UV triple using Sofirn C8F

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Scientist
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UV triple using Sofirn C8F

I finally got everything together and wanted to post this. First off, I am a real newbie and have relied heavily on the advice and knowledge of the great BLF community. I missed out on the heyday of UV light building here, which was really active in 2015-2016. Anyone interested in UV builds should search some of the old threads here. However there still seems to be some interest and activity in UV lights with djozz testing new emitters when they come out. I came to UV flashlights through the mineral collecting community. If you want to read about it check out this web site Nature’s Rainbow .

Safety notice: UV light is dangerous for your eyes. Do not look into the beam and be sure to wear protective glasses when using a strong UV flashlight. Reflections off shiny surfaces can direct the beam into your eyes by mistake. You won’t know you have damaged your eyes until you get a case of “snow blindness” caused by the UV burning your retina.

I had purchased the Convoy S2+ with Nichia emitter based on recommendations at Nature’s Rainbows and here. If anyone is thinking of getting a UV light I highly recommend this light to start with. Be sure it has the Nichia emitter and get a ZWB2 filter to reduce visible light. While this light works great, reading on BLF naturally encourages one to do more. I monitored the discussions of the Sofirn C8F light on BLF with great interest since it is a triple emitter and there is was a cheap host available. I got one along with their DTP board and driver. And thanks to a recent review by djozz on the Luminus SST-10 emitter here http://budgetlightforum.com/node/57798 I got three of these from Digikey.
These were quite easily reflowed onto the Sofirn DTP board (thank you for the great tutorial VestureofBlood!). It was my first reflow and worked great.

The light went together without too much trouble although I left the wires long and had a hard time stuffing them into the space below the driver. And believe it or not it worked the first time!

This is the view of emitters on moonlight mode without a front filter. Don’t worry I was wearing my safety glasses while taking pictures. The only remaining requirement was to get a filter for the front of the flashlight to reduce the visible light emission. I managed to find a 50×50mm piece of ZWB3 glass on ebay for not too much ($16). I know, the ZWB2 filter is the main one used for 365nm but this glass seems to work about as well. I had to cut the glass down with a saw
and then smoothed out the cuts using a grinding wheel. DBCustom mentions doing this in his builds years ago.
So this is what it looks like with a 42mm filter glass in place

But how does it work? Well I tried wall shots like most of the other beam shots on here but my wallboard doesn’t really fluoresce well. So I put up a sheet on the wall. Because whiteners used in washing it fluoresce nicely this seemed to provide a good way to compare the C8F with the S2+. In this comparison both lights have a filter on, ZWB2 on the S2+ and ZWB3 on the C8F.

On the left is the Convoy S2+ and on the right is the C8F. The S2+ has an orange peel reflector whereas the C8F has smooth reflectors. Unfortunately Imgur did some strange things when converting the images so the differences are not exactly as they look in real life. The left image is the C8F on Low2, middle is Medium and right is High2, only in Group 1. The S2+ is has only one mode.
The S2+ hot spot is a little more spread out than the C8F. On Low 2 the hot spot for the C8F looks almost as bright as the C8F, maybe a little lower. However the Medium and High 2 are clearly much brighter than the S2+. Success! Oh yes, I should mention that both lights have the same freshly charged battery from a laptop pull that I did. With a good high draw battery the C8F could be even brighter. I haven’t had the guts to try it on Turbo yet as I really don’t want to smoke the emitters. From what I have read Turbo can go up to close to 9A. The test by djozz only goes up to 2A for the SST-10 so as a newbie I am scared of pushing them too hard.
As for people who want to know about visible light emission, here is a comparison of both lights without filters. Again S2+ on the left and C8F on the right (C8F on Low2). To my eye they look about the same but in the image the S2+ (Nichia) looks much worse. As the Nichia is noted for having very low visible light emission I have to say that I think the SST-10 is about as good.

Again Imgur introduced some awful artifacts when converting the image. I should state that all of the beam shots were taken with my Nikon D5100 using manual mode to prevent differences between images. So my little adventure has met with success and I have a nicely portable light that I can take in the field with me. Here are some pics of a few of my fluorescent specimens for your viewing pleasure.

This is the same Low2, Middle and High2 settings used in the previous images. They are, clockwise from the top left, blue fluorite from Illinois, yellow sodalite from Canada, pink calcite from New Mexico and reddish bladed hexagonite from New York. You can clearly see the intensity of the fluorescence increasing from left to right. So all in all I am very happy. Hope you enjoyed reading and I will look forward to questions and comments. And again thanks to the inventive BLF community. I never would have been able to do this without your help.

