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Re: Coily Things
Subject:
Re: Coily Things
Date:
Fri, 21 Mar 1997 21:14:44 -0800
From:
Greg Leyh <lod-at-pacbell-dot-net>
To:
Tesla List <tesla-at-pupman-dot-com>
References:
1
Tesla List wrote:
> I've got some cool equations for you that I worked out a while
> ago which relate f1 & f2 to K. Since f1 = fo/sqrt(1-K) and f2 =
> fo/sqrt(1+K) ... squishing we get fo = sqrt(2/(1/f1^2 + 1/f2^2))
> This relates the 3 frequencies and K. Further squishing gives the
> magical equation: K = 1 - 2 / (1 + (f2^2 / f1^2)).
> This means that you can set up a coil, short the spark gap, connect
> a signal generator to the primary, sweep for the two peak freqs,
> and then DIRECTLY COMPUTE K!! I like this method because it is so
> direct and gives the real effective K value.
>
> <SIDE NOTE>: I have used this same method for some years now. However,
> I have used the approximation of k = df/F (which is in close agreement
> for k's of .2 or less) - MW <END NOTE>.
>
> >- Greg Leyh has been examining some successful coils and has reached
> >the conclusion that a Zs of around 40 - 50 kOhms is a useful value to
> >reach in the secondary. I can't remember whether that was including or
> >minus the terminal but I think it was including.
> >
I should qualify my 40k Ohm preference by stating that it seems like a
good value for Zs, around the 10 kW output operating level. This value
is with the terminal installed, and largely based on empirical evidence.
Bonus Question -- Based on the following information,
----------------------------------------------------------------------
I found (in several volumes) Charles Steinmetz's lectures at the local
used bookstore. In volume I, he gives the power consumed by an arc as
p = c * l * sqrt(i)
(c is an empirical constant, l is length, i is current)
The reasoning is that the current is proportional to the cross-section
of
the arc, while losses due to convection, radiation, etc. are
proportional
to the surface area of the arc.
-Chris Bailey
-------------------------------------------------------------------------
Should the arc impedance increase, decrease, or remain the same as the
output power is increased?
-GL