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Why Phone Charger Makes High Frequency Sound

  1. May 20, 2012 #1
    Hi. I noticed that my phone charger (output: 5V DC) makes a constant high pitched noise when plugged into the wall. It's not too loud but you can hear it when you are within maybe 4 ft of the charger. When I plug my phone in, it starts making intermittent noises. I was wondering what this could be caused by?
  2. jcsd
  3. May 20, 2012 #2
    Most charges are using switching regulators, they oscillates in 10s of KHz, you can hear it if the transformer buzzes.
  4. May 20, 2012 #3
    does that mean there is current flow and thus energy loss even without the phone attached?
  5. May 20, 2012 #4
    Yes, there is always a little loss if you keep the charger plugged in.
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