# Re: new poster

```In a message dated 1/28/99 3:21:04 AM Mountain Standard Time, tesla-at-pupman-dot-com
writes:

> Hi all.
>  I'm new to this list, been following for a few days - lots of great
>  info. here!
>  I'm a relatively new coiler, with first one under my belt, and next one
>  planned.
>
>  I have two questions:
>  1)Has anyone experimented much with receiving coils? I have a post
>  concerning them but it only recommended making one the same frequency.
>  Isn't it possible to make smaller coils/smaller diameter as long as it's
>  an harmonic of the original coils frequency? It seems I read this in
>  Tesla's patents. Couldn't it potentially be a 3rd or 4th harmonic of
>  the  transmitting frequency? Does it work inversely (1/2,1/4, etc)?

I would think that you would make it the same frequency for best results.
Maybe using a variable cap in place of a topload(or in conjunction with) would
help with tuning.

>  2) Can anyone direct me to a program that includes flat spiral
>  primaries/secondaries? If not, does anyone have the formulas for
>  inductance, capacitance, freq, etc. for the same? All the programs I've
>  tried are for helix spiral secondaries, not flat.
>
Sorry, don't know the capacitance, but the Wheeler equation for a spiral coil
is:

L(uH) = a^2 * N^2 / ( 8*a + 11*w)

where a  =  the average radius, and   w = the difference between the outer and
inner radii.  The measurements are in inches.
Since most people would use the spiral coil as the primary and not the
secondary, the coil's self capacitance is negligible compared to the primary
cap.
Mike

```