LED Blacklights vs Flourescent Blacklights?

[Draco]

Since i started testing with approximately 42 hours the generic uv led test fixture fell over on to a strip of foam that borders the glass surface it's on , melted some foam and created a hot spot and then, the out lens did melt, so i removed the cheap acrylic dome and have it back into testing, the LED Engin is still running happily with nearly no luminace loss in either uv diodes. the generic is just that a a low cost item, i think they would be good in a uv flash light or in an enclosed luminary, the optics need to be kept clean or the heat of contamination my cause dark spots that then just melt the plastic dome.

Now i do have a question, does any one know of a supplier for these little domes, preferably made from glass with the same diameter of about 5mm? so i can protect the die from air? the generic has a type of what i could only guess a silicone type goo on the inside to keep air away from the uv led die it's self?

one other thing that popped into my reptilian noodle that i have is with the power density of these devices and close up i would not recommend looking at the source for any length of time, in my tests i have the led's behind me, even though it is UVA i have gotten that sand in the eye feeling that i got a bit too much uv, but that was close to the emitter and these have a wide radiation pattern so people a few feet away i dont think there would be risk,
I have been moving stuff around in my lair and misplaced my camera tripod so i will have pic in the future, but for use outside at an event with lots of florescent paint or clothing around i can see these being viable for hiding them in different areas for different effects and the LED Engin would fit the bill for that and use the generic uv diodes in more of a portable flash light as long as the optics are kept clean.
as stated i am using an older driver made for the luxeon series of leds and uses a buck regulator and runs in the lower khz range and some times is audible as a slight hiss and these where engineered to be used on lead acid batteries as they have a low power shutdown via a jumper setting, other wise they will run on lower voltages.
These drives i have use an MC34063 switching regulator ic. I have one more coming and next month may be another, mainly that i feel once there stock is sold out i doubt they will order more. i know there are small drivers available but i do like these more and the only part that is hand made is the main inductor and that's easy to wind
MC34063driver.JPG

[Draco]

on Friday there was a fundraiser 5k run at the local high school and was helping a friend involved with the project, after taking note that every one was in florescent clothing and would be running at night i ran home and grabbed my two LED Engin leds two batteries and set them up at the finish line having them mounted 2 feet apart and aimed up at about a 45 degree angle from the ground so they would light up runners at the finish line and to my surprise it worked out very well, sadly my camera's battery died so all i got was a few blurry images i will try to up load later but i had noticeable illumination out to atlest 20 feet from the two point sources of UV running at almost full power, i ran them at 910ma, this was my first test for them outside and i am very pleased by the results for this type of event, it makes it so easy to hide or place these in locations where normal black lights would not be practical, with filter glass i think i can make them nearly undetectable and can put them in a line array with the leds being about 2 feet apart.
so my next plan is to skip the cheap ones and go with the led engin with it's glass optic, i have found the plastic optic on the cheap ones if contaminated by dirt or dust will cause the lens to melt and fail, i think my two cheap ones i will make into flash lights as they seem to work better for that application and can have protection for the plastic optic.
both of the better led engin i have had no deaths and the lumin maintenance has been very good, no notice in loss of output with about 40-50 hours on them.
i found 2 of my florescent fixtures and will be comparing them but in terms of portability and needing mains power that they would only be useful in a build it location

if any of you have been on the fence on buying the led engin ones i doubt you would not be happy with them, the point source is i think there biggest strength, easy to hide and can run on battery depending on your driver

[Draco]

got the Nichia NCSU033B Ultra Violet UV 365nm LED II Copper , 540mW for about a week now, not the same power level, i get about 57 mw/cm^2 at about 1 cm from emitter, the LED Engin are still going strong with out a noticeable drop in power. The cheapies are still going as well even though the plastic lens failed and had to be removed the led is still maintaining measured output, if you use the cheap one i would recommend protecting that plastic lens and keeping it clean and treat these like laser diodes, picks will be coming soon, just have not had the time yet

[LaserCo]

this is a good thread, thank you draco for evaluating/testing out the available LED's, I hope to be able to use this info someday

[Draco]

Well I have been running these higher quality uv led's since my last post and they are all operating correctly with about the same output power and on the same Jaycar kit built luxeon star drivers. I just got in long wave pass filter glass from UV Systems to kill off some visible light from the led it's self.
One thing to note about the cheap Chinese made ones, they have all since totally failed and I ran them with in the manufactures spec's so they are not worth bothering with unless you operate them interdentally and keep the plastic lens very clean.
The LED Engin and Nichia are worth the extra money

[ZeroPoint]

Following this thread. I've been increasingly interested in UV leds so this is really good info. I bought 100 3W 400nm leds a few years ago for some projects and had the same lens issue you mentioned. extended use caused a browning in the center of the lens and eventual deformation and detachment. It's ashame too, it's much nicer spending $1 on an led than $35 lol. but I guess that explains the price difference.

[Draco]

I wanted to gibe an update on the leds I got just about 2 years ago
https://www.digikey.com/product-deta...032-ND/4976722

They are still going strong and have great lumen maintenance over the years so if you need 365nm leds that work very reliably.

Sadly they are still 35 bucks each but with these you get your moneys worth, all the Chinese leds I used as comparison died a long time ago, The nicha and LED engine have been great over the years and are well worth the money

[dkumpula]

Yeah, products made with these diodes still reflect that high part cost. Swamidog saw a nice Wildfire display at LDI this year that incorporated a bunch of these. At US$2800/each for the 60W version and US$3,601 for the 120W version they are powerful, but still painfully expensive. I suppose there are many ways to part with a lot of money in Vegas that leaves you with a lot less satisfaction . .

-David

[Draco]

the Chinese ones seem to use a silicone goo under a plastic optic and they just solarize, turn brown and fail, spent some time on flea bay to see if they have cheaper ones with glass optics but heck if you are going to build one, so with the good brand named parts or it's not worth the effort, they are kinda sensitive, so a LASROB or a switching diode I think are needed on the deices, simple switching diodes have work well for a few years, and you can drive them with laser drivers or drivers made just for them and that's the way I would go

[kecked]

When the silicon fails, does it fall off and leave the die still working? IF so, maybe you can place the engine in an air tight box and pump in nitrogen. You can then put some form of optic over them to collect and focus the light....OR. Get the right UV safe silicon and recoat them. At 1.00 a piece it might be worth trying.