Atomic,
You can use a parallel LC network but you loose control over the
oscillations inside the tank. I don't think audio modulation would work.
Plus you would need to limit the inrush current as it will look like a
short circuit to your switch.
A VTTC uses a parallel LC network but runs constant wave. A car with a
ignition coil uses a parallel LC network as there is a capacitor in
parallel with the ignition coil. This produces a transient AC wave.
I conducted an experiment a few years ago where I used a relay to dump a
charged 450v electrolytic into a ignition coil with a capacitor in parallel
with the primary. The sparks resembled a Tesla Coil (with branches and
leaves). The frequency was too low to produce a air discharge tho.
I don't know many other applications of a pulsed system that uses a
parallel LC network.
Tesla described this setup in his Colorado notes in July.
http://www.bibliotecapleyades.net/tesla/coloradonotes/coloradonotes03.htm#Colorado
Springs Notes - July 1-31, 1899
He stated " It secures two chief advantages: 1) less current through the
break and more through the primary and 2) longer and better oscillation in
circuit including primary because it is easy to constitute such a system
without break with an extremely small resistance or frictional waste.".
He had the switch and tank cap in the opposite place to mine however. But I
don't think it would matter much.
For a system like this your only dumping the capacitors energy into a tuned
LC network. So while a faster switch time will help it's probably not that
crucial and your tank circuit can be as high or low as you want in
frequency.
That's why I think a SCR would work as it would only need to conduct 1 to
1000 times per second. Also it's not switching tank currents so reverse
voltage shouldn't be a problem and the energy switched will be reduced.
Also timing will also be less crucial as long as the coil has rung out
before the next pulse. I know next to nothing about IGBTs and other
semiconductors.
Keep in mind I've only made 10cm streamers so far with a thyratron. I need
to do a lot more work to get close to a decent system.
Also keep in mind I am a layman. I will defer to the experts on this group.
Cheers!
-Wil
On 02/10/2014 3:49 AM, "Atomic" <atomicrox@xxxxxxxxx> wrote:
> This is a very interesting idea, I didn't know you could just parallel the
> tank capacitor and primary like that.
>
> From what I understood the thyratron is working only as an interrupter.
> Excuse my ignorance, but wouldn't that make it possible to make a much
> simpler DRSSTC that uses a single IGBT/MOSFET in place of that thyratron?
> If it works that'd avoid most of the hassle in setting up/building a
> DRSSTC, and would still have the sound modulation and "traditional"
> streamers.
>
> On Mon, Sep 29, 2014 at 10:13 AM, William Howard <snakeprior@xxxxxxxxx>
> wrote:
>
> > Dear Group,
> > I was dredging through the list archives and found mention of SCRs being
> > successfully used by a man in a magnifier years ago.
> >
> > I found his website in the archives but it only has two pages:
> >
> >
> https://web.archive.org/web/20010519065013/http://home.hiwaay.net/~eburwell/
> >
> > I am continuing my work with thyratron pumped tesla coils and had the
> idea
> > of using an inductor to limit current into the parallel LC network (to
> > reduce stresses on the thyratron and pulse cap). It was good to see he
> had
> > already used the idea years ago to limit the current through the SCR.
> >
> > I know the conduction time and recovery is longer for a SCR than a H2
> > thyratron but seems as they are not shuffling energy between the inductor
> > and capacitor in the tank circuit it shouldn't matter. There would just
> be
> > a variable pulse rate at which the SCR discharges a capacitor into the
> > parallel tuned LC network. I would be looking at 200 to 2000 pps.
> >
> > Here is a schematic of my existing thyratron tesla coil, an SCR just need
> > be substituted:
> >
> >
> http://russianpoweredvttc.blogspot.com.au/2014/09/thyratron-tesla-coil-plans-theory-and.html?m=1
> >
> > A saturable reactor would need to be added to limit current through the
> > SCR.
> >
> > I find this idea attractive because SSTC are too difficult for me to
> build
> > and SCRs are pretty cheap.
> >
> > It would be a very simple thing to test. As a layman I have to ask is
> there
> > any flaws to this idea?
> >
> > Cheers!
> > -Wil
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
> >
> _______________________________________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/listinfo/tesla
>
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla