Laptop makes audible high frequency sound when AC adaptor is plugged in?

It seems when I'm using my laptop on just battery, the noise is neutralised, also it seems to go away with the charger and battery are in constant use.

when I use the laptop purely on AC power, it makes this high frequency sound only really noticeable when you put your ear to the machine or near the fan.

is this down to something serious or normal and why does it happen?

 

where is the noise exactly? Does it just sound like the fan is running at full speed? or is it coming from the hardrives? or the psu itself? can you give better detail?

 

Lemme guess, it's the Sony?

 

No, it's Fujitsu, seems I'm pretty infamous on this forum for making useless threads.

 

I am not sure to be honest, the sound seems to come from all over the machine.
It's like a very loud high pitch sound only really noticeable when you put your ear next to the machine, it comes out of the fans and also from the hard drive at the opposite end of the machine.

 

Unplug peripherals to rule each of them out. Like hard drive, optical drive.

 

YouTube - Dell 1720 high frequency sounds

It sounds like this.

 

Hrm well I had a Fujitsu and a Gateway in for service before with the same issue. The Fujitsu turned out to be a bad AC adapter and the Gateway had a bad motherboard and bad AC adapter. See if you can find a known good AC adapter to test out your notebook.

 

you think its a motherboard/power issue?

should I use my warranty?

 

Possibly, the fact when it only makes the noise when the AC adapter is plugged in isn't just coincidental I believe. See if you can root out the problem yourself, visit your local computer store and see if it can get checked out. Fujitsu doesn't have many ASP's so it will be tough by shipping it out for warranty repair.

 

This is most likely caused from the piezoelectric affect of the inductors used in your laptop power supplies. I would run it for a while and see if it gets worse. If it doesn't get worse I would not worry about it.

I don’t know how much time you have left on the warranty, but to me having someone take apart and mess with a laptop scares me a lot more than a high pitched noise.

 

All computers make that noise. Its nothing to worry about.

If you send it in for warranty, they wont do anything about it.

 

Except last time the customer with the Gateway said she used it for months on months. Don't know if that contributed to her fried motherboard but just a word of warning, if something isn't normal usually your gut feeling takes over. I would have that looked at. Better safe than sorry.

 

The sound your describing is constantly asked about in laptop AC adapters, sometimes it can get quite annoying, but it is no different inside the laptop. It really is not something to be overly concerned about.

Because the sound is only heard when plugged in tells me it's most likely the inductor that is used in the battery charge circuit. Why it all the sudden appears is because over time from thermal cycling the tiny wire windings of the inductor will micro expand and contract over time. When the battery is taking a charge the circuit switches at a very high frequency, however the fine control to keep the currrent constant can modulate at a frequency that is in the audible range. When this happens the inductor "rings" or "vibrates" at that audible frequency. That is what your hearing. It does not mean you have impending failure.

 

Yeah, what exactly do you mean by "have that looked at"?

Lets all powerup our laptop motherboards without the casing and break out the multimeter shall we?

Yes, exactly.
Thats a good description. I don't really need specifics like that tho, imagination based on all integrated electronics relating to frequencies is good enough.

 

Try the following and check if the noise goes away:

-plug in the AC plug and remove the battery before you power on your laptop.
-disconnect all USB devices plugged into the laptop.
-turn off wireless from switch (a crystal oscillator could make this noise, there are more than one inside your laptop)
-close laptop lid so the screen is off but the rest is still running. (the inverter could make that noise) or simply switch to a different display
-set harddrive to turn itself off after X minutes, wait X minutes till you hear it's off (don't forget to set it back when you're done)
-try plugging your AC adapter in a diff outlet preferrably a diff room.

Does it make this high-pitched noise with CPU at idle only, under load or both?

 

Fine, but remember it's a public forum. Consider his definition for those that like/need a more detailed answer. Your abbreviated version will suffice for all the rest.

Incidentally, I consider any manufacturer that makes a device that operates with an electrical sound you can hear poorly built. I suggest you look around for an alternative that is better constructed.

 

I do consider that.
Its a pretty personal thing.

