LED light panel

[macandal]

People make aquarium fixtures much like these all the time. Is this for color or bw?

Mostly B&W, but I'm not ruling out color.

[Peter De Smidt]

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.

[Eric Biggerstaff]

I used this video to create the LED UV panel for my UV box. There is another thread on that project in the forum.

[Jody_S]

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...

[Peter De Smidt]

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.)

[macandal]

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.

Jody, where do you find these? What's the brand?

[Jody_S]

Jody, where do you find these? What's the brand?

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

[Daniel Moore]

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 : ).

[Daniel Moore]

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.

[Pierre 2]

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.

I would really encourage people to stop and study electronic design and fabrication theory and methods before taking off with a project like that. Also think about how and where you are using them, and the related liability that comes with them. They're not a certified and approved device, and in the event of an accident the insurance agency is very likely to look at the remains, ask the make and model, and then smile and nod while closing their cheque book and walking away from you.


They are neat things that you can build with only a little investment, but waving away and ignoring risks involved is a good way to start fires or give someone a nasty shock.


Also consider general quality control and reliability. Really cheap LEDs that you can get a 'great deal on' from Ebay and such can be prone to high failure rates and wide specifications. I've seen more than a few people build similar panels and end up with uneven lighting across the field, which in turn ended up with dead LED cells bringing down the entire panel. Plus some suppliers tend to be a little liberal with their data sheets and specified outputs, so read up on a given supplier before buying, and be wary of deals that look too good to be true.

Building a very reliable, consistent, and robust product is not an easy or cheap task.

My best advice is to slow down, and don't rush a project like this. Take the time to understand how things work and why they get designed the way they do, and don't blindly follow really simple instructions off the web.