stardustsailor
Well-Known Member
Very 'enlightening ' about reds .... :
http://www.life.illinois.edu/govindjee/photosynBook/Chapter13.pdf
http://www.life.illinois.edu/govindjee/photosynBook/Chapter13.pdf
Summer 2014 Led Growing Notes...
- Thread starter stardustsailor
- Start date
stardustsailor
Well-Known Member
Cyan 505 nm :
" Supplemental 505 nm light had the most pronounced
effect on the photosynthetic pigment contents in lettuce:
the concentrations of chlorophyll a, chlorophyll b and
carotenoids was determined to be ~1.2 times higher as
compared to lettuce, grown without supplemental LED
irradiance. The addition of green light may improve
plant growth and photosynthesis by perceived specific
photoreceptors and induces the pattern of investment
of captured resources and the ability of the plant to
capture further resources (Kim et al., 2006). However,
supplemental green 535 nm light had no significant effect
on chlorophylls. Only on the contents of carotenoid*
pigments significant effects were found. "
" The 505 nm light, being intermediate
between blue and green wavelengths, had the most
pronounced effect on photosynthetic pigment contents,
higher NAR value. "
*Carotenoids amongst other 'protect' from prolonged exposure at high irradiances .
Another reason why the green wls are needed at high irradiances ...
http://www.zemdirbyste-agriculture.lt/wp-content/uploads/2014/03/101_1_str10.pdf
" Supplemental 505 nm light had the most pronounced
effect on the photosynthetic pigment contents in lettuce:
the concentrations of chlorophyll a, chlorophyll b and
carotenoids was determined to be ~1.2 times higher as
compared to lettuce, grown without supplemental LED
irradiance. The addition of green light may improve
plant growth and photosynthesis by perceived specific
photoreceptors and induces the pattern of investment
of captured resources and the ability of the plant to
capture further resources (Kim et al., 2006). However,
supplemental green 535 nm light had no significant effect
on chlorophylls. Only on the contents of carotenoid*
pigments significant effects were found. "
" The 505 nm light, being intermediate
between blue and green wavelengths, had the most
pronounced effect on photosynthetic pigment contents,
higher NAR value. "
*Carotenoids amongst other 'protect' from prolonged exposure at high irradiances .
Another reason why the green wls are needed at high irradiances ...
http://www.zemdirbyste-agriculture.lt/wp-content/uploads/2014/03/101_1_str10.pdf
stardustsailor
Well-Known Member
Economic Analysis of Greenhouse Lighting: Light Emitting Diodes vs. High Intensity Discharge Fixtures
Abstract
Lighting technologies for plant growth are improving rapidly, providing numerous options for supplemental lighting in greenhouses. Here we report the photosynthetic (400–700 nm) photon efficiency and photon distribution pattern of two double-ended HPS fixtures, five mogul-base HPS fixtures, ten LED fixtures, three ceramic metal halide fixtures, and two fluorescent fixtures. The two most efficient LED and the two most efficient double-ended HPS fixtures had nearly identical efficiencies at 1.66 to 1.70 micromoles per joule. These four fixtures represent a dramatic improvement over the 1.02 micromoles per joule efficiency of the mogul-base HPS fixtures that are in common use. The best ceramic metal halide and fluorescent fixtures had efficiencies of 1.46 and 0.95 micromoles per joule, respectively. We also calculated the initial capital cost of fixtures per photon delivered and determined that LED fixtures cost five to ten times more than HPS fixtures. The five-year electric plus fixture cost per mole of photons is thus 2.3 times higher for LED fixtures, due to high capital costs. Compared to electric costs, our analysis indicates that the long-term maintenance costs are small for both technologies. If widely spaced benches are a necessary part of a production system, the unique ability of LED fixtures to efficiently focus photons on specific areas can be used to improve the photon capture by plant canopies. Our analysis demonstrates, however, that the cost per photon delivered is higher in these systems, regardless of fixture category. The lowest lighting system costs are realized when an efficient fixture is coupled with effective canopy photon capture.
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099010
Abstract
Lighting technologies for plant growth are improving rapidly, providing numerous options for supplemental lighting in greenhouses. Here we report the photosynthetic (400–700 nm) photon efficiency and photon distribution pattern of two double-ended HPS fixtures, five mogul-base HPS fixtures, ten LED fixtures, three ceramic metal halide fixtures, and two fluorescent fixtures. The two most efficient LED and the two most efficient double-ended HPS fixtures had nearly identical efficiencies at 1.66 to 1.70 micromoles per joule. These four fixtures represent a dramatic improvement over the 1.02 micromoles per joule efficiency of the mogul-base HPS fixtures that are in common use. The best ceramic metal halide and fluorescent fixtures had efficiencies of 1.46 and 0.95 micromoles per joule, respectively. We also calculated the initial capital cost of fixtures per photon delivered and determined that LED fixtures cost five to ten times more than HPS fixtures. The five-year electric plus fixture cost per mole of photons is thus 2.3 times higher for LED fixtures, due to high capital costs. Compared to electric costs, our analysis indicates that the long-term maintenance costs are small for both technologies. If widely spaced benches are a necessary part of a production system, the unique ability of LED fixtures to efficiently focus photons on specific areas can be used to improve the photon capture by plant canopies. Our analysis demonstrates, however, that the cost per photon delivered is higher in these systems, regardless of fixture category. The lowest lighting system costs are realized when an efficient fixture is coupled with effective canopy photon capture.
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0099010
stardustsailor
Well-Known Member
From the link above :
A note further ....
Once more one can have a monochromatic leds based led grow light fixture ...
And while Red and blue are the most efficient leds in generating & delivering light quanta ....
While for Amber ,Green and Far red leds needed to make the fixture " operational " at high irradiances ,
things are not so great ,efficiency wise ...
