Re: Twin Coil question . . .Primary Connections

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

Original poster: "Kurt Schraner by way of Terry Fritz <teslalist-at-qwest-dot-net>" <k.schraner-at-datacomm.ch>

Hi Steve, Dan,

my comment at the end...

Tesla list schrieb:
>Original poster: "Steve Conner by way of Terry Fritz 
><teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>
>
>Subject: RE: Twin Coil question . . .Primary Connections
>
>  > Original poster: "Mccauley, Daniel H by way of Terry Fritz
><teslalist-at-qwest-dot-net>" <daniel.h.mccauley-at-lmco-dot-com>
>  >
>  >
>  >
>  > So no real benefit between running the primaries in series, or running
>them
>  > in parallel???
>  >
>  > Dan
>Running them in series will give you 4 times the surge impedance hence the
>system will tune with one quarter the tank capacitance (and require twice
>the supply voltage) compared to a parallel connection. So one or the other
>might be preferable depending on the voltage/amperage of your power supply,
>resonant frequency, and type of caps you have available.
>Steve C.
Steve, your argument is only of practical value, if the cap-value is NOT 
based on the feeding PSU (i.e. NST), but changed and matched to the 
resulting primary inductance. For a fixed primary cap value, the resulting 
inductance, - beeing it composed by a parallel or a serial connection of 2 
inductances -, need just to be the same value of resonant L, dictated by 
the secondary's conditions.

However I prefer serial connection of the primaries, as mentioned already 
in a posting of April 6th, Subject:Twin Tesla coils. There was no 
confirmation by R.Scott Coppersmith, if his Twin primaries were indeed 
connected in parallel, but before he reported:

"The tuning of my twins was a pain in the -at-#$%!!"

...which, I believe, might be, because it can be more difficult to 
distribute equal currets to the 2 primaries than equal voltage (in a 
resonant situation). Obviously, the proximity of more or less conducting 
stuff, near the twin, easily can inbalance the symmetry of the tuning. The 
energy may then again be distributed evenly, by tapping the 2 primaries 
somewhat differently. See also Bill Wysocks detailed description of his big 
twin Model 12 coil:

http://www.ttr-dot-com/Model12_ITS_article.htm

I also recommend winding all primary and secondary coils in the same 
direction and in principle connecting both tapped ends and both inner turn 
ends of the primaries, as already posted by Terry Oxandale on April 
4th,2003, Subject:Twin Tesla coils  -  of course, somewhere introducing the 
cap and gap.

Kurt