Re: If correct, this will change everything!!

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

Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>

Hi Malcolm,

At 06:53 PM 10/3/2004, you wrote:
>Hello Terry,
>             A few comments about your paper:
>
>- the notion of using high primary inductances to get primary
>currents to a low level has been recognized as being beneficial for a
>some time now. I did a quantitative analysis of this wrt spark gap
>coils pre-1998.

Yes!!  But it has new uses with IGBT drive coils were primary current needs 
to be kept lower.  So on old idea with state of the art electronics ;-))


>- there is typo in the text; I'm sure 250mH using 1/4" Cu tubing is a
>bit unrealistic for a coil that might be made transportable ;)  I
>note that mH reverts to uH further along in the text.

Yup ;o))


>- a 71 Ohm surge impedance is not terribly exceptional.
>
>- the secondary losses are going to be rather high unless the coil is
>physically huge in which case the associated capacitance is going to
>be correspondingly high.

The higher capacitance is helpful in keeping the resonant frequency low so 
no problem there!  We need to beware secondary losses, but these coils are 
pushing 13 feet ;-))

http://hot-streamer-dot-com/srward16/DRSSTC-2.htm

Even the old OLTC technology has gotten pretty good!!

http://www.scopeboy-dot-com/tesla/t4spec.html

Secondary losses seem to be very manageable now days.


>- You appear to be starting out with a charged primary capacitor
>which rings down in conventional disruptive fashion. Have I
>misinterpreted your scope shots?

Excellent observation!!  It was the inductor that was accidently charged 
with current.  The primary cap had an initial condition of 10 volts left 
one it.  Trivial capacitor charge, but a 333 amp inductor initial charge of 
current due to the low primary circuit resistance!!


>I suspect you saw the same nirvana I did a few months ago at which
>point I was reminded by a couple of list members that in the process
>of ringing the system up, the double coupling artifacts do not allow
>one to just ring up and up without intermediate energy trades.

DRSSTCs can add power throughout the firing cycle unlike our fixed break 
energy capacitor discharge coils.  In fact, that is the only time they can 
add energy to the system, as odd as that sounds.  That may be very 
important here very quickly!!  Energy trades and the losses (arc) perhaps 
can be controlled to an optimal level.  In fact, we know they can...


>(Aside - I realized why after considering that a conventional
>disruptive coil has the same topology save that its "supply" is
>effectively a zero Ohm piece of wire; both conditions are modelled as
>being driven from voltage sources but in the old disruptive case, the
>voltage source has zero output) - end aside.
>
>The kind of analogue I had in mind was Dr Gary Johnson's coil which
>actually took in the mS region to ring up to a useful level in that
>fashion with a modest drive circuit.

Yes, but now that they are putting out 13 foot arcs...  Things have gotten 
"hot" ;-))

>       The results look far too good to be true - you have to pour a
>considerable aomunt of energy into the secondary to get its voltage
>to the point where you can generate some stretching (i.e. you are not
>dealing with a drawn arc which to my mind is implied by the secondary
>"load". Ideally, you want the secondary to ring up with as little
>load as possible to get the output voltage high before letting go.
>In short, I think the model is flawed.

And so it is ;-))  I'll try not to mess up the next time.  And, the time 
after that :o))

Cheers,

         Terry



>Malcolm
>
>
>On 3 Oct 2004, at 13:02, Tesla list wrote:
>
> > Original poster: Terry Fritz <teslalist-at-twfpowerelectronics-dot-com>
> >
> > Hi All,
> >
> > I was working on DRSSTC theory last night.  So I ran some models.
> > Slept on it...  Wrote it down this morning on the laptop...
> >
> > Just like the OLTC was optimized to giant low voltage currents, we can
> > optimize the DRSSTC to use small primary currents but higher voltages.
> >  Then we can take advantage of the fact they have vast power reserves
> > unlike a cap discharge coil that only has a fixed amount of bang
> > energy.  Then we can optimize it all to run off "little cheap"
> > IGBTs...  This all went pretty quick, but unless I messed up, the
> > whole world of coiling will change now...
> >
> > http://hot-streamer-dot-com/temp/DRSSTC-Optimization.pdf
> >
> > http://hot-streamer-dot-com/temp/DRSSTC.sch
> >
> > Of course, if I made some giant boo boo, forget I ever brought it up
> > ;-))
> >
> > Cheers,
> >
> >  Terry
> >
> >
> >