The End Of The Light Bulb?

sdmonroe wrote to mention an MSNBC article discussing the likely eventual replacement of common light bulbs by LEDs. That replacement is likely to come quicker thanks to an accidental discovery announced this week. From the article: "Michael Bowers, a graduate student at Vanderbilt University, was just trying to make really small quantum dots, which are crystals generally only a few nanometers big. ... When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color. But when Bowers shined a laser on his batch of dots, something unexpected happened. 'I was surprised when a white glow covered the table,' Bowers said. 'The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.'"

Comments

Something new for moths?

[xanadu113]

Something new for moths to fly in to?

Re:Something new for moths?

[Anonymous Coward]

It would be so cool to paint your walls with quantum dots so they emit light.

Re:Something new for moths?

[Mugros]

Yes, great lamp. The insects fly to the quantum bla bla and then they are grilled by the laser.

Re:Something new for moths?

[yogkarma]

So we also change Idea Bulb Icon to Idea LED Icon?

Re:Something new for moths?

[masklinn]

Real life insect-targetted annihilators?

TA Style !

LED lights

[totallygeek]

I have been impressed with the LED lights over florescent or incandescent. The subdued lighting is fine with me and the energy consumption / bulb longevity is the best part. When my wife and I move (build a house), we will go 100% LED.

Re:LED lights

[carnivore302]

Then you (and your wife) might want to have a look at Modern Optical Engineering, or if you are into math and can also appreciate the theoretical background of LEDs, hunt for Light Emitting Diodes, by Fred Schubert, who is somewhat of the pope in this field.

Re:LED lights

[Anonymous Coward]

I have been impressed with the LED lights over florescent or incandescent.

I prefer indecent lights.

Re:LED lights

[Znork]

Unfortunately, while the subdued lighting is 'fine' there are many indications that it isn't exactly healthy. It might be ok if you're spending a lot of time outdoors, but if you're an indoors geek, you'd probably be better off with far stronger daylight equivalent lighting. And as these lights are not particularly energy efficient compared to CF, their utility might be limited.

Re:LED lights

[Anonymous Coward]

But it looks like fluorescent lightbulbs are more energy efficient.

The article states that LEDs are twice as bright as incandescent. But fluorescent lightbulbs on the market are 4-5 times brighter (ie. a 15W is equivalent to 75-100W).

So they will actually be more costly to run than fluorescent. But where a fluorescent bulb lasts up to 9 or 10 times as long as a normal lightbulb, the LEDs should last 50 times as long.

Re:LED lights

[Anonymous Coward]

What about cost to build and lifespan? Flouro bulb-replacements are pretty complex and give poor light quality. I'll keep on using halogen until a better LED or quantum solution appears - good, continuous spectrum flouros cost a bloody fortune!

Re:LED lights

[shawb]

My guess: What is more likely to happen is these microdots could just replace or augment the fluorescent material in typical flurescent bulbs, with appropriate re-engineering. Although as an LED coating this would be amenable to more portable light, such as the little LED keychain lights except with a more natural looking spectrum.

After a little research, it appears that LEDs have been designed that surpass the efficiency of compact fluoros, but these are not on the market yet. More info on on Wikipedia. However, this efficiency is for a given pure color LED, and the flourescence required to make an LED emit white light will reduce the efficiency somewhat. It would be interesting to see what the efficiency of fluorescence is with these microdots vs more traditional materials, in addition to differences in manufacturing costs and health/environmental factors.

So it will break down to we have a new tool which will be better in some circumstances. The pros and cons of will have to be weighed out in each situation. Where shock resistance and length of life is important, LEDs can have a significangt advantage over fluorescent bulbs.

Re:LED lights

[Lumpy]

and it would be a very silly thing to to.

CF lamps are at least a factor of 10 more efficient than LED's even the highest output led's you can buy. If you are looking for efficiency I strongly suggest you do what those that live ofgf grid or on DC power do.. they use Compact Flouresent or cold cathode. I can produce 100time the light with 6 watts of electricity than you can with the most advanced led lighting system available. Oh and my 6 watt CF lamp costs $9.95 while you will pay more than $100.00 for 6 watt white LED lighting source.

Please, do real research and make solid decisions on this. Dont act like a CEO and make a decision on a highly flawed article that played very loose with facts and figures.

These new "quantum dot" lights are at least 5 years off from being a real product, and certianly will not produce more light than a CF does at 6 watts for a while after that.

Re:LED lights

[OpenServe]

I have been impressed with the LED lights over florescent or incandescent. The subdued lighting is fine with me and the energy consumption / bulb longevity is the best part.
White LEDs are twice as efficient as most incandescents. However, compact fluorescents (CFLs) are twice as efficient as white LEDs. LEDs last 10x longer than CFL's, but they also cost several times what an equivalent number of CFLs would cost over the same lifetime. As a result, White LEDs are simply not economical at this time. They need to double in efficiency and quarter in price before they will compete head-on with CFLs. Right now, white LEDs are mostly useful for small tasks, such as flashlights, reading lights, nightlights, etc.

Re:LED lights

[falconwolf]

I have been impressed with the LED lights over florescent or incandescent. The subdued lighting is fine with me and the energy consumption / bulb longevity is the best part. When my wife and I move (build a house), we will go 100% LED.

Currently I use CFLs, Compact Fluorescent Lights, 12 and 15 watt bulbs that produce as much light as 60 and 75 watt incandecent or "regular" bulbs and last up to several tymes longer. But LED lights bulbs I found out about a few months back use much less energy and last a lot longer than even CFLs. I'd like to, and am working on plans to, build my own home and when I do I want to be off the grid, probably powered by solarand wind genies. Or maybe fuel cells. So I'll be using LED lights myself.

Falcon

Re:LED lights

[Anonymous Coward]

I've changed almost my entire house over to CF lights or the standard flourescent tubes. It took a few years but as I replaced older fixtures, I specifically chose ones that looked nice and would allow me to use CF lights in them and not look "ugly". The only exception is my dining room chandelier. I've actually used CF lights in my ceiling fans but they do not last too long due to the vibration I assume.

My house is 100% electric including my water supply (well pump). Here are my stats from my last electric bill for the previous 13 months:

Max kWh Usage 1926
Avg kWh Usage 1376
Min kWh Usage 939

My average bill is about $150. That max was August of this year but still only $220, July was very close to that. I blame that on both kids home on summer vacation, pool running a lot, and it was a hot month.

I use other electricity cost cutting measures besides the lights that others may not enjoy like 63-67F in the winter along with a portable keroscene heater or my fireplace (an insert) to supplement my heat pump below 25F, AC on 82F in the summer and 77F at night), running my pool filter on low speed and only when required, all outdoor lights are motion sensored, low flow shower nozzles (does not matter really because unlike city water that is higher pressue 60-80lbs?, my well pump cycles between 40-60lbs). On the down side.. I have a minimum of 4 computers running almost 24x7, my incoming water temperature is 55F so it takes a lot to heat it up and my teens take looong showers, I have a 12 year old refrigerator and another seperate freezer, my heat pump/AC unit is 22 years old and some how still running, and somewhere in the house there are at least 2 tv's running 24x7. I could cut down more and replacing my heat pump would be a good start but I am waiting until it dies.

My point? I don't know. I use CFLs and it helps.

Re:LED lights

[falconwolf]

Re:LED lights

And as these lights are not particularly energy efficient compared to CF, their utility might be limited.

By "these lights" do you mean LEDs? Because if you are then you're wrong as LEDs use something like 1/5 the power of CFL, Compact Florescent Lights. which themselves use 1/4 the power of incandescent lights:

Warning it's a pdf, Here is a lighting test, which lighting technology can produce the most light for the least power? The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Falcon

Re:LED lights

[falconwolf]

Re:LED lights

CF lamps are at least a factor of 10 more efficient than LED's even the highest output led's you can buy. If you are looking for efficiency I strongly suggest you do what those that live ofgf grid or on DC power do.. they use Compact Flouresent or cold cathode. I can produce 100time the light with 6 watts of electricity than you can with the most advanced led lighting system available..

If you thing CFLs are better than LEDs I suggest you read what "Home Power magqazine, which has some excellent articles on living off the grid, says:

Warning it's a pdf, Here is a lighting test, which lighting technology can produce the most light for the least power? The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Falcon

Re:LED lights

[falconwolf]

Re:LED lights

White LEDs are twice as efficient as most incandescents. However, compact fluorescents (CFLs) are twice as efficient as white LEDs.

Guess I have to post this again to clear up any missunderstandings about CFL and LED lights: If you thing CFLs are better than LEDs I suggest you read what "Home Power magazine, which has some excellent articles on living off the grid, says:

Warning it's a pdf, Here is a lighting test, which lighting technology can produce the most light for the least power? The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Falcon

Re:LED lights

[falconwolf]

LED lights

After a little research, it appears that LEDs have been designed that surpass the efficiency of compact fluoros, but these are not on the market yet.

LED lights are on the market now. LED: New Products. Amazon even sales some.

Falcon

Re:LED lights

[falconwolf]

Re:LED lights incandescent. But fluorescent lightbulbs on the market are 4-5 times brighter (ie. a 15W is equivalent to 75-100W).

That's wrong about LED lights If you thing CFLs are better than LEDs I suggest you read what "Home Power magazine, which has some excellent articles on living off the grid, says:

Warning it's a pdf, Here is a lighting test, which lighting technology can produce the most light for the least power? The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Falcon

Re:LED lights

[Anonymous Coward]

Thanks for the extra info - I was just going from the article :)

Looks like they could be a good move, as long as they become as easy to make as fluorescents.

I guess the environmental cost of making the lights should be taken into account as well, along with recycling possibilities. Hopefully, LEDs will stack up well there as well!

Re:LED lights

[Overzeetop]

Yikes, you must have a lot of waste in our house. My last house (one I built 5 years ago) was 4000SF with 10(+) foot ceilings and about 7kW of incandescent lighting and gobs of windows (~30,000 worth of Pella Arch Series). The walls were R-19 batt, attic was R-30-45 (varied from R-30 batt to R-45 blown, all in 24" o/c framing). I was ona well - 750' down, 2HP pump. All electric - heating, cooling, cooking, hot water. Heck, the heat pumps were a 5T 12 seer and a 3T 10 seer. My wife and I both like long, hot showers. I live in Virginia, so we've got a mixed climate. My average electric bill was $110/mo. Peak was in the winter - worst month in 4 years we blew through $200 or $220. Most summers went up to $140 max. Spring/Fall with minimal heating and cooling was about $70. We almost never opened the windows (allergies of s/o), so the AC was king in the summer. Oh, yeah - two refrigerators and a freezer, too. And we usually kept the thermostat at 68-69 in the winter and 71-72 in the summer.

Did I mention that I had 7kW of incandescent light? Yup - over 100 incandescent recessed ceiling cans. Now, I also had some fluorescent (soffits and over the kitchen island), but they were all 93+ CRI, so not terrifically efficient as fluorescent goes. Over 80% of the lighting wattage was on dimmers, however. Still, lighting is a fairly small portion of electric usage, especially when you figure that during the darkerst months, you're also typically heating, so the lights perform double duty, and in the lightest months you use less artificial light, which is good because you'd have to extract that heat through A/C.

I hate fluorescent. Flicker (even correctly working ones), poor color rendition, annoying startup/shutdown (instant vs. nearly imperceptable heat-up), poor dimming performance. It's okay for certain uses as long as the CRI is high, or you don't spend much time, but I'll likely never put CFL in my fixtures. The thought makes me shiver. I'll take a dimmed incadescent and pay a dollar or two more a month, thankyyouverymuch. (Or pay less, as it seems I've done)

Re:LED lights

[shawb]

Yes, there are LED lamps on the market, but not ones that surpass the efficiency of fluorescent bulbs.

Re:LED lights

[tehdaemon]

Sorry, the testing procedure that the article you referenced is flawed.

They take a light, shine it in a sensor at a 2.5 foot distance, and measure the light.

LED's have a built-in lens that focuses the light. so more of their light falls on the sensor. Of course this means that the LED's will test better. They get to cheat. If you redid the test with parabolic reflectors for all the lights that do not have lenses built-in, then the LED's actually measure out about the same as 100W incandesant bulbs.

OTOH, if what you want is what the article was testing (a reading lamp) LED's rock. but for general purpose lighting, LED's are not all that great. See this article for more details.

Re:LED lights

[Anonymous Coward]

Lumen per watt figures are very readily available. Footcandles per watt result from a situational test - a measure of illuminance, not total light output. A spotlight, for example, even though you can make one that ranks in the millions of footcandles(falsely claimed by manufacturers to be "millions of candlepower") with the right optics - this does not mean we've discovered a magical light energy source, this means we've figured out a way to focus the light on the light meter.

From memory:
Incandescent lighting 10-18 lumens per watt, medium wattage, cheap, moderate lifespan, light yellow color, medium wattage
Halogen (a hardened, higher temp incandescent) 15-25 lumens per watt, wide wattage range, cheap, short-lived, slight yellow color, medium to obscene wattage
White LED: 30-40 lumens per watt, extreme low wattage($$$ for lots of light), blue-white color, moderate-long life, extremely low wattage
Flourescent: 70-85 lumens per watt, blue-white to soft white color, low to medium wattage
Metal Halide:80-110 lumens per watt, moderate-long life, medium to obscene wattage
Low Pressure Sodium:120-180 lumens per watt, very narrow band red-orange color, long life, high wattage
High pressure Sodium: 100-140 lumens per watt, moderate yellow color, long life, high wattage

White LEDs are just too expensive to implement per watt - industrial longlife metal halide is my favorite lightsource, because it can be engineered to produce whatever color temperature you want, has reasonably good color rendering, and can last 20k hours. The low end is 50-75 watts, though, and that's all you'll need for a room in a house.

Re:LED lights

[Lumpy]

I have that issue and I also have the issues after it where they apologise for their errors and bad reporting and printed a revision that gave more accurate facts. LED's are better at focused point task lighting. I.E. flashlights they completely and horribly suck at area lighting the task that 90% of all lighting needs is based in. Common sense of just looking at the number of lumens per watt generated tells you that CCF is massively better.

Re:LED lights

[falconwolf]

I have that issue and I also have the issues after it where they apologise for their errors and bad reporting and printed a revision that gave more accurate facts. LED's are better at focused point task lighting.

Yea, someone else also pointed out that the test was for pointed light and not area. So I stand, er sit, corrcted. thanks.

flashlights

A few months ago I read an article on how convert a Mag-lite to use an LED and I've been thinking of doing it with mine.

Falcon

Re:LED lights

[Woody77]

There are two separate issues here:

1) Vitamin-D(or E?) generation due to sunlight exposure
2) circadian rythm timing based on sunlight exposure

For a geek, what they really need to do, if they want to actually be able to function in the rest of the world (instead of rom noon to midnight+), is to expose themselves to roughly the output of a 100W lightbulb for a period that matches up with when the sun's out. Which means that after the sun goes down, you dim the lights down. This way the body understands what time it is. If you have lights on bright late at night, you'll slowly shift your circadian rythm later and later, getting up later and later each morning...

Total darkness at work doesn't help, either. The body uses sunlight to figure out when it should be awake/asleep.

Then if you're not getting enough light exposure (real sunlight), your body won't properly produce one of the vital vitamins, and depression will start to set in (anyone can become Seasonally Affected if they don't get enough sunlight, for a long enough period of time).

Ever notice how GOOD sunlight can feel sometimes? That's the body soaking up the UV for vitamins. Always being slathered in SPF40+ will actually cause the same problem, you NEED sunlight.

Dement wrote an excellent book about this (pioneer of sleep studies at Stanford).

Re:LED lights

[Grishnakh]

Your electric bill sounds pretty ridiculous. I think your main problems are your heat pump and refrigerator. These probably use a lot more power than your lighting does. Replace the heat pump with a new high-efficiency one and that should cut your heating/cooling costs in half. 22-year-old heat pumps have lousy efficiency, and since it's probably on its last leg anyway, you're probably spending more money in the long run by keeping it around than you would be replacing it now.

Newer refrigerators are likewise more efficient than older ones, and more convenient to boot.

You're not using Intel chips in your computers, are you? (Unless they're Pentium Ms, which are very efficient.) If you're running them 24/7, you'll save a lot of power using the newest Athlon64s with Cool n' Quiet.

Why would you run TVs 24/7? If this is really true, you might want to think about replacing them with LCD models.

Re:LED lights

[Anonymous Coward]

And say bye-bye to your cash when you pay your next electricity bill?
I work in the aircraft industry, where marketing is dictating that LED lighting be used a s a standard. The troubles we are having due to increased weight, increased power consumption and lower reliability are just not worth it.
Basically, to make LED's bright enough you need to give them more power than fluo tubes, and they will burn out more often due to this.

Re:LED lights

[Znork]

Ah, very interesting, and I was quite surprised. I did take a serious look at it tho, and did the calculations, as I've been reading quite a lot about horticultural lighting for my orchids as a side-geek-hobby :).

Unfortunately it seems the high efficiency of the LED's in the study is due to the directionality of the light, not as a direct result of light output. The highest efficiency LEDs I've seen are around 55 Lumens per watt, and they're orange or green. The highest efficiency white ones appear to be around 35lm/W. As a comparison, the highest CF bulb I actually have is around 66lm/w, and HID lighting goes up to almost twice that per watt.

So, for specific purposes (especially replacing halogen reflector spotlights) the LED's may be useful, but for general purpose light-level increase they're not quite as efficient as CF's yet.

They definitely show promise tho, so I'll be following developments, especially from the geeky compose-your-own-spectrum point of view :).

Re:LED lights

[falconwolf]

Unfortunately it seems the high efficiency of the LED's in the study is due to the directionality of the light,

Yea, others had pointed out the study cited that I posted was flawed as it only tested light at a point and not over an area. Someone else who has the printed edition said the magazine published a correction in the next issue explaining this messup.

Falcon

This brings up an important question

[Anonymous Coward]

How many cats does it take to change a quantum dot?

Re:This brings up an important question

[Geoffreyerffoeg]

Two, and you don't know which one will actually change the dot until the light turns back on.

Re:This brings up an important question

[Pfhorrest]

Depends, are they alive or dead? Or haven't you observed them yet?

Re:This brings up an important question

[IcedZ]

It depends... are we talking about Schrodinger cats???

Re:This brings up an important question

[vertinox]

The other problem is that if you can tell wether the light bulb is on or off, you can't find out where it is.

Also, if you can locate where the light bulb is in your house, you won't be able to tell if it is on or off.

Re:This brings up an important question

[RazorRaiser]

don't you mean "How many dead cats would it take to make one?"

Re:This brings up an important question

[ThreeE]

Meow.

Re:This brings up an important question

[LiquidCoooled]

But if you turn the light back on and discover you have chosen the wrong cat, does the light come on at all?

Re:This brings up an important question

[Anonymous Coward]

How many cats does it take to change a quantum dot?

Both.

Re:This brings up an important question

[fbjon]

These shall henceforth be referred to as Heisenbulbs.

Re:This brings up an important question

[Anarke_Incarnate]

And is the cat dead until you open the box to look at it?

Re:This brings up an important question

[Ignominious Cow Herd]

"Can you see me now?"

"Good."

Re:This brings up an important question

[shawb]

And if you don't check the cats, does that mean that the light is in a probabilistic state between being on and off? I wonder what would that do to the efficiency rating of items incorporating this material.

And I'd be willing to bet that the SPCA would have a vocal objection to the use of the possibly endangered Felis cattus schroedingerae .

Re:This brings up an important question

[debiansid]

actually, according to heisenberg's principle you'll never be certain who did it... there's equal probability of both cats doing it...

leds

[jsmucker]

I will go to leds when they meet my budget....just a matter of time.

Re:leds

[RedLaggedTeut]

I will go to leds when they meet my budget....just a matter of time.

Or the time of matter, since you can't measure both due to Heisenberg.

Re:leds

[Anonymous Coward]

Let's see... I have 1 iBook, 3 PowerBooks, 1 17" iMac, 2 iPods, and soon an iPod nano. Since I'm a filthy rich Apple user, when is Jobs going to come out with the iLED?

Re:leds

[yabos]

Duh, just use the Heisenberg compensator!

what the

[Anonymous Coward]

so..umm... to get light from this , I shine it with laser ?

...yea..i can always run off another line from my 220 /110 v to a laser source and direct that at this....

yup, goodby common light bulb.

Re:what the

[chris234]

so..umm... read the article? The coated a blue LED with the dots in a substrate and it gave off the white glow again.

It's about damn time!

[Mysticalfruit]

Considering that the average lightbulb creates more heat than light, this is great!

Re:It's about damn time!

[winkydink]

Considering that the average lightbulb creates more heat than light...

Kind of like most slashdotters!

Re:It's about damn time!

[joostje]

Considering that the average lightbulb creates more heat than light, this is great!
As lightbulbs create about 95% to 98% heat (the rest is light), and modern LEDs about 85% to 96% heat, the LEDs still create more heat than light.

reference

Re:It's about damn time!

[Jedi Holocron]

Yeah, technically the LED itself doesn't throw out heat with the light it produces...however the "driver" (similar to a ballast on a flourescent fixture) or the electronics behind running/controlling the LED does produce a lot of heat. Reducing this ancillary heat production is another limiting factor to the adaptation of A Lamp replacement LED "bulbs".

Re:It's about damn time!

[DrLex]

Actually LEDs do produce heat, albeit the ratio of heat/light is much lower than with incandescent bulbs. The common LED is designed for a maximum current of 20 ~ 30mA, and at these currents the heat production is negligible. You can drive them at a higher current, but then the heat production becomes significant and can cause the LED to burn out (and at real high currents, the junction simply breaks down immediately). The more performant Luxeon LEDs are attached to a tiny heatsink and the high power ones (3W and 5W) require an additional heatsink to use them beyond 1W.

Re:It's about damn time!

[Hedon]

When I was finishing up my PhD (on InfraRed LED's) about 5 years ago, HP was making high-efficiency Red LED's with 50% light output efficiency. At the same time commercially available blue (GaN) LED's were only 10% efficient. Green LED's were somewhere inbetween.

