LED domestic lighting

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Is there such an animal?
Mary
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Thank you. I asked because of a question on radio this afternoon - someone asked what to do with defunct low energy 'bulbs' and a panellist said that they could be an environmental hazard and implied that the future was in LEDs.
But I'd still be interested in trying them ... one ... :-)
Mary

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Mary Fisher wrote:

Ha! Nothing is a hazard if recycled correctly. You wait til the enviro-winers find out that LEDs contain arsenic!
FWIW, I think the future is in LEDs, but polymer based ones. These only exist in labs at the moment, but when high brightenss polymer LEDs make it into production, you'll see a whole range of new applications.
--
Grunff


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In uk.d-i-y, Grunff wrote:

Well, yes, but they'd only need to be replaced every few decades. The lamps, that is.
--
Mike Barnes

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Mike Barnes wrote:

I know that - you know that - but that is exactly the kind of logic that doesn't work on mindless enviro types.
--
Grunff


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http://www.absolutelylights.co.uk/ledtech.htm
--
BigWallop

http://basecuritysystems.no-ip.com
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Oh come on! That's not worthy of you.
It IS worthy of a mindless adolescent ...
Mary Who has several of those a grandchildren.

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I hadn't noticed but I believe you.
Mary

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Do you read Viz ?
The Roger Irrelevant strip ?
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We had *loads* of these at a previous place of employment. Large ones, small ones, round ones, square ones, red ones, blue ones, white ones... and they are *not* indestructible. The LEDs are arranged in a matrix, and a failure of just one will take out a whole row. Out of some 40 (ish?) in the ramp outside the main entrance, at the time I left there were a good 8 or 9 with a fault like this. In others the whole thing was off, but in this case it was usually the transformer which is easily replaced.
As for domestic suppliers, there are a few in a catalogue I have from a company called "QVS" (http://www.qvsdirect.co.uk/ ): 240V versions with 15 LEDs in white, blue, green, red, orange from 12 upwards. Also other versions of similar products including some outdoor (IP68) "floorlights" with 4 or 9 LEDs in blue or white for 22.50 or 29.95 and which require transformers.
As for power consumption, the 240V things are 1.8W, but quite how much illumination that gives is anyone's guess.
Hwyl!
M.
--
Martin Angove (it's Cornish for "Smith") - ARM/Digital SA110 RPC
See the Aber Valley -- http://www.tridwr.demon.co.uk/abervalley.html
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I'm not so sure. Once you start driving LEDs hard as a light source rather than just an indicator, their life span reduces dramatically.
--
*Make it idiot-proof and someone will make a better idiot.

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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My curiosity knows no bounds, it appears. When I bought one of those LED cycle lights, I hooked up a sillyscope to it and discovered that on the "steady" setting, it actually spent 3/4 of the time switched off. 100 Hz square wave mark to space 1:3. A clever way of stretching battery life. If you own one, you simply have to move it rapidly across your field of vision to demonstrate this.
John Schmitt
-- If you have nothing to say, or rather, something extremely stupid and obvious, say it, but in a 'plonking' tone of voice - i.e. roundly, but hollowly and dogmatically. - Stephen Potter
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driving them like this also means you can pump more current through them thus making them brighter (maybe this is the reason rather than saving battery life?)
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Dave wrote:

The mean brightness is still the same, since the mean current must be the same, because you can't leave the LED on at the current used when on or it will burn out. However driving them switch mode allows the circuit to run more efficiently which IS why they are pulsed.
Steve
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"Steve" wrote | >>My curiosity knows no bounds, it appears. When I bought one of | >>those LED cycle lights, I hooked up a sillyscope to it and | >>discovered that on the "steady" setting, it actually spent 3/4 of | >>the time switched off. 100 Hz square wave mark to space 1:3. | The mean brightness is still the same, since the mean current must be | the same, because you can't leave the LED on at the current used when on | or it will burn out. However driving them switch mode allows the circuit | to run more efficiently which IS why they are pulsed.
Is there a certain frequency above which this pulsed light is considered a continuous light and therefore acceptable as the continuous light required under the Road Traffic Act or whatever legislation says that flashing lights on bicycles are verboten?
Owain
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They're common as centre stop lights on cars. And as all the various tail lights and indicators on buses. Oh - and the taillights on my BMW. And of course there are HID headlamps (xenon) which aren't filament lamps either.
--
*60-year-old, one owner - needs parts, make offer

Dave Plowman snipped-for-privacy@argonet.co.uk London SW 12
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London SW 12

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Is the Act enforced?
Mary

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Actually LEDs get slightly more efficient at higher current, so the mean brightness is higher.
Furthermore, it appears that eyes don't perceive mean brightness, but perceive something which is between the mean and peak brightness, so a flashing light will appear brighter than a steady light of the same mean brightness (over some frequency range).
Neither of these effects is very large though. I've seen conflicting reports of which of these effects first resulted in pulsed operation of visible LEDs, although the high pulse current techneque was used to drive infra-red LEDs before visible LEDs were invented.

--
Andrew Gabriel

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Andrew Gabriel wrote:

That certainly used to be true, but again for the Luxeon jobbies we use, it ain't anymore.

Is this a medical fact ? In recent discussion on sci.elect.design, this effect was poo-poohed by several of the engineers in there whose opinions I would trust.
Steve
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