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



Original poster: "Malcolm Watts by way of Terry Fritz <twftesla-at-qwest-dot-net>" <m.j.watts-at-massey.ac.nz>

Hi Bart, all,
              
On 19 Feb 2002, at 21:07, Tesla list wrote:

> Original poster: "Barton B. Anderson by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <tesla123-at-pacbell-dot-net>
> 
> Hi Dave -
> 
> Tesla list wrote:
> 
> > Original poster: "David Thomson by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <dave-at-volantis-dot-org>
> >
> > Hi Bart,
> >
> > The 224 is the number of wires one would count from the center of the coil
> > along the radius.  But each wire only makes 74.6 turns.  3 wires times 74.6
> > turns yields the number of wire counts along the radius.
> 
> Ok, that clears that up. 74.6 turns should then be used.
> 
> > Could it be that three wires tightly coupled and wound in parallel act as
> > one single continuous wire?.
> 
> I don't think so (but not sure). The meter, I don't trust the reading. Your
> single turn 13" coil
> has a higher inductance and yet your getting an extremely high reading.
> Your 3-wire coil has a
> lower inductance and may be enough to throw off the reading way out in
> no-mans land. Since your
> meter appears ok with capacitive readings, how about checking the resonant
> frequency of the coil
> (by itself) and back calculating inductance?

Sounds like it might be time to start applying Medhurst etc. to flat 
spirals. I'll dig into my Radiotron Designer's Handbook to see what 
formulae for Cself exist.

Regards,
Malcolm