Wireless Charging Buzz/Hum/Whistle

[duketreo]

Have had DNA since November- great phone. Been using Nokia DT-900 since December with no problems. However, I have noticed a very faint high pitched buzz that starts when I put the phone on the charger. It lasts maybe a second or two. Is this normal?

Woke up today in the middle of the night and saw the battery was fully charged. I always pull the phone off when that is the case. This time I went to the phone and it was actually making that noise. I'm not particularly worried but was wondering if anybody knows what could be the cause?

Thanks.

Btw, I do use the Poetic Atmosphere case (highly recommended-not coming apart yet like some have experienced). I don't think that it would have anything to do with it because I think phone did this even without it.

 

[MikeLip]

The charger is inductive, and what you are hearing is the high frequency AC being pumped into the primary side of the transformer formed by the coil in the base, which is being sent to the secondary formed by the coil in your phone.. The noise can also be generated by the receiving coil in your phone as it's excited by the transmitting coil. High frequency AC is necessary for reasons which have to do with coil impedance vs frequency, and the higher frequency enables smaller coils. If it ran at 60 hertz like your line (or 50 hertz if your power grid supplies that) you'd have to have a big honkin coil (technical term) on both ends.

This is the same sort of thing that gives us those tiny little power adapters we get now, rather than the huge heavy wall warts we used to have to put up with. The adapters also have transformers in them - which is essentially what you create when you put your phone on the charging pad. The pad coil is the primary, the phone coil is secondary. Wall adapters now convert the AC input from line frequency to one like 50,000 hertz, which allows for much smaller devices.

You used to be able to hear lots of things, like electroluminescent watches. Casio watches with the button you push to make them glow often whined or whistled when you did that. Same thing - you were hearing the high frequency oscillator.

 

[msndrstood]

Fantastic explanation. Thank you. ...and I don't own either the charger or the phone but I'm sure we'll see this tech more in the future. :thumbup:

What?! ...I'm msndrstood.
via Gnex

 

[duketreo]

Thanks MikeLip. That was exactly what I was thinking ;-)

That was really a great post. I guess I don't need to get a new phone or charger!

 

[jamdmyers]

Have had DNA since November- great phone. Been using Nokia DT-900 since December with no problems. However, I have noticed a very faint high pitched buzz that starts when I put the phone on the charger. It lasts maybe a second or two. Is this normal?

Woke up today in the middle of the night and saw the battery was fully charged. I always pull the phone off when that is the case. This time I went to the phone and it was actually making that noise. I'm not particularly worried but was wondering if anybody knows what could be the cause?

Thanks.

Btw, I do use the Poetic Atmosphere case (highly recommended-not coming apart yet like some have experienced). I don't think that it would have anything to do with it because I think phone did this even without it.

Wow, How do you get any sleep!

 

[AndroidXTC]

Im using the Nokia 900 also no sounds so far

 

[MikeLip]

Im using the Nokia 900 also no sounds so far

I really want one of those, but they seem sort of expensive for something I can do by plugging it in. I know it seems odd considering my treatise above, but maybe I'm missing something. I do hate the idea of constantly using the USB connector since they seem fragile (although I've been using them for years and have never broken one - maybe I'm paranoid). I loves Blackberrys charging dock that you just set the phone on and two pins made connection to contacts on the base of the phone or, in the case of the 8330, contacts on the back. No concerns about breaking, simple. The Nokia 900 seems to be cheapest, but it's still $65 or something like that. Is there a better price somewhere else?

 

[antilles76]

I really want one of those, but they seem sort of expensive for something I can do by plugging it in. I know it seems odd considering my treatise above, but maybe I'm missing something. I do hate the idea of constantly using the USB connector since they seem fragile (although I've been using them for years and have never broken one - maybe I'm paranoid). I loves Blackberrys charging dock that you just set the phone on and two pins made connection to contacts on the base of the phone or, in the case of the 8330, contacts on the back. No concerns about breaking, simple. The Nokia 900 seems to be cheapest, but it's still $65 or something like that. Is there a better price somewhere else?

If you are eligible for the employee discount program at Verizon they are around $35.00.

 

[MikeLip]

If you are eligible for the employee discount program at Verizon they are around $35.00.

I wish But no, I'm not.

 

[AndroidXTC]

I got two of them on ebay for $39 each. They are great love this feature my phone is always charged. It also charges great right through the case I have it in. Its nice not to have to deal with all the cords.