RE: Possible Sale CD .15 caps - new, inductance ?

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>

Thanks Steve,

That makes good sense. I overlooked the paralling of 18 stings as a minus,
that almost brings us to the inductance of one string! So I'll be soldering
396 of them! 18X22=396caps. I'm expecting 26 from Dr.R. + 126 from Rell in a
month. The stings will be ~ 50 inches long. Maybe I'll zig zag them or have
them go up and down so the primary would not interact with them,
perpendicular to the flux field. Ideas anyone?

Jim Mora
Yikes that a $1000 worth of caps!

-----Original Message-----
From: Tesla list [mailto:tesla@xxxxxxxxxx]
Sent: Monday, November 06, 2006 11:05 AM
To: tesla@xxxxxxxxxx
Subject: Re: Possible Sale CD .15 caps - new, inductance ?

Original poster: "Steve Ward" <steve.ward@xxxxxxxxx>

For a SGTC where large Lp and low coupling coefficients are the norm,
the inductance added from the MMC is small.  Each cap has an ESL of
around 30nH if i remember.  Lets call it 60nH with the leads.  You
would then be looking at about 1.32uH (from 1 string).  BUT, you have
18 parallel strings.  Provided they were completely isolated (no
coupling/mutual inductance) you would get 1.32uH/18.  But since the
strings will be close to eachother, you will only get a slight
reduction in inductance.  It should be noted that the 1.32uH is
assuming the "loop back" from one end of the string to the other
contains zero area... unlikely in practice.  Bottom line is, your MMC
shouldnt exhibit more than a few uH of inductance, which should be
fairly small compared to the primary, which is many 10's of uH
(probably 50-100uH for a large coil).  The effects of this stray
inductance can be offset by increasing the coupling of the primary and
secondary coils, probably a very small increase in K would be
necessary.

As to the soldering iron.  Provided you use a decent iron, a single
tip should last you.  My $40 weller station had the same tip for
~2years of frequent use.  Anyway, i know what you meant ;-).

Steve

On 11/5/06, Tesla list <tesla@xxxxxxxxxx> wrote:
>Original poster: "Jim Mora" <jmora@xxxxxxxxxxx>
>
>Hello All,
>
>I have approx 300 CD .15uf caps my goal was to go to 18 strings of 22 (396
>total .12 uf @ 44KV) to handle my three phase DC PS. I may have the
>opportunity to buy 1 or 2 new Condenser Products .1uf 45KV cap which I
>understand take a beating.
>
>Here's my question: I've got to wondering, how much inductance is added to
>the capacitor bank by building an MMC of this size?
>
>Depending on the response here, I may have these for sale. 270 .15uf mostly
>non RohS compliant with bleeders, ceramic beads for temperature standoffs,
>and 400 solder- crimp- barrel connectors for easy, positive assembly. These
>are new in the boxes and bags from RELL.
>
>Opinions wanted. Shall I buy a few new tips for solder iron? Or go to a
>commercial pulse cap(s)
>
>Jim Mora
>
>If I did sell these, I would want min quantity 100 at Rell's cost plus
>shipping. I'll throw in the bleeders and other stuff.
>
>DC Cox will have a large stock of these when he gets to Arizona. So we will
>have no excuses not to build up!
>
>