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Uses for UV flashlights

A post about UV lights often generates questions about why one would want to have a UV light. Here are some of the things people do with UV lights, gleaned from past BLF threads and internet searching.

Cheaper lights found on Ebay and other places on the internet (generally less than $20) commonly use inexpensive LEDs with wavelengths of 380nm or higher. While technically UV, the brightness of the fluorescence that we see is directly related to wavelength, with shorter wavelengths and brighter LEDs producing more fluorescence. These days powerful LEDs are available at 365nm wavelengths and these are the best LEDs to look for in flashlights if you want to see bright fluorescence. These LEDs emit in the UVA and UVB wavelengths. Powerful light with shorter wavelengths exist in shorter wavelengths, such as the UVC at 254nm. These light produce the brightest fluorescence in most materials but so far LEDs in these wavelengths are much lower power than 365nm so have yet to be useful in flashlights. Specialized lights (expensive) are made for mineral collectors.

1) Checking validity of currency and other documents. Many currencies now incorporate fibers and stripe that fluoresce under UV exposure. These bills are a handy test for how well a UV light is performing. Cheaper lights with wavelengths of 380-400nm will show dim or even no fluorescence. High quality lights of 365nm show bright fluorescence. TSA uses a UV fluorescent light to check the validity of your drivers license when you go through security at the airport. Certain inks can fluoresce and be used to check documents for forgeries. Forgeries of bank notes, standard checks and travellers’ checks are mainly printed on inferior bleached paper or photocopied. Forgeries will glow under UV light and bona fides will be completely dull. Many newer credit cards have an invisible imprint on the front. American Express uses “AMEX”. If no imprint, the card is a forgery. Alterations of legal documents such as careful erasure or ink eradication and altering paper textures are detectable with UV light. Some products are now imprinted with seals that fluoresce in UV as a protection against fakes.

2) Crowd control. Bouncers use UV lights to check for hand stamps at events.

3) Leak testing. Ethylene glycol used in your radiator or other cooling systems has an additive that fluoresces in UV light. Mechanics can use this to locate a leak in the cooling system. For other systems like oil in your car or refrigerant in your air conditioner you can add a fluorescent tag to the oil to help locate leaks. House inspectors can use this to identify leaks from various systems within the house.

4) Finding urine stains or animal tracks. Urine contains proteins that fluoresce under UV exposure. If you are smelling a urine smell from your pet but can’t find where it is coming from a UV light may help you find it. Animals like mice tend to mark their territory and pathways with urine. You may be able to find where the mice are entering your house using a good UV light. Biologists can use UV lights to track animals. Recent studies have correlated the fluorescence of urine at certain wavelengths to the development of cancer. Not something you can check with your flashlight, see a doctor instead. Rodent hair glows blue white and is easily identifed on sacks or intermixed with grain.

5) Gem and Mineral collecting. Many minerals fluoresce in UVC (254nm) but fewer do in UVB (365nm). However the power of modern 365nm LEDs has revealed minerals formerly thought to not fluoresce that actually do. There is a fairly large community of fluorescent mineral collectors and the availability of powerful 365nm flashlights has been a boon to this group. Some gem materials fluoresce whereas fakes don’t. If you are collecting jade, this might be for you.

6) Amber collecting. Amber (the hardened sap of ancient trees) fluoresces nicely, again due to certain organic compounds. Some beaches are great places to look for amber.

7) Crime scene investigation. As we have seen, certain body fluids fluoresce due to the presence of proteins. A number of UV flashlights are marketed to the forensics industry, primarily at high prices. This property is also used by some people to investigate hotel rooms to look for, uh, fluid stains and how well they have been cleaned. Personally I’d rather not know. You should take a UV light into your bathroom some time if you want to see a crime scene.

8) Antique collecting. Vaseline glass and some other types of glass fluoresce brightly due to additives used to color the glass (uranium in the case of vaseline glass giving a bright green fluorescence). Having a compact and bright UV flashlight is handy when shopping for this type of glass. Some types of colorings used in paintings also fluoresce and can be used to verify the age or validity of painting by a knowledgable collector. You can use a UV flashlight to collect sea glass on beaches.

9) Scorpion hunting. The horny carapace of some scorpions fluoresces brightly under 365nm UV. If you want to kill the ones in your back yard, get a good UV flashlight. Some people actually collect them.

