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Scientist hope to put LEDs to work in brilliant new ways

LEDs, light emitting diodes, are a very old invention, with the first visible-light diode being invented in 1962.  They consist of a junction of semiconducting material, such as a silicon or gallium compound.  However, scientists today are looking to teach this old dog some new tricks, and putting LEDs to work in a plethora of creative uses.

The magic is in the material.  While LEDs have been around for a long time, new and exotic materials are being used and older materials are being tweaked and reformulated to provide, a wider range of colors, brighter light, and higher efficiency.

The result is that LEDs may soon be permeating our lives in new ways.  LEDs are already invading the automobile headlight industry and are in high demand due to their superior life and brightness. 

Now one place scientists are looking to plant the LED is in the home.  Tungsten lightbulbs have a very low 5% efficiency, compared to modern LEDs, which have around a healthy 40% efficiency.  The result is power savings, increased brightness, and superior life.  Obstacles standing in the way of this development are the still higher cost of LEDs and the fact that LEDs' white light has much more blue than sunlight or natural bulbs.  However, these obstacles are fading as costs slowly drop and scientists develop better material blends to provide more yellow to the LED's emissions, making for a warm light that would be welcome in many a household.

Scientists are also looking to put tiny LEDs to a new use in the lab and eventually in commercial internet connections -- quantum cryptography.  Tiny streams of photons in the system would pass from the LED to the a detector.  Any interception of the beam (ie. snooping) would result in the signal being altered, as per the observer effect.  Such a system, when properly implemented would be in theory immune to any sort of malicious interception between the sender and the receiver.

Yet another use for the little lights has been proposed by scientists -- this one with promise of bringing new high-tech hope to impoverished regions.  One of the world's largest problems is the lack of clean drinking water in third-world nations.  Chemicals can be used to treat drinking water, but they are often expensive, toxic, and require a large amount of infrastructure.  A frequently used alternative is high-energy UV light known as "deep UV", emitted from special UV bulbs.  Passing a beam of this light through water kills most bacteria and destroys most viruses cleanly and simply.  The issue with this system is bulbs constantly need to be replaced and are two bulky for small scale use.

Scientists feel the answer is deep UV LEDs.  While they are still working on perfecting the materials, researchers,  such as Dr Rachel Oliver, an LED researcher from the University of Cambridge, think it is just a matter of time before the optimal combination of materials is found. 

"Deep-UV can't be made from the combination of materials we're used to, although I certainly think it's possible," Dr. Oliver stated.

Dr. Oliver is among many researchers striving to put LEDs to use in new and creative ways.  She sees LEDs being commercially implemented in the aforementioned uses within 10 to 20 years.

For now these prospects still remaining cost prohibitive and are dependent on material breakthroughs, but the future sure looks bright for these little devices.  And companies are looking to put LEDs today to a different and even more outlandish use -- clothing -- every airport security officer's worst nightmare

Whatever their form, LEDs are transforming the way we light and see our world.


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home light
By TMV192 on 12/15/2007 11:26:26 PM , Rating: 2
quote:
However, these obstacles are fading as costs slowly drop and scientists develop better material blends to provide more yellow to the LED's emissions, making for a warm light that would be welcome in many a household.


I personally don't like the "warm light", I bought a small cool white 24 LED light bulb and I found it much more pleasant on the eyes. Right now, the larger bulbs are too expensive, so I went with CFL. I use mostly 5000K and 4100K which is not too warm




RE: home light
By Ringold on 12/16/2007 12:25:21 AM , Rating: 5
I can't stand that sort of light myself. Similar reason why I don't go for CFL, except in some lamps that have yellow whatcha-call-'em around them, that provides a decent effect. The lag time to full brightness totally rules out certain applications, like stair wells, too.

No, they get some warm colored LED's that spread light over a wide angle and then I'll jump on this particular green bandwagon whole-heartedly. Low energy use, long life, and then good output quality -- no reason not to at that point.


RE: home light
By Bonesdad on 12/16/2007 12:29:14 AM , Rating: 2
in my experience, the lag time you mention doesn't really apply...true the CFL are dimmer when you flip them on...but not so dim you couldn't see going down the stairs.


RE: home light
By zsdersw on 12/16/2007 8:04:44 AM , Rating: 2
Time-to-full-brightness is also not something *all* CFL's suffer from. I have some in my kitchen that are as bright when you flip the switch as they are after being on for 5 minutes or an hour.


