AL A. wrote:
Hi all,
I know this is not strictly on topic, but this crew seems to know something
about everythig, so here goes:

I am looking to build a "task" lamp (think dentist-type light) that uses
high output white LEDs for a friend who often does
work for extended periods of time in very remote places. I was looking at
the NTE electronics "lightwave" flashlights
http://www.nteinc.com/lightwave/ and they claim that they have circuitry
that makes it possible to run one of the 10
led lights for 24 days, continuously, on 3 D cells.

Any idea how they accomplish that? Most of the high output LEDs I have seen
seem to want to run between 20 and 40 mA
current draw. Given the amp-hour ratings I find for D cells, I don't see how
that would work out. Do they modulate the power to the LEDs
in some way that helps extend the battery life so dramatically?

Yes, it's the wonder of marketing.
You time it until you can't see it under an image intensifier in a pitch
black cave.
And then you quote the brightness at the start.

--
http://inquisitor.i.am/ | | Ian Stirling.
---------------------------+-------------------------+--------------------------
All I want is a warm bed, a kind word and unlimited power -- Ashleigh Brilliant.