Huh? This bulb was tested against a htg uv bulb and was obviously superior. Why do you need more then that? Also led come in Kelvin and nanometer. A plot would just show what the card already did. It’s in a uv nanometer.
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I can capture a spectral plot (not to distract from the work done here, just for the additional information). Which bulb(s) specifically? I’ll order one up.
For the industry leaders, the individual LEDs were relatively expensive the last time I had looked. Also, the output half-life remained relatively poor. Although, LED tech has been making fairly rapid efficiency, cost, and lifetime improvements.
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Yeah, I am not discouraging your testing at all, far from it, in fact I have learned a lot from it. I am just curious as to what the actual output is of the UVA/UVB and if there is any UVC. As I say, just the fact that it appears you have a cheap light with UVB output to me is surprising given what I thought was the situation with the actual diodes. That’s good!
Well I guess if you test the light Skiball is using, then we would have both his UV card test AND a spectrum plot. This way we hopefully might be able to determine the amount of each band, and also the accuracy of the card. Which if it IS accurate enough I think is a freaking awesome find.
Was the light link posted.
BTW if you have a spectrograph that will capture and measure the non visible parts of the spectrum with accuracy, I am soooo jelous.
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Hey N_L!
That’s the one I have too.
I’ll pull up a chair…
Thanks!
btw, @slain these 5watt lights have nearly the same output as the bigger ones, perfect for micro grows,
Hopefully this weekend I can do a side by side.
Would not be surprised to see readings in UVC as well, might explain the low cost?
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UVC is a serious eye hazard is the thing, it’s one of the reasons I would like to avoid it if possible. I’ve had enough eye flash burns from welding to know UVC does bad shit to your eyes. Also I like to be able observe my plants at length without the need for sunglasses 
I am almost certainly going to check these out, as soon as I have my other experiments out the way 
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Too bad I can’t post in less than 20 characters.
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Ok, I’ll get one of those off of Ebay (E27 10W Ultra Bright UV Ultraviolet Color Purple Light) and will report back to this thread. Inexpensive enough.
And, one of these (5W E27 UV Ultraviolet Purple LED Spotlight), as well.
edit: I see they are from China, might take awhile to get here though.
edit: Ordered. Will also get one of these as a comparison:
Similar advertised power but also advertises the spectrum.
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Depends if the get shipped on the ‘slow boat’ or not. Honestly I can find no rhyme or reason to shipping times from China, some things turn up in days and I’ve had stuff from Banggood take months! All shipped via the same Chinese EMS courier.
Sometimes the sea freight gets here before air freight does! And if it’s not as advertised it’s basically a write off.
The cost of doing it on the cheap I guess.
If you don’t mind me asking, what instrument are you using to measure? And how do you find it? I’ve spent many an hour looking through older but excellent Minolta spectroradiometers, but they only measured the visible spectrum, and more suited to luminance and chromaticity testing. Unfortunately now I don’t do that kind of work any more it’s a lot of money to stump up to satisfy my curiosity for grow lights! I’ve even considered using some diffraction grating to make one, but have concluded that to get sufficient spectral coverage as well as high spectral dispersion to make it actually useful for measuring non visible bands is all but impossible.
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Been my experience, as well. Could be a week, could be a month.
This one with a 100nm slit (BLK-CXR-SR):
https://www.stellarnet.us/spectrometers/black-comet-sr/
Pretty broadband with good resolution.
I had purchased the spectrometer second hand. Bought a $$ custom fiber cable, a cosine correction optic, and a calibration source. While you can save a lot getting the spectrometer second hand, it starts to add up when adding the needed accessories. Not a handheld device. Instead a benchtop “lab” type device.
Ebay is a good source for such secondhand industrial / scientific gear. Sometime you’ll find a gem. But, you have to be very careful knowing with what you are looking at and what you are getting. Like buying a classic car…
Not sure how good the calibration would be for anything below 380nm or so since the calibration light source I have isn’t really that good for that range. But, the peaks will certainly be there.
This thread has some more info from some past measurements:
I’ve look at those as well. Very nice. In the end, went with the laboratory spectrometer to gain the flexibility and range. Disadvantage in my case, not handheld and a bunch of data manipulation.
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Nice! So a serious instrument! I was semi expecting one of these new hand held devices. I got nerd envy man, I can’t deny it. This morning I was looking at a Barco 100K lumens RGB laser projector that is capable of projecting pretty much the entire spectrum,from non visible UV, to IR onto screen. UV and IR are sometimes used in high end projectors for thermal HUD simulation in military simulators amongst other things. Anyway… all the while I was thinking to myself… man this would just make the worlds best ever grow light. 
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@slain grow under a series of projectors with a different movie on each, running an infite loop – then rate each movie by the quality of flowers it produces. 