Although there is something about the description that I find slightly vague. I guess I think if one is going to go there, it should be explained from the point of view of some more fundamental principles of physics and electronics.

For example, if someone had asked me personally EXACTLY what is make the noise, I would describe to them how a speaker driver works.
All resistors and inductors are based on this same concept which has to do with creating magnetic fields. The only difference is that inductors do not have a musical signal going through them, and they aren't actually supposed to be vibrating around.

I believe that is much more informative on the specific subject whereas you went into more detail about motherboard layout.

Something else to consider is that inductors are not only in the battery charging circuit. Some graphics cards have inductors right on the board.
So its not necessarily thermal expansion that makes the change either, like Twiz implied, when the CPU is under load it will draw more power from inductors as well.

I'm not trying to argue or shoot you down here at all, othonda. Like I said in my 2nd sentence above, its personal and by that I mean there are a lot of points of view which all help peoples understanding. But the thing here is that its not a measurable or absolute thing at all, I don't think anyone could trace some of these noises back to specifics and figure out why they are at that exact pitch.

Although, Richard D James is someone who got to the point of making music with electronics and no speaker.

I wouldn't be talking about this if I hadn't experienced it myself a lot and I didn't find it so interesting. My graphics card makes a noise under load, and the pitch gets higher and lower in perfect sync with the amount of load.

 

After I had a run in by someone in this forum for implying something totally off base about me, I chastised the poster and after further explanation by said poster I realize that things can easily be misconstrued. With that I learned that I needed to toughen up my skin and not take things personal around here. That’s the only thing I can say about your comment. You can take that as advice or not.

One thing in my mind that is a problem when posting is how detailed to explain things. While there are some people around here that understand engineering of electronic and mechanical systems, as well as physics there are a lot of people that don’t. Another factor for me is that while I like laptops as a hobby sort of thing, I spend 8-9 hours every work day for the past 25+ years as an EE. So for me to get too detailed it starts to be like work and less of a hobby. If forums like this existed back in the 80’s or 90’s I would be all over this, but as I have gotten older the realization that too much of good thing (i.e. doing stuff outside work that relates to my career) isn’t necessarily a good thing as you become a one dimensional person. (I.e. you live up to the engineering stereotype of a total geek) anyway enough of that rant………

Have you not heard of speaker crossovers? They use Inductors. The vibrations are mechanical and cannot be totally eliminated. When AC currents (which are changing in frequency and load) pass through an inductor that are in the audible hearing range (typically 20HZ-20KHZ) the possibility exists that you could hear this. If you think this translates to a bad design or low quality you would be foolish to think that. As an example, If you open up a typical laptop power supply they have a ton of white RTV glue all over the transformers and inductors. This is an attempt to try and suppress the mechanical vibrations so the thing does not hum or make a high pitched sound.

Actually any external video card (non IGP) will have it’s own supply that will use Inductors.

My explanation of the thermal expansion was correct in the way I used it. If you read carefully. “Why it all the sudden appears” is because of the thermal expansion. So in other words if an inductor at one time was quiet but now make a high pitched sound can be caused by repeated thermal cycling over time. But yes as I described above and a twiz implied, just the very fact you have an AC currents can cause the noise.

I thought about this today and yeah it really could be caused from any number of the different supplies in the laptop, from the inverter, battery charger, any of the main power supplies (I did a quick count of the supplies in my sager and at least six of them have inductors)

Healthy discussion is fine with me. See my response to the personal thing.

I do beg to differ that anyone could not trace the cause of these noises. I do a lot of power supply design, the products I work on are similar to laptops in that we have several different supply voltages. I will say that if the noise was loud enough to be annoying, I would figure out where it was coming from. If it can be reduced to an acceptable level, is it possible to change the design to minimize it, and if all else fails, apply a wad of RTV on the inductor and move on

 

Not sur ewhat you mean, I just know this has been a problem with Sony.

 

Hi guys

I've gone through approx 3 laptops with the i3 processor, two diffrent types of Asus and a Fujitsu, all had a i3 processor running at 2.4GHz, all of them made a high pitch sound which made my ears feel like they were going to bleed.

I decided to go for AMD, and behold.. SILENCE...

