Coil as shunt??

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  • Behemot
    Badcaps Legend
    • Dec 2009
    • 4845
    • CZ
    #1

    Coil as shunt??

    I am quite often seeing two +12 V like-a-rails or also +,3,3/+5 V rails with coils instead of resistors shunts. There seems to actually be feedback from before and after the coils to monitoring IC.

    Can this work? If so, is it any precise or just so-so? Reason why I am asking is I always though the high-frequency AC ripple part of the DC will change the coils reactance so much effectively making it's useless as shunt (resistor) Or it does not?
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    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK
      #2
      Re: Coil as shunt??

      An inductor only attenuates AC current. However, most inductors are imperfect and have resistance. If wire length and resistivity is known then the current through the inductor can be measured. It means you don't need a shunt resistor.
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

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        • Behemot
          Badcaps Legend
          • Dec 2009
          • 4845
          • CZ
          #3
          Re: Coil as shunt??

          I know, but I mean, can it's apparent resistance change with ripple? Cause with usual wire, I guess not, but with the ferrite core which increases inductance by a great margin, I think there may be some changes. And as the resistance of shunts is usually at miliohm level, just a slight change can cause very different readings…
          Less jewellery, more gold into electrotech industry! Half of the computer problems is caused by bad contacts

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