High pitch Squeal when charging?!
 

Hi everyone, absolutely nothing wrong with my device :) (And trying to keep it that way!) - so far it has been amazing, but this morning i have an interesting issue!

I'm charging it at work using the mini-usb to old nokia converter, and have it plugged into my E71 charger (Small round connector type).

And it makes a really high pitched squeal of a noise.. Hard to explain, but a bit like gas escaping form a coke bottle when you open it - but higher pitched! Quite quiet, and no dogs have appeared at my window yet - but they might do!

I've un-plugged it for now, and going through the PC USB connector - no squeal...

Anyone else tried using that chargin method, and any other noises?
:)

Re: High pitch Squeal when charging?!
 

Yes. It woke me up the first time in the in the middle of the night. It usually happens when it is close to a full charge.

Re: High pitch Squeal when charging?!
 

thats really interesting and yes it's nearish a full charge.
Wonder if this is possibly causing issues to the device? eeeeek :confused::confused:

Re: High pitch Squeal when charging?!
 

I usually find this happens on any of the fast chargers - i.e. with the higher outputs. I've had it on my last few Nokia phones. I even had to dig out on older charger to useif I was sleeping, just so it didn't whine and squeel. It always sounds to me like it is trying to force the power in and constantly changes pitch and pulses as it charges (but tends to be more quiet when charging) - as soon as charging finishes, it makes a right racket!

However I don't believe it damages the phone - I can imagine the battery life may be affected from being charged so fast, but you would also assume that Nokia have built that into the battery/charging circuit designs.

I tend to be able to hear dog whistles - so this might not be as bad for some people! Pretty interesting though. The phone I currently use is an E65 (because my N900 has been sent away for repairs!) - and it whines like crazy with the charger that came with it!

Re: High pitch Squeal when charging?!
 

It's probably/most likely the AC/DC conversion circuitry making the whine noise.

Edit: The noise will become louder with cheaper capacitors... ahem Nokia....

Re: High pitch Squeal when charging?!
 

I too experience this problem and woke me up the first time!

Very odd, but glad to hear it isn't likely to damage my phone.

Re: High pitch Squeal when charging?!
 

> And it makes a really high pitched squeal of a noise

I'm another experiencing this auditory onslaught. It happens in both of the following situations:

i) Using the n900 supplied charger. The electronic wailing appears to come from the plug/charger itself.

ii) Using my previous N79 charger with the supplied USB adaptor. Note that this charger was able to charge the N79 in blissful silence.

Consequently, my N900 and I are no longer sleeping together - I've thrown it out into the spare room, it can get up to its noisy overnight charging antics there.

No other faults with the phone otherwise, and very pleased I am with it too.

Spann

Re: High pitch Squeal when charging?!
 

I have had thisissue as well. its quite annoying. One can dampen the noise by putting it on some material that "sucks" up the sound. I for one used a handkerchief package.

Re: High pitch Squeal when charging?!
 

Wow quite a few people with the same issue :)
Wonder if Quim or someone in the know could pester nokia to see if it's a known fault that we have to live with or if it's an unknown to nokia issue and they could get some brains on it? :)

By the sounds of it, it's not a huge problem, apart from the N900-User Divorces at night :)

Re: High pitch Squeal when charging?!
 

As was mentioned, this is caused by the switching circuitry in the charger as it regulates the output. Here's a little read on it i found with a quick google: linear vs switching chargers. Note that the "noise" the article talks about is EMI (electromagnetic interference), but it's clear that certain components can translate the electrical noise to acoustic noise. Also note that, as some people have observed, the noise becomes more pronounced as the battery is nearing full and the charger reduces the output to it. My LG charger does this, becoming very noisy when the phone isn't plugged in or the battery is full. I can also hear the noise of the power circuitry in my flat panel, and CRTs are audible to me when on. This is all due to electrical noise being converted to acoustic noise through one or more components.

Maybe Nokia will go to the dual mode charging circuitry the article talks about for their next flagship. I expect not, though. :/

Re: High pitch Squeal when charging?!
 

I've never heard of capacitors whining. All my SMPSUs that whine do so because of the thin sheets of metal that make up the core (not native English speaker, I'm drawing a blank on their name).

The sheets are supposed to be spot welded to ensure block operation. In later years, this has been phased out, since tightly packing the sheets eliminates vibration (and noise), some using a bit of raisin, some a plastic wrap.

However, shocks during transport, vibration, slight manufacturing errors etc can cause a separation and cause the whine since induced currents in the sheets cause them to attract and repel in-sync with the frequency.

In standard adapters, it was a hum (50-60Hz), but SMPSUs often run in the 10K range, which is roughly whine.

You can either replace the charger or fix it.

IF YOU RUIN ANYTHING I DON'T KNOW YOU.

One can open up the charger and locate the tiny transformer assembly. Once it's exposed, insulation raisin (used on most electronics) can be poured over and through the sheets to stop the vibration.

If you don't have any, SuperGlue and the sorts can be used if you make SURE it has been correctly dried (hint: it's not 5 minutes). Make sure you don't drown the unit, or else it will let current through or heat up and bad things happen.

You know what, if you're not comfortable with modifying stuff that works at high voltage, just buy another charger. Get one of those USB universals and use the cable. Or the PC.

Re: High pitch Squeal when charging?!
 

Or put the charger in a box stuffed with old socks. :D:D

Re: High pitch Squeal when charging?!
 

awwwwww keeping the n900 warm at night! i like!
better make it fire-proof socks!! just in case!
:cool:

Re: High pitch Squeal when charging?!
 

I'd be careful with that. The charger tends to get pretty hot while loading.

