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

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Thu, 7 Jun 2007 00:10:47 -0500
From: Drake Schutt <drake89@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Solid state gaps - what happened? (fwd)

Am I correctly reading the 85VA=3-4' streamers and 110VA=5'???  Wow knew
solid state was good, but not that good!

On 6/6/07, Tesla list <tesla@xxxxxxxxxx> wrote:
>
>
> ---------- Forwarded message ----------
> Date: Wed, 6 Jun 2007 22:08:25 -0500
> From: Mark R Dunn <teslamark@xxxxxxxxxxxxx>
> To: 'Tesla list' <tesla@xxxxxxxxxx>
> Subject: RE: Solid state gaps - what happened? (fwd)
>
>
>
> Gary:
>
>
>
> There have been plenty of posts on SISG, but little discussion.
>
> My SISG coil has been in operation since June 2006 and the current
> technical
> info is available at:
>
>
>
> http://www.teslaboys.com/SISG/index.html
>
>
>
> I have shipped SISG boards to a number of coilers on the list.
>
>
>
> My coil uses (2) MOT's and (4) SISG boards(16 circuits X 900volt).
>
> Typically I tap at 13 or 14 circuits so I am running at 11.7 to 12.6 KV
> threshold voltage).  The SISG is elegant compared to a spark gap.  From my
> perspective the spark gap is history.
>
>
>
> My camera hasn't produced very good pics of the streamers, but a couple of
> weeks ago I did a demo for Steve Ward and Jeff Larson.  Jeff got some
> great
> pics and when I get them I will put them up on the website.
>
>
>
> My coil normally runs in the basement and I have it severely current
> limited
> to keep the sparks off the walls, sewer pipes, equipment, etc.  Right now
> it
> runs with 3 to 4 foot streamers, but I am only feeding the MOT's around
> 82-85 VAC.  Cranked up to 100 to 110 VAC, it can do 5 to 6 footers, but I
> can't do extensive testing of that indoors and have not had time for
> extensive outdoor testing (My kids play Travel Soccer AND Baseball).
>
>
>
> The quenching has not been an issue.  The waveform decays on its own in
> about 40 uS.  As a result we have been able to decrease the gate shut-off
> resistor value to as low as 680 ohm.  There are waveforms on the website.
>
>
>
> One of the tricky issues with SISG is that you cannot independently
> control
> BPS.  (Note: Finn Hammer built a triggered version)  You control BPS by
> balancing the tank cap size against the impedance of the
> transformers.  This
> concept seems a bit hard to grasp for some people - I did not get it at
> first myself.  When I first fired up my SISG coil, my tank cap was way to
> small for my transformer impedance and my BPS was 1200!  Now that I have a
> properly sized tank cap, I run around 120 BPS.
>
>
>
> You mentioned cost...I think you will find that by the time you finish a
> good rotary spark gap, the cost is far greater than SISG.
>
>
>
> Terry pulled his Piranha site down because of a lack of the lack of
> respect
> that some coilers expressed regarding the safety issues regarding the tank
> circuit.  These MOT based designs can push 200 mA into the tank circuit
> during charging and because of the diodes SISG is a pulsed DC
> design.  There
> is real danger that the tank cap can remain charged on shutdown.  I have
> checked mine with HV probe and it takes about 60 to 90 seconds to
> discharge
> thru the safety resistors paralleled with the caps in the MMC.
>
>
>
> I have ongoing off list discussions with TCML members concerning SISG
> weekly
> and sometimes daily.  The posts I and others have made to encourage
> discussion have for the most part been ignored so we figured that most
> people were not interested.
>
>
>
> Mark
>
>
>
>
>
>
>
> >---------- 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
>
>
>
>
>
>
>
>