Why does my phone charger make a horrible high-pitched noise when it's plugged in? And can I stop it?

br549xt93 · 2 years

OMG! Mine does that too and it drives me crazy! I've noticed it with chargers for other things too, not just phones. I wonder if you can fix that...

iHelix150 · 2 years

Modern wall wart type transformers use what's called a switching power supply. It looks like this inside-

AC power ->  [transformer] -> [rectifier] -> [switch] -> [capacitor] -> output

Basically AC power is first stepped down to a lower voltage (a bit above the output voltage), then converted to DC (rectified) with a diode bridge. Here's where the interesting part happens- a special regulator circuit rapidly switches the power on and off. The capacitor smooths this out, creating a constant voltage. This output voltage is continuously sampled by the switching regulator so it knows if the capacitor needs more 'on' or 'off' time.
Think of it like a 10PSI water hose, connected with a T-junction to a balloon, and you want 5PSI output. So you constantly watch the output pressure guage and turn the water on when it hits 4.9PSI and off when it hits 5.1PSI. The balloon will absorb these pulses of pressure and result in a steady 5PSI output.
Now this switching circuit works fast- in the kilohertz range. Most switching power supplies use a switching frequency above 20-30KHz so the human ear can never hear it. However for one that is in the 10-20KHz range, the switching is sometimes translated into audio frequency noise by aging capacitors.
The noise changes based on how much power is being consumed by your phone. When the phone is consuming power, the switch is 'on' more often. When the phone uses less or no power (unplugged), the switch (even if it operates at a supersonic frequency) may only be 'on' one out of every several hundred cycles, which creates an audible tone in the capacitor.
Unfortunately the way to stop it is to just buy a new cell phone charger, ideally one that's not a cheap piece of shit. If your phone charger is not a cheap piece of shit (note that whether or not it's a cheap piece of shit has nothing to do with how much you paid for it) its possible its capacitors were damaged by spikes, surges or other bad quality power problems, in which case you should invest in a good quality surge suppressor with noise filtering.

nsfwdreamer · 2 years

It sounds like you are one of the rare people who can hear a transformer.

kabuto · 2 years

It's normal for transformers and AC adapters to make these nosies. It comes from energy losses that are transformed into mechanical energy generating these sounds.
I think the problem is that chargers/adapters are very small heavily integrated. If you would put the transformer farther away from the other parts you'd get less interference, but also a larger device. There may be other filtering methods to remove the hum, but I'm no engineer.
Here are a few Wikipedia links about this general topic: http://en.wikipedia.org/wiki/Mains_hum
http://en.wikipedia.org/wiki/Transformer

bobadobalina · 2 years

Have you ever walked by a big electric transformer and heard it buzzing or humming? The noise you hear is that equivalent.
The transformer coil is burning out. The reason is louder when the phone is charged is because the energy has no place to go so it remains in the charger. It keeps building up so the humming gets louder.
Don't worry. It will stop when your house goes up in flames.

cwstjnobbs · 2 years

It's normal for a transformer to make that noise, my laptop power brick does it too if it's plugged in but the laptop is off.
Here's an idea, unplug the damn thing when you are not using it. That annoying whine? That's the sound of wasted electricity.

esoterrorist · 2 years

/r/techsupport might be better. better yet would be an EE subreddit, if you can find one

jjbcn · 2 years

I have a lamp (an expensive angle-poise one!) that buzzes loudly for about a minute when first switched on. I asked an electronics engineer friend how to stop the buzz but he didn't know.

KirbyG · 2 years

I think it's handy.
BZZZZZZZZZZ. "Oh! Phone's done charging."

CapersandCheese · 2 years

Im glad you asked. I was wondering this a few days ago... I just opt to unplug it when it gets annoying. Running out of juice is solved by carrying an extra charger when Im out and being really good at finding outlets in public

lphoenix · 2 years

I can hear those too, and have actually had to get rid of several electronics because I just cannot stand it, can't be in same room with it, it drills right into your brain! The buzzing, the hum, aaaaagghhh! I try to avoid buying anything with an adapter but you can't always. Have had to get rid of every electric clock and now use only those that run on batteries, the hum!! We have a lot of power outages here, and I can tell the moment I walk in the door that the power's off, because it's so quiet, so peaceful, my house is like some ancient cathedral. I'd live off the grid if I could, but really, that's not going to happen.

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Tuesday 16 April 2013

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Tuesday 16 April 2013

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