Whining about a Whining Outlet

December 8, 2008 6:06 AM

Why is this high-pitched whine coming from one of my outlets?

I recently replaced my USB hub, which was powered by a 5V/2.6A adapter, with a hub that is powered by a 5V/3.8A adapter. All of a sudden, there's a whine coming from the outlet where the adapter is plugged in. I tried moving it to other plugs within the same outlet set and even plugging it into my power strip (which has outlets to spare) but am getting the same whine.

Is there something wrong with the adapter, or am I overextending my outlet? I've got my laptop, monitor, printer and two hard drives plugged in, but even with them powered down and disconnected from the strip, there's the whine.

Help this grandson of a late electrician not embarrass his family name!

posted by sjuhawk31 to Technology (4 answers total)

Many switching power supplies make this kind of noise when operating correctly. Switching power supplies are appearing on many new products because they waste less electricity than the old linear power supplies. Like CRT TV noise, some are more sensitive to this kind of noise than others.
posted by jepler at 7:27 AM on December 8, 2008

Wikipedia has this to say about acoustic noise in switch-mode power supplies: "Inaudible to humans, unless they have a fan or are unloaded/malfunctioning [but t]he operating frequency of an unloaded SMPS is sometimes in the audible human range."
posted by jepler at 7:38 AM on December 8, 2008

Best answer: I had a power supply for a CD player do this once. It would whine for about 45 minutes until it warmed up, then went silent. Still worked fine though.
posted by sanka at 8:31 AM on December 8, 2008

Response by poster: Well it's stopped making the noise. The boss turned off the heat over the weekend, so maybe the office was too chilly and, like sanka said, the power supply was warming up.
posted by sjuhawk31 at 8:45 AM on December 8, 2008