Re: Four Layer Coil

Subject:   Re: Four Layer Coil
  Date:    Mon, 16 Jun 1997 13:16:35 +0500
  From:   "Alfred A. Skrocki" <alfred.skrocki-at-cybernetworking-dot-com>
    To:   Tesla List <tesla-at-pupman-dot-com>

On Mon, 16 Jun 1997 00:39:14 +0000 Bert Pool
<bertpool-at-flash-dot-net> wrote;

> > 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 
> better,

Bert, I realized what I missed about 6 hours after I posted that 
comment and yes, so long as all the parallel inductances are in the 
sae magnetic field they will not decrease. When I read your 
description and say all the layers were in parallel I visualized 
several parallel inductors and the old formula poped in my head.
Ignoring at that point that since all the layers would be in the sae 
induced magnetic field  and the equation for parallel inductance is 
for inductors with independant magnetic fields! You've done a fine 
job with your multi-layer coils and I think shortly everyone will be 
adopting your idea! I certainly know I will! BTW I must have had half 
a dozen people correct me on that! I started feeling like a puppy 
that messed in the wrong spot and everyone passing by was rubbing my 
nose in it! I'm never afraid to admit when I'm wrong but some of you 
guys seem to be waiting for me to make a mistake, just so you can 
pounce on me! Geeezz.


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