RE: home light
By FITCamaro on 12/17/2007 1:27:10 PM , Rating: 2
Or you just wait 1 second for it to fully come on.

The only downside for some CFL bulbs if I recall is you can't use them with dimmer switches. But I don't have any of those anyway.


RE: home light
By blaster5k on 12/16/2007 10:25:57 AM , Rating: 3
The other problem with CFLs is that their lifespan is a function of how many times they are turned on and off as opposed to just how long they are used. Incandescent bulbs, despite their higher energy usage, are still a better solution for lights that go through rapid on/off cycles.

I don't think LEDs have this problem either, but I could be wrong.


RE: home light
By mindless1 on 12/16/2007 11:28:24 PM , Rating: 2
Compared to LEDs, even incandescent bulbs are terrible for rapid on/off cycle lifespan. There is no other light source I'm aware of that is even tolerant of 1/10th as much cycling as an LED. The problem with incandescents lies in high inrush current until the filament is heated.


RE: home light
By TomZ on 12/17/2007 3:10:07 PM , Rating: 2
Incandescent couldn't be all that bad for cycling. After all, they've been used for decades in traditional "cycling" applications like stoplights, railroad crossings, industrial indicators, automotive turn signals, etc. etc.


RE: home light
By mindless1 on 12/18/2007 4:27:08 AM , Rating: 4
In a world that wasn't concerned about efficiency, yes.

Today, to reach high efficiency it means using switching supplies with high frequency pulses of power.

That is, if one uses LEDs. Consider that for stoplights, many have already been replaced because their failure rates at the on/off duty cycle were costing more than the investment in LEDs to replace them.

How bad they are is just relative, even a turn signal goes through a mere few dozen thousand cycles while an LED can tolerate than in one single day, and keep running for a few dozen years if all the supporting infrastructure remains viable.

LEDs have no equal in cycling. the only problem is when penny pinchers or foolish designers try to overdrive them to conserve space, or construction costs of lighting fixtures. Overdrive an LED enough and the energy savings wasn't of much importance, relatively, compared to energy to replace it and that cost, but as with all industries there is enough interest that the body of knowledge will soon enough allow even average joe customers to ask the hard questions about how the specs were achieved and demand a standardization beyond the discrete part output, rather specs about the achieved performance as implemented in the particular device.

I suspect even railroad crossing lights are being replaced by LEDs when the local budget allows, but on the other hand it wouldn't make much sense to do so until the stockpile of old incandescent bulbs were used up.


RE: home light
By mindless1 on 12/16/2007 11:33:30 PM , Rating: 2
I wonder if you are only considering one sample or bulbs of yesteryear. There are a reasonable number of CCFL bulbs today that produce a reasonable hue and while they may not be at a perfect hue or 100% brightness immediately after being turned on, they are reasonably near that within a second or two, are certainly suitable for a stair well or wherever, except outside as most are not designed to withstand extremes of hot or cold, or water for that matter.


RE: home light
By masher2 (blog) on 12/17/2007 2:01:03 AM , Rating: 2
Color rendition and startup time has certainly improved on CFL bulbs, but they still have other issues. Some people (my wife among them) are very sensitive to the flicker effects. CFL bulbs also put out a fair amount of ultraviolet, which can cause problems for those sensitive to it.


RE: home light
By SandmanWN on 12/19/2007 10:26:38 AM , Rating: 2
Yet on the flip side I personally enjoy the slow up time of CFL especially in the morning when waking up. It doesn't seem to hurt my eyes nearly as much as the instant on effect with incandescents.

What is a fair amount of ultraviolet anyway? Is it anywhere near what your eye takes in typically from just being outside? If its not, then that isn't much of an argument, especially with the few people it actually affects and the alternative light sources available.


RE: home light
By timmiser on 12/16/2007 12:38:08 AM , Rating: 2
I agree with you. I'm a big fan of true white light that much more closely resembles natural sunlight. I have long ago replaced all my inhouse bulbs to CFLs and have been enjoying the energy savings.

> 60w of light for 13w


RE: home light
By Lazarus Dark on 12/16/2007 2:21:05 AM , Rating: 2
I was about to say the same thing. I hate yellowish light. It hurts my eyes after long periods. I much prefer blue to white light. When I build my own house, it will definately use all led lighting.


