Ignoramus18456 wrote:

I can control the period of TIME when voltage is positive, or
negative, as percentage of the cycle.

That's what I meant.


I cannot make the CURRENT or VOLTAGE on positive or negative different.

That's clear. But if you average the current flow (better to say
polarity) and do not have a 50:50 cylce, you will have a DC-offset.
Imagine having a 100:0 cyle. It would give you DC with one polarity (of
course).

You do have a H-bridge, I guess.


I don't know wether sophisticated AC-TIGs do it this way, but I would
try it this way. ... if I could not get my hands onto a TIG and connect
a scope to it for an easy verification.*)
Before you ask: No, I don't have one. Good AC-TIGs are to expensive for
me. So I don't have a TIG at all. But if your modifcation works, I'll
have to rethink that.

*) Oh, you should find information about this subject in good
theory-oriented welding books. I guess, they also do have pulsing. So
you will have to hook a uC to your whashing-machine ... err ... TIG.
:-))


Nick
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