998 on Thursday, January 21, 2021 1:04 PM

Yes I did forget about the reverse connection. My bad. Some new users have done that. Proper direction is indicated with a search on the Internet.

I have never used an LED without a proper resistor, reverse or forward.

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 2003
  • 15,494 posts
Posted by Overmod on Thursday, January 21, 2021 1:32 PM

richg1998
I have never used an LED without a proper resistor, reverse or forwar

Moreover, it never hurts to put a 1K in on initial test, whether you 'know' there's an inline resistance in a board or not.  The LED will still show you the continuity, and you can then tell from the brightness if the inserted resistance is 'too much' ...

Subscriber & Member Login

Login, or register today to interact in our online community, comment on articles, receive our newsletter, manage your account online and more!

Users Online

There are no community member online

Search the Community

ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT
Model Railroader Newsletter See all
Sign up for our FREE e-newsletter and get model railroad news in your inbox!