RE: [TCML] Interesting Coil Wrap

[Jeff Behary <electrotherapy@xxxxxxxxxxx>]

Jim,
 
If you want to build a bipolar coil, by all means you are correct in what you say below.  Other methods of doing the same thing existed at the expense of a lot of unneccessary work.  It goes back to the turn of the century and a lot of attempts to avoid various patent infringements...  There were also several articles published in the teens/20s using "off the shelf" radio coils to make Tesla Coils...a common arrangement was to take two of these coils mounted back-to-back to make a bipolar coil.  
 
http://www.electrotherapymuseum.com/Library/CurtisHighFrequencyApparatus/pages/Page0107.htm
 
Sometimes two primary coils were used (side by side) to be able to detune one half of the coil for various experiments.  The easiest way to build one though is definately one primary and one secondary coil, primary located in the center, no RF ground...its not to say its the only method, but this method alone is tricky enough at times.  The hardest part is supporting the secondary coil in a way that the coil won't arc to what's supporting it...
 
I did a [crude] repro of a famous bipolar coil that had three terminals (two active, one "dummy") - its an interesting project:
http://www.electrotherapymuseum.com/2007/HighResCoils/StrongOvingtonDisks.htm
http://www.electrotherapymuseum.com/2007/HighResCoils/StrongOvingtonPress.htm
http://www.electrotherapymuseum.com/2007/HighResCoils/StrongOvingtonHiRes.htm
 
One active terminal is a plate, the other a ball.  The dummy has both a plate and a ball.  By adjusting the distance of the plates, it acts as a series-cap with the output and can change the appearance of the sparks between the ball terminals...it adds a lot of interest to the finished coil.  Of course two torroids would look neat too, or any number of other arrangements.  A simple spark discharger always looks nice, espescially if you make them with innerchangeable balls or points or disks to vary the appearance of the discharges...
 
Jeff
> From: wavetuner@xxxxxxxxx> To: tesla@xxxxxxxxxx> Subject: RE: [TCML] Interesting Coil Wrap> Date: Sun, 3 Aug 2008 17:51:40 -0700> CC: > > Hi Jeff,> > Was this a misprint? I thought a bipolar (1/2 wave) coil is usually wound in> the same direction to 2x the usual 3.5-5:1 ratio. A space may be provided at> the mid point to control the coupling. The advantage of this configuration,> if I am not mistaken, is that no RF ground is needed at the midpoint. Please> correct me if I am off on this as I want to build one of these. And I have> read several conflicting responses over the last couple of months.> > Thanks,> Jim Mora> > Condolences go out to the Couture family> > -----Original Message-----> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf> Of Jeff Behary> Sent: Saturday, August 02, 2008 9:30 PM> To: Tesla Coil Mailing List> Subject: RE: [TCML] Interesting Coil Wrap> > > Ryan,> That's an old variation of a bipolar coil. You can have a floating> secondary, two coils wound in the same direction in series with their> midpoints grounded, or you can have two secondaries on the same form wound> in different directions and grounded in the middle. The only thing that> changes is the amount of work involved, and whether there was a common> primary coil or two primary coils back-to-back wound in opposite directions.> > > The idea of CW or CCW coils is a carry over from induction coils that used> pie sections. The first Pancake coils were wound this way too (though two> coils in the same direction would have worked fine too, it just depends how> you innerconnect the primary coils). and when cylindrical coils started to> become marketable this was carryover from that in turn...> > As far as the coil being placed vertically, that's strange. Most of the> time these style coils were mounted horizontally, sparks being drawn from> each end...?> Jeff> > > From: goleafsgo_12@xxxxxxxxxxx> To: tesla@xxxxxxxxxx> Date: Sat, 2 Aug> 2008 12:47:24 -0400> CC: > Subject: [TCML] Interesting Coil Wrap> > > Hey> Everybody, I recently saw a diagram on the internet of a person using a> different coil wrapping style for his secondary. It went something like> this. Imagine a secondary coil winding that starts in the middle, instead of> one end to the other. THis person took their wire, folded the length they> wanted to use in half. From the middle of the secondary, they wrapped half> of the wire length in one direction and towards the bottom. Then, they took> the other half of the wire (the un-used portion as of yet) and wrapped it in> the opposite direction, and towards the top of the coil. My question is:> What would this be used for, and, would it actually work as a> secondary?Ryan_______________________________________________> Tesla mailing> list> Tesla@xxxxxxxxxxxxxx> http://www.pupman.com/mailman/listinfo/tesla> _________________________________________________________________> Your PC, mobile phone, and online services work together like never before.> http://clk.atdmt.com/MRT/go/108587394/direct/01/____________________________> ___________________> Tesla mailing list> Tesla@xxxxxxxxxxxxxx> http://www.pupman.com/mailman/listinfo/tesla> > _______________________________________________> Tesla mailing list> Tesla@xxxxxxxxxxxxxx> http://www.pupman.com/mailman/listinfo/tesla
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