Re: Solid state gaps - what happened? (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Wed, 06 Jun 2007 23:25:07 +0200
From: Finn Hammer <f-h@xxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Solid state gaps - what happened? (fwd)

Gary, all

Being very proud to say that I was first with a triggered version of the 
SISG, and holder of the spark length record with a single section 
CM600HA brick SISG, the BRISG,
http://www.youtube.com/watch?v=vK17-CoB7LE
I can say that the work is still going on.
Much of the development effort was (sort of) documented over at 4HV.
Together with Daniel, I am currently building a medium sized coil with 
BRISG technology,  and this design will be presented here in due course.

Quenching is not much of an issue in the original SISG design, but it 
might become an issue with the DC resonant charging system used with the 
triggered version.
A BRISG, resonating at 50kHz, takes around 600uS to quench, and the 
current starts to climb trough the charging choke during this interval. 
This means that a substantial amount of energy is being stored in the 
choke, and that the final voltage on the primary cap shoots higher than 
twice the supply voltage, as is usually associated with this topology. I 
am not yet sure if this is good or bad.
Adding a quenching feature is trivial, however.

Terry`s original design, the PIRANHA, contained a hard to understand 
voltage doubler, which might have kept people from jumping in.

We should not forget that Terry took the PIRANHA off the net due to 
concerns about safety.

While it is true that a bridge topology has the potential (pun?) to 
produce longer sparks with 4 units of silicon, than a SISG has, this is 
only true as long as these units of silicon are still semiconductable. 
They still tend to "wear out fast" every once in a while, something that 
does not seem to be the trend with SISG silicon.

So although I still dream about joining the select group of individuals 
that have designed their own bridge driver, I stick with the BRISG solid 
state gap in the *mean* time.

Cheers, Finn Hammer

Tesla list skrev:
> ---------- Forwarded message ----------
> Date: Wed, 6 Jun 2007 15:29:06 -0400
> From: "Lau, Gary" <Gary.Lau@xxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Solid state gaps - what happened?
> 
> Just about a year ago Terry Fritz came up with a very clever, modular
> IGBT-based replacement to the static spark gap.  While the price tag was
> steep and far more complex than conventional gaps, the reported
> efficiency gains seemed hard to ignore.  It wasn't clear to me if the
> SISG was truly a drop-in replacement to conventional gaps, but it seemed
> to hold great promise, considering the ever-decreasing cost of silicon.
> I recall there was ongoing work on triggered versions too.  I don't
> recall if quenching (or lack there-of) was thought to be an issue.
> 
> Now a year later, not a word to be heard on the topic.  I'm just
> wondering - was the cost just too high and the practical efficiency gain
> didn't merit the cost, or if one is going the spendy/complex solid state
> route, DRSSTC's do better, or did we just forget about it without Terry
> to tout it?
> 
> Regards, Gary Lau
> MA, USA
> 
> 
> 
> 
>