FWIW: Yuji and rngwn 5mm LEDs, observations and comments

Flashlight Modding and DIY Parts
1

Unfortunately I’m missing all the tools for quantitative analysis, but I’ll show spectra, beams, and fluorescence to UV light (390nm).

From top to bottom / left to right:

Sofirn C01, black, early sample with resign not cured
Sofirn C01, red
Yuji in Tube, source: LEDSales
rngwn 3200K in Tube, normal
rngwn 3200K in Tube, high power

Observation: The black and red C01 show a unique caramel tint, much less pronounced in the red sample, but still there. Absent in my recently bought Yujis from LEDSales, normal rosy tint. rngwns normal 3200K LEDs appear a little yellowish in contrast, but has a very nice tint when seen isolated. The new high power 3200K rngwn offers is much closer to the Yujis.

The fluorescence of the Yujis is blue/green, which is unusual for warm white LEDs. It is better seen in the reflection.


From top to bottom / left to right:

Sofirn C01, black, early sample with resign not cured
Sofirn C01, red
Yuji in Tube, source: LEDSales
rngwn 3200K in Tube, normal
rngwn 3200K in Tube, high power

My conclusion: The high power 3200K from rngwn are thus far the best approximation to the Yujis that Sofirn used in their C01. Yujis from the LEDSales stock have similar spectra (image is uncalibrated), but look much different.

Can anybody explain the fluorescence? Not shown here, but the cw Yuji has a red fluorescence. How do those LEDs work?

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Thanks! I always like seeing color data - spectra or CRI and related scores.

I agree these are excellent emitters for all sorts of tinkering. I’ve even started hanging onto some of the more interesting among the cheap 3xAAA lights that I encounter, as they are far more appealing in high CRI than in supercool white.

Interesting that rngwn’s emitter’s seem (or perhaps it relates to the uncalibrated spectrometer?) to have a slightly different pump wavelength than the Yuji’s - closer to 470nm on average rather than 450nm. Meanwhile, the red portion of their spectra seems have it’s falloff occur a similar distance later.

I don’t know specific reason why the 5600K Yuji fluoresces in red, but a 5600K will have a different phosphor mix than a 3200K, so I’m not surprised there is a difference under UV light.

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How did you measure it? How much confidence do you have in these measurements?

Have you tried measuring it multiple times?

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Gentlemen, as I said, it is all uncalibrated. This was done with a piece of broken DVD on the webcam.

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Yep, but usually I see red fluorescence from warm tints and green from cold tints. The Yujis are the only exception I have seen thus far. Makes me wonder.

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Thanks for sharing info and a new source for Yujis!

> Observation: The black and red C01 show a unique caramel tint, much less pronounced in the red sample, but still there. Absent in my recently bought Yujis from LEDSales, normal rosy tint.

please clarify, is the Yuji from LED sales rosy or caramel?

> My conclusion: The high power 3200K from rngwn are thus far the best approximation to the Yujis that Sofirn used in their C01. Yujis from the LEDSales stock have similar spectra (image is uncalibrated), but look much different.

please clarify
I cannot follow the unlabeled photos

which is the sofirn yuji?
which is the LEDSales yuji?

> The Yujis are the only exception I have seen thus far.

me too… I Love my 5600k Yuji, even though it fluoresces backwards to cree… :slight_smile:

yuji:

cree:

7

The order is specified in the OP. Three Yujis, two nrgwn. Top to bottom, left to right.

The LEDs I bought aren’t caramel. The Sofirn Yujis are of varying quality.