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New Baby!!! SISG!! 2:52PM (MST) weighing in at 0.78 Oz / 900Volts at 800 Amps!!!!!!

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>


The SIDAC/IGBT Spark Gap "SISG" was BORN today ;-))

Here is the first picture:


The inductor was 634nH, thus the fast ring down, (like a dead short jumper wire) ;-)) 260kHz with 600nF of capacitance firing at 900V.

"800 Amps" at "0.05 ohms" effective resistance ;-)) In most cases, even the SUPER TO-247 will not need a heat sink ;-)) Mark at 460 BPS will need little ones ;-))

Hehehe!! just scope pictures, but no "sparks"... But us "scientists" now that the "sparks are trivial now" :o))))

The modules work in series just fine and a single module can be "way overloaded" with NO apparent damage!! I drove 700 amps through the old one many times and it lived just fine...

More pics here:


Note the extra kludged on components... I thought getting ride of the wire inductance on a "real PC board" would fix the gate voltage going too high problem. But not quite at 800 amps =:O


35.6 volts on the gate is not terrible... But adding another TVS (I guess "transorb" is "old now"...) to the gate would fix this and probably make the module more "streamer hit proof" if it got hit. I wondered too, if it was just probe error being near an 800 amp signal... So I got a 20V and 15V TVS and added them to see:


It is nice to know that those $1200 probes really do work perfectly :-))) The extra transorb - Opps... "TVS" clamps the voltage right on and does not hurt the turn-on margin at all... So it is a new part now... That emitter inductance is a "real thing"....

Close ups of the on resistance:


The current through and the voltage across the gap.

A calculated dynamic resistance (three ways)...


But everything comes out to 0.05 ohms or maybe 0.046....

That is "60 times" better than a regular spark gap. HAHAHAHahahahaha!!!!!! Gerry, the gap resistance number is now 0.05 ohms...

The new schematic is here:


The IRGPS60B120KDP is a very impressive IGBT!!!!!! It has "more active area than a cow"... and "costs" more than a "cow" too $:O I expect them to be hard to get if history holds... DigiKey had 50 on the self for months.... In the last day... They got 12 left >>:o))) Thank goodness I got "mine" ordered five minutes before I posted this >>:o)))) After the Panasonic and CE cap thing, "I" know that game ;-))

The SISG does not "quench" (yet...) but with 0.05 ohms of resistance, all the energy is "safe and sound" in the primary circuit ;-)))

I hope to get a full and high voltage SISG going "real soon" that can run almost any coil... You can tap the voltage you want in 900V increments...

Even "I" am "stunned" by all this...  Things really have "all changed now"...



BTW - It is all "Public Domain" with no string attached... So party hardy :-)))