Re: variable inductor primary tuning (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 23 Jul 2007 21:07:38 -0400
From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
To: tesla@xxxxxxxxxx
Subject: Re: variable inductor primary tuning (fwd)

Greg, Others,
     I'll be a little more specific on the setup I had in mind, I was 
thinking on driving a very small LC primary to oscillate either a tiny 
minuscule secondary, or even a large flyback transformer.  It will run off 
of mains voltage (through a choke or ballast), and I intend to replace a 
spark gap, with a back to back pair of MOSFETs (opposite polarity) which 
will fire at X BPS from a signal generator (I don't have exact details, it 
is a work in progress) (this setup will be similar to the mains voltage AIC 
made by Jeff Behary).  I will calculate approximate values for the "tank 
cap" and primary inductance, to get the resonant frequency of either my tiny 
secondary, of flyback xformer.  But in order to make up for imperfections in 
the components (and more likely my calculations) I wanted a tunable primary, 
so I thought I might just wire a tap-able inductor in series with my primary 
coil, but I wasn't sure if this would work, although this variometer concept 
holds potential as well, I'll have to research the concept some more.  
Thanks.
Scott Bogard.


>From: "Tesla list" <tesla@xxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: Re: variable inductor primary tuning (fwd)
>Date: Mon, 23 Jul 2007 17:21:37 -0600 (MDT)
>
>
>---------- Forwarded message ----------
>Date: Mon, 23 Jul 2007 16:13:47 -0700 (PDT)
>From: G Hunter <dogbrain_39560@xxxxxxxxx>
>To: Tesla list <tesla@xxxxxxxxxx>
>Subject: Re: variable inductor primary tuning (fwd)
>
>I'm sure it works, but at what cost to efficiency and
>"Q"?  That's what I don't know.  Still, convenient,
>low cost construction & effortless tuning may
>outweight the need to milk every possible centimeter
>of spark from the available power supply.  Your call.
>
>Search the TCML archive as well as "Google" for the
>word: "variometer".  Here's one Google link:
>
>http://www.qsl.net/in3otd/variodes.html
>
>There are several others.  Don't shy away from amateur
>radio sites.  These have the best info on variometer
>design and construction.  Hams use them as electrical
>length adjusters for LF and VLF antennas.
>
>Since you need only a very modest adjustment range
>(+/- a few microhenries), you can scale yours way down
>from the antena tuner plans.
>
>If you get one working, kindly share your experience
>with the list.  I'm interested in this subject too.
>
>YT,
>
>Greg
>
>--- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> >
> > ---------- Forwarded message ----------
> > Date: Sun, 22 Jul 2007 22:10:38 -0400
> > From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
> > To: tesla@xxxxxxxxxx
> > Subject: variable inductor primary tuning
> >
> > Hey guys,
> >      If one was building a small TC or other
> > resonant circuit and wanted to
> > make a fixed primary (without taps) would one be
> > able to put some kind of
> > variable inductor in series with the primary coil,
> > and vary the tuning in
> > this manner?  I would assume this would not be the
> > most efficient way, but
> > does it actually work this way or not.  Thanks.
> > Scott Bogard.
> >
> >
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