Barts Flat Coil Dimensions Was: Dimensions of my flat spiral coil

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Original poster: "Barton B. Anderson by way of Terry Fritz <twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>

Hi Dave and All,

I wound a flat coil. It came out "real nice"! Use doublesided carpet tape
(very thin stuff - and
works like flypaper to the windings - and no mess). I took some photo's
I'll put up maybe
tomorrow (35mm camera - not digital). BWT, I simply set the form down on
one of those wooden
thingys which spins food around ot the dinner table, and handwound the coil
using a little tool
to keep press the winding down and against the previous turn. Took a
couple-three hours.

Here are dimensions:

15.0 inch outer diameter
0.375 inch inner diameter
24awg magnet wire (.0201" bare, .0225" total, these were measured)
325 turns (counted)

The wind starts from a brass screw and makes a 0.375" first turn then
simply wound outward from
there. To top off the coil I mounted a 1" brass sphere to make it feel at
home. This coil has no
spacing between turns, is completely flat, no turns overlap, and should be
very similar to
Dave's 13" single turn coil.

My LCR measured 15.0 mH (right on the button). I calc'd 14.8mH. Self
capacitance measured
17.8pF. Notice I'm not reading anything abnormal here. Sorry I couldn't do
a Fr measurement (my
meters at work).

Dave, I'll get to play with my coil later, but as far as your 35mH reading,
I think you need to
recheck. There's no reason this coil is any different from yours. BTW, I
used AMCI to calc the
14.8mH. You may want to use ACMI to calc your coil, then find out why the
measurement isn't
close to it.

Take care,
Bart