I tried that 🍌 banana test with a portable, battery-or-USB-powered UV-C lamp (tube style; not LED) from Amazon over the summer, knowing that there were a lot of fake UV-C devices around. Using some strips of black electrical tape as a "control" of sorts, I pointed the lamp at the banana and turned it on for at least 5 minutes, maybe 10-15 minutes (I don't remember any more). With no visible changes after that time, I gave up, put the lamp aside, and went to do something else. I was somewhat confused and felt that my test was inconclusive, as everything *looked* genuine: • the tube had the style of filaments that I'd expect and contained getters; • the electronics seemed to consist of a real - if crude - tube-driving circuit and a timer; • the tube might have even contained a visible amount of mercury (a few tiny specks stuck to the inside of the tube - small enough that they could have just been dust); • and I couldn't find anything else that would be creating its eerie blue glow (e.g. hidden "ice blue" LEDs)... 🤔 However, when I returned to the kitchen several hours later, that banana had developed a *very* brown patch covering around half of the side that had been closest to the lamp! 😮 In just a few hours following 5-15 minutes of exposure from that lamp, the banana's appearance had aged by a week or so! (I don't eat bananas, so I'm not too familiar with how fast they go brown in normal circumstances... this banana belonged to my friend/housemate :p) So it turns out you have to wait a while after exposing a banana to UV-C before seeing any effects - and my device does indeed appear to be a genuine UV-C lamp! 😅 (I've been calling it "a tube" and not "a *fluorescent* tube" because I'm not sure if "fluorescent" actually applies to a mercury vapour UV-C tube that has none of the fluorescent phosphors used by typical white fluorescent lamps... 🤷♀️)
@codemakeshare
3 жыл бұрын
Maybe the false peak in the spectrometer is a 2*lambda effect on the diffraction grating, i.e. kind of a harmonic? It seems possible that a very short wavelength would have a second peak at twice the wavelength, and the shown peak seems to be roughly twice the UVC wavelength. The peak also has a distinctive skewed shape, which might mean something (but I don't know if that's significant).
@LutzSchafer
3 жыл бұрын
An effect on the grating since it starts at 350 nm? I doubt it, never seen it on visible wavelengths either. Besides, hello(!!) its visible to the naked eye... Nonlinear effects on the other hand usually cause integer multiples of the emission wavelength, unless you are pumping a laser crystal that has a lower resonance wavelength (e.g. as in the popular green laser pointer where 808nm being converted to 1064 (NdYAG) -> which is then doubled by a KTP crystal). For this you need immense intensities and moreover coherent light. So there is just no chance for any of these to happen. The most likely is the fluorescence of the quartz glass window and perhaps also of the dye material. The light aquamarine blue tint is also present in Hg discharge lamps, but there is also mercury present which may have an emission line in that area.
@codemakeshare
3 жыл бұрын
@@LutzSchafer yes, fluorescence is certainly another possibility - would just surprise me a bit for a manufacturer of a spectrometer in particular to use materials with fluorescence that close to the rated range. Regarding diffraction gratings: it depends on the pitch of the grating - if that is close to the UVC wavelength, you would get fold-back into the detected range. On longer wavelengths, the 2nd/3rd/.. peak are further apart, so they would not necessarily hit the detector. But to be honest, I didn't do the maths, this is just a guess shot from the hip.
@codemakeshare
3 жыл бұрын
@@sdgelectronics Is your instrument an LR-1 from ASEQ by any chance? The plots look familiar. I have one with the extended range down to 200nm, but haven't tested it yet with UVC. I'd assume though that if they sell a 200nm version, that their fibre and couplers are the same for all models and suitable for UV range.
@codemakeshare
3 жыл бұрын
@@LutzSchafer reading your comment again, I realise now that you meant the glass or dye in the LED, not in the instrument. That makes sense, and would also explain why it's faintly visible.
@sdgelectronics
3 жыл бұрын
@@codemakeshare it's an Avantes Avaspec spectrometer. I'm not quite sure what the turquoise glow is on an LED source
@Muonium1
3 жыл бұрын
FINALLY video of a real scientific examination of UVC LEDs! been waiting for this for years on here. would like to see the FWHM bandwidth on a spectrometer and some mineral fluorescence experiments with it too though.
