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From: davidc@vlsisj.VLSI.COM (David Chapman)
Newsgroups: sci.electronics
Subject: Re: "Super" capacitors == Batteries?
Summary: no, you can't
Keywords: supercaps, LEDs
Message-ID: <15244@vlsisj.VLSI.COM>
Date: 8 Jun 89 04:19:01 GMT
References: <1428@ndmath.UUCP>
Reply-To: davidc@vlsisj.UUCP (David Chapman)
Organization: VLSI Technology Inc., San Jose, CA
Lines: 19

In article <1428@ndmath.UUCP> milo@ndmath.UUCP (Greg Corson) writes:
>I've been noticing a lot of these so-called supercaps...capacitors with
>greater than 1 farad of capacitince.  Their main use seems to be a battery
>replacement for CMOS ram or clock circuit backup.
>
>My application is a farely simple one...I want to run a blinker-LED off of
>a supercap.  I was wondering if a 1 farad supercap would have enough juce to
>keep a blinker-LED (I'm talking about the kind with the blinker built-in, no
>external circuitry) going for 8 hours or so. 

You can't get enough power out of a supercap to light an LED.  As has been
noted before in an earlier thread, the internal resistance is too high.  CMOS
RAMs and clocks need only microamps to keep them going.  That's why these
things have found a market.
-- 
		David Chapman

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