UV LED Strip Advice please

bryans_tx

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Hello all;
I wondering what advice you guys and gals can offer concerning UV LED strips.
There are quite a few vendors out there in the wild.
If it helps the conversation, I am also interested to learn what has NOT worked lol!

Anyway for starters, I see the SMD5050 highly suggested. OK.

I also see adverts for the voltage they operate on.

Funny thing is, I have a lifetime as a career electronics tech. And so that is why I know - I should ask instead of making my own decision lol!

I look at the advertised spec's with a stink eye, you see. (pun intended)

I know of one You tube video where the box uses 24v power. So, ok.
Is this because those UV Leds are better quality - have a ceratin specification I should pay attention too ?

I can order from places like digikey or mouser, and in fact I feel better about them as sources compared to the Zon of Ama.

And YES I soooo regret having sold my prior UV light box I found on craigslist and was puportledy made by a Monk. HOW COOL IS (was) THAT ???

A donation of a 8x10 contact frame will bring you an awesome after-life BTW.

In the meantime, Please enjoy these Horses.
 

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Bushcat

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5050 covers a huge range of devices. I've only used Bridgelux. If you know its full 17-digit (maybe 18-digit) code for the device, it will tell you exactly how it is set up. (That will be a Bridgelux code, there are many other manufacturers of 5050 stuff but the basic info is still good.)

It's nominally a 5V or 6V component, but is typically available on substrates of x units in series with y units in parallel. So that would determine whether it presents as a 6V or, say, 36V device.

OK, quick dig shows this code:
BXEP–30E–1C5–36 B–00–00–0

1C5-36 is 1 die in parallel, C in series, 5 is the power output (4.5W), 36 is the forward voltage.
425-06 is 4 dies in parallel, 2 in series, 5=4.5W, 6V forward voltage.

E&OE: this is largely from memory with a quick look at some old stuff I did.

(Edit: So I could have just provided this link: https://sirs-e.com/general/5050-led-datasheet/. This all seems to be 12V stuff with one 5V item)
 
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Bushcat

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And as an electronics bod, you know the higher the supply voltage, the lower the supply current, the thinner the required wiring, and less power lost as heat. If you're feeding from a standard/old-fashioned USB supply, that's 2.4A into 5V gives you around 12W to play with. Standard USB cable spec states 3A max, so a random power supply would give you 18W at 5V. Anyway, that would roughly tell you the max length of strip you could reasonably power (although most of these specs are based on feeding the strip at both ends).

At 36V, you could deliver the same power at 1/6 the current, so the losses from the secondary side of the power wart down to the strip would be 1/36th as much.

Most of this is irrelevant, though, if you're buying a finished device. In general, volts are good. The specs will tell you if you're actually buying a brighter unit. I'd probably just pick the brightness and color temp I wanted (in your case, UV), and the volts will take care of themselves: photon cannon 36V, fart in the dark 6V.
 

koraks

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Bushcat said:
The specs will tell you if you're actually buying a brighter unit.
Click to expand...

Provided the specs are any good, which isn't always the case. Extreme example here: https://tinker.koraks.nl/photography/what-a-300w-uv-floodlight-is-not/ Unit advertised as 300W is actually 75W.

Calvin Grier has been very vocal against UV LED strips and prefers COB LEDs because one can fit a lens over them and then use them at a larger distance for massively better collimation. However, that's very sensible for his way of working and it won't make all that much of a difference for stuff like cyanotype, where strips will work just fine.

I prefer the kind of floodlights I discuss at the linked blog post above because they're ready to go, don't require additional power supplies and are fairly cheap on a per-Watt basis. They mostly come wiht 400nm UV LEDs instead of 365nm, but that's absolutely fine (and actually very efficient) for virtually all alt. processes with the express exception of carbon transfer with DAS sensitizer (dichromate works fine on 400nm though).

bryans_tx said:
I see the SMD5050 highly suggested.
Click to expand...

Not very relevant IMO. I've done a lot of work on comparing LED options of various kinds and running the numbers. What you want in the end is decent power output at acceptable costs. Doesn't really matter what kind of form factor that comes in; it may be a mass of low-power 3535 components or a single 100W COB LED depending on what's attractive at the moment of purchase. Currently the market tends towards the former: large arrays of relatively weak/small beads. Higher power densities may be necessary if the application calls for it, but I find that a cheap array of many small emitters is fine for virtually all alt. process printing - hence my preference for the floodlight types I mentioned.

Things change when collimation becomes important, i.e. working with alt. processes that have thick layers (gum bichromate, carbon transfer, photogravure/photopolymer intaglio) and you're using screen negatives so need to image tiny dots very accurately (reducing dot gain). Then you really need something that is as collimated as it gets, which in practice means high-power COB LEDs at large distances of several feet. Strips are out of the question in that scenario.
 
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bryans_tx

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wow this is great info. I do want to be able use my new printers ability to 17x22 for the digital negative. And Gum Oil is on my must learn and do list.

Look forward to responding more this evening.
 

koraks

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bryans_tx said:
And Gum Oil is on my must learn and do list.
Click to expand...

Dichromate responds fine to 400nm UV light (contrary to what some people say) so generic 400nm UV LEDs will do fine.

Some people find that exposure efficiency is higher with lower wavelength, but this comes at the cost of much lower electrical efficiency of the LEDs and higher costs, and as a result, the optimum is still at 400nm as long as the process works with it. Not just my finding but also Calvin Grier's conclusion of side by side testing of various LED wavelengths specifically with gum bichromate.
 

gavinlyons

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I build my own and made a YT video and article about it. I think it should help you. I've used it for VDB and Cyanotype.

