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    Tesla Coil Ring           Concentric Spheres (CS) & Adjustable Support

Updated July 26, 2004        CS formerly known as a 'sphere-in-sphere' - sizes are at the bottom of this page

These photos and text describe the mounting of the CS onto a coil form.  A sphere half is called a 'shell'.

Brief recap:  While discussing two obscure Wardenclyffe magnifier designs with Charles Yost of the Electric Spacecraft Journal (highly recommended), he suggested I build a CS top-load. Tesla's diagrams illustrate this and can be viewed by clicking -> Magnifier Diagrams.  In both, by removing the upper sphere (used to rectify the output), there remains a sphere inside the large top-load, a sort of concentric sphere.  Using an 8" cu sphere on my twin parallel magnifier I measured 24" discharges and after swapping that out for a 5" in 8" CS I measured 37" discharges.  The electrical connection was now to the 5" sphere and none of the machine's settings were changed.  I don't fully understand the mechanism behind this yet but more experimentation is in the works, especially in the sphere spacing.

                               

1                                 2                                3                                4                               5

Installing a Concentric Sphere

First, secure the included support rod to the top of your coil, at the bottom of this page are photos of the adjustable assembly I use.

Solder a copper tab onto the end of your resonator wire, flatten 1/2" of the stripped mag wire before soldering to tab that is pre-drilled with a hole large enough for the nylon bolt.  Feed the tab and attached wire through the large hole in the outer shell and carefully lower it onto the top of the resonator form.  Place the copper tab on the top of the acrylic support rod, screw in the nylon bolt and bend the copper tab down then unscrew the nylon bolt.  You want the resonator lead to be very close and parallel to the support rod as seen in photos 2, 5 and 10.

Take the smaller shell, with the small hole in its center, and place it over the threaded hole in the support rod, be sure the copper tab is between them, then screw these together with the nylon bolt.  Your assembly will now look like photo 1 and photo 2.

Now mate the shell (with the teflon support) with its bottom half and press together.  Your assembly will now look like photo 3.

Photo 4 - Carefully balance the remaining large shell on the teflon support.

Raise the lower shell up and carefully engage with its top half, raising the top half 1/2" or so above the teflon support and press them together.  When both shells are fully engaged, lower it so that the outer sphere assembly rests upon the teflon support.  One note of caution, do not press the shells together too tightly as you will need to separate them to remove the top-load but you don't want it so loose that it falls apart.  Separating the outer sphere may be a slow and deliberate process in order not to damage the shells and aluminum spheres may separate easier than copper.  Finally, looking from the bottom at the large hole that the support rod goes through, carefully position the outer sphere so that the spacing around the acrylic rod in equal.  Photos 5 and 10 show that final positioning.  You're now ready to fire.  The only remaining adjustment is to find an optimum sphere height.

Adjustable Top-Load Support Structure

                                     

6                                     7                                     8                                      9

I use this adjustable support for all of my smaller top-loads:  Sphere, CS and toroid.  For top-loads over six pounds or so you need a redesigned locking ring.  The above photos, along with this commentary, should allow you to build what you see in photo 6.  If something is unclear, email me for a clarification.  Alternatively, I can provide them for a small charge.  If your form is out-of-round the three discs and form will require alignment marks to properly trim and fit them.

Photo 6 - the adjustable assembly.  The disc at the left in that photo is actually two discs joined with double sided tape (you could use acrylic cement).  The larger one will have the same or a bit larger o.d. as your form.  The smaller disc needs to be a tight friction fit into your form so that it will 'snap' into place and stay there.  The disc on the right side of photo 6 slides into your form and needs to travel freely.  If that disc is cut too small the top-load may lean to one side, not a good look.

Photos 7 and 8 illustrate a range of travel.  Photo 9 shows the CS installed on a 6" form and ready to fire.  The form in photos 7 & 8 has an o.d. of  5".  This support will work with any coil form with each diameter requiring its own appropriately sized set of acrylic discs.

Double Concentric Spheres - Available Sizes

Triple CS - Under Evaluation

 

Here's a beautiful example of a seamless cu toroid manufactured by John Freau.

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