Looking for compact, high-power UV flashlight. Suggestions?

entomophile · 2019-05-19T00:46:04.000Z

Hi folks,

I’m looking for a UV flashlight with some pretty specific characteristics, and I could really use some suggestions. Here are my needs:

Specific wavelength doesn’t matter too much: ~360-400nm is fine. Any amount of additional visible light contamination is also fine, as long as the UV output is still high.

Output needs to be very high. I’m having a hard time finding objective ratings here (and it doesn’t help that lumens are not useful with UV). For rough comparison, I have a 20W fluorescent UV tube that is fine — but I would say no dimmer than that.

Needs to be able to work continuously for at least 3 hours, ideally 6+.

Batteries must be less than 100 watt hours (just to carry on a plane — I don’t imagine this will be an issue).

Must be durable enough to be crammed into a backback: that means LED only.

I need a beam with a pretty wide angle — a really tight spotlight will not work.

The smaller overall size the better.

Rechargeable. USB charging would be great (e.g., car charger compatible), but not essential. Not necessarily Li-ion, but with this kind of draw for this amount of time…probably Li-ion.

I would be open to DIY solutions, as well; I’m no engineer, though I’m generally handy and could probably figure it out if I could find a source for the parts (bulb, batteries, housing, etc.).

Just for background, I intend to use this to blacklight for insects (see this link for a description: How to black light for insects. - Better with Science).

Thanks in advance for your help!
E

emarkd · 2019-05-19T01:25:30.000Z

Many of us use UV to hunt for fluorescent insects and minerals and other stuff, and do it with a whole lot less than 20 watts. I wonder if those tubes are a lot less efficient than LEDs and that’s the difference? Or if its just “area” - those thing are bigtime flood of course, and most flashlights aren’t quite as floody. I don’t know, but finding 20 watts of power in a UV flashlight is going to be tricky. UV emitters just generally can’t take that much power, so you’re left with building some DIY UV monster so that all that power can be spread around several emitters. Anybody built a Q8 UV yet? 4 Nichia UV emitters should get close to handling 20 watts total I think, although they may not be very happy about it. The Q8 uses standard reflectors + glass so no issues with polycarb blocking. You’d have to rework the driver though, because the stock driver is going to lay down A LOT more than 20 watts and quickly nuke those emitters, but its doable.

If I were you I’d probably just order up a Convoy S2+ UV and go from there. Its not nearly 20 watts and its kinda focused (not fully, still has good spill and you could probably diffuse it if you wanted), but otherwise is a great UV flashlight. But its pretty cheap and would at least let you know what direction to go in next.

BlueSwordM · 2019-05-19T01:26:03.000Z

Blacklights emit a lot of visible light, and are extremely innefficient at emitting UV light in comparison to UV emitters.

So, I would follow @emarkd’s link for a Convoy S2+ UV directly from the manufacturer.

Scientist · 2019-05-19T01:59:58.000Z

I will third the recommendation for the Convoy. Nice and small and really bright 365nm. It may not be sold with the visible light filter. You say visible light isn’t an issue but if you get the ZWB2 filter from Convoy it really cuts out the visible light. Essential for bringing out fluorescence.

fazalmajid · 2019-05-19T02:03:38.000Z

By definition the lumens of non-visible light are zero…

Another recommendation for the Convoy.

EcuBebge · 2019-05-19T02:40:49.000Z

following

Lexel · 2019-05-19T04:07:23.000Z

C8F modded to 3 UV emitters?

Lightbringer · 2019-05-19T04:20:18.000Z

No flashlight will be floody enough based on what you’re describing. You could pull the reflector from a UV S2+ and make it a mule, screwing the pill pretty much right up to the front glass, but you’ll need to make up the difference in battery length.

Maybe even using a shorty tube for an 18350 would still give you the length to shove an 18650 in there. Or at least an 18500. Dunno offhand, you’d have to measure it.

Better might be a DIY approach. Buy a heatsink, buy a few UVLEDs on stars, drill holes to mount 3-4 of ’em in an array, solder them in series, then use one of these donks X̶L̶6̶0̶0̶9̶ LM2577S-ADJ CC/CV SEPIC module (A.K.A. LM2577 CC/CV boost buck converter) to power ’em from a few parallelled 18650s for hours of runtime.

The module in that thread will boost the cell’s voltage to power the LEDs, and you can use the current-adjust to limit maximum current to the LEDs. Done.

Some cheep cheep cheep powerbanks will have a few 18650s already spot-welded to 3-4 in parallel, with wires all ready to go. Bonus is the charging circuit already attached to let you recharge them from any usb supply.

entomophile · 2019-05-19T05:41:47.000Z

Hi everyone,

Thanks so much for all the suggestions. Just a clarification on my intended use – the light isn’t to find insects by causing them to fluoresce, but rather to attract the insects to the light. This is why I’m shooting for closer to 20 watts. While different wavelengths of light will work for some insects, UV light tends to be the most effective at bringing in the greatest numbers.

The Convoy/C8F are good leads, though. My first thought was to just rubber band a half dozen together, though now that I look them up, I see that would be pretty pricey.

The Q8 looks really interesting, though based on your description, emarkd, modding it to run UV emitters sounds a little out of my “capable tinkerer” abilities without some clear instructions. (Though if anyone has done this and can point me to a write-up, I’d love to take a look at it!)

