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New York City Street Lights To Go LED
eldavojohn writes "Wired has a short piece on NYC's new street light project. I don't think we need to belabor the many benefits that LEDs hold over traditional light bulbs, but the finishing touches are being addressed, and they will hopefully be put into place sometime next year. This design won a competition back in 2004, and OVI has been whittling down the prototypes. At $1.175 million, this sounds like a pretty cheap deal considering the DOE forked over $21 million to 13 R&D projects along the same lines."
The thing that is awful about led lamps is that most of them are run straight off the AC voltage and have massive 100% brightness flickers. If you are moving it's like a strobe. You don't see it in car lights since they are run off DC. but most, perhaps not all, AC socket lamps I've seen have really bad flicker.
I also how they have secondary lenses since LED's can be very directional the way they are typically resin cast.
Some drink at the fountain of knowledge. Others just gargle.
many NewYorkers does it take now to change a light bulb?
FTA, the ~$1million is for building and testing six working prototypes. The design will then be added to a catalog the city uses, and they can then install them as they see appropriate.
I'll never make that mistake again, reading the experts' opinions. - Feynman
Yeah. I've noticed that. What I don't get is why they choose to set the color temperature that way. Red LEDs are extremely cheap compared with producing light at the other end of the spectrum. Why in the world would they balance them towards the blue (expensive) end of the spectrum when that is both more expensive and visually unpleasant? About the only thing I can imagine about the current LED designs is that they were designed to be used in combination with standard incandescent bulbs. If you blend the two, you should get a fairly nice looking light spectrum, albeit probably a bit heavy in the yellows....
I'd buy LED lights instantly if they actually used three emitters. Unfortunately, most don't. They use two---one yellow, one blue. Because the yellow LED has a relatively narrow light spectrum compared with an incandescent, you end up with basically no light output down near the bottom of the visual spectrum. The result is light that is downright unpleasant to deal with in every way. The bluish light makes it hard to see color accurately, makes colors not reproduce well in photography or video, and really isn't good for you mood-wise. Basically, the current crop of LED lights have all the problems of CFLs except the mercury (well, and the LEDs should last a lot longer, I believe).
The question, then, becomes this: "When are we going to see properly designed white LED bulbs?"
On the other hand, while they suck for homes, the existing LED lights are perfect for street lights. First, there was one experiment that suggests that suicides and crime may decrease when street lights are replaced with bluish lighting. Second, the color temperature of blue LEDs are virtually indistinguishable from the mercury vapor lights (~6000K) that are already used in a lot of places.
Check out my sci-fi/humor trilogy at PatriotsBooks.
Some of the newer LEDs can go above 100 lumens/watt.
One thing about HPS is that it spreads light everywhere, whereas LEDs are more directed, which you want in a streetlight facing down. Omnidirectionalness can be fixed with good fixture design, but most cities use crummy fixtures.
Not a typewriter
Here in Portland, OR, we have already started to use LED street lights. And now that we're in a snow storm, these lights aren't working. LEDs don't produce heat (that's why they're efficient). By not producing heat, they don't melt the snow away from them. So all the LED streetlights in Portland are covered in snow and cannot be seen.
The old lights produce enough heat to melt all the snow. Snow in Portland is rare, so it's not that big of a deal. In NY, it's quite the opposite.
Actually, LEDs get dimmer as they get used. If they don't fail due to the semiconductor turning into molten metal, they get dimmer and dimmer and dimmer. The 100,000 hour lifetime figure on LEDs is usually the time until 50% brightness (considered to be the point where one would notice the light being dimmer).
There are many reasons for this - degradation of the junction itself, but the semiconductor itself leads to a large index of refraction - a lot of the light in a LED gets reflected back into the semiconductor. And then there's degradation of the epoxy used to seal the LED. All these conspire to make the LEDs much dimmer, and get dimmer over time.
Why can't they make a single led the size of a lightbulb instead of 100 small led's.
Is it possible to make a single, huge led?
I don't know. Maybe it's the same reason that they can't make a tungsten filament the size of a whole light bulb. Instead, they keep selling us a tiny wire the size of a pubic hair surrounded by a huge void filled with argon gas. This has been going on for well over a century, and they never seem to fix it.
[...] Instead, they keep selling us a tiny wire the size of a pubic hair [...]
Please adopt the metric system. PLEASE!!!
[...] Instead, they keep selling us a tiny wire the size of a pubic hair [...]
Please adopt the metric system. PLEASE!!!
Pray tell, can you enlighten us to what the metric equivalent of a pubic hair is?
5.3 centicurlies?
Putting moderation advice in your
The flicker is not in his head, it's in the taillights. I've seen the flicker, it's caused by a pulse width modulation circuit to make the taillight mode of a combination taillight/stoplight appear dimmer. A quick google search pulls up this article http://findarticles.com/p/articles/mi_m0EIN/is_2006_Nov_8/ai_n27039046 about an automotive product specifically designed to address this issue and stop the flicker by eliminating the pwm circuit. It works by reducing the DC drive to the LEDs in taillight mode instead of using pulse width modulation to reduce the average current and effective brightness.