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Thread: OT- Help on simple full-wave rectifier circuit

  1. #1

    Default OT- Help on simple full-wave rectifier circuit

    I'm out of touch with electronics circuitry for 30+ years. Your help is appreciated.
    The charger for my power drill battery went kaput due to an open primary at the power transfomer.
    The ouput of the charger is at 18v DC 500mA non regulated. The rectfier is a simple full wave non-center tap.
    I intend to replace the transformer but cannot remember the formula to calculate the secondary ac output voltage.
    Can some electronics gurus help pls?
    TIA

  2. #2

    Default Re: OT- Help on simple full-wave rectifier circuit

    tin the ratio of the incoming AC voltage to stepdown AC voltage. 230V/18 which is approximately 12:1. so that is the transformer u'll need.

  3. #3

    Default Re: OT- Help on simple full-wave rectifier circuit

    Quote Originally Posted by user12343
    tin the ratio of the incoming AC voltage to stepdown AC voltage. 230V/18 which is approximately 12:1. so that is the transformer u'll need.

    Thanks a lot

  4. #4
    Senior Member
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    Default Re: OT- Help on simple full-wave rectifier circuit

    Hmm, assuming you are referring to 18VDC @ 500mA (after rectification via a full wave rectifier), the pre-rectification AC voltage will be 18V/1.414 = 12.72V. If you use a transformer with a 18V AC secondary, you'll end up with 18 x 1.414 = 25.452V which is probably too high.

    Regards
    CK

  5. #5

    Default Re: OT- Help on simple full-wave rectifier circuit

    Quote Originally Posted by ckiang
    Hmm, assuming you are referring to 18VDC @ 500mA (after rectification via a full wave rectifier), the pre-rectification AC voltage will be 18V/1.414 = 12.72V. If you use a transformer with a 18V AC secondary, you'll end up with 18 x 1.414 = 25.452V which is probably too high.

    Regards
    CK
    Your assumption is correct. Thanks very much for your help.

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