Re: High pitch Squeal when charging?!
 

Same here, but if i lock the the device the noise stops, put the screen back up and it starts again.

Re: High pitch Squeal when charging?!
 

Make sure that your not using a defective charger.

Here

Re: High pitch Squeal when charging?!
 

checked, all is fine with mine, still a bit squeally though :)

Re: High pitch Squeal when charging?!
 

My N91's old charger did that too after a few years of use...Then it burned my hand and I finally figured I should replace it with the N95's charger...This one doesn't make weird sounds yet :)

Re: High pitch Squeal when charging?!
 

I was going to ask about the EM of the n900. I've not, so far, had any problems with noise while charging (just as well as my Mo charges on the pillow and Teddy would complain if it kept him awake).

But I have an aux cable to connect the sound to the car stereo. With the old n95, I used to be able to plug in the charger, plug in the stereo output and listen to music for miles without worrying that I was killing the battery. With n900, just putting the aux cable near the device (let alone plugging in) caused a horrible whine on the stereo. I didn't unplug the charger so that might well be the cause. I was fairly certain it was due to the EM output of the n900 at the time. I only discovered it late last night, so no time to investigate.

But it sounds like n900 is packing a lot of power while charging!

Re: High pitch Squeal when charging?!
 

hehe, i wonder if the N900 was learning teddy-speak and actually just having a friendly conversation :)

Welcome back from Spain Kathy, good to see you in the threads again :)

At least i know i'm not the only one with this fault, and there has been no accidents - a bit more comforted now :)

Re: High pitch Squeal when charging?!
 

I don't have the N900 and its charger (yet). But the description sounds like could be caused by two possibilities:

1) The switchmode charger, when load gets lighter, does reduce its switching frequency. At some point is becomes so low that it falls to audible band. One reason to reduce frequency is to improve efficiency with lighter loads (likely to meet some Energy Star requirement...)

2) The N900, when getting to almost full battery, changes its internal charger behavior so that it starts to take charge current in bursts. (Kinda like trickle charging). The bursts frequency may be low enough to be in audible range. The bursting current causes a change in charger output filter inductors, which cause a change in its core magnetic flux. This change in flux tend to cause force that changes the inductor core shape slightly, and will be transmitted to air. (It is like piezoelectric effect.)

In either case, this is not a malfunction or defect, and there is not much you can do to help this.

Does everyone who has the N900 and factory supplied charger have this issue?

EDIT: Got my own N900 and noticed the same issue. However, I do use my old AC-4U charger with the USB adapter. Therefore I can confirm it is not an issue with AC10 charger, but N900 itself. Therefore the option 2) appear most likely correct answer... :)

Re: High pitch Squeal when charging?!
 

All my nokia chargers, from old 3.5mm to n900 whine.
I haven't heard n900 speakers make noises when gsm radio is active though, my older nokia phones all do that.
My N800 makes an extra higher pitched noise over the already high noise floor when the touchscreen is touched. The backlight seems to vary in brightness at lowest setting depending on sdio activity...

When you open your ears and eyes you'll discover that everything makes noises or flickers these days :)

Re: High pitch Squeal when charging?!
 

Whine:
That's because save from UPSs and high-power devices all chargers, adapters, etc make use of SMPSUs (the small and light chargers, as opposed to the old wall units that would break a window).

Flicker:
In Europe at least, all incandescent lighting is all but banned (In Romania it's about to get illegal to sell I hear), thus everyone moving to gas discharge lights. Minus the CFs that have SMPSUs inside (those whine), they all flash rapidly as the ballast pushes electrons in the gas (so to speak). 60Hz US, 50 everywhere else.

In addition to this, all backlights in panels, TFTs, etc use CF technology which is exactly like the flicker kind except they flicker faster and at higher voltage (making them flicker-"free" and efficient). However, as the gas oozes out with time, gets contaminated by the electrodes, etc, generally age they start to lose their effectiveness and only fully light every few cycles, effectively reducing the flicker from 100-600Hz for CF/TFT to around 50-60, making them slightly flicker.

In addition to that, most "on" and "standby" LEDs are wired into the power supply to see when it's dead, usually via a gas discharge small lamp (orange) or LED with a resistor and a diode. As a result, they are powered directly at mains frequency, thus, flicker. Orange find-in-the-dark light switches are easiest to see.

Add this to the fact that public illumination use 50/60 HZ had discharge (sodium lamps), and you see why it's true.

Yes, the whole world whines and flickers. Welcome to the 2000s.

20 years ago, it was all yellowish from the low-powered bulbs and it hummed at mains frequency. Those a little older know what I mean by this: TV hummed, fridge hummed, the stereo and radio hummed.

In fact, mains is in sync in the whole area so if you had very fine ears, the whole world would hum as the city concrete slightly moved the heartbeat of technology.

Re: High pitch Squeal when charging?!
 

I have always been super sensitive to noises.

My laptop PSU is too annoying to leave charging overnight. As others have said, its fine while charging but once finished its too loud.

I haven't noticed anything with my N900 though, although I wont leave that on overnight anyway as I will be using it to listen to music in bed last thing at night.

Re: High pitch Squeal when charging?!
 

I used to love taking walks in the middle of the night in the sleeping city and listen to the "beat" :)

Re: High pitch Squeal when charging?!
 

The n900 is generating a lot of EM when charging - further to my comment upthread about not being able to use an aux cable while charging, I can use it just fine when not charging. While charging, there;s a horrendous squeal comes over the speakers as the n900 it too 'hot' to be connected. Which is a bit of a bummer on long trips when you don't want to burn battery.