Re: MMC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "D.C. Cox" <resonance@xxxxxxxxxx>


MMC will blow the doors off any saltwater cap.

I checked my cap chart for you.  A 30 mA xmfr requires a capacitance 
of .008 uF which is 19 pcs of 0.15 uF 2 kV caps in series.  I have a 
bunch of STKs I could sell you for $2/cap.  I would guess total 
shipping at $10.0 for all of these.

Get mom to work and have a pie sale!!!

Dr. Resonance


Hey, I have decided to switch from a saltwater
capacitor to a MMC.  I am planning on getting
either a 15KV 30mA transformer and i dont really
know how to calculate it.  I have tried many
online calulators but i dont know what would be
the best type.... should I go with hundreds of
caps with very small capacitance or a couple with
larger capacitance?  I am on a fairly small
budget ($20-25) for just the caps.  please E-mail
back with some info it would be of immense help, Thanks a lot
Daniel from Canada

> From: "Tesla list" <tesla@xxxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Subject: Re: AC Resistance of wires - was 8 kHz Tesla Coil
> Date: Sun, 02 Oct 2005 22:34:22 -0600
>
> Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
>
> Hi Antonio,
>
> Your formula is the same as the one I originally quoted but reduced 
> somewhat.  ie:
>
> Rac/Rdc = pi*wr^2/ (pi*wr^2 - pi*[wr-sd]^2) = (wr/sd)^2 / (2wr/sd - 1)
>
> The equation for sd that the web site gave seems to predict a little 
> larger sd than what JAVATC calculated.  If this also predicts a 
> little larger sd than what you used, then that would bring the 
> positive errors down some. This approach seems fine to me, but some 
> want something more accurate and doing interpolation on a table 
> lookup is also fine with me.  Once the program adds the routine, we 
> dont have to worry about it anymore :-)))
>
> Gerry R.
>
>
> > Original poster: "Antonio Carlos M. de Queiroz" <acmdq@xxxxxxxxxx>
> >
> > Tesla list wrote:
> >
> > > Original poster: "Gerry  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
> >
> > > The work that Dr Gary Johnson did for AC resistance seems to solve 
> > > the Rac/Rdc problem for round wires (no proximitry effects).
> > >...
> > The following table shows
> > > this for wr/sd up to 8.
> > > wr/sd      Rac/Rdc
> > > ------------------
> > >   1            1.020
> > >   2            1.263
> > >   3            1.763
> > >   4            2.261
> > >   5            2.743
> > >   6            3.221
> > >   7            3.693
> > >   8            4.154
> >
> > A simpler calculation, assuming that all the current is concentrated in
> > a ring with thickness equal to the skin depth and external radius equal
> > to the wire radius, results in:
> > Rac/Rdc = (wr/sd)^2/(2wr/sd-1)
> > The table above becomes:
> > wr/sd    Rac/Rdc  difference
> > 1        1.000    -2.0%
> > 2        1.333    +5.5%
> > 3        1.800    +2.1%
> > 4        2.286    +1.1%
> > 5        2.778    +1.3%
> > 6        3.273    +1.6%
> > 7        3.769    +2.1%
> > 8        4.267    +2.7%
> > The error is negligible in comparison with the more exact formula. So,
> > the basic skin depth formula can be used with round conductors quite
> > well.
> >
> > Antonio Carlos M. de Queiroz