A Monster LED Array For Irresponsible Fun 225
Tesladownunder writes "This huge LED is on steroids and then some. It is intended for use as a streetlight. It has a 7000 lumen output at 100W and will burn a hole in a CD case without focusing. And that's without the infrared that a halogen or discharge lamp has. Very efficient and low maintenance. Stronger than HID car headlights or a 500W halogen. Hit the site for lots of data and pics of it in action including burning and irresponsible bicycle luminosity. You'll want one to attach to your keyring, too."
Is it just me... (Score:5, Informative)
...or is that page totally fucked up in Firefox?
Firefox unfriendly (Score:4, Informative)
Possibly questionable design? (Score:5, Informative)
That being the case, I'd expect failure of any one emitter to be a serious issue. If, because of bad luck, thermal hot spots, moisture infiltration, or whatever, one of the emitters fails, it will either fail open, and break the circuit for all the other emitters it is in series with, or fail partly or wholly closed, and expose the emitters it is in series with to higher voltage. They will, then, start to die as well, until the whole string is dead.
Once an emitter goes, you aren't really going to be able to swap it out in a package like that, and I'd expect several of its buddies to swiftly follow it off this mortal coil.
Re:Light vs Heat (Score:4, Informative)
Re:Is it just me... (Score:5, Informative)
Re:Is it just me... (Score:5, Informative)
This is how you fix it real quick:
1. ctrl-A and cut the entire page out of Firefox. Paste it into Open Office.
2. ctrl-A to select all text and change the text color to black.
3. ctrl-A to select all text and go to the Table/Table Properties menu.
4. On that menu, change the right boundary of the table to something that is not a mile off the right side of the page.
You can fuckin' read it now.
Re:Sharks (Score:5, Informative)
I hate to ruin the party, but 70 lumens per watt is pretty terrible.
Sure, maybe that's a milestone for high power LED's, but it's not that useful compared to a low pressure sodium lamp that gets 160+ lpw. Also, both high pressure sodium and low pressure sodium lamps(2 most common street lamps) have a more pleasant spectrum on the eyes.
A pink or reddish tone is a lot better at illuminating streets than a faux white spectrum that has high peaks in the blue region.
Burn a hole in that site (Score:5, Informative)
<meta name="GENERATOR" content="Microsoft FrontPage 6.0">
Re:Possibly questionable design? (Score:5, Informative)
That said, LEDs are pretty robust, and tend to fail open circuit rather than closed circuit so if individual LEDs blow in a series chain, they don't destroy others with them. A few years back I did a lot of work with similar arrays to provide controlled lighting for machine vision - you can overdrive them by ridiculous amounts as long as it's only for a very short time (although they do 'wear out' faster with this treatment). We had no troubles passing over 10 times the rated current through standard 'ultrabright' LEDs for up to 10-20 milliseconds.
Re:Another use (Score:5, Informative)
I personally enjoy his gaming [tesladownunder.com] references [tesladownunder.com], but there's something for everyone.
Just... wow. His curiosity and expanse/depth of testing is simply baffling....
No wonder he didn't have time to design a website, he's not interested in boring numbers and code; he enjoys placing himself in, what I would call, risky situations [tesladownunder.com].
Re:Sharks (Score:5, Informative)
That's the problem with the lumen scale. The most efficient LEDs are red and blue. The lumens scale weighs green an order of magnitude more than red and blue because it's based on the sensitivity of the human eye. In LEDs, there's a so-called "green gap"; there are no efficient green LEDs, which is right where we need it the most when it comes to lighting that our eyes can see effectively.
Now, for plants, it's a different story. Plants love red and blue, which is what LEDs do best. But really, we're supposed to be impressed by 100W of LEDs? I have 200W of LEDs in the room next to me (I start my garden seedlings under LED light). A standard UFO grow light is 90W, and many dozens of them sell daily on Ebay alone. What the heck are they doing spending $500 AUD on only 100W of LEDs? I got my UFO for $140-some; that took watching for a few weeks, but you can "Buy It Now" on them generally for $225. The rest of my LEDs are LED xmas lights, which are even cheaper (although the UFO seems more effective... pretty nice product, IMHO).
Gallium Nitride (Score:5, Informative)
The source material for this LED is Gallium Nitride(GaN). Its quite a revolutionary semiconductor material developed first by Shuji Nakamura in the 90s at Nichia Corporation, Japan.
