A welder with an AC/DC output, whether its an electric arc machine like Miller's Thunderbolt or a gas engine drive like Miller's Bobcat.

DC welding offers advantages over AC for most Stick applications, including: easier starts; fewer arc outages and sticking; less spatter/better looking welds; easier vertical up and overhead welding; easier to learn "how to weld" and a smoother arc. DC reverse polarity (electrode positive) provides about 10 percent more penetration at a given amperage than AC, while DC straight polarity (electrode negative) welds thinner metals better.