Mains rectifier

You're not going to weld well with 1.4W output :/

Plus set amplitude to 169, you're undervoltaging it

Even then it's 3.2W, try again

The most basic of DC welders take a high voltage, low amperage source, rectify it, then transform it to low voltage, high amperage, which is what welders need; not allot of volts, but lots and lots of current. Plus, for this kind of setup, you'll probably want at least 3-phase 240VAC (480 would make things easier). With a 3/32" E7018 rod at a typical 85 amps, you'll be looking for a voltage of 15-25V, with 17-19V being ideal. Of course, any good DC machine is constant current, and the voltage varies with many things like arc length, the type of rod, quality of the connections, etc. So, this circuit won't do the trick. Search the web for info and examples, and keep it at.

ETJAKEOC- I didn't even look at the output current. Oops. Tried to make input to simulate USA mains and figured I was starting with 15-20 Amps and going to 100 Amps with the turns ratio. Does EC's input use rms voltage or peak?

rbrtkurtz- I made several basic MOT stick welders that work fairly well. Some were 220 and one was 115. The small one would only do 1/16 rods but was useful for small jobs. I had always thought that a robust 4 diode bridge and smoothing cap would improve the performance, consistency and penetration. I got the voltage in range and smooth. Still not sure why output went so low but I don't know much about sizing caps.

The smoothing cap isn't needed. However a big ass inductor helps alot to establish and stabilize the arc.

Also the arc resistance is really low

Yep. Try less than an ohm, poetically much less. A big ol' choke on the positive side will help more than a cap will.

Thank you so much for the help. I'm still trying to figure out how to make EC mimic mains power at full 15-20 amp load.

Well that 300 ohm resistor won't help. It RESISTS the flow of current. ;)

OK, I have reduced the arc resistance to 100mOhms, increased the input ac to 169V, and played around with chokes between 500mH and 1H. But I can't get the output above around 400mV at 4 Amps. I'm stumped.

Look for my circuit "MOT DC Arc Welder". It's somewhere in the ballpark I think.