50/60Hz Powerline Noise

Discussion in 'General Electronics Chat' started by shravanraghu, Oct 22, 2014.

  1. shravanraghu

    Thread Starter New Member

    Oct 22, 2014
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    Hello

    I am designing an external battery pack to power an ECG amplifier. The ECG amplifier does not have a notch filter and the adapter used to power it does not have a 'GND' pin. The same adapter is being used to recharge the external battery pack as well. So i still have the powerline noise and i have a possibility of removing the powerline (50/60Hz) noise in the external battery pack i am designing.

    The input for the external battery pack is 12V--4A so using a RC lowpass/notch filter to remove the noise would dissipate a lot of heat. I wanted to know if there is any special kind of ic/circuit to remove this powerline (50/60Hz) noise from the power supply. The 50/60Hz interference problem occurs from the AC mains whilst charging the battery pack and using the ECG simultaneously.

    Thank You
    Shravan Raghu
     
  2. Papabravo

    Expert

    Feb 24, 2006
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    1,790
    You could use common mode chokes on either the AC pair, or the DC output. Next would be a pi filter of one or more sections.
    An IC -- sorry I don't think that is going to happen for powerline applications.
     
  3. shravanraghu

    Thread Starter New Member

    Oct 22, 2014
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    Thanks for the reply. I was looking for a method to eliminate noise on the powerline DC output I get from my adapter because I cant modify my adapter. Do you know any method of eliminating noise on the powerline?
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    Filter the voltage going from the battery to the circuits instead.
     
  5. shravanraghu

    Thread Starter New Member

    Oct 22, 2014
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    The batteries voltage does not have the 50Hz noise. So I have no issues there. The issue is only when I charge my external battery pack and this external battery pack is connected to ECG simultaneously. As ECG is a biosignal it contains information at 50Hz which gets contaminated with powerline noise.
     
  6. Papabravo

    Expert

    Feb 24, 2006
    10,142
    1,790
    But the noise has to get from the charger to the circuits. Put the filter on your device and the battery won't even know, or care, that it is there.
     
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