SISG - PIRANHA Tesla coil first light!

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi All,

I have been working on a powerful version of the SISG Tesla coil.  I 
call it the "PIRANHA".  Although it has had many forms, it is finally 
getting to a point nearing being "done", so I thought I would give an update...

It uses a single MOT and two of Mark Dunn's SISG boards.  Firing 
voltage is somewhat adjustable by shorting sections of the SISG 
firing circuit with small brass bolts.  I don't have all the parts to 
run at full power yet, but it can easily hit 28 inches at 67% voltage 
at low BPS.  Break rate is "whatever it feels like" ;-) but about 60 
to 360 BPS depending on the variac setting.  Firing voltage is 2400V 
to 7200V in 300V increments.

Right now I don't have the right resistors and I really "should" make 
a new MMC for it, but every thing runs as planned.  At full power it 
should near 45 inch arcs to ground.  Some of the specs follow:

Typical:
240 BPS
6300Vfire
314kV peak output
33 Arms primary current(!)
650 Apeak primary current
2 x 8000V 330nF primary MMC caps in series
11 amps AC line current at 87% power factor.
Input voltage 100 - 110 VAC (keeps MOT out of saturation)

Actual power delivered to the streamer is about 450 watts.  Earlier 
testing has shown the SISG coils like higher BPS at some advantage to 
arc length so this does all that easily.  It's just about as much 
power as you can safely pull from a MOT without blowing everything up 
;-)  Primary RMS current is very high!  At 33 amps RMS each IGBT will 
dissipate about 22 watts.  Not a big deal with a fan breeze.  The 
present MMC will burn up anyway ;-)  So full power but "short" runs 
unless I want to spring $140 for a new super high RMS current MMC at 
twice the voltage.  I'll burn this one up first :o))

The charging circuit is "new and improved" now.  The old 1000 ohm 
resistor system would burn off 700W!!!  But the solution was trivial 
to simply place the charge resistors so the SISG shorts them out 
during firing.  Now they are 100 ohm resistors burning off just 50 
watts of power ;-))  This also make a dual MOT system possible with 
very high RMS current parts!  One could probably make a big pig 
system like this too.  You don't really need a ballast anymore.  The 
RMS current can easily be reduced as one wishes too.  With higher 
voltage, you don't really need big primary currents, but there is no 
reason not to push it since the MOTs can supply more current than one 
can use ;-))  The schematic is here:

http://drsstc.com/~piranha/PIRANHA/PIRANHA-SCH.pdf

There is not much to it all all!!  Just two simple resistors, two BIG 
microwave diodes, and a dual primary cap along with the SISG.  Note 
that this system will NOT work with a standard spark gap!  You get 
bonus points if you know "why" ;-))

Here are pictures of the "engine".  Everything is bolted to an 11 x 
14 inch piece of plywood:

http://drsstc.com/~piranha/PIRANHA/pictures/PIRANHA-001.JPG

http://drsstc.com/~piranha/PIRANHA/pictures/PIRANHA-002.JPG

All the files are here if you want to dig around:

http://drsstc.com/~piranha/PIRANHA/

But only these probably mean anything...

http://drsstc.com/~piranha/PIRANHA/ScanTesla8/output.txt

http://drsstc.com/~piranha/PIRANHA/MandK/PIRANHA.txt

Cheers,

	Terry