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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