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Grow room design, HID, fluoro, reflectors, ventilation, ballasts and wiring.
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Prawn Connery
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Post by Prawn Connery »

Intrinsic wrote:Thanks Prawn, My old growing area in the attic between joists is 4' x 8' perfect for this size.

Ahh i forgot abut the low UV thing with leds. tho i think leds can be engineered to produce a wide range of frequencies, but don't know if there are any out there with sufficient UV for our plants. if so perhaps an improvement in yer panel for the future.
So all white LEDs start off as blue LEDs. An electrical charge is put through an anode, which jumps over to a cathode and emits energy at a certain frequency. In the case of nearly all white LEDs, the diode produces a bright blue light in the 450-460nm range. This blue light is then scattered using red and green phosphors which appear as the yellow "coating" you see on LEDs, such as the ones below.

Red phosphor + Green phosphor + Blue light = white (RGB colour).

The more red phosphor, the warmer the white colour. If you look at the LEDs below - which are incidentally one of the LEDs used in the new boards - you'll see the ones on the left are a bright yellow, and the ones on the right are more of an orange colour.

The yellow LEDs have less phosphor coating that allows more blue light through, as well as more green than red phosphor - together making 5000K-6500K (blue or cool) white light.

The orange LEDs have more phosphor coating and more red than green to convert more of the blues to reds, making 2700-4000K (red or warm to neutral) white light.

[image]http://www.nichia.co.jp/img/product/led ... isolis.jpg[/image]

Why am I telling you all this? Just bear with me . . .

The amount and type of phosphor determines efficiency as well as colour temperature (kelvin) and colour rendering (CRI) - all of which have a bearing on plant growth

As most of us know, THC and other cannibinoids are a bit like sunscreen for plants - they are produced in response to UV (not just genetics), and break down under UV, thus protecting the plant - and most importantly, the seed casings. Which is why buds have the most THC. That's the simple explanation.

Now individual LEDs can be produced in colours other than white - depending on the frequency, they can emit almost any base colour.

UV LEDs do exist (both UVB and UVA). They emit UV light and have little or no phosphor coating on them. But UV light is destructive, so UV LEDs - in addition to being very expensive to produce - do not last long.

One of the cheapest forms of UV light at the moment is fluorescent, or compact fluorescent. Mercury vapor lights are also high in UV, but not very efficient. In fact, CFL/fuoro is a type of mercury vapor lamp that produces UV as its base colour, which is then converted to white light using phosphors - which is why the bulbs are a white to yellow-white colour, due to the phosphor coating on the inside.

A few LED companies have developed a white LED based on a UV (or near UV) base light. This light is emitted at about 400nm - which is at the end of the UVA spectrum and start of the visible light spectrum. These LEDs use Red, Green and Blue phosphors to make white light, but they also emit violet light.

These are the LEDs that are used in the new boards. They have most of the efficiency and longevity of traditional blue-white phosphor LEDs, but produce a good amount of light in the UVA and near UVA spectra that is not produced by blue-white phosphor LEDs.

So this is all a long way of explaining why we are using a violet-white phosphor LED and not a dedicated UV LED. Some LED panel produces do use dedicated UVA lights on their boards (usually around 385nm), but they require a separate driver (added cost), are not as efficient, and have a shorter life expectancy, diminishing the lifespan of the entire boards. They also do not add other colours (spectra) to the board, so have no real photosynthetic value.

Ideally, if you are serious about adding UVA/B light to your grow - and there is also the matter of adding too much, which can damage your plants - you would use a UV reptile bulb, or fluoros or CFLs or MH/CMH light.

But even a little bit of UV appears to be beneficial to plants grown under LED, and so that is why this is perhaps the first near UV/UVA white phosphor LED grow panel produced, as we don't know of anything similar.
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Post by Prawn Connery »

bentech wrote:what would you say is the ideal canopy dimension for those panels?


assume less heat is allowing you to keep them closer to the plants than HID allows are you seeing even better results the simple watts to lumen increase over bulbs?
These are designed to be a direct 600W HPS replacement, so two LED boards side-by-side measure 415mm x 410mm (16"x16" in the old money) or 450mm x 440mm (about 18"x18") with matching heatsinks.

The LEDs are spaced quite far apart - further than other boards - at about 13mm (1/2") centre to centre. This provides a wider, more even spread of light, whilst reducing heat between LEDs for better dissipation and thermal management.

The boards need to be tested, but they're built to cover a 3'x3' with a very even canopy - much more even than HIDs, and better than other LED panels and strips.

But they will also be flexible. As they have a wide power range - you will be able to power (dim) them anywhere from 50-225W - simply hanging them higher with more power or lower with less power will realise efficiencies at different canopy footprints.

Two LED panels side-by-side will ideally cover 3'x3', but will also cover 4'x4' at higher wattages (400-450W). However, four panels would be better for a 4'x4' - 5'x5', providing up to 800-900W over 16-25sqft, which is about 35-50W/sqft.

Two panels end-to-end will cover a 4'x2' nicely (40-50W/sqft), while one panel would be ideal in a 2.5'x2' tent (40W/sqft).

We've found that 40-50W/sqft is a good indicator for current LEDs. Some run lower than that (35W), but you never need more than 50W, unless your LEDs are old and inefficient.
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Post by Prawn Connery »

LEDs convert more energy to light and less energy to heat compared to HIDs.

LEDs can be placed closer to the canopy, maximising their efficiency.

LEDs have a fuller spectrum of light than most HIDs (CMH being the best HID), providing more efficient photosynthesis.

LEDs focus all their light down, splaying out at about 120 degrees - all HIDs, such as HPS and MH, lose light and trap heat from reflectors, unless you hang them vertically. For this reason, a horizontal LED grow is much more efficient than a horizontal HPS grow. We're even seeing better efficiencies than vertical HID grows.

