Popular Mecahnics article on LED lighting

[Anonymous]

Personally, I think in 10 years halides will be a thing of the past...

Illuminating The Future

BY JIM WILSON Photos by Lumileds





LEDs like the Lumileds Luxeon Star, above, will change the look of lighting fixtures, and save energy.

Hang on to your burned-out light bulbs. Your grandchildren could pay their way through college by selling them as antiques. After more than a century, the light bulb is about to go the way of the whale-oil lamp. The contender is the light-emitting diode (LED), perhaps best known as the little bump on the top of the TV remote control.

Remotes emit light in the infrared range, at frequencies below those we can see. The newest member of the family, white-light LEDs, emit light at frequencies across the entire visible spectrum, which means they can illuminate our surroundings with a clarity that's comparable to nature's original incandescent--the sun.

"Just as vacuum tubes gave way to semiconductors, the revolution in lighting can in some ways be compared to the revolution in electronics that began 50 years ago and is only now reaching maturity," James M. Gee of Sandia National Laboratories in Albuquerque, N.M., told POPULAR MECHANICS during a recent visit. Gee, a senior scientist specializing in renewable energy and energy efficiency technologies, said the switch from light bulbs to LEDs is being driven by more than America's fondness for the latest technology. On the contrary, we simply do not like to be left in the dark. Banishing the dark gobbles up 20 percent of the electricity generated in the United States. Yet, almost all of this electricity creates heat rather than light. Producing the white light needed to show the natural gamut of colors requires heating the filament of a light bulb to metal-melting temperatures. As a result, a typical 100-watt light bulb radiates roughly 95 watts into its surroundings as waste heat. The Sandia team estimates that switching to LEDs could reduce the nation's electrical consumption by 10 percent.

A more significant advantage is convenience. The absence of a filament and its surrounding vacuum-containing bulb makes LEDs extremely durable. They also last a long time. Engineers at Lumileds, the San Jose, Calif., company that makes the world's brightest white-light LED, estimates that their Luxeon Star model, shown above, will shine for 100,000 hours.





Cold Light
There are several approaches to generating light with LEDs. All are based on the same underlying physics--a phenomenon called radiative recombination. When an electric charge is applied to certain semiconductors, the interaction between the electrons and the so-called electron holes releases photons, or packages of light. The nature of the semiconductor material used to make the diode determines the frequency of the photons, hence the color of its light.

Between 1962, when they were first demonstrated by General Electric, and about 1985, LEDs produced too little power to be useful for anything other than tiny red signaling lights on electronics. In 1993, researchers at several universities perfected a high-efficiency blue-light LED. By combining different colors and using colored coatings, LEDs now can produce colors as pleasing as the best incandescent bulbs.

Despite considerable progress in 2002, a serious hurdle remains. LEDs are expensive, and for years to come they will cost more than both incandescent and fluorescent lighting.

For applications like traffic lights, railroad signals and aircraft lighting--places where dealing with a burned-out bulb can pose a serious safety concern--cost is a minor consideration. Spurred on by the federal Next Generation Lighting Initiative, major lighting manufacturers, including General Electric, Philips and Osram, have formed consortia with semiconductor producers to mass-produce LEDs. By some estimates, white-light LEDs could capture a quarter of the existing incandescent and fluorescent lighting markets as early as 2012.

Beyond Lights
The energy savings of LEDs is only the start. In the course of looking into new ways to manufacture better LEDs, researchers at Sandia have stumbled onto a remarkable light-related phenomenon. When Sandia's Shawn Lin and Jim Fleming assembled the tungsten used in bulb filaments into a lattice structure, they found they could essentially transmute wasted heat into light.

What puzzled the researchers was that the structure produced more light than expected. How the tungsten lattice repartitions energy between heat and visible light remains unexplained. "It was not theoretically predicted," Fleming told PM. "Possible explanations may involve variations in the speed of light as it propagates through such a structure."

Just how far the LED revolution will go in transforming the way we illuminate the world is likewise a matter for conjecture. Sandia's Gee offered this prediction: "As in the microelectronics revolution, many of the possible applications for solid-state lighting will occur in ways that have not yet been envisioned."