I should really google for the state-of-the art visible LED efficiency, but am hoping for someone to post a more informative post following this one.

Re:It's about damn time!

[hey]

Unless you give in a cold place -- where its nice of have as many sources of heat as you can get. Also, what about the fate of Easy Bake Ovens?!

Re:It's about damn time!

[Midnight Thunder]

One thing to note is that the lights that produce heat are actually not so bad in cold climates, since they help heat the room. It is only in hotter climates where this becomes an issue.

Re:It's about damn time!

[MobyDisk]

This is where the wikipedia is great but it also shows weakness. The table shows fluorescent bulbs as 6.6% - 8.8% efficient. The following paragraph says fluorescent bulbs are 40% efficient. The table lists references, but the references are either bad links or corporate marketing info.

Does anybody have any real authoritative information on this?

Re:It's about damn time!

[cnettel]

Not too true. Even in a cold climate, EVEN when you use electric heating, you can get higher efficiency by a phase-change compression system for heat exchange, "pumping out heat" from the air leaving the building.

Re:It's about damn time!

[rco3]

Cree are claiming a white (phosphor-based) LED with 50% wallplug efficiency, according to Don Klipstein's Lighting Site. The link from his site is dead, though. Cree are also claiming that lab versions of a current LED achieve 70 lumens/watt, and a total of 85 lumens at 350 mA. You'd still need about 25 of these to get the light output of a 100W incandescent, though. Probably cheaper to drop 300 5mm LEDs into a dedicated fixture - Chi Wing's eBay store will sell you 300 16,000 mcd (maybe...) white LEDs for a little over $100, shipped. However, I can't really see spending $100 for a 100W bulb, ya know?

OTGH, though, I can see a distinctly untapped market for specialty, artistic LED fixtures that simply can't be realized with incandescents or fluorescents.

Re:It's about damn time!

[schoaff]

I know the companies that sell LED runway lights have to offer heating kits since they don't melt the slow that hits them as well as the lights they are replacing.

Re:It's about damn time!

[pintomp3]

not surprising since the way they produce light is through heat.

Re:It's about damn time!

[John Harrison]

What does that have to do with lightbulbs? Your statement deals with heating in general.

Re:It's about damn time!

[minus23]

I want to learn how to solder up a bunch of leds and make some interesting lights. I can't find a good book or info through google on how to wire them up. (like is it series or parallel, both.. is there such a thing as ohms for powersupplies?)... I've found some powersuplies for the job though. Apparently 12 volt is all the rage and the models vary from 25 led powerability to 350 LED powerability. I'm just missing the key info on if you wire LED's all up in Parallel or not really. (My brain is currently wired for speaker hook-ups... not voltage). Sorry for the sentence structure... I blame this cramped laptop keyboard.

Re:It's about damn time!

[Elrac]

Something interesting and useful to know is that one LED takes about 1.5 volts to operate. Red ones take a little less, blue ones a bit more. If you want to hook LED's to a 12V source, you need to hook about 8 of them in series, that is, end-to-end in a daisy chain. Note that LEDs have polarity, i.e. they will only light up if the correct end of the LED is hooked up to plus. So you need to hook the short lead on one LED to the long one on the next, consistently. If your power supply is AC, this still needs to be observed, but then it doesn't matter which end of the chain goes to which pin of the power supply.

If you want to hook up even more LEDs, then you should hook up several such 8-LED chains in parallel to your power supply.

Re:It's about damn time!

[syukton]

Something interesting and useful to know is that the other reply you received to your post is totally incorrect.

First, LEDs are current driven, not voltage driven. The voltage difference between + and - determines the amount of current the device will consume, but if you can regulate the current you can run the device at 100V no sweat. You will of course need to dissipate any additional heat (usually in the device you're using to do the current limiting, sometimes a resistor, sometimes a more exotic circuit) created, but the very important thing to understand about LEDs is that their current absolutely determines their light output after you surpass a certain threshold voltage.

The relationship between the +/- voltage difference and the amount of current consumed is not the same for every kind of LED. LEDs require different chemistry in order to produce different colors, and this makes them have differing performance characteristics.

And another thing to consider is how the LEDs are packaged. Some 8mm packages have 4 chips inside and their rated light output is measured at a regulated input current of 80mA and not 20mA as for most single-chip devices. Also, some blue devices consume 30mA while reds only consume 20mA. Again, this depends on the chemistry. Now, also, taking packaging into consideration, a Luxeon device from Lumileds and a BL-3000 from Lamina Ceramics have totally different performance characteristics because of their chemistry, construction, packaging, and so forth.

You have two choices: Limit the voltage so that the device does not consume as much current, or limit your current and ensure that the voltage simply exceeds the maximum. Ultimately you need to regulate the current because the amount of current consumed (taking into consideration the device's ultimate efficiency) is directly proportional to the amount of heat generated in the chip itself.

You see, LEDs don't generate heat in their light path (radiant infrared travelling in parallel with the visible light, like the "heat" of the sun or a candle), but the chip itself does get rather hot, and if that heat isn't dissipated the LED chip will become physically damaged. Some of the materials used have melting points below 120 degrees, a temperature easily achieved by an LED not properly heatsinked.

So here's some tips: When you make LED boards (whether addressable matrices or simple blinky lights) you want to use a metal-core PCB or leave a portion of the LED's leads exposed in order to help dissipate the heat generated at the chip core and ensure longer chip life. LEDs don't just "burn out" one day, they will get dimmer slowly over time, and you can maximize that length of time by running them at less than their rated current, by cooling them actively or passively, and by using PWM to modulate their output.

Don Klipstein maintains a good set of information about LEDs: http://members.misty.com/don/ledx.html

Re:It's about damn time!

[minus23]

Ahh... thank you! I was just reading about the volt drops on another page... the methods for wiring wasn't talked about. Your post makes it all click in my brain now. Thanks again. =) I think I better pick up a guide to basic electrical engineering. I can really see the idea of LED light design being a hobby for a lot of people.

Re:It's about damn time!

[Elrac]

syukton, you absolutely deserve the "+5 Informative" you got on your post. Most of what you said is correct, and you provide an abundance of information. However, I believe I served my parent poster better than you did, by not swamping him with information he may not know what to do with. I based the level of my response on his claim of not even knowing whether to wire in series or parallel. I'm happy to see he plans to go off and learn some EE basics now; that should help him put both my information and yours in perspective.

I know my Ohm's Law at least as well as the next guy, and it so happens that just a couple of weeks ago I helped someone calculate/select the appropriate voltage drop resistor he needed to run a single LED off a 24V supply. Knowing the current rating of the LED(s) involved makes such a question amenable to being treated as an exact science.

However, knowing nothing about the parent poster's LEDs, not knowing what he knows and not wanting to confuse him too much, I chose the pragmatic approach and suggested a setup that will let him experiment in a way that will at least light up his LEDs and give them a fighting chance to survive for a few minutes. If his LEDs become amazingly bright but expire after a short time, I trust he'll consider fine-tuning the circuit.

My principle was that, once you get past the diode's cutoff voltage, the internal resistance of a LED is at least vaguely linear. So the voltage drop across LEDs will go up as the current goes up, eventually limiting current just as surely as if you were to control the current instead of the voltage. You'll notice that, while not resorting to chemistry (or mention of the fact that blue light photons carry more energy than red), I mentioned that red LEDs usually take a little less voltage than blue.

So: I take exception to your contemptuous and thoughtless labelling of my entire post as incorrect. It was simplistic, to be sure, but based on excellent knowledge of the subject matter and solid pragmatic reasoning.

Re:It's about damn time!

[syukton]

Plenty of electronics tutorials are available here:
http://www.iguanalabs.com/maintut.htm

I ordered my first electronics kit from Iguana Labs after reading their tutorials four or five years ago.

Re:It's about damn time!

[syukton]

The inaccuracy of your post was more what you stated about voltage drops, something I didn't directly address. Most individual-chip 5mm red LEDs drop 1.8 to 1.9 volts, not 1.5. The old, not-very-bright red LEDs which are difficult to find these days were of the 1.5 volt variety, but good luck finding those now. (Who would want to anyhow, with the ultrabrights available?) And today's blue LEDs require 3.4 to 3.6 volts to operate.

But you're right, your post was simpler and more helpful and that's why you got a thankyou and I didn't. Point taken. :)

Not sure this discovery is necessary

[gvc]

White LEDs are already 3 times as efficient as mercury fluorescent, and fluorescent tubes are 3 times as efficient as incandescent. They (fluorscent and LEDs) can get pretty good colour accuracy, too, if they want to. The only thing holding them back is price. I'm not sure what this new invention might bring to the table in that regard.

Re:Not sure this discovery is necessary

[jumpingfred]

Can you point me to documentation of LEDs being 3 times as efficient as fluorescent? What I have mostly seen is that they are about the same efficiency. With the LEDs being about 3 to 4 times the cost.

Re:Not sure this discovery is necessary

[Jedi Holocron]

No, actaully, the thing holding back LEDs from practical home applications is the color of the light they produce. More specifically the color temperature.

Typical incandescent lighting comes in somewhere around 2800-3200K. White LEDs live somewhere around the 5000-7000K range. When an efficent LED source can be made at a color temperature similar to that of incandescent lighting...then you'll see it take off in as a replacement for a standard A Lamp.

This same color issue relates to the slow adaptation of Compact Flourescent lamps in homes. Only recently have they produced flourscent fixtures that have a similar color temperature to incandescent lighting.

Cost is certainly a factor...however if it LOOKS bad--meaning if it makes stuff look like crap to the average eye because it is the wrong or unexpected color temp--then people aren't going to use it no matter how cheap it is.

Re:Not sure this discovery is necessary

[gvc]

It is the incandescent colour that is the wrong temperature, not the LEDs. Mid-day sun is nominally 5600K, and morning/evening higher. So why do you want to emulate candle-light?

Completeness of spectrum is another issue. Cheap fluorescent tubes have huge mercury spikes and little red - maybe 55% on the accuracy scale. Good tubes achieve 95% - a marked difference. This is independent of the colour temperature.

White LEDs (at leat the ones you commonly buy today) are also fluorescent, but with pretty decent spectral accuracy. It would at least in theory be possible to build an RGB array of monochrome LEDS that would produce apparent white light.

Re:Not sure this discovery is necessary

[pintpusher]

Current white LED fixtures put out color tempuratures around 5000K or more, which while close to "daylight" can be a fairly harsh blue-white light especially when compared to the common incandescent bulb putting out more like 3000K give or take. In the house, this can be pretty harsh light (think of that flourescent tube in the kitchen at 2:00 AM). Some fixtures attempt to make a warm glow by mixing in some red and yellow LED's in the matrix but frankly I think this looks stupid and doesn't really work. Also, white LED's are relatively expensive compared to colored LED's. I think the point here is that this quantum dot mixture could be used to generate a soft-white color, using current colored LED technology, less expensively than white LED's.

Re:Not sure this discovery is necessary

[John Hasler]

> Only recently have they produced flourscent fixtures that have a
> similar color temperature to incandescent lighting.

I specified flourscent fixtures that have a similar color temperature to incandescent lighting more than thirty years ago.

Re:Not sure this discovery is necessary

[zippthorne]

Not to mention that laser is just about the least efficient source of light.

Re:Not sure this discovery is necessary

[Jedi Holocron]

So why do you want to emulate candle-light?
I never said it was a good idea, just that IMO this is what is holding up the adoption of white LEDs. This is what people expect.

Completeness of spectrum is another issue.
Yes, Color Rendering Index rating is also an important factor that I did not mention. However, isn't the CRI index also tuned to incandescent lighting, because this is what the eye expects?

Re:Not sure this discovery is necessary

[QuietLagoon]

White LEDs are already 3 times as efficient as mercury fluorescent, and fluorescent tubes are 3 times as efficient as incandescent.

From the article, LEDs produce twice as much light as a regular 60 watt bulb. I'm really not sure how to think about all of this. If LEDs produce twice as much light as a regular 60 watt bulb, how does that make LED lights better than compact fluorescent bulbs, which can produce four to five times as much light as an incandescent bulb of the same wattage?

What is missing in this discussion is the actual power used by all these devices.

Re:Not sure this discovery is necessary

[ottffssent]

Ultimately it's not pure price (initial cost) that will determine the success or failure of alternative lighting. Cost is obviously a factor, but there are enough situations where the up-front costs are secondary to the lifetime costs in determining whether a purchase will be made. And in many situations the replacement cost includes substantial extra costs (manpower, equipment, etc) over and above the light's purchase price, which make fluorescents and LED lighting relatively attractive.

As yet, LED lighting has certain problems other than its stupendous cost. In high-power situations, such as is required for room lighting, LEDs actually aren't more efficient than long-bulb fluorescents. They still last quite a bit longer and produce nicer light, but not enough to justify the cost. Assuming the latest Nichia and Luxeon LEDs represent an improvement on past technology that can be sustained, the future for LED lighting looks good. Other than price, the lights have little to hold them back. They're as good as or better than existing technology in nearly every respect, but the technology is still young, whereas incandescent and fluorescent lighting are both mature technologies with relatively less room for future improvement.

Unless this new technology exhibits a greater efficiency, has greater longevity, is substantially cheaper to produce, or exhibits some other dramatic improvement over current LED lighting, I don't see how it's really relevant. It may become so in the future but so far it looks like an interesting laboratory result, not an interesting lighting development.

Re:Not sure this discovery is necessary

[DrLex]

It is the incandescent colour that is the wrong temperature, not the LEDs. Mid-day sun is nominally 5600K, and morning/evening higher. So why do you want to emulate candle-light?

Maybe because it looks cozy? I know many people who hate the typical fluorescent tube light because it's too harsh. When watching TV (or doing whatever) late at night, people don't want to have some bluish light shining in the background. It's as if you forgot to sleep and the first daylight is already shining through the curtains ;)

Re:Not sure this discovery is necessary

[Trillan]

There's no wattage listed for the LED bulbs. However, they do specify the light source was a bright blue LED. If we assume it is the most power hungry LED currently available, it's about 5 watts. That means this bulb is producing light equivalent to a 120 watt incandescent bulb at 5 watts, or roughly 24 times as much light per watt as incandescent.

Re:Not sure this discovery is necessary

[QuietLagoon]

If we assume

That's the part that bothers me. :-)

I'd rather the wattages be stated explicitly.

Re:Not sure this discovery is necessary

[QuietLagoon]

Looks like my skepticism was correct. A quick run through google found this

Although they are considerably more expensive than ordinary lights, they are capable of producing about twice as much light per watt as incandescent bulbs

Re:Not sure this discovery is necessary

[farquharsoncraig]

A second significant difference, according to Rosenthal, is that it should be considerably easier to use the magic-sized quantum dots to make an "electroluminescent device" - a light source powered directly by electricity - because they can be used with a wider selection of binding compounds without affecting their emissions characteristics. Other research groups have reported stimulating quantum dots to produce light by applying an electrical current. Of course, those produced colored light. So, one of the projects at the top of Rosenthal's list is to duplicate that feat with magic-sized nanocrystals to see if they will produce white light when electrically stimulated.

http://exploration.vanderbilt.edu/news/news_quantu mdot_led.htm

So, if applying current to the quantum crystals works in the case of these "magic" sized crystals (electroluminescence) to produce the same kind of white light, then the LED source can be eliminated, rather than having the crystals as a sympathetic phosphorescing medium.

Re:Not sure this discovery is necessary

[Slashdiddly]

Sure, I imagine a hundred years ago the fact that incandescent bulb gave 2800K to candle's 1200K really hindered its adoption. Because candles were what people came to expect.

No, the sibling poster is right - daylight is the real measuring stick here, not 100-year old human technology.

Re:Not sure this discovery is necessary

[Anonymous Coward]

Colour temp is only art of the story. Colour rendering index is the other. Three lasers (very narrow bandwidth) could give you the desired colour temperature, but they're CRI would be stuffed due to the light consisting of three narrow peaks rather than a continous spectrum. LEDs and most fluorescent lights also don't have nice spectrums, instead they have multiple peaks.
I think another reason I have trouble liking fluorescent lights is because incandescents are smaller sources of light which provides nice shadows, whereas fluorescent tubes are more like an overcast day. But LEDs could help there.

Re:Not sure this discovery is necessary

[Anonymous Coward]

The article is a load of marketing bullshit. Any lightsource in sufficient quantities produces more than twice as much light as a regular 60 watt bulb. There's certainly no single LED which does this. The best in consumer range so far are 5 watt LEDs which, despite their higher efficiency, don't put out that much light.

LEDs also produce heat, and not just "it's there but it's so little you can't feel it" heat. The high power LEDs on the market need proper cooling or they don't survive the first couple of seconds.

The efficiency of LEDs is somewhere between incandescent lighting and fluorescent lighting if you want reasonably bright lights sufficient for lighting a home. Even fluorescent lights produce heat. Touch a compact fluorescent sometime.

Re:Not sure this discovery is necessary

[SuperBanana]

The only thing holding them back is price.

No- many things are holding back LEDs.

• They produce light efficiently (not THAT efficiently) but don't produce that much light compared to a very simple single-bulb HID or fluorescent tube (by the way, which tube are you basing that "3x" on? T12, T10, or T8? Because T8's are MUCH more efficient that T12's). It takes a HUGE number of LEDs to replace ONE T8 fluorescent tube- and that tube costs a few dollars tops, because it is very easy to make. Right now, a single Luxeon white LED sells in 100-1000 unit quantities for well over $10-20, and produces 1-5W. A T8 bulb will produce 30-40W, and costs RETAIL about $5.
• They require new reflector designs and light spreaders, since they are a VERY small point source. A lot of work goes into making light sources produce even, smooth lighting that won't generate harsh shadows- point sources make this job a real bitch. Point source also means that despite relatively low heat output the heat is very localized, and that means PCBs must also be heat spreaders, complicating assembly/design/manufacture further. You can't just toss them on a PCB. Companies like Luxeon now sell them on little PCBs with the necessary spreader etc, but now you're not just talking about buying an LED, you're buying a whole assembly for your product...$$$.
• Related- while they have a long life before failure, most of the high-output LEDs drop in light output very significantly, within a year or two of continuous operation 10-20 degrees above room temperature. VERY few LED manufacturers disclose this upfront- and virtually ALL the companies hawking LED products fail to mention this nice little caveat. Furthermore, just because the LED is rated to, say, 100,000 hours- doesn't mean it won't burn out because the company that made the device it is part of didn't botch the job on current+voltage regulation, heat dissipation, etc.

I know everyone thinks they are the second coming of Christ, and they do have some wonderful applications (like traffic signals and car brake lights)...but they're not the end-all be-all.

Re:Not sure this discovery is necessary

[Anonymous Coward]

I have worked as an lighting engineer, and your statement about fluorescent lamps is not true. They are about 30% efficient, yielding up to 100 lumens per watt.

Re:Not sure this discovery is necessary

[gvc]

There are several reasons why they might hate fluorescent: flicker, noise, poor color spectrum, prejudice. Not necessarily color temperature. The first three are overcome by electronic ballast, high accuracy fluorescence, and the choice of whatever temperature you like.

Re:Not sure this discovery is necessary

[fossa]

Bulb Efficiency (lumens per watt)

• Incandescent: 14-17.5 [1]
• White LED: 29-37.5 [1]
• Fluorescent: 50-100 [2]

[1] Why LEDs can be 10 times as efficient as incandescents in some applications but not in general home lighting!
[2] Are fluorescent bulbs really more efficient than normal light bulbs?

I'm a bit surprised at those fluorescent numbers... I don't have the box to one of my fluorescent bulbs handy to double check that, but I do know that while not as hot as incandescents, they become very hot to the touch when in use. I've never touched a lamp sized LED bulb however.

One disadvantage of fluorescents is that they contain mercury. Newer fluorescents may have found a way around this however; I'm not sure.

Not surprisingly, many of the websites I saw talked about future improvements in LED tech with goals around 100 lumens per watt.

Re:Not sure this discovery is necessary

[K-Man]

A GE Starcoat F32T8, available in most hardware stores, gets 2650 lumens, or 82.8 lumens/watt.

Re:Not sure this discovery is necessary

[Anonymous Coward]

The color of "daylight" changes throughout the day and depends on factors like cloud cover too. In the evening, when people use artificial light at home, there is no natural daylight (some reddish light around sunset). Light which is too blue for the time of day gives the wrong signals to your body and messes up your hormone cycles, especially because it is orders of magnitude darker than the "real" 6500K light. Incandescent lights produce a full spectrum of light, whereas fluorescents and LEDs mostly produce a few peaks in an otherwise dimly lit spectrum (resulting in poor color reproduction and some unwanted, albeit rare, biological effects).

If nature's your measuring stick, then it should be dark after sunset.

Re:Not sure this discovery is necessary

[tricorn]

The eye can adjust to color temperatures quite well. What the CRI measures is the completeness of the spectrum, not the temperature. The color temperature is based on only the summed effect of the different frequencies. You can have vastly different spectrums that result in the same color temperature, for example in a television where only three different fairly narrow bands are used to produce a wide range of colors.

Two problems with using such narrow bands is that different people have different frequency sensitivities, so an image that looks correct for one person won't look "natural" for another (I've often wondered how effective going to a 5 or more band system would be for television); and that something that has its own narrow bands of reflected color that don't match the bands of incident light will look different than it would in "true" white light (of whatever color temperature).

With quantum dots effectively spreading the bandwidth of the light source into a wide spectrum light (which is not a new idea; I'm not sure why this is being considered a revolutionary new discovery, unless they were using novel techniques to produce the right mix of the right sizes), you could use any other low-power light source, not just LEDs. LEDs are convenient for some things because they can be used at very low power and last a long time. Where you need more light, you could use quantum dots with low-pressure sodium, for example, or conventional fluorescent bulbs except using quantum dots with a wide spectrum to do the fluorescing. The article also mentioned but didn't expand on using direct excitation with electricity to get quantum dots to give off light, which could be even more efficient.

Re:Not sure this discovery is necessary

[Trillan]

I suspect that "half" figure is very conservative. The first paragraph of that article is:

"Take an LED that produces intense, blue light. Coat it with a thin layer of special microscopic beads called quantum dots. And you have what could become the successor to the venerable light bulb."

