Determine which wire is which on this transformer

Discussion in 'Power Electronics' started by fred62, Jul 20, 2016.

  1. fred62

    Thread Starter New Member

    Mar 23, 2016
    5
    0
    Please take a look at this transformer. It was on a power supply board with the following information.

    115V 60Hz 0.4A
    Out
    +5V 2.0 A
    +12V 0.7A
    -12V 0.3A
    Which two output wires (A to F) should I use, if I want to get 12V AC with at least 2A out of this transformer ? (I don't need DC voltage)
    powerSupply.png
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,564
    2,379
    First measure which windings are connected or common resistance test, next simply power the primary and measure the AC outputs that had continuity between them.
    Max.
     
  3. hp1729

    Well-Known Member

    Nov 23, 2015
    1,964
    219
    I don't see a possibility of getting 12 V at 2 Amps out of that.
     
  4. SLK001

    Well-Known Member

    Nov 29, 2011
    821
    229
    I can't get +12V at 2 amps out of this transformer, since it is rated at +12V @0.7A. The wattage of the xformer right now is 22 watts - you want 24 watts. You will need a bigger transformer.
     
  5. fred62

    Thread Starter New Member

    Mar 23, 2016
    5
    0
    Thanx Max,
    I measured
    A-B 29.4V
    A-C 14 V
    E-F 12.6 V
    Is there a way to be sure which is going to give me 2 Amps ?
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
    10,564
    2,379
    Going by the apparent wire gauge, the size of the bridge rect and the large caps, I would say you should be plenty OK with 2a.
    The transformer looks capable of 50va.
    Max.
     
  7. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    784
    Use it and see if the magic smoke escapes..........................................

    One of the wire pairs looks to be bifilar wound - that winding is the highest current.
     
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