AC Power Adapter Question

soulesschild

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I have a X2VGA by Neoya and it's been working great so far. However, I just noticed today that the AC adapter makes a high pitched whining noise when it's plugged in. Is this bad or good? I got a replacement from them under warranty but it also has the whine. Any thoughts or ideas?
 

soulesschild

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Describe the whine?

Does it sound like a transformer?

I'm completely noob, but its like a high pitched whine that happens when the adapter is plugged in. When I unplug the AC adapter, the whine stops. No idea what you mean by transformer.
 

soulesschild

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Does it mean its like going to explode or something???? Is there a place I can buy a generic one that's not from some crappy chinese factory with zero quality control???
 

RancidWAnnaRIot

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Hence, "another." They shouldn't whine.

Wrong... Please know what you're talking about before you post.. don't give people incorrect information

Anyway...

actually.. it's normal for AC adapters to whine...

if it's very loud.. it's probably a problem.. but if it's low.. like you have to put your ear up to it to hear it, or the room has to be quiet to hear it.. it's fine...

the AC adapter has a transformer in it.. they tend to make those sounds..

buzzing occurs because of magnetostriction.. basically the ferrous materials in the transformer contract and expand with the changing magnetic fields in the transformer.. causing the buzzing..
 

engiNURD

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Wrong... Please know what you're talking about before you post.. don't give people incorrect information

Anyway...

actually.. it's normal for AC adapters to whine...

if it's very loud.. it's probably a problem.. but if it's low.. like you have to put your ear up to it to hear it, or the room has to be quiet to hear it.. it's fine...

the AC adapter has a transformer in it.. they tend to make those sounds..

buzzing occurs because of magnetostriction.. basically the ferrous materials in the transformer contract and expand with the changing magnetic fields in the transformer.. causing the buzzing..

So you're telling me they SHOULD whine? Thats funny, because none of mine whine. Since I'm getting older, I figured I'd ask a little kid instead... and she didn't hear any whine either. I asked an electrical engineer, and he concurred with me... they shouldn't whine. Yet, you say I'm wrong. That means all of my AC adapters SHOULD whine, since my statement was that they shouldn't whine, right? Or was my statement simply incomplete? I'm not an electrical engineer, so I wouldn't know... I'm just trying to educate myself, since my knowledge is fairly limited in this field. Thanks for correcting me.
 

Frank4d

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Another possibility (since it is a high pitched whine) is that the adapter may contain a regulated switching power supply. If that is the case, the whine will be several kilohertz, not 120 hertz. I know some adapters for Linksys ethernet switches contain 3.3VDC supplies.
 

Adrenaline

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If it is a high pitched whine as opposed to a hum then it could very well be a switching PSU, a cheap one at that, operating in the range of human hearing.
 

Nenu

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All transformers generate noise, much of the time it is too quiet to notice.
A small whine noise could be a noisy transformer or a faulty one.
It could also be other components failing, I have had capacitors squeal at me.

It might be ok but as its so noisy that you need to wonder if it has a fault, its not fit for the purpose intended in a living room.
I'd get it replaced again.
 

RancidWAnnaRIot

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All transformers generate noise, much of the time it is too quiet to notice.
A small whine noise could be a noisy transformer or a faulty one.
It could also be other components failing, I have had capacitors squeal at me.

It might be ok but as its so noisy that you need to wonder if it has a fault, its not fit for the purpose intended in a living room.
I'd get it replaced again.

again.. it depends how loud it is... if the room needs to be completely quiet to even hear it.. it's probably ok.. i've seen that with many laptop supplies as well as PSP supplies.

WOW.. capacitors squealing? that's something hahah... are you sure it was a cap? normally they just pop, or start to leak (if they are electrolytic..)
 

RancidWAnnaRIot

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So you're telling me they SHOULD whine? Thats funny, because none of mine whine. Since I'm getting older, I figured I'd ask a little kid instead... and she didn't hear any whine either. I asked an electrical engineer, and he concurred with me... they shouldn't whine. Yet, you say I'm wrong. That means all of my AC adapters SHOULD whine, since my statement was that they shouldn't whine, right? Or was my statement simply incomplete? I'm not an electrical engineer, so I wouldn't know... I'm just trying to educate myself, since my knowledge is fairly limited in this field. Thanks for correcting me.

They ALL whine to a certain extent.. if it's not that loud it's fine... sometimes the vibration is so subtle you can't hear it.. but if you can hear it.. it doesn't mean it's fucked up.. do me a favor and walk around a power station and you'll hear loads of vibration from all the transformers (granted they are ALOT bigger)...

they're not supposed to whine?? lol..

