To get the light levels you need for domestic lighting you have to drive them very hard. Careful thermal management is required and efficiency isn't nearly as great as some would have you believe.
MBQ
The driver circuitry can be 90+% efficient if designed corectly, just like any other switch mode converter. The LEDs themselves dissipate a lot of power as heat.
MBQ
The LEDs themselves dissipate a
Umm ... is that not why we were forced to get rid of incandescents. I could never quite understand the logic of that as that heat just contributed to the house heating. No one ever complained that his house was too hot because the lights were on !!
Rob
The energy spectrum of a hot body (tungsten filament in this case) is determined by one thing only: its temperature. Incandescents can never be hot enough to ensure that most of their energy is at visible wavelengths. They'd (unsurprisingly) have to be as hot as the sun's surface (6k).
Personally, in the summer I don't need the extra heat.
That's how they modify the base colour. Which with 'white' types is usually blue.
In article , The Natural Philosopher writes
I think white LEDs do. They're actually blue LEDs with a phosphor to convert the light to white, which is why they often look blue-ish.
In article , Dave Plowman (News) writes
If the original light is blue, why did it take so long for blue LEDs to come out? (You can't get away from them now.)
They've been around for years (20+ at least) but were very expensive compared to the usual red. Now there's a mass market for blue (to make white ones), you can pick up blue ones for a lot less.
MBQ
It's all relative. A LED light will still be better than incandescent, just don't expect it to run cool.
MBQ
Can't think of any light source that doesn't generate some heat. It would have to be 100% efficient not to. Tungsten start off at such a low efficiency that just about anything more modern will be better. Efficiency wise - not necessarily in light quality.
Depends how the light is generated. With incandescent you just heat something up whereupon it emits black-body radiation - and it's 100% efficient at doing *that*. You're just complaining because the radiation peak for your tungsten blub is in the infra-red, rather than in the visible. Of course, in the latter case there'd be significant UV as well.
LEDs (and lasers) use a different principle anyway for their light generation, which is why they tend to be monochromatic.
That last bit is the key factor, unless the light is good and the cost reasonable(*) no matter how little power they use they won't be taken up.
(*) On a PAR with mid range CFLs, not the 99p for two supermarket offerings...
White ones do, others have been saying the light from the junctions is blue. I think in the case of white LEDs it's actually somewhere in the UV range rather than visible blue but I haven't googled... B-)
So trichromatic. Not sure that is much better than monochromatic.
... but not better than a CFL, it would seem.
Blue LED been around since early 80`s in silicon carbiide form, couple problems , output was tiny and maunfacturing yield was like 1 in
10,000, Siemens offered a blue SiC LED , about 80 quid each for the 5 mm in late 80s.Big breakthrogh is down to one man in the late 90s, Shuji Nakamura who developed with aid of a lab assistant and funding of his employers, Nichia, Galium Arsenide blue LEDs with far better output and yield.
Nichia`s main buiness being CRT and lighting phosphors Mr Nakamura went on to develop the white LED.
Cheers Adam
And in the summer, I don't need as much lighting!
I agree that incandescents waste energy, but the amount people claim is lost per year is overstated, as we generally use the lights much more in the colder, darker parts of the year than the lighter, warmer parts.
SteveW
Their Led is no more efficent than a Cfl, it is a higher Kelvin and harsher on the eyes than 2700K or what incandesants or Soft White Cfls are. The price of that product is about what I can get 15 Cfls for with a 9 yr warranty, its not outdoor rated. Its an overpriced overhyped product that doesnt compete with quality Cfls in cost of lifespan, its a waste of money for suckers until the price drops 95%. Sure th Leds will last, but that electronics package that powers it only time will tell if it can survive surges and real world temps and humiditys. So far what I have seen Fails on all points. Buy a Cfl till things change in a few years, Marketing hype, Marketing and Sales, is all you are getting so far.
I bought a mains LED bulb for a fitting which gets left on a great deal. It blew up in a big way in less time than the tungsten normally lasted.
On May 15, 9:54=A0am, "Dave Plowman (News)" wrote:.
In my lounge I have 8 GU10 bulbs on two adjustable spotlight fittings. Ok the 50watt bulbs supplied are dimmable, but I have the 80led units courtesy of a HK seller on ebay. I personally have become used to the light which is much whiter/colder than the orange glow of the hallway cfl. But 20 watts compared to 400 watts is the important thing for me especially as not everyone turns the lights out when they leave the room. Now if they would just turn the tv off....
Dave.
Well, you're obviously happy with the poor colour and the lower intensity. Others may not be.
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