Build UV LED Box for Cyanotypes - Gavin Lyons Photography

In this video and blog we going to make a Cyanotype image with UV LED box. Normally Cyanotype are traditionally developed in sunlight. The print are often called sun prints. But it is winter and it is cold! The UV light isn’t so strong and readily available as within the summer. Wouldn’t be...
gavinlyons.photography

 
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bryans_tx

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Bushcat, yes I agree totally on higher voltage for less current. Dang I2R!
Gavin, I have actually watched your video several times
However the only potential wrong-purchase - is that I am in the States. A drab area of one at that lol! so the buy it source hmm..

Koraks, you have an interesting website, and I will have to poke around !

I have also recently watched several videos from Anna Ostanina.
Appears she also uses the floodlight (multiple, at angles) approach in quite an open area. Mounted quite high. Interesting.

the 17x22 size thing.. well I spent the extra $$ on a Epson P900 just for that. So by gum (oh a pun) I intend to use it...even though I will need a loan for the transparency paper... I wont even talk about when I need Ink ...
But it will be 8x10 or 5x7 for some time, as I still have several packs of Pictorio.

What should I need to know about distance from the lights to the contact frame ? I assume there is a accepted, typical working range.

Many of the Alt processes are well above my ability or patience, and a good reason is I am simply Art deficient. So multi color Gum Bichromate... hmmm I dont know.. besides there is so much to learn given any one type of printing

FWIW, the box I used to have used tubes. I did see a video of (i forget who, but was impressed by the skills) who pushes a Tube type setup. he uses 17 of them...135 dollars worth lol. I'll try and find the video, while sipping a Whiskey later

Bushcat, I am not having much luck at digikey.. amazon is most likely where I may end up. Not much luck at Bridgelux site as well, no UV showing up.

Well no rush, It's shaping up to be a lean month for photo $$ lol.

thanks so much for helping me out!
 

Bushcat

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>Not much luck at Bridgelux site as well,
Sorry, maybe I was unclear. Bridgelux is the ONLY company I have experience with, and could quote how its parts naming system works. I've not checked their product range beyond what I used, and I've no idea whether it has UV products. I don't even know if it's a good company. It's just the one I used. Luminus might be good for UV.

Also, now that Covid is fading from public conciousness, there's a lot of cheap, slightly used UV sterilizing gear out there if you're thinking of repurposing stuff.
 

koraks

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Bushcat said:
slightly used UV sterilizing gear out there if you're thinking of repurposing stuff.
Click to expand...

If that equipment actually does what it's supposed to do, it'll have a UV-C source. Don't use that for printmaking! It's very inefficient since most of the light will be blocked by the film and contact frame glass, and it's seriously harmful to boot.

For alt-print processes we use UV-A down to around 365nm mostly. At these wavelengths no sterilization occurs. Of course, there may be manufacturers of UV-A equipment that tout sterilization functionality that in reality doesn't occur. Such equipment may or may not be usable.
 

koraks

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bryans_tx said:
it...even though I will need a loan for the transparency paper...
Click to expand...

Try generic screen printing film. It's very affordable and comes quite close to the same quality as Fixxons. It's a tip @Andrew O'Neill gave me some time ago and it works very well indeed! It'll do fine for gum printing.


bryans_tx said:
Well, Mr. Koraks, you have enlightened me on UV TUBES lol!
Dang but you and your fellow ALT'rs are smart
Click to expand...

LOL! Thanks Smart - I dunno about that. Stubborn and somewhat irrational, absolutely
 

Andrew O'Neill

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It does very well for Carbon Transfer, Cyanotypes, and Kallitype, too!
 
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bryans_tx

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Oh cool… I can repurpose an old dresser drawer to use as the box.
And somewhere I may still have some various and sundry sheets of aluminum as a heatsink backing. Along with a few fans scrounged over the years!
I can use my lab supply I guess, it’s capable of 5 amps at 12v.
Heck I use it to charge the car battery a few times.
This is all very good!
I have an honest to goodness photography wooden contact frame for 5x7, and a print file brand “proofer” for 8x10
The plan is coming together!
 

MattKing

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bryans_tx said:
Oh cool… I can repurpose an old dresser drawer to use as the box.
Click to expand...

If you install the strips into the top inner surface of the dresser, you could use the drawer to hold the contact frame - just slide it under the light.
 
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bryans_tx

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I was thinking of just using the drawer, upside down. The dresser is a hunk o junk. lol
It may not present the LEDS to Paper at a "best overall" height. Maybe to close. not sure. I have to read up on that.
I do have a few logistics to work out.
 

Rolleiflexible

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There is an easier way. You can buy a pair of 96w UV LED Onforu fixtures for about $60. Mount them side by side and you have an 11x15-inch light. Doubled, 15x22 inches for $125.

I have been using them with a vacuum frame for Kallitypes and my exposure time is 22 seconds. I just bought four more so I can print 22x30 sheets. I can’t say enough good things about these lamps — well-built, reliable, cheap, powerful.

Onforu 96W LED Black Light Bar CT12

Shop Best Powerful 96W Blacklight Light Bar with 96 units high quality LEDs. Perfect for body paint, fluorescent poster, Halloween, Christmas, club, or party.
onforuleds.com
 
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