Noah,
Toroids that are larger produce longer sparks, but after you get to a
certain point, breakout is impossible. The simplest formula for
determining that size is this, C in pF=SQRT (input power in watts). I
usually size my toroids for 0.9* this value. Another quick and dirty
formula that is handy is toroid C in pF is roughly equal to toroid overall
diameter in inches. Obviously these formulas were determined empirically,
the first by John Freu if memory serves, and I figured out the second one
by playing with Java TC (other may have noticed it before then).
Scott Bogard.
On Mon, Jul 28, 2014 at 11:21 AM, mddeming--- via Tesla <tesla@xxxxxxxxxx>
wrote:
> Hi Noah,
>
>
> Using simple formulas that are usually within 5%:
>
>
> Once you have the Primary capacitance and secondary coil size, then the
> maximum primary inductance determines the maximum secondary capacitance,
> since at resonance,LpriCpri=LsecCsec.
>
>
> Now Csec is the sum of the internal capacitance of the secondary (Cint)
> plus the capacitance of the toroid(Ctor). This means that the largest
> toroid capacitance you can use is
>
>
> Ctor=LpCp/Ls - Cint
>
>
> There are many combinations of toroid major and minor diameters that will
> give the same Ctor:
>
>
> For a quick calculation:
>
>
> Ctor=1.4(1.2781-D/d)*sqrt[pi*d(D-d)} with C in pF d & D in inches.
>
>
> For exact, detailed calculations see:
> http://www.coe.ufrj.br/~acmq/tesla/capcalc.pdf
>
> With no topload, Csec=cCint which yields a minimum Lpri of LsecCint /
> Cpri.
>
>
> 1) For tuning purposes it is a good idea to have a slightly greater range
> on the primary coil than the calculated Lmax & Lmin values imply.
> Also, some people claim that better results are obtained when Ctor>=Cint
> which would further restrict the minimum size of toroid.
>
>
> Hope this helps,
>
>
> Matt D
>
>
>
> -----Original Message-----
> From: noahbdanglin <noahbdanglin@xxxxxxxxx>
> To: tesla <tesla@xxxxxxxxxx>
> Sent: Sun, Jul 27, 2014 8:41 pm
> Subject: [TCML] Choosing the right toroid
>
>
> Hello,
> I have been doing a lot of research concerning what size toroid is best
> for my
> system. One thing I cannot find out however is how toroid size relates to
> the
> rest of the system. Yes, larger toroids have more capacitance but how do I
> know
> how much capacitance my system would best operate with? I am asking for
> calculations for and basic theory of toroids compared to the rest of the
> Tesla
> coil. Any help would be greatly appreciated.
> Thanks.
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