Re: [TCML] MOT stack replaced with PT, performance gone

[SusaX2 X2 <susax2@xxxxxxxxx>]

It is starting to make some sense for me. Too bad I don't have a scope, but
I'll take your word for that. To comprehend resonant charging I'll have to
do some more research, after all, there should be a performance gain in it.
And if inductive kick with a gapped ballast and PFC capacitors are taken
along in the equation things become even more complex  for a calculated
approach. To prevent the 'errorr' in the trial and error method, I'll stick
with my large bottle capacitor for now, don't want to see a 942c mmc going
up in smoke..
Thanks,
Mark

2012/7/13 Scott Bogard <sdbogard@xxxxxxxxx>

> Hi Mark, Ted,
>      That is interesting, and it sort of makes sense.  To say what Ted did
> in simpler terms, even though the power supply (whether MOTs or a
> PT) ratings should not matter, and even though the power supply
> theoretically does not effect the resonate frequency, well, it does...  It
> is a bit complex but think of the secondary of the power supply like an
> inductor in parallel with the TC primary and tank cap, it won't effect Fres
> of the TC secondary, but it will effect the primary tuning point.  This
> principal is what is behind "resonate charging" of the tank cap.  And as
> Ted said, MOTs usually have a high leakage inductance, so the Fres of the
> primary at any given tap point will be more off from the theoretical value
> than with the PT, which has lower leakage inductance, or maybe the other
> way around...  Does that make sense?  If you scoped your primary before and
> after you would probably see the same frequency with differant tap points
> on differant transformers, due to the inductance of the transformers
> themselves.  I never thought about it that way, good call Ted...  This also
> solves a huge personal mystery for me, my best running coil ever ran at
> like double the predicted turns of JavaTC, and it was a twin MOT coil with
> no ballast, probably had huge leakage inductance being part of the tuning
> factor.  Fascinating...
>
> Scott Bogard.
>
> On Fri, Jul 13, 2012 at 8:18 AM, SusaX2 X2 <susax2@xxxxxxxxx> wrote:
>
> > Hi Ted, Scott,
> >
> > The PT is 100:6000V, so with a slightly overvolted input, voltage output
> > should be about the same as with 4 MOT's.
> > To get a higher power throughput I've doubled the flying electrodes,
> going
> > from 200 to 400BPS. Did a run, still nothing..
> >
> > Leaving the theoretical approach for what it was, I tuned the primary tap
> > inward. And here you go, the coil came back to life. With the MOT's, the
> > sweet spot was between 5,5 and 6 turns. It started sparking again when I
> > putting the tap a tad before the 5th turn. The sweet spot is now between
> 4
> > 2/3  and  4 5/6 turns.
> >
> > I am pleased with the result, but I don't understand what is going on in
> > reference to my calculation sheet. Please bear in mind my knowledge in
> this
> > matter is limited, but I've coped with the steep learning curve so far.
> > Since the secondary and topload are unchanged, Fres. should remain the
> > same.
> > On the primary side, Cp is unchanged. The primary 'L part' in the LC
> > calculation has just become more complex, at least for me I guess.
> >
> > Regards,
> > Mark
> >
> >
> >
> >
> > 2012/7/13 Tesla <tesla@xxxxxxxxxxxxxxx>
> >
> > > Greetings
> > >
> > > An aspect I'd consider is resonance with the leakage inductance and the
> > > primary cap in the MOT system.  Magnetically Shunted MOT's will have
> much
> > > higher leakage inductance ( I think at least 6Hy per MOT)  than the PT
> > > leading to significantly different dynamic charging of Cp with the PT I
> > > think
> > > Rgds
> > > Ted in NZ
> > >
> > > -----Original Message----- From: SusaX2 X2
> > > Sent: Thursday, July 12, 2012 1:56 PM
> > > To: Tesla Coil Mailing List
> > > Subject: [TCML] MOT stack replaced with PT, performance gone
> > >
> > >
> > > Hi,
> > >
> > > recently my 4MOT-stack died and I replaced it with a PT.
> > > I expected quite a performance gain, since it puts out twice the power
> of
> > > the 4 MOT's.
> > > But the completely opposite happened,
> > > from streamers well over 1 meter to feeble 10cm sparks.
> > > I also noticed the 200BPS SRSG fires very week, despite adjusting
> phasing
> > >
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