SISG PIRANHA Charging Theory...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi All,

In interesting off list thing about how PIRANHA's charging circuit 
works and how little is understood about it :o))

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Steve said:

> "Terry, I never quite understood your voltage doubler charging arrangement."

"I" never quite understood how PIRANHA's charging works 
either  :o))   The "computer" figured it out while I was randomly 
trying different things.  But the actual coil does work just like the 
MicroSim model, so it "does" work.

Here is what I know:

The MOT voltage can be fairly low (like 105VAC) to help keep the MOT 
out of saturation.

The primary cap is fairly "resonant" with the MOT which helps charge 
the two 330nF caps up to 1.5X the voltage.  The primary cap value is 
not super critical and 200 to 400nF seems to work pretty good too.

The system charges as a voltage doubler referenced to ground but 
discharges "floating".  So the caps really don't discharge with 
respect to ground.  Having the other cap discharge to a lower voltage 
helps the next cycle fire.  It is almost "preserving" the firing voltage.

The BPS is pretty sensitive to the actual line voltage (variac).  One 
can get from 60, 120, 240, "other" BPSs easily but it is touchy if 
you are trying to hit one exactly.  Often the firing is fairly 
chaotic.  ~240BPS seems like a nice area.  The streamers "like" the 
higher BPS and the chaotic nature of the thing.

Here is a MicroSim model:

http://drsstc.com/~piranha/PIRANHA/PIRANHA-MS-01.gif
http://drsstc.com/~piranha/PIRANHA/MicroSim/

The firing rate at 106VAC input is ~220 BPS as shown here:

http://drsstc.com/~piranha/PIRANHA/PIRANHA-MS-02.gif

But look at those cap voltages!!!

http://drsstc.com/~piranha/PIRANHA/PIRANHA-MS-03.gif

The waveforms on the two caps are "messy" but they add up to the 
bottom waveform which is able to fire the 165nF combined capacitance 
at 220 BPS at 6900V!

Nothing really gets hot and the 100 ohm resistors just get a little 
warm.  The system power is

220 x 1/2 165e-9 x 6900^2 = 864 watts.

The MicroSim model gives an RMS voltage of 106.066V and 9.668Arms:

http://drsstc.com/~piranha/PIRANHA/PIRANHA-MS-04.gif

So the VA is 1025.5.  If we look at the real input power:

http://drsstc.com/~piranha/PIRANHA/PIRANHA-MS-05.gif

We get 911.6 watts.  So the power factor is 88.9 Which is pretty good  :-D

The "loss" is 911.6 - 864 = 47.6 W  The RMS current through the 100 
ohm resistors is:

http://drsstc.com/~piranha/PIRANHA/PIRANHA-MS-06.gif

430mA so the power dissipation is 2 x 0.43^2 * 100 = 37 watts.  That 
only leaves 10Watts on the IGBTs and primary resistance!  0.25 ohms 
there seems "high"!  It is probably a little lower!  The IGBTs stay 
"cold" in the fan breeze.

So there, now you know just as much about it as I do  :-D  It is a 
bazaar thing and it works super good!!  But the charging stuff is not 
"easy" to comprehend.  I hope to figure it out "someday"  :-)

The PIRANHA is the only coil I use now and I have no desire to get 
out any of the others.  Simple, light, never breaks, runs forever, 
and is a super good performer off a single happily running MOT.  It 
is a scary coil in that it goes from dead silent to full power 
instantly, and it is loaded for bear!!  ;-)))

Obviously, it is the greatest Tesla coil design on Earth  :O)  I 
should probably advertise it more, but it will come in its time 
;-)  It is a little tougher to get across since between the MOT and 
the coil, "nothing" is "conventional" at all...  And I can still say 
that an SISG coil has "still" never blown up  :-D
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Cheers,

   Terry