Re: [TCML] Coupling

[Bert Hickman <bert@xxxxxxxxxxxxxxxxxxxxx>]

Clever approach, Mike!

You'd need to watch out for autotransformer effect bumping up voltage on 
the innermost turn. You might need to widen the gap between innermost 
turn and secondary but otherwise this should work.
Bert

mike tucknott via Tesla wrote:
> Hi All
>
> With a bipola coil would having 2 movable tap point work for changing 
> the coupling ?
> Say the coil need 5 turns to be in tune, you could built the primary 
> with 10 turns and you could move the inner and outer taps points in or 
> out but still keeping the 5 turns needed to keep the coil in tune, the 
> inner and outer turns passed the tap point would be electrialy dead so 
> to speak.
> Thoughts on this one guys.
>
> Cheers Mike T
>
>
> On 17/10/2020 00:43, Gary Lau wrote:
> > Hi Kurt,
> >
> > Splitting and separating the secondary seems like a great way to vary the
> > coupling, but one must also bear in mind that doing that will vary the 
> > Lsec
> > inductance and tuning.  I can't think of a way to vary only the 
> > coupling on
> > a bipolar coil, but I have never built one.
> >
> > Regards, Gary Lau
> > MA, USA
> >
> > On Fri, Oct 16, 2020 at 7:15 AM Kurt Schraner <k.schraner@xxxxxxxxxxx>
> > wrote:
> >
> > > ...just my 2 cents: cutting the bipolar secondary in 2 independently
> > > movable
> > > halfs could enable the control of the coupling (see the ASCII-sketch):
> > >
> > >                                      oooooooooooo
> > >      __________________           __________________
> > >     I__________________I         I__________________I     <---->
> > >
> > >                                      oooooooooooo
> > >
> > > ...the primary can be either of a solenoid or a flat spiral.
> > >
> > >   Regards, Kurt Schraner
> > >
> > > -----Ursprüngliche Nachricht-----
> > > Von: Tesla <tesla-bounces@xxxxxxxxxx> Im Auftrag von jimlux
> > > Gesendet: Freitag, 16. Oktober 2020 02:15
> > > An: tesla@xxxxxxxxxx
> > > Betreff: Re: [TCML] Coupling
> > >
> > > On 10/15/20 6:50 AM, Douglas Johnson wrote:
> > > > Thank you both, I think I know where to go from here on my current 
> > > > build.
> > > > My project is a larger bipolar than I have built to date. Secondary is
> > > 3.5"
> > > > dia. X 24" with .015 mag wire. By the time I built the primary it 
> > > > was 6"
> > > > long and I was getting "runners" on the secondary. I think my fix will
> > > > be going to a flat spiral primary.
> > > On a bipolar, it's hard to control the coupling on a solenoidal primary
> > > sliding it one way or the other doesn't change the flux distribution 
> > > very
> > > much.
> > >
> > > I'm not sure a flat is any better.
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--
Bert Hickman
Stoneridge Engineering LLC
Woodridge, Illinois, USA
http://www.capturedlightning.com
+1 630-964-2699
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