Re: Tesla Coil Blunders

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

Original poster: "Dr. Duncan Cadd by way of Terry Fritz <twftesla-at-uswest-dot-net>" <dunckx-at-freeuk-dot-com>

Hi John!

>To my knowledge no one has ever determined how to find this very
important
>"R" for an operating Tesla coil either by calculation or by tests. TC
>programs are hurting because of this lack of information.If anyone
has any
>comments I would be interested in them.


You can get this from the ringdown time (via logarithmic decrement) of
the isolated secondary (i.e. get the primary out of the loop) as the R
determines the damping.  I can't reproduce all the maths here, but
it's on my page at:

http://home.freeuk-dot-net/dunckx/wireless/sparktx/sparktx.html

The relevant bit starts around half way down the page.  You can
measure the log decrement either by means of an absorption wavemeter
(and I'm sure Ed Phillips would just love to tell you how :-) or by
recording the ringdown on a suitable scope and counting the peaks, a
shortcut to this is also on the above page (if I typed the URL
correctly ;-)

Hope this helps.

Dunckx