Re: The RAT coil.

["Tesla list" <tesla-at-xxxxxxxxxx>]

Original poster: "Finn Hammer" <f-hammer-at-post5.tele.dk> 

Bart, all,

The overshoot was unsuspected from simulations, however it is a common
occurrence with , particularly, LTR designs running at 100/120 BPS.

Richie Burnett has an excellent description of the phenomenon here:

http://www.staff.ncl.ac.uk/r.e.burnett/offset.html

The ripples that you see can not be from the ringdown, The trace is too
thich for that. Rather it must be some sort of resonnance btwn the
ballast and the MOT`s.

However, there is something fishy going on around just that particular
quench, because the cap starts out at a higher initial voltage there,
than at the other 2 ringdowns. Perhaps the effect of uneven electrode
spacing. I`l check that again before next run. Perhaps adjust trace
rotation on the scope too, it seems to be a bit off.
I have not yet had the time to view the ringdowns under streamer
loading, (the picture was taken discharging to a grounded rod, due to
space limitations)and apply delayed sweep to that portion, to zoom in on
details, but it is one of the first things that I will do, when I run
the coil again.

Cheers, Finn Hammer

Tesla list wrote:
> 
> Original poster: "Barton B. Anderson" <tesla123-at-pacbell-dot-net>
> 
> Finn, all,
> 
> The overshoot is interesting. The cap continues charging to a higher
value then
> when it finally discharges, the later portions of the ringdown continue
> outward.
> You can see the ripple on your screen. I wonder if this poor quenching on
these
> particular points?
> 
> Bart
> 
> Tesla list wrote:
> 
> > Original poster: "Finn Hammer" <f-hammer-at-post5.tele.dk>
> >
> > Richie, all
> >
> > Those flats,(which are the same flat, really, symmetric on each
> > halfphase) Have me baffeled too, something that I had not expected at
> > all. From simulations I had expected this:
> >
> > http://home5.inet.tele.dk/f-hammer/msim.jpg
> >
> > The overshoot before the break at 2mS is also unaccounted for. I guess
> > that it has to do with some peculiarity of the MOT`s, and I am
> > speculating that these beasts actually are wound on a core that has some
> > sort of square hysteresis curve or something. This could perhaps be
> > tailored to the application in the oven, and also explain why they
> > perform so well in tube coils. They are sort of peaky in responce.
> >
> > Cheers, Finn Hammer
> >
> > Tesla list wrote:
> > >
> > > Original poster: "R.E.Burnett" <R.E.Burnett-at-newcastle.ac.uk>
> > >
> > > Hi Finn,
> > >
> > > This looks like a very flexible Tesla Coil,  and is beautifully built
too.
> > > It should provide an excellent test bed for your research,  I wish I had
> > > one !
> > >
> > > I did some work with uneven spaced firings,  and the ability to adjust
> > > each firing point in real time is so valuable because there is a lot
> > > of interaction between each firing.
> > >
> > > I took a look at the charging voltage waveform shown on your page:
> > >
> > > http://home5.inet.tele.dk/f-hammer/charging.jpg
> > >
> > > The two flat portions in the trace are seem unusual.  I have never seen
> > > this behaviour before,  and I usually have the scope connected when I run
> > > my coil.  Do you have any idea what is happening in these periods where
> > > the voltage is almost constant ???
> > >                                                         Cheers,
> > >
> > >                                                         -Richie,
> > >
> > snip