Intl-outdoor's 3535-size 365nm UV-led on 16mm Noctigon (Royalighting RY-3535P)

This is a test of the newest 3535-size 365nm UV-led sold by intl-outdoor on a 16mm Noctigon XP-board. It is a chinese led made by ShenZhen Royalighting Technology co.,Ltd. The led is not sold for cheap ($16.28 shipped) so you will expect some performance :-) . Let's test that! To make this test directly an unfair exercise, I will compare it to the high performance Ledengin LZ1 365nm led that costs two and a half times that price at the moment .

As you can see the whole led build looks a bit messy, far from how neat the average Cree led looks, or that Ledengin led. On top of that, the led dome was dirty upon arrival. When fired up, apart from the UV, there's a white/greenish glow of visible light. The Ledengin LZ1 365nm led also emits some white light, but a bit less than the RY-3535P.

Here is some data from the spec-sheet (thanks to DCBstm who send it to me, he had asked Hank for it :-) ) . So at 350 mA it should output 120 something, I make that mW. Sorry for the low quality graph, it was better in the pdf, but you can still see that the 350mA should be reached at very close to 4.0V.

The tests.

Of course I could not measure the output in my integrating sphere because the luxmeter does not see 365nm light. UV-light is measured in radiometric power, so in watts, and I do not have a light power meter. So to turn a luxmeter into an improvised 'radiometric power meter', I used this set-up:

The ledboard was mounted on my cooled copper ledboard-mount, a reflector was placed on top of the led, a piece of plain copier paper was on top of that, and last a PMMA aspheric lens. The luxmeter was mounted at a fixed distance above the lens. Copier paper has a whitener added that converts a broad wavelength band of UV-light into visible blue. The luxmeter sees the fluorescent blue light, and the amount of fluorescence is a measure for the amount of emitted UV-light. The aspheric lens was added mainly to absorb remaining UV-light to prevent damage to my eyes during the test.

This set-up I think does provide a descent measure of radiometric output, and the measurements relative to each other should be accurate, but the numbers are of course in no way calibrated to real milliwatts yet. So to get a rough idea of how the measured numbers relate to milliwatts, I measured my Ledengin LZ1 365nm zoomie using the same setup: I removed the lens of the zoomie, mounted a reflector on the led with tape, put, as with the RY-3535P test, the piece of copier paper on top, with the PMMA lens, and measured the output with the luxmeter at the same distance as with the SY-3535P led-test. The flashlight runs the LZ1 at 1A, so the output should be about 1000mW of radiated power. In the test-graph below I plotted the output of the RY-3535P as a percentage of the output of the Ledengin LZ1 running at 1A, so you could read it as a percentage of 1000mW. Do not expect this kind of calibration being anything near accurate, but as a rough estimate I think it is not wildly bad :-)

Here is the output graph:

That differs a lot from the spec-sheet, at 4V I should expect 350mA current, but this led does 1.1A. What measures about correct according to the specs is the output power at 350mA: if you see 100% as 1000mW (see the considerations about that above) it is about 130mW, the number in the specsheet is 120mW. But this led on a Noctigon goes way higher than 350 mA :-) .

For inside a flashlight I would run this led at 0.9-1A, that is more than 80% of the maximum output. On a li-ion with a lineair NANJG-type driver with 3x7135 chips this led will have a great output (about 350mW OTF ?). However, no longterm run-tests have been done by me so don't blame me if the led fails at some point.

Small mod.

I had a small 16340 EDC flashlight leftover with a 2x7135 NANJG-driver in it (so 700mA), I soldered this led in and got a nice 5%-25%-100% UV-light :-) .

Here's a comparison with the LedenginLZ1-zoomie (at 1A, it should have more than 3 times as much output), picturing my hobby-mess . Mouse over for the LZ1-zoomie at zoom out:

The zoomie zoomed in is no comparison, it is a lot brighter than this new mod.

Here's a close-up of a 5 euro bill, with green, blue and red fluorescent fibers, mouse over for the LedenginLZ1. The red fibers only show up in red if the wavelength is close to 365nm, at 380nm they are not red. So indeed the RY-3535P emits at the right wavelength.

This is interesting. In real life the comparison shows that the RY-3535P led emits more visible light than the LZ1, (you do not want visible light because it masks the UV-effect) I wanted to show that in the picture. But after taking the above picture, much more striking than that is a purple near 400nm haze (our eyes do not see that, most cameras are more sensitive to near 400nm light than we). So the RY-3535P emits more light closer to 400nm (at the side of the emission spectrum) than the LZ1 does.

Bonus test.

Because of the different type of illumination that the two leds give that are both supposed to emit 365nm, and of course just because I can (that is what hobby is about after all :bigsmile: ) I had a go at measuring an output spectrum for both leds. I used my ancient Zeiss monochromator for that.

