I too have noticed this when connecting my Dell Inspiron 9100 to the TV 
to watch videos.  The audio is absoultly horrible.  If I disconnect the 
power supply from the laptop all noise stops.
If anybody has solutions to fix this problem I'm all ears.

   -Dan


Mike Hord wrote:

>Medium-to-long explanation follows this executive summary:
>
>Has anyone noticed any noise issues related to Dell laptop
>power supplies?
>
>Full story:
>
>I'm working with meidum precision analog signals-
>16 bit (hopefully).  We were noticing intermittent noise in
>the output, which was usually present.  The acquistion
>system is connected to the computer via vanilla serial
>(no USB adapter, just a port on the laptop).  Finally, the
>noise can be eliminated by unplugging the supply from
>the laptop.  Unplugging the supply from the wall doesn't
>help, only unplugging the supply from the laptop.
>
>The long-term solution is optical isolation, but I'm curious
>as to whether this is something others have encountered.
>
>We haven't tried connecting it to other PCs yet, as we
>don't have any on hand for testing.  I did notice a similar
>problem with my newer model Inspiron- terrible noise
>when I connect to my stereo for listening to music.
>
>Mike H.
>
>  
>

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