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  1. #1
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    Rewinding toroidal transformer

    Hello, I had a toroidal transformer with 200VA power and 2x17Vac secondary. I needed a 30Vac secondary so I started to take off a few turns until the voltage of the 2 serial secondaries was at about 30Vac. After making this modification, I needed a 24Vac output, so I started again to reduce the voltage, using the same method, by removing turns, until I have got 24Vac. After this, I put back the wire until I got a 30Vac secondary, as it was initially, but now I also had 24Vac secondary and the 30Vac secondary.
    So now, my transformer looks strange, but it works.
    Now I want to use it at a power supply which needs 30Vac transformer and one 17V secondary.
    The schematic of the transformer looks like this:
    Click image for larger version. 

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    And in the reality it looks like this:
    the 2 red wires on the left are for the primary (230V) and the 3 red wire and the rest of the wires are the secondaries.


    What would be the problems if I will continue to use the transformer as it is ?
    I know that there will be a inequality between the windings, but I don't know to what will lead this inequality ?

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  2. #2
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    Re: Rewinding toroidal transformer

    As long as the total load stays within 200VA, you should be fine.

    The problem with your question is that I cannot answer because I do not know the load currents.

    For example, you may have problem if you want to connect a 200VA load to the 17V output (there will be lot of IR drop).

    I would have cut the wire and made them independent windings so that you shall have more options.



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  3. #3
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    Re: Rewinding toroidal transformer

    Quote Originally Posted by c_mitra View Post
    The problem with your question is that I cannot answer because I do not know the load currents.
    The maximum load current from the 30Vac secondary will be 3A and from the 17Vac secondary will be about 0.8A.
    I will use the power supply to power resistive loads and inductive loads (motors).
    On the 17Vac secondary, will be connected 3 x 12V 80mm fans.



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