# Best "Selective Yellow" LED or thereabouts?



## Hypersapien (Apr 19, 2011)

Hi all,

I am looking at placing an order at DX for some toys to try to build up some simple fog lights and or something to use for an optional mode for an off-road helmet light.

I have done some searches but I don't find anything putting out light in a pure yellow or selective yellow range that is also a very high power source along the lines of a Cree XR-E or similar.

I know a bit from reading about the way LEDs operate that the strongest light you will be able to produce in output will necessarily be more blue than anything but is there an option to look at regarding a selective yellow hue?

I have come across some Amber lights by Cree that look like they might be close but I don't find anything like what I want, namely the classic Rally yellow...

Any part numbers that you may suggest especially DX SKU's would be appreciated.

Or maybe I am searching for no reason... will dying/painting the optic be a better choice?

Cheers!


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## Neondiod (Apr 20, 2011)

I've vever seen a selective yellow power led. But they are not too uncommon as 5 mm leds, by the name "golden white". Not at DX thou.


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## MichaelW (Apr 21, 2011)

I would imagine that the phosphor of the Rebel PC Amber could be modified to make selective yellow. [I am still waiting...]

A 'small scale' yellow fog light
http://www.lumaray.com/fog_preview_800.html


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## Hypersapien (Apr 21, 2011)

That is a cool link Michael!

The site looks to be far out of date... Almost a year since last updated. Do you know anything more about ordering those units?

I imagine that would work perfectly for my application... Unfortunately no specs to go along with the eye candy.

Anyone else have a suggestion?... I didn't have much luck googling for Golden White LEDs other than some lame model railroader commentaries...


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## MichaelW (Apr 21, 2011)

No, you could throw out an email and see if they are still around and kicking.
I remember Surefire used to offer yellow & yellow-green secondary LED colors, so there should still be a source of decent flux 5mm LEDs

http://www.candlepowerforums.com/vb...s-sugestions&p=2283806&viewfull=1#post2283806


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## Anders Hoveland (Jan 23, 2015)

Hypersapien said:


> I have done some searches but I don't find anything putting out light in a pure yellow that is also a very high power source along the lines of a Cree XR-E or similar.


570-580nm is a difficult color to be made efficiently by an LED emitter at this time, so you will probably not find any, except very low power 5mm ones for indicator use. 


In terms of reputable companies which manufacture high quality LEDs, that is more difficult. Several companies manufacture phosphor-converted greenish-yellow and amber-colored LEDs. These are basically similar to white LEDs except they use a phosphor that emits a more specific color. Of these, the only one which has a true yellow color is the Osram Signal Series LCY CLBP ceramic yellow. This does not appear to be currently available for distribution to North America (at least not in small quantities), and Mouser lists it as non-stocked.

There's some yellow LEDs being sold on Alibaba. have you seen this?
http://www.alibaba.com/product-detail/China-Manufacturer-1W-575nm-585nm-Yello_60044102374.html

There are all sorts of cheap chinese-sourced phosphor-converted yellow LEDs being sold on ebay, but I would recommend some caution because chinese sellers are not always entirely honest, and there is a language barrier, so many of the LEDs being marketed as "yellow" actually give off more of an amber color of light. One thing I have learned though, if they show a picture of the actual LED, the appearance of the phosphor is always somewhat more red colored than the actual color of light the LED emits. For example, phosphor that emits green light looks yellowish-green when the LED is off. Phosphor that appears to be an orange color emits a more yellowish color of light. Phosphor that looks yellow actually emits a more greenish-yellow color of light.

I have no doubt that some of these Chinese sellers actually sell LEDs that give off a true yellow color of light, but you might have to find out through a lot of trial and error. And just make sure the specific type of LED you are ordering is covered with phosphor, because if not I can guarantee you it will be 585-590nm amber color.


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## Anders Hoveland (Mar 10, 2015)

I have obtained the Osram Signal Series LCY CLBP ceramic yellow for testing. Unfortunately the color of light it gives off is only the slightest degree more yellowish colored than a 590nm amber emitter.
Viewed through a diffraction grating, there is definitely plenty of true yellow wavelengths in the spectrum though, in fact it seems to be centered at true yellow (575nm), so maybe if a little filtering was used...
I think this LED would also give much better CRI if used in the place of a regular amber in a RGBA combination multiemitter white LED fixture (used for stage lighting). Just using red and amber emitters does not work so well for correctly rendering skin tones and yellow colors simultaneously, that is what I have found in my experiments.

One big advantage of phosphor-conversion is efficiency. The Signal LCY CLBP is much brighter than a regular amber emitter, more than twice as much.


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## alpg88 (Mar 10, 2015)

i wonder do we really need it now? 

the purpose of select yellow is "The intent of selective yellow is to improve vision by removing short, blue to violet wavelengths from the projected light. These wavelengths are difficult for the human visual system to process properly, and they cause perceived dazzle and glare effects in rain, fog and snow.[7]​"

nowadays we have leds that emmit light in very narrow range, with not as much blue and violet, as in old school inc. bulb. some people believe that yellow goes thru fog better, i'm not sure it is true,


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## Anders Hoveland (Mar 10, 2015)

alpg88 said:


> i wonder do we really need it now?


I know the only primary colors are red, green, and blue, and that yellow is essentially just a mix of red and green, but I really view the color yellow as a very important primary color. 

I can see orange as "yellowish-red", but I just cannot see yellow as anything other than yellow. It is a _real_ color to me. 
Amber colored LEDs just seem yellowish-orange (or reddish-yellow if you prefer). Perhaps this may all be very subjective, but I think it is very important to have an LED with a "true yellow" color.


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## alpg88 (Mar 10, 2015)

yea orange\amber is pretty much all we got as far as yellow led goes, you prbly can acheve what you want with rgb leds,.

Limit towards red






Limit towards green





Limit towards white





Limit towards spectral value






For front fog lamps, the limit towards white is extended:

Limit towards white














 Colour coordinatesHex triplet#FFBA00sRGB*B*​ (r, g, b)(255, 186, 0)CMYK*H*​ (c, m, y, k)(0, 27, 100, 0)HSV (h, s, v)(44°, 100%, 100%

what purpose do you want the true yellow led for?


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