Yet another UV thread

iHearAll

iHearAll

Well-Known Member
Those little Alibaba drivers are super cool, so compact. And 10 of them. Theyre a freaking dollar a piece ....wow.....
 
Randomblame

Randomblame

Well-Known Member
If you want to mimic the sunlight it's okay to use uva and a bit UVB but if you want to increase the terpene/thc content you will need more UVB and less or no UVA. Small UVB diodes on stars pcb's are costly but I've found this strips at a very reasonable price.They use SMD5050 footprint and seems to produce enough UVB for our use.

UV-B 305-315nm, 9,25$/1m + shipping
https://m.alibaba.com/product/60672379170/UVB-300nm-LED-Strip-for-germicidal.html?spm=a2706.8291533.0.0.21cbd071q0Rg0y#module

BTW, I've already tested with 80w/3500k + 6,5w 420-430nm, 1,8w 385-390nm and 6,5w of 655-665nm, 95w total.
The plants were shorter and more stable and the leaves remained much smaller than usual.
Flowers were stony, but not very large and I imagine that it is a bit more potent, but the yield was not as good as expected with only 90g.
One Amnesia F2 Dinafem plant, 60:40sat., meanlined to 8 branches, 64days, unfortunately no pics!
I will remove the 385 and 425nm and replace them with the 305-315nm strips above, but with an additional driver and only for 30-150min./d not again full circle.
 

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canadian1969

canadian1969

Well-Known Member
Randomblame said:
seems to produce enough UVB for our use
Click to expand...
Looks like a great deal, whats it take to power 1m of these? Any idea what they output in terms of radiance?

It's that "enough" part that bugs me, I still think mimicking sunlight's distribution of UVA/B is a good starting point, but now I am hung up on the efficiency of these UV diodes, the ones I bought are at max 6 mW @150ma and 25c
irradiance drops off huge below 310
https://en.wikipedia.org/wiki/Ultraviolet_index
Looking at the UV index page the system seems to be stating 250mW/m2 where the reptile bulb spec was saying 250mW/cm2...

So lets assume Wiki is correct ,I have .42 sq meters and the 4 280's will put out about 24mW total
250mW/m2 * .42 = 105 mW/m2 , but I know that UVB only makes up 3-5% of the total UV

So if 250mW is the total UV package and UVB is only 7.5-12.5mW
Say 5% (if we go high) * 105mW = 5.25mW (so technically I may only need one diode)
the other 100mW has to be UVA.

There's a big diff between cm2 and m2 though, I need to sort that out.
 
iHearAll

iHearAll

Well-Known Member
[
Randomblame said:
If you want to mimic the sunlight it's okay to use uva and a bit UVB but if you want to increase the terpene/thc content you will need more UVB and less or no UVA. Small UVB diodes on stars pcb's are costly but I've found this strips at a very reasonable price.They use SMD5050 footprint and seems to produce enough UVB for our use.

UV-B 305-315nm, 9,25$/1m + shipping
https://m.alibaba.com/product/60672379170/UVB-300nm-LED-Strip-for-germicidal.html?spm=a2706.8291533.0.0.21cbd071q0Rg0y#module

BTW, I've already tested with 80w/3500k + 6,5w 420-430nm, 1,8w 385-390nm and 6,5w of 655-665nm, 95w total.
The plants were shorter and more stable and the leaves remained much smaller than usual.
Flowers were stony, but not very large and I imagine that it is a bit more potent, but the yield was not as good as expected with only 90g.
One Amnesia F2 Dinafem plant, 60:40sat., meanlined to 8 branches, 64days, unfortunately no pics!
I will remove the 385 and 425nm and replace them with the 305-315nm strips above, but with an additional driver and only for 30-150min./d not again full circle.
Click to expand...
I was looking at these yesterday, waited for other members to find them too. I wasnt terribly convinced their authentic uvb but the data sheet says they're cree/nichion made. 10$ isn't much to be out but I think minimum order is 5.
 
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iHearAll

iHearAll

Well-Known Member
canadian1969 said:
Looks like a great deal, whats it take to power 1m of these? Any idea what they output in terms of radiance?

It's that "enough" part that bugs me, I still think mimicking sunlight's distribution of UVA/B is a good starting point, but now I am hung up on the efficiency of these UV diodes, the ones I bought are at max 6 mW @150ma and 25c
irradiance drops off huge below 310
https://en.wikipedia.org/wiki/Ultraviolet_index
Looking at the UV index page the system seems to be stating 250mW/m2 where the reptile bulb spec was saying 250mW/cm2...

So lets assume Wiki is correct ,I have .42 sq meters and the 4 280's will put out about 24mW total
250mW/m2 * .42 = 105 mW/m2 , but I know that UVB only makes up 3-5% of the total UV

So if 250mW is the total UV package and UVB is only 7.5-12.5mW
Say 5% (if we go high) * 105mW = 5.25mW (so technically I may only need one diode)
the other 100mW has to be UVA.

