Are DC arc welders filtered, or only rectified?

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A question for those who are technically inclined welding folks:  Are the outputs of a DC stick, TIG, and MIG welder a pulsating DC (i.e., rectified only, no filtering), or is the output filtered by an inductor/capacitor into a steady DC (i.e., like the output of a battery)?Thanks! -Bill
Reply:DC stick has no filtering.Mig has an in inductor and capacitor.Tig can be a lot of things.
Reply:all of my machines have a choke and or capacitors to smooth out the DC arc.    having just replaced a choke on my ranger 8 that shorted to the housing I can tell you there is a big difference in the smoothness of the arc with a damaged vs good choke on the DC current...Tiger Sales:  AHP Distributor    www.tigersalesco.comAHP200x; AHP 160ST; MM350P,  Spoolmatic 30A; Everlast PowerTig 185; Thermal Dynamics 60i plasma.  For Sale:  Cobra Mig 250 w/ Push-pull gun.  Lincoln Wirematic 250
Reply:My thunderbolt has some sort of an inductor after the rectifier.Parts list calls it  a "stabilizer".I don't know what it's purpose is, but I'm thinking it might smooth out pulsating D.C.Miller a/c-d/c Thunderbolt XLMillermatic 180 Purox O/ASmith Littletorch O/AHobart Champion Elite
Reply:Originally Posted by BillCalleyAre the outputs of a DC stick, TIG, and MIG welder a pulsating DC (i.e., rectified only, no filtering), or is the output filtered by an inductor/capacitor into a steady DC (i.e., like the output of a battery)?
Reply:Hi Bill, several scope traces below,This is a late 80s' inverter at idle set for stick (constant current), these machine fire high voltage spikes at a transformer. They have very little conditioning downstream and this lets the computer react to conditions and change pulse width rapidly.Below is a Thermal Arc Fabricator 250 tapped transformer mig. The redline shows a steady trace like a battery. As stated above by Rick, a choke and capacitance is used to provide a constant voltage.Below are first AC, then DC traces from a Lincoln Squarewave 275 at idle set for stick welding, The AC has no filtering at all showing about 60-65Volts, The DC trace is also 60-65Volts but pulses 120 times a second. I have never tested this under a load to see how close the DC comes to zero volts while welding.The last trace is a Lincoln Powermig 300 (chopper type power supply) set for Constant Current. This machine pulses a choke with 70Volts DC at 20khz. The Voltage never collapses below about 16Volts.Clear as mud right???Matt
Reply:Thanks guys -- great info!  And very good stuff Matt and Rick; I too should have thought to run the arc waveforms through a scope.    Just out of curiosity's sake, I think I'll use my old 10MHz analog o'scope to do it!-Bill
Reply:LOL Bill, the first time I scoped an inverter (with a 20Mhz HP) the freaking screen turned white??? WTF, I thought I broke it...Matt
Reply:Thanks for the scope pics!