I don't even think we have 15 watt LEDs, let alone 30...

I agree it would be good to half good numbers, though.

Re:Not sure this discovery is necessary

[westlake]

I imagine a hundred years ago the fact that incandescent bulb gave 2800K to candle's 1200K really hindered its adoption. Because candles were what people came to expect.

The mid 19th Century was home was lit by natural gas (if you could afford it) or by kerosene and other petroleum based lamp oils (dangerous).

Think for a moment how fifty to seventy-five years of experience with gas illumination affects interior design, men and women's fashions, cosmetics, etc.

There were real barriers to change, Competition to Edison's Lamp

Re:Not sure this discovery is necessary

[CaseyB]

A lot of work goes into making light sources produce even, smooth lighting that won't generate harsh shadows- point sources make this job a real bitch.

Wrapping the point source in a simple translucent bulb qualifies as a "real bitch"? The engineering field isn't as far along as I thought it was.

Re:Not sure this discovery is necessary

[tricorn]

There's nothing magic about using LEDs as the light source to excite the quantum dots. Use a standard fluorescent bulb, except use quantum dots instead of whatever phosphor is normally used (different ones produce different spectrums, which is how you get "warm white" vs "cool white" vs "natural" vs "grow lights", etc). These would just be a wider-band spectrum "natural" than current phosphors can do.

Re:Not sure this discovery is necessary

[raygundan]

LEDs get pretty hot. I built an LED headlamp for mountain biking at night with a 3W Luxeon Star LED, and it gets hot enough to need a heatsink backing to keep from frying itself. And that's only a 3W bulb. The heat is concentrated in a smaller area, and I'm sure there's less of it than with incandescents, but it's still fairly warm. It would be quite hot at a bulb-equivalent wattage, I imagine.

Re:Not sure this discovery is necessary

[QuietLagoon]

I suspect that "half" figure is very conservative.

It's the only number they give. I've no reason to doubt it, other than it is lower than I would like to see.

They also say "could become", not "is", the successor to the venerable light bulb. To me that means that much work needs to be done.

One benefit of this technology over compact fluorescent bulbs is a better emission spectrum.

Re:Not sure this discovery is necessary

[Jasin Natael]

I can relate to this. My wife made me replace an excellent digital camera (which I really liked) because the color temperature of the flash was too high (blue) for her complexion. Outdoor pics were fine, but when the flash was used, she always hated how she looked in the resulting pictures. People are very picky about color temperatures, often without realizing it.

--Jasin Natael

Re:Not sure this discovery is necessary

[ballpoint]

No, actually it's not the color temperature (your eyes/brain adapt) but the discrete spectrum that is the problem. Incandescents, being close to a black body emitter, have a continuous spectrum. Most LEDs however are monochromatic; white LEDs are made either by combining three monochromatic LEDs (RGB) or by exciting a yellow fluorescent with a blue LED. Neither method yields a continuous spectrum. CFs are slightly better, but not much.

If a pigment has a high-Q reflection peak at a certain frequency, and absorbs all the rest, but the LED doesn't emit light at that frequency, the pigment will remain dark.

In reality you won't encounter pure pigments too much, but many colors seem dull and lifeless under non-continuous spectrum lighting. Some people don't notice, but then some people don't seem to notice anything at all.

So unless that problem is solved, I won't install LEDs or CFs in my house except in places where it doesn't matter. I prefer 12V halogens powered by a stabilized 11.5V power supply. They seem to last forever (around four years, I've got some in my living room that are 8 years old) and produce a non-flickering, lively and lovely light. As to the power consumption: lights are on much longer during the long dark winter evenings where the generated heat isn't a total loss. Rising fossil energy prices are making heating by electricity less of an economic disaster anyway.

Still, it would be cool (or warm :-) to be able tune the color of the light.

Re:Not sure this discovery is necessary

[Omestes]

Actually most galleries use around 3000k for lighting, even if it not accurate, people prefer it more than natural 5000k light.

Re:Not sure this discovery is necessary

[MichaelSmith]

...light spreaders, since they are a VERY small point source...

Of course you have to use so many LED's that you wind up with a large surface area anyway.

I know everyone thinks they are the second coming of Christ, and they do have some wonderful applications (like traffic signals and car brake lights)...but they're not the end-all be-all.

They have been heavily used in cheap bicycle tail lights for about 15 years, with no analysis at all of the safety issues. These devices pulse at 9-12 Hz, close to several of the natural frequencies which exist inside the brain. Proponents claim that pulses at this frequency are naturally more visible than steady sources, but they don't go so far as to explain why.

For me, these weak LED lights are no alternative to a tail light which puts out a lot of light. But it is difficult to convince an observer that this pulsing light source is not much brighter than a comparable steady source.

My conclusion: we need to resist the tempation to pulse these devices at any frequency between 2 and 200 Hz. Of course they are going to be pulsed at > 1kHz for efficency reasons.

Re:Not sure this discovery is necessary

[Anonymous Coward]

It probably wasn't the flash, but inadequate UV filtering on the optical path. The sensors (CCD, etc) in digital cameras tend to pick up UV a little too well, and it gets stored in the image as light intensity.

For women, this becomes a problem, because almost all cosmetics sold reflect UV pretty well, especially foundation. The end result is, that a digital camera with poor UV filtering, taking a photograph of a woman wearing foundation, more often than not results in the woman's face and upper neck looking brighter than the rest of her skin.

Re:Not sure this discovery is necessary

[njh]

I bought some warm white leds for replacing grain-of-wheats in a vintage radio indicator. A white led is usually just a blue led with a yellow fluorescent coat. By using more or less yellow you can get any temp from about 2000K up to 10000k. The problem with LEDs as lights is their high cost per watt, nothing else. I can pick up a compact fluoro for a few dollars and get 150W incandescent equivalent. No LED comes close to that.

Most people prefer high temperatures for internal lighting - look at the use of halogen downlights and more recently, HID spots in shops. Low temps are used mainly for mood or cultural reference (ye olde).

Re:Not sure this discovery is necessary

[dangitman]

Of course you have to use so many LED's that you wind up with a large surface area anyway.

This doesn't have much effect on "spreading" the light anyway - as each LED puts out a very small circle of light that is very directional. So, you really need to bounce the light off a reflector, or use a diffusing lens - to get anything approaching the "soft" light we expect from flouros and diffused incandescent.

Re:Not sure this discovery is necessary

[CharlieG]

Also, a lot of folks don't think about Mantiles - they really change the color temperture of light, and even kerosene lamps can have mantiles - which REALLY raise the color of the light

Re:Not sure this discovery is necessary

[WuphonsReach]

Since I was just at the store this week, a selection of compact fluorescents:

Panasonic GenIV, 14W 800 lumens (57.1)
- Very small bulb that can fit into any place that a regular bulb would fit (although it's not round)

Generic 26W, 1600 lumens, 10k hours (61.5 lumens/watt)

Generic 9W, 540 lumens, 10k hours (60 lumens/watt)

Prices on the CF bulbs have gotten a lot better over the years, most of them are down around $6-$7 for a single bulb compared to $10-$20 a few years back. The fact that you don't have to replace them as often is a big bonus.

Re:Not sure this discovery is necessary

[Overzeetop]

Based on personal experience, it's not necessarily the color temperature but the "completeness" of the spectrum. That said, it is also a bit unnerving to have a color temperature inconsistant with light output. A 3000K, 15W CFL lamp looks creepy (don't believe me? put one in a big globe fixture in an old building and turn just that light on at night. Creepy, I guarantee). In the incandescent world, brighter corresponds to higher color temperature, and we're "used to it". Once you get to a certain brightness, color temperature is just a matter of matching the scene.

Oh, and for gosh sakes, don't mix color temperature fluorescent lamps in one room. I think that annoys me more than anything.

Re:Not sure this discovery is necessary

[rising_hope]

They produce light efficiently (not THAT efficiently) but don't produce that much light compared to a very simple single-bulb HID or fluorescent tube (by the way, which tube are you basing that "3x" on? T12, T10, or T8? Because T8's are MUCH more efficient that T12's). It takes a HUGE number of LEDs to replace ONE T8 fluorescent tube- and that tube costs a few dollars tops, because it is very easy to make. Right now, a single Luxeon white LED sells in 100-1000 unit quantities for well over $10-20, and produces 1-5W. A T8 bulb will produce 30-40W, and costs RETAIL about $5.

(1)Perhaps you should take a lesson from Apple on "performance per watt" being what matters. ;-) 5W of led power compared to 40W of Fluorescent compared to 55W of Halogen compared to 120W of traditional bulbs under your method would have you thinking that traditional light bulbs would produce the most light. The real unit of measure that matters is lumens. Yes, LED bulbs are expensive right now - but they're decreasing in cost RAPIDLY. A few years ago, White LEDs ran about $1/ea. These days, they're about $.16/ea. As cost continues to decrease, LEDs may eventually become cheaper than traditional bulbs.

They require new reflector designs and light spreaders, since they are a VERY small point source. A lot of work goes into making light sources produce even, smooth lighting that won't generate harsh shadows- point sources make this job a real bitch. Point source also means that despite relatively low heat output the heat is very localized, and that means PCBs must also be heat spreaders, complicating assembly/design/manufacture further. You can't just toss them on a PCB. Companies like Luxeon now sell them on little PCBs with the necessary spreader etc, but now you're not just talking about buying an LED, you're buying a whole assembly for your product...$$$.

(2)Certainly, custom housing adds to cost, but again, as demand ramps up, so will supply, costs will be offset.

Related- while they have a long life before failure, most of the high-output LEDs drop in light output very significantly, within a year or two of continuous operation 10-20 degrees above room temperature. VERY few LED manufacturers disclose this upfront- and virtually ALL the companies hawking LED products fail to mention this nice little caveat. Furthermore, just because the LED is rated to, say, 100,000 hours- doesn't mean it won't burn out because the company that made the device it is part of didn't botch the job on current+voltage regulation, heat dissipation, etc.

(3)Given that even the poorest made LED will probably outlast even some of the best made Florescents, I don't see where you're complaining. Also, you should check out the Forever LED bulb sometime. The manufacture offers a lifetime guarantee that the bulb won't burn out - ever. Sure, they bulb is $20, but that's trivial compared to the millions of traditional bulbs that'll burn out between now and forever. :-)

http://www.shop.com/op/aprod-p19829218?sourceid=3

I know everyone thinks they are the second coming of Christ, and they do have some wonderful applications (like traffic signals and car brake lights)...but they're not the end-all be-all.

Sure, they might not be the second coming of Christ, nor are they the end-all, be-all - but, they're probably the best lighting source available in modern times...

Re:Not sure this discovery is necessary

[Reziac]

I have a bunch of fluorescents; I hate them (they make everything fuzzy-edged, and they are painfully bright to my eyes) but with SoCal's outrageous electric rates, well, regular lights cost $30/mo. to run, and fluorescent about $8. I've had some since 1998, long enough that some have failed.

When they're new, they are relatively cool to the touch (compared to incandescent). However, as they age, they run hotter and hotter (they also get slightly dimmer with age, and tend to slide toward a less-annoying spectrum, with somewhat less blue skew). When they're close to failing, they get VERY hot.

I have some LED nightlights; their light is blue-white and not very good quality (fuzzy) compared to the ones that use an Xmas-tree type bulb. They only use 1/2W (vs 4W for the Xmas lights) but only produce maybe 10% as much *usable* light.

Re:Not sure this discovery is necessary

[Sleepy]

>Wrapping the point source in a simple translucent bulb qualifies as a "real bitch"?

If you allow for real world factors, yes. For example the translucent shell may reduce efficency by 20%.
It's not a roadblock, but it's one more disadvantage of LEDs in terms of manufacturing and economy, and one more source of cost.

I use flourescents, incandescents, and two LED sources at home. While I'd like to go all-LED -- the fact that these things wear down (less light) over time means eventually you're tossing them out, so you can't even think of these as one-time investments... yet.

Oh no!

[Trip Ericson]

But now we'll have to change our "how many x does it take the change a lightbulb" jokes!

"How many /. readers does it take the change a lightbulb? They don't have to because it's LED!"

Re:Oh no!

[Stripe7]

I already have too much LED lighting in my bedroom. LED's from my air ionizer, DVD/VCR player, Amp/Reciever, 3 computers, Tivo, HDTV reciever, Digital Cable box, UPS, ... red, blue, orange and green LED's. Who needs Christmas decorations, my home electronics supply more than enough garish lighting.

Re:Oh no!

[dotgain]

Or more to the point, how many lightbulbs am I going to have to change!?

Re:Oh no!

[Anonymous Coward]

"How many /. readers does it take the change a lightbulb? They don't have to because it's LED!"

Even with LED it takes 42...

Original Reference

[Anonymous Coward]

"This work is published online in the Oct. 18 edition of the Journal of the American Chemical Society."

No Effing Way!!!

[Anonymous Coward]

Have you ever tried an LED light? They suck!!! They do not cast nearly enough light. The light color is a disturbing and unnatural color, usually with too much blue in it.

Florescent tubes are FAR superior to LED lights and yet so many people prefer good old incandescent lights to even florescent tubes. Hell, even something as simple as a flash light. Try an LED flash light and then try a xenon Mag Light and tell me which one rocks your socks.

LED lighting is one of those technology "revolutions" that are for the sake of technology. They are NOT better.

Re:No Effing Way!!!

[Anonymous Coward]

I have a headlamp that has 4 white LED's in them, they shine pretty bright for over 80 hours on 4 AAA's. Enough to see a good 10 feet in front of me. I havn't seen any florescent or incandescent lights work that well for that period of time.

Re:No Effing Way!!!

[jsmucker]

Buttttttt they are improving at a pretty fast rate, so in another 3-5 yrs things will be differnt. ( think differnt )

Re:No Effing Way!!!

[billyj]

Consistant misspeling is a virtue.

Re:No Effing Way!!!

[nick8325]

Consistent misspeling is a virtue.

T,FTFY :-)

Re:No Effing Way!!!

[gkndivebum]

Yes, I have tried LED lights. I use them as backup lights for underwater (SCUBA) use.

While my primary light is HID, and I vastly prefer its color profile, the LED light offers long burn times (battery life), which is just what you want for a backup light.

Additionally, Luxeon Star (http://www.luxeonstar.com/) LEDs and improvements in reflectors are making LED lights more useful as primary lights as well. My wife carries a 4 watt Luxeon Star light as her primary light (in addition to her camera).

Re:No Effing Way!!!

[David Horn]

The reason LED lights appear blue is because we're used to white light (ie, from the sun) being slightly yellow, and correct it automatically. If you lived for a few weeks under LEDs alone, you'd quickly discover that they are in fact pure white light.

Re:No Effing Way!!!

[hardcorey]

I do a lot of outdoors activities, so I have had many flashlights and headlights. I must say, with no hesitation, my most recent lights, which have both been LEDs, have been far superior to any incandescent/halogen/xenon light I've tried. The first headlight I had had 3 LEDs in it, three brightness settings, and I never had to use it on anything besides low. My new one has 5 LEDs with similar brightness settings, and again I never have to use it on anything but low. Also, the battery life is much better on these, and they usually require fewer (and smaller) batteries than traditional lights.

Re:No Effing Way!!!

[Anonymous Coward]

Since you mention a blue color you probably haven't read the fucking article or ever seen the light they are talking about and have nothing to contribute but your narrow little tiny prick of an opinion on something else entirely. Gee thanks.

Re:No Effing Way!!!

[famebait]

Nope, it's because the cheap ones have really weird color spectra. If they could just as easily make them look good to most people at the same price, it would be a no-brainer to do so.

But I'm sure better ones will come along pretty soon.

Re:No Effing Way!!!

[julesh]

Have you ever tried an LED light? They suck!!! They do not cast nearly enough light. The light color is a disturbing and unnatural color, usually with too much blue in it.

Did you ... err ... even read the summary? This is about a new way of producing LEDs so that their colour looks more natural.

Try an LED flash light and then try a xenon Mag Light and tell me which one rocks your socks.

I have one of each here. Unfortunately, the xenon light weighs about twenty times as much due to the weight of its battery. It produces more light, but not enough more that I'm willing to forgive its shorter battery life. My LED light (which is actually a home-made one, with 24 high output LEDs in white and yellow) produces an adequate amount of light for off-road cycling, illuminating clear detail ~ 5-10 metres ahead of me, and has an 8 hour battery life from a pack of standard NiMH rechargeables.

They are NOT better.

Depends on the application. I also use LED lighting for low level lighting to leave on at night. It's perfect for this application as it has a narrow spectrum that isn't disturbing when I'm trying to sleep, but provides enough light that I am able to distinguish obstacles and move around the house without having to turn the main lights on.

Re:No Effing Way!!!

[serverslayer]

"The light color is a disturbing and unnatural color"

Once again life imitaiting art, Half-life 2's lighting engine will take a sudden leap towards more realistic lighting with the widespread use of LED for home/office/*tunnel* use.

Re:No Effing Way!!!

[Anonymous Coward]

Buttttttt they are improving at a pretty fast rate, so in another 3-5 yrs things will be differnt. ( think differnt )

But you are assuming that incandescent technology is standing still! Incandescent light bulbs today are 50% more efficient than just 10 years ago.

Re:No Effing Way!!!

[StikyPad]

Consistent misspelling is a virtue.

IHNIWYAM

The greatest discoveries...

[PGC]

are not followed by 'Eureka' , but by "Hey, that's funny" .

Re:The greatest discoveries...

[ehiris]

Who should I credit this quote to?

Re:The greatest discoveries...

[B-a-Z.nl]

Let's quote the source on that now shall we?
Isaac Asimov
"The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...'"
http://en.wikiquote.org/wiki/Isaac_Asimov

Re:The greatest discoveries...

[moviepig.com]

The greatest discoveries... are not followed by 'Eureka', but by "Hey, that's funny".

...and used to be shown as a light-bulb going off. But now I guess that's out...

Schroedinger's Bulb

[dada21]

If I close my bedroom door, my quantum bulb will neither be working nor burnt out.

Re:Schroedinger's Bulb

[ehiris]

Depending on who is observing the light might be off or the light might be on.
It's actually really good when you have a hot girl over and you want the light on while she wants the light off.

Re:Schroedinger's Bulb

[DJCater]

Stick with the cat analogy. Slashdotters won't know what 'having a hot girl over' means.

Re:Schroedinger's Bulb

[G-funk]

And then you tell her your best schroedinger's LED joke, and her quantum state becomes both sleepy and scared?

about time.

[CDPatten]

I can't wait until the day the masses move away from the traditional light buld. I have moved the majority of my home/office lights to leds with a combination of light tubes. I still use the traditional, but not as much, and usually for its warm glow, then its raw lighting effect.

Re:about time.

[Fishead]

My 300Watt Halogen Torchier just burned out the other day. I have it at the back of my desk, projecting onto the ceiling. With a dimmer installed, it makes the PERFECT light for using the computer.

When it burnt out, I had to resort to white Flourescent, or a 100Watt Incandescent bulb.

I gotta tell you, it SUCKED.

There is something to be said for having a soft, warm light that doesn't flicker like Flourescent. I couldn't wait to get back my "energy offender" bulb!!!

Screw efficiency, Halogen torchiers still produce the most comfortable light that I have ever seen.

If they could mimick the colour of Halogen using LED's, THEN maybe the masses and I will move away from the "traditional light bulb".

Oh, and LED Christmas lights SUCK. I hope my whole block switches to them so that my house will have the best looking lights without me doing any work.

Re:about time.

[CDPatten]

I strongly agree with you, well about the mood stuff. I engineered my house to be energy efficient (goal when I'm done is to be completely off the grid), and LED fit the mold. I actually use fiber optics for allot of my lighting, well accent lighting, etc. The areas where I use the most Edison bulbs is in my lab/office... like you said, it's the best working light.

That said, if the article is correct, we will get the best of both worlds pretty soon, for pretty cheap.

well, likely not.

[way2trivial]

at my workplace, a hotel on the beach.

We had for many years yellow colored standard bulbs, as they don't attract bugs.

we started replacement with yello fluro twist bulbs, to save on electricity and replacement costs.

in research, it turns out, we can use white fluro-- as they only emit light in a very narrow spectrum of white light, unlike an ordinary filament bulb.. and the range they do emit light on, suitable for humans, does not attract bugs.

I'd guess these low power led lights also emit white light on a very narrow band....

Re:well, likely not.

[Anonymous Coward]

a narrow spectrum of white light? eh?

Re:well, likely not.

[advocate_one]

a real contradiction of terms there... ;) I'm convinced science education has gone down the tubes... and this is really basic stuff which should be done in junior school...

Re:well, likely not.

[way2trivial]

alright, it has the white light, and none of the 'rest' of the spectrum, which apparently attracts bugs.
but yes, a narrow spectrum of white, I found a good picture here
http://www.truesun.com/Litetube.htm

roll down to where there are three bulb types listed.

note the incandescent bulb rolls up from blue to red
note the fluroscent has three spikes of blue, yellow and red

the missing bits, including the missing UV and IR at the ends, include whatever attract bugs.

so yes- a narrow band of white light......

Re:well, likely not.

[farquharsoncraig]

http://exploration.vanderbilt.edu/images/news/arti cle_main/quantumdot_led_5.jpg

Re:well, likely not.

[Anonymous Coward]

I have some of those Yellow bulbs you are talking about, and let me tell you, these Tennessee moths LOVE them more than regular white bulbs. It just doesn't make sense.

I guess these country moths evolved to like whatever light was available.

Re:well, likely not.

[Nicolas MONNET]

It's probably the infrared and near infrared that attract bugs.

Re:well, likely not.

[Weedlekin]

More likely UV, which many insect eyes are sensitive to, hence the fact that many flowers reflect UV very efficiently, and bug-zapping lamps use actinic light tubes.

Re:well, likely not.

[Reziac]

Please inform the bugs in my neighbourhood, which are attracted in swarms to the plain white fluoresecent bulb that lights my porch. Several toads and preying mantises make a permanent home on my porch, ecstatic over the eternal bounty.

