Re: double wound secondary (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Tue, 02 Oct 2007 23:56:40 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: double wound secondary (fwd)

Yes, I stand corrected and I know better. Not sure why I had parallel on 
the brain. I was wondering who was going to point out my horrible 
mistake after I re-read my own post tonight. Yes Gary, exactly correct 
as you stated. Series will add and if it is tightly coupled, it might 
approach 4X.

 From a high voltage mechanical standpoint, how does one wind a 2 layer 
series connected Tesla Coil? Somethings not right. I think that's why I 
stated parallel and inversed my inductance relationship. The Q threw me 
as well down this same path.

Maybe Dave can help state if this is a series connected set of windings 
or if they are two parallel connected windings. If they are parallel, 4X 
is not possible. Should be near the same as a single winding.

Take care,
Bart

Tesla list wrote:

>---------- Forwarded message ----------
>Date: Wed, 3 Oct 2007 13:50:24 -0400
>From: "Lau, Gary" <Gary.Lau@xxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: RE: double wound secondary (fwd)
>
>No!  Inductors in parallel do not add.  If they are tightly coupled and
>identical in value, the net inductance approaches that of a single coil.
>If the two identical tightly coupled coils are wired in SERIES, the net
>value then approaches 4X the individual value.  If the series coils were
>not coupled, the net value would be 2X.  See
>http://en.wikipedia.org/wiki/Series_and_parallel_circuits
>
>Gary Lau
>MA, USA
>
>  
>
>>From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
>>To: Tesla list <tesla@xxxxxxxxxx>
>>Subject: Re: double wound secondary (fwd)
>>
>>Hi Dave,
>>
>>The Q isn't as neat (in my little book) as the inductance. The only
>>    
>>
>way
>  
>
>>possible I can account for this is if the two windings at the bottom
>>    
>>
>and
>  
>
>>top are in parallel and very close proximity. We know inductors in
>>parallel add. But, when current is flowing and if the two inductors
>>    
>>
>are
>  
>
>>in "that" type of proximity (and position) winding for winding, then
>>    
>>
>we
>  
>
>>now have the currents in both inductors doubling up on the flux (the
>>density is double on both windings). This would certainly result in a
>>    
>>
>4x
>  
>
>>(or about) inductance. I've never done that with a coil, but from an
>>    
>>
>arm
>  
>
>>chair physics view, it makes perfect sense that you would have 4X the
>>    
>>
>L.
>  
>
>>One of the goofy things not always realized with the multiturn coil
>>formula's (air core or otherwise) is that that a series connection is
>>assumed. You must have 2 parallel wires in this type of close
>>    
>>
>proximity
>  
>
>>to achieve this. Very cool!
>>
>>Take care,
>>Bart
>>
>>    
>>
>>>---------- Forwarded message ----------
>>>Date: Tue, 02 Oct 2007 01:32:13 +0000
>>>From: sparktron01@xxxxxxxxxxx
>>>To: Tesla list <tesla@xxxxxxxxxx>
>>>Subject: RE: double wound secondary (fwd)
>>>
>>>Antonio
>>>
>>>Gary Weaver has posted several times (and I have built) a "multiple
>>>      
>>>
>layer"
>  
>
>>>coil that is not specifically a bifilar wound coil.  Wind one layer
>>>      
>>>
>_close
>  
>
>>>wound_ then wind another layer on top of and in "groves" between
>>>      
>>>
>adjacent
>  
>
>>>turns of lower winding layer.
>>>
>>>By careful arrangement of individual wire entrance and exit into
>>>      
>>>
>windings,
>  
>
>>>maximum winding error of only +/- 1 turn (much less is practical)
>>>      
>>>
>will
>  
>
>>>occur.
>>>
>>>I have wound such a coil with two layers, and have noticed a MUCH
>>>      
>>>
>higher Q
>  
>
>>>then a typical "bifilar" wound coil.
>>>Inductance is ~4X higher to boot.  In this case, it is equivalent of
>>>      
>>>
>two
>  
>
>>>coils close wound in parallel, R would approach
>>>R/2 (proximity effects will make it larger, but still significantly
>>>      
>>>
>less R
>  
>
>>>then a single winding coil).
>>>
>>>Band pass testing with two winding coil revealed a bandpass so
>>>      
>>>
>narrow, I
>  
>
>>>could not fine tune VFO to maximum response, it would "jump" either
>>>      
>>>
>side of
>  
>
>>>response peak.  Gary noticed large improvement with two windings in
>>>parallel, less improvement from 2 to 3 layers in parallel.
>>>
>>>My coil was used on a VTTC powering a CO2 laser.
>>>
>>>Regards
>>>Dave Sharpe, TCBOR/HEAS
>>>Chesterfield, VA. USA
>>>      
>>>
>
>
>
>
>
>
>  
>