RE: home light
By Haven Bartton on 12/17/2007 3:29:30 PM , Rating: 2
I've never quite understood this myself. As I was taught, sunlight is far "bluer" than our normal indoor lighting. Isn't is the difference of 5400K and 7200K? We went over this in film school, but I can't recall the exact numbers.

Shouldn't these LEDs just be better mimicking sunlight?


RE: home light
By masher2 (blog) on 12/18/2007 3:32:32 PM , Rating: 2
The issue with LED's isn't the amount of "blueness", but rather the fact that "white" LEDs don't really emit white light at all. The most common sort use phosphors to generate two different frequencies of monochromatic light, which our eye perceives as white. Despite that, the light is deficient in all the other frequencies, which typically makes for poor lighting.


RE: home light
By mindless1 on 12/23/2007 10:24:50 PM , Rating: 2
LEDs come in different color temp even for the same "white" part. The highest efficiency tend to be a more blue color, since blue is the actual light produced then (usually) a yellowish phosphrous coating converts to other spectrum. The conversion isn't 100% efficient so the further from blue it drifts, the more light is lost.


Don't forget...
By Spartan Niner on 12/15/2007 11:21:46 PM , Rating: 4
quote:
Tungsten lightbulbs have a very low 5% efficiency, compared to modern LEDs, which have around a healthy 40% efficiency. The result is power savings, increased brightness, and superior life.


... and a direct result of the higher efficiency and lower power draw is that it produces less heat ! Quite important to those of us who live in warmer climates :)




RE: Don't forget...
By timmiser on 12/16/2007 12:40:22 AM , Rating: 2
That is important too. So does anybody know how this percent efficiency scale works? What would be 100% efficient?


RE: Don't forget...
By lumbergeek on 12/16/2007 2:04:05 AM , Rating: 3
100% efficiency would mean 100% of the energy input would be converted to photons - zero heat or other by-product radiations.


RE: Don't forget...
By CubicleDilbert on 12/16/2007 7:07:58 AM , Rating: 3
LED efficieny is always 100% due to recombination of electrons and their counterpart (positive holes).
The problem is, however, that most photons are immediately absorbed by the surrounding material, which results in heat.
At Osram in Germany, they only recently invented a mirror like material which can reflect and direct the released photons out from the material into the plastic diffusor. (Check their press material).
I assume, this would allow for the very first time to have some real powerful LEDs.
So far, all LED lamps have really dissappointed me because their effective lumen intensity is piss poor.


RE: Don't forget...
By masher2 (blog) on 12/16/2007 12:23:55 PM , Rating: 4
> "100% efficiency would mean 100% of the energy input would be converted to photons - zero heat or other by-product radiations. "

No. 100% efficiency means not only that all the input is converted to photons, but what portion of that spectrum is visible to human eyesight. Incandescent bulbs convert nearly all their input to photons...but most of the photons are in the infrared range, which makes for a very low luminous efficacy.

Interestingly enough, a 100% efficient light source isn't possible with "white" light. Such a source would be monochromatic at 555 nm (a bright green).


RE: Don't forget...
By Souka on 12/16/2007 10:25:00 PM , Rating: 2
and what is effeciency of CFL?

(assuming all bulbs put out equal light, at similar quality...what is effeciany comapred to the 60w incandecent?)

60w incadencet bulb = 5% effeciency
60w equavlent LED bulb = 40% effeciency
60w equavlent CFL bulb = ?


RE: Don't forget...
By masher2 (blog) on 12/17/2007 1:58:07 AM , Rating: 2
I don't know where Jason got those figures, but the LED bulbs I've seen are less than 10% efficiency (though another poster in the thread has a link to some in the 15% range). Fluorescent "tube" lighting is about 15% as well, whereas the CFL bulbs with integrated balasts are generally about half that.

A 60w tungsten bulb is more along the lines of 2% efficient.


RE: Don't forget...
By Oregonian2 on 12/17/2007 3:34:46 PM , Rating: 2
And unless one has an IR LED, having light be non-visible isn't a problem most of the time AFAIK because most LEDs are roughly monochrome (not counting things like ones using phosphors or multiple die).


RE: Don't forget...
By akugami on 12/16/2007 2:30:16 AM , Rating: 3
Not just warmer climates, heat is a problem in many areas that require lighting as it would take extra cooling to dissipate the heat.

