Arc welding capable of multi-mode welding

摘要

An electric welding control circuit incorporates a mode selection switch to enable the welder to be used in a selected one of several operational modes, such as a rod welder, a MIG, a TIG or a spot/stitch welder. A wire feed motor is used in the MIG mode to feed welding wire to the electrodes. A regulating circuit controls the speed of the wire feed motor as a function of the welding electrode voltage. A zener diode in the regulating circuit turns on a switching transistor to cause the feed motor to run at a normal speed when the voltage is between predetermined limits and a second zener diode senses a loss of arc to slow the feed. In a spot/stitch mode, a timer is used to time the spot periods, the timer operation being dependent on the presence of an arc as detected by the regulating circuit so as to commence the timed period when the arc is struck.