Re: bi-polar (center-fed) TC

To: tesla-at-pupman-dot-com
Subject: Re: bi-polar (center-fed) TC
From: Parpp807-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)
Date: Wed, 05 May 1999 22:56:29 -0600
Approved: twftesla-at-uswest-dot-net
Delivered-To: fixup-tesla-at-pupman-dot-com-at-fixme

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