LEDs don't need to be replaced regularly like HID bulbs.

LEDs don't lose 10% light output like HPS does after a couple of grows.

LEDs can power on and off instantly, with no ignition and warm-up time like HIDs. Power interruptions do not affect LEDs or their lifespan, nor create a fire hazard.

LEDs are less likely to burn plants. The panels we've designed are also silent and need only passive air cooling.

These are the main advantages over traditional HPS grows.

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Post by Lrus007 »

just a little side note on the fluorescent bulbs.
the 4' long tubes and other tubes that are not bent put off
less UV. because they can coat those type of bulbs very well.
now when you put bends on the tube like the curly fry bulbs
as i call them. the coating does not coat 100% of the bends
in the tube. so a few of those in a grow will add some UV in.
just thought i would toss that in there.
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Post by Prawn Connery »

Yeah, that's right - that's why there have been concerns over the amount of UVB given off by twisty CFLs vs tubes and other lighting. In fact, LED companies tout the lack if UV as being an advantage for their indoor product over fluoros.
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Post by deran »

the diy panel i had in test only consumed 30w with 30 diods and it had a uv and fr diod, so of 30 diods , ionly 1 uv

funny thing , its less "bright" than the fr, you cant see both witgh the naked eye, the cmos tho cought the heat, but not the uv portion

i dont find uv destructive with this test, its the power/amount in ratio to all other bands that matters and that you dont overdo the plants limits

actually, bc tech is moving on, the leds became "too strong" nowadays, that you need to drive em seperatly only for 1 or 2 hours daily, which is enough, with the older weak leds you were able to prolong this time as the total amount of photons hasnt filled up in given time

its like with many things considering life, it can be deadly, but considering you know what you are doing, it will add to life (and fun)
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Post by Prawn Connery »

There are a few different theories on this. A lot of guys are running UVA and UVB for a few hours to simulate peak UV times during the day.

For Emerson effect, they are running far red (730m) towards the end of the cycle to simulate dusk. Both of these require separate channels to drive at different times.
Screen Shot 2018-11-01 at 13.57.47.png
The violet-based white phosphor LED we're using (6500K) has a strong peak at 400nm and a little bit of scattered UVA from about 380nm onwards. When mixed with the LEDs below, the UV peak is modest, but it is a high-energy wavelength that other white phosphor LEDs don't provide, so we believe the constant, low exposure to the plant will stimulate oil and terpene production. For food corps, for example, Beta Carotene and Chlorophyll A both have strong peaks below 450nm, which is where most blue-based white phosphor LEDs peak. Violet-based white phosphor LEDs have two peaks at 400-405nm and 450nm. They also emit a fair amount of energy in the 650-750nm range, which also coincides with the second Chlorophyll A peak. Most low CRI (70 80) blue-based LEDs peak below 600nm.
Screen Shot 2018-11-01 at 13.56.25.png
This is the CRI98 LED we're using - it has very strong peaks in the 620nm range and below 450nm. This SPD chart is the 3000K version, as we're using the 2700K version which has less blue. It actually has very good spectral distribution for plant growth on its own, but is not as efficient as the LED below.
Screen Shot 2018-10-19 at 23.11.37.png
This is the main LED used in the panel. Again, this is the 3000K chart and we are using the 2700K LED, which has less blue and green. There are 300x of these, 90x CRI98 and 60x near-UV LEDs for a total of 450. These Nichia CRI90 LEDs are also nicely weighted in the red spectrum and are the most efficient 3030 LED on the market, with tests showing they are actually more efficient than Samsung's flagship LM301B that a lot of other LED board manufacturers are using.

Once the boards have been assembled and we've tested the spectral distribution and total PAR output, we'll be in a better position to know how they compare to other boards on the market, but suffice it to say, it will have arguably the most complete spectrum of any single-channel, single driver board available - which is what were were aiming for. It will also have a nicely weighted red spectrum with enough blue and UVA to boost flowering and oil production, whilst bringing flowering times down with the help of a little far red boost.
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Post by bentech »

what do you see as the future of development in this area

driving cost down obviously
BUT the ability to build arrays that are 'tune'able is amazing

it seriously seem to me the only thing lacking now is a mike the plant can step up to and say what it would like more precisely...
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Post by Prawn Connery »

Success. Got a prototype up and running and it is performing exactly as hoped. You can see the UVA LEDs, but the high CRI LEDs are indistinguishable to the human eye.
LEDassembled.jpg
IMG_0626.JPG
It's not until you look at the spectrum that you can see the influence. Both these graphs below are of 3000K LED boards. The orange line is the 3000K Samsung LED that's in most popular panels, boards and strip builds. The blue line is the latest board. You can see how, even though they are both 3000K, the blue line has a lot more red in it and a nice little bump in the UVA and near ranges (380-420nm). The spectrometer only goes down to 380nm, so there's probably a small amount of UVA beyond that.

Not a lot of UV is required, as too much causes cell damage. The idea is to provide enough UV to stimulate terpene and THC production.

The orange line is also CRI 84, whilst the blue line is CRI 95 - very close to true sunlight colour rendition.
original_spectrum_normalized-1.png
Here's what the spectrum looks like on its own:
original.png
original.png (33.62 KiB) Viewed 4195 times
And matching heatsinks:
Heatsinkx2.jpg
Heatsinks.jpg
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Post by Prawn Connery »

Heatsinks are optional if running lower currents. On a 30C (86F) day, the board without heatsink hit 47C (116F). The boards max out at 225W, but theoretically could run higher with active cooling. As long as they run below 100C they will last as advertised, but ideally you'd want no higher than 70C. LEDs are less efficient the hotter they run.
IMG_0654.JPG
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