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[AMPS] resistors

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Subject: [AMPS] resistors
From: (Rich Measures)
Date: Wed, 24 Feb 1999 23:58:37 -0800

>>>>>Ä  What mechanism recharges the capacitor?
>>>>>An incomplete discharge. Something very easy to do for an inexperienced
>>>>>?  Bzzzzzt.  You said recharge.
>>>>The mechanisms causing apparent recharge were discussed in good detail
>>>>by Bob Pease of NatSemi in Electronics magazine (I think) a few months
>>>>ago. I'll post a reference when I find it.

>The mechanism that causes this is dielectric absorption.  The model for a
>real capacitor includes many series resistors and capacitors that are then in 
parallel with
>the primary capacitor value.  When you short out a capacator, it takes a 
>(depending on the type of capacitor) to discharge all of the stored charge  
This is why
>you can short out a capacitor several times before the charge is depleted.  

?  Agreed, Eric.  I have tried it.  However, the case in question with 
Carl Heuther was for a capacitor that is paralleled with a 200-ohm per 
volt bleeder resistor.  

> To see this, charge up an electrolytic cap and then
>short across its terminals....wait a few seconds and do it again.  You
>should see a spark.   I'm not sure how much
>of this you would see with a good oil filled cap though.

?  I found that an oil-filled capacitors, as well as electrolytic 
capacitors exhibit the phenomenon.    

- cheers - 
>Eric KR7A


R. L. Measures, 805-386-3734, AG6K,  

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