For BW it shouldn't be easy. For high quality color, well, that's another story. For color, you generally want 5000-5500K and a high CRI (Color Rendering Index). That's not all there's to it, as there's ways to fudge CRI, and it only accounts for a small number of colors. Cree and Nichia make fairly high CRI leds. Check out some sites such as: https://reefledlights.com/how-to-diy-led/ . Note that you'd use different LEDs than the aquarium people, who often want a lot of blue and uv.
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
I used this video to create the LED UV panel for my UV box. There is another thread on that project in the forum.
Before anyone goes ahead and builds this, you should know the current generation of 2x4' (ceiling tile, 'troffer') LED fixtures wholesale at @ $55 - 60. They go as high as 5,000K, and CRI is decent. I have an older generation 2x2' upstairs, I'm waiting for my wife to score another sample before I try them out as continuous lighting.
Or I could use it to power a DIY 11x14" enlarger head...
Building your own won't be cheaper, but you would have complete control over the parts. Cheap panels are, well, cheap. Ime, leds don't last anywhere near what is claimed. For instance, I had a $300 LED light strip, a Reefbrite, with high-bin Cree LEDs noticeably dim over about 2 years. I have a GE LEd bulb in the basement. It stopped working after about 3 months.
We use a cheap LED panel for some interior work. It's generally ok, but it's certainly deficient in the reds. (We use it to paint specific areas.)
“You often feel tired, not because you've done too much, but because you've done too little of what sparks a light in you.”
― Alexander Den Heijer, Nothing You Don't Already Know
Where do I find these? My wife works for the Canadian importer/wholesaler (these are one of her categories, so she's involved in the import, labeling and pricing). They're made in China or Korea, depending on who you buy them from. They're sold under any number of brand names, I couldn't tell you what names are common in the USA. My wife just informs me the $55 ones won't be on the market until October/November. Please remember the electrical distributor will add a 30% or so markup on these, + transportation costs.
I will be able to buy a small number of them at $55, but with shipping costs there is no way it would be economical to send these anywhere. My wife's company does sell some in the USA, you could try these people in the fall: Flynn & Reynolds
Tabor makes some sobering points. In one of my experiments I picked up some chinese 'high CRI' LEDs and upon first powering them up with the properly spec'd power supply several of them began releasing god knows what in the form of stench, smoke and heat. I pulled the plug and tossed them.
Peter D. and I have had much better luck so far with some RGB LEDs purchased from Lee Valley, the Armacost brand, which we use in our DSLR film scanners. They've held out over periodic use for me for more than a year, with no dead elements and no other surprises.
LED flicker has been an issue at higher shutter speeds with their PWM RGB control unit, beyond say 1/30th sec. Not sure what happens at much higher shutter speeds with their controller. I assume using them in a panel such as this is sized, would result in very significant shutter speed increases at normal working distances.
I'll look into the instructions/details for this project further and see what I can learn.
Macandal, I'm in Berkeley. Perhaps we could work together on such a project. Summer isn't a good projecty time of year for me though : ).
Correction, I did have two dead LEDs in the strip I purchased from Lee Valley. They sent me a 12" long strip to replace them for free and they've been doing fine.
Just on the liability issue : With no batteries involved, not sure that liability could ever be such a big issue : I believe that products operating on low voltage are typically not subject to certification. The power supply, yes as it is a "higher" voltage device. Stick with certified power supply and be sure get one for which the load capacity will exceed the actual load you will be using. A correctly rated fuse on the low voltage side remains a useful feature. Then, what remains are sound wiring (and heat sinking) practices (which may not be everyone's major strength...). Various recommandations obviously remains.
Pierre Leduc
Following link is just a recent sample, pending presentable Large Format production...
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