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Measurements for the
E27 10W Ultra Bright UV Ultraviolet Color Purple Light 160LED Lamp Bulb 110v
(18 inches from center of lamp)
Spectrum bins:
Calculated PAR metrics in umols, DLI in mols/12hours:
tbd
Listed as 10Watts. The actual power consumption measures 3W as measured using a kill-a-watt meter.
Photopic Parameters (18 inch distance):
With the plastic protective cover removed, the transmitted irradiation improved slightly (18 inch distance):
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Measurements for the
5W E27 UV Ultraviolet Purple LED Spotlight Bulb Home Lamp Light AC 85-265V
(18 inches from center of lamp)
Spectrum bins:
Calculated PAR metrics in umols, DLI in mols/12hours:
tbd
Listed as 5Watts. The actual power consumption measures 7W as measured using a kill-a-watt meter.
This one, with the 5 LEDs, actually appears to have a higher output (at the center) than the one with the 160 LEDs.
Photopic Parameters:
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Thanks for sciencing!
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Thanks NL, nice work.
UVA only.
It sure fools the pet shop UVB sensitive card.
Weird thing is I have 7 led 3 watt “Full spectrum” bulbs 2 red 2 blue 1 ir 1 uva and 1 6500k white and I get no readings from the card at 12". That white bulb puts out serious lux.
Guess I’ll be sticking with reptile bulbs after all.
Thanks again.
btw Just curious, was the 160 led bulb tested with the cover on?
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Yes, measurement was with the cover on. Didn’t realize it could be removed until you asked. Single point directly under the center 18 inches distance. Would you want some measurements with the covers removed? Easy enough since it’s still set-up.
Also, that particular lamp only draws 3W at the plug. Also, the listing doesn’t specifically list the spectra. It is entirely possible that the manufacturer swaps in different LEDs that are “somewhere” in the UV range depending on whats available at the time.
I couldn’t really find much on what range those cards detect. Other cards that I’ve seen while browsing around tend to indicate a rather broad range for detection, something like 200-400nm.
FWIW, there quite a few different LEDs that can be purchased that address different but rather narrow bands. Even the near-end of UV-C are available from what I can remember.
From looking at the two lamps, the smaller 5 LED version appears to utilize the more modern gull wing lead style of UV LEDs. And, the output also appears to be more intense while drawing 7W from the wall plug. The center point measurement also shows a greater irradiance. Better build quality, as well.
As per UV-A vs UV-B, there are some good discussions to be had…
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Sure, and thanks.
Skiball said
Try it with the cap off it’ll prob put out a lot more.
Though I don’t have pics, Skiball was right, the card test seemed slightly darker.
That 5 watt is of the same construction as the 7 led 21 watt full spectrum bulbs I’ve been using.
I’ll do a test with my lux meter and the card as I don’t recall the output.
btw my grow buddy, who doesn’t use uvb, just harvested the sisters of “F” in my Ebner experiment.
“F” has been under that 160 bulb for almost a month and I just now chopped her and put her in the dehydrator.
Maybe we’ll have a smoke report this weekend!
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Awesome effort there bro! Interesting to see that it’s more or less as you would suspect for such a low price unit. I would have been amazed and stoked if there was significant UVB in there given the price of UVB LEDS. Also as a result it will be interesting to see if UVA on it’s own has a tangible effect and what that is. I’ve been thinking about the feasibility of striping off the UV shielding glass off some xenon headlight bulbs as they should in theory output a decent chunk of UVB without excessive heat and last a lot longer than terrarium UVB lamps.
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I’ve updated the prior post to include the output parameters as measured with the cover on vs off (for the 160LED lamp). There is a slight improvement in the measured irradiant output.
As a note, the calculated photopic values assume even coverage over a m^2 and, hence, it appears to be greater than it actually is in reality. What is being measured here is a point value at the center of the lamp. The spectrum will not change but the measured power will decrease as you move away from the center of the lamp.
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If this hasn’t already been posted:
“The effect of ultraviolet radiation on the accumulation of medicinal compounds in plants”, Zhang, et.al. 2009
10.1.1.542.2383.pdf (553.8 KB)
We have seen that the contents of medicinal substances of many kinds in many plants are increased by exposure to ultraviolet radiation, and in particular UV-B radiation. This effect is not always regarded as a stress phenomenon, as in many cases the increase in the secondary metabolites can be achieved by radiation so low that they do not negatively affect growth, and do not result in any visible damage. Thus, in order to make the production of medicinal plant substances efficient, it may be advisable to try exposure to ultraviolet radiation also in cases which have not yet been investigated. In some cases UV-A or UV-C radiation may be more suitable than UV-B.
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