Interactive Hanging LED Array

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Contributors: Nick Poole
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72 Lightbulbs

Originally, the idea was that we would hang unaltered, incandescent light bulbs from the ceiling and control them using a bank of relays. A few experiments proved that this was easier said than done. The trick with an array of anything is that the effort necessary to get one piece working is multiplied into near impossibility. In this case, whatever it takes to get one light up and running will need to be repeated 72 times to complete the 6x12 grid.

There are a few major problems surrounding regular light bulbs. First of all, they are not terribly efficient, and the power requirement for lighting 72 bulbs at once (even at just 15 or 20 Watts a piece) can be daunting. Secondly, you get no brightness control, which limits the number of cool things that the installation can do. Finally, running that much high voltage line across the ceiling made us all nervous.

Eventually we settled on LEDs. They’re low voltage, relatively low power, and their brightness can be controlled with PWM. The only problem with LEDs is that they’re tiny, so they don’t look very interesting hanging from the ceiling and don’t have enough weight to hang plumb because the wire has a tendency to coil. We played with different ways of encasing LEDs in plastic and glue to make them more visually appealing, but we really wanted them to look like light bulbs. Our final decision was to hollow out 72 real light bulbs and replace their guts with LEDs.

many_hands_light_work

Light bulbs aren’t really meant to be taken apart once they’ve been put together, so it’s a little bit of a challenge to get into them. I enlisted the help of some coworkers, and we started pulling the ceramic insulators out of all of the bulbs, one box at a time. I didn’t break the envelope of the bulbs (the sealed part) because I hoped that the intact glass stem would help diffuse the LED light. Then I set about filling each bulb’s stem with hot glue and setting LEDs in place.

As I made my way through the boxes of bulbs, I tested each one with a coin cell battery to be sure the LEDs were good, then I put them back in their boxes and set those aside. My next task would be determining how to individually control 72 LEDs with as little headache as possible…