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Re: Solid Toroid Beneficial?

Hi Gary,

My program E-Tesla5 at:

http://www.peakpeak.com/~terryf/tesla/misc/E-TESLA5.ZIP

May be of interest to you.  It predicts the fields, charges around a Tesla
coil secondary and determines the fundamental frequency and capacitance.
It makes a file that can be printed in Excel and such of the field
distribution around the coil.  This may help with the electrostatic fields
issues.  However, I doubt it will not help with the input impedance...  It
is a simple viewable BASIC program and has a few notes with it and such.  

More below...


At 07:40 PM 03/16/2000 -0600, you wrote:
>Alan:
>
>Thanks for the note.  The shorted turn effect that has been very steady and
>reproducable for the past two weeks disappeared today.  Might have been a
>high impedance connection, but I can't be sure.  Now I see no effect one way
>or the other.  

Hmmmm.  Don't know what it could have been.  The fact that it disappeared
and perhaps the effect was not real after we thought it was is almost as
intriguing...

>
>I am writing up my research notes, which could easily come to 200 pages.  I
>will make them available for the cost of photocopying and postage.  I could
>have them finished in the next two or three months if I can figure out
>theoretical explanations for some of the observations I am making.  

I will be looking forward to getting a copy too!

>Like
>your observation that raising the toroid improves performance.  I noticed
>that today also, that raising the toroid lowers the input impedance and
>raises the top voltage.  It is not a classic frequency or current
>distribution effect.  I used two toroids, one slightly larger than the
>other.  The larger toroid had the same frequency sitting on the coil as the
>smaller toroid had when 8 inches up.  The current distribution should be the
>same.  But the smaller, raised toroid had 20 percent higher voltage on it.
>If you could think of a reason this might be so, I would appreciate it.

When you raise the small toroid, the top terminal is further out in the
space at the top of the coil.  Thus, it has more capacitance and will draw
greater currents.  Perhaps these greater currents charge the smaller
toroid's capacitance to a higher voltage.  I am not sure about that, but
perhaps...

I have measured the voltage distributions on terminated and unterminated
coils and those are the distributions E-Tesla5 uses and they seem to give
very good results.  The graph is at:

http://www.peakpeak.com/~terryf/tesla/misc/DistGraph.jpg

One immediately notes that the typically expected sine distribution was not
found...

Hope this is some use to you in your efforts.

Cheers,

	Terry


>
>My interest is more in the area of explaining Tesla coil operation than in
>making long sparks.  I have equipment to make a classical coil with
>potential transformers, but may never get around to doing it.
>
>Gary Johnson
>
>At 08:20 PM 3/15/00 -0700, you wrote:
>>Original Poster: "Alan Sharp" <AlanSharp@compuserve.com> 
>>
>>Gary,
>>
>>I read your post with great interest. And your paper on
>>input impedance some time ago.
>>
>>I've also experimented a lot with solid state coils -
>>but I've been discourage by poorly performing circuits -
>>and the number of fets I've blown.
>>
>>My stuff is at.
>>http://ourworld.compuserve.com/homepages/alansharp/
>>
>>I didn't see this shorted turn effect. I noticed that my top
>>toriods were getting hot and so I raised them further away from the coil
>>and performance increased slightly. But I was running at lower powers -
>>under 1kw probably 5kW peak. 14" discharge and very different geometry..
>>
>>http://ourworld.compuserve.com/homepages/alansharp/
>>
>>I have a lot of questions about your circuit and coils. I see with
>>interest that you are direct driving - no output transformer. 
>>
>>Could you be persuaded to post more details and the schematics -  I'ld be
>>delighted to
>>host your material on my site.
>>
>>At present I'm building a conventional coil. It is amusing that the 
>>humble spark gap can still produce much better results than our hitech
>>semiconductor stuff. 
>>
>>Alan Sharp (UK)
>>
>>
>