Article View: sci.electronics
Article #19846Re: speaking of LEDs
From: Carl Lowenstein
Date: Fri, 30 Sep 1988 16:58
Date: Fri, 30 Sep 1988 16:58
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In article <7200014@silver> commgrp@silver.bacs.indiana.edu writes:
>Some cave-explorer friends are experimenting with the new LEDs for
>emergency light sources: Two LEDs, each in series with a 33-ohm
>resistor, connected to two alkaline AA-cells, will make enough light
>to get out of the cave, for 24 hours.
>--
>Frank
>reid@gold.bacs.indiana.edu
Why not connect the two LEDs in series and use a smaller resistor.
Don't use the battery energy heating a resistor when you could be using
it to make LED light.
Answer of sorts to the question above: the forward drop across the LED
is too great. About 2 volts for green. Revise the question: How
about 3 alkaline cells and 2 LEDs. Should be a better match to the
problem, at a 50% weight penalty.
--
carl lowenstein marine physical lab u.c. san diego
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Path: arc1-ca.pugleaf.net!utzoo!attcan!uunet!seismo!sundc!pitstop!sun!amdcad!ames!ucsd!sdcc6!mplvax!cdl From: cdl@mplvax.nosc.MIL (Carl Lowenstein) Newsgroups: sci.electronics Subject: Re: speaking of LEDs Message-ID: <779@mplvax.nosc.MIL> Date: 30 Sep 88 16:58:55 GMT References: <491@ole.UUCP> <7200014@silver> Reply-To: cdl@mplvax.ucsd.edu.UUCP (Carl Lowenstein) Organization: U.C. San Diego, Marine Physical Laboratory Lines: 21