In the DC circuit of the transistor Welding power supply, high-power transistor groups are connected in series to obtain the welding machine with any type of external characteristics and stepless regulation of current and voltage, which is called transistor Welding power supply. It is an electronically controlled Welding power supply. Transistors act as "electronic switches" or "linear amplification regulators" in the main circuit, using "switching" or "analog" transistor groups and closed-loop feedback to control external characteristics and output current