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Re: Frequency vs temperature
Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>
I was thinking about using a first order approximation like C is
proportional to size (for small changes) and similar for a Wheeler type
equation.. That is.. N will stay the same but length and diameter will
change as function of temperature.
Tesla list wrote:
> 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.