Transformer pinout /connection

Discussion in 'General Electronics Chat' started by spark8217, Feb 16, 2015.

  1. spark8217

    Thread Starter Member

    Aug 29, 2011
    64
    2
    Hi
    Can anyone lend a helping hand with the wiring/pin out on the attached pictures. I have carried out a internet based search to no avail.There are no markings on the transformer at all.

    Many Thanks
    spark 8217
     
  2. MrChips

    Moderator

    Oct 2, 2009
    12,436
    3,360
    There are a number of steps to take.
    You want to figure out if it is a choke, auto-transformer, power, audio or pulse transformer.

    Firstly, do a physical inspection and see if you can identify primary and secondary windings.
    Are the diameters of the windings the same?

    Next get out your ohm meter and measure DC resistance between all pairs of wires. That will provide a lot of clues to the type of transformer.
     
  3. spark8217

    Thread Starter Member

    Aug 29, 2011
    64
    2
    Hi
    The diameter of the wires are all the same.
    yellow - orange = 009 Mohm
    brown -orange =.065 Mohm
    orange -blue =.027 Mohm
    blue - brown = .027 Mohm
    is there a requirement to test the green/yellow wire ?
    Cheers
    Spark 8217
     
  4. MrChips

    Moderator

    Oct 2, 2009
    12,436
    3,360
    Measure the resistance between one wire and all the others, including the green/yellow wire.
     
  5. panic mode

    Senior Member

    Oct 10, 2011
    1,320
    304
    MegaOhms?
     
  6. spark8217

    Thread Starter Member

    Aug 29, 2011
    64
    2
    The diameter of the wires are all the same.
    brown-orange = 25 Kohm
    brown -blue =12.7 Kohm
    brown -green/yellow = OL
    orange - brown = 0.18 Kohm
    orange - blue = 120 Ohm
    orange - green/yellow = OL
    blue - green/yellow = OL
    Cheers
    Spark 8217
     
  7. panic mode

    Senior Member

    Oct 10, 2011
    1,320
    304
    what is the size of the transformer? judging by the picture this is a small stepdown isolation transformer as found in many electronic devices.

    wires you see are just terminals (not the enameled magnet wire) so you cannot use that as a reference. you may take a look at wire through slots, normally primary will have a lot of turns of thin wire, then there will be separation layer, then secondary using thicker wire and fewer turns.

    I would start by checking continuity to determine connection diagram, then measuring resistance at lowest usable Ohms range (so you still get reading on the multimeter) until pair of terminals with greatest resistance is identified. that should be primary.

    chances are primary is two wires on one side (yellow-red), secondary is split (center-tap) which is other three wires (blue, orange, brown) and yellow-green is GND.

    power of the transformer can be estimated by computing size of cross-section of the iron core in center (around which wires are wound).

    then connect all wires to terminal strip(s) - don't want any wire moving when powering up!!! ("lusterklemme" or whatever...). next I would use another low voltage transformer (6 or 12VAC or similar) as a source of low voltage to power this 'suspected primary' and measure voltage across all windings. this way you can determine ratio of the transformer. for example if your AC line voltage is 120VAC and transformer output is 12V, we are looking at 10:1 ratio. but here we test with different primary voltage (say 9V) so if you measure 0.9V across secondary ratio is still 10:1.

    finally, I would do careful powerup test (safety glasses and preferably stay far enough when doing so, extension cord can be handy), at first brief, if ok then longer. if no smoke, measure output voltage.
     
  8. panic mode

    Senior Member

    Oct 10, 2011
    1,320
    304
    you posted while I was typing....

    if that is indeed power transformer, that configuration suggests that winding with three-wires is the primary, where wires are:
    orange - 230VAC (phase for EU market)
    blue - 115VAC (phase for NA market)
    brown - 0VAC (neutral)
    yellow/green - GND

    the two wires on the other side are single secondary (orange - blue).

    unused primary wire must be insulated and left unused (if you are in Europe, do not use blue, if you are in US/Canada, do not use orange).
    looks like you got yourself small transformer. still, be careful with testing....
     
    spark8217 likes this.
  9. spark8217

    Thread Starter Member

    Aug 29, 2011
    64
    2
    Thanks Panic-mode
    That would of been my thoughts too ! i will give it a try !

    Many Thanks
    Spark8217
     
  10. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    If you connect it to the mains power, place a small incandescent bulb (such as a 5w nightlight) in series with the transformer.
    That will prevent you from zapping anything if you have an incorrect connection.
    The correct connection will leave the lamp dark or only with a small glow.
     
    spark8217 likes this.
  11. spark8217

    Thread Starter Member

    Aug 29, 2011
    64
    2
    Hi All
    The transformer worked ! with the wiring configuration to the above description that panic - mode stated . !
     
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