Cree CXA analysis

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skyled

Member
MrFlux said:
How do you digitize the spectrum? What I do is to sample the curve with a couple of dozen points (with tops and bottoms) and then use cubic interpolation. Using just linear interpolation would not work well.
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Thank u for your answer
What I do is similar (I think) I measure the area under the curve every 5 nm, then I divide by the whole area
The difference may be due to my interpolation of the CIE curve

here are my results (It's in french but it's easy to translate)
I'll try to calculate these LER with your curve

tableau cree.jpg
tableau cree couleur.png
 
coolbreez1

coolbreez1

Well-Known Member
Awesome stuff guys, not only grate information, but suddenly all the calculus I am learning seems way more interesting! The viro 13 seems like the way to go, less spendy then the cree and much easier mounting and set up from the start. Seems like the lower voltage and 500mA current need should make finding power components a little easier/cheeper.

Now what we need to to combine this light output data with the area of illumation and optimal distance from the plant and figure out the most efficient placement when building larger arrays of the viro 13 arrays.

Does anyone have info on the optimal distance to have the viro's from the plant?
 
MrFlux

MrFlux

Well-Known Member
coolbreez1 said:
Awesome stuff guys, not only grate information, but suddenly all the calculus I am learning seems way more interesting! The viro 13 seems like the way to go, less spendy then the cree and much easier mounting and set up from the start. Seems like the lower voltage and 500mA current need should make finding power components a little easier/cheeper.
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I agree vero's are the way to go, just placed the order for them myself.

Does anyone have info on the optimal distance to have the viro's from the plant?
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That depends on how the vero's are distributed. One extreme is to place them all on a smallish heatsink with fan to create one superbright mini-sun. The other extreme is to space out the vero's evenly over a large area; the plants can then be much closer to the light. In calculus terms this would be the difference between a point source with inverse squared distance falloff, or a surface source with no falloff (for an infinite surface).
 
smokey the cat

smokey the cat

Well-Known Member
Heh, I received notice today that my Vero are on the way. Can't wait.


I'm really interested in supplemental lighting - will definitely try a run with nothing but Vero first, but I find it interesting that Rrog has been using halogen alongside his white XML panel. Now Vero is redder than XML, but it certainly wont be putting out all those red and far-red+ frequencies that Rrog is getting from a halogen.

I guess we'll get a better idea in the coming months what we need to add, if anything. Pico's results fill me with optimism at least.

In terms of supplementing - where do you think we go from Vero? The easiest possible option would be a string of red and far-red - say 10-20% of the rated output of the companion Vero emitters (to pluck an arbitrarily chosen number out of my arse). It seems a shame to spend as much on the supplemental emitters as the Vero, but Vero's price point is so very low to start with.


Anyone care to speculate?
 
Z

Zylev

New Member
0
View attachment 2872533
The Decor spectrum is the purple curve. As you can see a grow room is just not the right place for it. It almost looks like the regular 3000K with a filter on it. Btw this is for the Vero 10.

So how does the Vero compare to the Cree CXA? To make it a fair the comparison the results are scaled to 1 Watt input power:
View attachment 2872598
The solid lines are the Vero, the dashed lines the Cree. Take a look at the red curves of the warm whites. Which one would you prefer? This is all just math and graphs but I'm pretty sure everyone would pick the Vero. It has considerable more power in the red, and a bit less in the cyan. The blue region is about the same.
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So this is insanely awesome. I'm sold on the Vero! But can we get one last little graph on the Vero COB: the spectral photon flux per 1w?
 
MrFlux

MrFlux

Well-Known Member
smokey the cat said:
In terms of supplementing - where do you think we go from Vero? The easiest possible option would be a string of red and far-red - say 10-20% of the rated output of the companion Vero emitters (to pluck an arbitrarily chosen number out of my arse).
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If you add extra red to the already reddish combo of 3000K+3500K it would probably need some extra royal blue as well, otherwise, to put it in Picographs words, the plants won't know where the light is :smile:
 
smokey the cat

smokey the cat

Well-Known Member
MrFlux said:
If you add extra red to the already reddish combo of 3000K+3500K it would probably need some extra royal blue as well, otherwise, to put it in Picographs words, the plants won't know where the light is :smile:
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Maybe this means the best supplemental lighting is "more vero" - an intriguing thought.
 