10) Photography. Bright UV light sources have been used in the last few years to investigate the invisible world that humans don’t see but insects and a few other animals do. Many flowers have patterns that are visible only in the UV.

11) Mushroom hunting. Many mushrooms fluoresce brightly.

12) Ghost crab chasing. On beaches south of NC in the US a UV light shows these little crabs all over the beach. Fun for kids.

13) Arson detection. In arson detection, accelerants’ fluorescent glow is greater when exposed longer to heat. Their evidence is not always visible as they are absorbed by the fire but UV light can expose them. Volatile hydrocarbons such as gasoline, grease, paints and others fluoresce when exposed to UV, and can detect fragments of incendiary devices. Ambient light must be minimized for use of UV light at a fire scene.

14) Tonic water glows under UV illumination. So do the spots on bananas. Amaze your friends!

Use your imagination…

Safety notice: UV light is dangerous for your eyes. Do not look into the beam and be sure to wear protective glasses when using a strong UV flashlight. Reflections off shiny surfaces can direct the beam into your eyes by mistake. You won’t know you have damaged your eyes until you get a case of “snow blindness” caused by the UV burning your retina.

Lightbringer
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Tres kewl! (That’s French.)

And yeah, just a few minutes looking at things glow gives me an eerie headache/eyeache, so definitely wear protection.

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Even postage stamps have UV stripes now.

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The SST-10 has a very high forward voltage, on DD you can get to about 1,3A before you run out of battery voltage
to push to 2A you need more than 4.2V

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Cool build and well done on finding and fitting the filter!

Yes, in this host with the excellent DTP ledboard it is probably (what this led does longterm on higher-than-specs current is unknown of course) no problem at al driving the SST-10’s at direct drive.

Scientist wrote:
I missed out on the heyday of UV light building here, which was really active in 2015-2016

I did not realise that it peaked back then. In fact there’s better and easier emitters now, there is good reason to make some awesome UV lights right now, like your C8F.

I have tested another couple of 365nm leds, including your LZ1, some do not disappoint, will post the tests soon!

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I really enjoyed your build and the story behind it. Thanks for sharing, I have never approached a UV build before because I am still learning about UV emitters. This post really helped.

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I originally thought of doing this before with one of my hosts, but after realizing the potential eye damage and all the hazards that go with it, I scrapped the project. With today’s new breed of 365nm UV LEDs from Luminus, LG, Nichia, LITE-ON, Seoul Voisys, etc., a single UV LED is more than enough for counterfeit currency detection and for most of our needs. Unless, you’re a geologist or you’re doing specialized work, a C8F with triple UV LED is an overkill and makes little sense.

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Thanks for the comments guys. I guess you are telling me I should not be afraid of running it on Turbo. I will let you know if I have problems.

Jaded wrote:
I originally thought of doing this before with one of my hosts, but after realizing the potential eye damage and all the hazards that go with it, I scrapped the project. With today’s new breed of 365nm UV LEDs from Luminus, LG, Nichia, LITE-ON, Seoul Voisys, etc., a single UV LED is more than enough for counterfeit currency detection and for most of our needs. Unless, you’re a geologist or you’re doing specialized work, a C8F with triple UV LED is an overkill and makes little sense.

In general I agree. I probably would not have thought of trying this except for the BLF people who always want to try something new and different.

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Jaded wrote:
….a C8F with triple UV LED is an overkill and makes little sense.

That is an excellent motivation to build it! Big SmileBeer
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Scientist wrote:
Thanks for the comments guys. I guess you are telling me I should not be afraid of running it on Turbo. I will let you know if I have problems.
Jaded wrote:
I originally thought of doing this before with one of my hosts, but after realizing the potential eye damage and all the hazards that go with it, I scrapped the project. With today’s new breed of 365nm UV LEDs from Luminus, LG, Nichia, LITE-ON, Seoul Voisys, etc., a single UV LED is more than enough for counterfeit currency detection and for most of our needs. Unless, you’re a geologist or you’re doing specialized work, a C8F with triple UV LED is an overkill and makes little sense.

In general I agree. I probably would not have thought of trying this except for the BLF people who always want to try something new and different.

For bragging rights, sure…but tell me that when you accidentally bounce the UV light right to your own eyes and you’re not wearing your protection googles. It is easy to talk about precaution on the internet but it is also easy to make a mistake and shoot yourself in the foot.

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If you accidentally forget your protection glasses and some or more light bounces back into your eyes, you do not immediately have a problem. In my case at least my retina’s start hurting violently which is warning enough, I have not noticed any short- or longterm effects of that happening every once in a while. Just do not make it a habit.

