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Amperage in the secondary of a Transformer

Discussion in 'General Electronics Discussion' started by 200dB, Sep 22, 2009.

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  1. 200dB


    Sep 22, 2009
    Hi everyone,

    I recently received a Creative Labs T6100 from someone who returned from the U.K., less the power supply. The original power transformer stepped down from 220V to 13.5v @ 5A. My area is wired for 120V so I've been looking for a suitable replacement.

    My closest matches are a 12.6 vct @ 5A or a 25.2 vct @ 3A.

    I'd like to know what's the relationship between the amperage output and the end leads? Is the amperage split among them or would I get the full amperage from using just one lead?

    For instance:

    In the case of the 25.2 vct transformer, if I were to use just one lead connected to the CT would I get 12.6vac @ 3A, 12.6vac @1.5 amps or 12.6vac @ 6A?

    I'd appreciate any and all responses.
  2. 200dB


    Sep 22, 2009
    O.k. I finally found a site that explains it. Basically it'll be 1.5 A since each leg to CT will be using 1/2 of the winding material...:cool:
  3. Resqueline


    Jul 31, 2009
    Not quite correct. You can always get the specified amperage out of a transformer no matter how small portion of the secondary you use. With regards to the primary and the core you could draw twice the current from the secondary if you used only half of it, but that would require the secondary wire gauge to be twice as large as initially needed - which is unlikely.
    The other way to use the 25.2Vct transformer to the full (6A) is to connect the ct to negative and then rectify using only two diodes - one from either end. That way either side will be loaded only half of the time so they can be "overloaded".
    For the 12.6Vct you'd ignore the ct and hook the ends to a full bridge (4 diode) rectifier. You lose almost 1Vdc with this solution compared to the 2-diode setup.
    Last edited: Sep 23, 2009
  4. 200dB


    Sep 22, 2009
    Thanks for the response Resqueline.

    I should have mentioned that the T6100 was designed to accept 13.5 vac, so that external rectification isn't necessary. It's simply a matter of wiring the transformer for the appropriate voltage and maximum amperage...:cool:
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