Z

Zylev

New Member
PICOGRAV said:
What in the fuck? THATs your answer? Speak to people like you are a human being.
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I am past debating PAR ratings and their usefulness, I dont have to convince everyone I am right with words (I have very bad grammar I know) I would rather show you.

Einstein I guess did get one thing right, all this stuff is "Relative", you just need to expand your mind a little.
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Pictograv some people just can't handle their smoke
 
Z

Zylev

New Member
MrFlux said:
Thanks for the compliment and the rep, glad you like it.

Abiqua, the images should be fixed now. The algorithm is basically an inverse lumens calculation. It uses the CIE luminosity function and the relative power spectrum to first calculate the luminous efficacy of radiation (LER). The LER is purely a property of the spectrum. From the LER together with the efficacy, the radiometric efficiency (= efficacy/LER) is found. From that, with the relative spectra, the absolute spectra can be reconstructed.

For the PAR calculations the McCree1972 relative quantum efficiency data is used.

The CXA3590 looks identical to the CXA1304, only 24 times bigger... So to get the flux etc you can just multiply the above results by 24. Btw if there is interest to analyze other LED families: I do take requests.
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Ill take you up on that. We've seen plenty of stuff on Cree and Bridgelux... everything between 450 and 630nm... how about the photon flux of commonly-used emitters outside of that range? Rebel ES 670nm Deep Red, and MS SemiLED 410nm (Indigo/Violet)?
 
Z

Zylev

New Member
And also XP-E blue... another low-efficiency light that people often incorporate into their builds. I'd like to see the REAL number of photons being emitted off of this and the 680nm ES... and I'd like to see numbers on the SemiLED just because I plan to test it's frosting capabilities
 
SupraSPL

SupraSPL

Well-Known Member
Luckily it is much easier to compare the deep blues. The XPE2 royal blue top bin (p01) is 43% efficient (@ 700mA 50c) Comparing that against the XTE @ 50% and the Luxeon ES @ 55% under the same conditions.

The XPE2 blue suffers a much worse current droop at 700mA. I calculate 32 LM/W (700mA 50c). Mr Flux do you have an LER for ~475nm curve? Based on the current droop data I suggest that the XPE2 blue should be run at 350-500mA which kinda throws a monkey wrench in a lamp design. The same applies to the Luxeon ES colors except royal blue and deep red.

It is "silly" for manufacturers to give us only lumens on anything other than white LEDs. A slight shift in wavelength makes a huge difference in the LER so the lumens rating can be misleading.
 
SupraSPL

SupraSPL

Well-Known Member
According to this data, the SemiLEDs 410-420nm top bin is 25% efficient @ 700mA. The datasheet was incomplete so I was unable to adjust for junction temp but you get the idea. This is another example of an LED that suffers from current droop. It is probably better off at 350mA where it is 31.6% efficient.
 
MrFlux

MrFlux

Well-Known Member
SupraSPL said:
Mr Flux do you have an LER for ~475nm curve?
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Code: 
XP-E2 Blue
Power in        : 1.09 W
Luminous flux   : 45.7 lumen
Efficacy        : 42 lumen/W
LER             : 91 lumen/W
Radiometric eff.: 45.9%
Radiant flux    : 0.50 W
Photon flux     : 1.96 umol/s
Blue            : 84% power, 84% flux
Red             : 0% power, 0% flux
It is "silly" for manufacturers to give us only lumens on anything other than white LEDs. A slight shift in wavelength makes a huge difference in the LER so the lumens rating can be misleading.
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Preaching to the choir!
 
Z

Zylev

New Member
SupraSPL said:
According to this data, the SemiLEDs 410-420nm top bin is 25% efficient @ 700mA. The datasheet was incomplete so I was unable to adjust for junction temp but you get the idea. This is another example of an LED that suffers from current droop. It is probably better off at 350mA where it is 31.6% efficient.
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yes this LED is running very hard at 700mA current. I would expect a shortened lifespan, especially if my junction temps were over 50 deg C. but can't one drop the current in half by running them in series parallel?
 
