convert ac 225 to dc

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Could any one tell me how to wire a rectifier bridge using stud mount rectifiers. I have six 70 amp stud mount rectifers  the markings on the side of the rectifiers show the arrow pointing down where it would bolt to the heat sink. I was wanting to use 2 heatsinks if possible.
Reply:All I can remember is it takes 4 diodes.  One side of the AC is hooked to one + and one - diode.  Same for the other side.  The diodes are tied together to get DC.  Its a full wave rectifier or Wheatstone bridge.  You can buy little ones at radio shack.  I use them to repair battery chargers.    top and bottom AC, left and right DC.Each diode will carry 1/2 the load, so don't exceed 140 amps.Do I make any sense?DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Really need a project?  How about just welding with AC or sell this and buy a nice little DC welder?  Just curious what your doing.
Reply:just trying to get dc output so i can burn diffrent typs of rods. I also thouht abougt making it a scratch start tig
Reply:I also thouht abougt making it a scratch start tig
Reply:I'm not saying I personally recommend you start screwing around with 220 and some diodes, but here is a diagram anyway of what the full wave bridge looks like:http://images.google.com/imgres?imgu...%3Den%26sa%3DGMake sure you get the diode directions correct or you'll have a nice dead short across your 220 lines. Zap Zowie and I don't mean the good welder Zap - John
Reply:*---!<---*---!<---**---!<---*---!<---*ac.........dc..........acHard to draw schematics with a type writer! Like trying to make an ac machine burn direct!City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:Runchman, thanks for the link.  That is what I was trying to say.  I worked with electric forklifts and the chargers for years.  If all the diodes are labeled the same, you will have to insulate the heat sinks.  Be creative.I would like to see a pic when its done.DavidReal world weldin.  When I grow up I want to be a tig weldor.
Reply:Zap Zowie and I don't mean the good welder Zap
Reply:The arrow points in the direction of current flow... Please note that depending on the type of diodes you have the heatsink WILL be hot, and I am not talking just heat but electrically live!  Also you need to figure out the peak to peak voltage you are rectifying and make sure you diodes are rated to handle it.And the only other thing I can think of is capacitors are commonly used to smooth out the remaining "humps" in the rectified output, they are not cheap, and BE CAREFUL! If you do put capacitors in use a beading resistorGood luck!
Reply:instead of caps, use a chunk of iron with several turns of wire wrapped around it... ( an inductor ) ... seen that done also.got a dead welder? im sure the transformer would make a great inductor till a reasonable substitute could be found
Reply:The better filters use capacitors and inductors.City of L.A. Structural; Manual & Semi-Automatic;"Surely there is a mine for silver, and a place where gold is refined. Iron is taken from the earth, and copper is smelted from ore."Job 28:1,2Lincoln, Miller, Victor & ISV BibleDanny
Reply:Its a fairly simple project.  You can buy the diodes from one of the online surplus sites.  You need to make sure they are rated, overrated is better, for the current you expect to draw and also for the peak voltage.  The output from the rectifier bridge is choppy so its best but not absolutely necessary to smooth it with a cap or a choke.  The cap(s) should have bleedoff resistors to let the charge leak away when the circuit is turned off, but for welding voltages this is not crucial.  Bleedoff resistors are crucial when the cap is charged up to a dangerous voltage.  The diodes will need to dump a lot of heat.  If they dont come with heatsinks then they need to be mounted on a piece of copper or al and there should be a fan moving air over them.  There used to be an outfit sold a box that did all of this for about $150 and IIRC all it had was four big diodes and a fan.If you know enough about electricity to understand a bridge rectifier its a simple project otherwise, you are better off trading your AC box for an AC/DC unitPS Just to be sure:  We are talking about rectifying the low voltage/ high current OUTPUT of the welder  and NOT the  highvoltage INPUT - that wont work and is quite a bit more dangerous too.Last edited by maddog; 08-08-2007 at 09:10 AM.355# Hay Budden3# Hofi HammerPropane ForgeIdealarc TIG 300/300AllStates Oxy Propane torchSmith Little Torch
Reply:thanks for the help with the rectifiers going to put it together this weekend.