400nm uv “worklight” – need help finding the parts

I signed up for BLF last year because I wanted to build a light for finding amber at the sea. (slowly turning into a flashlight-oholic)

At that time, I realized I did not have the skills for building one myself. Instead, I bought a p60 drop-in with a LedEngin 365nm, and got a C8 size 400nm from fellow BLF member djozz.

Since then I learned a bit more about building and modding lights. Especially the “hands on” parts is no problem. I have built two zoomies with Ir-LED’s, and one Convoy with a normal LED. Therefore, reflowing and soldering is no problem.

However, I still find it hard to figure out the theoretical and technical stuff (divers, PCB, MCPCB, etc)

Therefore, what I need help for is finding the parts for the light – I’ll do the assembly/modding myself.

I have been researching a lot, and have many ideas for hosts and LED, but I don’t know which parts to buy, to make it all work.

What I want to build is a light with:

  • Mininimum three uv LED’s, and a maximum of six. In the range from 390-405nm
  • Water resistant (not waterproof, just to be able to use it in rainy weather).
  • No need for long throw – more like a lot of flood within 3-6 meters
  • Fairly easy to mod - has available parts - has been modded by others here on BLF
  • A budget of max 150 dollars

I don’t care if the light has internal or external batteries or if its 18650 or 26650.

I don’t care how the host looks, as long as it’s fairly portable. So the host could be something like:

Normal flashlight:

Bicycle light:

Motorcycle light:

Lightbar: (for a car)

Light pod:

I actually found this light (click image for link):

that more or less fits my requirements – but I would rather try building one myself.

I also found these LED’s:

SemiLEDs True Violet UV LED (400-410nm)

Violet 3535 High Power LED

3W UV LED 395nm-405nm 180mW

5W UV 400nm-405nm LED

395-400nm Purple Light LED Emitter w/ 20*1.5mm Board - 3.5-3.6V / 700mA

395-400nm Purple Light LED Emitter w/ 16*1mm Board - 3.5-3.6V / 700mA

5w 395NM with PCB

Led Engin LZ1 U6 400nm-405nm Violet 5W LED (you can choose MCPCB at the bottom )

7W Tri-Core High Power Violet LED 395-400nm

5W Dual Core High Power Violet LED 395-400nm

Does anyone want to help me, and be my “project manager”

Bump :-)

I really like the idea of a lightbar/light pod, but I haven't been able to find a lot of info about how they look like inside.

Do you guys think it would possible to replace the leds on this board? Is it possible to do a reflow when there are a lot of other components on the board (click image for the CPF thread) ?

simplest thing would be replacing white led for uv in pretty much any flashlight, just make sure driver is not putting out more current then leds can take, that is all.

For a parts list, it's going to be easier if you choose a host first.

The Supfire you pictured first would be a good choice; it fits your criteria, & you would not look like a GhostBuster carrying it around, unlike some re-purposed automotive lights :D

Djozz has done a bit of UV testing, but I'm not sure if any of those go into the 400nm range.

400 IS not real uv, it is violet, are you sure it will work for amber in the water?

the easiest would be picking the led first, than knowing its size, Vf, and current, look for host that would require minimum modifications.

have you tried any uv led on amber in water before?

The Semileds emitter sounds best, 3535 size, 750mW/emitter at 700mA. I'd use a host like this 7 led SRK clone: https://www.fasttech.com/products/1699/10014338/2418100-7-led-3-mode-1800lm-pure-white-led-flashlight, ditch the leds (they are rubbish), and reflow the Semileds leds on the board. Then, if needed, adjust the thickness of the wires that go from driver to ledboard (the stock wires will be tiny) until you are at 5A.

Lol - you make it sound so simple. But a lot of the multi-LED flashlights i found seem to be hard to mod (at least at my skill level).

400nm is at the end of long wave UVA. I tested both 365nm (Led Engin) and 400nm (some chinese from djozz) - and 400nm clearly returns most florescence from the amber.

I would like to build a light with one of these

SemiLEDs True Violet UV LED (400-410nm)

Led Engin LZ1 400nm-405nm (you can choose MCPCB on copper at the bottom)

7W Tri-Core 395-400nm

FmC - my current favorite for finding amber is actually a 400nm C8 from djozz :-)

I agree - the Supfire M6 looks great, and I found a lot of threads about it here on BLF. But i reeeeeeally like the lightbar/light pod style as I can have a light with 6 LED's - and i don't care how it looks - as long as it puts out a lot of 400nm UV (though a ghost-busters light sounds cool)

And the Supfire is quite expensive compared to the light bars I found. Only problem is i don't know how the boards look on the light bars.

djozz - that SRK would be awesome. What about heat? -I think i read a thread somewhere that they are hard to mod. Can't find the thread though ...

The SRK's are as hard to mod as you like: people don't like the heat path and put huge copper heatsinks in it, and hotrod drivers. These uv-leds run at only 700mA so all that is not needed, just remove the ledboard and replace the leds may already be all that is needed.

