Transformer enameled vs bare wire

Discussion in 'General Electronics Chat' started by bootlegengineer, Jul 12, 2017.

  1. bootlegengineer

    Thread Starter Member

    Dec 5, 2016
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    So I'm trying to rewind a transformer and I was wondering what would happen if I were to wind four strands of enameled copper wire together, soldered them together at each end and use that as the winding for my transformer instead of 4 strands of bare wire, in which they all touch throughout the strand, forming one wire?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    17,915
    5,477
    Never use bare conductor.:eek:
    In a pinch the four could be covered with heat-shrink tubing.
    Max.
     
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  3. bootlegengineer

    Thread Starter Member

    Dec 5, 2016
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    Lol I know. I would have wrapped it in some kind of insulator first. I'm just curious as to how not having each thread connect except at the ends would change the way the transformer works. I'm guessing that the number of turns would just be quadrupled but I could be wrong.
     
  4. MaxHeadRoom

    Expert

    Jul 18, 2013
    17,915
    5,477
    No: Equivalent to one conductor.
    Max.
     
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  5. crutschow

    Expert

    Mar 14, 2008
    22,025
    6,371
    Your combined wires act the same as a single stranded wire would.
     
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  6. Ramussons

    Well-Known Member

    May 3, 2013
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    As long as the frequencies being handled is low. At high frequencies, the "skin" effect plays a vital part. Multi strand wires, each insulated from each other, twisted as a single wire is more commonly used in RF transformers.
     
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  7. profbuxton

    Active Member

    Feb 21, 2014
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    That multi stranded separately insulated wire for Rf TXs is called "Litz" wire if I recall correctly.
     
  8. MrAl

    AAC Fanatic!

    Jun 17, 2014
    5,936
    1,277

    Hello,

    It depends which ends of the wire you solder together.

    In transformer construction terminology, when you wind one turn or several turns of wire around a core bobbin the end you lay down first is called the "start", and the end you lay down last is called the "finish".

    If you hold two lengths of equal length wire in hand and wrap them around the bobbin at the same time, that means you have two 'starts' and two 'finishes'. That would also be called a bifilar winding.
    If you hold three lengths in hand and wind them around the bobbin that would be trifilar.
    If you do four at a time that might be called quadfilar but you get the picture.

    Doing two in hand at the same time (bifilar) means you have two ways to connect:
    1. Connect the start of each wire together and the finish of each wire together.
    2. Connect the start of one to the finish of the other.
    3. You dont connect any ends.

    In case 1 you have only one winding with N turns. The current handling is roughly double one wire.
    In case 2 you have one winding with 2N turns. The current handling is the same as one wire, but the voltage doubles.
    In case 3 you have two isolated windings, but only isolated due to the wire insulation itself which is not considered high enough class for consumer safety and would not pass the "double isolation" standard.

    So you see the way you connect the ends makes a big difference.

    If you have three wires, then either the current goes up by three times or the voltage triples.

    If you have four wires, then you have some different ways of doing the ends:
    1. Connect four starts together and four finishes together. The pushes the current capability up four times.
    2. Connect two starts and two ends of two pairs, then connect the two pairs in series aiding. That doubles both the current and the voltage.
    3. Connect the start of each wire to the finish of each next wire, that pushes the voltage up by four times.

    So you have more options with four wires in hand. You could also later change it so that you use the windings independently forming four isolated windings.

    You always need insulation of the wire. It may or may not be actual enamel but may be another higher temperature material.
     
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