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Which LED do I need.

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bearman:
One hint when buying LEDs.   Make sure you get LEDs with at least 100 MCD brightness rating.   My experieince has taught me if you buy these huge bargain LED deals you get a lot of LEDs but they are not very visible in farely brightly lit environments.  They are usually under 10 MCD light output.   It sucks when you have to get right on top of an LED indicator to tell if it is really on or not or it looks like its on but it is ambient light shining through it.   Most of these bulk deals don't even list MCD brightness output.  Stay away from those or ask if they know what the light output is.  I have seen adds describing "super bright LEDs"  then I look them up if mfg. part# is provided and they are 5 MCD.  A super bright LED to me is like 5000 to 15,000MCD.   100 MCD or higher is a good indicator light level.   

Oh!  I use diffused LEDs for any logic output and indicator lights .  I use clear lens LEDs for displays and lighting effects.

The other thing is this.  If the LED is too bright at 20ma. current level for your app you can always increase the resistance and lower the current running through it to lower the light intensity to meet your needs.  If your LED is too dim too start with you can only increase the current so much before they die or have a short life span.

I learned the hard way.  In fact just the other I built a simple 20ma current source for testing all the LEDs I collected over 25 years.  I threw away tons because they were just garbage and I would not use them for any real applications as they are too dim or not evenly lit and not very visible when on.

Hope I saved you some grief and coinage.

Bearman

Zero999:
Also, don't neglect the viewing angle, you can get a narrow beam LED which is very bright but will appear dim if viewed from the wrong angle.

Joshua:

--- Quote from: bearman on August 22, 2010, 09:26:44 pm ---One hint when buying LEDs.   Make sure you get LEDs with at least 100 MCD brightness rating.

--- End quote ---

Thanks for the great info! I've never heard of such a thing as MCD. I was actually planning on possibly buying such a bulk (discount) pack, but I think i'll just go straight for buying just quite a few of a specific kind.


--- Quote from: Hero999 on August 29, 2010, 09:29:23 am ---Also, don't neglect the viewing angle, you can get a narrow beam LED which is very bright but will appear dim if viewed from the wrong angle.

--- End quote ---

Thanks, I would have never thought of that.



Thanks again everybody,
Pianokid1994

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