I don't care if I sacrificed 0.2GHz of power, I can work in peace....

is this a known problem with them?

 

Ummm never heard anything from mine except the fan noise,and hard drive but nothing like you describe.Maybe it was the heat pipe boiling inside letting off steam like a tea pot......lol.
Glad mine doesnt make that noise,so far so good.

 

Isn't it an urban myth that i3 makes noises...?

 

Well I had three i3 laptops and they all made a high frequency sound which drove me crazy, maybe its because I'm under 25 and can hear high frequency stuff.

 

I'm with this. It was probably the fan or something.

@above: I'm 18 and I don't hear anything from my i5.

 

The Asus U35JC guys talk about this a lot and I've seen it mentioned with Acer and Sony models though I don't know if its the same cause. There was a thread on the Asus forums that it happens when the CPU goes into C3 sleep. It seems the sound is created by current cycling through capacitors on the motherboard. Users said disabling the sleep states in BIOS solved the problem. Some have also said that internet browsers affect it too. I've never heard or dealt with it personally though.

 

Maybe because I am totally nonprofessional, I believe there is a way to use common knowledge and basic terminology to explain most things in a very short and simple way.
Actually when it gets to a certain point I usually just start anthropomorphizing, which is a big help for some people. The problem there is that they usually don't believe its that simple, something that I got past pretty quickly. I just observe things with physics and engineering in mind and it generally confirms that I think about things accurately.
I also think that the main people don't understand technology is that its an uncomfortable thing to do. I believe they deal with equally if not more complex things on a day to day basis.

Essentially (if were going to rant ) I've always had the fear that I will become totally one dimensional in the way I think and obsess about technology. No one in my family has ever been technically minded. They are 90% musicians, mostly professional. I think about technology in the same way.
Actually its probably because of this that I am incapable of being employed

Yea, I know speaker crossovers use inductors. What made you think I didn't? All I was saying is that producing a pitch is not the primary purpose of the inductor itself.

Especially as someone into circuit bending, i do not at all think of bad quality when it comes to excess noise in electronics.
We should just not have tweeters, and use inductors instead
And yes, I knew that they use glue for that, although I didn't know it was called RTV. Perhaps power supplies should simply have acoustic silencing on the inside.

I wouldn't know, I don't have any IGP laptops

You are totally correct about thermal expansion I'm sure, I was saying I think it is just as likely that the GPU or CPU when under stress will cause more power to be drawn from the inductors thus they create more noise.

My experience confirms this, as I said before, my graphics card will make one distinct pitch at 90% load and another at 60%. It does this in perfect sync. So in this it is not thermal expansion, or else the noise would just change in pitch or volume gradually with the temperature of the card.

Also I sometimes get a pitch when I maximize a window or something. It happens immediately and then sticks until I find something else to display, sometimes it makes it stop and sometimes it doesn't.

When you get into the analog side of this phenomenon, it gets really interesting and cool. Sometimes I spend all night with my TV muted, which seems fairly quiet. Then there will be one commercial with large very bright red letters filling the screen on a white background, and it will produce a very distinct pitch. This happens much more reliably because it is analog. If I listen carefully I can always hear crazy phasing noises perfectly synced with various colors, shapes and movements on the screen (and no, I'm not crazy)

I know you could find the inductors that were making the noise. What I'm saying here is that no one could definitively determine what was causing them to make the particular pitch they did. Especially when it is caused by GPU or CPU stress. You would have to find out why the power was at different frequencies with different amp draw, things like that. Actually it does sound possible, just crazy.

Anyway.
I cant tell if this thread is getting way too on topic or off topic

 

It's not the processor itself but certain power supply (internal dc/dc supply) components.

Not much to do but complain to Asus to pressure them to replace the machine.

There are a number of laptops from various makers that do this.

'hetrodyne noise' from the internal psu is what you are hearing.

 

Your sonic hearing theory aside, newsposter is right. It is the power circuitry that is doing that. It is exactly like when you walk near a large power transformer you can hear a hum.

 

It would make crackling sounds through the earphones even when the laptop was turned off, I'm waiting on a new AC adaptor as that seems the source of the noise.