two output lines and two inductances that are magnetically coupled or a common mode inductance in the output lines the inductances may be installed when the power supply is built or added afterwards the inductance may protect the welding type power supply from high frequency noise on a workpiece application_number US 42839103 A description while the present invention will be illustrated with reference to particular components it should be understood at the outset that the welding type power supply and noise protection described herein may also be implemented with other components generally the present invention provides a way to eliminate or reduce emi using high impedance to the noise signal at some or all inputs and or outputs the most challenging input output lines are the primary power leads and the output welding leads which can carry hundreds of amps specifically in accordance with the preferred embodiment inductances are provided before or after bypass capacitors on the output lines the inductance are preferably a common mode inductor which is designed to have a large impedance at frequencies common to emi in the welding environment such as from two to twenty megahertz with lesser frequency components well into the hundreds of megahertz range the preferred embodiment is implemented on a welding type power supply using a topology such as that described in u s pat no 6 329 636 issued dec 11 2001 entitled method and apparatus for receiving a universal input voltage in a welding plasma or heating power source and a control scheme such as that shown in u s pat no 6 087 626 issued jul 11 2000 entitled method and apparatus for welding both of which are hereby incorporated by reference however the particular topology and control is not important to the invention.