Can I use a stock SIGNAL GENERATOR to drive an H bridge?

My objective is to make a square wave inverter for high amperage DC for TIG welding, from a 300A CC DC welding power supply.
I would actually be content with 200A current. AC would be used for aluminum only.
I own a Wavetek 171 signal generator:
http://www.labx.com/v2/spiderdealer2/vistaSearchDetails.cfm?LVid '79965
Can I simply use it to drive either MOSFETs or IGBT's that make up the H bridge?
i
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My objective is to make a square wave inverter for high amperage DC for TIG welding, from a 300A CC DC welding power supply.
I would actually be content with 200A current. AC would be used for aluminum only.
I own a Wavetek 171 signal generator:
http://www.labx.com/v2/spiderdealer2/vistaSearchDetails.cfm?LVid '79965
It can do up to 10 volts, supposedly, and any frequency.
Can I simply use it to drive either MOSFETs or IGBT's that make up the H bridge?
thanks
i
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Ignoramus965 wrote:

Not directly.
You'll need some level translation.
If you don't know what that means then you shouldn't be attempting to make a welder.
Unless you fancy welding *yourself* to something ? Terminally maybe ?
Btw - electronics hobbyists are advised to try out *low current* stuff before progressing to the 'arcs and sparks' scenario !
Graham
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On Fri, 09 Sep 2005 04:34:10 +0100, Pooh Bear

do you refer to signal voltage level?

I would love to hear you share your knowledge.
i

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Ignoramus965 wrote:

Google IR2011.
That'll explain driving H bridges a bit. Be especially aware of the term 'high side drive'.
Graham
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On Fri, 09 Sep 2005 05:07:38 +0100, Pooh Bear

Thanks. I just read their spec sheet. Is there some other document that you have in mind?
i
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Ignoramus965 wrote:

I can think of loads ! You can't imagine how many data sources I used before venturing into this arena.
You need to examine the application notes really.
The ANs normally contain 'nuggets of wisdom' worth as much or more than gold.
Graham
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On Fri, 09 Sep 2005 05:32:36 +0100, Pooh Bear

Thanks. I will read them closely tomorrow, when I print that document out.
That said, can I get some intro on how these chips are used? Are they connected to DC power (for sending signals to MOSFETs), as well as to a signal generator that "drives" the chip? How do I tell the chip what to do?
Is that big enough for a 12 kW power transmission device, or is it just an example?
I apologize if this question is answered in application notes.
i
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Ignoramus965 wrote:

So many issues !
When you've read a few ANs about gate drivers pop back in and ask again.
Ohh - and you do know about how to control circulating currents in pcbs ?
Graham
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On Fri, 09 Sep 2005 06:05:45 +0100, Pooh Bear

Thanks. I will spend quite a while reading that stuff. That said, all I find are spec sheets. Is there some secret location for application notes, say for the IR 2113 driver?
i
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scratch that, I found something
http://www.irf.com/technical-info/appnotes/an-978.pdf
i
wrote:

--


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Ignoramus965 wrote:

That's a very good app note indeed.
For your application you should perhaps be thinking about a high side auxiliary supply. Prolly a 555 would do the job.
Graham
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Ignoramus965 wrote:

Look Sonny ! All the semi makers write app notes about how to use their products best so that they can hopefully sell more of them !
I have no trouble finding the ANs. Why do you ?
Try 'navigating the site' ! Most sites have their own search facility.
OTOH if you don't know how to use the internet as a search tool......
Graham
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On Fri, 09 Sep 2005 05:07:38 +0100, the renowned Pooh Bear

Better read the application notes really carefully too. What you don't know will fry expensive semiconductors, typically a few at a time.
Best regards, Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
snipped-for-privacy@interlog.com Info for manufacturers: http://www.trexon.com
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Spehro Pefhany wrote:

Trouble is....
Even when you do know it, you're likely to fry several by accident for good measure anyway !
Fzzztttzzzzzzttt ! poPPPP ! BANG !!
Graham ;-)
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On Fri, 09 Sep 2005 05:56:24 +0100, the renowned Pooh Bear

Yup. ;-)
Best regards, Spehro Pefhany
--
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snipped-for-privacy@interlog.com Info for manufacturers: http://www.trexon.com
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Pooh Bear wrote:

I testify to that. I have even managed to make a plastic to-92 package explode. Driven a power FET into thermal runaway and destroy it. and fried more IC's with electrostatic damage than i could count.
--
JosephKK


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Pooh Bear wrote:

There's quite a bit of gate capacitance in larger MOSFETS that has to be quickly filled or emptied. Drivers are by no means trivial.
In fact, the design of the driver stage is usually much more difficult than the output stage.
--
Many thanks,

Don Lancaster
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Don, what are your thoughts on using IGBT's for switching?
i

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Ignoramus965 wrote:

Graham replies that they're very good these days.
Mosfets are best at the higher frequencies though.
IGBTs have their own little 'quirks'.
trouble is.... you really have to have been doing this stuff for ages to pick up the relevant issues. For a beginner, jumping in at the deep end involves a cliff-like learning curve.
Graham
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