this post was submitted on 17 Feb 2024
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We have a VR system set up in our living room. I don't even want to talk about how long it took me to figure out the receivers were making a steady, high pitched noise. There are 4 of them and they are situated near the ceiling.
I hear it from a lot of things when it's quiet enough. Clock radios, tvs, monitors, my pugmill, heaters. There was a noisy power strip with a flashing one-off switch that I'm still convinced was going to kill someone.
I DON'T know anything about electricity - so mostly it makes me anxious that my house is going to burn down. I have bad enough hearing loss that I have to use closed captions on my TV - but it IS mostly because deep voices are extremely muddled. I'm surprised a bit by how many "not really" answers I see.
Well the flashing light is just a tiny low current neon tube that can't hurt anything. The main thing to worry about with power strips is that they securely hold the connectors in place and not overloading them with more than their rated power, and the power of the circuit they are attached to in your home.
Switching power supplies for cheap consumer stuff are usually operating in the 20-30 kilohertz range. This is just outside of the audible range. What you are hearing is usually the windings or powder ferrite core of the miniature transformer physically vibrating. The audible sound is likely some lower order harmonic resonant peak that is in the audible range.
At the manufacturing level, the frequency of switching can be tuned to avoid unwanted noise, and the magnetics can be potted in a resin or other techniques used to dampen the vibrations. If you build your own power supplies like I have, they tend to make a lot more noise at the first prototype stage.
It's all Science Magic to me. I am continuously thrilled that the world is filled with people who are much smarter and more curious than I am.
I'll sleep a little better knowing the quiet strip flickering under my aquarium isn't a ticking time-bomb though.