LED UV Light Box: Build Your Own for Under $150

[Eric Biggerstaff]

I have been wanting to upgrade my UV light source to something a bit larger and more powerful. The commercial made boxes are just to expensive to justify given the amount of alt process work I do and even used ones were more than I wanted to spend. The DIY boxes I saw were nice and I have several friends who have made them, but they seemed a bit complex and at around $500 that was even more than I could invest.

So, I set a goal of creating a good DIY UV box for under $150 if I could. Searching YouTube I ran across this video:

https://www.youtube.com/watch?v=jLia59KfkSw

This seemed like a good solution and not overly complicated, which is good as I am NOT an electrician or handy with tools.

I did a search for UV LED lights and came up with these:

http://www.amazon.com/gp/product/B00...f_rd_i=desktop

There are many others but these were powerful and affordable, I decided that I needed two rolls of them with each roll being 5 meters long.

Based on advise from a friend (who is active on this forum), we decided to use a simple power source and again use 2 so there is plenty of power for the number of light, I went with these:

http://www.amazon.com/Power-Adaptor-...G4SG1WJR2H1AY8

These provide plenty of power and are easy to work with, no need for fans or ballast as the LED's run cool.

Also, we adapted these to wire the lights to the power:

http://www.amazon.com/Connector-Sing...YN14J7DC1AP0VG

They are cheap so I bought a few but only needed two, one for each set of lights.

For the box, I simply used plywood I had on hand but if you were to purchase, I think you would maybe spend $20. Also, I bought a hinge and a knob for $12 total so my net investment in materials was around $100 not including tax and shipping.

So far so good.

Using the ideas shown in the video, my friend and i created the light panel. Ours was a little different but as you can see in the pics, it works just fine. I won't go into construction details as you can piece that together based on the video but one thing learned is that the LED's measure 3/8" of an inch wide so we spaced them 1/2" inch apart. This provides a very smooth even light and there is space between the strips that would allow me to add lights if I wanted to.

The entire build took about 8 hours total spread over 4 days, so not a big deal at all.

The LED's are attractive to use as they are cheap, no ballast required, have a 50,000 hour lifetime, run cool, and quickly light when the timer is tripped (mine have a 2 second lag so not bad).

Now, on to testing!

I will report on the results later this weekend.

Here are the pics:

[Eric Biggerstaff]

And a couple more:

[Peter De Smidt]

Looks good! Those led strips are certainly handy. How hot do they get? When I made my light source for my scanner, I used similar LED strips, but I mounted them to an aluminum heat sink.

[jp]

Looks good to me, testing results is what matters.

[Eric Biggerstaff]

A few more details, my light panel is 5.5 inches from the base of the box, when I place my printing frame into the unit, the neg rests about 4.5 inches from the lights as my contact frame is about an inch deep. Also, the inside of the box is painted white of course. The panel measures 17"x 22" which will allow print of around 16" X 20" if I ever get brave enough to go that large.

I just ran some tests and found that a palladium print on Arches will give me a min time / max black at 6 minutes. I used a piece of Pictorico as the film base as I print mainly digital negs with palladium.

This is not bad and is certainly a large improvement over what I was using, however I would like to knock another couple of minutes off of that time. To so, I could lower the lights closer to the neg or increase the number of lights. I may invest another $25 for an additional roll of lights to increase the total light output but for now, really, 6 minutes is pretty darn good.

A nice feature of this type of UV box is you can make them as large or as small as you like since the LED strips can be cut. They come in 5 meter rolls with a self adhesive backing so adding or removing lights is a breeze.

I will need to re-calibrate my negs now that I have a new light source, but that should not be too difficult.

[Michael Mutmansky]

This is not bad and is certainly a large improvement over what I was using, however I would like to knock another couple of minutes off of that time. To so, I could lower the lights closer to the neg or increase the number of lights. I may invest another $25 for an additional roll of lights to increase the total light output but for now, really, 6 minutes is pretty darn good.

I hadn't noticed this before, or I would have commented earlier...

Moving a light source that is a planar source (which this acts effectively as) will have very little impact on the exposure you get on the print within the reasonable distances you are thinking (up and down a few inches).

This is a result of the integrative math associated with a distributed light source and any given point on the paper. If you think if if this way, from any given point on the paper, there is a view of about 180 degrees in all directions. As you bring the light closer, the lights way out at the edges become less visible, and the lights in the center of field become stronger (closer) and the effect effectively cancels each other out (because there are a lot more out in the edges than in the middle).

Here is essentially the exact same effect as applied in electrical fields in a capacitor:

https://en.wikipedia.org/wiki/Capaci...el-plate_model

The key words in that write-up are "Assuming that the width of the plates is much greater than their separation d, the electric field near the centre of the device will be uniform with the magnitude E" and the formula does not have the distance between them as a variable.

However, there is a drawback to moving the light bank closer; the LEDs may have non-uniformity in their individual light beams (almost certainly, in fact), and you want a lot of overlap of the source beams to avoid being able to see the light beam patterns in the prints.

Here is a photo of a typical strip of LEDs (not the ones you specified, to be sure), and you can see that each individual one has a fairly narrow beam to it:

here

If I were planning to do an LED light box, I'd put the LED lights as close together as possible to overlap the sources as much as possible.

[sanking]

I agree with Michael that it would be best, in terms of short exposure, to space the LEDs as close as possible. That has certainly been my experience in building banks of BL tubes.

Now, what I would like to know is this. If we were to compare a bank of T8 Bl tubes, with appropriate ballast, spaced as closely as possible, with a bank of LEDs also spaced as closely as possible, which unit would put out more effective radiation for alternative processes like pt/pd? Is this something we could from the specifications, or would it be necessary to actually test this with a specific process?

Has anyone every made a direct comparison of this type?

Sandy

[Tin Can]

I like the neat agreement of empirical and calculation.

Thank you Sandy King and Williaty.

[Niall]

An interesting thread- lots of useful stuff here.

Somewhat belatedly, I discovered this thread part-way through construction of my own LED UV box.

I've got as far as cutting the strips and attaching them to the wooden panel, but am now alarmed about the prospect of their potentially short life-span.

Immediately, I'm struggling to solder wires to the copper terminals- it requires a degree of soldering finesse hitherto unknown to me.

Once/ if I get it connected, I'll post some pics / reviews about how it went and works.

Thanks to all,
Niall Bell.

[Eric Biggerstaff]

The heat output is very minimal, I left a bank on for 6 hours the other day and while there was a feeling of warmth, they were in no way hot. Even the power packs stay cool.