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Anyone ever measure how much the come-with front glass eats the UV content if you’re not using a ZWB filter?

Imagine it ain’t quartz, but generic Mystery Glass.

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It would be about the same loss as visible light, so a few percent, say 5. The cut-off wavelength of glass is much lower than 365nm, about 300.

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Up to now I only own a single UV light (S2+) and I’m still afraid of hurting my and my families eyes, read something about long term macula degeneration, bought safety glasses therefore. So I’m not sure whether it’s a good idea to use filters, since without them it’s easier to detect if the light is on.

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@Scientist
I like your avatar, would also fit me pretty well … Big Smile

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I am interested in building a high power C band source. My intent is sterilization (not mine).

From research it appears that there are various sources of broad band emitters in this band. For killing bacteria and fungus, this area seems to be the sweet spot. The more power the better.

It needs to be reasonably hand held. But I am looking at the idea of a “whole room” sterilization.

The impetus for this are multi-fold.

People have fungus problems in the house. This could deal with the infestation if set in an area with said fungal infection. Having a contractor in to fix it – $$$$.

This range of the spectrum also kills a wide range of really nasty bacterial material. Some are quite resistant to antibiotics. We are fairly frequently exposed to these bacteria. They are responsible for diseases that can not be cured with normal biological techniques.

A reasonably designed device could prevent a lot of otherwise near immune to everything disease propagation. I would like to make some hand sterilizer stations for the house and a directed beam for using on skin.

I do understand the issues of UV exposure to the eyes. And, long term, exposure to the skin.

I am going to start a new post on this subject. I am posting here to get attention from the people that may already looking at this.

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You might then just want to get a “germicidal bulb”, basically a small fluorescent tube but without the phosphor coating.

I used to use mine to ozonate the whole room. Also helps when you get bronchitis (O3 was the only thing that could stop the incessant coughing).

There were a few articles a few months ago about the benefits of using portable 254nm lights to irradiate hospital rooms to prevent or at least reduce iatrogenic infections.

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@Flashy Mike, yes I’ve set my share of things on fire.

@alternety Take a look at this open access article on using far UVC (207-222nm) for germicidal use Far-UVC light: A new tool to control the spread of airborne-mediated microbial diseases . You would think it would be more dangerous than the longer wavelengths but apparently it is absorbed so quickly in the outer skin layers it is less dangerous for humans than say 365nm. Apparently they are already building small handheld devices for places like operating rooms. Don’t think we will see it in flashlights any time soon. This article led me to a few more that really emphasize that 365nm is not good at all for humans. Between generating melanoma in your skin or cataracts in your eyes, it is something to be avoided. Fortunately I plan on using my flashlight in only short bursts with good eye protection. But being out in the sun is really bad for you unless you are covered up.

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Yes, every risk assesment of UV flashlights must be set against what sun exposure does to you, to put the risk in perspective to every day risks that are out there and considered as normal. That said, these high powered 365nm lights combined with wide open eye pupils in the dark, for short periods probably gets well above the every day risk.

alternety
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Scientist, I have spent the last couple of days poking for all sorts of info on C band UV. The link you gave me on the 207nm – 222nm is extremely interesting.

Aside getting extremely annoyed by the number of products that match 2xxnm on a search (frequently by just deleting it from my search parameters) but when you look the actual material runs from 400nm to the emissions of a burning match. Oddly, these offers all seem to include Chinese text.

As best as I can tell at this point, diodes in the target optimal frequencies. There are some in the upper 200s. Most are quite expensive. Some of the larger wavelengths can impact the pathogens, but lack the benefit at 207 of being stupid proof. That would make it practical to sell a device in the drug store. Big bucks there.

I saw a brief bit that talked about being able spread the spectrum of an led and stretch it across the region of interest. They were talking, I think, about some sort of a filter array that could alter the emerging light from the narrow band input. But I have no idea how that could work. And I may have gotten a completely incorrect information by not understanding.

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Very nice Scientist! Thanks for sharing the great info, sweet build, and interesting site. I would love your light in the woods at night! So many interesting things can be found with my S2+uv that I never even knew about, like big millipedes fat as a pencil and two or three inches long. I think the danger of using these lights outside in a natural setting are way lower than inside, where there are more reflective surfaces. Still, it’s a good idea to be wearing glasses, especially with that awesome triple. As to not needing a bright uv light, you don’t, until you get a decent one, that is. Then it’s flashaholism as usual.