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Resident NICO Mod
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Discussion Starter #1
I have bought 2 seperate sets of white 194 LED's in the past month. The most recent set I got is white but it has a hint of blue in it. My older set which I installed in my corners and parking lamps look very blue but they are the white ones!!!. Is my eyesight ****ed up or are they supposed to be like that?
 

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Infantry leads the way!
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2,061 Posts
Rev put down the bottle and then look at them and see what colro they are :)
 

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Non-Newbie
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476 Posts
Yeah, I ordered a set of white LEDS off of (www.autodynamic.com)
I put one white LED in the corner of one side and one blue/white EUROLITE bulb in the opposite side.
I'll tell you that the intensity of the blue in the white LED overpowered the other by FAR.
I'm curious if there is a white LED made that actually has a WHITE look to it.
 

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Kill me now!
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288 Posts
It's because they can't really make white LEDs. It is really something like a blue LED but the light shines through a little filter to make it appear white. That is also why white LEDs also put out lower lumens, the filter cuts out some of the light. Some are more white than others though.
 

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Nipponese
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5,458 Posts
OptimusKryme said:
It's because they can't really make white LEDs. It is really something like a blue LED but the light shines through a little filter to make it appear white. That is also why white LEDs also put out lower lumens, the filter cuts out some of the light. Some are more white than others though.
You've got it the other way around, a blue LED is far more difficult (and expensive) to make brighter. Also, they do not use any kind of "filter" on LEDs, it is purely a characteristic of each diode they use that differs in color. Think about it, you cannot filter a blue light (470nm wavelength) to get white light (all wavelangths). Your theory is also flawed since the way you explain it, white LEDs should be more difficult to manufacture thus being more expensive but in reality, blue LEDs are the most expensive in the industry.
 

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Kill me now!
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288 Posts
No...white LED's are the most expensive from what I've heard. They do filter blue light through a phosphorescent material.

From EEtimes:

"By adding a little more indium, a blue LED can be turned into a green LED. Nakamura said he placed a novel phosphor over his blue chip to get a white light."

From Optics.org:

"white LEDs, which are made by combining a blue LED chip with a yellow phosphor"

From NSS:
"The technology used in the white LED starts with a blue LED combined with some very special phosphorescent materials."
"
 

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Nipponese
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5,458 Posts
Fine, go look for yourself at the stores, see what you find. You can report back to me with your findings. Also, "combining yellow phosphor" is not "filtering". What the yellow phosphor does is it emits yellow wavelengths to the incoming blue light making it appear white to the human eye. Like I said before, you cannot filter a single wavelength light to achieve full spectrum light (white light), doing the opposite is possible though. You can filter out certain wavelengths FROM a full spectrum light to achieve a narrow wavelength (like blue), or ADD a wavelength to achieve some other color.
 

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New Transaxle JBWelded!
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you guys are both basically saying the same thing.

the blue LED, which is much more expensive to make, was the key building block in making white LED's. They first made them by putting a blue, green, and red led on the same substrate, then adjusting the voltage between them to match the emitted intensities. I'm not sure if you can still get the multi-lead led's that you can adjust yourself to make any color, but they were pretty cool.

and, poison is correct, it's not a passive filter, it absorbs some of the energy and emits at a different bandgap, or a different color. it's an active filter. This is how they started making white led's cheaper than just assembling 3 different LED's at a time.
 
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