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Re: Question on Ceiling Height/Material

Original poster: "Barton B. Anderson" <bartb@xxxxxxxxxxxxxxxx>

Hi Jim,

Tesla list wrote:

Original poster: "James Zimmerschied" <zimtesla@xxxxxxx>

Hello List Members,
I recently noticed that the ceiling height and material can make a significant difference in a coil's secondary frequency.
Yes, absolutely. When I operate my 8.5" coil which uses a 9" x 30" Lundgren toroid in the garage, I have to retune it when I take it outside. On your particular solid state coil, I'm not sure there. Seems to me the coil would be in the smaller class of coils and would be less prone to moving so far out of tune due to ceiling material. I wonder, did you take it back home and try again with the same results?

In playing with parameters in JAVATC, I see a noticeable change between an 8 ft ceiling and a 12 foot ceiling. I don't see anything in the program that inputs the material type for the ceiling. I would think a non-conductor like gypsum wallboard would have less effect than a flat steel roof. Maybe Bart could shed some light here.

No, there is no material input and I don't think there should be. These system components are fed into Geotc and their external capacitance effects are included into the output numbers. Trying to decipher material properties might be overwhelming (think of wood houses on a dry day vs. a really rainy day). I believe Geotc would see the surrounding objects as conductive objects. For my particular garage (which is all wood), I really don't need to change the surrounding inputs, but I'm sure there are cases such as yours.

I would suggest measuring Fres and changing surrounding inputs until Fres(calc) = Fres(meas). You would then have the surrounding inputs for your particular material, and those same inputs should work for all the coils you intend to build and run in that area.

Take care,