 

[Anonymous]

Hmmmm. It may be a good idea to invest some money in GE. :wink:

Nice article Sharky. Thanks for sharing.

Louey

 

[Bleeding Blue]

I just bought four for my nano a couple of weeks ago. I am going to try and build the power supply and fire them up today. Wish me luck. I will keep you posted.

Mike

 

[brandon4291]

--

 

[brandon4291]

And I was lucky enough to see a spectral data chart on these Luxeon mini daylight bulbs as well...5500K continual output (same as many reef MH daylight bulbs). A friend of mine bought a very nice luxeon star setup and we tested the outputs of the blue leds under a LUX meter--as suggested the blue-emitting LED's were emitting exactly the same frequency as standard VHO actinics, though in a much more pinpoint output. Several wired in parallel will light the heck out of a reef, would only take a few to run a nice pico setup. Expensive though, and also available in 5w. Basically that means I'd rather look down the barrel of a laser pointer before I'd let someone shine one of those 5w babies in my face... We were playing with the 1watters and I am still suffering from retinal spots.

B

 

[Anonymous]

And I was lucky enough to see a spectral data chart on these Luxeon mini daylight bulbs as well...5500K continual output (same as many reef MH daylight bulbs). A friend of mine bought a very nice luxeon star setup and we tested the outputs of the blue leds under a LUX meter--as suggested the blue-emitting LED's were emitting exactly the same frequency as standard VHO actinics, though in a much more pinpoint output. Several wired in parallel will light the heck out of a reef, would only take a few to run a nice pico setup. Expensive though, and also available in 5w. Basically that means I'd rather look down the barrel of a laser pointer before I'd let someone shine one of those 5w babies in my face... We were playing with the 1watters and I am still suffering from retinal spots.

B

I DLed the brochure from Lumileds. It has spectral info in it. Might be a couple days before I have a chance to go over it though.

How spendy are they? I mean at this point would it be more expensive than a $1500 halide/vho setup? (for say a 75 gal tank)

 

[Robin Goodfellow]

hi.
LED and blue LED has be subject of discussion in past few years in RDO and RAMR. However, I still not very convinced about the true value of it in reef application. I am not an expert when it comes to optical physics, but the following is my argument. Please let me know if it is not sound when it come to a more monochromatic light source, like LED.

In lumiled.com, the number it said is 120 lumens for a 5W LED. A 5 piece cluster for surgical application is 600 lumens at 25W. Now compare the lumens per watt to MH. I only have low Kelvin 175W MH numbers handy, so let me use it instead of more efficient 400Watters. A 175W MH is around 14000 lumens per bulb. That is about 80 lumen per watt. The LED is 24 lumen per watt, which is really good when you compare to incandescent bulb (at 17 lumen per watt). In reef application, with higher color temperature, the lumens per watt may go down to 50 or so, but ASAIK, it still beats LED.

 

[brandon4291]

I agree Robin, for a 75 g you must use nothing less than the five watters ($40 per!!!) and you will need hundreds of them. In no way are they cost comparable to a MH setup, and not as efficient per dollar investment. But, for us tweaks who work with nanos/picos only these new LEDs lights are more preferable than a date with Raquel Welch (circa '68 of course). I consider them more efficient than the current technique of stacking multiple PC's into a custom hood for the same system. Im talking solely about the Luxeons, not the average RadioSlack LED which I once thought was the top dog. Pcs are more efficient than those in spite of the heat; collective par output from a decent array of .3-.5w LEDS will not compare to a standard 13w pc bulb. However, for $350 bucks I could build a Luxeon display that will not require fanning and still get me the exact same measures as the original PC output was generating.

I am not into physics, especially anything phototic. Now you wanna talk strobe lights, thats a whole other story.

But, I was sold on these things when we held them under a standard LUX meter. For the actinics, it registered the same as standard VHO actinics--so whatever differential there is on the chromatic scale between contemporary lights and Luxeons the machine can't pick it up; and Id throw out a bet neither could an SPS specimen. I think they are useful so far for only nanos, Id want a dual 400MH setup for my "ideal" 75g reef!

