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12/08/09
Also, as christmas lights, the snow buries them and they won't melt themselves free like the incandescent ones will :(
12/08/09
Better ones have full-wave bridge rectifiers that cause it to flicker at 120hz.
Better ones still put a capacitor so they don't go "off" so often, and hardly flicker.
12/08/09
12/08/09
All of the true LEDs I've seen emit a very specific wavelength though, so even the mixed white lights are made of a certain red, a certain green, and a certain blue. Hopefully we can have a less homogenous mix of quantum dots that will shine various colors at once.
At best though, maybe we'll end up with a low energy lighting technology that doesn't leak UV light...
12/08/09
That doesn't leak UV light? Don't you mean IR? That's what incandescent, halogen, and even (to a lesser extent) flourescent lights produce as a waste product. The only LEDs that I've seen that produce UV light do it with purpose. See, at Brickworld, Brickarms packed a bunch of tri-LED flashlights in with a pack of transparent weapons to be handed out in the registration kits. There was one red LED that was hooked up to a signal button (only on when the button was held down), and there were two other LEDs that were hooked up to a 3-way button. Push it once and a plain white LED turns on. Push it a second time, and the white LED turns off while the third LED turns on and puts out what appears, at first, to be in the blue/violet spectrum. However, if you point it at certain LEGO parts, you realize that it's actually a black-light LED, as it makes those parts glow really bright. So, really, it's just leaking into the visible spectrum.
12/08/09
12/09/09
I said the IR was a waste product, not the intended result. Even flourescent light tubes get pretty warm to the touch, but the desired output is UV light because that makes the powder coating the inside of the tube glow with visible light.
I have also never heard of an LED that emits UV light with the purpose of flourescing a different material to produce visible light. I'd think that, given the small size of a typical LED, the light produced in this manner would be barely noticable.
12/09/09
[www.olympusmicro.com]
I have only read about UV-to-white LEDs. Wikipedia offers this about them:
White LEDs can also be made by coating near ultraviolet (NUV) emitting LEDs with a mixture of high efficiency europium-based red and blue emitting phosphors plus green emitting copper and aluminium doped zinc sulfide (ZnS:Cu, Al). This is a method analogous to the way fluorescent lamps work. This method is less efficient than the blue LED with YAG:Ce phosphor, as the Stokes shift is larger and more energy is therefore converted to heat, but yields light with better spectral characteristics, which render color better. Due to the higher radiative output of the ultraviolet LEDs than of the blue ones, both approaches offer comparable brightness. Another concern is that UV light may leak from a malfunctioning light source and cause harm to human eyes or skin.
I am disappointed that energy efficient lighting and UV leakage seem to go hand in hand a lot of times, but I'd imagine it will improve in the next several years.
12/07/09
"I can't do that Captain, I'm giving her all she's got!"
12/07/09
12/01/09
I do believe in LEDs though, but I'd rather see a more complete shift.
In theater and industrial events we use RGB LED fixtures to mix color and create (almost) whatever we want. For the home though I'd love to see LEDs that mix color temperature (these exist in architecture, but are less prevalent). Imagine if every lamp had a warm circuit and a cool circuit, and one could control this relationship through a two channel dimmer on the wall. This would be ideal - Crisp bright white for daytime use, or technical work, warm comforting light for living. With the right circuitry you could even piggy back the control signal on the AC line so that you wouldn't have to re-wire your house. How cool is that?
Right now I accomplish this at home through a combination of many light sources and lots of switches (I AM a lighting designer - and a geeky one at that) but it would be nice to have a more elegant solution to the problem.
12/01/09
12/01/09
12/01/09
12/01/09
You know they sell the swirly CFLs in incandescent color temperatures? I am in a room lit by one right now.
12/01/09
12/01/09
They name them tricky things...best bet is to buy a few until you find the right one and then write it down and keep the packaging...I think they usually call them "soft white" sort of a misnomer...
12/02/09
Warm white fluorescents have a lower kelvin rating than their cooler counterparts.
12/02/09
Very true...do they write the kelvins on the box? Technically orange is much cooler than blue so the rating is lower..
12/02/09
Commercial grade and dedicated ballast lamps will give a color of 2700k, 3000k, 3500k, 4100k, 5000k, or daylight (6000k)- note day light is NOT warm. People always think that 'daylight' is like the sun which is yellow- not the case. Daylight is almost a bluish hue.
If you're at a place like costco or walmart, be sure to read the box carefully for a color spec.
11/30/09
LED FTW
11/30/09
What is it about our own perceptions that refuses to acknowledge a blue world? We want to live and love in that yellowish world! Our own yellow (but not really :D) sun?
11/30/09
11/30/09
#Speakout
11/30/09
Anyway I agree the old bulb is much better light for most occations, CFL has come close the last couple of years tho.
11/30/09
11/30/09
12/01/09
12/01/09
11/30/09
11/30/09
It may necessitate picking up some familiarity with lighting industry lingo, but you might want to look at the rounds of the CALiPER testing program (as run by the US DOE). They buy, test and then tear to shreds the vast majority of LED lightbub replacements the reports that get published. There’s unfortunately a lot of crap on the market.
[www1.eere.energy.gov]
The DOE (EnergyStar) maintains lists of LED products which have been tested by independent labs and approved as "pretty decent". Unfortunately no home-use replacement bulbs are on the list at this time, only complete LED packages (fixture + lamp,etc) as one might install during a renovation or construction of a new home. Check out a CREE LR6, your worries will melt away.
[www.energystar.gov]
11/30/09
Headlights (Audi), street lights (San Francisco just implemented some) and a variety of places where we take light for granted (public restrooms, etc) they work wonders- just not in my living room.
11/30/09
11/30/09
Now that no one prints emails to read anymore, we are just groping around most of the time. It has led to some uncomfortable lectures around "harassment"...but we are getting off-topic.
11/30/09
I've been in commercial and residential lighting for a few years now. LEDs are really starting to hit the main stream- no longer specialty crap.
There are problems though- every LED lamp we sell, we know we won't get that business back for a LONG time (lighting noobs- lamp means "bulb", not a fixture)
Other problems with LED are light output similar to fluorescent, and odd dimming dynamics. Another BIG problem is that most all are low voltage running at 12v- not a problem- but when existing fixtures have transformers meant to power lamps at 35 or 50 watts, many transformers require minimum draws, a number far greater than the pitiful amount the LEDS require. (usually 20w, and LEDs run 3-10w.)
Other problems with LEDs- they are ugly as can be. The diodes are SO sensitive to heat that if they get even remotely hot, they die- end of story. That's why they have those GIANT heat sinks attached to them. I'm here in San Francisco where it doesn't get too hot, but I can't imagine someone in an Arizona summer trying to run one of these.
In a market that's directed primarily towards recessed lighting, LEDs are GREAT. you don't see those lamps one way or another, so make them high efficacy and bright. But with that, you also don't get directionality out of the LED lights- so PAR and MR16s will always need to be there. LED MR16s are around, some better than others, but the good ones cost upwards of $70/ea.
I think the big determining factor for all this new tech is economic. Can you convince the public to drop $20 on an LED A lamp that looks ugly as sin, even though they'll save a LOT of money over its lifespan over a standard A19? Or is the American "immediate gratification" too strong. For commercial, government and architectural stuff, LED is the future. For residential, not so much... yet.
ps- Osram makes amazing lamps, but they are the BMW of them. You pay a LOT of money for their long lasting halogen stuff. Lots of lamp manufacturers even talk down on their LED stuff to keep you buying the less efficient stuff.