It has a multitude of applications in different fields - optoelectronics, HF microwave communications and anti-radiation hardening for space vehicles.
These LEDs are very efficient in the sense that they consume less power and have more lumen output. And they die out gradually, unlike traditonal sources of lights like tubes/bulbs which will immediately fuse off. Which explains why they are robust alternatives for street lights, traffic signals, etc. They need less power, less maintainance and due to their solid state nature are quite tough materials.
Lot of research has been conducted on them. Here are couple of leading centres for GaN research -
UCSB - http://my.ece.ucsb.edu/mishra/studygane.htm [ucsb.edu]
Cambridge(UK) - http://www.msm.cam.ac.uk/GaN/ [cam.ac.uk]
There is an online journal of Nitride Semiconductor research not updated much now, but very useful -
http://nsr.mij.mrs.org/ [mrs.org]
Check it out.
Many traffic light signals use these LEDs already across the world nowadays for less power consumption. Watch out for few in your city.
I remember back in my college days that it was already being touted as a replacement for the century+ old incandescent bulb. Buzz and hype I guess but still with a lot of substance.
Cheers!
Re:Is it just me... (Score:3, Informative)
Re:Possibly questionable design? (Score:4, Informative)
Re:Is it just me... (Score:3, Informative)
here is a better solution:
In firefox with the Web Developer extension, click the "Linearize Page" under Miscellanious.
you can now read the page
Ho-Hum You need to see a REAL LED Array 20,000L (Score:2, Informative)
Re:Is it just me... (Score:2, Informative)
Re:Sharks (Score:4, Informative)
What?
160lpw is for the most efficient lamps currently known. So, yes, 70lpw is impressive. Also, the 160lpw low pressure sodium lamps don't have a "pink or reddish tone" they are very orange (actually two orange lines very close together). The high pressure sodium lamps, the white ones with the pinkish tone are more like 100lpw, in which case, the LED is quire close.
Re:Sharks (Score:2, Informative)
The "flashing neon sign" effect is unlikely without a malfunctioning LED control. While you refer to negligible startup and stop times, I don't think you understand just how small they are. Many dimmable LED lights don't actually dim the LED at all, instead they turn the LED on and off around a thousand times per second - much faster than the eye can distinguish. This has two major advantages: the on voltage is constant and the duty cycle allows easier adjustment of brightness.
With a constant on voltage, you can set it to the most efficient voltage to produce light or the easiest voltage for your power source to produce and it will stay pretty close no matter how much or how little light you want from it. If you compare it to old style incandescent bulbs, at low voltages they start putting out mostly non-visible light wavelengths and their color shifts dramatically. The heat of an LED will shift the amount of on current slightly, but it should be a fairly small effect in a properly controlled circuit (in an improperly controlled one, you end up with fried LEDs as the heat pulls more current which makes more heat).
The duty cycle adjustment also allows much more consistent light output. LED light output is mostly dependent on current, which is exponentially related to its voltage. A small shift in voltage can thus result in a huge shift in current and thus light output. Good current sources aren't all that easy to produce, especially variable current sources (FETs are often modeled as current sources, but the model isn't perfect). However, by varying how much time the LED spends turned on vs. turned off you get a dang close to linear function of brightness. If the LED spends all its time on, its 100% of its possible brightness. If it spends half of its time on, it is 50% of its possible brightness. If it spends 12.5% of its time turned on... you get the idea.
Of course, there can be slight flickering issues if you don't turn the LED on and off fast enough. And the control circuitry does draw some small amount of power. And the heat of 100% on vs. 25% on will cause some drift. And... well, lots of small things. Its still a heck of a lot easier than getting a variable current source properly tuned to the LED's forward bias voltage and the in-line resistance, especially including all manufacturing variances.
Re:Is it just me... (Score:2, Informative)
Page fixed. (Score:2, Informative)
Re:Another use (Score:3, Informative)
You can be a geek without being a computer geek. Maybe his thing is electronics and not coding.
Then why is he making webpages?
By the way, webpages were _invented_ for physicists who are not coders to have an easy-to-use markup language.
Re:Sharks (Score:3, Informative)
Minor quibble... Low pressure sodium is preferred by observatories. High pressure sodium has huge bands all over the spectrum, while low pressure only has a single strong band and a bunch of weak ones.