For one, server farms and data centers where there are a large amount of computer equipment running in very tight confines. There needs to be sufficient light to see by, especially when trying to look through a spaghetti web of wires. But the extra heat from lighting means more cooling is needed. Not only would leds save money from more efficient use of power, but it also produces less heat which means you save money again on cooling.

Grammar Police: The issue with this system is bulbs constantly need to be replaced and are two bulky for small scale use.

Should read "too" and not "two" I'm going to assume. :)


RE: Don't forget...
By mallums on 12/16/2007 8:05:09 AM , Rating: 1
LEDs are interesting, but the best efficiency to be had is from fluorescents. They are typically 90% efficient vs. 40% or so from the best LEDs. The main drawback is that they contain mercury. While there is much less mercury in newer bulbs, there is work to be done. Nevertheless, I believe that the future lies with fluorescent technology, not LED tech.


RE: Don't forget...
By zsdersw on 12/16/2007 8:11:47 AM , Rating: 3
Oh, I wouldn't be so quick to judge where the future is going to be. LED's limitations and drawbacks are not so insurmountable.


RE: Don't forget...
By masher2 (blog) on 12/16/2007 12:27:04 PM , Rating: 2
> "fluorescents are typically 90% efficient vs. 40% or so from the best LEDs"

No. The best fluorescents are in the 15% range. That's better than commercially available LED lighting (which runs up to 10%), but not as good as research-grade LEDs now being made in labs.


RE: Don't forget...
By codeThug on 12/16/2007 1:33:06 PM , Rating: 2
quote:
compared to modern LEDs, which have around a healthy 40%


Mash, The article mentions 40% for modern LEDs. I'm assuming this means "state of the shelf" not "start of the art". You mention commercial LED lighting being 10% efficient. I'm trying to understand the disparity here.

Is the Author talking monochromatic LEDs(40%) vs commercial lighting white LEDs(10%)? 10% seems fairly low even for white LEDs. Are there other losses involved in commercial LED lighting?


RE: Don't forget...
By masher2 (blog) on 12/16/2007 3:50:49 PM , Rating: 2
I won't speak for the author, but luminous efficiency is easy enough to calculate yourself. I looked up a page on LED light bulbs and took the first one which came up:

http://www.ccrane.com/lights/led-light-bulbs/index...

The best bulb on that page generates 150 lumens for 2.75 watts. That's an efficacy of 54 lm/W. Divide by 683 and you get an efficiency of around 8%.

Nichia here claims an efficacy of 3X that, but I don't believe these are on shelves yet:

http://www.nichia.co.jp/about_nichia/2006/2006_122...


RE: Don't forget...
By mindless1 on 12/16/2007 11:22:49 PM , Rating: 2
There are more efficient LEDs available today such as Cree XR-E series, a Q5 grade at 94 lm/W efficacy being available in quantity and soon the R-grades are expected in volume.

Focusing on Q5 as the contemporary offering, 94/683 = 14%

http://www.ledsmagazine.com/news/4/6/37/Creebins

http://www.cree.com/products/xlamp7090_xre.asp

The C.Crane product really isn't suited for room lighting, a fluorescent alternative, as it's use of 40 LED then require either increased focus as a spotlight or enough diffusion to significantly reduce usable output. Granted, a Cree XR-E isn't a finished product shaped like a bulb, but given different requirements than an incandescent bulb the opportunity to shun a traditional bulbed lamp fixture design, in favor of more integration, is possible.


Xmass
By SaintSinner1 on 12/16/2007 1:51:40 AM , Rating: 1
How about LEDs on xmass tree?




RE: Xmass
By SiliconAddict on 12/16/2007 2:29:33 AM , Rating: 2
been there done that.


RE: Xmass
By zsdersw on 12/16/2007 8:08:30 AM , Rating: 4
So? It's still an example of the benefits of LEDs. Holiday lighting can add a significant amount to your energy bills, so cutting that down with LEDs is definitely a smart idea.

Also.. unlike traditional Christmas lights whose color is often painted on, the color on LED lights doesn't flake off; blue stays blue, red stays red, etc.


RE: Xmass
By Spuke on 12/17/2007 1:16:07 PM , Rating: 2
Off topic a bit but you can get solar powered Christmas lights now. Fairly expensive though but definitely a consideration for me.


