Calling out to Weezard for LED advice

[thepaan]

I just finished putting together a grow light using four LedEngin's deep red and one blue. It works like a champ. I mounted them all on one U81C and stuck it in a desk lamp so I could move it around but it is much heavier than I thought so I needed to prop it up. I attached an extra 80mm computer fan to the heatsink but I don't think it needs it because it is cool to the touch right by the LEDs after running all day. I recently checked Mouser for more of the 15W 660nm reds but, it appears they are no longer in production. I want to get some kind of enclosure going maybe underneath a sofa table or something.... I guess I'll have to figure something out with the 10W.

[Weezard]

That is clever, and efficient!
Nice work, brah.

My 4:1 "cakepan" is my most versatile lamp.
Great vegger.
Very good budder too when ya back off the blue and snug it up a to the plants little.
Built 5 lesser lamps before it while dialing it in.
Looks like you did some serious study, then cut to the chase.
Impressive.:thumbsup:

Aloha

Weezard

[Dutch Pimp]

...http://boards.cannabis.com/introduce...ml#post2071160

[SupraSPL]

Hello fellas. I have been studying the LEDEngin PDFs trying to make some price and output comparisons. I couldn't find anywhere on the mouser site where the bin code is specified. When you buy them in small quantities do they specify the bin for you before you buy?

[Weezard]

Hello fellas. I have been studying the LEDEngin PDFs trying to make some price and output comparisons. I couldn't find anywhere on the mouser site where the bin code is specified. When you buy them in small quantities do they specify the bin for you before you buy?

Could not find bin codes either.
Even on the 5 Watt stars.
Even on Ledengin's website.
Though I must admit I didn't look very hard.

Did not expect them on the 15 Watt emitters anyway.
(It was a short run. Kinda all one bin.)

Though DH was unhappy with the workmanship on some 15W. Ledengins as I recall.
Mine were quite uniform.:jointsmile:

And, while I lack the funds and patience for precise measurements, I still manage to cheaply gauge the relative output of narrow band leds.
[attachment=o238717]
My li'l redneck radiometer gives me an cheap n dirty method of comparing relative strength.:rastasmoke:
I'm a practical type.
I worry little about bins, minor variations, meaningless details, etc.
I'm jus' a bottom line, kine.

I read, a lot, then experimented.
Tested the concepts that I'd read about.
Each light taught me something about a plants needs.
Then I simplified.
Eliminated everything they didn't actually need.

BTW, that little 5 Watt stars array, grew some serious bud with 660 nm.reds, and "royal" blue.
But,
The 15 Watt emitter arrays:asskick:!!

Any way we can he'p, no be shy, brah.

Aloha,
Weezard

[thepaan]

I was having problems with my plant after moving it inside from the roof this winter. First I thought it was too much water then the fertilizer. Turns out it was the light. 4 red and 1 blue 15W were burning the poor thing. I've got it under control now though. I went down to the store and bought one of those dome diffuse covers you can put on your hallway light and it went from yellow/brown to dark green in 2 days.

Just a tip for anyone having the same problem.

[thepaan]

So, I've been toiling over some math for the last few days and I think I have come up with something epic. From the top even though a lot is going to be repeat:

Photosynthetically active radiation (PAR) is the wavelength of light which plants respond to 400-700 nm. The daily light integral (DLI) measured in moles per square meter per day (mol/m2/d) says you need 22 or more to grow excellent crop plants. I couldn't find a listing for MJ but here is a chart (down on page 5) for a bunch of other plants. LEDs have light output measured in watts (W). 1 watt = 1 joule per second. I have calculated mol/J (and µmol/J) for every 10 nm between 400 and 700, inclusive and found the average. I then converted DLI (mol/m2/d) to µmol/m2/s for 12 hours of light and divided by the average µmol/J to get W/m2. Lastly, I multiplied by 60% which is the average efficiency of all wavelengths between 400 and 700 nm at driving photosynthesis (the idea being that deep red is 100% efficient).

