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From: tomb@hplsla.HP.COM (Tom Bruhns)
Newsgroups: sci.electronics
Subject: Re: HV Cap Fun!
Message-ID: <5170033@hplsla.HP.COM>
Date: 30 May 89 16:10:09 GMT
References: <4924@m2c.M2C.ORG>
Organization: HP Lake Stevens, WA
Lines: 24

dhesi@bsu-cs.bsu.edu (Rahul Dhesi) writes:
>[about energy storage by capacitors]
>
>I've always been very, very careful around capacitors ever since I
>discovered to my amazement that not only can they hold a charge for a
>long time, but also that:  You can discharge some electrolytic
>capatitors, remove the short circuit, and after a few minutes the
>capacitor regains a smaller charge.
>-- 

Electrolytics are notorious for this (some folk call it "soakage",
or "dielectric absorption").  But be aware that you aren't safe
from this effect just because you capacitor is not an electrolytic.
Other caps will do it, too.

Larry's tale reminded me of the FCC inspector that used to go around
this area doing broadcast station inspections.  He would open the
doors on the back of the transmitter to "make sure" it went off the
air like it's supposed to (interlocks working).  He quit doing it,
so the story goes, when he came across a transmitter where the
interlocks not only really _were_ working but where they dropped a
direct short across all the big caps.  It was apparently a bit too
much of a surprise for him (he survived OK, but quit checking in
quite so dramatic a way...).