RE: Xmass
By TomZ on 12/17/2007 4:33:45 PM , Rating: 2
I wouldn't think these would be very good. Either they would be very dim, run for only a short time, or require huge solar panels and batteries which would drive up the cost like crazy.


RE: Xmass
By melgross on 12/16/2007 3:43:41 PM , Rating: 1
The reliability has been found to be far worse than with incandescent. They don't last more than a year, and cost more. Apparently, there is corrosion that kills the string.


RE: Xmass
By masher2 (blog) on 12/16/2007 3:52:28 PM , Rating: 2
I fail to see how a string of LEDs would suffer from more or less corrosion problems than tungsten-filament bulbs. Got some sort of reference to that?


RE: Xmass
By kring on 12/17/2007 10:33:48 AM , Rating: 2
I have them all over my house, 14 sets. it's not that they corrode faster, they corrode the same, but at a cost of $1.00 for normal vs. $7 for LED... it's 7X the cost for something that doesn't last a year. Mine from last year had lots of corrosion and I had to toss 1/3 of the sets and had to manually splice out some corroded sockets one another 1/3rd.


RE: Xmass
By BVT on 12/17/2007 1:49:23 PM , Rating: 2
Your problem is that you are buying cheap lights.

I put 3 sets in my oldest sons room in the beginning of February. They are on a timer that comes on every night for 5 hours. Not a single led has burn out or has gotten noticeably dimmer than the others. My sets cost $18 and were commercial grade.


By SiliconAddict on 12/16/2007 12:57:52 AM , Rating: 2
The room I have my home theatre in I would love to convert from traditional dimmer floods to something more efficient. However florescents are a no go due to the inability to dim, so bring on the more natural LED's.




By kmmatney on 12/16/2007 3:17:55 AM , Rating: 2
There are some compact florescents you can buy than dim now. I've been pretty happy with CFLs, I've replaced most of the lights in my house. Besides energy savings, the CFLs last a lot longer - I hardly ever have to change a light bulb now.


By Hafgrim on 12/16/2007 11:32:42 AM , Rating: 2
I really would love to finally buy some CFL's that can dim, to finish off my house with all CFL's. Also Yellow(warm) CFL's have been around a while now so thats not an excuse anymore to not buy them. I personally like the not so yellow ones myself of 4100k whiteness and higher for me. =)
p.s.
"Bright Effects" from Lowes has virtually no lag or time to full light and seem to be the best out of all the ones i have testest for no lag and warm up times. Pretty much instant.


By Spuke on 12/17/2007 1:26:38 PM , Rating: 2
I'm looking for some dimming CFL's myself for my ceiling fans.


By Hafgrim on 12/16/2007 11:34:19 AM , Rating: 2
What brand CFL did you buy that had dimming?


By BVT on 12/17/2007 1:50:40 PM , Rating: 3
www.1000bulbs.com


Consumer Replacements Available Now
By smilingbob22 on 12/16/2007 12:13:46 PM , Rating: 2
Check out http://earthled.com , looks like they have a line of direct replacement LED Light Bulbs. They also appear to be selling them through ThinkGeek.com.




RE: Consumer Replacements Available Now
By melgross on 12/16/2007 4:29:34 PM , Rating: 2
I bought two of these to experiment with. They cost $70 apiece. Pretty expensive for 380 lumens. They have more powerful models, but they cost more per lumen.

http://earthled.com/vr7.html


RE: Consumer Replacements Available Now
By GeorgeOrwell on 12/17/2007 2:30:59 AM , Rating: 1
How does the quality of the EarthLed LED light compare to ordinary tungsten incandescent lights (soft white and clear bulb) and to halogen lights?

I presume the light quality of the "EarthLed" light bulb is far better than the white LED bulbs that are found in flashlights?!?


RE: Consumer Replacements Available Now
By 91TTZ on 12/17/2007 7:14:55 AM , Rating: 2
quote:
I presume the light quality of the "EarthLed" light bulb is far better than the white LED bulbs that are found in flashlights?!?


That's doubtful, since they use the same 1 watt LEDs that many flashlights use.


RE: Consumer Replacements Available Now
By GeorgeOrwell on 12/17/07, Rating: 0
RE: Consumer Replacements Available Now
By mindless1 on 12/23/2007 10:46:26 PM , Rating: 2
I wouldn't say "scam", because buying 7 x 1W LED flashlights isn't going to be much if any cheaper than that bulb is.

