An electric arc welder for creating an arc welding process between an electrode and a workpiece where the welder comprises a preregulator having a first DC signal as an input and a regulated second DC signal as an output, an unregulated isolation inverter to convert the regulated second DC signal into a DC power signal and a weld control stage for converting the DC power signal into a welding signal. A controller causes the weld control stage to conform the welding signal into a waveform to provide welding process between the electrode and the workpiece, which controller has an output control signal regulated to produce a selected waveform or waveforms and the polarity of the waveform or waveforms. A device selects one of several stored welding processes as a program and a corresponding polarity for outputting by the controller.