help finding cheap UV LEDs?

[Jeffrey Warren]

Hello all -- 

We're looking for very bright, <405nm ultraviolet LEDs for <$10 for a possible experimental LED-based oil testing kit mod. 

Anyone have ideas? We're hoping to radically simplify the oil testing kit's fluorescence system, add a brightness dial, and power it off USB... and make it much more compact. Any tips appreciated! 

https://publiclab.org/notes/warren/08-19-2014/ultra-micro-cuvette-tests-uv-led-and-low-temperature-fluorescence

[Dan Beavers]

Perhaps you missed my post on the air quality list:
--------------

Good Afternoon Mr. Beavers,



I see awhile back you had some interest in our UVC LEDs. I wanted to
reach out & introduce myself, I’m Melanie Bunk the Sales Coordinator for
Crystal IS.



Just wanted to follow up with you on the development of your application
in regards to air purification. Did you have further questions we could
answer for you?



We now have engineering samples of our disinfection line available. We
have wavelengths of 250 to 280nm with two available bins, (1) 8 to 10mW
and (2) 10 to 15mW. Are you at the stage yet where you would be
interested in sampling our product? Please let me know how I can assist
you, I’d be happy to help.



Warmest Regards,

Melanie Bunk

Sales Coordinator



cid:09661A95-80C6-410A-8C1F-38735F7662B1



70 Cohoes Ave. | Green Island, NY 12183

p +1 518.271.7375 x163

f +1 518.271.7394

bu...@cisuvc.com | www.cisuvc.com

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[Jeffrey Warren]

I saw that, but without prices listed, it kind of sounded like it'd be too expensive. But I'll contact them, thanks. 

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[Milad Sakiani]

Hi Jeffery

Interesting concept there.

FYI we make a wide range of violet LEDs at different spectrum

How important is it to have the wavelength under 405nm?

We have 3 LEDs below that are under $5 and range from 405nm to 430nm.

http://www.ledgroupbuy.com/search.php?search_query=violet

The 430nm is going to be the "brightest".  All of the violets are around 3.3v @ 700mA so you would need to adjust your USB power to handle this.

[Jeffrey Warren]

Cool, I'll order a few and try! Nothing below 400nm?

Thanks!

--

[Brian Degger]

If you buy leds as for uv curing of nailpolish they get cheap and low nm ; search for nail dryer or go to your loccal purveyor of beauty products.

as an example:

http://www.alibaba.com/product-detail/Professional-365nm-405nm-9w-12v-uv_60321203200.html which is a array of 8 or so 365/405 leds for under 10 usd :)

Cheers

Brian Degger

@drbrian

--
----------------------------------------
Brian Degger

twitter: @drbrian

http://makerspace.org.uk

http://transitlab.org

----------------------------------------

[Jeffrey Warren]

For reference, the UVC LEDs were $175-585 per unit. 

Thanks, Brian, good tip. 

I ordered some of these, at $5 each: http://www.ledgroupbuy.com/solderless-true-violet-led-405nm/

I posted notes on the research note here: https://publiclab.org/notes/warren/08-19-2014/ultra-micro-cuvette-tests-uv-led-and-low-temperature-fluorescence#Comments

That company also offered a spectral profile for that 405nm LED:

[Jeff Hecht]

In general, you'll get the best prices on LEDs mass-produced for large-scale applications. 405-nanometer lasers are cheap because they are mass-produced for BluRay players. If those nail-polish dryers are mass-produced, and they really are using 365-nanometer LEDs, you may be able to find someone who sells the LEDs cheap. Shorter-wavelength LEDs are available, but they tend to be more expensive. Semiconductor lasers generally aren't available commercially at wavelengths less than about 370 nm.
-- Jeff Hecht

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http://transitlab.org

----------------------------------------

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[Ethan Bass]

Have you checked eBay? There are a lot of people selling 365 nm LEDs for about $0.50. They claim to be "intensely bright" -- whatever that means. 20 mA.

http://www.ebay.com/itm/20PCS-5mm-Round-365nm-Ultra-Violet-UV-LED-Lamp-/221380244317

There are also people selling this flat kind.

http://www.ebay.com/itm/3W-365nm-UV-LED-ultraviolet-LED-chip-light-High-Power-bead-with-20mm-pcb-/301575935747

[Dan Beavers]

Wow, you were right!
"For our disinfection line, we have engineering samples available at $
180/diode."

> bu...@cisuvc.com <mailto:bu...@cisuvc.com> | www.cisuvc.com
> <http://www.cisuvc.com>

>
>
>
>
>
>
> On 2015-11-30 09:07, Jeffrey Warren wrote:
> > Hello all --
> >
> > We're looking for very bright, <405nm ultraviolet LEDs for <$10 for a
> > possible experimental LED-based oil testing kit mod.
> >
> > Anyone have ideas? We're hoping to radically simplify the oil testing
> > kit's fluorescence system, add a brightness dial, and power it off
> > USB... and make it much more compact. Any tips appreciated!
> >
> > https://publiclab.org/notes/warren/08-19-2014/ultra-micro-cuvette-tests-uv-led-and-low-temperature-fluorescence
> >
> > Inline image 1
> >
> > --
> > Post to this group at plots-sp...@googlegroups.com

> <mailto:plots-sp...@googlegroups.com>

> >
> > Public Lab mailing lists (http://publiclab.org/lists) are great for
> > discussion, but to get attribution, open source your work, and make it
> > easy for others to find and cite your contributions, please
> publish your
> > work at http://publiclab.org
> > ---
> > You received this message because you are subscribed to the Google
> > Groups "plots-spectrometry" group.
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> > an email to plots-spectrome...@googlegroups.com

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[Hank Roberts]

You might look at the new Nichia UV leds, which are much, much less expensive than the old ones and getting good reviews:

http://budgetlightforum.com/node/37331

coming out now in decent enough flashlights:

http://budgetlightforum.com/node/42583

the big problem in the past has been excessive visible light also thrown by UV emitters

there are selective bandpass filters that help with that, for each of several wavelength emitters, and those also are suddenly far less expensive than a month or two ago

[Mathew Lippincott]

the lasers work great and the limited experiments we've done with LEDs show much less concentrated fluorescence.

the stability and brightness improvements would be achievable by modding the power supply of the lasers and building with more rigid materials, as suggested.

of all the issues to tackle, it feels kinda weird to choose the most stable and functional part (the laser). 

safety improvement is doubtful.  the LED will throw off more light and probably need to be more powerful than the laser diode.

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