Path: utzoo!attcan!uunet!tektronix!tekcae!vice!keithl
From: keithl@vice.ICO.TEK.COM (Keith Lofstrom)
Newsgroups: sci.electronics
Subject: Re: capacitance of batteries
Message-ID: <3061@vice.ICO.TEK.COM>
Date: 22 Nov 88 19:32:06 GMT
References: <1988Nov13.001657.21990@utzoo.uucp> <16750005@hpfcdj.HP.COM>
Reply-To: keithl@vice.ICO.TEK.COM (Keith Lofstrom)
Organization: Tektronix, Inc., Beaverton,  OR.
Lines: 24

In article <16750005@hpfcdj.HP.COM> myers@hpfcdj.HP.COM (Bob Myers) writes:

>And again I say, nay, yon device is not necessarily a capacitor, simply
>because thou canst reduce an AC component with it!  ...

>Question the second: If the battery in question is really acting as a big
>capacitor, comment on the expected phase of the AC current through it,
>relative to that of the AC voltage applied across it.  Hmmmmm?

If I put a 1 Hz signal across a battery, I mostly see a resistor.  If I
put a 1 milliHertz signal across a battery, I see current/voltage waveforms
that look like a capacitor.   Shift the frequencies up by 1000, and the 
same holds true for a typical large electrolytic.  In the frequency ranges
I usually work in, they are both lossy inductors, and I use ceramic chipcaps,
which look like open circuits at 1Hz.  

These are all useful in different regimes, and all resemble each other to
some small extent.



-- 
Keith Lofstrom   ...!tektronix!vice!keithl   keithl@vice.TEK.COM
MS 59-316, Tektronix, PO 500, Beaverton OR 97077  (503)-627-4052