My new XP-E living room light.

[foxtrot824]

I have been toying with the idea of making light fixture with more than 3 LEDs for some time now. I seem to allow my flashlight budget to grow and grow and yet $40 for LEDs for a lamp seems crazy! I finally got around to getting this project rolling. I order 6 XP-E 5A Q3s from eprom for a nice neutral light. I had the joy of reflow soldering them to stars myself using the side of my soldering iron (I'm actually getting good at it). I decided that for this lamp I wanted a unique look and to hide the light source. I went to Lowes my one stop solution for a customer service free experience and picked up a piece of aluminum. about 2" wide by 36" long. Like most of my projects I visualize them first, maybe draw them out and then just start ordering parts. This one turned out as I had imagined. I wanted just a strip of aluminum hanging from the ceiling with the emitters facing up out of site. I used some Arctic Silver 2 part epoxy to mount the stars to the aluminum strip/fixture. Notice the excess epoxy, next time use BB sized portions NOT pea sized . I used an xitanium driver 350mA driver to run the 6 LEDs series. While not very scientific I have found the lamp to stay cool to the touch, maybe 80 degrees F. The power wires also act as the support and are routed through 2 holes drilled in the strip to prevent the wires from slipping. Notice the heat shrink tubing applied to the wires in this area to further prevent any shorting. All and all I am pleased with the color temperature of the light and appearance. The light hangs about 20" from the ceiling to get the most light to bounce off of it while making the LEDs not visible when looking at the light from another room.


Notice how the girlfriend's yoga mat makes an excellent work bench take care not to get any thermal epoxy on such mats while working on LED projects.

I used a measuring tape and permanent marker to mark the placement of the LEDs evenly.

I'll be sure to use BB sized portions next time.

This is what the lamp looked like all wired up and ready to be mounted. Tip: CLEARLY mark the polarity on the LEDs before soldering. This will save you the headache of re-soldering lights.

This is an up close shot of the LEDs running.

The final product!

It's hard to get an idea of how well this illuminates the room. I wouldn't say It's far brighter than a 60 watt incandescent but I like it more . While not the greatest comparison below are 2 pictures of the living room. The first is the LED and the second is a 60 watt incandescent lamp (the only one in the house, it doesn't get used very often)



Below is a shot of the light from the floor looking up.


Hope you all enjoy, as always I'm open to any questions or comments.

 

[blasterman]

While not very scientific I have found the lamp to stay cool to the touch, maybe 80 degrees F.

Don't cut yourself short. This type of design might seem too simple, but it will outlast most of the commercial options by basis of it's simplicity and no requirement for active cooling. Right now I have several of these exact bars growing houseplants, and the run at the same temp. I'm trying to find th right diffuser option for downfiring.

Suggestions: While themal epoxy works (I actually mix my own custom recipe that works MUCH better) I've found it simply more convenient to get some short, 1/8 bolts and drill through the bar. It's a bit more work, but at some time if you decide to upgrade LEDs it's a heck of a lot less messier.

 

[Ken_McE]

That last image keeps making me think of Larry Nivens "Ringworld", don't know why. Do you happen to know how many watts you have going in, and how many lumens coming out? Nice clean build.

 

[foxtrot824]

Do you happen to know how many watts you have going in, and how many lumens coming out? Nice clean build.

I am running 6 XP-Es in series at 350mA, approximately 1 watt a piece. Sprinkle on a few more watts for driver inefficiencies and I figure its drawing about 8-10 watts at the outlet. I am going to test that this week to get a solid number.

 

[eprom]

Good project foxtrot824. What you think to protect the led domes from dust?

 

[foxtrot824]

Good project foxtrot824. What you think to protect the led domes from dust?

A couple of other people have mentioned that as well, I'm not sure what kind of dust cover solution I'll use yet. I am open to any ideas though

 

[blasterman]

If they're glass domes, you shouldn't need a cover. Or, you can get some thin plexi sheets from Hobby Lobby, cut it to size, add some wood shims to the bar, and screw the pleix over the emitters an into the shim. Since it's not visible it only has to be functional.

However, I'm building more and more of these and getting fancier and fancier. Right now I'm adding a strip of wood to fit over the top, and drilling 1" holes in the wood to fit over the emitters. This way I can use an optic if I want.

 

[jeffosborne]

Very nice light, foxtrot824! Looks like you get a wonderful soft light. How far is the fixture from the ceiling? I have made a few household fixtures with common aluminum bars, and sometimes like to finish the 'viewing' side of the bar with a rotary brush or steel wool to get a brushed look. Anyhow, good work! Jeff O.

 

[foxtrot824]

Very nice light, foxtrot824! Looks like you get a wonderful soft light. How far is the fixture from the ceiling? I have made a few household fixtures with common aluminum bars, and sometimes like to finish the 'viewing' side of the bar with a rotary brush or steel wool to get a brushed look. Anyhow, good work! Jeff O.

Thanks.

The bar is about 20 inches from the ceiling. I have been thinking about at least painting the bar to put a finish on it. A brushed look would be very nice as well.

Also to those who were wondering I have measured the draw at the outlet using a watt meter. 8 watts! that's it! 8 watts after driver for ~558 emitter lumens

 

[Manzerick]

very nice set up!


I really like where these projects are going! Such an imporvement over CFL's!

 

[blasterman]

I just built a light-bar with a dozen older 1-watt Crees. Don't laugh, they have the best warm-white color with a hint of 'rosiness' I've seen. Plus, using a lot of dimmer LEDs spreads out the light and makes it less specular.

Oh yeah, you can't find these at Walmart. That's why they work good.

 

[curby]

While themal epoxy works (I actually mix my own custom recipe that works MUCH better) I've found it simply more convenient to get some short, 1/8 bolts and drill through the bar.

Just out of curiosity, what's your recipe? I think I'll probably just use the arctic alumina but if it's easy enough I might try reproducing your formula. =)

I like the ability to switch things out that way, but I'm concerned about the logistics. If the bolts are going straight into the aluminum, you probably want to pilot them somehow? If you're using nuts on the other side of the bar, then the mounting options get narrower as it'll be hard to flush-mount the bar with the nuts in the way.

 

[J_C]

I like the ability to switch things out that way, but I'm concerned about the logistics. If the bolts are going straight into the aluminum, you probably want to pilot them somehow? If you're using nuts on the other side of the bar, then the mounting options get narrower as it'll be hard to flush-mount the bar with the nuts in the way.

You can do it a few different ways to good effect.

1) Use aluminum bolts, drill undersized holes then use a tap-n-die set to tap the holes to the thread pitch of the bolts, these bolts being slightly longer than needed to extend past the bottom surface of the plate (intentionally for the next step...).

With the end of the bolt extending through, grind it down flush with the surface of the plate, then brush or sand the whole thing. Result if done well is a completely flush surface instead of the irregular end of a bolt, closely matching the plate sheen and color with only a minimal amount of circular pattern you won't see from a distance.

2) Use a plate thick enough you can counter-sink the nuts. If the plate isn't thick enough to use full (standard per their diameter) thickness nuts and completely countersink them, grind them down later or put them on a belt sander beforehand to decrease their thickness (but do so with bolts in them at the time to preserve the threading better).

3) Arctic Epoxy can be mixed to varying ratios with their regular thermal grease to make a semi-permanent but still removable bond. Make a test batch and use it on something non-valuable, a test case to see how hard your ratio makes it to later remove what you epoxied. I don't have a ratio recommendation as I have not done this myself but vaguely recall Arctic Silver once recommended this for their products when a non-permanent bond was desired. I think I would try 1:3 parts grease:epoxy as a starting point for testing.