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RE: SSTC design procedure



Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz> 

Hi Steve,

On 14 May 2004, at 13:33, Tesla list wrote:

 > Original poster: "Steven Ward" <srward16-at-hotmail-dot-com>
 >
 > Malcolm,  comments within:
 >
 >
 > >From: "Tesla list" <tesla-at-pupman-dot-com>
 > >To: tesla-at-pupman-dot-com
 > >Subject: SSTC design procedure
 > >Date: Thu, 13 May 2004 16:25:01 -0600
 > >
 > >Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
 > >
 > >Dear all,
 > >           I would be interested to learn the following from the SSTC
 > >community on the list:
 > >
 > >(1) what is your design procedure for the actual pri-sec setup (i.e.
 > >do you just build something and live with what you end up with, or do
 > >you choose a particular Lp for such-and-such a reason, Ls for some
 > >particular reason, and so on....)?  I'd be interested to know which
 > >approach you take and if the latter, the general procedure you use.
 >
 > Well, a good portion of my SSTC design work has been based off of
 > other's work as well as my own experimentation.  Usually i go for the
 > highest coupling and lowest Lp possible.  This of course depends on
 > voltage stand off as well at the switching devices capabilities.  Im
 > also assuming you are referring to a "normal" SSTC that runs more
 > "CW"-like and not the newer pulsed SSTCs.  Anyway, you want to
 > maximize K and minimize L in most cases. Higher K results in lesser
 > magnetizing current being out of phase (which will produce heat and
 > not so much sparks).

Why the lowest Lp. Is this for any SSTC or just an offline one?
 >
 >
 > >(2) What is the general balance between "calculate" and "pray" in
 > >your final results?
 >
 > Honestly, quite a bit comes from just experimenting with lashups of
 > the design.  Its very critical to get the electronics right, but the
 > coils themselves are more experimental.  There are so few SSTCs out
 > there that no one has really given any general guidlines to go along.
 > Personally i go with the lowest Fres for acceptable size, but i also
 > take into account wire resistances and Q.

Any comments on Ls/Cs or the absolute values of either?

 > >Needless to say, I have reasons for asking and it has nothing to do
 > >with design piracy ;)  There was another question I wanted to ask as
 > >well but it's slipped from mind for the time being. I may post a
 > >further query later.
 >
 > So i assume you are planning to build a SSTC?  If you have any
 > questions im always willing to help.

I will get to it when I have got rid of a number of obligations,
hopefully by the end of the year. But I'm looking at going an extra
mile. The conventional SG design which I produced and then used as
the basis for a magazine article was a deliberately designed one-off
and while not perfect in all respects (being limited mainly by an
available transformer), was straight out of the box with very little
experimentation. Plug and play in actuality. The design procedure was
the result of a decade or so's accumulated knowledge and thinking and
the coil was literally designed in 15 minutes on the back of an
envelope over a cup of coffee.

     As someone who designs electronic goodies for a hobby and
sometimes in my job, the onus I apply to myself is that unless I can
justify every component and its value in a design, the design has not
been done properly and could well be improved upon.

Thanks for helping.
Malcolm