But not so many of them needed ,anyway ..
So overall efficiency should be somewhat between red 655 nm and cool whites ....
( Stoner's hard guess .!! )
PC warm whites ,'stand ' at the 'middle' ...
Ehm..Not so bad ....
They have plenty of other 'pros' ,anyway ...
....
Cheers .
A note further ....
Once more one can have a monochromatic leds based led grow light fixture ...
And while Red and blue are the most efficient leds in generating & delivering light quanta ....
While for Amber ,Green and Far red leds needed to make the fixture " operational " at high irradiances ,
things are not so great ,efficiency wise ...
But not so many of them needed ,anyway ..
So overall efficiency should be somewhat between red 655 nm and cool whites ....
( Stoner's hard guess .!! )
PC warm whites ,'stand ' at the 'middle' ...
Ehm..Not so bad ....
They have plenty of other 'pros' ,anyway ...
....Cheers .
epicfail
Well-Known Member
Supra, it seems odd to me that the 10mm stars are $2.77usd and the loose ones are $4.18usd, are they the same chip? also where do you see the group listed on mouser and digi-key? sorry if its obvious.
Scotch, Did you order from mouser (P5 670nm)? those have to be reflowed on to a sinkpad like Pos linked correct? that would increase the cost by $2.45usd per led.
It seems like the best deal for me would be to get the 665nm 10mm ($2.77) or 20mm ($3.34) stars, 10's might be too small to work with. The shipping isn't to different when you take into account that I would not need sinkpads or do any reflow soldering. I am going to contact them about the chips used. I knew if I waited long enough Cree would make a 660+/-, it took less time then I thought.
Scotch089
Well-Known Member
Well... That's doesnt fuckin suck. *palm-to-face*
Positivity
Well-Known Member
I haven't checked the fit or anything yet. Pretty sure the xp series covers xpg and xpe...same footprint.
I'm only using the sinkpad since my drivers are 1a...otherwise the one epic found looks good.
Copper sinkpad ain't a bad idea though if you don't mind the extra work. Would run hella cool at 700ma..
Everything's in this thread...https://www.rollitup.org/t/how-to-reflow-leds-onto-star.820160/
The cree stencil is easier to upload into oshstencils than the oslon. Oslon needs to be opened and extracted from a file first. Just download the cree gerber into oshstencils...I'd order the jig to go with it...nothing fancy just agree to all options from what I remember.
Here it is....https://oshpark.com/shared_projects/dw8NYoED
I'm only using the sinkpad since my drivers are 1a...otherwise the one epic found looks good.
Copper sinkpad ain't a bad idea though if you don't mind the extra work. Would run hella cool at 700ma..
Everything's in this thread...https://www.rollitup.org/t/how-to-reflow-leds-onto-star.820160/
The cree stencil is easier to upload into oshstencils than the oslon. Oslon needs to be opened and extracted from a file first. Just download the cree gerber into oshstencils...I'd order the jig to go with it...nothing fancy just agree to all options from what I remember.
Here it is....https://oshpark.com/shared_projects/dw8NYoED
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SupraSPL
Well-Known Member
Scotch check these out, XPG/XPE/XTE stars $0.14 ea.
http://www.ebay.com/itm/321374164114
You would be amazed how easy reflow can be. There is the right way to do it (stencil, solder paste, oven with temp control and ramp up ramp down times) and there is the good enough way if you are just doing a handful.
Hold the star with needle nose or scissors. Put a bit of flux gel on the pad and with your clean iron apply a thin layer of 63/57 lead solder (Cree recommended). Then heat the star from the side (with your iron) until the solder remelts and the XPE seats itself. If you prefer, you can push down gently on the XPE as it cools and any excess solder it will pop out the sides as little beads so you get extremely thin layer of solder.
I don't bother much with ramp up temp but I do make an effort not to let it cool down too fast by dropping the hot stars onto a wooded surface. Easy process and no worries
http://www.ebay.com/itm/321374164114
You would be amazed how easy reflow can be. There is the right way to do it (stencil, solder paste, oven with temp control and ramp up ramp down times) and there is the good enough way if you are just doing a handful.
Hold the star with needle nose or scissors. Put a bit of flux gel on the pad and with your clean iron apply a thin layer of 63/57 lead solder (Cree recommended). Then heat the star from the side (with your iron) until the solder remelts and the XPE seats itself. If you prefer, you can push down gently on the XPE as it cools and any excess solder it will pop out the sides as little beads so you get extremely thin layer of solder.
I don't bother much with ramp up temp but I do make an effort not to let it cool down too fast by dropping the hot stars onto a wooded surface. Easy process and no worries
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SupraSPL
Well-Known Member
From this study, copper may be worthwhile when you run hard, but if you run soft there is very little difference in junction temp between copper and aluminum. So you would be better off spending the $ on running soft rather than on copper pads
Attachments
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SupraSPL
Well-Known Member
One good thing I have noticed about copper stars, they don't need much work to become flat. I ordered that 50 pack of aluminum XP/XT stars and flattebed the whole bunch while they were still connected, much faster and easier than doing them individually.
This difference between copper and aluminum in the graphs above might be even less if they were both flattened and a very high quality thermal paste was used.
This difference between copper and aluminum in the graphs above might be even less if they were both flattened and a very high quality thermal paste was used.
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Scotch089
Well-Known Member
So I ordered some 660-665s from cutter before getting some of the 665-670s from a local on here, I cancelled after finding out they did not have any in stock and got myomey back....
....and I just got a dhl package with 9 of the 660s in the mail. Heh. Free of charge (including the crazy shipping)
....and I just got a dhl package with 9 of the 660s in the mail. Heh. Free of charge (including the crazy shipping)