RE: 3 Coil System Was: A photographic tutorial of PancakeCoilwinding...with movies...(fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 24 Jun 2007 12:16:20 -0500
From: David Thomson <dwt@xxxxxxxxxxxx>
To: 'Tesla list' <tesla@xxxxxxxxxx>
Subject: RE: 3 Coil System      Was: A photographic tutorial of
    PancakeCoilwinding...with movies...(fwd)

Hi Bart,

> Flat Coil = 13.625" outer diameter, 24 awg, 2" inner 
> diameter, 252 turns, 

Did you count the number of turns, or did you calculate them?  If your coil
is tight wound, there should be about 283 turns at 98% winding efficiency.
But this is irrelevant.

I just tested a 13" outer diameter, .25" inner diameter coil at one inch
from the center and there is a 10 degree to 15 degree angle of flux there.  

I just tested an 11" outer diameter, 4" inner diameter coil at one inch from
the center and it too has the same angle of flux.

So at 1" from the center of the coil, you do have a weak inductive coupling.


> I then removed the solenoid coil and placed it 1 meter away 
> from the flat coil. I kept it hooked up electrically the 
> same. I measured 0 volts across the solenoid with the same 
> current flow. 

At what distance does the inductive coupling disappear?  I would expect the
inductive coupling would disappear just a few inches above the spiral plane.
My solenoid coil was mounted about 2.5" above the flat spiral plane,
specifically to minimize the inductive coupling.  Although, I didn't
actually check to see that inductive coupling was completely eliminated.  

I just now tested the 25.25" outer diameter, .25" inner diameter flat spiral
coil.  Due to its size, the angle of flux at .7" from the center is
practically zero.  Add to this the fact the solenoid was raised 2.5" off the
plane of the flat spiral and there is practically no inductive coupling
between them.  Unfortunately, I no longer have the tall solenoid coil used
in the experiment to measure the exact coupling.  But I will keep this in
mind when I build my next coil.

> The definition of "inductive coupling" = "the transfer of 
> energy from one circuit component to another through their 
> shared magnetic field (mutual inductance)". Is your 
> definition of inductive coupling something other than this?

We share the same definition of inductive coupling.  We just aren't putting
our coils in the same configurations when taking measurements.

Dave