Transformer of Unknown Rating

Discussion in 'Datasheets, Schematics, Manuals and Parts' started by ag273n, Dec 26, 2016.

  1. ag273n

    ag273n

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    We had this old NM-CD AA, AAA, and 9V -All-In-One Battery Charger. Its very old and is currently not anymore working. I wanted to know the rating of the Transformer inside it so i can reuse it for future projects, BUT, there aren't any part numbers or anything written on this transformer.. so how do you find out a rating of a transformer if you only have as far as a multimeter and internet?...

    I'm sure this isn't a 220v-110v, but probably to lower voltages.

    DSC_2258.JPG DSC_2259.JPG DSC_2265.jpg

    The two blue thicker wires went straight to 220V AC mains on the charger's design. The PCB beside it was previously connected to it. It only had Resistors, Diodes, and LED's then straight to the AAA, AA, and 9V battery connection.
     
    ag273n, Dec 26, 2016
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  2. ag273n

    ag273n

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    I just did some tests... gladly i'm still alive, nothing burned

    Did some continuity tests first which seems ok, except for the blue thick wires which may not be beeping on the tester due to some reistance of the coils- not sure on this part...
    Connected the thick blue wires to the 220 ac mains with some aligator clips and hooked my multimeter to the thin wires taking extra caution my skin doesnt touch any of the wires and no short circuits, my results are below:

    Thin blue wire & thin black wire = 23V
    red & yellow = 7V
    Thin blue wire & red = 15V
     
    ag273n, Dec 26, 2016
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  3. ag273n

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    If you know the blue wires went to 220VAC then you could connect them to 220VAC (via a 15W light bulb) and carefully measure the voltage on the other windings.

    In this case carefully means you connect the meter to the leads before you apply power and you touch nothing while the power is applied.

    All of this assumes you have sufficient experience with mains wiring to do this safely.
     
    (*steve*), Dec 26, 2016
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  4. ag273n

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    And you beat me to it. Glad you're still alive :-D
     
    (*steve*), Dec 26, 2016
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  5. ag273n

    ag273n

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    This gives me confidence to test some other transformer i may meet in the future :)
    Sounds dangerous! I like it!
     
    ag273n, Dec 26, 2016
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  6. ag273n

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    In terms of power rating, it is pretty much field with weight. If you have a transformer rated at 100VA, then another with a similar weight will have a similar rating. If the are multiple windings you have to guess (possibly based on wire gauge) the split between them.
     
    (*steve*), Dec 26, 2016
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