Article View: sci.electronics
Article #19860Re: speaking of LEDs
From: Neal Sedell
Date: Tue, 04 Oct 1988 20:35
Date: Tue, 04 Oct 1988 20:35
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Sorry to transpose this response with another article, but our mailer has been extremely brain-damaged for quite a while now. It used to be almost perfect and I felt sorry for those less fortunate... >>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. > >Why not connect the two LEDs in series and use a smaller resistor. Well, since we're talking about an emergency light source, the key-word is RELIABILITY, not efficiency! >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. Same here. Who needs another 50% probability of battery failure??? And yes, I'm glad we seem to have the green/red issue resolved... -- Neal Sedell
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arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!tektronix!tekgen!tekigm2!nealsReferences:
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!bloom-beacon!mit-eddie!uw-beaver!tektronix!tekgen!tekigm2!neals From: neals@tekigm2.TEK.COM (Neal Sedell) Newsgroups: sci.electronics Subject: Re: speaking of LEDs Message-ID: <3593@tekigm2.TEK.COM> Date: 4 Oct 88 20:35:12 GMT References: <1988Oct2.053515.18004@utzoo.uucp> <1652@eos.UUCP> Reply-To: neals@tekigm2.TEK.COM (Neal Sedell) Organization: Tektronix, Inc., Vancouver, USA Lines: 24