1. We will be in Read Only mode (no new threads, replies, registration) for several hours as we migrate the forums to upgraded software.

Tapping a crude choke/inductor

Discussion in 'Power Electronics' started by Chefslot, Feb 19, 2019.

  1. Chefslot

    Thread Starter New Member

    Sep 24, 2018
    16
    1
    Is it possible to tap a inductor made from a microwave transformer? After the ac to dc rectification tapping the inductor at 4, 8, 10 turns will give me a more or less pulsed weld.
    Regards
     
  2. jpanhalt

    Expert

    Jan 18, 2008
    7,670
    1,874
    Are you talking about tapping the factory made primary or the homemade secondary? The former would be very difficult to impossible. The latter can be done quite easily . The MOT welder I made only had 6-1/2 turns. How many turns do you have in the secondary?

    Are you talking about current pulsing as is done in MIG? I pulsed mine using a SST and one shot timer.
     
    Chefslot likes this.
  3. Chefslot

    Thread Starter New Member

    Sep 24, 2018
    16
    1
    Thank you for your reply, both the primary and secondary will be removed to give me just a core, that will then have 12 or 10 turns to smooth out the amperage, I then wanted to tap that to adjust the smoothness of the DC signal.
    Regards
     
  4. jpanhalt

    Expert

    Jan 18, 2008
    7,670
    1,874
    I don't see why you cannot tap a winding that you are making. With magnet wire, I would just solder to it. With heavy gauge stranded wire, I would probably use a crimp fitting or a T-junction (e.g., effectively two windings). I have not done that, so that latter advice is not based on experience.
     
    Chefslot likes this.
  5. Chefslot

    Thread Starter New Member

    Sep 24, 2018
    16
    1
    Going to be using awg 2 wire around 250-300 anp so a crimp fitting might be a little difficult. Yes thinking solder a shrink tubing over. I think do the windings first as that may be the hard part. then hack into the side.

    When you wind something like this does it matter if the windings are like the //////// or XXXX

    Regards
     
  6. jpanhalt

    Expert

    Jan 18, 2008
    7,670
    1,874
    Actually I used #4 welding cable in my MOT. By "welding cable" I mean the heavy gauge, flexible cable with many small strands that are often composed of bundles. The problem with soldering welding cable is that the solder wicks quite a ways from the point of soldering. That can be a source of stress and break. For such cables, I believe crimping is the preferred method. Even if you bring the winding to a terminal, make the Y and return it, I don't believe the inductance will be much diffident than with a one-piece cable. At least, the equations I have seen for low frequencies only consider the number of turns.

    I am ignoring the effect of the winding at the splice being further from the core than the others.
     
    Chefslot likes this.
  7. Chefslot

    Thread Starter New Member

    Sep 24, 2018
    16
    1
    Good point about the weakest point I just can't imagine a terminal or crimp T / Y being bug enough.
     
  8. Chefslot

    Thread Starter New Member

    Sep 24, 2018
    16
    1
    [​IMG] [​IMG]
     
    jpanhalt likes this.
  9. jpanhalt

    Expert

    Jan 18, 2008
    7,670
    1,874
    @#8

    Yes, something like that is what I would do. When I wrote "crimp", I included screw tightened terminals in that class. The split bolt design you show has the advantage that the main wire is not interrupted.

    John
     
    Chefslot likes this.
  10. Chefslot

    Thread Starter New Member

    Sep 24, 2018
    16
    1
    I know i shouldnt say this, and it would be down to my own doings, but will the choke get hot enough to melt hot glue,, i'm thinking of a way to isolate them now?
    Regards
     
  11. jpanhalt

    Expert

    Jan 18, 2008
    7,670
    1,874
    Chefslot likes this.
Loading...