Stud welder control circuit

Claim 1

A STUD WELDING DEVICE COMPRISING: A STUD HOLDING AND RETRACTING MECHANISM ADAPTED TO SEQUENTIALLY POSITION A STUD AGAINST A WORK SURFACE TO WHICH THE STUD IS TO BE WELDED, TO THEREAFTER RETRACT THE STUD TO PRODUCE A PRE- AND DETERMINED GAP BETWEEN THE STUD AND WORK SURFACE, AND FINALLY TO RETURN THE STUD TO THE WELD POSITION ON THE WORK SURFACE, A SOURCE PROVIDING HALF CYCLES OF ALTERNATING POLARITY CURRENT, MEANS ENERGIZED BY THE SOURCE PROVIDING FULL WAVE DIRECT CURRENT TO A PILOT ARC CIRCUIT BETWEEN THE STUD AND WORK SURFACE, SAID PILOT ARC CIRCUIT CURRENT HAVING A LOW VALUE WHICH WILL PRODUCE A PILOT ARE ACROSS THE GAP AS THE STUD IS RETRACTED FROM THE WORK SURFACE, CIRCUIT ELEMENTS COMPRISING AN INDUCTANCE, A DIODE AND A UNIDIRECTIONAL CONDUCTING DEVICE HAVING A CONTROL ELECTRODE FOR SWITCHING THE DEVICE FROM A NONCONDUCTING TO A CONDUCTING STATE IN RESPONSE TO AN INPUT SIGNAL, A FIRST CIRCUIT CONNECTING THE STUD, THE WORK SURFACE, THE INDUCTANCE AND THE DEVICE IN SERIES ACROSS THE SOURCE, A SECOND CIRCUIT CONNECTING THE STUD, THE WORK SURFACE, THE INDUCTANCE AND THE DIODE IN A SERIES CIRCUIT AND CONTROL MEANS ADAPTED TO SUPPLY SIGNALS TO THE PIVOT ARC MEANS, THE STUD HOLDING AND RETRACTING MECHANISM AND THE CONTROL ELECTRODE FOR INTIATING THE PILOT ACR CURRENT AND RETRACTING THE STUD DURING PILOT ARC CURRENT FLOW FOR ESTABLISHING A PILOT ARC BETWEEN THE STUD AND WORK SURFACE, SUPPLYING INPUT SIGNALS TO THE CONTROL ELECTRODE DURING AT LEAST ONE HALF CYCLE CONCURRENTLY WITH THE PILOT ARC FOR EXTABLISHING A WELDING CURRENT FLOW THROUGH THE FIRST CIRCUIT AND SIMULTANEOUSLY STORING ELECTRICAL ENERGY IN THE INDUCTANCE, AND FINALLY TERMINATING THE INPUT SIGNALS AND RETURNING THE STUD TO THE WELD POSITION DURING SAID ONE HALF CYCLE FOR RELEASING THE ELECTRICAL ENERGY STORED IN THE INDUCTANCE THROUGH THE SECOND CIRCUIT TO PROVIDE A CURRENT FLOW BETWEEN THE STUD AND WORK SURFACE WHEN THE STUD IS IN THE WELD POSITION FOR A TIME INTERVAL SUBSEQUENT TO THE TERMINATION OF CURRENT FLOW