From: John Woodgate
Subject: Re: linear power supply noise questions
Date: Wed, 13 Nov 2002 07:11:39 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Wed, 13 Nov 2002 10:28:26 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Ben Bradley wrote (in <firstname.lastname@example.org
>) about 'linear power supply noise questions', on Tue, 12 Nov 2002:
> Actually I'm pretty sure there's some real experience that says
>electrolytics without significant voltage (such as at least half their
>rated voltage) on them will eventually lose their 'forming' and lose
>most of their capacitance.
It doesn't make sense. If the oxide layer became thinner, the
capacitance would increase, not decrease. I suspect that the 'effect' is
actually normal drying-out, that affects most electrolytic caps after
There are millions of small electrolytic caps in use which have next to
no d.c. bias applied. It doesn't cause a significant problem.
For reverse bias, keep it well below 1 V for prudence.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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