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Re: [TCML] Modeling a compact ribbon primary



Thanks to Paul for the fantastic write up!  I am still reading on it!

The good news in my primary strap has arrived, after taking in Pauls info, couple of days probably! the next task is to space up the primary. I am not sure what I am going to use as a spacer for the primary yet, probably end up being a couple of cornflakes boxes! Once built, I can take readings if they are in the limits of my poor test gear!

Chris




----- Original Message ----- From: "bartb" <bartb@xxxxxxxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Sunday, August 03, 2008 9:20 PM
Subject: Re: [TCML] Modeling a compact ribbon primary


Hi Chris, All,

This is an excellent writeup and I hope all read and put their minds into gear to comprehend what is discussed. The basic issues discussed go across the entire spectrum of coil physics. Near the lower portion of the writeup are links to TSSP documentation. Take your time and read through those as well. The physics accompanied with this ribbon primary configuration applies to all coil geometry across the board. Geometry certainly changes the situation, but in all cases, these basic properties must be comprehended and studied for a best estimation of the coil. This writeup may help those that use JAVATC or FANTC understand better Les and Ces units (what they mean and why they are distinguished).

All my best,
Bart

Paul Nicholson wrote:
Hi All,

Chris Swinson recently wrote:

> my primary will be 4 turns of 2" wide strap separated about
> 1mm apart.. the dia is about 22"

and asked whether turn-to-turn C needs to be accounted for.

My stock reply was 'no', because the overall effect of inter-
turn C has always been negligible in the coils we're used to
looking at.

But this is rather an extreme case and closer inspection reveals
that it does have a dramatic effect, at least on the bare coil
itself, although once the coil is connected to a primary cap
of say 3nF, the effect of inter-turn C is much less.

The inter-turn C, it turns out, alters the coil's effective
inductance, rather dramatically for the bare coil, and is
very significant.

I began a note to explain all this, but it got a bit long,
so I turned it into a web page.  In the end it turned into
something of an essay which delves into the concepts of self
capacitance and self inductance and explains how they're defined
and modelled.  I try to show how the coil's effective inductance
is altered by the internal capacitance of the coil and use a
spice model for illustration.  This effect is something which
occurs in all our coils but is particularly clearly demonstrated
in this extreme primary.

 http://abelian.org/tcml-notes/080728.html

Hopefully it will be an interesting read and will shed some
light on the distributed self reactances of coils in general.
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