Re: Electrolytic Caps for AC use

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "john cooper" <tesla@xxxxxxxxxxxxxx>

Ahhhhh, now here's something I know a bit about.  Electrolytic caps have a 
definite shelf-life.  10 years old is specious.  I buy and sell components 
and any electrolytic over four or five years old is suspect.  They can be 
'rehabilitated' but it's a pain in the ass.  The process is called 
're-forming', wherein you slowly introduce a current and increase it to its 
spec.  Takes time, like I mentioned, a real pain.  One of the main problems 
is that the 'can' isn't always totally sealed and they can dry out a 
bit.  So you measure them before and after this process (and the specified 
tolerence usually goes to hell).  As a rule I won't buy ANY electrolytic 
older than 4 years old.  I've gotten grief from purveyors of such older 
caps when I tell them that they need to be thrown in the trash once they 
tell me the date code.  In the real world who has the time or expertise to 
properly re-form an electrolytic?  Not many, and we'll just toss them 
unless they're obsolete with a demand, b
 ut that has never happened.

However, some electrolytics have to be worthy of this process (the eternal 
optimist that I am), contact me for the details if it's truly worth your 
effort and you can't locate the details elsewhere.

Cheers,

John F. Cooper
Irvine, CA
www.Tesla-Coil.com
www.FrankensteinsLab.com



---------- Original Message ----------------------------------
From: "Tesla list" <tesla@xxxxxxxxxx>
Date:  Mon, 06 Dec 2004 22:36:53 -0700

>Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>
>
>Electrolytic caps will explode if attached to full-wave AC. Luckily mine
>were smallish 25v 4700uF. Puts out some nasty smoke that's worse than
>burning hair/sulphur, but a nice bang.
>
>Mike
>----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
>To: <tesla@xxxxxxxxxx>
>Sent: Monday, December 06, 2004 9:31 PM
>Subject: Electrolytic Caps for AC use
>
>
>>Original poster: Harvey Norris <harvich@xxxxxxxxx>
>>
>>I have heard there is a way to adapt "DC" electrolytic
>>caps for use in AC by wiring a combination in a
>>certain way, any truth to this? I need large banks of
>>these in the 500 uf range, but conventional caps would
>>be way too expensive.. I also heard they can explode
>>if improperly connected to AC, anyone have experience
>>there? Will they gradually loose capacity rating over
>>time, since they are constructed like batteries,> do they have a limited
>>shelf life? Mine are about 10
>>years old.
>>HDN
>>
>>
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