Looking for a UV light (365nm?)

I'm looking for a UV light, mostly for fun but also to detect bodily fluids (of my cats :) ), bugs, scorpions, money detection etc.

I think I want a 365nm, but if it's not the best wavelength for the task, do tell.

I want it to be relatively cheap (not more than 20$).

On eBay I found this one http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=370472749835&ssPageName=STRK:MEWAX:IT#ht_3679wt_1139 with some fun colorful rocks included.

Is it different from the 10 for 15$ at Kaidomain? http://www.kaidomain.com/ProductDetails.aspx?ProductId=2102

I'm also thinking about a drop-in for Ultrafire WF-502b http://www.tmart.com/UltraFire-WF502B-3W-210-Lumens-CREE-Q5-5-Mode-LED-Flashlight-with-Battery_p100633.html . I haven't found any that claim 365nm, but found some general UV like http://www.kaidomain.com/ProductDetails.aspx?ProductId=10572 . Will it fit? Any guesses as to the wavelength?

Also, if there are any 365nm 5mm LEDs I could maybe solder them instead of the regular LEDs of a 9-LED flashlight I have (something like http://cgi.ebay.com/NEW-9-LED-Mini-Gray-Ultra-Bright-Torch-Flashlights-/400184435223?pt=AU_Sport_Camping_Hiking_Lamps_Torches&hash=item5d2cd9e217 )

Also, do I need protective glasses / skin protection for using the keychain LEDs? For the dropin? Any recommendations for such protections?


If you can wait around 10 days ill do a report on KD and DX UV dropins.

This might also be very interesting:


Im inclined to try it.

Beware of the higher powered UV! Use protective good UV blocking glases, preferably yellow lens colored sunglasses (with UV protection).

Quick test report of the DX dropin...

Finds body fluids but i was unable to find cat piss since my cat started to be nice and my wife did a very very through job in cleaning. Almost tought the UV was fake/junk untill checked the toilet and other uv reactive stuff. XD

Atm i lended it to a hunter which is going to test it on blood trailing. Since im going to skiing next week you all will have to wait a bit for the results.

Thanks, I'll wait for your input on the dropins.

Anyone has any experience with the keychain LEDs? Do they have enough power to light something 1-2 meter away, or are they just for close range?

Oh, and there's another interesting option, from Manafont - http://www.manafont.com/product_info.php/tank007-tk566-haiii-365nm-money-note-watermark-detective-uv-light-1aa2aa-p-4435 (seems to be this one: http://www.alibaba.com/product-gs/400287597/TK566_1W_365nm_UV_flashlight.html, so a Nichia UV LED, maybe this one http://www.nichia.co.jp/en/product/uvled.html - NC4U133 judging by the 1W =~ 950mW and square shape).

Thanks for that link. It is pretty hard to find short wavelength UV LEDs. Current Bank of England notes have watermarks that need 365nm light to bring up the security features and they say hardly any LEDs will do it.


Yes, the 365nm-s are really hard to find, especially in a decent price.

Well, it seems I was wrong about which LED goes into the TK-566 365nm. The NC4U133 is a 4-die 15v LED, obviously not this one. So probably the NCSU033B which has more sane specs. But this one says 325mW, so why is the TK-566 speced at 1W? I hope it isn't any lower power LED...

(and looking at the PDFs, I am even more confused - the power dissipation is about 10 times the rated UV power for both LEDs... but maybe that's how it is supposed to be, although it doesn't match 1W either way)

As i understand it, it is rather hard to make short wavelength UV emitters. You can't pot them in the usual epoxy as it is fairly opaque to UV. Glass is right out for short wavelength UV - it is almost completely opaque at those wavelengths. Fused quartz is far from cheap. I'd guess the rest is appearing as visible light and/or heat.

Budgeteer, I too am looking forward to your report on KD and DX UV dropins. Since it has been 12 days, I assume any day now?

Another vendor has been an eBay seller twice as long, has 70-times as many eBay positive feedbacks (304,086), and has a 99.3% eBay feedback rating (vs the other seller's 98.6%), so I bought http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&Item=400174186871 from from eBay seller digitalzone88.

Oh forgive me, i totally forgot.

A quick resume would be:

DX UV Dropin sent by a BLF member to me (which i would not mention since i didn't ask for permission for doing so)


This one is quite bright, maybe disturbingly bright. Being 1W i would say 3W easily judging by current draw. The dropin was assembled in a hurry, worked but could be made alot better.

I would strongly suggest UV protection glasses even for 20 seconds use. For more, UV protective eyegear is a MUST! Not kidding!

I had no problems finding when my cat was noughty. Fluorescent items glow like crazy, white items also. Blood is easily seen as a very matte black patch. Does not glow but it is indeed very easy to spot.

KD UV dropin - http://www.kaidomain.com/ProductDetails.aspx?ProductId=9046

Driven at 500mA i would say it is around 2W not 3.

This dropin is definitely less bright at least half as the DX one.The purlpe variance is noticeable on this one. Looks a bit more blueish. Since it is a UV lamp judging by the light output doesen't really make sense.

The UV light is actually invisible to human eye so any purplish/bluesih beamis strongly unwanted. The KD dropin is also doing it's job well. Maybe better than the DX one since the purple beam is less noticeable.

They might have different wavelength but i have no way to measure it.

In the end, i lean toward the KD version but the DX one is alot brighter if that does even matter.

In the kd dropin the led is:

Anything in particular that you want answered?

Thanks for the info, Budgeteer!

Seems I'll have to go with the tk-566 365nm after all... I want shorter wavelength. (or I'll settle with a keychain LED, if its power is enough for me)

Where did you get the model of the KD drop in?

"Where did you get the model of the KD drop in?"

Umm.. not sure if i understand the question... on KD perhaps?

Why are you seeking the exact 365nm wavelength?

The LED model is not mentioned in the KD product page.

I want the shortest wavelength available at decent price, since many fluorescent materials don't glow in the longer wavelength of the UV spectrum, especially banknotes, as Don has mentioned earlier.

You can see a nice comparison here: http://www.taschenlampen-test.de/reviews/uv-vergleich

If that helps, tiny hair like lines about 4-5mm in leghth can be seen on 50 and 20 euro banknotes. Invisible to the naked eye.

Judging by the link the KD dropin is about 370-375nm wavelength. I used the 20€ banknote.

The DX dropin however is around 400nm wavelength. Hence the diffrence in brightness.

KD's search function do not work well , who knows the amazing things this people hide there...


Great find, arenat!

I can't believe I missed it.

Seems like a better deal than the 30$ tk-566 (also 1W? according to specifications), though I like the 1xAA form factor more. I wonder what LED model it is.

Look exactly as one i have.


Would not pay the 8usd extra for the 501b body.

Comparing with http://www.taschenlampen-test.de/reviews/uv-vergleich and a 20€ banknote could very well be. Dont have such a passport to further verify.

Budgeteer - could you take photos of the dropins lighting a 50€ banknote in a completely dark room?

I have a 50€ from my recent trip to Italy, so I would be glad to make a comparison with the keychain UV I've ordered when they arrive.

Sure thing. But my camera sux. I'll try in a few hours when my wife goes to work to avoid futile attempts to explain what/why em i doing it. ;)

Which side of the 50€ banknote you want in particular?


Top or bottom picture. XD

My reasoning is like the top is backside and bottom frontside but it may vary for others.


Sounds very familiar. :)

Whichever side produces the more interesting results.