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PLL driver with current xformer

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Tom540

Sun Dec 23 2007, 03:51PM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
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Posts: 617

60 turns is fine and like Steve said you don't need the inverters just a cap and diodes.

Linas

Fri Dec 28 2007, 11:21AM

Registered Member #1143 Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721

so, is it good driver ? or Use DWSSTC PLL driver,

Steve Conner

Fri Dec 28 2007, 12:37PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Huh, whose schematic is that? Steve Ward's? I've never seen it before

Linas

Fri Dec 28 2007, 12:49PM

Registered Member #1143 Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721

so, wich is beter ?

Marko

Fri Dec 28 2007, 12:54PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

It appears steve, I think it's also on his site but not linked, he gave links in some forum threads but refused to put on his site.
It's about his big multi-kW SSTC.

Now I lost them again, should have bookmarked or something :(

Linas

Fri Dec 28 2007, 01:23PM

Registered Member #1143 Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721

And Steve circuit have Interupter imput

, it's posible easy to make DRSSTC

and SSTC

Tom540

Fri Dec 28 2007, 03:13PM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
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Steve Conner wrote ...

Huh, whose schematic is that? Steve Ward's? I've never seen it before

Yep, Its a Steve Ward schematic and look what it says: an "improved version" of your PLL driver. He didn't want you to see it.

Linas

Fri Dec 28 2007, 04:04PM

Registered Member #1143 Joined: Sun Nov 25 2007, 04:55PM
Location: Vilnius, Lithuania
Posts: 721

it means that this circuit don't have mistakes and work properly ?

Steve Ward

Fri Dec 28 2007, 09:28PM

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

Free of mistakes? If i drew it right :P.

The only "advantage" to my PLL circuit was that it used the phase comparator 2, which as i recall naturally tries to keep a 0* lock instead of 90* like PC1. The trouble i had with Conner's original PLL driver (i havent tried anything newer than his "dirty weekend" driver) was that it seemed unstable when i was close to getting the phase set properly (because it was at the edge of the +/- 90* locking range). So i created this beast of a circuit and even implemented the 4066 switches to keep the thing from losing its place between interrupter firings. BUT, something is still a little leaky, so if you let it sit dormant for too long, the PLL does eventually lose its place (the voltage at VCO IN starts to drop) and it has to start all over again (which takes many RF cycles). Also, R4 and C6 are a bit on the large side, which is OK for SSTCs, but probably worthless for a DRSSTC.

The main key to the circuit is the 2 inverter gates and RC used to emulate the gate driver + mosfet switching delays that you are trying to compensate for. So you have to tune in the RC delay circuit to adjust the phase. But, this cheesy circuit doesnt exactly match the delay on the rising edge vs the delay on the falling edge, so the result is less than perfect, but it was "good enough" for me making sparks.

I guess i never posted the SSTC on my site because i didnt want a bunch of questions about the PLL circuit. The reason being is that its difficult to set up this PLL circuit properly unless you already sort of know how it works (in which case, you dont need to ask me). And when people ask me how the PLL works, i just keep telling them to read the datasheet, because thats how i learned about what they really do :P. I still think using a PLL here is kind of kludgey but does seem to work excellent for my SSTC now that its set up how i like. And to be honest, the PLL really *doesnt* help the zero-current switching issue! Remember all that talk about magnetizing current... well that pretty much prevents good ZCS on my coil. But, i dont care because the MOSFETS tough it out. What the PLL really does offer is a VCO to run off of when the feedback turns to garbage during ground strikes, and that is the main reason i used it (thats also the reason for the fairly large time constant on the VCO input). SSTCs are so much more fun when you can pull a fat yellow arc off the side of the toroid

. When this things sucking down 7kW, its even more fun.

Oh and the other reason i havent posted it publicly is that i forgot my website account password and have been too lazy to email Chris about it.

For those who are interested:

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