4 more 365nm UV-leds tested

Last december I updated my test method for 365nm leds and tested 4 leds (link). With the same method I tested and extra four 365nm leds and put all 8 in one chart. I think that this chart is getting way too busy, so for any more tests in the future I will only plot a selection of old tests for comparison.

I measure the leds in my usual way, I test one bare led, if possible on a DTP-board, cooled very well, starting at low current and at each increasing current setting letting the led settle for a moment before recording the numbers. What is typical for 365nm leds is that upon each current increase the initial new output shows some gradual (slow) dropping, I think it is a temperature effect in the die. Blue leds (and thus white leds) hardly show this but I know that red leds are also very sensitive to temperature.

UV led datasheet output claims are all over the place compared to what I measure. I will not claim that I am more right than any datasheet, for that my method is too indirect I think, but at least it makes it impossible to calibrate my test numbers to one correct 'milliwatt' number. So to create a calibration 'in progress' I defined what I measured compared to the datasheet specs of the Luminus SST-10 as my 'djozz-mW'. And I must admit that after testing 4 more 365nm leds now, the djozz-mW could be somewhat low compared to reality. Nevertheless I will stick to it.

My UV output tests say nothing at all about the lifetime of these leds, the tests suggest that you can easily overdrive some of them for a few times of what is in the datasheet, but I do not test what happens over time.

The 4 leds (no links to datasheets this time, but these will pop up instantly if you google for the partnrs)

Third generation LG 3535-size 365nm led 120deg, partnr. LEUVA33T00RL00 (obtained from the Convoy aliexpress store)

Seoul Viosys Z5 series 3535-size 365nm led, partnr. CUN66A1B (obtained from kaidomain.com)

Ledengin LZ1 365nm, partnr. LZ1-00UV00 (from Mouser, lended out for testing by BLF-member scientist)

Vishay VLMU1610-365-135 tiny midpower 365nm led (from RS-online)

The Ledengin LZ1 has been around for a few years but I never tested it before, and also the LG led and the SeoulViosys led have been on the market for a while, but were not easy to source until now.

The Vishay led I think is fairly new, it is another category: way less output and way smaller die, it may be interesting for someone somewhere somehow that the output/die surface area of this led is very high. At least I found it interesting enough to buy some and test it :-) For idea of size, here it is on a 16mm board:

Here are the test results. As said, I put too much data in this graph, i.e. the Vf data of the Nichia 233B is completely covered by the other lines. I will do better in the future.

My discussion will be short as I need sleep now:

*the Vishay led works fine up to 400mA and even steady, I kept it for 10 minutes there to test, I say 200mW at 300mA is the sweetspot. I made a small BLF348 flashlight with this led direct drive on a 10440 cell (some pictures later), but although the output was very significant, the beam of this minuscule die in an OP-reflector was rubbish. It needs a smooth reflector and then very well focussed.

*The LG led and the SeoulViosys led perform very similar, both in voltage and output, and the output is again similar to the SST-10 tested earlier, but with lower Vf, so in direct drive on a single li-ion you will get more output (±30% more)

*The Ledengin led disappoints, it is a big clumsy led if you ask me. But it may be tougher than any of the others over time, who knows?

As for the amount of visible stray light, the Ledengin has the most, followed by the SeoulViosys, then the LG led, then the SST10. And nothing beats the Nichia's in absence of visible stray light.

Thanks for reading, I hope this is probably not very useful but at least interesting to read :-)

Here’s a little quiz, all these 365nm UV-leds were soldered in one series and get 200mW current, UV-light was filtered out so only stray light can be seen. I underexposed to show the differences in visible light output well:

Great, thanks :+1:
I was just looking at the Viosys the other day.

Good tests, I like this last pictures, it is interesting how they have different visible tints, I would not of expected a yellow visible tint from a UV die.

Great data djozz. I believe your method gives excellent relative comparisons and that is probably most beneficial for most people here. It sounds like none of the leds you tested here failed as a result of your testing, is that correct? Too bad about the LZ1 but I’m still going to put it in something.

Here’s some pics of the BLF-348 with the Vishay led. Later I added a 10mm ZWB2 filter. I think that this led will be swapped again at some point.

The tiny pill with heavily trimmed and drilled ledboard, had to remove multiple shorts from led-pads to core by scraping the side of the dielectric layer.

The result. Later a ZWB2 filter was added.

A peek inside. You can already see why a OP reflector does not work: the OP texture is larger than the die!

The beam. The led was not perfectly centered but that would have hardly mattered here.

Thanks for the great comparison, I have a SST-10 laying around just haven’t found the time to use it.

Really great info. Thank djozz.

If I follow correctly, that triple Seoul Viosys Z5 with board package at KD is quite a deal. With discount code, it should come in under $14USD delivered. Now if someone would provide a C8 size UV filter (would like to swap the UV emitters into a C8F and use the base for a tube light).

Except that the optic does not have optimal UV-transmittance. I have no numbers but it is at least a lot worse than glass. If you loose 40% (I make this number up) because of crappy transmittance of the optic you loose the advantage of good leds.

If I would have a C8-size UV filter, I would make Sofirn C8F with these leds.


Hence the swap I mentioned. Good idea to mention that though. I was just thinking the 3 emitters alone for under $14 is a good deal. Plus you get a nice triple MCPCB and optic for other projects.

I can feel a triple UV emitter build coming on :smiley:

I’m trying my luck at alibaba atm for 20 pieces of 40mmx2mm ZWB2 filters. Will get a quote on monday, could be affordable or not, no idea…

Amazing work and invaluable info. You have done it again djozz. Thanks. :beer:

Thanks Steve, I’m not sure about the ‘invaluable’ though, UV led use is a pretty obscure corner of an already obscure hobby. Without these tests, I’m sure the world would keep spinning as usual.

Already got the quote in for 20 pieces of 2mmx40mm ZWB2 filter (fitting the C8), And I’m a bit double about it. They cost $9.50 each, with 50 dollar shipping. So that is an investment of $240 dollar which is not nice (I hoped for under 100).

On the other hand, if I could buy them for 12 dollar plus shipping (which is just $1.80 from my place to worldwide), I would buy 2 of them without hesitation.

So if I know beforehand that I would sell 17 of the 20 pieces, I would do it, but I doubt that there’s interest for 17 ?

Edit: I started an interest list:

I will take two djozz.

Just to be sure about my reading skills. At this moment a black C8 with an LD1-driver with no modes (eh, 1 mode) is useless lying in a corner. Do you mean that without risk I can put in an LG UV-led from Simon?

Yes, you read it correct, provided that it is mounted on a DTP-board it will run in any direct drive situation with a single li-ion, so the LD1 should be fine. With the disclaimer of course that I do no testing on the lifetime of leds when driving them out of specifications.

Thanks :beer:

Edit (almost one week later): Well, that UV-led is on it’s way. Can’t wait to team it up with one of your ZWB2 filters.

I hope for an obscure but interesting new type of light: the UV-thrower.

Btw, the ordered filters should be underway by DHL at this moment, tracking says underway from Le Havre to Netherlands.