[Trac #1025] display noise at mid brightness

Zarro Boogs per Child bugtracker at laptop.org
Wed Mar 14 04:11:17 EDT 2007


#1025: display noise at mid brightness
---------------------------+------------------------------------------------
 Reporter:  AlbertCahalan  |        Owner:  mlj      
     Type:  defect         |       Status:  new      
 Priority:  low            |    Milestone:  Untriaged
Component:  hardware       |   Resolution:           
 Keywords:                 |  
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Comment (by gnu):

 My B2 also makes a noise -- I was surprised to hear it, but when I put my
 ear up to the left and right bezels, I can clearly hear a buzzing.  In a
 no-moving-parts unit, I thought this would be unusual.  But it turns out
 that there is a part that's designed to move -- the '''speakers'''.  When
 the volume control is not off, they amplify electronic noise from within
 the unit.  Changing the volume level using the keyboard buttons makes it
 clear where the noise (in my machine) is coming from.

 Others have reported noise when OFW scrolls the screen.  I haven't tried
 that and also haven't tried changing the volume from OFW and seeing if it
 changes the amplification of the noise. Making the CPU and/or the screen
 active could easily change the pitch and volume of the digital noise
 that's being amplified here.

 Better shielding of the analog audio section before the amp -- or some
 kind of analog squelch circuit that won't light up the speakers unless the
 signal is above a certain level -- might fix it.  Or it could be largely
 fixed in software: when nothing is playing through the audio subsystem,
 the amp volume could be set to zero (and restored to its proper value upon
 opening the device).

-- 
Ticket URL: <http://dev.laptop.org/ticket/1025#comment:1>
One Laptop Per Child <http://laptop.org/>



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