3 ms·

Not so much; it's operating far under the level of light it could put out and at atrocious efficiency. As said in the article: "Modern bulbs, she explains, use

by coryrc 12y ago

Not so much; it's operating far under the level of light it could put out and at atrocious efficiency. As said in the article: "Modern bulbs, she explains, use thinner tungsten filaments that put out more light (40 to 200 watts) burn hotter, and are therefore taxed more rigorously than older bulbs like the Shelby" With semiconductors, the rule of thumb is an increase of 10 Kelvin halves the lifetime of the part. Considering this bulb is running several hundred Kelvin below modern bulbs, it isn't surprising it lasts. Run a modern 60W lightbulb at 30Vac and it'll last just as long too, but put out so little light as to be near useless (like this bulb).

femto 12y ago
Another common example is the light bulb behind a typical doorbell button. For example, the one on my parent's house is a 12V bulb, with the voltage turned down so it only produces a glimmer of light, enough to locate the button at night. It also runs continuously. So far it's clocked up 40 years and will probably outlast the structure of the brick wall it is attached to.
perrylaj 12y ago
You pretty much nailed it. I lived down the street from this lightbulb as a kid and never heard of it until it became a phenomenon on the web. It should be said that they intentionally run it dim in order to prevent burnout. Didn't read the full article, but I'm guessing they mentioned the lightbulb also has its own UPS to deal with power outages/surges. Unless I'm forgetting my P-Chem (possible, it wasn't a favorite subject), the 10 kelvin/halving lifetime loosely holds true for most chemical reactions that occur out of extremes -- e.g. that relationship holds true for most reactions that naturally occur on our planet. I still find that to be one of nature's neat factoids.
jloughry 12y ago
If you're at all interested in this topic, I can't recommend highly enough a little book by Tony Kordyban, Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong. (The sequel, More Hot Air, is good too). The author makes the case, in Chapter 30, that those numbers, which came from MIL-HDBK-217, were pulled out of somebody's hat at a time when semiconductor reliability rates were changing rapidly due to process improvements, and probably don't have much validity any more. When actual reliability rates were compared to prediction and measured temperatures, there was no correlation. These books are great. Refs: [1] Tony Kordyban. Hot Air Rises and Heat Sinks. New York: ASME Press, 1998. ISBN 0-7918-0074-1 [2] ---. More Hot Air. New York: The American Society of Mechanical Engineers, 2005. ISBN 0-7918-0223-X

by coryrc 12y ago

femto 12y ago

Another common example is the light bulb behind a typical doorbell button. For example, the one on my parent's house is a 12V bulb, with the voltage turned down so it only produces a glimmer of light, enough to locate the button at night. It also runs continuously. So far it's clocked up 40 years and will probably outlast the structure of the brick wall it is attached to.

perrylaj 12y ago

You pretty much nailed it. I lived down the street from this lightbulb as a kid and never heard of it until it became a phenomenon on the web. It should be said that they intentionally run it dim in order to prevent burnout. Didn't read the full article, but I'm guessing they mentioned the lightbulb also has its own UPS to deal with power outages/surges. Unless I'm forgetting my P-Chem (possible, it wasn't a favorite subject), the 10 kelvin/halving lifetime loosely holds true for most chemical reactions that occur out of extremes -- e.g. that relationship holds true for most reactions that naturally occur on our planet. I still find that to be one of nature's neat factoids.

jloughry 12y ago

If you're at all interested in this topic, I can't recommend highly enough a little book by Tony Kordyban, Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong. (The sequel, More Hot Air, is good too). The author makes the case, in Chapter 30, that those numbers, which came from MIL-HDBK-217, were pulled out of somebody's hat at a time when semiconductor reliability rates were changing rapidly due to process improvements, and probably don't have much validity any more. When actual reliability rates were compared to prediction and measured temperatures, there was no correlation. These books are great. Refs: [1] Tony Kordyban. Hot Air Rises and Heat Sinks. New York: ASME Press, 1998. ISBN 0-7918-0074-1 [2] ---. More Hot Air. New York: The American Society of Mechanical Engineers, 2005. ISBN 0-7918-0223-X