I aligned the flashlights well, pointing to to entrance hole and I did the same trick as before: I taped a bit of copier paper over the exit hole of the monochromator and placed a luxmeter right against it. I used a slit of 0.3, this transmitted enough light through the monochromator to be measurable, and still provided a good defenition of the output spectrum. My monochromator is a few nm off, so I corrected the data for that by calibrating the monochromator's transmitted wavelength reading with a 405nm laser. This way my wavelength accuracy should be within 2, probably 1 nm.

The assumption is here by the way that a 350nm photon causes the same copier paper fluorescence as a 400nm photon.

The absolute output values that come out of these measurements have no value, I corrected the two output-spectra to each other, so that the surface area under the graph was roughly the same (thus in the graph they are 'given' the same output power, to show the respective wavelength distributions best, does this make sense to anyone?).

Here are the measured output spectra:

Well, that shows some difference in quality of the two leds. The LZ1 has a narrower peak at about 367nm, while the RY-3535P has a bit wider peak at almost exactly 370nm. And that is only just within specs. And the RY-3535P has indeed more output at the flanks towards 400nm.

That was a fun test :-)


I think this is a great led for a good price. It does not compare favorably to the much more expensive Ledengin LZ1, but it performs very well on its own I think, with the added convenience of a standard XP-G footprint. I do not own one of the Kaidomain 365nm drop-ins, but my guess is that this led outperforms it clearly. Others will soon test that, I'm sure :-)

Thanks for reading!

Thanks for the info! I especially liked the monochromator test. :slight_smile:

Thanks djozz. I was waiting for you to test this.

I put one in a quick p60 build and at 700ma it’s doing great. Here’s a Canadian 5 dollar bill. (old one)

This is in my kitchen on a blue table with the ambient lights on. From what I understand this bill only lights up in the 365nm wavelength. (I’m sure there’s some variance)

Thanks again for your test.

thanks for the test , i believe 1.5Amps will be fine on copper for longterm use.

Great information. The only thing I can comment on here is that in the LED ENGIN spec sheets they show a migration away from 365nm when current is away from 300mA or 700mA. Between these 2 it is lower, under/over these numbers it is higher. So if you are driving the LZ-1 at 1000mA it should be around 3nm over 365nm, which is just about exactly where you show it. :wink:

Still, I’m pretty impressed with the SY-3535P emitter and will gladly use it in a similar small host when it arrives. Should see it any day now, as it’s been over 2 weeks since I ordered it.

Thank you for these tests, the graph information is exactly the kind of visual I need, as reading it all is somewhat confusing. :slight_smile: Gradually learning though, and largely due to your efforts. Again, Thank You!

Another useful review by djozz. :beer:
Int’l outdoor state it’s wavelength rating: 365-370nm, so about right. I guess your monochromator working perfectly, thanks for the bonus :smiley:

And it occurred to me, my Kaidomain P-60 drop-in may actually use the same emitter. It can use multiple cells but is limited to that 300mA range. The higher the Voltage in, the lower the mA out. So while this Intl-Outdoor emitter is on copper and can be run with a varied power supply, at similar output current it seems pretty much the same thing as the Kaidomain UV light.

I’ll get close-ups if possible when I have both in hand.

Edit: The Kaidomain emitter is a twin-emitter set-up, not anywhere close to the same…

Thanks for doing this testing. Looks like you had to use more ingenuity than usual, but I don’t see where you had to fudge very much. All your logic seems pretty well grounded to me.

And of course thanks for taking the time to write it all up and share it with us in such a good format.

Amazing work again djozz. Thanks heaps.

Thanks for the test. I should be getting one of these any day now for an A/C leak detection light build.

I went ahead and opened up the Kaidomain P-60 drop-in. They had an R150 current sense resistor on the buck driver, so I stacked an R056 on it. Put it back together with 22ga leads (it had like 28 ga)

Where it was pulling 300mA at the tail, it’s now pulling 470mA. And is considerably brighter! :slight_smile:

Thank you very much for the testing and writeup.

You write in such great detail and clarity about the considerations you make underway during your testing that it is always i pleasure for me to read these tests.

Thanks to you all for the nice comments again.

I have way more time to think of what I am going to do for the hobby and how and why, than I have actual hands-on time for testing and modding, I think that you can find that back in the write-up as lots of thoughts and considerations about what I did.

Without people like you and many others here none of us would have a grasp of this hobby.

so which centered gasket fit this led?
xpg or xml?
want to make a 16340 UVight :slight_smile:

The xp centering disc will work. It didn’t look right in a p60 so I didn’t use one. I just set the reflector over the led.

Just ordered a pair of these. Also ordered 2 of the same looking ones from an ebay seller to see if they’re the same.

Thanks for the testing and putting this all together.

CK, which ebay led? Can you give a link?

These have been popping up ebay for around $5 shipped - says 365nm as well. Anyone has tried these?

That looks like one mangled xb-d… like they pulled the dome off and scraped the phosphor ir…

I almost got those to but decided against them.

I got ebay item number 321464744098