You Do It: Make Your Own Light Bulb

The stick welder provides enough juice to heat the tungsten to nearly 5,000Â°F, the ice bucket acts as the bulb, and the helium displaces oxygen from the bulb.

(Image credit: Mike Walker)

Editor's Note: This is one in an occasional series of articles from Popular Science's How2.0 department. The projects have varying degrees of difficulty depending on a project leader's experience, ranging from dabbler to master.

Dept.: Gray Matter

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Edison's first mistake was living before tungsten wire was available. Tungsten is way better than carbon as a filament material, and now you can find it in any metal-supply shop. It lasts longer, is less brittle, and glows with a cleaner, whiter light. His second mistake, repeated in classroom physics demonstrations to this day, was using a vacuum to get the air out of the bulb. Clearing out the air is important because at yellow to white heat (3,500°F to 5,000°F), pretty much all known materials, even tungsten filament wire, react with oxygen and burn up in a few seconds. Remove the oxygen, and the wire can't burn. But a vacuum is the hard way to solve that problem. You need an expensive vacuum pump, a thick glass bell jar to withstand the pressure of the surrounding atmosphere, and several nonleaking pipe joints.

For a filament, I used a thick tungsten wire I had lying around the shop and, for the power supply, a small stick welder I got at an auction. It supplied about 50 amps at 30 volts, giving me a 1,500-watt bulb. When I powered up the filament without the bucket in place, it produced a prodigious quantity of tungsten-oxide smoke and didn't last very long. But with the bucket on and a steady flow of helium, the filament glowed brightly and cleanly.