P

pepperdust

Well-Known Member
MrFlux said:
That depends on how the vero's are distributed. One extreme is to place them all on a smallish heatsink with fan to create one superbright mini-sun. The other extreme is to space out the vero's evenly over a large area; the plants can then be much closer to the light. In calculus terms this would be the difference between a point source with inverse squared distance falloff, or a surface source with no falloff (for an infinite surface).
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here where led's get interesting.. which I think we wil always have a problem talking over 4-6 watts in a chip.

remember a led is not like a reflector. a reflector makes the light a lot more evenly spread, where the led, we don't use a reflector, or like a HPS reflector, as there is only one side to the led.. it's good as no reflector to deal with, light bouncing back and forth, where the led is like a mini reflector in-itself, but the bad is the higher watt you go the more un-even the light layout becomes, being +1 to a hps reflector, even though is not efficient, it still works to spread the light out more evenly then led. led though you can spread them out, but who wants to buy 70 chips and the cost of each chip, and wire each chip... so what have we come up with, cobbs. well good is there a shit load of light in the chip, bad is what I mentioned, you can never compete to have the spread of light like a hps reflector..

- I would never.. well right now given the lumens per watt, use a super build, like the first mentioned. what does it do? it nukes the middle, leaving shit for the edges. how do you avoid that? you pull it up losing much light, getting some more to the edges, but hurting output in the end.

-spread them out.. well that's fine, but who want's 10-40 watts blasting a plant, while once again, the center is lit huge, while the side light suffers again. bring it in close and whatever is under the led is getting nuked while the rest of the canopy suffers from low light.. raise it up, and once again lose light to raising the panel.


the main goal of LED, spread it out like a blanket covering the whole grow.. I would assume this problem will be dealt with by using the high watt cobbs, and raising the light just to the point where top leaf is not harmed.. my assumption would be the ideal light using 6 watts chips and about 50-70 chips spread as evenly as possible, keeping plant max of 2 foot height.
 
coolbreez1

coolbreez1

Well-Known Member
I think there are several different models to deal with, assuming you are dealing with white spectrum high output arrays there are two solutions.

First simple solution: Figure out the deal spacing of the lights to produce optimum coverage at the desired distance from the plant on a flat plane aka large heat sink.

The complex but over all more efficient grow more 3 dimensional and conduct the same calculation, but in relationship to a dome or half sphere for mounting, a cannabis light grow cap? However, due to the general spread of the led 110-120 degrees, this would give you fewer lights in relationship to the amount of plant that could be evenly exposed to light, on an individually light plant bases . Say 6 lights per plant or so, 3 in a triangular pattern on directly above the plant and 3 placed farther out and mounted on individual heat sinks attached to flexible metal tubing. A large light squid!
 
A

anomuumi

Member
Amazing thread, thanks for all the contributors, especially MrFlux! Am I totally wrong, but looking swiftly through the datasheets the bigger versions of CXA like 3050 seem to be more efficient? Underdriving for example a 5000k 70CRI 3050 with 700mA looks pretty f''n efficient for the $$. 170+lm/W at 25c or am I hallucinating?

Thinking that these COB's are what consumer and industrial light manufacturers will be using mostly, I can only wonder what kind of development we'll see in near future. Awesome!
 
MrFlux

MrFlux

Well-Known Member
anomuumi said:
Amazing thread, thanks for all the contributors, especially MrFlux! Am I totally wrong, but looking swiftly through the datasheets the bigger versions of CXA like 3050 seem to be more efficient? Underdriving for example a 5000k 70CRI 3050 with 700mA looks pretty f''n efficient for the $$. 170+lm/W at 25c or am I hallucinating?
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Hi muumi, glad you like the thread. I haven't noticed any efficiency differences across the various CXA sizes. From the specs I looked at it was always around 139 lm/W at test current. Haven't looked through all the individual specs though. At half the test current it would indeed be about 170 lm/W, you are not hallucinating there :-). This puts it right up there with the XML2 at a fraction of the cost.
 
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