Lightbringer’s suggestion of a ground-up DIY might be the most straightforward. If I go the DIY route, any suggestions for specific UV emitters and where to find them? Emarkd mentioned Nichia emitters for the Q8 mod – would something like this be a good choice for starting from scratch?

Thanks again!
E

Lexel · 2019-05-19T05:43:41.000Z

SST-10, can be used in DD as its forward voltage is very high
or get a 16 AMC driver from me without the MOSFET and drive some Nichias

Lightbringer · 2019-05-19T07:08:20.000Z

If you’re not too picky about a specific wavelength, just hit Amazon for UVLEDs.

LEDWorld usually has ’em out the bum. UV, IR, white, colors, whatever you want.

These Amazon.com are pretty decent.

You could even try something like this Amazon.com for higher power.

Go crazy…

Lightbringer · 2019-05-19T07:09:17.000Z

Hmm, I might just do something like that.

Just Because.

djozz · 2019-05-19T09:28:19.000Z

How about one of these cheap 12V 10W flood lights:
https://www.amazon.com/QUANS-Blacklight-Fishing-Aquarium-12V-24V/dp/B012CUL180/ref=sxbs_sxwds-stvp?keywords=12v+ultraviolet+led+flood&pd_rd_i=B012CUL180&pd_rd_r=719231d4-b0d7-415a-8d35-09b9921ccef9&pd_rd_w=eMSnW&pd_rd_wg=8IgaB&pf_rd_p=a6d018ad-f20b-46c9-8920-433972c7d9b7&pf_rd_r=DAB6FMGD4WWEEFNKK3YT&qid=1558257339&s=gateway
Combine that with a 12V li-ion power pack like this:
https://www.amazon.com/6800mAh-Rechargeable-Li-ion-Battery-Devices/dp/B07PK6M4YP/ref=sr_1_1?keywords=12V+li-ion+power+pack&qid=1558257461&s=gateway&sr=8-1
and you may be in business for 5 hours. I’m not sure how the output compares to a 20W fluorescent bulb.

Edit: I’m not sure about the power pack, this one seems rather small for putting out 6800mAh at 12V.

entomophile · 2019-05-19T22:58:23.000Z

Hi folks,

This is great information. Based on the leads that Lightbringer linked I found a 395nm 20W emitter from LEDWorld; this might be more convenient that 365nm as far as making a front cover that has a high percentage of transmittance (and somewhat less dangerous for my kids’ eyes when we’re using the device).

What sort of heat sink would I need for this sort of emitter? I’m assuming a giant chunk of Al, but as far as size and dimensions… I don’t even have an educated guess.

Djozz, I think lamps like the one you linked are super close to something that would work, though the deal-breaker for me is that they’re just really big and fragile-looking. The 10w ones (like the one you linked) are not too bad, but the 20w ones are ~7” across – not something I’d like to travel on an airplane with. However, the premade power pack idea is certainly appealing, as I don’t have a lot of fabrication tools handy…

E

Edit: here’s the link to the 20w emitter, so you can see the specs: https://www.amazon.com/world-Ultra-Violet-395nm-400nm-Power/dp/B01JLO19SC

Lightbringer · 2019-05-20T01:20:45.000Z

Depends how hard you’d push the LED. A CPU heatsink with fan can be had pretty cheaply. Wanna get fancy, a clicky thermostat (say, 120°–140°) could be used to cool down the heatsink only if/when it gets too warm, letting it air-cool naturally otherwise.

entomophile · 2019-05-20T01:38:46.000Z

I’d probably want to be reasonably conservative with stressing the emitter, since it’d likely be on for hours at a time. Is passive cooling out of the question (in a reasonable form-factor) then? I image a fan would introduce a significant energy penalty for a battery-operated device. Good idea with the thermostat, though – that would be the next best option if passive cooling doesn’t work.

teacher · 2019-05-20T03:37:58.000Z

I realize you are looking for something different, but if you are ever looking for a good 18650 UV light: I have the Convoy S2 Grey 7135*5 365nm light and am very pleased with it.

It also comes standard with the ZWB2 filter.

entomophile · 2019-05-21T05:32:20.000Z

Thanks for the recommendation — and thanks everyone for your advice!

E

Agro · 2019-05-21T06:35:49.000Z

I have Convoy S2 UV with stock ZWB2 and it still seems to output a lof of visible light.
I thought the filter was botched. So I bought another one from a recommended seller - and it worked just as bad.

I had a walk through the woods using just this UV. I chose to walk off the trail to make the test harder. It was hard…but not because it was dim. It was hard because low CRI made it hard to recognise stuff.

Maybe I just expect too much from the filter?
Maybe I’m fooled by fluorescence which adds to visible light?
Maybe there’s another reason?

Any comments?

Scientist · 2019-05-21T14:20:16.000Z

Probably not appropriate to use the term CRI with UV light. That is a visible light measure. Of course there is always some visible light let through by the filter, but I think it is very low. Most of what you are seeing is fluorescence. The amount of UV given off by this light is really surprising so a lot of things fluoresce. Chlorophyll fluoresces red, so grass and leaves look red. Lots of mushrooms and fungi fluoresce whitish and you find out that these are everywhere. And of course you start seeing all the little bits of paper and clothing fibers that are everywhere. These are really bright due to fluorescent dyes that are added. The world just looks different under UV light.