Re: Reducing Inductance In Caps

To: tesla-at-pupman-dot-com
Subject: Re: Reducing Inductance In Caps
From: Esondrmn-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Thu, 17 Feb 2000 17:13:06 -0700
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

In a message dated 2/17/00 2:13:10 AM Pacific Standard Time, tesla-at-pupman-dot-com 
writes:

 - snip -
 > Hi Bill...
 > 
 > many of the professional cap companies use this method    it reduces the
 > charge /discharge time by a few nanoseconds  ( it reduces the inductance
 > in the cap) 
 > 
 > not to sure what you mean by self resonance tho    if you are refering
 > to the resonance between the power supply and the main cap ...   i dont
 > think extended foil design makes a difference there  
 > 
 > Scot D
 > 
 > 

 I had read that rolled caps self resonate, because they are a cap
 and a coil all at the same time.  However now I understand they must 
 have really meant that rolled caps have higher inductance.  There
 by slowing the charging and discharging time, that makes sense.

 Now the question is if the inductance slows the charging and
 discharging, would not that change the overall freq in the primary?

 For TC use is it better to use extended foil design or the non
 extended foil design in rolled caps?

 Does this inductance change the overall capacitance?

 Does it change the number of turns needed on the primary?

 Many Thanks,
 Bill Parn
  >>
Bill,

Many of us have built rolled poly caps.  They work just fine in Tesla coil 
service.  While they certainly do have more internal inductance than 
commercial end foil or flat plate caps, I think the performance difference is 
very small.  I have not noticed any significant difference in calculated 
values (frequency, expected primary taping point, etc.) v.s. actual 
performance.  I have built three of these and considering time involved, 
money spent, size, weight and ability to repair, I would definitely build MMC 
caps next time.

Ed Sonderman