Found these Epileds 3535 size 395-405nm leds, 15 dollar for the nine, probably will work ok: http://www.aliexpress.com/store/product/3-Series-3-Parallel-Epileds-SMD3535-Purple-UV-Led-Emitter-Light-395NM-405NM-OR-420NM-DIY/434692_2055578123.html

Ok ... Still don't know about the SRK though

Thanks for the link to the LED's! Seems to be the same type as these

Just to be clear:

The supfire m6 with 3 led's wil give more throw and less flood

And the 7 ledSRK-clone will give more flood?

The 7* will be more floody, & will lean more towards what you are after, although I wouldn't call the M6 a 'thrower'.

Although you will not have to drive the LED's too hard, seven of them will still produce a reasonable amount of heat, & the SRK clones that are available now don't come with any form of heat path; the thin plate with the LED's on it is literally floating.

Here's a mod I did to a 5* SRK clone, so you know what you are in for if you go that route. Obviously, you won't have to do the machining to the back of the reflector, or the spring bypass', etc. The main thing is to get that plate in there, like the original SRK's had, to provide a heat path to the body of the light.

Driver-wise, there are 7135-based OSH-Park boards available, so you can get the current/modes that are right for the chosen LED's.

[quote=HestbechI would like to build a light with one of these

SemiLEDs True Violet UV LED (400-410nm)

Led Engin LZ1 400nm-405nm (you can choose MCPCB on copper at the bottom)

7W Tri-Core 395-400nm


first one is good choice, second one, i seriously doubt it is real ledengin, third is ok led, but you should never buy led like that mounted on a board, cuz i have never seen it mounted correctly, all board i saw only had legs soldered manualy, and heatpad, would barely touch the star. if at all. if you buy a bare led, and reflow it yourself correctly, than go for it, those are not bad leds at all,
i have actually build a uv light out of 4 of these, it lights up white papaer from 50 yards easy.

as for lightbars, their boards usually have all the components on it, so reflowing leds is tricky with these boards, you prbly could use a lighter, on the bottom of the board to reflow leds, but you can also unsolder other components.

I found the same Semileds emitters on ebay: http://www.ebay.com/itm/5pcs-U70-SemiLEDs-410-420NM-Ultra-Violet-Purple-UV-3W-3-4-3-6V-350-1000MA-20mm-/321590284670

Hestbech, Amber what an interesting use for a UV led :slight_smile:

How do you do it? Do just go on the beach (at nigh or day?) and shine the light and if there is amber in the sand it florescence? Or do you look in the water….?

How much have found?

I live far from the sea unfortunately, but if i did live close this sounds like something i could get in to :slight_smile: And who knows i might move closer one day.

I built my UV triple using the horrible P5 from GB I reviewed here:

…and a set of the 3535-sized 395-400nm UV emitters from an eBay seller. Depending on the emitter you go with, as in my case:

If you are selecting an existing light to use as a host, try to get one with the XP-sized emitters instead of the XM-L sized. The first light I tried to use as a host had the LB XM-L-style emitters, and I couldn’t get a board to fit my XP-sized emitters to fit. I had trouble finding a decent and inexpensive triple host for my build. For a purpose-built light like you want, I’d suggest looking at the newer SRKs with the counterfeit XP-L emitters. Those can be had pretty cheaply in some cases. You should be able to reflow your XP-sized UV emitters onto the original board, and since the fakes are driven fairly weakly, you may be able to use the factory driver without mods. I would also count on having to find a way to improve heat sinking, either with some potting, or via an added metal plate.

I decided to give it a try with the light bar/pod. Will let you know on the progress and challenges of the build.

nice find! -And a nice price. But only almost the same - not same wavelength ;-)

cajampa: Yeah it's a nice hobby. Not a lot of people at the beach at night. I like that. When the wind is right I go to the beach at night. If you know where to search there is a good chance to find amber. The uv makes the amber "glow yellow" - best wavelength is around 400nm. I haven't found any really big pieces yet -but a lot of small pieces. Think my biggest piece is around 10 gram. But I got a 192gram piece on display in my living room (belongs to me and my brothers - we inherited it from a relative)

Mouseover for uv:

And from a trip last year (a small piece)

From another trip:


Didn't see your reply keltex78. Thanks for your advise on the SRK and the XP-sized emitters. Much appreciated. But that's one ugly light! - Thankfully you cant se much under uv

And thanks for the link FmC. Nice mod - and great explaining of the steps.

I don't think it gets much cheaper:

3535 395nm with 20mm Star base (several other wavelengths to choose from)

Thanks for posting those pictures :slight_smile: Nice, i was hoping you would do that ;).

I have been struggling for a reason to build me UV light, but this is the first reason i have found to maybe build me one in the future.

I like to run at night and my favorite part of the run is along the beach in the sand right at the edge of the water, the lake is just amazingly beautiful at night and it is always look different.

And it is all thanks to these small lights it is even possible to run on the beach in pitch black :slight_smile:

That refers to the soldering job as well :bigsmile:

(pic from the link)