This is the spreadsheet I came up with. It tells you how many red LEDs and from that you can figure out how many blue per square meter you should be using. What do you guys think?

[khyberkitsune]

So, I've been toiling over some math for the last few days and I think I have come up with something epic. From the top even though a lot is going to be repeat:

Photosynthetically active radiation (PAR) is the wavelength of light which plants respond to 400-700 nm. The daily light integral (DLI) measured in moles per square meter per day (mol/m2/d) says you need 22 or more to grow excellent crop plants. I couldn't find a listing for MJ but here is a chart (down on page 5) for a bunch of other plants. LEDs have light output measured in watts (W). 1 watt = 1 joule per second. I have calculated mol/J (and µmol/J) for every 10 nm between 400 and 700, inclusive and found the average. I then converted DLI (mol/m2/d) to µmol/m2/s for 12 hours of light and divided by the average µmol/J to get W/m2. Lastly, I multiplied by 60% which is the average efficiency of all wavelengths between 400 and 700 nm at driving photosynthesis (the idea being that deep red is 100% efficient).

This is the spreadsheet I came up with. It tells you how many red LEDs and from that you can figure out how many blue per square meter you should be using. What do you guys think?

I think that is a good approach and is great data - allow me to toss out another approach.

First, I kept in mind that plants pretty much adapted to their lighting environment. Light levels and spectral balance is somewhat important. Next, for the boundary between spring and summer, I checked with NASA records to check the insolation levels recorded at the edge of the atmosphere and at the edge of sea level - I noticed the balance, at least in terms of radiometric power, were almost even - blue was in the lead. Then I checked again for the beginning of September (bear all of this is for my old area, in Tennessee, I haven't checked to see if there has been any data for my area of Cali.) The ratio had changed , with red slightly in the lead. So I figured a 60:40 blue:red mix for vegetation, and a 60:40 red;blue mix for blooming. I might modify the panel once it arrives, see if I can't drop a dimmer on the blues so I can drop the blue down to help trigger flowering, and then bump it back up a little to provide some extra boost. I've always had poor yield results, especially with tomatoes and peppers, with those 7:1:1 panels. More blue is needed. Other lighting companies realized this and are starting to offer blue-dominant panels to supplement their lacking UFO panels. NASA realized their folly and some of the latest panel design I've seen from them is pretty much 1:2 blue:red (looks like 465 and 670nm.)

[thepaan]

I think that is a good approach and is great data - allow me to toss out another approach.

First, I kept in mind that plants pretty much adapted to their lighting environment. Light levels and spectral balance is somewhat important. Next, for the boundary between spring and summer, I checked with NASA records to check the insolation levels recorded at the edge of the atmosphere and at the edge of sea level - I noticed the balance, at least in terms of radiometric power, were almost even - blue was in the lead. Then I checked again for the beginning of September (bear all of this is for my old area, in Tennessee, I haven't checked to see if there has been any data for my area of Cali.) The ratio had changed , with red slightly in the lead. So I figured a 60:40 blue:red mix for vegetation, and a 60:40 red;blue mix for blooming. I might modify the panel once it arrives, see if I can't drop a dimmer on the blues so I can drop the blue down to help trigger flowering, and then bump it back up a little to provide some extra boost. I've always had poor yield results, especially with tomatoes and peppers, with those 7:1:1 panels. More blue is needed. Other lighting companies realized this and are starting to offer blue-dominant panels to supplement their lacking UFO panels. NASA realized their folly and some of the latest panel design I've seen from them is pretty much 1:2 blue:red (looks like 465 and 670nm.)

Are you growing space-weed? What does the solar radiation at the edge of the atmosphere have to do with anything? I don't think the relative intensities of different wavelengths of sunlight have anything to do with it either. As green and yellow are also more dominant wavelengths than red, your logic suggests you should add lots of those to your LED array. Let me know how that works out.

