Yeah, you need to know the threoretical radiated efficiency of 285nm wavelength. The chief has made a useful sheet giving you the needed formula and avogadro numbers but he has not calculated the numbers for the lower wavelengths. μMol/s is anyway not the right way to express UV numbers.unkle_psycho wrote: ↑Sat Jul 06, 2019 10:57 amI saw the Seoul chips at digikey, they were about 17e each. I can also get them, but already ordered the chips that I mentioned at the beginning of the thread. I was thinking that 4x4mw would be superior to 1 10mw diode because of coverage etc.Randomblame wrote: ↑Sat Jul 06, 2019 10:08 amSorry, I'm a bit late..
I would use this diode. That's the one recommended in the video and it has 280-290nm and very low output in the UVC range(<280nm). Its a 100mA diode with 10mW output, with a series parallel circuit of we should be able to find a siutable driver. A 5x 1w ebay driver has usually 17v and ~270mA. With 2s3p each diode would get around 90mA and produce ~9mW.
6 of them would create 54mW/s of 285nm.
http://www.s-et.com/upload2/CUD8GF1B_R1.0.pdf
You remember that picture here was used to explain how much is needed and how much time it needs to be on.
Benötigte Intensität und Länge der UV Behandlung.png
54mW is 0,054W if we use this amount of light and look at the chart above we see 0,05W in the 1st green row. Below that you see how long in takes until you have a dose of 360 and 540J/m2. Exactly 2h for 360 and 3h for 540.
The rows below that are for diodes with 300-310nm output. 1000J/m2 is already in the red range with 0,05W of 280-290nm.
Such an ebay driver costs 1,50$ or so. Not the best ones, <80% efficiency but you would use less than 12v so there is enough head room. If you want you could change the 105°C input capacitor against a 150° one. That helps a lot and makes them much more durable. But they are cheap; maybe easier to take a few of them. They run 2-3h per day and should at least run a year or so.
I've downloaded the according pdf from the Seti/Seoulviosys UVB test(there was a download link below that video) but I can still not upload pdf's. Is it really not allowed to upload useful pdf's?
Here is a workaround...
If you're interested download the 1st file below(next evolution ..) and delete the .jpg part to make is a pdf again.
Do you have any idea of how I could estimate the 0.1umol/s power level, and how that relates to the mw/cm2 figure?
UV light works with the dosage princip and should be expressed either in J/m2 or mW/m2 or μW/cm². Yeah, its still a photon but with no photosynthetic use so its useless to calculate μMols and it makes thing only more complicated.
It should probably sound as when he's a smart guy but it doesn't!
Better stay with w/m2 or J/m², its much easier to convert it.
You can easily convert μW/cm² to kJ/m2 by multiplying it by 0,036. You can also use 3,6 as multiplier to get J/m² directly.
10μW/cm²/s x 0,036 is a dose of 0,36KJ/m² or 360J/m2.
Forget the 0,1μMol/s he has mentioned.. you would need to calculated it backwards using the formula and the avogadro's numbers in the picture above to calculate how much watt is needed to get the 0,1μMol/s.
It not neccessary! Only the wavelength efficiency would be useful in some rare cases because its a constant number(μMol/J) we could be used again and again. But using μMol/s with UV makes it only more complicated. I really don't know why he has mentioned it.
If you get 12mW out of 2,45w that would be 0,012w radiated UVB. That's 4,5 times less like in my example with 6 diodes and 0,054w. So you would need 4,5x the time needed in my example and that goes for a squaremeter. Impossible with only 12h the day and with 1,44m² you would need 6,5x that much time. 12mw is simply not enough to get to 360J/m².
I would order a more powerful diode and send the other ones back. If it's not too late you can maybe change them if you contact digikey and tell them you've made a mistake.
They also recommend in that video to use the UVB when the mainlight is off cuz it has no effect on PS. They say together with normal light the blue wavelength would activate a photo repair mechanism which works against the UVB stress.
If I would create something I would try to use it together with my far-red trigger. Far-red triggers are used 5 to 10 minutes after lights off and its predestinated to use it together with UVB when you get the needed dose in the same time.
If you look at the chart from the video it says with 0,3w you only need 0,33hours (20minutes)to get 360J/m². So with 0,6w only 10minutes are already sufficient to get that dose and that case it could be used together with a far-red trigger.
1w radiated UVB in 285nm for 10 minutes would be already a dose of 600J/m².
Pretty much perfect to combine it with a far-red trigger IMO cuz you would get the needed dose of both with only 5-10 minutes.
Pretty sure the wavelength don't affect each other. UVB has no effects on phytochromes like far-red and for far-red and the UVR8 receptor its the same so theoretically it should work when we combine both to profit two times from one single 10-15w light with combinated UVB and far-red. Also much easier to find a siutable driver and its not difficult to figure out a circuit design(series-parallel) to power the all diodes with one 300mA driver.