It is a niche product, naturally it will cost more. However, it will be brighter than many LED flashlights for two reasons:

1) LED flashlight uses a battery which exhibits voltage drop running high current LEDs, while the supply for this wouldn't necessarily have to.

2) LED that run cooler put out more light and last longer. A flashlight is a difficult environment for an LED if meant to (designed well to) run for more than a few minutes at a time as there is limited heatsinking space available and even if it were well sunk to the exterior of a metal bodied light, it would get uncomfortably warm to hold in your hand after running for about a dozen minutes or more.

To put pricing in perspective, that bulb uses Cree 1W LED. Now 3W Cree LED that are more efficient are under $5 each in volume. Add maybe $5 for a driver circuit and $5 for a custom enclosure (bulb, heatsink, etc all integrated) so in theory today you could have a light that produces 3X that much light at a total cost of

7 x 5 + 5 + 5 = $45, BUT we have not yet built any other company overhead or profit into it yet, and it wasn't long ago the 1W LEDs cost as much as 3W cost now.

In other words, for the same money you can do better today but the price is not exceptionally high for what it is.

If this tech interests you I suggest checking out the offerings at http://www.dealextreme.com as they have the 3W Cree LEDs as well as many especially cheap driver boards, although most are set up for flashlight use but given the cost savings, some inventiveness would allow their use. For power you might pick up a small switching supply from one of the electronics surplus 'sites on the web, possibly even completely forgoing the driver boards if you have the right supply. For example a tweaked 12V switcher can be made to put out 14.8V which might do nicely to power 4 LED in series at a 3.7 forward voltage, and there are many tiny little wallwart sized 12V 1A switchers powering everything from routers to modems to scanners, etc, etc. so they're readily available.


By mindless1 on 12/23/2007 10:54:13 PM , Rating: 2
Correction - a better flashlight won't suffer so much voltage drop as it will have a better regulator design, but the heat factor is still present.

I don't agree that white LED is worse that CCFL for reading or detail work, I feel you just didn't have an LED based product that put out nearly as much light as a CCFL bulb you'd compared it to, and most flashlights try to focus for high intensity not broad beams which is harder on the eyes producing both glare and dark surrounding areas. Except casing light a long distance outside, many LED products do seem to try to focus the beam too much IMO.


one other problem
By slawless on 12/16/2007 5:30:22 PM , Rating: 3
Personally I hold great hope for LED lights. As mentioned earlier theoretically they can be 100% efficient. However even if you could make a 100% efficient LED, LEDs still work on low voltage, DC electricity. (~5v DC) Our houses have high voltage AC. (110/220v AC) the power must be transformed and rectified. both inefficient processes.




RE: one other problem
By masher2 (blog) on 12/16/2007 6:06:04 PM , Rating: 4
You're correct about the conversion losses in going from AC to DC, but its also important to remember that its not possible even in theory to make a 100% efficient source of white light. Our eyes respond best to green; colors above or below are less effective. The maximum efficiency for any white light source, led or not, is less than 40%.


RE: one other problem
By mindless1 on 12/16/2007 11:39:00 PM , Rating: 2
Relatively speaking, it is more correct to think that AC power conversion to low voltage DC is efficient, not inefficient, since it can easily be over 80% efficiency while no lights themselves achieve remotely close to this.

Similarly, if you wanted to think about power sources, fluorescents have the same inherant issue of supply efficiency.


Deep UV?
By Shining Arcanine on 12/15/2007 11:33:17 PM , Rating: 2
I thought that the light used to kill bacteria was called UVC, not Deep UV.




RE: Deep UV?
By lumbergeek on 12/16/2007 2:04:59 AM , Rating: 2
Tomeh?to, Tomahto


RE: Deep UV?
By masher2 (blog) on 12/16/2007 12:28:43 PM , Rating: 3
Two different phrases for the same concept...they both refer to any UV light shorter than around 290 nm.


They need to make better regulation circuits for them.
By 91TTZ on 12/16/2007 11:59:16 PM , Rating: 2
I cannot stand that strobing affect that I see on a lot of taillight of newer cars. When I look around the road I see those horrible red LEDS strobing.




By mindless1 on 12/17/2007 12:16:15 AM , Rating: 2
Unfortunately they seem to feel it is desirable in that given a particlar average current, achieving a higher peak momentary brightness seems more noticable to our eyes.

