Subject: Re: [linux-audio-user] hum from laptop soundcard
From: Frank Barknecht (fbar_AT_footils.org)
Date: Tue Apr 22 2003 - 12:19:21 EEST
Hallo,
Paul Winkler hat gesagt: // Paul Winkler wrote:
> On Sat, Apr 19, 2003 at 12:33:25PM +0200, Frank Barknecht wrote:
> > One can also try to cut the earth of the laptop's powers supply if
> > one has a death wish... ;) I mean, don't do that.
>
> I have the same buzz problem on my laptop...
> i wouldn't physically cut the prong, but I have used one of those
> little 2-prong to 3-prong adapters - common in the US, you can find them
> in any hardware store here, i assume there's an equivalent elsewhere.
> You probably know the type - about 1 inch square, it's got a standard US
> 3-prong outlet on one side and a 2-prong plug on the other,
> with a little tab that you're meant to screw into the center screw of
> the wall outlet.
> If you ensure that the tab doesn't contact anything grounded,
> voila, ground is broken.
>
> is this a safety hazard? I'm not really sure.
> Be careful.
Actually I'm also not sure, if it must be a safety hazard. I read
about this solution and I also asked Acer, if they could provide a
2-prong plugged cable for their laptops. They wrote me, that in
Germany they are not allowed to supply such a cable for their laptops,
but I could try to find one somewhere else...
I guess, that the case of a laptop is well isolated from its innards,
and also a lot of cases are plastic, so it seems.
But if it's not isolated, the user would be the ground connection
chosen, and that'll hurt. ;)
Then the epanorama docs say "Do not do this", because it's
"potentially very dangerous":
http://www.epanorama.net/documents/groundloop/problem_solving.html
They call the plug-solution a "cheater plug":
http://www.epanorama.net/documents/groundloop/cheater.gif
ciao
-- Frank Barknecht _ ______footils.org__
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