From the FAQ on LEDs

[jkind]

Answer: there are several obvious advantages LEDs have over traditional incandescent light bulbs, they are as follows:
Low power consumption - energy saving,
Long lasting,
Cold lighting,
Ruggedness,
Small size and weight,
Fast switch times,
Simple to use.
This is from the FAQ, but it doesn't list any disadvantages..
anyone care to share?

Re:From the FAQ on LEDs

[loyukfai]

I think it's the initial procurement cost, high brightness LED are much more expensive than traditional bulbs.

Re:From the FAQ on LEDs

[Rob the Bold]

Some Disadvantages:

Like Fluorescent, requires supporting circuitry -- doesn't plug directly into AC wiring.
Cost (initial investment)
Harder to dim -- can't use simple rheostat
Flicker (if using less than 100% on time)

I don't have anything against LED lighting, and none of these disadvantages are insurmountable. Indeed, these could be viewed as business opportunities instead. Most of the disadvantages are shared with fluorescents, and adequate solutions already exist there. I know a guy who lights his whole off-grid house with LEDs (using low voltage DC wiring). I particularly like the possibility of creating variable color lighting with LEDs, emulating daylight, sunlight, tungsten or whatever.

Re:From the FAQ on LEDs

[MadScientistVX]

They are not quite as cold as people think. My dad has a 3 professional 1-3 Watt LED flash lights and although the light to heat ratio is great compared to traditional flash lights (not to mension, the quality of light is much better) It still emits a significant ammout of heat, which will become more evident as LEDs are used on a larger scale.

Re:From the FAQ on LEDs

[norminator]

From a senior project I did in a few years ago, we dimmed an array of 300 high-powered LEDs (Lumileds)with no flicker at any level. They definitely didn't run totally cool, though they did have a fair amount of heat. As far as dimmers go, most standard dimmers use SCRs or triacs for dimming instead ofa rheostat anyhow, and that should work just fine for LEDs. Whatever supporting circuitry is used can easily provide dimming capabilities already built-in.

Re:From the FAQ on LEDs

[fermion]

Presumable one would build an array of LEDs onto an array, presumably with an integrated diffuser. One could create the actual devices in clusters, of say N leds, and then array the clustered. Each array would have the logic to turn on 0-N leds based on input voltage.

The problem is that flourescents are not popular enough, even with the new cofigurations. There are no decorative florescents. The light from flourescents is sterile. With LEDS one could theortically tune the light to match the applications, and configure enclosures to arbitrary shapes. LEDS may not be better from a consumption point of view, may be more enviromentally destructive to manufacture, and cost more, but that will balanced against a much more versitile device that has an extremely long MTBF.

Re:From the FAQ on LEDs

[julesh]

Like Fluorescent, requires supporting circuitry -- doesn't plug directly into AC wiring.

You can connect LEDs directly to AC if you want. They'll flicker, but if you connect two sets in parallel but with opposite polarity, it generally isn't noticeable. You can even build a bridge rectifier from them.

You'd still need a transformer to bring the voltage down to something useful, but that's nothing like as complex as the support circuitry required for a flourescent.

Mind you, the cost of compact flourescents with integrated support circuitry has come down substantially in the last few years. I'm now able to get 9-17 W CF "bulbs" at about $1 per unit.

Re:From the FAQ on LEDs

[njyoder]

Are you insane? If you connected them directly to your outlet they'd burn out instantly. I've burned out LEDs by accident with much less current, so I don't thinkt hat's a valid argument.

Re:From the FAQ on LEDs

[deathazre]

bridge rectifier would count as supporting circuitry.

And without some sort of current limiting circuitry, an LED on AC will either be on for a very small duration at the very peak of the waveform, or will draw far too much current when the voltage rises too far above the voltage drop of the LED.

It's all LIES

[Anonymous Coward]

So light makes them glow? Why is there no feedback loop here?

Re:It's all LIES

[Anonymous Coward]

Oh, there is feedback, it's just not mentioned. These things are just like an perpetual motion machine, but for light. If a room if painted with these quantum dots, then the room is dark until it's started with a camera flash, and that's it, light forever!!

We'll need a replacement for the Goodyear Blimp!

[Anonymous Coward]

A LED Zeppelin, of course.

Good ole MSNBC...

[k31bang]

From TFA:
LEDs don't emit heat, so they're also more energy efficient


*cough* *cough*

Re:Good ole MSNBC...

[ElitistWhiner]

At least there is one /. poster who knows the efficiency of LED lighting is only popular myth. They consume the same power but last forever.

Re:Good ole MSNBC...

[loyukfai]

I'm not sure if LED "emits" heat but AFAIK, it does "produce" heat, and that's why LED torches need heatsinks because the performance of LED is negatively related to the its temperature.

Or it's something else?

Re:Good ole MSNBC...

[hydopower]

Thermodynamics, man. I would be pretty interested in seeing basically anything that didn't emit heat while it's emitting a lot of light.

Spelunkers Joy

[joey_knisch]

About 7 Years ago I brought a LED Headlamp to a spelunker convention. They were leery at first but when I didn't change my batteries once during the entire weekend they were sold. The next year there were about 10/50 of us on LED. Now everyone has an LED lamp.

Re:Spelunkers Joy

[geekyMD]

Are you serious?

Perhaps I'm missing something, but I had a great change to demo several LED vs incandescent headlamps while spelunking in Belize recently.

The LED users (including myself) never had to worry about batteries, and their surrounding 20' lit up well. However their field of view was un-naturally gray and colorless, like the moon, and depth-perception was impaired). Beyond that, you could see ABSOLUTELY NOTHING with an LED. Its like the world just didn't exist, no reflections, nada. If I wanted to see the flowstone 20' in front of me, I had to pull out the maglight.

The Incandescent users brought an extra couple sets of AAA's just in case, but they had great depth of field, and the colors of various mineral formations were vivid and clear. Best of all they could see formations over 100' away without busting out any special equipment. The weight they carried with extra batteries was less than the extra flashlight I had to carry.

IMHO LEDs are great for around basecamp or just fudging around or even for torches for tables, but if I'm repelling of a cliff in the dark of the earth, please oh please make my headlamp an incandescent.

What am I missing that makes everone else want these things?

FTFA

[Associate]

When a brilliant idea pops into your mind in the future, what will appear over your head?

Answer: $$$

Re:FTFA

[xigxag]

I think you mean:

RMB¥ RMB¥ RMB¥ :P

Ideas of the Future?

[Garridan]

"One big question remains: When a brilliant idea pops into your mind in the future, what will appear over your head?"

Smoke. That's one thing that I don't see changing any time soon. Not for me, anyway.

Re:Ideas of the Future?

[richdun]

Oh, I'm sorry, the correct answer was "an IP lawyer", "an IP lawyer." Well, thanks for playing! We have some wonderful parting gifts for you.

Re:Ideas of the Future?

[Anonymous Coward]

"One big question remains: When a brilliant idea pops into your mind in the future, what will appear over your head?"

Smoke. That's one thing that I don't see changing any time soon. Not for me, anyway.

Or if you are in a cartoon and your name rhymes with Riley, an anvil.

Re:Ideas of the Future?

[Reziac]

It's time to change your bulb.

maybe, but here's a way better article

[farquharsoncraig]

http://www.google.com/search?q=Michael+Bowers+Vand erbilt+University

http://exploration.vanderbilt.edu/news/news_quantu mdot_led.htm

Re:maybe, but here's a way better article

[mikiN]

First off, that's a good link. Second off, maybe the submitter of the original article intentionally linked to MSNBC because it is a site with a big badass server farm, so as not to cause a Slashdotting of the Vanderbilt server.
People who read Slashdot and are really interested in this subject probably know how to use Google to find the main article (and its link to the publication in JACS).
Lucky for you, this time Google has already cached the main article...

Re:maybe, but here's a way better article

[Anonymous Coward]

Don't worry - Vanderbilt's pipe and hardware are more than capable of withstanding a random Slashdotting. Now, if someone dropped this on Fark at the *same* time, that might be an issue ...

Re:maybe, but here's a way better article

[farquharsoncraig]

True, I had not thought of that at the time. However, as you imply the first thing _I_ did was go to google. (-: However, university servers are probably better able to handle the slashdot effect better than Joe Gradstudent's budget webserver.

Thinkgeek

[Eightyford]

I'm totally surprised that they OSTG didn't pimp their LED bulb from thinkgeek. 35 bucks is a little steep though.
http://www.thinkgeek.com/gadgets/lights/7aa8/


Of course, you could always make your own.
http://www.etgtech.com/update/products/super_flux. htm

Re:Thinkgeek

[Anonymous Coward]

Wait. Wait. You're surprised they didn't pimp it, so you went to extra trouble to include a link? Are they paying you? :-)

Score: -1, consumer whore pimping OSTG products

Think of the cartoons

[obli]

This'll totally screw it up for the cartoons who use the light bulb as a symbol for an idea, I hope you feel guilty...

LED efficiency versus Compact Fluorescents

[lancejjj]

This could be a big advance for LEDs. But as of now, commercially available LEDs do NOT produce as many lumens per watt as Compact Fluorescent Light bulbs (CFLs.) Of course, this new LED discovery may improve LED efficiency to the point where they exceed CFL efficiency. We'll have to wait and see.

CFLs are inexpensive and readily available today. CFLs have a long life, and they save a ton of energy when compared to traditional light bulbs. Even more importantly, they don't suck like the CFLs of a few years ago that had a noticeable/painful "warm up" time.

I save quite a bit off of my energy bill by using CFLs. They really cut down on electricity consumption, and I've never had one "burn out" on me. Ever. Yet.

Re:LED efficiency versus Compact Fluorescents

[dr_db]

CFL's do not like enclosed fixtures - I live in a rental, so I am not inclined to change them, but *every* cfl I put in those fixtures failed. I did post-mortens on them, some seemed to have unsoldered themselves (wires off the board) and others just seemed to have died. They never seemed to feel hot enough to melt solder, but the conditions in the base while running might have been pretty rough. So 15 have failed, 2 survived (in open socket applications). Many rooms in my house have regular tube fluorescents, which rarely give me trouble.

Re:LED efficiency versus Compact Fluorescents

[King_TJ]

Yep! I've had the same experience. I have a couple of enclosed fixtures in my kitchen with 2 bulbs in each, and thought "Hey - I can really save some $'s going with CFL's in these!" - but they all failed in a matter of 1-2 months of occasional use. A couple of the CFL's I removed even had brown burn marks on their white plastic casings.

I've had another one just in an open socket in my basement that started misbehaving due to what seems like a loose connection inside it. It intermittently goes out and I can bring it back to life by tapping on it.

I like the energy efficiency of them, but considering their much higher iniital cost compared to regular bulbs, they're not really going to save me much if they keep failing. So I'm done with using them in any kind of enclosed fixture. (The "not recommended" warning on their boxes isn't kidding, folks!)

Re:LED efficiency versus Compact Fluorescents

[lancejjj]

CFL's do not like enclosed fixtures - I live in a rental, so I am not inclined to change them, but *every* cfl I put in those fixtures failed

Some CFLs are designed to work in fully-enclosed fixtures.

I too live in an apartment (and I pay for my own utilities). I replaced the incandescences with fixture-rated CFLs... and again, no failures after 3+ years.

Your mileage may vary. Reliability might depend on the manufacturer or ambient temperature (I live in the north).

Re:LED efficiency versus Compact Fluorescents

[dr_db]

I didn't know that. I have bought bulk from Ikea, and I bought many packages of philips. None said anything about being fixture rated, or had a not-recommended warning printed anywhere on the packaging, or bulb itself.

I'll have to look into that, as I have kids that love to leave the lights on all over the house, and I would love to not pay bills while I switch-train them.

Re:LED efficiency versus Compact Fluorescents

[lancejjj]

Oh yeah, several CFL models I have do in fact discourage against enclosed fixture use, while others say it's OK. And still others have, sadly, no markings.

My three Ikea CFLs (bought about a year ago) are used in a vented ceiling fixture... so I have no idea how they'd perform in an enclosed fixture. I don't believe they had any statement regarding appropriate use.

I have some LightWiz CFLs (I think) in my four enclosed (and seeming airtight) 1950s-vintage ceiling fixtures. One fixture takes two bulbs - the others three take one bulb. In all of my fixtures the bulbs are mounted horizontally. Hope that helps.

Re:LED efficiency versus Compact Fluorescents

[falconwolf]

They really cut down on electricity consumption, and I've never had one "burn out" on me. Ever. Yet.

I've just had one burn out, however of those I have now the oldest one is several years old. Whether it's the oldest I don't know but the last one I bought I got a few years ago. I've been wondering if I'll start to replace them with LEDs, I read several months ago about them.

Faclon

Re:LED efficiency versus Compact Fluorescents

[cheekyboy]

I cant see CFL saving much for me, i dont use lights might at all.

Bath rooms - 2-5mins max at a time
Bed Room - 10 mins max at once
Kitcken - thats circular CFL
Lounge - rarely have the lights on, just the tv and a side table CFL or ambient colored lamp
Hall - might be used often, but again its only a 40watter there

Old news

[karvind]

Can anyone explain me why is this a new news ? Earlier demonstration by Sandia labs.

*shrug*

Costly Quantum Dots

[ObligatoryUserName]

If the manufacturing breakthough talked about in this article pans out, the cost of Quantum Dot manufacture will drop from $2,000 to $400 per gram. That's huge improvement, but I still wouldn't expect to see Quantum Dot lightbulbs on ThinkGeek anytime soon...

Re:Costly Quantum Dots

[fermion]

The cost is key. Flourescents tend to be expensive, and even though one can recoup the cost on longevity and power savings, and for large installation labor costs, for the common person the stickeer shocks pushes us back to incadescents. Combine with the 'institutional' reputation of flourescents, and the lack of pretty shapes, and one sees that the market for alternative lighting will be small.

There may be one saving grace. If LED lights are available, then new houses might be designed with the indirect lighting that has been theorized since before Heinlein crafted his first tome. And if the lighting lasted the normal lifetime of the electrics, say a MTBF of 10K hours, then it could be considered a durable item that is just replaced by a profesional. And the house will have a better energy rating, as the lighting will consume less power and generate less heat per lumen.

Re:We'll need a replacement for the Goodyear Blimp

[Pfhorrest]

Oh come now, that was highly uncalled for. Puns are for children, not groan adults.

(Note to mods: that's not a spelling error).

Just a few disadvantages of LEDs

[Anonymous Coward]

Disadvantages include:

Low candle power. LED lights are lacking in their production of, well, light.
Unnatural color. LED lights have unnatural and sometimes disturbing colors. Incandescent lights have a warm glow that is closer to natural light and "full spectrum" incandescents produce something very near sun light.
Expense! Producing an LED "bulb" with the same candle power as an incandescent bulb is FAR more expensive than the incandescent.
Possible health issues due to the poor light quality. A plant will grow under incandescent light, it will not grow under an LED.

Re:Just a few disadvantages of LEDs

[roseblood]

Incandescent lights have a warm glow that is closer to natural light and "full spectrum" incandescents produce something very near sun light.

Hell no. Incansedcent lights are ORANGE.

Every grab a color corection filter to shoot daylight films under incandescent light? It's cyanish blue. Wonder why when you shoot with the INDOOR color balance setting on your digital cameras photos you take outside look blue and photos indoors shot on the outdoor settings look orange? Because incandescents are NOT the same color as daylight.

But, agreed, artifical light (most of them) are unnatural in their color. Even daylight balanced flourescents are not full-spectrum daylight balanced lights.

A return to white street light

[Simonetta]

One of the unfortunate side effects of the 1970s was the replacement of all the soft white street light bulbs with orange-yellow sodium vapor bulbs. Sodium vapor bulbs use less energy. All the night lighting went from soothing soft white to light orange. Orange, as you may recall, is the color of madness.

    I've never liked yellow-orange streetlights. It's one of those things that never gets noticed. But the difference can be really appreciated if you go to a wealthy neighborhood where white light bulbs are still used. However, unless you're older and white, it's going to be a short time before the 'security guards' drive up with tasers and ask you what you're doing. If you're truthful and tell them that 'you're digging the cool white groove of the light, baby', then they will do what all mercenaries do when encountering a civilian harmlessly enjoying life, they will kidnap and assault you for their amusement.

    Anyway, a return to soft white lighting in the night will be most welcome.

Re:A return to white street light

[Anonymous Coward]

Where can I get some of whatever it is you are on?

Re:A return to white street light

[Anonymous Coward]

OT, but I don't like yellowy-white lights either, they look pretty grimey and rough to me. Maybe something happened in the past that I don't recall which makes me associate yellowy light with it. I like the bluey-white (and almost pure white) car headlights, but not the yellowy-white ones.

Re:A return to white street light

[Yartrebo]

Even if these new bulbs were free they wouldn't replace low pressure sodium bulbs.

A 60W incandescent bulb is the bottom of the barrel in efficiency. If this thing is twice as efficient, then it would fall in between halogen bulbs and standard fluorescent bulbs in efficiency. Compact fluorescent bulbs are 4-5x as efficient as 60W incandescent bulbs. Low pressure sodium vapor lamps are something like twice the efficiency of fluorescent bulbs, and for something where the light is used only a fraction of the time it's on and draws very large amounts of juice, I would rather they be energy misers, so my taxes can be kept low and I can spend the money on better indoor lighting, which I am around much more than street lighting.

BTW, for indoor lighting, compact fluorescents already put out a very nice light. I don't see any need to switch to a bulb that is half as efficient, even if it does last several times longer. They're also dirt cheap. My last batch cost me only three bucks a bulb.

Re:A return to white street light

[Anonymous Coward]

sounds like he's just depressed. you may not want that

Re:A return to white street light

[DJDutcher]

There is another advantage to the yellow orange high preasure sodium lights. They aren't as big of a problem when it comes to light polution, because it is easier to filter their narrow spectrum. That makes astronomers happy because they can put fitlers on their telescopes. A lot of dark sky advocates will ask people to switch to high preasure sodium, if they have to have a light.

I know what you mean though. I do hate the way they look. The orange glow even makes trees look creepy.

Re:A return to white street light

[Gordonjcp]

They've just started replacing all the orange streetlights with white ones here (not-wonderful part of Glasgow, in Scotland). It does look good, and it's a lot easier to see pedestrians and cyclists when you're driving at night.

There is a bit of a weird green glow where they shine through trees, though.

Re:A return to white street light

[advocate_one]

at least I can filter monochromatic sodium light out from my telescope and binoculars... but ordinary white streetlights are a much bigger pain when it comes to destroying the night sky views...

Re:A return to white street light

[thomasa]

I disagree with your like. I find the white lights to be over
bright and obnoxious. I much prefer the muted look of the
sodium vapor lights. Especially from the air. The yellow
lights are much more pleasant to view. What would be really
nice is if we could change them to our liking. I have one
of those bright white lights in the street outside my house.
If it had knobs on it where I could change its spectrum, that
would be cool. My ex-wife's neightborhood has no street
lights at all - which I really prefer.

Re:A return to white street light

[toddestan]

A lot of dark sky advocates will ask people to switch to high preasure sodium, if they have to have a light.

Actually, astronomers want the low pressure sodium, as low pressure sodium only emits strongly in two very close wavelengths of yellow light. High pressure sodium has a much broader spectrum due to the doppler effects of the gas inside the bulb, making it harder to filter. On the other hand, the broader spectrum of high pressure sodium makes the light not quite so creepy, which is why many cities are slowly switching over.

Re:A return to white street light

[bogjobber]

My ex-wife's neightborhood has no street lights at all - which I really prefer.

Yeah, that's pretty creepy.

Re:A return to white street light

[glesga_kiss]

They've just started replacing all the orange streetlights with white ones here (not-wonderful part of Glasgow, in Scotland).

I have a sneaking suspicion that you live just round the corner from me. Mine got switched on just this week and I was finding it a little wierd that people were talking about this sort of thing here. Then you come along... ;-)

It's definitly a big improvement.

Re:A return to white street light

[Gordonjcp]

Kingsway flats, overlooking BaE. Sod it, take a guess and whois me ;-)

They got done a couple of months ago now.

Re:A return to white street light

[glesga_kiss]

Ah, cool, think I know where you are. I'm a little further down Dumbarton road, Partick. Small web...

I've yet to see how the white tracksuit brigade take to the new light. I reckon their feral instincts will push them to seek darker climbes, which should be good for the indigenous population! ;-)

Re:A return to white street light

[markotime]

The yellow peril Sodium vapor lights have a huge advantage here in the rainy
Pacific Northwest - the pavement becomes visible, as do pedestrians, deer, pets, potholes and lines. But both low and high pressure Na vapor lights can be used, one being a lot less offensive to sky watchers (and I'm one).

Re:A return to white street light

[Reziac]

See above where I talk about how yellow sodium lights make my light green truck completely invisible at night.

In SoCal, most new street lighting is of a pinkish shade (I don't know what type it is; I do know it appears more yellowish to people with average to poor colour vision. I have that freaky extra-keen colour vision, and I tell you, it is more pink than yellow.) Not only is it ugly, the light pollution produced by these lights is several times as bad as that from ordinary traditional white streetlights.

Furthermore, even to folk like myself with very good night vision (I'm often accused of being a vampire :) the useful quality of this pink light isn't as good as traditional street lighting; the pink lights put a fuzzy edge on everything. This in fact was a common residential complaint when they first came into use in Great Falls MT, back in the late 1960s.

Re:A return to white street light

[Reziac]

I totally agree with you. The yellow and pink street lighting of the present is ugly, and not as effective as the old traditional white lights.

Pink lights were first used in Great Falls MT ("The Electric City" because unlike most places where there were only corner lights, GF had three per block) in the late 1960s, and complaints from residents were rampant. But they were "better" so they stayed.

I still hate them. And relative to the visual usefulness of the light they produce, these newfangled lights simply don't work as well as the old white lights, AND they produce more light pollution for the same amount of *useful* light.

Re:A return to white street light

[Gordonjcp]

Hahaha... They're too busy setting each other alight with fireworks this time of year.

