Building a choke

Discussion in 'The Projects Forum' started by Rick A, Sep 29, 2011.

  1. Rick A

    Thread Starter Member

    Jul 30, 2010
    28
    1
    Hello, everyone; once again I need some advice.

    I'm trying to convert a 220 v, 60 hz AC welder to DC and need a choke to smooth out the rectified current (maybe 150 a. max at 50 v or so). I've read everything I can find on the web and the old threads here and still confused. I've seen suggested cores of air, steel bar, old laminated xmfr core, ferrite rods in a cardboard tube, iron filings, etc. and still don't know what would work best for this application. Also noticed solid copper wire is always recommended, but I happen to have some #4 multistrand and wonder why I couldn't use it. Thank you for any suggestions.

    Rick A
     
  2. wayneh

    Expert

    Sep 9, 2010
    12,123
    3,047
    I think we need more details on what you have, and what you want it to do. Post a diagram of your plan.

    As for the wire, any will work in theory. Coated copper gives the most efficient use of space and copper. It minimizes space occupied by the insulation and minimizes DC resistance. Also, heat dissipation is a factor; insulated wire would melt in many applications. I suppose capacitance is an issue at higher frequencies as well.
     
  3. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,172
    397
    If you used a 1000W microwave transformer core, ' could wind about 30 turns of # 4 insulated wire- depending on insulation. How much inductance?; how much is needed?
     
  4. Rick A

    Thread Starter Member

    Jul 30, 2010
    28
    1
    I've looked all over the web and not found a mH value for the inductor I need; finally occurred to me to look at the one in my mig welder. It's built on a laminated core, about 22 turns of square wire of about #4 wire. I happen to have an old microwave xmfr and think I'll follow your suggestion to use it. Thank you both for your inputs.

    Rick A
     
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