D.C. arc welder with solid state components

A.D.C. arc welder with solid state components, having two output terminals and means for generating an arc at said output terminals, said means including means for providing a direct current, a first electric path downstream of said direct current providing means, a transformer having a primary in series with said first electric path and a secondary connected to said output terminals through a second electric path, electronic switching means for causing a pulse train to be generated in said first electric path and in said primary, means for controlling said electronic switching means according to the tension and current conditions at said output terminals, and means for converting the pulse tension signal induced at said secondary by said pulse train in said primary into an unidirectional current signal, wherein said electronic switching means includes a first and a second controlled diode serially connected in said first electric path, one of said controlled diodes being connected upstream and the other downstream of said primary, a further controlled diode and a capacitor connected in series with respect to one another and in parallel with respect to said primary between said primary and said first and second controlled diodes, respectively, an inductance in series with said capacitor and in parallel with said further controlled diode, and wherein said means for controlling said electronic switching means includes a square wave generator providing a half-wave tension signal for simultaneously triggering said first and second controlled diode to become conductive and a half-wave tension signal for triggering said further controlled diode to become conductive, the triggering of said further controlled diode causing said first and said second controlled diodes to be turned off into the non-conductive state, said square wave generator generating a square wave having a period depending on the voltage and current at said output terminals.