At 12:52 AM 7/12/01 +1000, you wrote:
>
>Hi Spehro, if you haven't done so yet have a
>play with a 6000mCd white led. I have one running
>at only half power (25mA) that is a very effective
>flashlight.

The best ones I see at Digikey are ~2300mcd "typical"
at 20mA. For about $3 US each. So, if they are linear
they'd be around 6000mcd at 50mA. I designed a white-
LED microscope ring illuminator for a friend, but
I'll have to wait till I get out to California again
to actually see it in action. ;-)

>I can't believe Philips' claims of "not efficient yet"
>i'm sure a hundred of these leds running from 240vac
>would still only draw 50mA and give as much (or more)
>light as a 60w bulb drawing 250mA.

I think your order of magnitude is right. But an 11W
flourescent is about as bright too and is very cheap.

>I really don't see an efficiency issue, just an initial
>cost issue.

Efficiency would get it into leading edge applications
such as laptop backlights where cost isn't as big a
factor. Small size, low voltage and low power at
reasonable efficiency is getting them into many
specialized apps now.
But high cost will kill consumer applications
for sure. $15 retail is too much for many people, and if
there is no operating cost savings relative to CF, then
what is the unique selling proposition?

>And they make awesome "point lights" for looking down
>in PCB crevices etc. Mine give more light at 2 inches
>than a 40w 4 foot fluoro tube at 2". One of these days
>I will take a picture of our point lights and put it
>up on the net; 5x 110mAh NiCd, a stick, a switch,
>a resistor and a white led.
>One of the most useful tools I have ever built.

I'd like to see that. Sounds like a good idea. Maybe I'll
use one or two (depending if I feel like making a SMPS)
of those NiMH battery packs I picked up in Tucson and
make one.

I'd really like to have one of those lights that the
dentists use, though.

Best regards,
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
Contributions invited->The AVR-gcc FAQ is at: http://www.bluecollarlinux.com
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