# Re: Magnifier Driver coil design

• To: tesla@xxxxxxxxxx
• Subject: Re: Magnifier Driver coil design
• From: "Tesla list" <tesla@xxxxxxxxxx>
• Date: Mon, 18 Apr 2005 21:01:46 -0600
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• Resent-date: Mon, 18 Apr 2005 21:04:07 -0600 (MDT)
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Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Yikes!

6th order does not sound fun (first semester diff eq student, so im
lucky to get through 2nd order stuff).  It looks like i should just do
things experimentally.

I did look at the coupling formula Antonio has supplied (its on his
site as well as at the bottom of this email) and arrived at 2
"conclusions" for a possibly successful design.  First, go for an
overall K (k') of ~.25, where my DRSSTCs seem to really perform.  And
second, use a ratio of about 1:4 for the secondary to tertiary
inductances, which is basically required to get an overall K of .25
with a pri/sec coupling of a reasonable .57.  A ratio of 1:3.5
requires only pri/sec K of .53.  Of course the only problem is
developing too much voltage on the secondary winding, causing corona
loss, or worse, secondary to primary flashover.

I should begin construction in a week or so i think, after im happy
with a design.

Steve

> A difficulty is that a magnifier with a DRSSTC driver is > quite different from a capacitor-discharge magnifier. Design > solutions for this system exist, but closed-form design > formulas would be very complicated, due to the four > frequencies involved (driving frequency and three resonances). > In a first approach, it's possible to design the whole > system as a single DRSSTC system, and then simply decide on > where to split the secondary coil in two, adjusting the > coupling coefficient between the primary and secondary > coils to compensate the moving away of the upper end of > the secondary as the third coil. > Once obtained C1, L1, C2, L2, and k for a regular DRSSTC, > L2 is split into L2' and L3 (L2=L2'+L3), and k is adjusted to > k'=k*sqrt(L2/L2') > A regular DRSSTC design can be designed with the sstcd > program, available at: > http://www.coe.ufrj.br/~acmq/programs > > This ignores the effect of the capacitance to ground at > the transmission line between the top of L2' and the > bottom of L3. To take into account this capacitance, the > four frequencies must be considered. Using the software that > I have developed, this can be done, but is somewhat > complicated. The problem of how to implement a precise > capacitance between the transmission line and ground > appears again, as in the design of a 6th-order capacitor- > discharge magnifier. I can make an example, if there is > interest. > > Antonio Carlos M. de Queiroz > >