The aim of this thesis is to evaluate the influence of different operating modes of the EWM TETRIX XQ 230 AC/DC TIG welding power source and their parameters on the dimensions of welds. Welding was performed with mechanized cold wire feeding. The welding torch was mechanically driven using a welding tractor. Before performing the experiment itself, the wire feeder was completed, the control electronics were manufactured and the software was programmed. During welding an oscilloscope was used to measure the voltage and current of the arc. First, the alternating current parameters were evaluated. The base material used was a 4 mm sheet of EN AW 5454 H24 aluminum alloy. Some results were contradicting the statements in the welder’s operating manual. For example, it was found that the shape of the current waveform has little influence on the weld dimensions. After that, direct current welding was performed. In this part, 6 mm sheet of X5CrNi18-10 steel was used as base material. When welding with direct current, focus was on the pulse welding abilities of the power source, especially the frequency, which can be set up to 20 kHz. That being said, this high of a frequency did not bring any benefits and especially in the case of long pulses, the weld was practically identical to the one made without pulse.