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Re: Frequency vs temperature

Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>

Hi Jim,

At 06:52 AM 5/3/2002 -0700, you wrote:
>Is there a data file (having not looked this morning at your raw data) that
>has just F,R, and T as a function of time? (i.e. not the raw scope traces)
>Do you have a ballpark estimate for the mass of the top load (to estimate
>thermal inertia) and likewise for the secondary.. (Or, I can estimate from
>the size of the PVC+ mass of windings?)
>Then, I can see if there is a suitable correlation between variations in F
>and temperature of various components (I expect the top load to have a
>shorter time constant than the secondary...it's aluminum and has a much
>larger surface area to mass ratio, so it will track air temperature).

The data you seek should be in the file at:


The top load is one of John Freau's 4 x 13 torroids.  I have the tape on
it's construction...  0.040" thick Al T6061  Two disks that are 7.5 inch
radius.  I'll take 0.005 inch off the thickness for sanding and such.

pi x r^2 = 176.7 square inches or 353.4 for two sheets.

353.4 x 0.035 = 12.37 cubic inches of 6061 Al

that is 2.0271e-4 m^2

or about 0.5477 kg (1.2 pounds) of aluminum.  So it takes 494 joules to
raise the temperature 1 degree C.  My book has the expansion at 22.5e-6 /
degreeC but that may differ some for 6061 alloy.

The secondary is a 27 inch long 4.25 inch diameter 1/8 inch thick PVC pipe.
 It has close to 1175 turns of #24 wire on it.  There is no coating on it.
It is just like my other coil but it is taped so I can run it better with
the solid state coil setup that has a limited frequency range.

E-tesla6 will not see a tiny ~0.005 inch variation since it puts the
dimensions on a big grid with a little point rounding going on.  A tiny
dimensional change would easily get lost in the coarse grid.