Wireless remote control for electric welder

Abstract

The position of the main rheostat on an arc welding machine determines the pre-set welding current. An operator, working at a location remote from the welding machine, carries a pen-type adjustable rheostat which carries calibrations indicative of various percentages of the pre-set welding current. There are no extra electrical connections, such as wires, between the remote rheostat and the welding machine. If the operator wishes to change the magnitude of the welding current, he need not return to the main rheostat at the welding machine, but instead merely sets the remote rheostat for the percentage of pre-set current desired, and inserts the remote rheostat between the electrode holder and the workpiece. The minimum resistance of the remote rheostat is sufficiently high to prevent an arc from being struck. A current transformer in the welding machine senses the output (calibrating) current flowing through the welding cable. A signal proportional to the desired welding current reference is compared with a stored value of the present welding current reference to produce a control signal which is fed to an up/down counter whose output is the stored welding current reference. The welding current reference is thus either increased or decreased until it reaches the value called for by the adjustable remote rheostat. After a few seconds, the operator removes the remote rheostat from the electrode holder, and the welding current reference will now be at the precise desired value to produce the desired welding current.