Abstract: A linear DC welder for enhanced welding capabilities comprises one or more active filtering circuits. The active filtering circuit(s) are capable of producing a variety of user-configurable and user-controllable custom waveforms for use in various welding applications. The custom waveforms may be created and combined via the use of overlay waveforms and, in at least some preferred embodiments of the present invention, include agitation waveforms. The overall operation of the welder, including the power supply and the active filtering circuit can be controlled via an integrated feedback cycle that provides for the monitoring and adjustment of multiple weld process parameters including volts, amps, power, resistance, and displacement. Additionally, a low current ignition (“LCI”) circuit may also be included to provide for additional welding options.