I used to live in Partick, right opposite the police station. Moved about 18 months ago. Small world indeed.

Re:A return to white street light

[Anonymous Coward]

Nigga heard dat one loud 'n' clear, mo. I keeps mah ass outta dose hoods now. Nigga aint going back ta prison. Shit.

"Accidental invention could light up the future"

[oskard]

Aren't they implying that most inventions are accidental then? Did he accidently hit the 'shine laser' button? Hm..

Current LEDs are not there yet

[The Optimizer]

I just finished converting the lighting in my house to save energy, and learned a few things in the process. Most of the incandescent bulbs were replaced with compact fluorescents, but I did install 4 LED light bulbs in one application.

The current generation of compact fluorescent bulbs has come a long way from the ones I remember 10-20 years ago. They don't have the flicker or startup problem anymore, and they are available in a variety of color temperatures from 2700 degrees (yellowish, comparable to incandescent) to 6100 degrees (white, sterile). For the same light output (lumens), energy consumption is normally 22% to 27% of the incandescent bulbs they replace. They very slightly in things like color and wattage depending on the manufacturer.

Nobody who has visited my home has yet noticed the difference.

Since you can find common CF bulbs sizes for under $2 per unit (try Sams Club, etc), and they should last 4 to 8 times as long as an incandescent, the economic case is pretty sound even before factoring in the energy savings.

I replaced 4x 7.5 watt bulbs with LED bulbs and noticed a few things. The LED bulb itself is about twice as large, and as others have mentioned, the light emitted is an eerie blue-white light. You defiantly notice it. These bulbs consume 0.8 watts and produce an output pretty close to the 7.5 watt bulbs they replaced, though I could not find the output in lumens for either bulb anywhere. They were about $7 a bulb, and are rated to last 100K hours, or about 50 times as long the bulbs they replaced. Since the bulb is actually made of up 18 individual LEDs inside, I believe the rating is for the mean time until 50% of the LEDs are no longer functioning.

After converting 152 of 160 bulbs in my home, my electric bill happy.

Re:Current LEDs are not there yet

[barjam]

I put a couple compact fluorescents in the garage hoping I wouldn't have to replace them as often (hard to reach) but for some reason they lasted only about half as long as a regular bulb.

*shrug*

Re:Current LEDs are not there yet

[DJCater]

>eerie blue-white light

Is that not just because we're used to yellow-white light?

Re:Current LEDs are not there yet

[travail_jgd]

CFLs can be really sensitive to dirty or corroded fixtures. I've heard that bad fixtures and dimmers are the fastest ways to kill them.

Are the bulbs on a timer of some kind?

Re:Current LEDs are not there yet

[tylernt]

Were they placed horizontal or base-up? When CFs are installed base-up, the heat from the bulb rises and tends to cook the ballast, shortening lifetime. They do a lot better in base-down or horizontal installations.

I have a huge 45w (200w equivalent) CF in my garage. Going on 3 years, still works great. And it's even base-up.

I've had a few CFs burn out within a few months, too. I think some of them just have manufacturing defects.

Re:Current LEDs are not there yet

[Anonymous Coward]

Is that not just because we're used to yellow-white light?

Yeah, you know, like from the Sun.

Re:Current LEDs are not there yet

[Anonymous Coward]

160 Bulbs

160 Bulbs !!!

How the hell do you end up with 160 bulbs in a home? You must have tiny bulbs all over the place to run up that kind of a total - each with it fixed costs of manufacture and transport.

Think about revising your lighting approach and not only can you cut the energy/cost of each bulb, you can cut the waste of having too many multiples of the mounting, ballast, socket, wires, switches, transport and manufacturing.

Re:Current LEDs are not there yet

[Anonymous Coward]

The CFL light is far closer to the output of the sun than an incandescent.

Re:Current LEDs are not there yet

[Ben Jackson]

Another thing I like about compact fluorescents is the reduced heat. We have some ceiling fixtures that take 2 bulbs under a glass dome. If you put two incandescent bulbs in it's survival of the fittest. The extra heat kills the weaker bulb and you live with dim light until you replace it. Two CF bulbs are perfectly happy in there.

Re:Current LEDs are not there yet

[DJCater]

Is the idea of a light not to enable us to see rather than replicate the light from the Sun?

Re:Current LEDs are not there yet

[Anonymous Coward]

> After converting 152 of 160 bulbs in my home, my electric bill [is] happy.

Now you're going to have to tell us which 8 bulbs you didn't replace (and why).

Re:Current LEDs are not there yet

[deglr6328]

"They were about $7 a bulb, and are rated to last 100K hours, or about 50 times as long the bulbs they replaced. Since the bulb is actually made of up 18 individual LEDs inside, I believe the rating is for the mean time until 50% of the LEDs are no longer functioning."

The individual leds themselves will actually probably 'never' totally fail. The 100K hours refers instead to the time it will take brightness to decrease by 50%.

Re:Current LEDs are not there yet

[Anonymous Coward]

How the hell do you end up with 160 bulbs in a home?

150 of them formed a string of christmas decoration lights...

Re:Current LEDs are not there yet

[raygundan]

I've got well over 30 installed, replacing everything except a set of dimmable G30s in the bathroom. (Anybody have a source?) I've only had three burnouts. Two turned out to be a reverse-wired socket-- the incandescents don't give a crap about polarity, but apparently, some CFLs do-- I had two die in the same socket within just a few days. The other lasted a couple of years (around 3), but finally gave up. It was mounted base-up. Most of the bulbs in the basement have been with me since college, around 1997. All the rest just keep on kickin'.

Re:Current LEDs are not there yet

[David Off]

I have done the same in my house, although we have far fewer bulbs than you. We have a mix of 75w equivalent (15w real consumption) and 60w equivalane (11w real consumption). There is a difference in quality. Zenith are good and we also have some by a no-name manufacturer. Both start up instantly and, as you say, no-one has noticed the difference although best not to have the bulbs exposed. We have some other bulbs - paid less than a Euro (1.20 dollar) and they turn on instantly but take 5 minutes to reach full brightness - they are used in the hall.

We also have some legacy halogen bulbs which seem quite efficient.

Really if you intend staying in your home 5+ years go fluorescent.

In Europe LED's are heavily used in traffic lights and some car / motor cycle rear lights and of course they have been a godsend to cyclists where power consumption has always been at a premimum (the UK government recently legalised them for bicycles). Oh... and of course Japanese hi-fi manufacturers love them!

Re:Current LEDs are not there yet

[antispam_ben]

... incandescents don't give a crap about polarity, but apparently, some CFLs do

Huh??? Since lamp sockets are AC, this can't be true. There is no 'polarity.'

I had two die in the same socket within just a few days. The other lasted a couple of years (around 3), but finally gave up. It was mounted base-up.

FWIW, I've read that going through many on/off cycles can reduce the life of CFL's.

Re:Current LEDs are not there yet

[Anonymous Coward]

Nobody who has visited my home has yet noticed the difference.

*sigh*

Please don't call me for tech support. It is hard to help someone who makes unwarranted leaps.

Better you should say "Nobody who has visited my home has yet commented on the difference."

Re:Current LEDs are not there yet

[Baron_Yam]

It's never made sense to me either, but there is a polarity to A/C... and if you wire it incorrectly, some electronic devices will erroneously detect a line fault. I had it explained to me once, but the explanation just didn't stick well enough in my grey matter.

I learned about this when I got my first UPS and couldn't figure out why it had a red error light lit up. I learned about it again last year when my father wired a new basement and had to redo it because it wasn't to code for the same reason.

Re:Current LEDs are not there yet

[David Rolfe]

Is the idea of a light not to enable us to see rather than replicate the light from the Sun?

Maybe for some people (non cave dwellers, non geeks) the light from the sun is comforting, and thus desirable in their homes. Anecdotally, I can recall plenty of research going into the the manufacture and installation of light-pipes (fiber-optics, translucent concretes, etc) into large buildings because the full spectrum lighting produced happier workers/customers and drives down the incidence of seasonal depressive disorders (along with the benefits of energy-savings -- google it if you care).

I'm no expert, so I can't definitively say whether it's nature or nurture (as you postulate), but it seems physiological. The human animal responds (consciously and unconsciously) to sunlight differently from other light types.

Pardon any typos. Cheers.

Re:Current LEDs are not there yet

[Anonymous Coward]

It's not that one wire pushes electrons for half of the cycle, then the other wire pushes electrons the opposite direction. What happens is one wire pushes for half of the cycle, then pulls for the other half.

A fine distinction but it does make a difference.

Re:Current LEDs are not there yet

[Anonymous Coward]

There's a simple way to determine the existence of polarity in A/C. If you stand on the ground and touch the white neutral wire, nothing happens. If you touch the black hot wire, you get a nice shock.

Trust me, there's polarity. :)

no, it is NOT a contradiciton

[way2trivial]

I can make white light by emitting everything from UV to IR

or I can combine a 3 beams each of a very precise wavelength of red green and blue, and end up with WHITE.

a narrow spectrum of white.
very perception based.. I may see it as pure white, you may be more sensitive to one of the three, and therefore see it as green or blue or red tinged.

a bug may not see it at all.

Re:no, it is NOT a contradiciton

[tonsofpcs]

That isn't white, that's an overbrightness of the red green and blue that makes you perceive close to white, it is still not white.

Re:no, it is NOT a contradiciton

[dgatwood]

That's not true. At any brightness level, an equal combination of red, green, and blue will be perceived as white. It doesn't have to be "an overbrightness".

There are an infinte number of white light spectra. You seem to be defining it very narrowly as an incandescent white, but that is not the standard definition of the term.

Re:no, it is NOT a contradiciton

[Anne Thwacks]

Genetically, the spectral sensitivity of the red, green and blue comes in a number of different versions. The most common set of spectral responses for women is not the same as for men (In any case 10% of men are colour blind)

Thus it is possible to have light which appears white to a group of men, but not to a group of women.

Even more troublesome, it is possible to have two objects which appear the same colour to one group of viewers under two different light sources, but appear different colours to another group!

So when your girlfriend doesnt agree with your choice of colour scheme, there is a sound physical/biological explanation. And changing the girl probably won't help you!

Re:no, it is NOT a contradiciton

[utnow]

If you percieve it as very close to white, then for the purpose of a lightbulb in a room.... it's white.

You don't need a PhD to get that.

Re:no, it is NOT a contradiciton

[InvalidError]

If you have an RGB source with narrow-band 650nm red lighting a 600nm reflective red surface, it will be perceived as nearly black instead of the orange-ish tone under day-light.

If a given "white" light fails to reproduce the same perceivable colours, then it is not truly white for lighting purposes beyond locating things. "Narrow-band" white is suitable for convenience and security but not for decoration where it can completely skew the colour scheme.

Re:no, it is NOT a contradiciton

[Anonymous Coward]

Just to clarify, just because light looks to be a certain color to the (normal) human eye, does not mean is is composed of that frequency light. For example, a mixture of red and green light may look the same as yellow light, but it is not the same as pure yellow light, as revealed by a spectrogram. One could produce an infinite number of different spectra that looked identitically white to a particular individual.

Re:no, it is NOT a contradiciton

[utnow]

And if you check with any interior decorator, current florecent bulbs do exactly that. Yet we still use them... they attract fewer bugs for the same reason that the guy (parent or gp... not sure) stated... and most people will tell you that floro bulbs produce a cleaner looking white light than an incandescent. I'm not arguing with you... the color is crap. But it's a light that appears to be white, despite not falling under a perfect scientific definition of 'white light'.

Re:no, it is NOT a contradiciton

[GodGell]

that's what "white LEDs" do. as obviously a LED can only emit a single wavelength of light, white LEDs are impossible to create. but since there was a lot of demand for them, manufacturers started selling packages of 3 leds (a red, a green and a blue one) under the same package. that's what they use as white LEDs now. they obviously use more power and are brighter than other LEDs, simply because they are 3 LEDs combined.
and as an interesting thing, my sister says she sees the light coming from these as greenish white while i see them as bluish white. her eyes are green, mine are blue. coincidence?

Re:no, it is NOT a contradiciton

[Reziac]

The sodium street lights in Long Beach CA are brilliant yellow.

My truck is a pale jade-green (officially known as "Ford Puke Green, 1978 version").

My truck is *invisible* under Long Beach's sodium lights. From the driver's seat, it looks like the hood isn't there, you just see this blank area in front of the truck. And I once lost it in an empty parking lot, and almost walked into it before I found it.

Mind you, I have freakishly good colour vision, and can distinguish shades far more acutely than most folk. So it ain't just me. :)

And yes, if you walk into a Ford dealer and ask for "puke green" paint, they know which colour you mean :)

Re:no, it is NOT a contradiciton

[InvalidError]

Human vision is skewed.

The reason why fluourescent lighting and CCFL look whiter than white is the same reason that adding blue when washing white clothes makes them look whiter. Human sight is least sensitive to blue so boosting the blueishness of whites make them appear whiter.

Cool-white and RGB are fine for general lighting but not where colour accuracy is desirable/necessary.

Re:no, it is NOT a contradiciton

[Psion]

White LEDs actually use a blue or UV emitter coupled with a phosphorescent coating similar to that used in fluorescent lamps. There are RGB LEDs available, but they are marketed for their tunability, not their ability to produce white light.

Re:no, it is NOT a contradiciton

[GodGell]

well, there are the RGB LEDs that have 4 leads (a base lead and one lead for each LED), which indeed are great for multi-color applications, but as far as i know, LEDs marketed as white LEDs are simply RGB LEDs with both red, green and blue on the same lead.
guess i was wrong then :)

led's, worse than flourescents.

[plasmacutter]

I have an led flashlight.

led's emit a very cold light. Fourescent light is described as cold and "vitamin burning", but led light is even worse in this respect.

It works for headlights, emergency beacons, and select areas, but generalized room lighting is not one of those areas.

Re:led's, worse than flourescents.

[falconwolf]

led's emit a very cold light. Fourescent light is described as cold and "vitamin burning", but led light is even worse in this respect.

It works for headlights, emergency beacons, and select areas, but generalized room lighting is not one of those areas.

CFLs work fine for me, that's all I use. When I replace a bulb I replace it with a CFL. And while the ones I have don't have the "cold blue" tint, I prefer that over incandescent lights.

Falcon

As a lighting design student...

[maino82]

I can definitely see the benefits of LEDs when compared to other forms of electric light. They do produce more lumens per watt than most other sources, but they do produce a good deal of heat when combined together into a large array, despite what people may tell you. They also have the added benefit of efficiently producing (since they only produce light in a certain wavelength) just about any color you would want through color mixing of different color LEDs (check out the tunnel in the Detroit airport if you'd like to see a well done example). Personally, though, I would love to see more daylight in spaces rather than a push for the latest and greatest in electric light. If done properly, daylighting can greatly increase light levels in the workplace and lower energy consumed by electric light. Generally, this will lead to an increase in cooling load, but this is almost always smaller than the amount of energy saved by eliminating electric lighting (again, if done properly). So while I'm all for more efficient electric lighting, it would be nice to see no electric lighting used during daylight hours when the sun is readily available.

Re:As a lighting design student...

[FFFish]

So while I'm all for more efficient electric lighting, it would be nice to see no electric lighting used during daylight hours when the sun is readily available.

Or, if you can't avoid using the lights, power them by solar panel.

Re:As a lighting design student...

[Lehk228]

LED is less efficient than Flourescent or CF, LED lamps are somewhat more efficient than regular incandescent bulbs but really are better suited to flashlights due to their better perfomance at low voltages and harsh environments due to durability and long life

Source of Light...

[loyukfai]

The main light source of the future will almost surely not be a bulb. It might be a table, a wall, or even a fork.

I suppose it means the new dots can be applied to many things but they still need another light or electricity source? Anyway, I'm not sure about others but I'm not yet ready to have everything in my home shines. : )

thank you..

[way2trivial]

that was an excellent pic of the distribution.

so these would still attract insects, but provide a fuller light experience for humans as well, than fluro..

they already do this with blue LED's!

[Doppler00]

That's how white LED's work if I'm not mistaken. Although instead of quantum dots, they use phosphor or some other material. Are quantum dots more efficient? Try this: Take a blue LED and shine it into a white LED that is turned off. You should see a slight white glow from the white LED, even though the originating light source is blue! Kind of a neat and simple experiment.

Perty white light...

[Gothmolly]

The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.

I bet Marie and Pierre Curie thought something similar at one point. "Hey look, this lump of weird metal that we produced is glowing so pretty... hey, if I put it in my mouth, my eyes glow too! Fun!"

White LEDs are not that efficient

[Bishop]

The very best white LEDs are only as efficient as CFLs under ideal conditions. LEDs are best used for low light levels. When used for higher light levels the LEDs overheat producing less light per watt. CFLs are still the best for household lighting.

From TFA

[Beautyon]

"One big question remains: When a brilliant idea pops into your mind in the future, what will appear over your head?"

A Dollar sign? ... or more likely since we are talking about the future, a €uro sign.

What happpens to all of our sockets?

[Anonymous Coward]

We have, what, 20 billion light bulb sockets in the world? Will they gather dust? Do they have a dim future?

What do you think!

[Anonymous Coward]

FTFA "One big question remains: When a brilliant idea pops into your mind in the future, what will appear over your head?"

A lawyer?

Still a way to go yet.

[crawdad62]

I'm a professional firefighter and a lot of the guys have started using LED flashlights. I had just purchased my own (out of my pocket and not the city's) rechargeable StreamLight that uses a halogen bulb. When I started seeing the LED's showing up I thought I had made a mistake. They "seem" bright but after seeing them more and more I'm convinced it's just because the light is so white (slightly blueish) and clean.

However even though it looks brighter in fact it's less so and seems to accentuate shadows MUCH more.

I really haven't discussed power consumption with anyone yet but for now........ at least in this application....... I'll stick with the older technology.

Re:Still a way to go yet.

[johnny cashed]

The StreamLight you're using is probably considerably brighter. It also probably uses a lot more current, but I'm guessing you've got a rechargable version. I am not a firefighter, but I would say that one distinct advantage of LEDs is their shock resistance and long life. If I was involved in situations that I absolutely needed a flashlight to work (caving comes to mind) I would at least have a backup LED light. If for nothing else, to provide enough light to change the bulb in my primary light. Having used a Surefire digital 2 ultra, which has a 5w luxeon LED, I am impressed by the current high end flashlights. But it is a very expensive flashlight at $250. I would still expect that a high end rechargeable halogen light to better it in terms of brightness, but not by much. A 5 watt luxeon should better a 5 watt halogen bulb, but pobably not a 7.5 watt, and definately not a 10 watt. But if you drop your 10 watt halogen bulbed flashlight and the filament breaks, depending on the situation, it might ruin your whole day. It is still a trade off in terms of brightness vs. reliablity.

Re:Still a way to go yet.

[Zobeid]

If you study LED flashlights a bit, you'll find their strengths are long battery life and the quality of the beam -- not brightness. They produce a smoother and whiter-looking spot, and they don't become dim and yellowish as the batteries run down. But the sad fact is, one of the reasons the battery life is so good is because they simply don't put out as much light as incandescent.

If you want a good compromise, try to find a flashlight with green LEDs! They are more efficient, they're typically a lot brighter than white-LED lights. The only disadvantages are that you can't identify colors too well with it, and you can't get a tightly focused beam from a multiple-LED light. My favorite flashlight has 10 green LEDs. (I don't know what brand it is, it has NO markings, but it's the one from the Herrington catalog.) It puts out more light than any other LED light I've ever seen, but it's still no match for a halogen or krypton bulb with fresh batteries.

At the opposite extreme from LEDs are the Surefire lights. For sheer brightness, nothing else I've seen matches them, they're like palm-sized car headlights. The catch there is, you have to feed them expensive lithium batteries and you get only 15 minutes of light from a set!

LED disadvantages

[Temeraire]

Anyone who tries (like me) to build small lighting devices with LEDs rapidly discovers lots of practical difficulties. To equal the light output of one cheapo fluorescent tube you need hundreds of the little blighters. It is not easy to make their output look even, rather than dotty. And with that large number, reliability is a real problem. Even a 1% failure rate (amplified to 3% or 5% by the LEDs often being in series) rapidly translates into major unevenness. Even production lines struggle to make large arrays of LEDs stay 100% alight, but little people often get sold the bin ends, which fail rapidly in service.
      Also LEDs are NOT yet more efficient than fluorescents. Their data sheets never give the one number that really matters: what percentage of input energy actually emerges as light? The answer is usually frighteningly low. Therefore LED devices tend to cook themselves to death if run really bright.
      To run LEDs stably requires either a wasteful series resistor or an expensive semiconductor constant-current device. And cheap low-voltage power supplies are actually badly life-limited by their electrolytic capacitors. In my experience many LEDs die prematurely because of a failing power supply and hot sunshine.
      Don't get me wrong. LEDs are the future, but you must be wary of calling them energy-saving, long-lasting, or easy to use!

super bright white light....

[lightningrod220]

The front of my Mac has a white light, which I assume is an LED, that creates a "pulse" effect when the computer is on standby. That thing is so bright, I had to cover it up to keep it from being so bright that it would keep me awake... and it was less than a millimeter in diameter! Is that an LED? If it is, I would agree on the idea of using it as a light source.

Re:super bright white light....

[Wingsy]

Rod - I had the same thing with an iMac in my bedroom, until I saw a firmware update from Apple that dims the thing at night. I d/l it and now it's down to a reasonable level at night. It's cool.

Re:super bright white light....

[schnipschnap]

... and it was less than a millimeter in diameter! Is that an LED? If it is, I would agree on the idea of using it as a light source.

Nah, it's a lightningrod! (Sorry, but it was just so tempting)

Re:super bright white light....

[tpjunkie]

Actually, that could be due to the fact that if it is an LED, it would have a large amount of blue light in the spectrum. Blue light is actually responsible for regulating circadian cycles, which could have an effect on your sleep. In fact, if you shine a blue light on the back of a sleeping persons knees, it can screw up their circadian cycle, and they'll wake up pissed off and un-rested.

Re:super bright white light....

[Anonymous Coward]

In fact, if you shine a blue light on the back of a sleeping persons knees,

You have way too much time on your hands.

Only two problems...

[JediTrainer]

I've replaced most of the bulbs in our house with CFLs and generally my wife and I love them. There are just two issues which are pretty darn annoying at times (basides their appearance, which isn't a problem given that I've put them in lamps that have shades or other covers).

The first is that the bulbs still have a warm-up time. Sure, they light right away, but it can take several minutes before they're at maximum brightness. This can be annoying, say, in a kitchen or other work area where I need all the light I can get so I can see what I'm doing.

The second annoyance is that I can't use them outdoors. Once the temperature reaches below 5 degrees C or so, they won't light up at all. So I'm still stuck using incandescents for my patio lights. They're iffy in the garage too (not as bright).

But I will agree that they save lots of money, particularly in the summer when you're running the air conditioner. Who needs more heat in the house when you're spending so much energy removing it?

Re:Only two problems...

[tylernt]

"The first is that the bulbs still have a warm-up time"

In my experience this is entirely dependant on brand and model. I have some (GE I think) that have a totally dark delay of about 1 second, then they turn on nearly full brightness (which annoys the crap outta me). I have some older ones that come right on and take 10 seconds or so to come up to full brightness. And I have a few that slam on instantly to almost full brightness.

The fade-on effect can be reduced by using overrated bulbs. I.e., when replacing a 60w incandescent, install a CF that's a 75w equivalent. Works for me, anyway.

"The second annoyance is that I can't use them outdoors"

I have some on my back patio that have fired right up in the dead of an Idaho winter. Again, I suspect cold-weather performance depends on the brand and model.

Where they don't work is in motion-sensing fixtures. The motion-sensing circuitry expects a fully resistive load, and the CFs just freak out the circuit causing flicker or total failure to light.

Re:Only two problems...

[K-Man]

There are actually standard designations for how a fluorescent light starts. The classic flicker-on is called a preheat fixture, since the filaments on each end of the bulb have to warm up like incandescents for a second or two before lighting with an inductive jolt. "Rapid start" are kept preheated with a small current (seems like a waste), and "instant start" ballasts use a high-voltage jolt to start the arc in a few milliseconds. Instant start usually means an electronic, i.e. better, non-buzzing, high frequency ballast.

If you look carefully at a CFL package, it will usually say "instant start" if it has that feature, or "Ikea" if it doesn't :-).

Re:Only two problems...

[Vanye1]

They also don't work on dimmer switches, in my experience. Or at least so far none of the ones I've had do.

Re:Only two problems...

[lancejjj]

it will usually say "instant start" if it has that feature, or "Ikea" if it doesn't :-).

I have three Ikea CFLs in my dining room ceiling fixture. They start within 1/4 second I'd say - they're no problem and they were very inexpensive. And they're quite small in size (I needed small ones to fit in the 1950s-vintage fixture.)

Ikea likely source their CFL bulbs from various manufacturers over time - so maybe I was lucky. Yep, just tried it now - instant start.

Re:Only two problems...

[JediTrainer]

...but I wasn't talking about flicker on or the one to two second delays (I bought the *good* bulbs).

I was talking about the fact that it can take up to 5 *minutes* for a bulb to be full brightness. This is across several brands. Fluorescents just never get fully bright (in terms of lumens) right away. If I could have full brightness in 30 seconds or less I'd be happy, but I just haven't seen it across the 4 or 5 brands I've tried (across all price ranges).

Ultimately I settled for the bulbs that were instant-on. So it's great that there's virtually no delay between be flicking the switch and them turning on. But there's still a *huge* time lag between when they turn on and when they are at their brightest. Doesn't seem to matter if it's a 60-watt-equivalent or 100-watt-equivant either (the latter being the ones we use in our laundry room). I have to turn the light on several minutes before we do the laundry so we can see things best.

Re:Only two problems...

[deathazre]

The motion-sensing circuitry expects a fully resistive load, and the CFs just freak out the circuit causing flicker or total failure to light.

fully resistive wouldn't be the right term to use, as even incandescent lights aren't. They're just a big coil of wire, and the inductance of the coil outweighs the capacitance between turns. Try running an incandescent bulb on 120VDC -- it'll be noticably brighter.

(and no, there's no efficiency increase involved, all you're doing is raising the resistive voltage component by eliminating the inductive voltage drop, and susceptance doesn't consume power.)

Re:Only two problems...

[Anonymous Coward]

and after the digging around I had to do to remember the term 'susceptance', right after posting, I realize that is NOT the right term to be using.

s/susceptance/impedance/

and now I hate slashdot for making me wait to fix up a mistake.

Re:Only two problems...

[falconwolf]

The second annoyance is that I can't use them outdoors. Once the temperature reaches below 5 degrees C or so, they won't light up at all. So I'm still stuck using incandescents for my patio lights.

If your CFLs can't handle 5 degrees C they must be bad as I've got some in the light fixtures outside I put in more than a year ago and it gets below -10 C here and I've never had a problem.

Faclon

Spectrum?

[Crouty]

What the article does not tell is the kind of spectrum these quantum dots produce. Chances are most people will not feel comfortable living or working with this kind of light. Any info on this yet?

Re:Spectrum?

[julesh]

See the more informative article here.

"LEDs don't emit heat"

[Tau Zero]

I wonder how many people are going to read this in the article and assume that LEDs are not just more efficient than other types of lamp, but 100% efficient?

(I hate scientifically-illiterate journalists.)

Re:"LEDs don't emit heat"

[Anonymous Coward]

I wonder how many people are going to read this in the article and assume that LEDs are not just more efficient than other types of lamp, but 100% efficient? Probably not very many.

Re:"LEDs don't emit heat"

[Thu25245]

If you understand enough about thermodynamics to know what "100% efficient" means, you understand enough to know that it is physically impossible.

Re:"LEDs don't emit heat"

[MickLinux]

Good point. Just to add my 2 bits, when I was experimenting around with my own circuits, I burned myself on an LED. It was a pretty bad burn, too. If you set up your LED right, it won't emit *much* heat. But it will emit heat.

Re:"LEDs don't emit heat"

[Anonymous Coward]

there about 45-55% effiency

Would I need a laser?

[ehiris]

I don't understand. Would I have to shine a laser on my new quantum dot light bulbs or could they get activated differently? Using a laser doesn't seem too practical.

Re:Would I need a laser?

[Anonymous Coward]

RTFA. It works when pumping the quantum dots with a blue LED.

Re:Would I need a laser?

[Dahan]

As the article notes, they coated an LED with the quantum dots and got white light out of it, so no, you don't need a laser. But even if a laser were required, I'm wondering why you think using one would be impractical. Lasers may have been exotic tech back in the '60s, but they're everywhere now--many consumer devices use lasers.

Re:Would I need a laser?

[antispam_ben]

I'm wondering why you think using one would be impractical. Lasers may have been exotic tech back in the '60s, but they're everywhere now--many consumer devices use lasers.

How time flies - remember about ten years ago, when handheld laser pointers were being sold at every convenience store for under $10? They're probably 99 cents each at the surplus sellers now.

Re:Would I need a laser?

[wilec]

That's funny, it was the part that enticed me the most. I like the idea that I could power up (enhance? control?)the quantum dot LEDS emissions wirelessly with a laser. Seems this might be most handy. wilec

High Efficiency Homes and Power Consumption

[Anonymous Coward]

Hey, just thought I'd add that this site: FutureCrisis Has some really great tips on saving energy, peak oil and DIY electricity generation such as solar and wind power.

Re:High Efficiency Homes and Power Consumption

[HeroreV]

That's quite a catchy title.

Compact Flourscents DO burn out, or fail...

[Anonymous Coward]

I've been slowly replacing the incandescents with CFL in the house, and I guess I'm about half-way done. The Flourescents do need to be replaced every once in a while. Some simply fail, sort of burning up the base and a bit of the tube. Others get dimmer and dimmer with time so they need to be replaced.

At least that's been my experience.

-- ac at home

has anyone found the journal article?

[Anonymous Coward]

There is no Oct 18 edition (as MSNBC mentions) of the Journal of the American Chemical Society and neither the Oct. 19 nor the Oct. 26 nor any other i have looked at has an article on laser excited photons by Michael Bowers.

hmmm....

Re:has anyone found the journal article?

[quadwrench]

yes, here is the link to the actual article. http://pubs.acs.org/cgi-bin/abstract.cgi/jacsat/as ap/abs/ja055470d.html Have a nice day.

Mixed reviews from me

[Just Some Guy]

I've switched a lot of my bulbs over to the CFs available at my local home store (Feit Electric; their websites down right now or I'd link it). The problems I have with them:

1. Most of them start nearly instantly, but dimly. They get brighter as they go, usually peaking after a minute or so.
2. At least half of them smell like magic smoke when you get close to them. One of them had me looking for an electrical fire inside my walls until I figured it out.

Once they're up and running, they're bright, nicely colored, and cool to the touch. But having to wait a full minute for the stairwell bulb to get bright is pretty suboptimal.

Are these "features" of all CF bulbs, or is the brand I've been buying really crummy?

Re:Mixed reviews from me

[jfisherwa]

Sounds like a crummy brand. I haven't experienced this, but maybe I haven't been looking for it. Perhaps if it's a light that you seldom use, using a bulb rated higher than your needs will give you the output you actually want during warmup time?

Re:Mixed reviews from me

[DrLex]

Fluorescent lamps are not really suitable for applications (think toilet room/stairwell lighting) where the light only needs to be on during a few minutes, and is turned on/off many times a day. Even with the better fluorescent bulbs that have their full output immediately, there's still the problem that they'll wear out much quicker when turned on and off many times. The rated lifetime is most often estimated on a typical usage pattern where the light is turned on and off only once or twice a day, and burns continuously during a few hours. For such applications, a simple incandescent bulb is perfect. You won't save much anyway by replacing it with something more energy-efficient, if the bulb only burns a few minutes a day. You might even end up spending more money because you have to replace these more expensive bulbs faster than expected.

Re:Mixed reviews from me

[Yaztromo]

Are these "features" of all CF bulbs, or is the brand I've been buying really crummy?

I've recently converted my apartment to CF bulbs as well, and I've noticed mixed results in this regard. The Noma 60W equivalent bulbs in my hall and bedroom lighting fixtures don't exhibit this problem -- or if they do, the brightness differential is so minimal that I don't notice. They come on immediately and are at full brightness immediately (or at least as fast as I can perceive).

I also have a dimmable 100W equivalent CF bulb in the fixture in my dining room. It's a large General Electric bulb (and by far the most expensive light bulb I've ever purchased...), and it does exhibit this problem. It takes several minutes to warm up to full brilliance. However, a (non-dimmable) 100W equivalent bulb in my bedroom lamp from Noma is at perceptably full brilliance immediately upon switching it on.

Finally, I have four vanity globe bulbs in my bathroom. They are 40W equivalent bulbs from a company called "Globe", and upon turning them on they exhibit flicker and an obvious warm-up time. However, their warm-up is fairly rapid -- they seem to come on at about 50% brilliance, but within a second or so are up to 90% or so (going purely by perception -- I don't have the equipment to actually measure this). Within the next few minutes they'll be up to 100%.

There are a number of other lights here which have been converted to CF, but the above covers all the bulb manufacturers and types I have installed here. I've learned to deal with the warm-up issue in the fixtures where it's noticeable, and can live with these minor issues.

If you have such bulbs in places where safety is a concern however, you might want to consider switching brands.

Yaz.

Re:Mixed reviews from me

[Anonymous Coward]

My experience is that if you put multiple CFLs on the same switch the startup takes longer. For key areas (hall and bathroom) I use a mix of CFL and inc That way I get enough light to move around instantly with the full brightness a few seconds later. For me the lag was unacceptable until I did this, now I don't notice at all.

Re:Mixed reviews from me

[hattig]

1) is great when you get up at night and are fumbling for the bathroom ... I hate being blinded by standard lightbulbs. The slow-warm up ones are far nicer on the eyes.

2) I've never noticed any smell from these lightbulbs and my parents got into them 15 years ago so I've been around them for a long long time.

Re:Mixed reviews from me

[Megane]

Yes, you've been getting crummy bulbs. I've been replacing incandescents with helical CF as they burn out, with whatever was cheap at Home Despot, and I've never had slow start problems. I have had one (of three in a fixture) which buzzed a lot in the kitchen, so I swapped the noisy one out to the garage. I may also have had one die young.

The best part isn't the energy savings, it's not having to replace bulbs all the time. The savings in labor of replacing burnt-out incandescents may be even more than the savings on the electric bill, if your free time is worth anything.

Re:We'll need a replacement for the Goodyear Blimp

[scotch]

Note to mods: pointing out your own puns is grounds for down-modding.

My only concern...

[Aenema]

about these lights is what'll happen if I hook it up to a car battery.

Lightbulb socket

[hey]

I recall when phone jacks switched from those big honkers to RJ-45's. Seems that soon we'll have to switch to a more compact standard for lightbumbs. Otherwise the connector will dominate the size of the LED "bulb".

Re:Lightbulb socket

[dodongo]

Actually, IIRC, phones use RJ-11 connectors; the CAT5-type ethernet jacks are the 8-wire RJ-45s.

Re:Lightbulb socket

[Big_Breaker]

Handsets are RJ-11. The wall socket for a phone is RJ-22.

Theatres

[cdcarter]

What about in theatres? LED lights are becoming more and more popular now because of their color accuracy, but they take up alot of extra DMX addresses, and if you wanted to replace conventional fixtures, you would need all new dimmers. Most current SCR dimmers are built for only incandescent loads.

More information

[laing]

From a different article:

"A second significant difference, according to Rosenthal, is that it should be considerably easier to use the magic-sized quantum dots to make an "electroluminescent device" - a light source powered directly by electricity - because they can be used with a wider selection of binding compounds without affecting their emissions characteristics. Other research groups have reported stimulating quantum dots to produce light by applying an electrical current. Of course, those produced colored light. So, one of the projects at the top of Rosenthal's list is to duplicate that feat with magic-sized nanocrystals to see if they will produce white light when electrically stimulated."

The PMSNBC article doesn't get into much detail. There's a better source here.

Wow, big surprise....

[Anonymous Coward]

And in other news.... Combustion engine thought to eventually find a replacement.

Light bulbs are stone age tech

[Twinbee]

The sooner this (or another) technology comes along the better. Standard incandescent bulbs have a terrible colour balance (48% red, 33% green, and only 19% blue!). This distorts surroundings away from their natural hue.

What keeps people away from 'white' flourescents is how they buzz, flicker, and also spike in the green range (giving a sickly green hue to many surfaces).

Re:Light bulbs are stone age tech

[sirwired]

What keeps people away from 'white' flourescents is how they buzz, flicker, and also spike in the green range (giving a sickly green hue to many surfaces).

You should try a modern quality compact flouresecent. (i.e. NOT your $1.50 Wal-Mart special) I have put CFLs in every fixture in the house where it makes sense (not in fixtures where the bulb is visible), and they are great. The problems of a few years ago of requiring "warm-up" time, the flickering, the buzz, and the greenish cast have all been fixed. While the green tint is probably still there, it has been mitigated to the point that your eye will adjust automatically.

SirWired

Re:Light bulbs are stone age tech

[cnettel]

Just one "problem", the temperature of the sun surface is below 6504 K, while above 3300. Or, to be precise, you can't get a black body with a really even distribution, so there is no specific reason to look for 33/33/33.

the first and last vacuum tube...

[johnrpenner]

crts were the 'second-last tube' -- commonly being replaced now with LCDs.

the light bulb is 'the last tube' -- soon to be replaced by LEDs... :-P

j.

Re:the first and last vacuum tube...

[Cmdr TECO]

You forgot the one in the kitchen.

Re:the first and last vacuum tube...

[csplinter]

Don't forget microwave ovens, doesn't a magnetron contain a vacuum tube?

Re:the first and last vacuum tube...

[Athenais]

The backlighting in most LCD monitors is a mercury tube, though. :)

(LED backlighting is in the works, but such monitors currently cost several thousand dollars.)

Another fun link...

[alset_tech]

This article has an image of the new bulb.

Why it's still not time for White LEDs

[josephdrivein]

The main reasons why White LEDs are still not ready for general purpose lighting are:

Low CRI (Color Rendering Index) that means bad illumination compared to incandescent
Low temperature of operation (120-150C max)

Most electronic design that include hi power LEDs (such as LUXEON http://lumileds.com/) need to take in account hheat transfer.

Re:Why it's still not time for White LEDs

[julesh]

The main reasons why White LEDs are still not ready for general purpose lighting are:

Low CRI (Color Rendering Index) that means bad illumination compared to incandescent

And this discovery seems to solve that problem.

Low temperature of operation (120-150C max)

But probably not that one.

AC vs DC

[MDMurphy]

AC has it's advantages, especially for long distance transmission. But in a house, it's gradually losing out. If you don't count lightbulbs, I'd say I have more DC things plugged in than AC. So many of the outlets are connected to "bricks" or "wall warts" to change the high voltage AC to low voltage DC. Things that don't have an exterior brick, like the DVD player or TiVo just do the conversion internally. While the higher voltage AC might have some benefits of lower loss in the wires, I'd think that umpteen separate transformers and rectifiers are negating a large percentage of that benefit.

If lighting were go to DC, then a re-think of the home wiring would really be in order. If there were a "standard" DC voltage and current available to lower power devices, we might not have wall transformers with anything from 3v-12v hanging off our surge supressors.

So in-house DC makes lots of sense. Send the AC to things like ovens and clothes dryers, and DC to most everything else.

Re:AC vs DC

[Anonymous Coward]

Yes but the whole way the electricity is generated in the first place means it's an AC current.

Re:AC vs DC

[jimijon]

Yes I have been saying this for years. I think we should first patent the concept of a DC house and then create a smart wall jack that can determine what the DC requirements are. Of course we would need to start a standards group for a new IEEE USFirePower L33T specification for power cabling.

Re:AC vs DC

[shbazjinkens]

Yes I have been saying this for years. I think we should first patent the concept of a DC house and then create a smart wall jack that can determine what the DC requirements are.

I think Thomas Edison patented the idea of a DC house, didn't he?

What you guys are overlooking is that AC has very easy and efficient current/voltage transformation compared to DC, aside from power transmission benefits.

Re:AC vs DC

[lommer]

Ah but transformers are among the most efficient electrical components we know how to make - That wall wart is probably achieving between 3 and 7 nines of efficiency. Also, transforming already regulated AC is way more efficient than regulating DC.

Re:AC vs DC

[jimijon]

There are many obvious benefits to AC, however, when we get to the house and the vast number of electronic devices, DC rules. And, those darn transformers, bricks, etc., take up the most room and add to an expense. We need to create a new IEEE standard for auto-configurable DC power cords.

Re:AC vs DC

[LWATCDR]

You are are forgetting a lot of other devices that work better with AC. Anything with with an electric motor. Fans, vacuums, mixers, blenders, dishwasher. Also it is much efficient to shift voltage with AC than DC.

Re:AC vs DC

[Anne Thwacks]

Ah but transformers are among the most efficient electrical components we know how to make - Correct. But only economically at high power levels > 100Watts.

That wall wart is probably achieving between 3 and 7 nines of efficiency. Nope - it probably takes 30 watts and delivers 13 watts. unless its a switcher, in which case probably about 80% efficient.

transforming already regulated AC is way more efficient than regulating DC. True at high power levels, but not at low powers. I work for a manufacturer of high power AC regulators, and its not cheap stuff. At low powers, regulating AC is extremely inefficient. Its normally changed to DC, and the AC regenerated with an inverter.

In reality, things like phone chargers have switch mode power supplies. These can be >90% efficient (if cost is no object), but prefer to have a DC supply. However, off-line switching is more expensive and complex than a switcher doing DC to DC conversion at a low voltage. From the point of view of energy efficiency there is a really good case for having a house-wide DC supply of 5V (good for phones PDAs etc) or 12V (interchangable with stuff designed for cars) or 40V (forthcoming standard for all vehicles), or 50V (Standard for telecoms). - which will it be? [I personally favour 40V, but I doubt many people will agree with me]

There is also the issue of safety. A low voltage supply intended to supply all your equipment would have to be capable of supplying very considerable current. The lower the voltage, the higher the current. A 12V 100A supply might be needed if you are to power audio equiment, computers, etc. Try shorting a car battery with a screwdriver to see how much damage this can do! (I saw someone very badly injured when his metal watch strap went across a 5V 50A supply.)

DC is far more dangerous than AC because the zeros in voltage between cycles allow your nervous system to regain control of your muscles and pull free from the contacts. I know from first hand experience - a DC shock is far more scary because the loss of control of your muscles is far more complete.

Re:AC vs DC

[toddestan]

I think the point would be to have one large, efficient AC to DC power supply in the basement or whatever, then run the DC current to all of the little things we have (battery chargers, answering machines, alarm clocks, computer speakers, telephones, wireless routers, etc.). It would probably be more efficient - the problem is getting the house wired up and then getting all the devices to conform to some kind of standard (unlikely).

Re:AC vs DC

[Anonymous Coward]

I have been thinking about this idea for a while, and I have sadly come to an unforunate stalling point. The main benefit to using higher voltage AC in the house is that it allows the currents in the walls to be much lower, there for requiring thinner gauge wires. Most house wiring is rated at 15 Amps (RMS) before the breakers will blow, and at 110 volts RMS that is a decent amount of power at around 1.6kW. However that same 15 amps at 12V DC is only 180W for the whole circuit, a single CPU will suck that up, not to mention everything else. So in order to implement this system we would need 1/4" wires running through our houses, to handle the current and that just isn't that feasible.

Re:AC vs DC

[falconwolf]

Yes but the whole way the electricity is generated in the first place means it's an AC current.

Not all electricity is ac generated. PVs generate dc. When they end up in people's garages or basements, fuel cells will be dc.

Faclon

Re:AC vs DC

[lafiel]

What on earth are you talking about? That this is interesting just tells everyone how little AC power is understood.

