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White LEDs for a Brighter World
deepfry writes "CBC radio today featured an interview with Dr. Dave Irvine-Halliday, an engineering professor at the University of Calgary, who's developed a home lighting system for the developing world using a combination of white LEDs, pedal generators and rechargable batteries. This type of "pico-power" can make a huge difference in the lives of villagers in rural areas where being connected to a power grid is not an option and probably never will be. Read about the Light Up the World project and make a donation."
Why limit something like this to the developing world? If the developed world used low-power, high-efficiency lighting, we'd dramatically reduce the consumption of energy and non-renewable resources. If these lights are cheap enough for the poorest on the planet to consider using them, there's no doubt that they'd save the industrialized nations amazing amounts of money, as well.
Frankly, I suspect we'd do more for the developing world by adopting this sort of thing for ourselves--which is not to say, of course, that we shouldn't encourage them to skip our wasteful ways in favor of the right way to do things.
b&
All but God can prove this sentence true.
One way to bring down the cost would be to sell them in the developed world. A finished product, that could screw into a standard light socket, but use 1/100th the power to provide the same light would sell well in the U.S.
Especially with all the noise about power shortages and rolling blackouts.
Selling them in the U.S. and the rest of the developed world would go a long way towards creating enough demand for serious mass production.
Learning HOW to think is more important than learning WHAT to think.
About a year ago, I got a kitsch keychain from a vendor who was trying to sell software to my company. We didn't purchase the software, but I have held onto that keychain.
Let me describe it. It's oval in shape, about 3cm long by about 2cm across and 1 cm thick. Inside the body of the keychain, which is clear vinyl, you can see the mechanism that makes it so neat, which is a small watch-type battery, a very small resistor, and one of the newer white LED's. The clear plastic vinyl is red, so when you squeze the thing, it's light is very slightly pink.
Now, here's the thing that makes me keep this around. This little piece of what I would othewise call 'crap' is brighter than my 'keychain-size' Mag Light! I can easily read by or do computer maintenance with this toy. If I had five or six of them, I could reasonably light a room for however long the batteries lasted.
White LED's are the wave of the future, IMHO. They're cheap in terms of production and electricity cost. I also understand that they're significantly easier on the environment than incandescent bulbs or flourescent tubes. Unless you overload it with current, which I understand is very difficult since many come with tiny regulators in the form of attached IC's, they don't burn out, making replacement costs plummet.
Make my next lightbulb a white LED
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uh, ok. $1 a piece for a .1 watt bulb. sounds great. Exactly how many would I have to gang to be able to read my newspaper?
Maybe not that many... Remember that the efficiency of a normal light bulb is very very bad, since most of its energy is dissipated as heat. I wouldn't be suprised if a 100W bulb only produced 1W of visible light.
Opus: the Swiss army knife of audio codec
You should stop being so paternalistic and conservative. The attitude of your response shows you romanticize poverty, and mistake powerlessness for aestheticism.
This was also featured on Talk of the Nation on NPR last week. It is worth a listen.
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Oh bother.
What you do not realize, judging by your post, is that the average 20 mA white LED looks brighter than the average 40W 120V bulb. A single one makes an excellent flashlight. A few of them together make an awesome lightsource.
Our village elders agree with you. I'd say more, but we're on a hunt for witches and evil spirits right now, and the others tend to get suspicious if I don't join in...
Lately democracy seems to be based on the skybox, the Happy Meal box, the X-box, and the idiot box.
I work in the lighting industry with conventional means of producing light (florescent, incandescent, etc) and have done some testing on LEDs. The most important thing to realize is that the light being produced is not a pure "white" light.
Typically the manufacturer will use a blue LED and coat the outside of the lens with a yellow broadband phosphor, which when the blue light is filtered through it, appears white. True white is extremely difficult (and expensive) to produce; it's still years away and it has to do with the ability of the diodes to produce certain wavelengths of light.
As far as efficiency, yes, LEDs are quite effecient at producing light at a given (low) wattage but they are still not as bright as conventional light sources. The rating of an LEDs efficiency is measured in lumens per watt; a bulb with a higher lumen per watt rating is more efficient than that of a lower one. At this point, red LEDs are the most efficient, which is why many applications that use LEDs (exit signs, car turn signals, etc) are red.
Manufacurers claim a 100,000 hour life span of LEDs. What most of them fail to mention is that to acheive this, the power supply that the LEDs are attached to has to be set at a low current. Low current means decreased brightness. If the current is increased past the manufacurers recommended setting, you will get higher brightess but the lifespan will be cut short severely. Not to mention the fact that many LED applications where companies are touting 100,000 hour lifetimes (approximately 10 years) haven't been around that long to confirm or deny it.
LEDs are not going away, however. It's not a question of if they go mainstream, it's when. And I have no problem with that, it's just that from what I have observed, the manufacurers are dispensing half-truths and outright lies about this stuff. People take it for gospel because big companies are developing the technology (GE and HP-funded Agilent come to mind) so they figure it must be true.
Whatever. It's reall not going to make that much difference in the long run. Just want people to know there's more behind it.
The neutrality of this sig is disputed.
After hunting around for a reasonably-priced reading spotlight to mount in the minivan for my kids to read after dark, I couldn't find anything that was (1) bright and clear at low wattage (2) priced under $100US (3) small enough to hide in the trimwork. Then putzing around Radio Shack one day, I saw the rack of white LEDs, and decided to give them a whirl.
I bought 6 WLEDs for about $30, a couple 100-ohm resistors and 1K trimmer pots for current limiting and dimming, and went home. Half an hour and a few solder joints later, I had mounted the 6 LEDs shining thru holes in my overhead panel, pointed at my steering wheel area (hey, first I helped MYSELF, not the kids). I found that I could run three LEDs, with a voltage drop of about 3.5V each, in series with the fixed 100 ohm resistor and a trimmer pot. So two sets in parallel worked well. I couldn't wait until nighttime.
After dark, out to the van I went. Switch on - WOW.
First impression - the color was all wrong. Until I realized that I'm so used to yellow light that pure white was almost distracting. But the light was BRIGHT and very crisp. From about 18 inches from LEDs to reading material, with only 6 LEDs, I had more light than with the original dome light 20 inches away, and the color was perfect - I could enjoy reading material with photos, without straining to see the colors. The pool of light was about 15 inches across. The LEDs I used are rated at 30deg beam spread (to the point of half brightness) so that seemed about right for six lights pointed a bit apart from each other. Best of all, unlike a dome lamp, there was NO spillover light to the rest of the interior - with the light on I could still easily see out the front to drive. Don't try that for long with a glaring dome lamp.
One other thing was worth noting - there were faint yellow/blue bands in the pool of light, noticable only when looking at a large mostly blank page. This is probably due to the blue LED/yellow phosphor combination used to make white light.
The biggest problem was cost. At Radio Shack prices of $4.99 each, I couldn't affort enough LEDs to do the other five seating locations. But it was still far cheaper than a quality aircraft-style reading lamp, and just as bright. If I wanted more brightness, I can easily add more LEDs.
Check out this link - http://www.theledlight.com - for some really cool ideas, parts, kits, assembled lamps, all based on LED technology. Really cool, and a LOT cheaper for the bare LEDs than Radio Shack. About $2.50 or less each.
Soon I'm going to order some bulk WLEDs from them - and light up the rest of the vehicle interior.
--Brandon / Split Infinity Music