There's a big diff between cm2 and m2 though, I need to sort that out.
Click to expand...
I think you're off by a factor of ten in your math. Convert 240mW/cm^2 to meters first. That's 2.4w /m^2 . then multiply by .42 for your percent used of the square meter. So, you would need 1 watt distributed over your .42m^2 canopy. Seems very possible to accomplish
 
canadian1969

canadian1969

Well-Known Member
iHearAll said:
I think you're off by a factor of ten in your math. Convert 240mW/cm^2 to meters first. That's 2.4w /m^2 . then multiply by .42 for your percent used of the square meter. So, you would need 1 watt distributed over your .42m^2 canopy. Seems very possible to accomplish
Click to expand...
I haven't figured out if its 250mW.m2 or 250mW/cm2 two sources say the same thing "250" but one Wiki says m2 and the other the reptisun or whatever bulb we discussed on page 1-2 which states 250mW/cm2
Which is correct is what I am trying to figure out, then I will do the math correctly :-)
 
canadian1969

canadian1969

Well-Known Member
I want to know if 250mW/cm2 or 250mW/m2 is the correct measure
I cant tell from your charts I would need the data used to make those graphs I guess. I need to nail this down before talking about diodes and power.
 
canadian1969

canadian1969

Well-Known Member
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canadian1969

canadian1969

Well-Known Member
So thats your total UV irradiance A/B combined and the power drop-off below 310nm makes the lower wavelengths nearly irrelevant. From 310-400 there is a mostly even distribution of power.

So lets use 5% UVB (meaning of the total UV irradiance; below 320nm will not amount to more than 5%)
0.3 * 0.05= 0.015 W/m2 or 15 milliwatts/m2 (or 15000 microwatts µW) ;-)

The other 95% (285 mW/m2) of the total UV irradiance can be divided equally across your UVA diodes, most lights already hit 400nm a bit so starting at 390,380,370,360,350,340,320 would be 40.71 mW/m2 each.
 
canadian1969

canadian1969

Well-Known Member
Given that I have also read something about UVA inhibiting photosynthesis, people may want to be care about how much UVA they put into the grow. Some would have to confirm as I cannot find the source I read.
 
iHearAll

iHearAll

Well-Known Member
I found a cheap 310nm diode.
$1 a piece. I may get 16 to see how they perform. They require 80ma. A parallel circuit of 8 powered to 600ma would settle the current at 75ma per diode. Seems safe.

https://m.alibaba.com/product/60348154083/Zhuhai-Tianhui-UVB-311nm-310nm-UV.html?spm=a2706.7843299.1998817009.47.Lc35Bs#show_specifications



I'm looking for 315nm to 360nm now...

And 300

Edit, sorry I keep posting, Lol, bored I guess, fortunately no work for a few weeks. I have inquired about small,quantity "samples" of 290nm , 310nm, 320nm, 340nm. Most seem to be made of epiled tech. Some are labeled with a few differing tags for the wavelength.
 
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canadian1969

canadian1969

Well-Known Member
Yep those are 4-6mw, awesome that they gave that info!!!

I think we might have put this to bed
The only issues are these have been outdoor measures, not in a tent and that the saturation or reflectance within a tent may skew numbers, I dunno.
 
canadian1969

canadian1969

Well-Known Member
I think here is what is really happening from a power level in a 4x4

0.3 W/m2 (total UV irradiance at ground level on a hot clear August 1st Florida day at 1pm roflmao)
1.49 m2 (tent)
0.3 * 1.49 = 0.447 W

So you only have to throw half a watt across a 4x4 tent to simulate UVA in the solar spectrum (UVB being inconsequential as its such a small amount that a few diodes is fine). So you will have to figure out your square footage and the efficiency of each diode, annnnnd take into account height from canopy annnnnd diode distribution/coverage.

I guess where you want to be is some equal division of the energy across 310-390nm , could be 3 or 7 or more wavelengths, but the power output is of the most concern. The more wavelengths the better of course. But still we are only talking 447 mW total (as replicating the Sun).

I guess there will be a part two to this thread, lol.
 
Randomblame

Randomblame

Well-Known Member
sethimus said:
why?
Click to expand...
Why? I don't know but there are a few good amounts here in the forum, but do not ask me where... Search engine will find it.
Everything I know, I have from there.
General consensus was, UVB light for 0.5-2h daily was most effective.
I've tried only 385nm and 430nm, but maybe too much because the results were not encouraging!
 
iHearAll

iHearAll

Well-Known Member
Randomblame said:
Why? I don't know but there are a few good amounts here in the forum, but do not ask me where... Search engine will find it.
Everything I know, I have from there.
General consensus was, UVB light for 0.5-2h daily was most effective.
I've tried only 385nm and 430nm, but maybe too much because the results were not encouraging!
Click to expand...
According to this uva spectrum reduces photosynthesis. So, clearly, if we are going to add uva to these experiments, they shouldn't be on for very long. I'm looking at uva like the initiator of UVB. Any reason to slow down photosynthesis before exposure to UVB? Maybe actually, maybe not.

http://www.fondriest.com/environmental-measurements/parameters/weather/photosynthetically-active-radiation/
 
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