@chrisg6597
3 жыл бұрын
Yippee, a solid state eprom eraser. It's a pity we don't tend to use eproms any more. Seriously, being able to erase an eprom would be an indication of UVC being emitted.
@SeanBZA
3 жыл бұрын
Yes, my first EPROM eraser was an old 125W mercury vapour arc tube, with a 9W flourescent ballast to limit the current to the bare arc tube, safely enclosed in a box, with a drawer to put the EPROM in, under the light. Worked well enough, but had a distinct ozone smell when operating. Now have a much bigger ones with UV flourescent lamps in it, and a timer. Old unit, the timer uses a ZN1034E to do the timing functions.
@lorenzo.c
3 жыл бұрын
I admire your work but I found this video outrageous: after the grief, at university, of trying to understand what those bloody holes moving around in semiconductors are... you don't even mention them? Shame on you! 😉
@christopherleubner6633
6 ай бұрын
Most of the real UVC leds I've seen do not have a window on it. The window materials for these wavelengths are pure silica or CaF2.
@MichaelGuy
2 жыл бұрын
Can I hire you immediately for consultation?
@sdgelectronics
2 жыл бұрын
You can contact me via email from my KZitem page
@debrainwasher
3 жыл бұрын
If you want to take a spectrum from a UVC-source by a fibre spectrometer, you should use a UVC-fiber made from fused silica (SiO2).
@albyboy4278
3 жыл бұрын
60€ on AliExpress 😅
@ferrocene2427
Жыл бұрын
Did you ware glasses Ehrn turning it on just in case?
@christopherleubner6633
6 ай бұрын
Most spectro fibers are fused silica, but the lens and the opics used must be uv permissive also need a silica window detector. I removed the window from the ccd when I needed uv sense capability for a project. UV and deeper IR spectros are very spendy, was lot cheaper to just buy the pieces to upgrade and pop the window off the ccd chip.❤
@andymouse
3 жыл бұрын
Very interesting stuff, can't say i've seen a real one before..cheer's.
@fredflintstone1
3 жыл бұрын
see unable maker video instead of bananas or fruit just use a UV and UVC test card :-)
@sdgelectronics
3 жыл бұрын
Annoyingly I couldn't find my UV test cards
@tinygriffy
3 жыл бұрын
Maybe your spectrometer is totally fine... 🤔 There must be a reason why LEDs with these specs cost 30 bucks somewhere else and not 3 ... There are some interesting UV-C dies from luminous devices at mouser ... maybe you could tuck one into you next order :D ( 896-XBT3535UVCD27501 or 896-XST3535UVA60CE2 for example)
@sdgelectronics
3 жыл бұрын
Thanks I'll take a look at add one in. I've got some UVC test cards on the way.
@tinygriffy
3 жыл бұрын
@@sdgelectronics Jeah, a good measuring device is quite expensive.. some accurate graphs and curves are always nice 🙈
@AhmadLafi-TheFirst
3 жыл бұрын
So you afford to have a spectrometer in your lab but not a 'bananometer'. No excuse for that ;)
@DerangedTechnologist
3 жыл бұрын
As an informal check on the UV emission, you could try minerals that fluoresce but are not sensitive to longer wavelengths (for example, scheelite).
@AxcelleratorT
3 жыл бұрын
Agreed. This is what I was going to suggest and also the reason for my interest in these LEDs.
@AltMarc
3 жыл бұрын
You, simply, can use a fluorescent tube...its phosphor content is optimised for this application.
@davelowets
Жыл бұрын
@@AltMarc Very carefully remove the ends of a fluorescent tube, then shove a few strong UVC LEDs up each end of the tube, and now you've got a REAL "LED Flourescent Lamp"... 🤷🏻
@MikesTropicalTech
3 жыл бұрын
Steve, did you see my message about the problem with the LED boards for the microscope light?
