[OT] Anyone experienced with white LEDs?

From: Patrick Rigney <patrick_at_evocative.com>
Date: Tue Feb 4 20:27:01 2003


Reading off a convenient box of 60W bulbs, they produce 840 lumens, or 14
lumens per watt. This drops off slightly at lower wattages, so let's say
it's 480 lumens for a 40W bulb. But that's non-reflected (like a bulb
sitting in a socket with no reflector or shade), which isn't equivalent to
the way an LED puts out light... you need a reflector. In a perfect world
your reflector would focus 100% of the bulb's light, but in reality it will
reflect significantly less. Let's say it's 75% for a good reflector...
that's 360 lumens. There are about 12.6 lumens per candle, so that's about
28 candles. Given one of your examples below, the Super Flux LED at 20ma is
500 mcd (average), and 500mcd = 0.5 candles, so you'd need 56 of those
rascals to produce the 28 candles roughly equivalent to a 40W incandescent
with a reflector.

I think... :-) I'm drawing on a little memory from a long-dead photography


> -----Original Message-----
> From: cctalk-admin_at_classiccmp.org [mailto:cctalk-admin_at_classiccmp.org]On
> Behalf Of Roger Merchberger
> Sent: Tuesday, February 04, 2003 3:51 PM
> To: classiccmp_at_classiccmp.org
> Subject: [OT] Anyone experienced with white LEDs?
> I'm looking at building a personal lighting project possibly using white
> LEDs instead of regular miniature bulbs, and as I browsed the Mouser
> Example:
> P. 217, "Super Flux LED Lamps"
> The white one shows at 20mA it will put out 400-600 "Iv (mcd)"
> Any good websites w/info on how to figure out how many LEDs I'd need to
> make about a 40W (or more) lightbulb worth of light?
Received on Tue Feb 04 2003 - 20:27:01 GMT

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