Re: [TCML] Spark gaps, Solid state switches and diodes

[Stephen Hiscock <stephenhiscock@xxxxxxxxx>]

Bart and fin wrote:
"I get around 600 something turns....... "
"Yes, 648 turns at 32 tpi. I would expect Ipeak to range 185A to 1130A 
(15/30 up to 15/180). The primary details are important as geometry 
greatly influences Lpri and thus Ipeak. Top loads play a role also since 
primary resonance is based on an accurate f2 with all components in 
place. So if the system is listed in some detail, then Ipeak is better 
guesstimated."

Sorry Bart, Finn and others I must have been drunk when I wrote those 
figures,
The figures I gave you are wrong, but How were the figures above calculated?

I meant to say that the Primary is 30 to 100 micro Henries (not 
microFarads) sorry silly mistake.
and the Secondary is 30.25 inches winding length at 32 turns/inch ( 
again sorry) so 968 turns total
the former is 6.5inches diamater
The top toroid is 6 inch diameter ring and 6 inch diameter inner ring 
and 18 inch total outside diameter
eg: (circles represent the toroid) = in courier font it should look ok
 OOO           OOO
OOOOO---------OOOOO
 OOO           OOO             
|<-6->|<--6-->|<-6->|
|<----18 inches---->|

yeah the Primary circuit would have two of my transformers as a minimum 
(and 6 at a maximum)
I fired it up the other night I used 2 transformers rated at 15kV and 
30mA each
so 15,000 volts at 60mA.
12nF is my primary capacitance (but as a maximum I could have 36nF)
The primary was tapped at the 10th turn out from the middle. (and as a 
maximum could be the 4th turn - but its not working properly)
The primary is 12.5 turns total Turns
The dimensions are 13.5 inches inside diameter and 37 inches outside 
diameter.
with 1 inch between turns.
as it is at the moment I'm only getting 6 inch sparks at the best tuning!

(but sometimes I would hook up extra capacitance and transformers)
each transformer I have is 15,000 @ 30mA so my capacitance for each 
transformer should be 6nF right?

The tuning point for the biggest capacitance I can't verify because I 
think my capacitor died.
But it should scale up right when I repair the capacitor bank?
just like the primary transformers? eg if I use 2 x the capacitance then 
the peak current should be twice as large?

Is that enough info for a ball park Ipeak figure so I can work what 
IGBT's I need for a SISG?

Thanks
Stephen


bartb wrote:
> Yes, 648 turns at 32 tpi. I would expect Ipeak to range 185A to 1130A 
> (15/30 up to 15/180). The primary details are important as geometry 
> greatly influences Lpri and thus Ipeak. Top loads play a role also 
> since primary resonance is based on an accurate f2 with all components 
> in place. So if the system is listed in some detail, then Ipeak is 
> better guesstimated.
>
> Regards,
> Bart
>
> Finn Hammer wrote:
> > Stephen Hiscock skrev:
> > > Hello Fin Hammer,
> > > thank you for helping me out!.
> > >
> > > I've done some basic Calculations.
> > > Here is the basic config of the coil.
> > > 6.5'' Diameter, 20.25 winding length and 32 turns/inch so about 968 
> > > turns in total.
> > > wound on PVC former.
> >
> > I get around 600 something turns.......
> > > The primary is 12.5 turns 13.5 inside diameter and 37 inches outside 
> > > diameter.
> > > and in inch between turns. giving inductance range of 30 - 100uF 
> > > fopr tuning
> > I would expect henries here......
> > > the Capacitor is 6.4nF per transformer as they are 15kV at 30mA each.
> > > so giving a range of 6.4nF to 38.4nF depending on how many I hookup.
> > >
> > > you sent me this:
> > > Ipeak is a relation to Lpri, Cpri and Vmax.
> > >
> > > First calculate Zpri =>sqrt(Lpri/Cpri)
> > > so from this my Impedance is 781 to 125
> > > Then Ipeak => Vmax/Zpri = 21,213 / 125 = 169
> > > or 21,213 / 781 = 27
> > > and Ipeak ranges from 27 to 169 Amps (this seems a bit low)
> > > is this correct?
> > >
> > > So I'm guessing the standard design will work fine - but just lots 
> > > in series?
> > >
> > > Stephen
> >
> >
> > Could you supply tuning point for the biggest capacitor you use. This 
> > means: how many turns do you have engaged when all caps are in the 
> > circuit.
> > From this we can calculate Lpri needed to calculate Ipeak.
> >
> > Cheers, Finn Hammer
> > _______________________________________________
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