An extremely simplicistic reasoning behind using AC is because it allows for the transmission of three-phase power, as well using magnetic properties to allow for the increase of voltage and decrease of current. Transmission line losses are, at the very least, (I^2)(R). To reduce that using transformers (which by definition, require AC current in order to generate magnetic flux) allows not only less power loss, but physical gains (such as less conductive material). To think that 'seperate transformers and rectifiers are negating a large percentage of the benefit' is absolutely ridiculous, as you wouldn't even be able to create a power network that travels over any distance without the principles of AC current!

This doesn't even begin to state the obvious, that not all appliances use the same voltage. What are you going to do if your entire house is DC? Use a chopper rectifier so that you can turn it back to AC, pass it through a transformer, and then increase/lower the voltage before turning it back to DC? Do you realize how completely backwards that is?

Do a little reading before making blanket statements that the world's electrical engineering foundations are no longer relevant. I suggest you start with principles of magnetism and basic RLC circuitry.

Re:AC vs DC

[MDMurphy]

I do understand, and I can read. It would be idiotic to suggest that the world start distrubuting DC, so I mentioned that AC is appropriate for that. Nor did I suggest a house running entirely on DC. Feel free to read my post again.

To repeat, and I'll type slowly this time, a large number of devices in a house today run on low voltage DC. If you don't count the light bulbs then I'd venture a guess that most of the electrical devices in a house today are low voltage DC. Since the orginal article suggested LED lighting, which is generally low voltage DC, then the majority of devices in a house then would be low voltage DC.

Since traditional houses are currently wired for higher voltage AC, this means many, many small transformers and rectifiers at each item: PCs, VCRs, Clocks, radios, cell phone chargers.. Most of these use different voltages and have different current requirements. While a large house wired for DC might have greater losses in-house than AC, the inefficiency of dozens of transformers and rectifiers aren't terribly efficient. The comparison I made about lossed in the many transformers was when comparing them to a single, or fewer, DC sources in a house.
While the original LED discussion spun many posts about heat, every brick and wall-wart that's running hot is also generating heat that is not part of an efficient energy transfer. A standard low voltage, low current, DC distribution in a house could have greater efficiencies. Running a DC clothes drier on on wires 100ft long would not be an example of a low voltage, low current application. But a cell phone charger or clock radio, or any of dozens of LED lamps would be.

AC equipment in the US is expected to work on 120v 60hz. Because that's available, that's what's built. If 5, 12, or 40 VDC was what was available in any house, that's what these low power devices would connect to. If there's a common source and connector, hardware will pop up to use it. The hundreds of stupid things that plug into USB jacks are an example. They aren't communicating with the computers they connect to, but just taking advantage of a common low power DC source with a common connector.

As for a whole house transformer, another approach might be for a couple transformers, but not dozens. And similar to how a UPS works, it might not be a bad idea for some of these DC networks to be battery backed up. A DC source, the battery, and DC lighting would make for easier lighting in a power outage. Depending on the efficiency of the battery charging, it might even be worthwhile to charge the battery during off-peak times and run the lighting off of the battery during peak times.

Back to the orginal posting about LEDs. If you were to have all the ceiling fixtures in a house be LEDs, and you knew this before building the house, I'd suggest that running 120v AC to all those fixtures and building in transformers and rectifiers in each socket would not necessarily be the best approach.

Re:AC vs DC

[hattig]

I've been thinking that as well. Standard electrical outlets could have the current AC plug socket (for whatever country you are in) and a WORLDWIDE standard DC 12V (? or 5V?) socket.

This is entirely possible - mandate it now, all new house builds will start including it, all new electrical refittings will include it, products will start coming with the standard cable to accept DC straight up, with an AC/DC convertor for non-standard properties. Companies will come out with AC-4DC bricks which will allow non-standard properties to at least run multiple DC devices off of one wart.

Then we could replace all the AC-DC wallwarts with DC-DC wallwarts :p

Re:AC vs DC

[hattig]

I really like the idea of a house-wide battery-backed-up DC power circuit, one for lighting (replacing the current AC lighting circuit (5A @ 230V in the UK = 1150W)) and one for power outlets (40V @ 15A = 600W on the circuit, enough for all the various chargers and low-power devices, and it would encourage lower-power device creation).

Things like amplifiers and computers can still use the AC outlet for their power needs.

If there was a power cut, my (new compliant) cable modem, my (new compliant) router, and my laptop would still be operational! Thus life's needs are catered for, and safety is improved because house lighting will still works instead of having to light up a bunch of candles. Also all the lights that have an integral AC-DC convertor can be reduced in size and get cheaper to boot. I imagine they'll need a new fitting standard too.

Re:AC vs DC

[Reziac]

So now I'm wondering about supplemental DC wiring in a house, where it could power lighting and former wall-warts... would it be possible to put an adjustable rectifier at each DC outlet, so you could set it for the device in question? or is it possible to do autosensing? (I've been told that some laptop bricks do that, and only supply the required voltage for that model of laptop.)

Re:AC vs DC

[StikyPad]

If lighting were go to DC, then a re-think of the home wiring would really be in order.

Incandescent lights do not prefer AC over DC; in fact I believe they work more efficiently at an equivalent voltage (VDC vs VACrms) because the filament isn't being deprived of current every 500ms. I don't think flourescent bulbs have a preference either, but the ballasts would have to be redesigned. In fact, some people who use solar panels and batteries to augment their electricity choose to wire their homes for DC (in addition to AC) for specific applications. This skips the inefficiency of inverting the power to AC, then rectifying it back to DC.

It's not lighting that prevents in-home DC; it's the cost of redesigning and manufacturing the power supplies and voltage regulation system that would be required. The costs would be nontrivial, and the benefits marginal.

160 bulbs?

[coofercat]

Where do you live? Blackpool?

Re:160 bulbs?

[The Optimizer]

Naaah... The answer's simple: 1) It's a big house 2) I have a lot of multi-light fixtures in the house.

I've got a lot of ceiling fans (11), and most of them have 4 or 5 light bulbs in them, and there's several chandeliers (TCP makes some great Candelabera base CF bulbs for chandeliers) which adds another 30 bulbs. Change the bulbs in the garage, attics, outdoor enclosures, closets, and so on, and the total adds up.

Re:We'll need a replacement for the Goodyear Blimp

[Nom du Keyboard]

A LED Zeppelin, of course.

How about an Iron Butterfly?

I second that... CFs vary by brand

[The Optimizer]

Since I had so many bulbs to replace, I wound up getting CF bulbs from several different manufacturers, depending on size/type. Usually where I could find the best deal, and due ot the fact that despite a lot of searching, there is no place that had the bulbs I need.

I've got GE, MaxLite , Greenlite, TCP, and Feit brand CF bulbs among others, and I as commented, there are differences. Some snap on instantly at near-full brightness, others pause a second, others take up to 10 seconds. The color differs slightly by brand too, even for bulbs rated the same color temperature.

There also seem to be difference based on size of bulb: I have 4 chandeliers in which I installed TCP 9w Candelabra CF bulbs (40 watt replacements) which has a skinny nose-cone shape and they take up to 30 seconds to warm up. In my ceiling fans, I use 9w Greenlite x-bulbs (40 watt replacements), which have a fat round A-bulb shape, and there is more room inside for the spiral tubing. Those bulbs seem to snap on at 95% brightness without exception.

This is awesome!

[Dr. Spork]

The frequency distribution of this light is so much more natural than the other low-energy alternatives! I wonder if it could be made to match the frequency distribution of sunlight more closely by just rearranging the mixture of the sizes of the quantum dots. Anyway, this is excellent news. It's because of the spectrum distribution of fluorescent bulbs that I refuse to use them. It's not that I like wasting energy, but even without ugly light, winter is depressing enough in upstate New York!

Re:This is awesome!

[Impy the Impiuos Imp]

An LED is a quantum dot? The article seems confused. Or am I?

Re:This is awesome!

[masklinn]

Quantum dots will be packaged as LEDs for usage.

Fluorescent Quantum Dots.

[Anonymous Coward]

"When you shine a light on quantum dots or apply electricity to them, they react by producing their own light, normally a bright, vibrant color. But when Bowers shined a laser on his batch of dots, something unexpected happened. 'I was surprised when a white glow covered the table,' Bowers said. 'The quantum dots were supposed to emit blue light, but instead they were giving off a beautiful white glow.'""

And what if you replaced the phosphorus coating in a fluorescent bulb with quantum dots?

--

LED Efficiency

Re:Fluorescent Quantum Dots.

[eclectro]

And what if you replaced the phosphorus coating in a fluorescent bulb with quantum dots?

I do not think that you would want to. The tube lifetime would be the same as it still is a tube. So there would be no cost benifit

That's the whole idea with LEDs - they are solid state and last considerably longer.

Re:Fluorescent Quantum Dots.

[Anonymous Coward]

> And what if you replaced the phosphorus coating in a fluorescent bulb with quantum dots?

Exactly the thought that occurred to me - present flourescent tubelights have an efficiency of about ~100 Lumens/Watt, lifetimes of 20K hours, and cost less than $3 for a 3000 Lumen lamp.

http://www.rdl-inc.com/starcoat.htm

If you replace the phosphor coating with Cadmium Selenide quantum-dot coating, you get to keep all the advantages of flourescent, including the manufacturing infrastructure, efficiency, etc., but you get a color spectrum closer to natural sunlight (Of course, the coating will be more expensive to manufacture initially).

LED Efficiency

[Anonymous Coward]

I've seen studies showing how LEDs actually produce less efficient lumens total. They have a much narrower tunnel of light, and so actual lumen output is lower. In their lit spot, however, they output a fairly high level of lumens. Thus, often times lumen output is determined by different formulas.
I think they may have come out as less efficient than incandescents.

Anyone else hear of this? Has it been rebuked or anything?

Inventor at the local gun range?

[ChicagoArea]

Note to self: Do not take Michael to the gun range with me.

Material Insights

[Doc Ruby]

FT"It turns out that these were crystals of cadmium and selenium that contain either 33 or 34 pairs of atoms, which happens to be a "magic size" that the crystals form preferentially."

I wonder if the 33-dots shine differently than the 34-dots. If so, I wonder whether material of pure 33-dots (or 34) will have even more useful proprerties, like emitting perfectly predictable spectra. Currently, I believe we use only either lasers or relatively expensive pure-metal machinery for those applications. Such pure white light and reflective ceramics could have interesting architectural and informational applications, especially if they remain as cheap and efficient as the research material.

Halogen?

[NigelJohnstone]

Where's one for Halogen?

Re:Halogen?

[farquharsoncraig]

In a halogen light, the tungsten filament is not enclosed within a vacuum, but rather a capsule of a halogen gas which somehow allows the filament to burn hotter and longer. If replicating sunlight is the goal in artificial lighting, then this is an interesting question. Since the emmission spectrum of blackbody radiation is a function of temperature, then a halogen lamp would be perfect if it could radiate at a temperature of 6000 K, the temperature of the sun's photosphere.

Where the Blues Go

[Doc Ruby]

Even that more detailed (and clueful) article doesn't mention much about the "phase shifting" effect that transmutes blue frequencies to all the others in white light. It just says that blue-emitting dots originate light in their centers, while the white emitters originate the light in their surfaces. Why does that matter? How does cadmium selenide emit white? Perhaps the big crystals somehow absorb the longer wavelengths as the light travels through the crystals from the center. But I'd like to see actual theories, especially if they're qualified with experiment.

Re:Where the Blues Go

[binarybum]

Quantum dots are fluorescent in a unique way - they have a very wide excitation range in the blue/UV and very specific emission wavelengths with huge stokes shifts that depend on the radius of the excited dot (it's a quantum cavitation effect that I'm not even going to try to go into here). As for getting white light - my best guess is that he actually prepared a very sloppy batch of dots and the white light comes from many different sized dots and thus many different wavelengths being emitted at once.

Re:Where the Blues Go

[Doc Ruby]

I dunno, the article says his dots are 33 or 34 atomic pairs each - the very reason for the effects. That's a pretty specific size, not at all "sloppy".

Re:Where the Blues Go

[binarybum]

Yep, I was wrong. The full text peer reviewed article is availabe: J. Am. Chem. Soc., ASAP Article 10.1021/ja055470d S0002-7863(05)05470-3
Web Release Date: October 18, 2005

  Basically though: Magic-sized nanocrystals are so small that the electron wave function has significant overlap with the selenium surface sites.17,18 Therefore, any hole trapped on the surface would likely encounter the electron before nonradiatively relaxing to the ground state.

        Quantum yield is currently only at 2-3% - I'd be curious to know what the theortical max for the quantum yield would be assuming better manufacturing of the dots. Also, these things do not last forever - in the paper they take them out to ten days of excitation, but I imagine it might be quite a challenge to extend the life of these.

Re:Where the Blues Go

[Doc Ruby]

I'd like to see the actual spectrum of this "beautiful" white light. And see how its spectral lines are produced by the gaps in the cadmium and selenium.

Also, why shouldn't the dots last "forever"? Just bouncing their electrons up and down seems metastable. Unless the statistical average allows some electron dynamics to drive some dots' molecules apart, recombining with other atoms which behave differently. In which case, we might see vacuum chambers with scavenger atoms, somewhere between the "pure material" approach in this lab, and Edison's lightbulb. So the dots just reform. Or perhaps they'll degenerate to noncrystalline forms that behave differently. What makes you say that they'll wear out?

Re:Where the Blues Go

[binarybum]

Well, I wonder why they only went 10days with their experiment. your typical incandescent gives 1000 hours and a halogen gives even more. Maybe they were just in a hurry to get it published. I have definitely seen quantum dots bleach - not sure if the effect is thermal or if the fluorescence process is itself degrative. All the hype says they are unbleachable, they are certainly more robust than conventional fluors, but they do bleach and even blink. Afraid I could not find the mechanism, but here is documentation of someone else observing this:
Journal of Microscopy
Volume 202 Issue 1 Page 2 - April 2001
doi:10.1046/j.1365-2818.2001.00829.x

perhaps stablizing them in something like polyurethane and maybe keeping them cool is enough protection to prevent this from being a significant problem - but I'd like to see that this new lightbulb could at least last as long as current incandescendts before I get swept away in the hype.

Incandescent's days may be numbered

[travail_jgd]

I'm an LED flashlight geek, so I'm realistic when it comes to lighting a house with LEDs. I'd be surprised if in 20 years we weren't replacing CFLs with LED bulbs, but at the moment it's not a worthwhile investment.

Right now, I'm happy with my CFLs: for the wattage needed to light my living room and foyer with incandescents (140 watts), I can light my whole apartment on a dark October day. It's definitely a mood-lifter to not have to worry about my electric bill, or have the place look like a funeral home.

OTOH, incandescents may not be so quick to fade away: the efficiency of tungsten filaments can be significantly increased by using crystals instead of wires.

Additional step-down transformers for your house?

[Spy der Mann]

Like Fluorescent, requires supporting circuitry -- doesn't plug directly into AC wiring.

Just like most modern electronic devices...

I have a printer, an electronic keyboard, a hub, my MODEM, the Playstation, the cellphone battery charger... each one requires ONE power supply.

Man, you'd have to see my computer setup!

THREE multicontacts in series. One for the monitor and the UPS. The second goes into the UPS, and that's where my PC is plugged in. The third one goes into the second one, and that's where the bulky transformer power supplies go.

(I'm sure Edison didn't think about that one!)
Clearly this has to change.

I'm wondering if in the future installations will provide an additional stepdown transformer, say, from 120 to 12V AC so you can plug your electronic devices in it.

This of course, would include the LED lighting and your e-paper 48" TV's.

Obligatory

[Anonymous Coward]

I for one welcome our new light-emitting overlords.

White glow...

[HermanAB]

Hmmm, if you shine a strong enough laser on *anything*, it can give off a beautiful white glow...

Not vacuum tubes

[Anonymous Coward]

Modern light bulbs aren't vacuum tubes. They contain an inert gas. This slows the evaporation of the filament, and allows the use of thinner glass.

Dimmable CFLs

[raygundan]

You have to find CFLs made for dimmers. I had ceiling lights in one of my previous apartments that had 4 or 5 recessed cans in the ceiling that took R40 bulbs and was connected to a dimmer. A google search turned up exact replacements, and this was back in 2000. The *only* niche-bulb I can't find is a G30 dimmable (globe bulb, like in bathroom light bars). I've found plenty of G30 CFLs, and plenty of dimmable ones, but none that are both.

Here's a quick link to a few-- these aren't the same ones I used, which came from some manufacturer I'd never heard of, but nonetheless, they're out there if you look for them.

Is this new?

[whyne]

http://www.llnl.gov/str/Lee.html

"With all these different colors, it's now possible to make light-emitting diodes (LEDs) from quantum dots," says Lee. "We've come up with a process so easy you can almost do it in your garage. We can put these dots in a polymer and make thin films that are 1,000- to 2,000-angstroms thick. This means we can create precisely tuned blue or green LEDs."

LEDs vs Dots

[maxwells_deamon]

I think what they are trying to say is that the new light bulb will be something like this:

Single freqeuncy LED light (high effiency but ugly/annoying color) will be used to generate the initial light. This will hit a thin film of dots which will reradiate the light as white light that makes humans happy.

Saves costs as you only need one LED and multiple LEDs do not really match sunlight anyway.

Of course the article claims no heat is produced! :-)

duh, you did say it is rechargeable

[johnny cashed]

oops, missed it the first time.

But when

[Anonymous Coward]

will I finally be able to get my LED based HighDef big screen tv for less then 3k?
seriously, the lightbulb was a great invention, but it's too flipping fragile, and uses way too much power for today's world (especially as the developing world continues to develop, and we continue to generate electricty via fosil fuels)

Some things NEED incandescent bulbs.

[antispam_ben]

Okay, so it's not the most common application:
http://www.billsbest.com/thsidebender.html

But also, someone mentioned the Easy Bake oven. I suppose future versions will use a different heat source, perhaps a laptop computer.

Knock yourself out!

[Anonymous Coward]

As many light bulb jokes as your heart desire: http://www.ahajokes.com/light_bulb_jokes.html

Perhaps, but...

[msauve]

that only applies to the perception of the emitted light itself. However, objects illuminated by such a light source may appear to be significantly different in color than they would under a broad spectrum white light, since they may reflect light in narrow bands not matching those of the source.

Combining narrow spectrum RGB sources can work to produce whatever perceived color you want, as in a display. It does not work for all reflective lighting needs, so a solid state broad spectrum source still fills a need.

Recommend the Home Depot store brand

[gstovall]

I highly recommend the Home Depot store brand of CF bulbs. Like many other people, I went through a large variety of different brands of bulbs (Feit, Phillips, GE, several other brands) before standardizing on the Home Depot bulbs.

They are instant on, and the light from the 60W equiv bulbs is close to full brightness within just seconds. And at $10 for 6 13w (eqiv to 60W incandescent) mini-twist bulbs, the price meets my criteria.

For years now, every bulb in my house except for the decorative globe ones over a couple of vanities are CF. In fact, when I built my current house a couple of years ago, I packed up all the old CFs from my old residence (replaced them with incandescents) and am STILL using the bulbs in my new residence.

Warning about CFs. Some automated/remote control circuits for lighting systems don't like CFs very much. I found that CFs in my remote control Hunter ceiling fans would flicker badly, unless I left one of the bulbs as a low wattage incandescent. I'm guessing that the control circuit needs a certain minimum resistive load in order to latch properly. The same is true for some motion sensing light switches. One motion sensing light switch I have would allow the CFs to flicker in the OFF condition, unless I had a low-wattage incadescent bulb on the circuit, I guess to provide a drain load.

here ya go

[Quadraginta]

A laser.

What do I win?

Re:here ya go

[BKX]

Nothing, because your wrong. Lasers may not EMIT heat, but they sure as hell produce it. Ever use a laser pointer continuously for more than a few minutes?

Quantum dots and academia

[cejones]

Until a real LED company like Nichia, Cree, Lumileds or Osram comes out with a statement like this one concerning the light output of quantum dots, please take this article with a large grain of salt. Quantum dots and solid state lighting are great for academic research... but that is about it.

What's the difference really?

[tinkerton]

I always thought that the AHA-erlebnis had a missing H. Somewhere.

Re:We'll need a replacement for the Goodyear Blimp

[Anonymous Coward]

How long did you wait to unleash that one ?!?!

Fire in the stone age

[big.iron.wiz]

"Look, mother! I have invented the bright white light"

Like duh!

[solarcell]

What you seem to be missing is that the Sandia people were mixing three different colors of nanocrystals to get 'white' light. What the Vanderbilt folks did was using a SINGLE material. Thats the big deal. Early on, folks made nanocrystals using high temperature pyrolysis of dimethyl cadmium and selenium dissolved in a phosphine. There were two different emission features: the bandedge recombination and a large broad 'deep trap' feature. The deep trap feature was named for the nanocrystals precipitated from aqueous solutions which had lots of physical internal defects. The pyrolitic synthesis does not have any internal defects (well less than one per dot) Then came using cadmium oxide which was 'greener' and not pyrophoric like DMC. Read safer and easier to work with... Well part of the change from DMC to CdO was adding an amine into the solvent mix. When you add the amine the deep trap feature disappears. The deep trap feature is actually recombination of the excition (emission) where one of the charges was trapped to the surface. Since there are many different types of surface sites, you get a varity of states being emitted from. Well the Vandy folks made them SO small that the charges have no choice BUT to recombine on the surface and therefore take advantage of the multitude different energy surface states and therefore get 'white' light emission. Of course this is the most plausable guess. The paper doesn't prove anything. QToad

I don't kow if this is what you're loking for but.

[falconwolf]

Can you point me to documentation of LEDs being 3 times as efficient as fluorescent? What I have mostly seen is that they are about the same efficiency. With the LEDs being about 3 to 4 times the cost.

Warning it's a pdf, Here is a lighting test, which lighting technology can produce the most light for the least power? The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Falcon

Completeness of spectrum is another issue.

[falconwolf]

Cheap fluorescent tubes have huge mercury spikes and little red - maybe 55% on the accuracy scale. Good tubes achieve 95% - a marked difference. This is independent of the colour temperature.

