# Re: Tesla calculator frustration.

```Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Bill,

Tesla list wrote:

> Original poster: "Bill Vanyo by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<vanyo-at-echoes-dot-net>
>
> This really should be quite simple, but no...
>
> I just want to calculate where I *should* tap my primary, given the
> following:
> Cap: 0.06uF
> Primary: Inner diameter = 9.75", 1/2" spacing (center to center), 1/4"
> tubing
> Secondary: 1000 turns, 27.625" winding length, 6.625" diameter.
> Topload: 8" chord, 23.5" center to center (capacitance = 34.845?)

I assume your using 24awg wire size when I calc'd this. The toroid
capacitance by itself would
calc to 34.8pF, but when the toroid is set on top of the secondary, the
frequency will increase
possibly by as much as 15% and the effective top capacitance appears to
effectively decrease by
as much as 5 to 40% with a single toroid. This is hard to calc. E-Tesla6 is
the best method at
this time for extrapulating this information. I did however use JavaTC to
look at it: Here's
what I got:

Inductance Ls: 35.92mH
Medhurst Capacitance: 12.4pF
Primary Tap at 7.59 turns

Now, these numbers are just the basics and I did not take into account the
effective change in
Ctop. If I assumed a 12% reduction in toroid capacitance, then Ctop would
be 30.6pF and the
following occurs:

Inductance Ls: 35.92mH
Medhurst Capacitance: 12.4pF
Primary Tap at 7.26 turns

Note, I picked 12% in keeping with Terry's post of 128kHz. However, you
should be the one
running E-Tesla6. The output data should be even more accurate for you as
you wouldn't have to
guess at numbers as we do to fill in the blanks.

JavaTC has been updated (fixed some spacing errors which John Corture
pointed out).
http://www.classictesla-dot-com/java/javatc.html

It should do fine now, but I don't have an input to "reduce" the top
capacitance yet. If you
were to use JavaTC and wanted to drop Ctop by some percent, then simply
reduce the toroid
inputs to attain the desired capacitance. I will be adding another input
into JavaTC soon for %
reduction in effective Ctop one of these days soon (maybe tonight?).

Also, use E-Tesla6. It's a great program and one of kind. If you need any
help using it, just

Take care,
Barton B. Anderson

>
> Previously (with a smaller topload), I managed (or so I thought) to do
> the calculation using JHCTES version 3.2, at
> http://www.miramarcollege-dot-net/faculty/jcouture/tesla/
>
> but now I can't see how I ever did it.  The weird thing here is that
> what I would logically like to specify as input parameters, like primary
> interturn spacing, are output parameters.  I have to try to adjust the
> input parameters to get output parameters that match my existing
> primary.
>
> I've also tried E-Tesla 5 and 6 - got significantly different results,
> and don't quite see how to calculate my tap point anyway.
>
> Are the specs I've listed sufficient for calculating the tap point?
>