Light bulb help

eligius1427 - Friday, May 23, 2008 - 12:39pm

Hi all,

I'm working on a lighting/chandelier concept and would like your input on light sources. The lights will be fabricated out of aluminum tubing and sheet metal, probably with some sort of patina. The lights will be very organic and instead of using the principles of transparency, like that of crystals in a chandelier, it will use the principles of reflection, thus some of the lights will be focuses into the metal. I'm considering candelabra incandescents and/or halogen(two pin) for the main light source and small LEDs or fiber optics for ambient accent light. I like the warm light of incandescents, but it has the largest base. I'm concerned about the heat from the halogen, it will be in close proximity to the aluminum(roughly 1/4-1/2") in some places. Will that heat dissipate quickly since it's aluminum or will i have to worry about the fixtures/wiring/tape/patina ect. The LEDs or fibre optics will only be used to provide soft glows, pinpoints, and such accents. I'm choosing LEDS/fibre so I can get light through very small tubing and into hard to reach spaces. The white light from LED is two white/blue in my opinion to provide the main light. The lights will have space for transformers and such, so that's not an issue. All wiring will be inside the tubes, and the fixtures will need to fit inside an aluminum tube housing that will be specifically designed around the fixture.

Any advice or experience you have with this sort of thing would be greatly appreciated.

thanks

Jake

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Tough challenge. The heat

R L Sidebottom - Friday, May 23, 2008 - 1:04pm

Tough challenge. The heat from the Halogen might hurt the patina. Incandescents also have a heat issue, but at a much lower temperature. There may some compact florescent bulb available that might work.

The halogen might work if it is not directly aimed a crucial point where changing of the patina will be a big issue. Most of there heat is directed in the direction of the reflector.

Good luck

Rick Sidebottom
Aspiring Metal Artist

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Jake, I've been wrestling

Rich Waugh - Friday, May 23, 2008 - 2:11pm

Jake,

I've been wrestling with the same issues for a while now and have come to some fews little understandings that I'll happily pass along for what they might be worth.

You're correct about the light colors. LEDs are very cold, but small enough that in some cases you an combine white and amber to get a warmer color. Biggest issue I have with LEDs is that they are tightly directional. To get a wide dispersion requires either a lens or multiple emitters. No way around it. Some of the higher wattage LEDs come with a "lens" molded on. Keep in mind that until you get to the really high-wattage LEDs, (say 3-watt), you can use colored gels in front of them to shift colors. Photography supply houses and theatrical supply places carry the colored gels. I haven't tried it yet, but I'll bet you could dip them in plastic dye, too. It's a thought.

Halogens are hot, yes. They are also sort of a cold light color. You can offset some of both these issues by dropping their supply voltage a bit. Current-limiting resistor, series-wired load, etc. Maybe try a wave-clipper type of dimmer - the SCR type. The aluminum will dissipate heat pretty darn well, particularly if it is a darker color and a matte surface. Think of semiconductor heat-sinks and maybe design with some extra radiating area around the lamp base. Thermally-conductive paste such as used for mounting heat sinks on computer CPUs would increase transfer rates, too. You can calculate the heat transfer and loss rates if you know all the math. I don't, so I just experiment until I get what I need. Remember that heat rises and creates convection currents and use that to your advantage.

It's getting damn tough to find the high-quality candelabra sockets anymore. I'm talking about the ceramic ones, instead of the cheesy plastic and aluminum ones that crap out in a year in my maritime environment. DeSherbinin used to carry them, but doesn't seem to anymore. Maybe try MSC.
Incandescents are easy to dim, again using a wave-clipper, and you can use higher wattage bulbs then dim them to get a warmer light and much longer (triple or more) life. That's a plus in a chandelier where changing them is a bite in the butt.

Try to find silicone-insulated wire. It stands the heat far better than PVC, and is way easier to pull through tight tubing. Stranded is more flexible, but carries a bit less current for a given gauge. Be sure you follow accepted practices for color-coding, grounding, isolation and current loading.

Find out first if you're going to be subject to UL-approval requirements - it can cost as much as a grand to get a light UL-approved, if you can even find a shop within reach that can do it. I won't get into what you can do with a scanner and color laser printer and a bit of clear Mylar...

I hope this is some help to you. Let me know what you discover, too. I'm always eager to learn new things about lighting.

Rich

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I did some research on LEDs

QuiQue - Saturday, May 24, 2008 - 12:05am

I did some research on LEDs when I made the Marsi Chandelier. I found a UK based business named LiteWave.co.uk that has some cool products. What I decided to use is their CoolFusion LED projector along with an 80 tail fiber optic loom. What this configuration did, was to give the client the ability to have any color within the light spectrum shown on their chandelier. By adding a controller, they even have the ability to have the colors change with music!

I just put up a post here at ArtMetal which shows a video of the assembly of the chandelier. The Marsi Chandelier Part 3 will show you how I went about incorporating LED lights along with standard 110 volt lights. Electrical wiring is tricky, but can be very satisfying.

Good luck with your lighting commission!

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