how to connect layers of transformer windings?

Discussion in 'General Electronics Chat' started by takao21203, Jul 5, 2012.

  1. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
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    When I connected this flyback power supply,
    the chip emitted an arc, the optocoupler still blackened.
    Strangely it survived, while the LNK363 broke into two pieces.

    I don't know what I have done wrong.
    Maybe the two primary windings (two layers) were connected in series in a wrong way?

    Or the chip's own power supply does not like the fact only having one rectifying diode.

    I only use one of the primary windings now. One layer fine wire! While the primary is one layer thick wire, It is visible in the picture. Between the layers, electrical tape is used for isolation.

    It works now!

    -Not a LED to mains, at least it is isolated.
    -Not transformerless, it is a full isolation transformer. I never built one until today. No calculations were made.

    But I am not sure how to connect the wires, if multiple layers are used. Isn't it true, one wire runs straight reverse, and then the second layer is added, having the same orientation? But then I don't understand why a large arc occured, and the chip was destroyed. It works fine now having only one layer.

    Maybe the small CFL coil I inlined was bad? There should be 1mH to filter EMI. And these coils have 2mH or the like.

    My question is mainly how to wind transformers, so it's independent from voltages.

    Also this is not meant to be for permanent use, not at all. I have placed it on the big transformer box because there are no clean surfaces nowhere, and pieces of metal on the floor. There is no correlation intended. But isn't it boring only to read some question and not to see the subject in question?
     
  2. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
    3,577
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    Maybe because I did not include a second capacitor after the EMI filter coil, so effectively, in series with the transformer coil. I just noticed. Using the schematic from LNK363 datasheet.
     
  3. szhighstar

    New Member

    Jun 26, 2012
    27
    5
    if there are two layers or more layers about primary winding, advise to add a layer of polyester tape between every layer, if winding pass high voltage, you should be use safety wire, because wire and wire is easy to short when transformer is working.
     
  4. takao21203

    Thread Starter Distinguished Member

    Apr 28, 2012
    3,577
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    1. yes all layers are isolated using thick electrical tape. PVC.

    2. Ordinary magnet wire, it is intended for the purpose to wind coils, motors and transformers.

    But how can I connect two layers?
     
  5. szhighstar

    New Member

    Jun 26, 2012
    27
    5
    Hi friend, I do not full understand your meaning, if it is a winding, after you finish a layer, then add a layer of tape, follow to wound other layer, if they are not same winding, you can use common pin on bobbin, end wire of a winding is connected on the pin, starting wire of other winding is connected on the pin, then cut off the 2/3 common pin, when we wound using sandwich, pirmary winding is separated to wound, we ofter select the method.
     
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