Re: That secondary harmonic voltage distribution stuff...

Hi Bert,

At 07:25 AM 08/27/1999 -0500, you wrote:
>Tesla List wrote:
>> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>> Hi All,
>>         I have noticed that the secondary voltage distribution graph for 
>my coil's
>> Fo frequency, as I measured last night, follows the equation:
>>         V(dist) = Vmax x dist ^ e
>> where;
>> V(dist) = The voltage along the secondary with the base being zero.
>> Vmax = The maximum voltage (the top voltage in this case).
>> dist = the distance along the coil were the base is 0, the middle is 0.5,
>> and the top is 1.
>> e = the natural log (2.7818...)
>> I don't know if this means anything profound or not, but the match is darn
>> close...
>> Still pondering all this....
>> Cheers,
>>         Terry
>This is an extremely interesting result, since it shows an unexpectedly
>different voltage distribution that the mostly-sinusoidal one would
>expect from a 1/4 wave theory open resonator! In fact, if your
>measurements and approximation formula are close to being correct, fully
>25% of the total output voltage would be confined to the uppermost 10%
>of the winding(!). Previous wisdom/theory assumed that most of the point
>of maximum voltage stress for an unloaded resonator would be confined to
>the bottom portion of the resonator, with a maximum of only about 15% of
>the total voltage stress appearing across the bottom-most 10% of the
>It would be interesting the see if a similar distribution applies to the
>case where the resonator is "pumped" from a primary EM field at Fo, and
>if, indeed, the distribution becomes more linear as top loading is
>added. It may also be that the base-driven CW case may exhibit a
>different voltage distribution than the disruptive case during energy
>transfer to the resonator during ring-up...
>Very interesting results indeed!
>-- Bert --

I posted a nice graph of all this at:


Trace 1 shows the bare coil voltage distribution.

Trace 2 shows the Vm x l ^ e function with a shift of seven which is very
close to the radius of the coil.  There may be something to that.

Trace 3 shows the Voltage distribution of the coil with a terminal.

Trace 4 is the 1/4 wave sine function.  It matches the very end of the Bare
coil case.  The intersection of this trace and trace 2 gives a good clue
how to distribute the voltage on a bare coil ;-)

All this shows why E-Tesla3 had a little problem between terminated and
un-terminated coils.  This also give many hints as to the fix ;-)

I still haven't had time to reconcile this with the lumped theory or write
up a coherent explanation.  I see it in my mind though, just have to write
it out.