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Solid State Disruptive Coil Spark Gaps

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Terry Fritz

Thu May 04 2006, 05:52AM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

I think I "did something" today...

I have mentioned this on the pupman group so forgive the cross post thing... But I "think" this might be a "BIG thing"...

Background files are here:

Sidac-Gap-1.pdf

Sidac-Gap-2.pdf

I think I got the SOB working!!!!

http://www.pupman.com/.../msg00071.html

Cheers,

Terry

Bjørn

Thu May 04 2006, 06:21AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

Even if it should blow up at the first live test it is a significant development. The modules are simple enough that almost anyone can do their own tests.

Steve Ward

Thu May 04 2006, 08:24PM

Registered Member #146 Joined: Sun Feb 12 2006, 04:21AM
Location: Austin Tx
Posts: 1055

Neat idea Terry. The only issue i see is that it cant quench... im not sure how much of a drawback that is really going to be. Are you planning on firing it up with a Tesla coil soon?

Terry Fritz

Thu May 04 2006, 10:11PM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi Steve,

The latest report with all the circuit details is here:

It seems to be working perfectly!!

I was originally going to make a little Off-Line style coil that would be easy and simple but the SIDACs were too low of current (we really don't know "how much" current it takes to blow them

)) So I got to thinking about and IGBT assist and here I am...

I hope to get a little coil going soon (waiting on #40 wire

)

It cost about $16.30 per 900V section so it is kind of expensive for a hobby 15kV NST that might need 23 sections at $375!!! But that cost is trivial for say a museum or commercial coil system... LOTs of uses in spark gap replacemtn really. It can easily be adjusted to run those big IGBT bricks >:)))

But I am really thinking of OLTC, flyback, ignition coil, MOT, etc. systems that run at lower voltage but higher current. I seem to be going for smaller super simple coils these days that anyone can whip up and play with

) No, transformers or iron, no "real" brainy electronics... Just small simple and fun stuff :o)))

I forgot to mention it is all Public Domain... I don't do the patent mess

)) So party hardy...

I have no idea about the quench... However, I have a 30V power isolated supply on the gate circuit and a TO-92 transistor could drop that gate voltage like a rock, perhaps with just a little 555 timer added... A "quench circuit" would have to start up within say a microsecond and rip the voltage down after a certain time. The 100 ohm gate resistor allows the power supply to stay up through all that if it can setup really quick... Probably a simple circuit addition, but I have not thought about it at all...

Cheers,

Terry

Terry Fritz

Fri May 05 2006, 02:55AM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

I compared my new SIDAC / IGBT circuit to a bare SIDAC to see how the losses compared.

At low currents the SIDAC was not super lossy. However at high currents, the SIDAC was very lossy and probably would not work for a spark gap in a Tesla coil at all. I wrote up a little blurb here:

The bare SIDACs worked fine for my DF-SRSSTC trigger circuit and it seems to work ok in some low powered stuff. However, if you need to push over say 50 amps, you had better throwin in the IGBT thing

Cheers,

Terry

teravolt

Fri May 05 2006, 03:33AM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

like your circuit Terry. do you think this circuit could be usefull for clamping over voltages on mosfets? If the sidacs are replaced with transorbs do you think it could be used as a clamp

Part Scavenger

Fri May 05 2006, 04:09AM

Registered Member #79 Joined: Thu Feb 09 2006, 11:35AM
Location: Arkansas
Posts: 673

Man what a sweet idea! That's almost as efficient as Steve W's DRSSTCs! SSDCSGTC, that's a finger full. SSSGTC maybe?

Cool, cool, cool. Thanks for sharing Terry!

Desmogod

Fri May 05 2006, 04:34AM

Registered Member #139 Joined: Sat Feb 11 2006, 11:01AM
Location: Perth, Western Australia
Posts: 358

Didn't TDU experiment with something similiar? His SSSSSTC I believe.

Terry Fritz

Fri May 05 2006, 06:03AM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

like your circuit Terry. do you think this circuit could be usefull for clamping over voltages on mosfets? If the sidacs are replaced with transorbs do you think it could be used as a clamp

I don't know why not. It is fast and could clamp one heck of a lot of current. But you have to use SIDACs. Transorbs and such would turnoff too soon. You need the SIDACs to stay shorted for a long time even if the voltage drops.

Didn't TDU experiment with something similiar? His SSSSSTC I believe.

Yes. His stuff is here:

He said he was having problems with quenching, but that may also have been due to the SIDAC's poor high repetitive current losses. I am not sure about the quenching yet.

I am trying to figure out how to make a coil with it now out of all the stuff I have laying around. I had realy not planned any of this... Now I have to make yet another coil

That's almost as efficient as Steve W's DRSSTCs!

It is actually more efficient than just shorting the gap with a wire too!!

Cheers,

Terry

Bert

Fri May 05 2006, 01:02PM

Registered Member #118 Joined: Fri Feb 10 2006, 05:35AM
Location: Woodridge, Illinois, USA
Posts: 72

Great work Terry!

I suspect the circuit can easily be made to quench by using a triggerable IGBT stage at the base of the stack. By removing the triggering signal at the first or second notch, energy transfer back to the primary cap should be virtually inhibited (except for small transformer action back through the free-wheeling diodes).

BTW, you may also need to add voltage equilizing resistors across the IGBT's when cascading them.

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