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.

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

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

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

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

Make sure that your not using a defective charger.

Here

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

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

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!

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