Re: Four Layer Coil

Subject:  Re: Four Layer Coil
  Date:   Mon, 16 Jun 1997 00:39:14 +0000
  From:   "Bert Pool" <bertpool-at-flash-dot-net>
    To:   Tesla List <tesla-at-pupman-dot-com>

> Date:          Sun, 15 Jun 1997 09:43:05 -0500
> To:            tesla-at-poodle.pupman-dot-com
> Subject:       Four Layer Coil
> From:          Tesla List <tesla-at-pupman-dot-com>

> Subject:  RE: Latest magnifier results - wire shape
>   Date:   Sun, 15 Jun 1997 07:33:38 +0500
>   From:   "Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
>     To:   Tesla List <tesla-at-pupman-dot-com>
> On Fri, 13 Jun 1997 22:40:13 +0000 Bert Pool
> <bertpool-at-flash-dot-net> wrote;
> > I covered this in earlier posts, but here it is again.
> > 
> > We wound our first layer exactly as always.  The second layer over 
> > over the first - same direction.  You'll find that it is very 
> > important that there be NO gaps in the underlying layer or you will 
> > have problems with the next layer.  We did a total of four layers.  
> > Next, we soldered all four wires together.  In effect, the four coils 
> > are in parallel.
> It would see to me that placing the layers in parallel you would be 
> decreasing the inductance, ie.
>  Total I = 1 / (1/Ifirstlayer) + (1/Isecondlayer)...+(1/Inthlayer)
> Are you saying that even though it reduces the inductance it is still 
> a gain over using the equivelent larger gauge wire?

Alfred, it was 26 years ago that I had learned this equation you 
posted.  Fortunately, I forgot it about 25 years ago, so it did 
not prevent me from winding and testing multiple layer coils!  

I have to report that you are wrong when you say that the second 
layer will reduced the inductance.  I'm not saying this because a 
text book led me to believe the inductance would be lower, and 
I'm not saying that I =think= the inductance might be lower, I =know= 
it is not lower because I've actually built several of these coils 
and carefully measured the inductance as I added each layer, and 
winding multiple layers does NOT reduce inductance one iota.  To 
prove it to yourself, please wind a coil and measure the inductance.  
Then wind a second layer and connect it in parallel with the first 
and  re-measure the inductance. The inductance will =not= have 
changed appreciably from the first reading. K is approaching unity in 
such a configuration.  But you absolutely will have cut the d.c. 
resistance in half and the surface area of the conductors will have 
doubled as well, and both factors will significantly reduce rf losses 
in the coil.

Winding successful coils in Ft. Worth, Texas, 'cause I don't know no 

Bert Pool