Electronics > Projects, Designs, and Technical Stuff
tig microwelder feasible?
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jmelson:

--- Quote from: coppercone2 on October 17, 2018, 10:09:29 pm ---I want it good. I guess you would want a constant voltage power supply followed by some kind of modulatable current regulator. I think that would work best for a precise job.

I am not sure where the tricks are though. I never used a tig, I don't know how the arc strike works. Do you have a strike circuit consisting of a inductor and some kind of fast isolator switch

--- End quote ---
No, they have a Tesla coil that delivers HF signal to a series inductor in the main welding circuit.  So, the HF is added in series to the welding circuit.
The HF is REALLY strong, so strong you can actually weld tiny stuff with it - kinda sorta.  I have a huge Lincoln square wave TIG machine, VERY old-school, but it works very well down to a few Amps.

Jon
coppercone2:
Are you sure thats a good idea? The HF might cause punch through of the foil and I don't think the metalurgy is well defined for that sort of thing.

I thought by using a isolated arc start thats parallel you can figure out how to grow the minimum possible hot arc with the lowest voltages etc to really control the situation.

It also sounds like you need custom magentics for that design, I really don't wanna go there unless you can find problems with my idea (other then small price I don't care for a one off, unless its gonna save me like 1000$)

On the other hand it might be better if you don't need to swtich because it can be theoretically faster and be able to put less energy into the starting arc.

Do you have a circuit of your old welder?
coppercone2:
I assume it can be thought of as a magnetic pulse boot strap through a transformer?
coppercone2:
I don't know how I feel about boot strapping the entire precision circuit and power supply with a RF pulse.... it sounds kind of like a bad idea...
coppercone2:
I even thought to float the arc starter from the circuit entirely some how, with a separate ground..

and for the control loop, based on how the arc behaves, do you really want a constant current source? It seems like you would want some kind of PID-ish feedback or heuristics based on how the arc wisks around and shit.. don't know if you can fight the fluid/plasma dynamics that form as the metal is vaporized and oil deposites and burned off etc though. might be just too complicated to try to control.. but the thermal time constants seem much lower then with conventional welding because everything is thin and heat is drastically sucked away more on the XY axis rather then depth.  :-//
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