Re: [TCML] Secondary to toriod ?

[Ed Phillips <evp@xxxxxxxxxxx>]

stanley miller wrote:

> Hi all,
>
> I am wondering if anyone could explain why a zinc carriage bolt inserted into the center of a plastic cover, glued on top of the secondary, with the bolt head inside covered by a plastic cap would not work or be potentially dangerous.  This would allow the toriod to be completly adjustable, limited only by the size of the bolt.  I have never seen a TC with this sort of setup, it is always with standoffs or pvc piping rigged up in some way or something else.
> Please correct me where my theory is wrong.
>
> -If the secondary cover sits 1.5" to 2" inches above the last winding on the secondary the only thing that could still affect the bolt would be magnetic field which i do not see how it would hurt the bolt or shunt it in anyway.
>
> -Since the toriod would be at the same potential as bolt there would be no fear of arcing to it.
>
> -The bottom inside of secondary would have nothing metal to arc thru from top to bottom.
>
> -since toriod capacitance is dependent on size wouldn't the bolt add a small amount to the overall capacitance of toriod
>
> -I am embarassed to say i have an electrical degree and work in electronic field and am asking such a silly question.  ( but i do not pretend to know anything about tesla coils or high voltage for that matter!)
>
> Thank ya all!
> Stan 
>  
   Since I use an almost identical arrangement with my small TC [3" x 
15" secondary, 24 to 30 inch streamers] here I find no problems at all, 
at least for a coil of this size.  I use a wooden plug in the top of the 
secondary with a long cad plated hex cap screw sticking up through it 
[the bottom end fits into a recess machined into the plug] to mount 
various top loads, all of which have a threaded stud on the bottom.  No 
continuous adjustment but vary the length of the studs as appropriate.  
The top lead of the secondary is fed over the top of the plug.  Usual 
top load is a 3" x 14" toroid with the bottom a couple of inches above 
the end of the secondary winding.

   That being said I have had plenty of problemswith internal arcing 
when I terminated the top and bottom of the secondaries with screws 
mounted through the form from the inside.

Ed

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