Re: streamer impedance matching, was Re: Fwd: Re: Calculating streamer breakout of top-loads

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi All,

I should point out that the 220K + 1pF per foot of streamer capacitance is 
sort of an "average" value.  The 220K seems to be fairly stable, but 
certainly the capacitance varies a lot during streamer formation.  Before 
the streamer starts, the impedances are no doubt very high.  Then as the 
hot streamer forms and lengthens, the impedance drops.  In general, it 
seems like streamers are actually a very light load on the normally much 
lower output Z coils systems.  Also, note the much lower values for my CW coil:

http://hot-streamer-dot-com/TeslaCoils/MyCoils/CWCoil/CWImpedance.txt


I just got my new tube coil running again after blowing the tubes (got nice 
new  Svetlana's now* ;-))  But as I was blowing it up, I noted that the no 
load to streamer load frequency was only like 350kHz vs. 348kHz indicating 
a very light streamer load.  I have not studied the new toob coil much at 
all, but the streamer load seems trivial to it.

I really like the toob coil!!  I bought that one of E-bay a few weeks back 
since I am to lazy to make one from scratch.  Easier than "me" trying to 
figure it all and make one 0:-))

*someday, we will have to have a thread about tube quality...  1988 vintage 
Cetron 811A's Literally fell apart since the glue used to hold them 
together did not stick to the glass.  One arced in the base area where the 
pin connections are...  The 1996 vintage Svetlana's look and work perfectly 
;-))

Cheers,

         Terry


At 10:59 AM 9/15/2003 -0500, you wrote:
>Hi all,
>
>I have a few problems/questions with this argument, interspersed throughout.
>
> > Original poster: "Malcolm Watts" <m.j.watts-at-massey.ac.nz>
> >
> > On 13 Sep 2003, at 10:33, Tesla list wrote:
> >
> >  > Original poster: "Gerry Reynolds" <gerryreynolds-at-earthlink-dot-net>
> >  >
> >  > I wondered this myself,  If you have a source with say a fixed source
> >  > impedance and you vary the load impedance, then the maximum power
>transfer
> >  > is with the Zload = Zs.
>
>First, with complex load and source impedances, the max power transfer is
>Zload = Zs*, that is the complex conjugate.
>
>However, if the load impedance is fixed and the
> >  > source impedance is varied, then the maximum power transfered is with
>Zs = 0
> >  > to get maximum voltage on the load.
>
>Zs = 0 for max power, and we're relatively close to that for a TC.  First,
>the voltage is high, and the DCR low enough to allow for 100+ amps.  Second,
>we're purposely running at resonance, or close to it - i.e. Xl = -Xc.
>Sometimes systems are out of tune a bit, it's not easy (possible) to get
>*perfect* tuning.  Also, many people detune to account for streamer
>loading - the added capacitance of the from the streamers.  This is just
>taking the extra capacitance into account to meet the resonance condition,
>Xl = -Xc, more C, need a lower frequency to increase Xc, and decrease Xl.
>
> > Suppose the idea is a goer. The challenge is then on to build a
> > secondary whose output impedance remains a conjugate of 220k - jnwC
> > where n is expected spark distance in feet and C is the 1pF. At least
> > I'd consider it a challenge. Just meeting the 220k requirement would
> > be a nightmare.
>
>
>Well, to match the 220k part would be pretty easy, just throw a resistor on
>top of the coil, or bottom, (a HV rateed one) :-)  The resistance wouldn't
>be distributed like it is from the wire resistance, but you don't need it to
>be.  It would also waste a WHOLE lot of energy, and as was already pointed
>out, with a fixed load impedance, max power into the load occurs when Zs = 0
>.  We can't get that, but we can get as low as possible.  Low R, and zero
>complex impedance.  But changing the inductance is where you'll mess things
>up.  The tuning of the coil will be thrown off, and you'd have to retune to
>get the same output.  But by retuning, you've just changed the frequency so
>once again, Xl = -Xc.  Guess we need to add another inductor :-)  You can
>see where this is going . . . a never ending cycle of more inductance and
>tuning.  Just tuning for the added streamers will cause the complex
>impedance to be minimized - that's the whole idea of resonance.
>
>Feel free to send any comments/questions/flames.  As a disclaimer, this is
>just me view of what's going on, and may be a little, or more than a little
>off :-)
>
>Sean Taylor