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Power Noise Filter question

Discussion in 'Electronic Basics' started by VXXV, Jan 25, 2005.

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  1. VXXV

    VXXV Guest

    Hi,

    do anyone knows how does the Power Noisy Filter work?
    And where can find such of information for my research?

    Thank You
     
  2. Line noise filters place an impedance mismatch between the line and
    the device, so that noise tends to reflect off it rather than pass
    through.

    A good source of typical design info is in the datasheets for actual
    prepackaged filters. Simulating those designs in Spice will
    demonstrate what is going on inside those designs. If the data sheets
    do not have values, you may have to take a few filters apart and
    measure the component values. The inductors shown with a circular two
    ended arrow inside are transformers with two tightly coupled
    windings. These can have high inductance (no gaps in the core) for
    common mode noise currents (going the same way in each line) because
    the differential currents (the normal current that comes in one line
    goes through the load and goes back out the other line) produce
    canceling magnetic fields that do not magnetize the core. These, of
    course present little impedance in the way of normal load current
    harmonics.

    see:
    http://www.corcom.com/
    for example:
    http://www.corcom.com/pdf/rfi/B Series.PDF
    http://www.corcom.com/pdf/rfi/AQ Series.PDF
     
  3. VXXV

    VXXV Guest

    Thanks your reply !

    Why do I have such idea, because my friend (he interested in playing Hi-Fi)
    and tell me that there has a device for plug to home mains supply, It like a
    black box terminal) When use it , the sound become obviously quite.

    So, I am looking for detail for DIY such device and try in my Hi-Fi
    system...
    Did your post information is same theorey?

    Thank You
     
  4. Probably not. The noise filters I describe are intended to reduce
    radio frequency interference between nearby circuits operating from
    the same supply line. (For example, your computer can produce visible
    interference on a nearby television screen) Unless your friend is
    thinking about the sound from a radio receiver, I doubt that there is
    any noticeable audio effect in using such filters. There amy be cases
    of very poorly designed amplifiers having line frequency hum, but
    these filters will probably not cure that.
     
  5. VXXV

    VXXV Guest

    Thank you again , John !!
     
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