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RE: double wound secondary (fwd)
---------- Forwarded message ----------
Date: Tue, 02 Oct 2007 23:01:00 +0000
From: sparktron01@xxxxxxxxxxx
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: double wound secondary (fwd)
Hi Colin
Correct, and also gives advantage of large inductance / low loss in a
small footprint. In most cases, a secondary / extra coil with higher inductance
will outperform a coil with lower inductance. Alex and I are looking at winding
small form factor multiple layer coils like this to allow much higher
current capacity (his dynamite coil [2.375 x 12.5"] failed from overtemp
NOT overvoltage). In a magnifier producing simultaneous 10-12' streamers
(2 or 3) from a 12" long coil. And yes I have on video tape and showed
at Ed Wingate's Teslathon this past August.
Regards
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA. USA
-------------- Original message ----------------------
From: "Tesla list" <tesla@xxxxxxxxxx>
>
> ---------- Forwarded message ----------
> Date: Tue, 2 Oct 2007 09:21:25 +0100
> From: Colin Dancer <colind@xxxxxxxxxxxxxx>
> To: 'Tesla list' <tesla@xxxxxxxxxx>
> Subject: RE: double wound secondary (fwd)
>
> Hi Dave,
>
> I assume the 4x inductance compared to the bifilar coil is because you get
> approximately twice the number of turns in each layer (because the wires are
> close wound) as you would with a bifilar coil (where the wires are very
> roughly spaced a wires diameter apart)?
>
> Colin.
>
> -----Original Message-----
> From: Tesla list [mailto:tesla@xxxxxxxxxx]
> Sent: 02 October 2007 03:53
> To: tesla@xxxxxxxxxx
> Subject: RE: double wound secondary (fwd)
>
>
> ---------- 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
>
> -------------- Original message ----------------------
> From: "Tesla list" <tesla@xxxxxxxxxx>
> >
> > ---------- Forwarded message ----------
> > Date: Mon, 1 Oct 2007 10:06:33 -0400
> > From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: RE: double wound secondary (fwd)
> >
> >
> > Thanks guys,
> > I understand much better now.
> > Scott Bogard.
> >
> > > Date: Sun, 30 Sep 2007 08:35:57 -0600
> > > From: tesla@xxxxxxxxxx
> > > To: tesla@xxxxxxxxxx
> > > Subject: Re: double wound secondary (fwd)
> > >
> > >
> > > ---------- Forwarded message ----------
> > > Date: Sun, 30 Sep 2007 11:06:50 -0300
> > > From: Antonio Carlos M. de Queiroz <acmdq@xxxxxxxxxx>
> > > To: Tesla list <tesla@xxxxxxxxxx>
> > > Subject: Re: double wound secondary (fwd)
> > >
> > > Tesla list wrote:
> > > > ---------- Forwarded message ----------
> > > > Date: Sat, 29 Sep 2007 18:24:54 -0400
> > > > From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> > > > To: tesla@xxxxxxxxxx
> > > > Subject: double wound secondary
> > > >
> > > >
> > > > Hey everybody,
> > > > I know, this topic has been covered an awful lot in the
> > > > archives, I looked; but there seems to be some disagreement,
> > > > weather it is good or bad. It seems lately, everybody now thinks
> > > > it is not such a bad idea, as it decreases the resistance,
> > > > therefore increasing output. But, from what I know of formulas
> > > > and such, two inductors (since a coil is essentially an
> > > > inductor) in parallel decreases the inductance, which should
> > > > decrease voltage out? Does this situation not apply with a
> > > > transformer, or does the resistance decrease make that much of a
> difference to make up for it?
> > > > Or, does nobody actually know why it works so well? Just curious
> > > > (and considering double winding my 6-in secondary). Scott Bogard.
> > > >
> > > > _________________________________________________________________
> > > Two coupled inductors in parallel, with bifilar winding and high
> > > coupling (M=sqrt(L1*L2)), act as a single inductor with L=L1=L2=M.
> > > The proof is easy.
> > > It remains to be seen if the loss is smaller than when using a
> > > single wire with the same area of the two wires used in the bifilar
> winding.
> > > You can probably use a simulator as Javatc, that calculates wire
> > > losses, considering a single coil with the total number of turns
> > > with the two wires, and then divide the resulting resistance by 4 to
> > > obtain the resistance of the bifilar coil. Compare then with what
> > > happens with a wire with doubled area and single winding. In
> > > principle, I would expect similar results, or advantage for the
> > > single wire winding because there would be space between the turns,
> reducing the proximity effect, if the winding length is kept.
> > > Note that using the same winding length you can use a wire with
> > > twice the diameter, and so four times the area. The losses must be
> > > smaller in this case.
> > >
> > > Antonio Carlos M. de Queiroz
> > >
> > >
> > >
> >
> > _________________________________________________________________
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