@sdgelectronics
3 жыл бұрын
Yes I'll take a look and see what I've done wrong! Thanks
@LutzSchafer
3 жыл бұрын
Yeah exactly! I got some as well from AliEpress and I think they can't be used for anything serious. Any even very small HBO lamp produces several orders of magnitude more intensity. I also tried if I could smell any ozone. I put the LED's (there were 4 on one CREE copper (or copper plated...) substrate) in a box and let them on for a while. No smell of ozone, nothing nada... I really wonder why they are made in such sizeable amounts and types if they have such limited use, at best.
@victortitov1740
3 жыл бұрын
Ozone is produced when oxygen is absorbing the radiation, which starts at wavelengths below about 200nm (the radiation
@ferrocene2427
Жыл бұрын
Did you ware glasses just in Case?
@power-max
3 жыл бұрын
Odd I find these LEDs on those LED strips on ledsupply.com just recently! IDK why anyone would want such a thing but hey you can buy it! Ain't cheap tho.
@BlondieSL
2 жыл бұрын
For clarity, of those links, which are the TRUE UVC devices and which puts out the most energy? I need to get some that put out real UVC at 280nM~ and as much light output as possible. Thanks in advance.
@RelakS__
3 жыл бұрын
Want to test UV-C LED but you don't interested in the exact wavelength? Buy Hungarian Forint banknotes. The UV reactive parts glow in different colour if you use UV-C (around 254nm) light.
@gnom69
3 жыл бұрын
You could also buy photodiodes to confirm the wavelengths of the LEDs.
@geoffgeoff143
3 жыл бұрын
They appear to give out little visible light? So, a pass filter would not be required?
@paulcohen1555
2 жыл бұрын
Which (cheap) detector diode is suitable for UVC detection?
@thargoid666
3 жыл бұрын
You can try erasing EPROMS with those LEDs
@BlackXeno
3 жыл бұрын
Luckily I had my sunglasses while watching this video
@chuckgoecke
3 жыл бұрын
I've heard that real UVc LED's are world record poor efficiency compared to any other type of LED light source. Like single digits percent.
@pizzablender
2 жыл бұрын
4 milliwatts out, 40 m x 6 volts in, 240 to 4 milliwatts...
@cheri758
3 жыл бұрын
So still uv c fluorescent tubes are better choice
@George-gz5zm
3 жыл бұрын
Where did you get your spectrometer from Steve? Yeah I looked into them myself for door handles. Taken too long in the range of an 30 mins to kill viruses if i remember correctly. Then you have the eye safety standards to consider.
@sdgelectronics
3 жыл бұрын
I managed to pick it up on ebay quite a while ago, but I forgot all about it until I tidied up the lab!
@geoffgeoff143
3 жыл бұрын
They've still got a long way to go.
@neptunefrequencies315
3 жыл бұрын
Great informative video! I was just wondering how you were able to get the UVC LEDs to stick/fit onto the PCB. Were you soldering them onto the board or using a different method to hold the LEDs in place? thanks
@neptunefrequencies315
3 жыл бұрын
Your LEDs are held in place nicely on your PCB! I've tried soldering LEDs similar to the ones you're using and it can be challenging. Any insight would be much appreciated.
@tookitogo
3 жыл бұрын
@@neptunefrequencies315 Didn’t you watch the video?!? At 5:50 you see the reflow soldering process, right after showing the equipment he did it on...
@dieSpinnt
3 жыл бұрын
This was very interesting. Thanks for sharing:) The conclusion that I draw for myself personally is that I stick with my good old chunky UV tube lamps from the EPROM eraser and PCB exposure device. Maybe in 20 years? :)
@gianluigiterraldi9167
2 жыл бұрын
Great video bro!
@sdgelectronics
2 жыл бұрын
Appreciate it!
@dray8047
2 жыл бұрын
Great video, very inciteful! I would appreciate discussing with you more on the construction of UVC LED strip lighting used in commercial public applications. I'm wish to explore any constraints and limitations to find solutions for large installation roll-outs. Please reply with a means of direct contact for further discussion. Many thanks!
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