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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."
Assuming the line voltage is run through a full wave bridge rectifier, there would be a 120 Hz flicker, imperceptible to most people. Toss a large capacitor across that DC output and you've got dramatically less ripple.
true but then you also have 100 times the surge current when you turn them on, or a slow turn on.
What you say is of course obvious to any EE, and yet i've never actually seen a single 120v LED lamp made that way. One wonders why.
Some drink at the fountain of knowledge. Others just gargle.
Are there any major observatories near NYC? (hmm large mountains close to NYC?)
Are these new lights narrow or wide spectrum?
See: http://en.wikipedia.org/wiki/Light_pollution
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
These aren't headlights, they're street lamps. Do you really care if it takes them 3 minutes to warm up?
And even assuming they have ballasts featuring accelerated warm-up, the starting current will still be as much as double the normal operating current requirements. Really though, the starting current is negligible in the grand scheme of efficiency comparisons.
I'm not an expert on line voltage LED units designed to replace incandescents, but I would imagine including a bridge rectifier and capacitor would increase the cost and pose significant design constraints due to the components size.
You can't legislate goodness. Let each to his own destiny, by will of his freely made choices.
Just because you don't have some trait doesn't mean that other people don't. In this case, that trait is how fast your eyes can see. Congratulations, you have slower eyes.
I am one of those people. It isn't just "flicker", I can see the image-black-image-black pattern of the CRT at 60Hz without doing any tricks like waving my hand in front of the monitor or using the side of my vision.
I can't stand to be in the same room as a CRT monitor running at 60Hz, it is almost physically painful to see. When I had a CRT I had to run it at 85Hz to be able to use it for any period of time, but still had to make the text white on black, turn the brightness down, and such.
If it doesn't bother you, then imagine replacing every CRT with a strobe light running fast, as bright as the monitor. That would be annoying and distracting, right?
Imagine that tail lights of cars and buses were red strobe lights. Around here, that is actually a reality, with most of the new buses and some new cars having tail lights running at 60Hz. It is extremely obvious to me, where I can instantly point out which cars in a long line have blinking LED tail lights.
If I have nothing to hide, don't search me
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.
I don't know what I hate more on slashdot .... seeing somebody spout off when it's obvious to anybody with even passing familiarity in the field in question that they're full of it, or seeing somebody get shat upon when they ask a perfectly valid question in an attempt to try to learn something new