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How to Check Transformer Voltage & Current: Identifying Output from Old Electrical Appliances

mateusz2015_5102 4740 7
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Treść została przetłumaczona polish » english Zobacz oryginalną wersję tematu
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  • #1 16886399
    mateusz2015_5102
    Pupil  
    Hello. I had a few transformers from old electrical appliances. How to check what voltage and current the transformer gives?
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  • #2 16886449
    Jawi_P
    Level 36  
    Find on the net after the markings.
    Connect and measure the voltage.
    Knowing the core cross-section and the diameter of the winding wires, it is possible to estimate the approximate power of the transformer.
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  • #3 16886474
    wada

    VIP Meritorious for electroda.pl  
    read what is written on it and look for information on this topic.
    in the absence, measure the resistance of the windings and where it is the highest, and you can see that this winding is more isolated from the others, it can be a 230V winding, then you can connect it in series with a 25W / 230V bulb.
    If the bulb does not shine, it is probably 90% of the mains winding and you can connect directly to the mains and measure the rest of the windings.

    And only then can you
    Jawi_P wrote:

    Knowing the core cross-section and the diameter of the winding wires, it is possible to estimate the approximate power of the transformer.

    Worse, if a transformer from tube devices is, the anode winding may have the highest resistance, or a speaker transformer.
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  • #4 16886551
    Jawi_P
    Level 36  
    wada wrote:
    Worse, if a transformer from tube devices is, the anode winding may have the highest resistance, or a speaker transformer.

    Well, you are right, but I bet that when the author asks the current and voltage of the transformer, he knows where he got them from and knows their purpose. And it doesn't have to be that way ...
    Well, I even assumed that he knows where the primary and where the secondary winding / windings were.
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  • #5 16886856
    mateusz2015_5102
    Pupil  
    I took out 2 transformers from old printers. I do not know the printer models, because the housings were thrown away some time ago.
  • #6 16889223
    mateusz2015_5102
    Pupil  
    I measured the transformer resistance on the side where it is connected to 230V. And it has 500.
    On the other side of the transformer (where a thin wire is wound) there was 0.7 ohms.
  • #7 16889336
    zybex
    Helpful for users  
    The 500 ? a bit strange. Too much resistance for me. You may have been wrong.

    mateusz2015_5102 wrote:
    .
    On the other side of the transformer (where a thin wire is wound) there was 0.7 ohms.

    It cannot be like that either. You write that where there is a thin wire there is only 0.7 ?. Such resistance is usually where the thick wire is wound, i.e. on the secondary.
  • #8 16891176
    _jta_
    Electronics specialist  
    500? is a reasonable resistance of the primary winding of a transformer with a power of about 5W. What is the core cross-section?
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Topic summary

To check the voltage and current output of transformers from old electrical appliances, users are advised to examine any markings on the transformers and measure the voltage directly. If markings are absent, measuring the resistance of the windings can help identify the primary and secondary windings. A higher resistance winding may indicate a 230V winding, which can be tested by connecting it in series with a bulb. If the bulb does not light, the winding is likely for mains voltage. Users should be cautious with transformers from tube devices, as the anode winding may have the highest resistance. One user reported measuring 500 ohms on the primary side and 0.7 ohms on the secondary, prompting discussions about the expected resistance values for transformers of different power ratings.
Summary generated by the language model.
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