 

[Anonymous]

The shark wrote:

How spendy are they? I mean at this point would it be more expensive than a $1500 halide/vho setup?

I believe Mike paid $40 for 4 of them.

 

[Anonymous]

But, for us tweaks who work with nanos/picos only these new LEDs lights are more preferable than a date with Raquel Welch (circa '68 of course).

Whatchoo talkin' bout brandon? Raquel is still a smokin-hottie!

 

[Bleeding Blue]

So I rigged up the power supply, and everything looks great. I still think that the leds will only be really good as a suppliment on my 6 gallon. I wanted to mount them in the hood today too, but m girlfriend was ready to leave work She just doesn't understand. I only ran them for a short time, but the seemed really bright, but really concentrated. I will post more when I mount them tomorrow. They would be brilliant for something right around the 1 gallon range. It would be really easy to retrofit four of the luxeon stars in the space that most of the one gallon kits use to house an incandecent light.

Mike

 

[Anonymous]

Could you tell me where to buy these?

4 for 40 is low enough for me to want to use is some of my other projects

Bryan

 

[brandon4291]

I think these guys are getting them from an internet site, but not sure. Go to Lumileds.com and maybe they will link you up, or they might point you to a retailer on the web somewhere. Bleeding Blue, I agree I think they will be great supplements and can eventually grow into a sole light source for your 6 gallon when the array gets larger enough (every top square inch pegged by them ~$1000! but when you do set them up like that it will be the baddest LED nano in the world. There is a gentleman on another board that has actually invested $1800 I think into an led array large enough to fully light a 30gallon reef. He did not use Luxeons though, he used radioslack big LED's but still the unit is bad to the bone. When the LED's are so dense they touch side by side, each little pinpoint source is grouped together and you get excellent penetrance, enough for a 6 gallon reef for sure. BTW< he also used some red and green patches in the array and has the circuits controlled by a computer, the electronics installation is outstanding as well. LED's are still too pricey!

 

[brandon4291]

John I should never assume although I frequently do...

haven't seen her in a while but Im sure at least she would still have that cave-girl streak in her.

B

 

[Anonymous]

Found em

1 - 5w with power supply for 49.95$

I think that is still too expensive I thought he was saying a total of 20 watts (4-5w) for 40

Bryan

 

[reefrancher]

I know I've bored some of you with my Lumiled 5 x 1w 4gallon nano but here's a pic how I wired mine:

More pics here: http://www.reefrancher.com/steve/nano/

Steve

 

[Bleeding Blue]

Guess you guys will have to take a look at the nano discussion. :lol:

http://reefs.org/phpBB2/viewtopic.php?p=261257#261257

Mike

 

[Will C1]

i cant see how you wired them. it looks like an alien has landed lol.

 

[PSAS-Jeff]

Not sure if this will help any of you, but here is a link to a site that sells some LED's! http://www.lc-led.com/ProductListing.jsp?idDepartment=1

A guy on another board bought the blue ones (500TB4D) and used 5 of them for a moonlight on a 90 Gallon Tank

 

[brandon4291]

Hey that referral helps a lot. This is a good link to LED's that can be used for accenting the driver elements--the multi-watters. It might look really interesting to combine an array of three or more of these colors along with the 5W daylight Luxeon, and try to fix the single source 5500K spectral output Robin has mentioned.

I have been thinking about what you've wrote for a few days. You are saying that the 5500K Luxeon LED rating comes from one source radiating 5500K lumens>whereas a MH bulb of the same Kelvin rating is a composite of many wavelengths, each acting to summarize as 5500K? Plants/animals tend to benefit from the many frequencies within this band... Good call Robin G.

This may explain why large/powerful arrays of standard white LEDs (before Luxeon) did not have consistent success with plants or corals--however, it became readily apparent that blue-emitting LEDS in the 470 nM range are quite useful. These LEDS (especially the luxeons) are an awesome miniature MH-like light source (given they are only 3/8 inch across). My friend's regal blue Luxeon 1w setup was almost blinding and output pure actinic light. These light sources with make the first breakthroughs with Nano aquariums and setups like moonlight additions, because they are still very expensive.