Breakout

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Luke" <Bluu-at-cox-dot-net> 

Maybe someone could tell me if I am barking up the wrong tree or if I have 
an idea worth thinking about.
The question of the specs is not oriented to find the right size toroid for 
the coil but to find a maximum inductance value that would be needed for 
the coil no matter what kind of top load values you threw at it. This would 
avoid the need to add primary turns if you went too big on the toroid.  No 
matter what you did with top load size you would always have enough primary 
to tune to it so it would be less likely the primary would need to be 
re-designed.

This was my idea.

Take the formula for the output of a TC system:
Cp * 0.5 * Vp^2 = Cs * 0.5 * Vs^2

Re-arrange it to solve for Vs and representing Cs as Ct + Cself:
Vs = sqrt(Cp*Vp^2)/(Cself+Ct)

Then substitute the formula for the capacitance of a toroid for Ct:

Toroid capacitance:  C in farads  D1 major dia.  D2 minor dia.
C = (1.4 * (1.2781 -(D2/D1))* sqrt(pi*D2*(D1-D2))/1,000,000,000,000

Capacitance formula substituted in:
Vs = sqrt((Cp*Vp^2)/Cself + (1.4 * (1.2781 -(D2/D1))* 
sqrt(pi*D2*(D1-D2))/1,000,000,000,000)

I put this formula in a spreadsheet so I could plug in the values for a 
coil and then vary the values of D1 and D2 to get different theoretical max 
outputs for the system.  Yes I know this voltage will not be realistic.  I 
thought the max amount of energy the capacitor could deliver the the system 
in any one gap firing would be if the cap were charged to the peak voltage 
of the power supply.  Even though this does not usually occur it is what I 
thought would be the maximum amount of energy the cap COULD deliver to the 
system.  This is not for use with systems operating with a MC at a resonant 
value (resonant rise) and it is for use where a safety gap has limited the 
peak voltage to the cap to that of the peak voltage of the supply transformer.

Any way
One could then plug in various values of D1 and D2 to get various values 
for V2.

The same values for D1 and D2 would then be input into the Inca program to 
get a breakdown voltage for the toroid.

I have looked at various coil specs for those able to break out and those 
not able to break out (only two of the later).  When dividing V2 by 
Vbreakout I get a percentage.  The lowest percentage I have found is for a 
coil operating at is 58%.  Note if you use a larger toroid on the same 
system you will get larger break out voltage and a lower Vs therefore a 
lower percentage.

I know the break out voltage will not be accurate because of the surface of 
the toroid etc.

But was hoping to look at a lot of coil specs and see what the lowest 
percentage was that I could find.

Then using a percentage say around 45% you could determine what might be 
the largest capacitance your system might EVER see as a topload.  Then use 
that value and apply it with the other coils specs to determine the max 
amount of inductance you would need for your primary to tune to that top load.

This would avoid having to make a larger primary in the event you tried a 
larger top load.  Yes I know this may result in the primary being larger 
than actually needed.

I know this might be a little unclear and I probably sound like a nut case.
But if any one sees where I am going with this I would appreciate any comments.


Luke Galyan
Bluu-at-cox-dot-net