need help with right size resistor for the led's I bought ?



Ahhh.... that explains everything - problem solved!
Hope it all works when you get back.
David.
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Right news group + Right resistor + right led + right decoder wire my first successful full locomotive convertion to DCC. Thanks again guys :) now can I use just one resistor on the common wire instead of one coming off each led ?
E. T. Atkins wrote:

--------------060100000300030801050000 Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> <html> <head> <meta http-equiv="Content-Type" content="text/html;charset=ISO-8859-1"> <title></title> </head> <body text="#000000" bgcolor="#ffffff"> Right news group + Right resistor +&nbsp; right led + right decoder wire&nbsp; my first&nbsp; successful full&nbsp; locomotive convertion to DCC.<br> Thanks again&nbsp; guys :)<br> now can I use just one resistor on the common wire instead of one coming off each led ?<br> <br> E. T. Atkins wrote:<br>
<meta http-equiv="Content-Type" content="text/html;"> <title></title> ok my resistors are&nbsp; 470K not the right type :(<br> off to Radiddio shack I go. thanks for the help guys :)<br> <br> David French wrote:<br> <blockquote type="cite" cite="mid4537d7e2 snipped-for-privacy@mk-nntp-2.news.uk.tiscali.com"> <blockquote type="cite"> <blockquote type="cite"> <pre wrap="">I hooked the resistor up to long lead on the led. Is there a certain way the polarity of the resistor should be ? </pre> </blockquote> <pre wrap="">Resistors don't have polarity; LEDs do (they're diodes). If the LED is connected backwards, it won't light. Try it the other way (won't hurt it).
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E. T. Atkins wrote:

As long as only one of the LEDs will be turned on, yes!
Chuck D.
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You may. However there are some restrictions. First is that the resistor can't supply more current than what one LED can take so as a result, the resistor value doesn't change from the one resistor, one LED situation. This may be good for you as you already have that value of resistor. Second is that the brightness of the LEDs turned on will be less than just having one on. There is no destructive part of this but just rather that the LEDs will both (considering that there are two LEDs on) use some of the current coming through the resistor. Third, you may just make a mess by miswiring by trying this. The KISS principle works best here, especially since your knowledge of electronics and so forth isn't the best. -- Yeppie, Bush is such an idiot that He usually outwits everybody else. How dumb!
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Bob May wrote:

I always use a separate resistor for each LED. If you run two LED's off one resistor one LED will hog most of the current, leaving the other LED dim. Sometimes when the LEDS just happen to match well, they will share the current evenly, but this is not a common occurance. If you give each LED its own current limiting resistor they will always work. When you put two (or more) LEDS on a single resistor sometimes it works and sometimes it doesn't.
David Starr
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thanks again guys
David Starr wrote:

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470 Ohms is just about perfect at your stated voltage. If the LED doesn't light, I suspect you have it in backwards like others have suggested...flip it around.
Scott
E. T. Atkins wrote:

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"E. T. Atkins" skriver:

DCC normally gives up to 16 volt on a lamp output.
When I hook up LEDs I normally use 1Kohm resistors. There is no need for full power unless you want to use them as a torch.
Be aware of the polarity of the LED and make sure that the lamp output is on...
Klaus
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Klaus D. Mikkelsen wrote:

Here is a handy calculator for finding LED resistance values:
http://led.linear1.org/1led.wiz
Radio Shack also publishes a great little book titled: "Getting Started in Electronics" which will help you immensely in understanding things like resistors, diodes, and polarity. It worked for me.
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"video guy - www.locoworks.com" skriver:

Actually it is lacking important information..
When you use LED's it is often not neccesary to use it at full current consumption. My experiance shows that reducing from 20 to 10mA doesn't half the amount of light from the LED. It stays allmost the same.
Most moderne LED's give sufficent light from 5mA, eveten though it can consume 20mA.
Klaus
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There is a great joke to be had in this thread:
Question: How many r.m.r. "electronics experts" does it take to enlighten an electronic newbie about how to hook up an LED (and bias it correctly)?
Answer: to be determined as the answers keep coming in at a furious pace.
:-) I'm quite amused by all the responses and by the amount of information (correct and not-so-correct).
Gotta love r.m.r.
Peteski
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