Tint Shift vs. Current vs. Bin

Bob_G

Enlightened
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Apr 25, 2005
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Kentucky, USA
I'm wondering if there is at least a semi-definitive answer to this, or is it one of the imponderables?

Is the tint shift when say, underdriving a LuxIII predictable? Is it always in the same direction, or does it depend on the tint bin - for instance maybe a X1 goes toward green and a YO goes toward blue?

What current qualifies as underdriving in terms of tint shift?

Is shift more likely when underdriving than over?

If both, does it shift in the same direction?

Just intellectual curiosity here, nothing pressing /ubbthreads/images/graemlins/smile.gif
 

Chop

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Jul 22, 2003
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Louisiana
What I have noticed regarding tint shift is that luxeons will tend to show their true binning when underdriven and tend to get whiter when you drive them hard.

I must say that I'm not a luxeon expert, nor am I well schooled in electronics; however, I have had a fair number of luxeons come across my work bench.

Driving a luxeon in an underdriven state occurs whenever you drive a luxeon at a current level that is less than that which is specified for that luxeon. For a 1W that would be less than 350mA, and for a Lux III, that would be 700mA. The more you underdrive the more pronounced the tint shift.

What I have noticed is the following when underdriving luxeons, and when I say underdriving, I mean driving them to about 200mA or less. The following also applies only to Lux III emitters. I don't bother to stock 1W luxeons. As I said above, they all tend to get whiter as you drive them hard, over an amp.

The following is also in general terms. I have seen deviations from what follows:

With the TWOJs, I've seen them range from staying white to going to the yellow side (a few have even gone greenish).

With TX1Js I've seen them range from staying white/slightly yellow to down right green.

With TYOJs I've seen them range from slightly blue/white to very blue.

TYAJ have just varied in the tint of blue.

TXOJs have varied from slightly blue to a bit more than slightly blue. I belive that the XO color bin is the "safest" color bin going. I've (in my limited experience) never seen one of these give off an offensive color.

I haven't had enough experience with any other bins to really make a generalized comment.
 

sunspot

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Aug 22, 2001
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Graham, NC
Thank you Tony. I'm book marking this page. I never could figure out that darned bin code color chart. I just bought a TYAH and a TYOJ and praying for no green tint.
 

wasBlinded

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Dec 14, 2004
Messages
1,222
Location
Oklahoma
The usual shift at lower drive currents is in the direction of the X1/V1 bin from what I have seen and data posted here. So a WO bin might go greenish, but a more violet bin like the YA might actually become "whiter", which has been my experience. I also have an XO bin light that goes a little bit green at very low drive currents - but not objectionably so.

I've seen a few Luxeons that did not seem to shift tint at all, but the Mark I eyeball can be easily fooled.

If you really hate any green, start with a YA or WA bin to be safe.
 
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