From: "Bill Sloman"
Subject: Re: maximum reverse voltage allowed on electrolytic caps?
Date: Wed, 13 Nov 2002 23:02:35 +0100
Organization: Planet Internet
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NNTP-Posting-Date: 13 Nov 2002 22:02:28 GMT
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"Spehro Pefhany" wrote in message
> On Wed, 13 Nov 2002 18:18:24 +0000 (UTC), the renowned
> Baz@NOSPAMporteraudio.co.uk (Barry E Porter) wrote:
> >Depends upon how long it's there. Some makes of electrolytic (e.g
> >Philips) don't even like no bias voltage for any length of time, and
> >turn into short circuits after about 6 months of continuous use
> How does the capacitor know that the item is being used
> continuously rather than just sitting on the shelf, if the bias
> voltage is zero?
It doesn't. If you take old capacitors out of store, it is always a good
idea to "re-form" them by hooking them up to a DC source close to their
rated voltage, via a resistor that will drop their rated leakage current at
One of the legends at Geoge Kent in the 1970's was about a steel mill that
had a couple of racks of George Kent analogue process controllers, which had
been ordered and installed several years before they were needed. When they
were finally powered up, most of the reservoir capacitors blew up. The
customer was not impressed, and even less impressed to learn that the
controllers were out of guarantee.
Bill Sloman, Nijmegen