Both incandescent and fluorescent lights can throw off the colour in photography without taking precautions. Incandescent light typically gives a photo a yellowish tint while fluorescent can give a blue or greenish tint. When I took photography in college some of the labs we were assigned we had to work with incandescent and fluorescent lights. Myself, I prefered the assignments we had for the outdoors, one of my favorite places to shoot photos around here is a lake, and at night. When it's warm a lot of sailboats and windsurfers will be on the water, when it's dry without snow quite a few people inline skate/Rollerblade on the paths around the lake. And when frozen people will be on the lake ice skating or windsurfing on boards will blades.

Falcon

Re:AC vs DC, yeah, but

[Anonymous Coward]

As some equipment, like power devices (laundry machines, refrigerators and the like) are more efficient on AC power, you will have to cater for 2 in-house transmission systems, a DC one and the regular AC one, doubling the labour and installation costs on this supposed DC house. Ppl havent even adopted solar pannels in their roofs because cost clouds their judgement on technical benefits.

Second, as you grant AC power is good for transmission, power to this DC house will be delivered to the neighbourhood via AC, and then it will NEED to be converted to DC wouldn it, replacing all the small converters for dedicated tasks, for a huge single one installed somewhere in your house, that is constantly (as ppl would go for the cheaper as in, innefficient, power hungry and electrical pollutant current waveforms) converting power to supply this energy, i dont really see the purpose of your proposal.

Case dismissed.

with no repetitive sales: unlikely

[chocotofferts]

at Philips they discovered (2 my knowledge, undoubtely someone else 2, anyway) the lightbulp that didn't need replacement. Lightbulp for life... forget it.. light makers need sales.. probably same here, no markup sales? forget it. same reason in france they stopped selling the metal filters that you could use for your filter coffee.. end result: everyone is buying filter packages

led vs cfs lights

[falconwolf]

I can pick up a compact fluoro for a few dollars and get 150W incandescent equivalent. No LED comes close to that.

Why would you need an LED light that big? LEDs put out 3 or 4 tymes the amout of light a fluorescent light does and fluorescent lights give out 3 or 4 tyme the light an incandescent light does. So a 15 watt LED should put out as much light as a 150 watt incandescent. Years ago I started replacing my incandescent lights with CFs, when one burned out I replaced it with a CF. But now I'm thinking I may start replacing my CFLs with LEDs. Because CFs last a lot longer, it'll take some years before I replaced all of them. As I don't plan on being here, continuing to live where I do now, I don't know if I will or not.

Faclon

Re:led vs cfs lights

[njh]

That is not true. LEDs make excellent task lighting and nightlight (I have little solar power garden lights that look good and make navigation easier). A 15W LED is currently impractical - I have tried Luxeons, arrays and that new korean brand and none are as good as a compact fluoro. (let alone as cheap!) The 150W equivalent compact fluoro I'm referring to is only 22W.

I also have LEDs mounted in the ceiling drilling through the plaster using red, powered by a trickle charged gel cel. This gives me night light in a power failure for only a few dollars outlay. LEDs are very reliable and don't need 240V inverter power to run (I actually made a simple constant current buck-boost driver for the led string though, which is beyond most people).

So you can see I've done the LED thing, and believe me, they aren't a good white light source yet.

LiveScience.com

[samkass]

The original article, which both MSNBC and Yahoo linked to when reposting it on their sites, was on LiveScience.com.

http://www.livescience.com/technology/051021_nano_ light.html

I have trouble liking fluorescent lights

[falconwolf]

I prefer fluorescent lights over incandescent lights myself, especially when they have a slight blueish tint. Then again sometymes I prefer candlelight and to me incandescent isn't like that at all, generally I find them too harsh whereas candlelight is soft. My fav light is sunlight but too much blinds me, I've got the darkest sunglasses I could find and on some days they simply aren't dark enough.

Faclon

Chuckle...

[David Rolfe]

This funny typo gave me a chuckle :-)

"You defiantly notice it" while you shake your fist at the lights, "Damn you eerie blue-white lighting, Damn you!"

LED vs fluorescent vs incandescent lights

[falconwolf]

From the article, LEDs produce twice as much light as a regular 60 watt bulb. I'm really not sure how to think about all of this. If LEDs produce twice as much light as a regular 60 watt bulb, how does that make LED lights better than compact fluorescent bulbs, which can produce four to five times as much light as an incandescent bulb of the same wattage?

Warning it's a pdf, Here is a lighting test, which lighting technology can produce the most light for the least power? The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Falcon

Re:LED vs fluorescent vs incandescent lights

[QuietLagoon]

The hands down winner is the light emitting diode (LED) which makes three times more light per watt than a compact fluorescent and 30 times more than a standard incandescent.

Then you have to wonder why a research article published under the website of Vanderbilt University says of LED lights that "they are capable of producing about twice as much light per watt as incandescent bulbs".

Don't you think that a Vanderbilt University laboratory would be able to discern a 30-to-1 difference, especially since a random website on the web sees that 30-to-1 difference?

I mean, it's on the internet, homepower.com must be correct, right? The pictures in that pdf file sure do look profession and scientific.

Right on, plus redundancy.

[David Rolfe]

I agree. LEDs are great in their niche. Diodes are much more shock and crush resistant than CF tubes or incandescent bulbs. For this reason, I'd have to say that for anything that is out of harms way (cieling light fixtures, maybe even table lamps) that CF is the way to go. Keep LEDs where shunts and bumps are real and the redundancy of arrays are a huge boon... in cars, flashlights, road flashers, traffic lights, etc. A single point of failure in a ceiling light isn't as big a deal as the failure of, I don't know, a brake light or muzzle/tactical light.

That's my two cents ...

fluorescent and LED lights

[falconwolf]

They do not cast nearly enough light. The light color is a disturbing and unnatural color, usually with too much blue in it.

I find the blue tint of fluorescent lights better than incandescent lights myself. If LEDs were to have the same tint as fluorescent then I'd probably prefer them too.

Florescent tubes are FAR superior to LED lights and yet so many people prefer good old incandescent lights to even florescent tubes.

All of my lights are CF lights. Starting years ago as my incandescent lights burned out I replaced them with CF lights. And now I may replace my CF lights with LED ones. I don't know of any places in my area that has them and I'm wary about ordering them online so it may be some tyme before I get any.

Hell, even something as simple as a flash light. Try an LED flash light and then try a xenon Mag Light and tell me which one rocks your socks.

I've got a Mag light from years ago with an incandescent bulb but somewhere I read an article with schematics on converting it to use an LED and thought I might do it.

Falcon

flicker of fluorescent bulbs?

[falconwolf]

There is something to be said for having a soft, warm light that doesn't flicker like Flourescent. I couldn't wait to get back my "energy offender" bulb!!!

All I use are CF, Compact Fluorescent, bulbs and I haven't had any problem with flicker for years. About the only tyme I see fluorescent lights flicker is in stores, and when they do it hurts my eyes. This, flicker, used to be a problem but that has been fixed.

Falcon

Re:flicker of fluorescent bulbs?

[Fishead]

Yeah, I agree, Flourescents are getting better. I do have a flourescent fixture above my fish tank for the plants, and that doesn't flicker. The plants are gorgeous too.

Engineer at work has 2 fixtures in his office that have a HORRIBLE flicker. I am not sure if he just doesn't notice, or leaves them like that so people don't linger too long in his office.

Re:flicker of fluorescent bulbs?

[falconwolf]

Engineer at work has 2 fixtures in his office that have a HORRIBLE flicker. I am not sure if he just doesn't notice, or leaves them like that so people don't linger too long in his office.

That could be, but me I'd use that as an excuse to get out of the office. Since it's been years since I've done it I don't know what my reaction would be but I don't think I'd last too long if I had to work in an office hour after work, day in and day out. To tell the truth I don't know if I could even work more than a few hours a day.

Falcon

Only two?

[Overzeetop]

Hmmmm...

I'd add: Shitty color rendition, misleading wattage equivalents, and poor compatibility with incandescent (read: affordable) dimmers.

I have yet to purchase a fluorescent which has fooled me into thinking it was an incandescent from a color rendition standpoint. Maybe I'm just sensitive, but I really, really like the glow of blackbody radiation. It feels comfortable, warm, and inviting.

Now, I have used fluorescents for specific tasks - kitchen "boost" lighting over a work surface and soffit lighting in a closet. Both were high CRI (93 or 95, if I remember correctly, at about 4000K) and did their job admirably. If I had to do it again, I'd probably go with the 5000K 98CRI lamps (aka daylight). Still, I wouldn't want them in my living room or bedroom.

I think the perceptable wattage difference is about 1/2 to 2/3 of what is advertised. I find that I need to almost double the "recommended" replacement value to get equivalent light.

Finally - dimmability. I like to have lots of light - hundreds of watts in a typical room - when I'm working, but I prefer much lower light for TV viewing or casual times. Take a bathroom, for instance - 200W is about right for getting ready in the morning, or during the day, but you could burn your retinas out in the middle of the night or when yo ufirst roll out of bed. A dimmer solves this - low light when you need it, high light when you can take it. In fact, I put dimmers in most of the my rooms, and CFLs just usually don't work. In fact, I've taken to carrying an incandescent around with me on travel so I can get a "real" light by my bed. Also, I wake up with a SunRizr (just google it) which simulates a sunrise with bedside lamp intensity - can't do that with a CFL. (If you have to get up before dawn, and would like a painless way to do so, go get one. Yes, they're stupid expensive - $130 give or take. Worth every penny, I swear!)

homepower.com must be correct

[falconwolf]

For all I know they might both be right. I don't know where Vanderbilt's, er the ones involved, were coming from but "Homepower" is focused on "home made power" where individuals, many living off the grid and producing all of their own power, are concerned with energy self sufficiency. They stress as much as they can on reducing electricity needed.

Falcon

Re: Astronomy

[saskboy]

I can tell you're not an astronomer. The white light pollution is the worst, at least with sodium lights you can use a filter and still do some spectography.

How about an Iron Butterfly?

[falconwolf]

In-A-Gadda-Da-Vida?.

Faclon

huh?

[Quadraginta]

Er, but the original request was for something that emitted light without emitting heat.

Re:huh?

[BKX]

I suppose.

Re:huh?

[lkeagle]

You guys seem to be mixing up your definitions a bit. Lasers, LEDs, and just about everything else in the known universe produce heat. Heat is simply the transfer of thermal energy. If the temperature goes up, then the molecules of the object have more energy.

In fact, incandescent light sources rely on this. They increase the temperature of a filiment to the point where the molecules bounce off eachother so hard they knock electrons into a higher energy level, when an electron falls back down to a stable level, it emits a photon.

It just so happens that we are particularly sensitive to infrared light in a specific way -- we interpret these frequencies as being 'hot'. This probably developed through evolution so that we don't do stupid things like touch the pretty fire. If this is your definition of emitting heat, then sure... only light sources that emit infrared light will be emitting heat. This applies to any light source.

But remember, UV will burn you a lot faster than IR, even though you can't really feel it until it's too late. By this definition, if the light can be absorbed by something, then the temperature of that object must go up. In other words, if it's emitting photons that will be absorbed, it's emitting heat. Since practically nothing is 100% reflective or translucent, this definition works.

Of course, all of these light sources 'produce' heat due to their inefficiencies. When the materials that make up the light source get hot enough, chances are they will start emitting infrared on their own. We will feel this as heat.

Note that this has nothing to do with physically touching the light source, which would be a heat transfer by conduction, not radiation.

Re:Kruitof's Curve

[Anonymous Coward]

The color temperature is related to the light levels. At low light levels our eyes see better with warmer color temperatures, such as candle light or incandescent lamps. At higher light levels we see better with cooler color temperatures that more closely match daylight. Kruitof's curve will show a graphical relationship between light levels and color temperature. At low light levels things will look strange when using a 6500K color light, but at high light levels it appears normal.

motion sensors for outdoor lights

[falconwolf]

Where they don't work is in motion-sensing fixtures. The motion-sensing circuitry expects a fully resistive load, and the CFs just freak out the circuit causing flicker or total failure to light.

Uhm, I didn't know this. I use CFLs outside but I wanted to replace the fixtures with motion sensing ones. Guess before I do I'll have to check on this.

Idaho winter

For me it's a Minneasota Winter and I haven't had any problems using CFLs outdoors.

Faclon

Re:motion sensors for outdoor lights

[tylernt]

"I use CFLs outside but I wanted to replace the fixtures with motion sensing ones"

Well, to be fair I am using a crappy Wal-Mart fixture. Perhaps a motion sensor that wasn't made in a Chinese sweatshop from mass-produced, lowest-bidder components will do better with CFs.

Re:motion sensors for outdoor lights

[falconwolf]

Well, to be fair I am using a crappy Wal-Mart fixture. Perhaps a motion sensor that wasn't made in a Chinese sweatshop from mass-produced, lowest-bidder components will do better with CFs.

Well most if not all of my CFLs I got from Walmart, er Sam's. Then again it's easier to slap together a fixture than make a bulb.

Falcon

In-house DC = PoE

[spage]

In-house DC power supply does make sense—anything to get rid of those buzzing crappy Chinese wall-warts—but you need a standard. Fat auto 12V adapter holes aren't going to succeed.

I think Power over Ethernet could be one way this takes off. I'm wiring a new house with Ethernet jacks in every room, and as more devices get smart I hope they'll support powering from this. From Wikipedia, "IEEE 802.3af provides 48 volts DC over two pairs of a four-pair cable at a maximum current of 350 mA for a maximum load power of 16.8 watts."

USB and FireWire also provide DC power and ThinkGeek has numerous USB-powered gizmos but I've not heard of any house wiring including USB.

LED Lights

[MadGravity]

All my lights are LED 12 vdc and draw about an amp, but I could run ac lights (Compact Fluorescent) if I wanted to. The LED's give me enough light to navigate around the house and for reading. I also use them outside on a timer. I don't have to turn off the LED lights when not needed because they use so darn little energy, but I do it by habit. My whole house is solar powered: My system consists of : 1) AIMS 1250-Watts dc to ac Power Inverter. 2) 4-Uni-Solar US 64, 64-Watts @ 16.5 vdc @3.88 amps. 3) 1-Arco 55 Watts @16 vdc @3.4 amps. (I had this one for 20 yrs) 4) 2-40 Watts @17 vdc @ about 2.3 amps (I bought these second hand) 5) For a controller, I have a ASC-12/16 Specialty Concepts 12 Volt 16 Amp and a Lyncom SR-7 7-Amp Charge Controllers (regulates the amps to the batteries so that they don't over charge) 6) 2-L16 6vdc deep cycle batteries. 7) 1-2500 watt Honda generator (for those real cloudy days and washing clothes) This powers: a small freezer, all my computers, printer, scanner, and other computer stuff. I replaced my old 19-inch tube type TV with a 17-inch LCD TV that is more energy efficient (I save about 100-watts or so). The idea (for me) is to become energy independent and LED lights help me to acheive this.. //bob

Just a minor detail but...

[Godwin O'Hitler]

Will the dimmer switch now have to be reinvented? How do you modulate the light from a LED?

Re:It's about damn time - We need a new Moderation

[Insipid Trunculance]

....Tag.

Considering that the average lightbulb creates more heat than light... Kind of like most slashdotters!

I tried to moderate your comment and had to give up in the End as i couldnt decide whether You were Funny or Insightful.We need a new "Funny Because True" Tag.

To turn off a street light

[randmairs]

shine a laser pen light into its daylight sensor. The sensor will look like a black dot; usually on the west side of the lights. On the "cobra head" lights, it's in a protrusion cap above the lamp base. A light pen strapped to a tripod with tape works best for long periods of darkness.

What I don't get...

[Anonymous Coward]

Is all this talk about LEDs, when the discovery involves quantum dots and has nothing to do with Light Emitting Diodes.

Efficient Lighting

[falconwolf]

Thanks for the link, I bookmarked the homepage to explore the site. I noticed one thing on the page where it says there's a problem with Fluorescent lights, "Use halogen lighting for outdoor applications where temperature causes problems with fluorescents." I lived in Florida and never had a problem using them outdoors and I currently live in Minneasota and haven't experienced problems here either. I've lived and used CFLs in both heat and cold without problems.

Faclon

Mag-lite conversion to LED

[Hungry Admin]

LEDs are about to take over as the standard lighting in automobile headlights and flashlights. Their ruggedness and efficiency is pretty darn good compared to the alternatives. These quantum dots are a very interesting way of getting white light from blue or UV.

I've done the 5 watt LED conversion to a 2-D Maglight (also required converting to lithium batteries) as well as a simpler 1 watt drop-in bulb and reflector replacement for the 2-AA minimag. I think I will do the minimag conversion to another light or two. It is the best bang for the buck, and runs on commonly available AA cells, which cost about 20 cents each at CostCo for good alkalines. It retains the variable focus of the mini-maglite, a major plus. It is brighter, whiter, and the batteries work about 4x as long as they do with the original incandescent bulb.

LED-Replacement has a lot of drop-in replacements for various flashlight bulbs.

If you prefer to spend your money on a purpose-built LED flashlight, check out Amondotech for good deals on lights and batteries.

At Candlepower Forums you can find people who obsess over flashlights more than you or I do.

Flashlight Reviews is a great review site for various flashlights, including good definitions of the difference between lumens (overall output) and throw (how far away you can light stuff up.)

I'm just a flashaholic, and don't make any money from these companies.

Better street lighting

[GreenSwirl]

I also dislike the yellowish light from low-pressure sodium lamps. As I approach an intersection on a street lined with them, I cannot see the traffic signal once it turns yellow: it disappears into the mass of other yellow lights.

These yellow lights also compromise safety, as they hinder you from seeing pedestrians in your periphery at night. The bright blue headlights that everyone complains about glare from are actually great for nighttime peripheral vision. See this article by my colleagues.

Energy is obviously a big concern for lights operated by municipalities, and you can't beat the efficacy of low-pressure sodium. But remember they use this energy off-peak, when it is cheaper. With its long lamp life, an LED solution can reduce maintenance costs enough to offset incremental energy costs, saving taxpayers money.

The other argument against white light streetlights is light pollution. This is better addressed by managing the light distribution, cutting off light that needlessly aims into the sky. Also, using a 3-LED combination to produce white light yields a white that can still be filtered. A graduate student here at the Rensselaer Lighting Research Center just designed an "umbrella" LED outdoor fixture that employs this thinking.

In theory, 3-LED streetlights could also be used for signaling purposes. For example, the city could turn all the streetlights red when there is no parking allowed. Since they don't have a 5-minute warm-up time like low-pressure sodium lamps, they could also flash on and off, in unison or in sequence, perhaps to warn about emergency vehicles or a dangerous chase in progress. You get the idea.

Not necessarily

[BLKMGK]

Yes, they used an LED in this test but that may not be how it ends up being used in a production sense. Apparently you only need apply energy in order to excite these things so it need not be light from an LED...

If the new process can be developed into commercial production, light won't come just from newfangled bulbs. Quantum dot mixtures could be painted on just about anything and electrically excited to produce a rainbow of colors, including white.

Cadmium?

[BLKMGK]

Okay, an ignorant question but it ought to be asked I think - the material we're talking abotu here is partialy made up of Cadmium? Isn't that a heavy metal and doesn't it preset waste dispoal issues? Certainly we could be saving some energy if we could build full spectrum LEDs with this process but are we really goign to be better off with Cadmium laced parts all over the place? One of the linked articles also points out that making "bulbs" could move from a pretty much mechanical process to one that's almost purely chemical in nature. FAB plants are chemical in nature too - and produce lots of toxins. Are we going to be producing still more sources of toxins if we move in this direction? I'm wondering if this is really likely to be such an improvement if we reduce our energy needs but increase our waste disposal and environmental hazards.

Anyone have some insight here?

Re:Cadmium?

[Doc Ruby]

Tungsten bulb filaments are "dirty", too, and in much larger quantities than in this nanotech. I don't know whether it's been replaced by less toxic materials in modern lightbulbs, but LEDs probably produce lots of toxins in their manufacture. Of course, Cd concentrations at the factory could be large. All I can add to your important question is the point that household accumulations of Cd are probably too tiny to matter, and the insight that the introduction of a new, cheap, ubiquitous tech with hidden disposal costs is exactly the time to build recycling systems and costs into the original systems.

Re:homepower.com must be biased

[QuietLagoon]

If you look at the measurements that HomePower did, you will see that they used LED spotlights, and compared them to a CFL without a reflector. They did not even try to use a CFL with a reflector. No wonder their results were so good in favor of the LED lights.

HomePower said the experiment was performed to compare lights suitable for task lighting, as opposed to room lighting; then they avoid using a CFL with a reflector that is suitable for task lighting. In other words, they lit up the entire room with the CFL, but concentrated the light output of the LED bulb only onto the measuring photocell.

Makes you wonder about the results of anything else in that magazine.....

Re:homepower.com must be biased

[falconwolf]

HomePower said the experiment was performed to compare lights suitable for task lighting, as opposed to room lighting; then they avoid using a CFL with a reflector that is suitable for task lighting. In other words, they lit up the entire room with the CFL, but concentrated the light output of the LED bulb only onto the measuring photocell.

Makes you wonder about the results of anything else in that magazine.....

Someone else pointed out to me that in the following issue of "Home Power" they printed a correction saying the test focused on task not area lighting so LEDs would be better because they concentrate light into a small spot. CFLs are still better for area lighting. Sorry about the confusion.

Falcon

Re:homepower.com must be biased

[QuietLagoon]

Thanks for the follow-up.

20 degree beam

[demon411]

Did anyone address the issue of the narrow beam that lcd produce? This article says that lighting a living room with LED is still inefficient because of it.

From the article:

"All of the light from our LEDs is concentrated in a 20 degree beam, while the incandescent and compact fluorescent lights were tested without fixtures...and most of the light they produced was never measured in the test, since it sensed only light falling on the sensor. It's OK to compare different lights by how brightly they illuminate a certain size area...but put a reflector behind the compact fluorescent and incandescent bulbs in the test rig and the data would change significantly. Therefore, while the LED lights in this test may illuminate a small area as brightly as other lights, they are NOT significantly more efficient."