I agree they should think about using constant, low ripple current instead and it would be a trivial thing to do, or to modify your own car towads this end but you can't do much about someone else's car.


By TomZ on 12/17/2007 4:30:02 PM , Rating: 2
AFAIK, that's exactly what's going on. LEDs are strobed at current levels that are higher than they could be if they were turned on continuously. For example, an LED that could be run with 0.1A continuous is run at 0.5A at 20% duty cycle (20% on time, 80% off time). The average power dissipated by the LED is the same, but the perceived brightness is higher.


We're seeing our future.
By Tebor0 on 12/16/2007 12:19:01 AM , Rating: 2
I love it. There's nothing like wrapping your mind around the idea of replacing the basic light bulb. Tech trickling down at it's finest.




RE: We're seeing our future.
By Larso on 12/16/2007 7:25:39 AM , Rating: 2
I think that LED's are very nice for effect lighting and perhaps displays, but to replace basic home lighting, I just don't know. I haven't yet seen a LED light source with the same pleasent warm light as a tungsten bulb. There is just nothing like true black body radiation...


RE: We're seeing our future.
By GeorgeOrwell on 12/16/07, Rating: -1
Source Article?
By Digibit on 12/16/2007 7:16:05 AM , Rating: 2
This article seems to be very similar to a news item posted on the BBC news website a while ago (http://news.bbc.co.uk/1/hi/technology/7131358.stm)... Even the picture of the LED Christmas tree used is the same. Orignal journalism or blatent cribbing...?




Power
By Omega215D on 12/17/2007 2:23:34 AM , Rating: 2
If you want to see how bright flashlights can be check out www.inovalight.com

I have the Flood light X5 and T2 which are bright as hell and the X5 is great with battery life. LED's are great for illumination since the bulbs have a long life span.




By ThisSpaceForRent on 12/17/2007 8:33:50 AM , Rating: 2
Then if that isn't a UV filter on the DI system at work what is it? The party light for bacteria? Our filter is comparable in size to the laptop I'm writing this post on. (No the laptop is not 30 years old.)

I can see cost being an issue to developing countries, but the statement about being too bulky seems very misleading. If we're talking about applying a Western styling distribution system to a developing country then sure it may be to bulky. But how many developing countries have such an infrastructure that is comparable? If you're looking to just disinfect a source, as opposed to an entire supply, then the current technology is most certainly not too bulky.




Hrmm...
By Rhodenator on 12/17/2007 10:29:58 AM , Rating: 2
quote:
Now one place scientists are looking to plant the LED is in the home.


I spent about 30 seconds trying to find when homes were able to start using LED Lighting, but I know that I talked about putting LED lights in my home 4 - 5 years ago, because they already existed. Why are we starting to say "Now one place scientists are looking to plant the lED is in the home", if it's been over 5 years that people have been trying and discussing doing just that? Why not say something more about the line of slow adoption, I just dislike the way the article makes a reference as if it's something new and never thought of.

Sorry for being anal, it's just me =D

and yes, I look very forward to the future of LED (or better/equal replacement).




By Rovemelt on 12/17/2007 2:19:36 PM , Rating: 2
I've been looking for LED replacement bulbs and I can find 'warm' color LED's that come in around 3500K, but they seem to suffer a bit in efficiency compared to the higher color temp LED's (~6000K), which looks blueish.

With regards to the efficiency quote from Mick, this is from the wikipedia entry on CFL's;

http://en.wikipedia.org/wiki/Compact_fluorescent_l...

quote:
While CFLs are an important development in energy conservation for most lighting, LED lighting has already filled a few specialist niches such as traffic lights and may have the potential to compete with CFLs in the near future. LED lamps have current efficiencies of 30% with higher levels attainable (recently up to 85 lm/w LED`s are available) , and a lifetime of around 50,000 hours, but currently are struggling to deliver the required intensity of light output for domestic uses while maintaining a reasonable working lifespan, at a reasonable cost.


I don't know how efficiency is being calculated, but they also put CFL's at 8%. Might have to do with what Masher pointed out regarding what light we can see vs. total light output being in the calculation.

There are portable UV water purifiers for sale out there. I have no personal experience with them, so I can't comment on their quality or effectiveness or the particular one I link to below. Even some that charge by a small solar panel:

http://www.hydro-photon.com/steripen_products.html




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