Frequencies given off by T41

[DaveMackenzie]

Hey guys,

Heres a weird one for you, how many people are using the wireless on the T41? ive used it from day one, but have noticed some weird things in conjunction with it, if i listen carefully, i can hear frequencies given off by the wireless card (directly under the touchpad) and the more activity i do, i.e. scrolling, the sounds get louder and are what i would say in ''sync'' with my actions, this was also the same with the lan port when i was using rj45 for the internet, if i scroll a page, maximise it etc, i hear a faint high pitched tone, maybe i just have super spider senses lol, but could i ask if there is anyone else out there who can hear this ?

[rkawakami]

Hmm.. first singing RAM and now a singing wireless card...

I would think that the wireless card is not the actual source of the high-pitched whine. The T23 I'm typing on right now has a similar problem (which I've basically ignored). I think what you are hearing is a coil or inductor in a power circuit somewhere which has a slightly loose winding. On my system the sound is sometimes louder one day to the next. The sound varies with scrolling around in a window (like yours). It is the only T23 I have that does this but it is also the only one which has a wireless card and an SXGA+ panel.

I'm hoping that as I age, the sound won't be as noticable .

[DaveMackenzie]

I think its mainly because its a radio device, however i've always had ears that pick up the faintest of sounds, my friend once played 1khz on his phone to me which apparently only dogs can hear, after hearing it i passed out and sadly was vomiting all afternoon!!!! i've seen various stories on the net about people suffering from the same condition around low frequencies, one woman couldnt move due to her router frequency (2.4ghz!!)

[anthean]

Sounds waves are produced by vibrating physical objects--in the case of a speaker, a vibrating diaphram.

Although I can't absolutely swear that no humans can "hear" EM waves, I really would suggest you first look for a more traditional cause than the wireless card.

[GomJabbar]

my friend once played 1khz on his phone to me which apparently only dogs can hear

There are sure a lot of us "dogs" out here that can here a 1khz tone.
[fortunately without your results]

[anthean]

Actually, my understanding is that the range of human hearing is from 20 Hz to 20 kHz.

See: Sensitivity of Human Ear

[jdhurst]

I just took a look with a general purpose scope, and the only signals given off near my T41 laptop are 60Hz hum frequencies and such signals are all over the laptop, not just at the wireless card. The radio waves are much too high a frequency to hear (or observe on a general purpose scope). There are circuits in GPRS transmitters that can be heard through speakers, but such does not exist (so far as I know) in wireless NIC's. The "low speed" circuits in the wireless transmitter are probably still too high to hear. There may be a defect in the wireless card, but it also may be another circuit. .. JD Hurst

[DaveMackenzie]

Its nothing worrying, but its just weird that i can hear it, i removed the touch pad whilst still using the laptop to get a closer look, its definately coming from the wireless card which is below the touchpad, ive seen similar in electrical items before, like a capacitor charging up to power a flash strobe in a camera, although that was a bit louder!!!

[depravedone]

I believe, with a high degree of certainty, that what you are in fact hearing is coming from the speakers. Its not uncommon for electrical noise to come through your speakers that is from RFI picked up by your computers audio circuirty. Not sure the source of the interference, CPU, RAM, etc. but I'm almost positive the SOUND you hear is coming from the speakers.

[rkawakami]

<snip>... like a capacitor charging up to power a flash strobe in a camera, although that was a bit louder!!!

The only time that I know of a capacitor making any kind of noise, is a "pop", followed by all of the "magic smoke" pouring out of a hole (which didn't exist previously). These were generally large electrolytic types which were dormant for some time (think: tube radios and televisions). The whine from a strobe is normally from the charging circuits (transformer, inductor, coils) as the high-frequency oscillator is used to convert a small DC voltage up to a larger one which charges a capacitor. I will admit that there is a small chance that the sound could be coming from a capacitor, but I'd place it at 1%.

It would easy to determine if the speakers are the source of the noise by simply removing them from the system. I would bet the noise would still be there. Same goes for the wireless card. Look around on the motherboard near the wireless card for an inductor (generally black, about 1/2" square, with copper wires usually visible wound around it). If you can operate the system with that component exposed, grab a long, thin wooden dowel (i.e., a chopstick), place one end on the component and place the other end near (not in!) your ear. Conduction of the sound along/within the wood should amplify the sound and allow you to pinpoint the source of the noise. If you really want to lessen/eliminate the noise then I suppose you could use a small amount of hot glue to encase the windings of the inductor and/or make sure it is firmly attached to the motherboard.

[coreman]

This is a problem that is becoming more frequent in NBs today because of all of the advanced technologies. The noise could be emanating from any number of ceramic capacitors on the motherboard. Thispaper talks about MLCC audible noise associated with CPU sleep mode but there are also reports wiht this type of noise coming from the LCD driver circuit as well. I've personally seen and heard the noise off a Power PC CPU (from Apple NB) where the capacitors mounted on the top of the CPU started humming under certain activities.

This noise could easily be from ceramic MLCCs on the wireless card...or other nearby functional sections.

[DaveMackenzie]

Right, well i disconnected the speakers, and ooh, the sound is still there lol! but i knew it wouldnt be the speakers, the thing is ive seen this on rf devices before, like for instance...walkie talkies, also, devices with a colour tft ie palmtops, heres a way to tell on a palmtop, put your power settings to turn the backlight off after one minute, hold the palmtop near your ear with the light off, touch the screen and oooh we hear a frequency type noise!!! i think its something to do with voltage stepping in certain devices, most back lights in devices are cold cathode tubes, which we all know require a different higher voltage, but anyway, as i said, its nothing annoying, its not really something u can hear, but i was just curious what it is, the next thing i will do is use my probe mic and place it near the wireless card and see what i can pick up. I cant believe i passed my electronic engineering degree with flying colours, i cant even understand my own laptop!!!!!
The sound is almost as if you can hear information going through, the more i demand on the network, ie checking my nas server through my computer, (mapped network drives) the sound gets more intense,