Re: OLTC idea...

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "K. C. Herrick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>

Wells, Terry & all from Ken Herrick-

I've always thought that this kind of thing was a good idea: cause as
much of the primary circuit's magnetic flux as possible to pass thru the
secondary rather than go elsewhere.  My s.s. system started out with 1
(equivalent) primary turn but I've increased that now to 3 in order to
reduce the magnetizing current.  I keep all the primary's
current-carrying components (MOSFETs, capacitors) as close to the
location of the actual conductors as possible.  But I need to use
discrete capacitors since mine are large electrolytics (driving an
untuned primary).

It seems to me that Terry's capacitors are indeed "part of the inductive
loop".  Their inductance comprises part of the total primary inductance
and they appear to be physically oriented such that the flux from that
inductance goes pretty much where the flux from the copper coil goes.

I've made a paper-design of a spark-gap system in which the primary's
multiple capacitors, and multiple spark gaps, are arrayed in a circle
co-planar with a copper-tubing coil so as to constitute not only the "C"
of the L-C primary but also one of the 6 turns of conductor.  So far,
alas, it's only on paper...

Ken Herrick


On Tue, 03 Sep 2002 21:49:27 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> 
> Hi Wells,
> 
> I was originally thinking of having the primary caps as part of the
> inductive loop.  As it "turned out", the caps were brought outside 
> the
> loop.  I was afraid that the cap being "part" of the 4500Amp primary 
> may do
> something unforseen.  I don't "know" of anything bad, but I didn't 
> want to
> take a chance and the thing sort of worked out to what it is now.  I 
> think
> Ken's coil may use this for his single loop primary?
> 
> Cheers,
> 
>         Terry
> 
> 
> At 08:30 PM 9/3/2002 -0700, you wrote:
> >Hi Terry, all, 
> >
> >I am writing with a kind of an oddball idea which I had a few years 
> ago,
> >and actually made it work on my little desktop coil, and had 
> forgotten
> >it completely until today as I was daydreaming...maybe it's a 
> concept
> >that would have some use in the OLTC realm, who knows...
> >
> >Let me first take you back to the heyday of rolled poly caps and 
> Richard
> >Quick gaps, about the time when the first little blue boxy-looking 
> phillips
> >caps were being soldered together and all the "high power guys" 
> were
> >scoffing at the idea of an MMC being used for anything but a little 
> coil...A
> >post about rolled poly caps talked about reducing inductance in the 
> rolled
> >caps by using strips of foil every turn or two as a terminal, so 
> that
> >the charge didn't have to travel around and around the plate to get 
> to
> >the terminal. 
> >
> >well, I got to thinking, what if you could make a cap that had 
> about
> >the inducance of a primary, wrapped around a tube which would go 
> around
> >the secondary and serve as both the primary and cap in one unit-I 
> think
> >I called it a capductor or incapacitator or something, and got some 
> copper
> >foil and twisted one up. The way it worked was that each plate had 
> it's
> >terminal at opposing ends, so that the charge had to travel in the 
> direction
> >that contributed to the magnetic field instead of cancelling it 
> out.
> >I wrapped the plate/poly/plate/poly stack around a tube which fit 
> around
> >my secondary with about an inch of clearance, and was about 1/3 as 
> high
> >as my secondary, with about 8 turns total. The gap and supply went 
> in
> >parallel to the "incapacitator", and it resonated with itself. (I 
> know,
> >hurts to think about, but basically the inductive properties and 
> the
> >capacitive properties produced a unit that resonated at the same 
> frequency
> >as my secondary, and served as a primary and cap in one). It 
> actually
> >worked! I got the values so close on the first try that I was able 
> to
> >tune with 3/4 turn of  refrig. tubing, off axis. 
> >
> >Anyway, my reasoning was that it would be the lowest loss 
> arrangement
> >ever, because the energy wouldn't have to travel out of the 
> capacitor,
> >into the primary, and back, but would just be rocking back and 
> forth
> >along the plates of the incapacitator. 
> >
> >I dunno, maybe you could construct a poly and copper plate cap that 
> would
> >wrap around the base of the OLTC, and simply connect the IGBT 
> "brick"
> >across the leads of the incapacitator? you would have to get the 
> values
> >right in designing the thing, but that shouldn't be too hard, I did 
> it
> >with wintesla. 
> >
> >Anyway, just an idea, I thought it was a neat concept at the time, 
> but
> >never got much farther than cobble-up. But it was neat seeing 
> "noodle
> >theory" turn into reality :>). 
> >
> >Does this sound like anything you could use?
> >
> >-- 
> >Wells Campbell
> >wellscampbell-at-onebox-dot-com
> >
> > 
> >
> 
> 
> 
>