Question about Homedics iSoundSpa Max Clock Radio with Docking Station for Apple iPod

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Humming noise Hi, this is the second one in two years. First, just quit, but this one has a persistent humming noise when not playing sounds or music. Hard to sleep with an annoying spa. Any thoughts?

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  • mlloberg Nov 09, 2008

    Humming actually comes from the DC adapter. And is more like a high pitched squeel.

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If this is like my unit it is a high pitched squeal. I received my unit as a gift for Christmas 2007 and I thought it was defective. I contacted Homedics and they sent me a replacement but the problem persisted. As licensed amateur radio operator I am versed in electronics so I decided to track down the source of the noise. It turns out that the 16VDC power adapter is the source of the noise. It is what is called a "switching power supply" and is unfortunately not well filtered causing the high pitched squeal. I was able to get rid of the noise by modifying the power adapter and adding a 2200 microfarad capacitor in parallel with the output. This filters out the high frequency ripple and gets rid of the squeal. An alternative solution would be to search the Internet for a better 16VDC power adapter. It must supply 2 amps of power and have a 5.5mm OD/2.1mm ID center positive power connector.

Posted on Sep 27, 2009

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1) stray input pickup = Damaged cables, poor shielding,
Missing ground connections,
or ground loops.

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50 Hz in Europe and Asia
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Harmonics (multiples) may occur as Fourier components
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Sub-harmonics such as 25 Hz are mathematically
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1) Have you actually measured or observed the frequency
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2) Where are you, and what is your power line frequency?

=======

If you have line frequency noise, possibly stray pickup,
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