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  1. #1
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    [SMPS]Flyback converter

    Good morning,
    Could anyone please clarify for me how this flyback circuit work?
    You'll find attached the circuit and the properties of the transformer TR1.
    Click image for larger version. 

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ID:	153440Click image for larger version. 

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ID:	153441

    P.S: this circuit convert 220V AC to 24V DC.

    Thank you.

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  2. #2
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    Re: [SMPS]Flyback converter

    Principle of flyback operation:

    1) Current goes through transformer primary.

    2) Flux field builds however no current flows in the secondary due to the diode preventing it.

    3) Current is shut off to the primary.

    4) Flux field collapses, sending current through secondary in direction permitted by diode.

    The neighboring circuitry is designed to cause On/Off switching at the proper times. Normally the output stage sends a feedback signal (via the optocoupler) so as to regulate duty cycle. The purpose is to regulate voltage at the load, although your schematic appears to lack a load.


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  3. #3
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    Re: [SMPS]Flyback converter

    there's a dot missing on the dwg ...



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  4. #4
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    Re: [SMPS]Flyback converter

    Thank you for your response, it was very helpful.
    Could you explain with more details the functioning of the transformer?
    Have a nice day.



  5. #5
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    Re: [SMPS]Flyback converter

    Schematic doesn't make sense to me. Q1 is supposed to control the base current of Q2 to provide regulation but it can't. The capacitor values look suspicious too. With D1 being a slow recovery device it implies low switching speed so the low value of C5 doesn't look realistic.

    Brian.
    PLEASE - no friends requests or private emails, I simply don't have time to reply to them all.
    It's better to share your questions and answers on Edaboard so we can all benefit from each others experiences.



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  6. #6
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    Re: [SMPS]Flyback converter

    it is not a completely thought out ( or verified by build and test ) circuit ...



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