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Re: bi-polar (center-fed) TC

The "two distinct secondaries" mentioned in my post are
exactly that: two DISTINCT secondaries. These are
usually both oriented vertically, as shown below:

        Big Streamers between Toroids

O========O                       O========O Toroid
   |  |                             |  |
   |  |                             |  |
   |  |                             |  |
   |  |                             |  |   Secondary
   |  |                             |  |
   |  |                             |  |
   |  |                             |  |
   |  |                             |  |
 pppppppp                         pppppppp Primary
 pppppppp                         pppppppp

Streamers and arcs will establish themselves between
the two toroids. Sometimes this arrangement is
referred to as a "TWIN" coil arrangement. You can
get toroid-to-toroid strikes that are almost
double what you would get from a single coil.

Ed Wingate and others have built very impressive twin
coil systems.

Fr. Tom McGahee

----------
> From: Tesla List <tesla-at-pupman-dot-com>
> To: tesla-at-pupman-dot-com
> Subject: Re: bi-polar (center-fed) TC
> Date: Thursday, May 06, 1999 12:56 AM
> 
> Original Poster: Parpp807-at-aol-dot-com 
> 
> In a message dated 5/2/99 6:31:48 AM US Eastern Standard Time, 
> tesla-at-pupman-dot-com writes:
> 
> <<original Poster: "Thomas McGahee" <tom_mcgahee-at-sigmais-dot-com> 
>  
>  One problem that most experimenters building bipolar center-fed
>  Tesla coils fail to take into consideration is the difficulty of
>  adjusting the coupling. If you simply slide the primary more
>  towards one side, you increase the coupling on one side and 
>  decrease it on the other side.
>  
>  If the experimenter fails to ground the secondary at its center,
>  then approaching either of the ends will cause the voltage on the
>  other end to change drastically. Quite often the circuit will
>  respond by causing sparks to fly between the primary and the 
>  secondary at or near the center.
>  
>  For these reasons it is generally better to make a bipolar
>  Tesla coil that uses two distinct secondaries having the bases
>  both tied to a really good common FR ground. Such a bipolar
>  Tesla coil will have separate primaries for each secondary.
>  The coupling of each can be independently adjusted. 
>  
>  The primaries
>  have to be properly phased so that the tops of the two secondariness
>  are out of phase. You can wind the secondariness in the same direction
>  and the primaries in the same direction, and achieve proper
>  phasing by just phasing the *connection* to the primary. There
>  is NO need to wind any of the coils differently (although that is
>  just as valid a method to achieve proper phasing).
>  
>  Hope this helps.
>  Fr. Tom McGahee 
>  
>   >>
> Tom,
> That is an interesting design for a di-pole TC, it's one that I have not 
> previously seen.
> The center-tapped secondary will always have ends 180 degrees out-of-phase. 
> Same
> for the two primaries which I guess are connected in series. From your 
> experiments,
> just how critical is an accurate determination of the "electrical center 
> line?" This design will also require a mechanical means for the lateral 
> adjustment of the two primary
> windings. 
> 
> Ralph Zekelman
>