RE: Mutual Inductance & K Factor

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

Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi John,

On 21 Mar 2002, at 16:38, Tesla list wrote:

> Original poster: "John H. Couture by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <couturejh-at-mgte-dot-com>
> 
> 
> Bart -
> 
> Thank you for the explanation regarding ETesla6. I should have realized that
> this was a possibility because ETesla6 does this so well. This goes back to
> the time I pointed out on the List that after the TC is built and tested the
> JHCTES Ver 3.3 program can be used to find the true capacitance of the
> toroid when placed on the secondary .
> 
> When the toroid is placed on the secondary the toroid capacitance is reduced
> an indeterminate amount. Etesla6 estimates an operating frequency so the
> toroid capacitance can be estimated very closely before the coil is built.
> The actual value can be found with JHCTES Ver 3.3 or Java9.1 by reducing the
> toroid capacitance value until the program operating frequency agrees with
> the actual test operating frequency.
> 
> The toroid capacitance reduction has been discussed in the past on the List.
> My own limited tests indicated the reduction to be about 15 to 25%. Because
> the only way to find the true toroid capacitance on the secondary is by
> tests all coilers will have to wait until enough tests are made. The
> programs can then be updated to give more accurate outputs.

"Indeterminate amount?" I refuse to believe that a well behaved 
result cannot come from some correct modelling and applied physics.
As for the 15-25% figure, that might be ballpark for a lot of systems 
but as I have found, the actual figure can be almost 100% if the 
terminal has a considerably smaller diameter than the coil. That is 
not to say it is useful or practical to do this but it is an 
illustration of the degree of variation that can be obtained.

Regards,
Malcolm