Where is this stuff saying blue light is better for driving photosynthesis? All the studies I've read say that photosynthesis only occurs at around 50% peak rate on blue light alone - the peak being around 670 nm. Blue light is only required for physiologicial and morphological responses. Again, all the studies I've read say between 8 and 20% of your light should be blue - depending on the plant. Also, flowering is a phytochrome response. It is triggered by the length of the dark period - not by the blue:red ratio of light. Weed is a short day facultative plant. If you have long dark periods you will be able to accelerate (or short nights will slow) flowering but it will eventually flower regardless of the light color/duration. I really don't understand why so many people have this misconception. Show me this latest NASA panel design too. I might have to eat my words here in the next few days. :P

[khyberkitsune]

Are you growing space-weed? What does the solar radiation at the edge of the atmosphere have to do with anything? I don't think the relative intensities of different wavelengths of sunlight have anything to do with it either. As green and yellow are also more dominant wavelengths than red, your logic suggests you should add lots of those to your LED array. Let me know how that works out.

I'm very confused as to how you managed to infer what you just stated from my post.

Where is this stuff saying blue light is better for driving photosynthesis?

http://www.emc.maricopa.edu/faculty/...BK/pigment.gif - something from an educational facility. http://3.bp.blogspot.com/_pFQ0wrHWd1...pectrum_en.jpg - there's another.

All the studies I've read say that photosynthesis only occurs at around 50% peak rate on blue light alone

Depends on the plant being studied - not every plant responds the same - every species has vastly different requirements. For example Tradescantia pallida actually thrives under yellow and green light, which is why it does so well on the forest floor and in well-shaded areas. If you have the materials to conduct a colorimetric analysis, you will see that against a blackbody emitter, a tube filled with chlorophyll actually allows more red light to pass through than blue light. Actually, you can do this with a light bulb and a test tube full of centrifuged chlorophyll - put the light next to your head, hold tube in front of your face - the tube appears to be filled with green fluid. Put the tube between your face and the light, you see mostly red.

the peak being around 670 nm. Blue light is only required for
physiologicial and morphological responses.

Red is required for photomorphogenesis, root development, and for vegetative growth. Blue is for control of certain day-night reactions, seasonal identification, and most importantly, for actual plant growth and bulk. This is why CMH and MH are the recommended primary HID light source by large commercial-scale horticultural operations, and not HPS.

Again, all the studies I've read say between 8 and 20% of your light should be blue - depending on the plant.

Those NASA-conducted studies are old, and they recanted half of them, their new panel design has 33% blue, 67% red.

Also, flowering is a phytochrome response. It is triggered by the length of the dark period - not by the blue:red ratio of light.

That again depends on the species of plant - The phytochrome can also respond to the ratio of red versus blue and the intensity of both wavelengths in order to determine seasonal changes.

Weed is a short day facultative plant. If you have long dark periods you will be able to accelerate (or short nights will slow) flowering but it will eventually flower regardless of the light color/duration.

No, it will not eventually flower without regard to light color or duration unless you're growing a Ruderalis. How do you think we keep mother plants for decades?

I really don't understand why so many people have this misconception.

I think you have the misconception. I do this across the globe and don't get paid to be wrong. If I was wrong and selling a bad product, I'd have been sued already.

Show me this latest NASA panel design too. I might have to eat my words here in the next few days. :P

I knew I should have saved that picture or site link, because my panel manufacturer couldn't believe it either - but they were growing some sort of lettuce (THICK AS HELL) under 1:2 blue:red light. It's on one of the mission pages I was browsing through earlier this morning. I know it wasn't the PESTO mission page. Drat, which one was it?

Rest assured, more blue is the way to g - why else would manufacturers of those UFO LEDs with the "optimized" 7:1:1 ratio be suddenly selling 'supplementary' blue panels - if the ratios were optimized to begin with, why do you need a supplementary panel?

Also, the guy "stra8outaweed" on the forums will testify - more blue = better yield. Check his grows out.