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Re: Toroid Design Features


From: 	Bert Hickman[SMTP:bert.hickman-at-aquila-dot-com]
Reply To: 	bert.hickman-at-aquila-dot-com
Sent: 	Sunday, November 09, 1997 5:31 PM
To: 	Tesla List
Subject: 	Re: Toroid Design Features

Tesla List wrote:
> 
> From:   Chuck Curran[SMTP:ccurran-at-execpc-dot-com]
> Sent:   Saturday, November 08, 1997 12:09 PM
> To:     tesla-at-pupman-dot-com
> Subject:        Toroid Design Features
> 
> Hello All:
> 
> I'm in the process of deciding on how to prioritize coil improvements for
> the next few winter months.  Near the top of the list is the toroid.  I am
> going to get pricing for a spun aluminum toroid and that is where a question
> pop's up right away.
> 
> Many of us have made a toroid using a similar set of design features.
> Specifically, a flat center disk surrounded by the "Donut".  The large
> radius Donut clearly prevents the premature spark breakout, but results in a
> shape that may increase the cost of a spun aluminum item.  Here's the real
> question.  When I draw up a design to take to a local spinning supplier, I
> would like to have as much flexibility as possible to control the cost.  I
> see a toroid that would be, let's say 10" thick with a 5" edge radius as
> being just as effective as one with the 10" diameter outer donut coupled to
> a thin center disk.  I hope the cost would also be lower.  The capacitance
> should be almost identical too.  Have I missed something here, or would the
> thick top hat be just as effective?  We have many local metal spinning job
> shops and any flexibility in the design would sure be a benefit.  Thanks in
> advance for any comments.
> 
> Chuck Curran

Chuck,

The outer surface doesn't need to even be a complete circular
cross-section. As long as the SMALLEST radius of curvature is say 5" or
greater, it will work properly with the same breakout voltage
characteristics and the self-C will be about the same. Since the top of
the secondary winding itself creates a significant degree of e-field
"shading", the following cross-sectional shapes will all be roughly as
effective as long as you don't elevate the toroid very much above the
top of the winding.

          ..............................
        .                                .
       .                                  .
       .                                  .  (A)
        .                                .  
          ..............................
     

          .   .                    .   .
        .       .                .       .
       .         .              .         .
       .         .--------------.         .  (B)
        .       .                .       .  
          .   .                    .   .


          .   ......................   .
        .                                .
       .                                  .
       .   {open area)                    . (C)
        .                                .  
          .   .                    .   .


Safe coilin' to you!

-- Bert --