Scored a welder. Is it any good?

[bobodu]

Thanks, that reminds me, I think I need to brush up on my sinusoidial waveforms to.

Didn't Captain Kirk battle them once??

 

[Transit]

Kebo, you have the right idea, but you're a little off the mark. 120 volt AC doesn't swing + and - 120 volts. That figure 120 volts should read 120 volts RMS [Root Mean Square].
Simply put, 120 V DC = 120 V RMS A-C. The light, heat and power that a 120 v DC source delivers are identical to a 120 V RMS source. However the peak value of a 120 v A-C is 1.414 x the RMS value of 120V, that is its 169.70562 volts, rounding off to 170 volts + and - peaks.