Re: A triggered SISG coil

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi Finn,

Happy to see you are doing SISG stuff ;-))

At 02:45 PM 10/31/2006, you wrote:
> All,
>
> When I saw the SISG coil, I saw an IGBT stack 
> with a safety gap across it. A basic building 
> block that needed a trigger mechanism to really 
> appeal to me. It should be triggerable even when 
> using DC-Resonant charging, and it should be elegant. 8-)
>
> I built a 2 section SISG because it would enable 
> me to find out all the elemental things that I 
> needed to know, and decided to start out with a transformer trigged SCR.
> I selected the gate trigger toroid according to 
> the TLAR criterium (That Looks About 
> Right)  :-D  and so that the center would hold 
> the insulation from RG214 antenna lead, because 
> the toroids will be parked at elevated potentials.
> The trigger wire is passed down the center of 
> the toroids, and current from a 25µF cap is 
> dumped down that wire controlled by an IGBT and a couple of triple5`s.
>
> At the present moment, the circuitry looks like this:
> http://home5.inet.tele.dk/f-hammer/boards.jpg
>
> There are 4 250V sidacs in series, and the SCR 
> bridges the bottom 3. Therefore I can trigger 
> from 250Volts and up, and the top SIDAC will 
> turn off the current in the string, in case the SCR should be unable to do so.
> Suppose that I connect this gap to a resonant DC 
> supply, which has from 250 to 499 volts on it. I 
> can trigger it. After the ringdown the capacitor 
> will be charged up to 998volts. The gap can hold it off untill I trigger it.
> The way I wanted it.
>
> It works great, although I am unable to get the 
> fast charging times that you get, Terry:

The charging time gets better at higher firing voltage and bigger primary caps.

http://drsstc.com/~piranha/PIRANHA/SISG-Timing-Calc.pdf

Yours looks fine.  The main cap tend to overshoot 
to about 30V but quickly drops back down.  The 
gate voltage hits a big flat spot as it turns 
on.  The primary start up current looks 
fine.  This program might be of interest:

http://drsstc.com/~sisg/files/SISG-Timing-Calc-100.zip

> http://home5.inet.tele.dk/f-hammer/250n.jpg
> Yellow is main cap
> cyan is pri. current
> magenta is gate
> Anyway, the final scope check without breakout:
> http://home5.inet.tele.dk/f-hammer/ready.jpg
>
> Before first light @ 988V off a single CD 150nF 942/2000 and about 3 inches
> http://home5.inet.tele.dk/f-hammer/first.jpg
> Nothing like a first light, particularly not when it is a real "first"

I think you will like the SISG 
stuff!!  Triggering has never been figured out 
before.  Happy to see you are working on that too ;-)))

Cheers,

        Terry


> Cheers, Finn Hammer