FYI not all engineers know everything.. does he/she specialize in power systems? or have experience with power systems? ;) many Electrical engineers these days don't know shit about power systems...

BTW i'm an electrical engineer... ;)

But hey.. go ahead and tell the OP to get a 3rd replacement.... we'll see if the 3rd supply makes noise or not...

i've heard MANY laptop power supplies making faint whining sounds..
 

RancidWAnnaRIot

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Another possibility (since it is a high pitched whine) is that the adapter may contain a regulated switching power supply. If that is the case, the whine will be several kilohertz, not 120 hertz. I know some adapters for Linksys ethernet switches contain 3.3VDC supplies.

very possible.. humans can't hear 120Hz.. however.. he might be hearing a harmonic of 120Hz...
 

RancidWAnnaRIot

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If it is a high pitched whine as opposed to a hum then it could very well be a switching PSU, a cheap one at that, operating in the range of human hearing.

it probably is a switching supply since they are more efficient actually.. i'm sure they would use that in a laptop supply more so than a basic rectifier PLus LDO regulator
 

Nenu

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again.. it depends how loud it is... if the room needs to be completely quiet to even hear it.. it's probably ok.. i've seen that with many laptop supplies as well as PSP supplies.

WOW.. capacitors squealing? that's something hahah... are you sure it was a cap? normally they just pop, or start to leak (if they are electrolytic..)

Yes.
as an electronic engineer you should know that devices which vibrate/oscillate could produce an audible noise.

very possible.. humans can't hear 120Hz.. however.. he might be hearing a harmonic of 120Hz...
The human ear can easily hear 120Hz and much lower.

I'm not sure why you feel the need to post on every point made in this thread. When you do, be careful that you dont pass on misinformation.
especially after you have pulled other people up for the information they have posted!
 

RancidWAnnaRIot

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Yes.
as an electronic engineer you should know that devices which vibrate/oscillate could produce an audible noise.


The human ear can easily hear 120Hz and much lower.

I'm not sure why you feel the need to post on every point made in this thread. When you do, be careful that you dont pass on misinformation.
especially after you have pulled other people up for the information they have posted!


human range is from 20Hz - 20KHz.. i thought it was 300Hz to 20KHz.. my bad.. so you can hear the 60 Hz from the outlet.. if you're young..

I think the other poster got mixed up.. the voltage coming out of the wall is 120Vrms, while the frequency is 60Hz.. so it would be a 60Hz sound.. however.. if it's high pitched.. it's going ot be a harmonic of 60Hz... or.. it's something else vibrating..


I'm posting on every point because i want to. Also because most of what i say is probably more correct then some of the ridiculous shit i see posted in the electronics forums in general (not this thread though.. this one is alright..).... Plus, i'm willing to admit when I'm wrong (as you pointed out with the 120Hz thing).. ;p
 

RancidWAnnaRIot

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I agree, a retail unit shouldnt make enough noise to cause annoyance while in use.

the OP hasn't described if the sound is loud or low...

like i said.. if it's a low sound.. then it's probably fine.. if it's loud.. like annoying loud it's probably a problem and should be replaced...

i'm just saying..a very low whine is ok... that's it that's all
 

RancidWAnnaRIot

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OP:

if it's annoying you.. or if it still bothers you.. go ahead and get it replaced again.. just don't be surprised if the 3rd supply still makes noise..
 

Nenu

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the OP hasn't described if the sound is loud or low...

On the contrary, its noticable enough for him to make a new thread on a forum about it.
I'd say that it must be causing him an issue as he has already had it replaced once and came here to find out if he should ask for another replacement or put up with it.

I'd replace it as the excess noise could be indicative of issues like loosely bound transformer core plates (which will worsen) or other component failure / bad fitting or mounting.
Its also clearly annoying to have switched on which isnt something you expect from a new product.

My X2VGA power adapter (UK) makes no discernable noise.
i can barely hear it with my ear pressed to it.
 

RoBo

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So you're telling me they SHOULD whine? Thats funny, because none of mine whine. Since I'm getting older, I figured I'd ask a little kid instead... and she didn't hear any whine either. I asked an electrical engineer, and he concurred with me... they shouldn't whine. Yet, you say I'm wrong. That means all of my AC adapters SHOULD whine, since my statement was that they shouldn't whine, right? Or was my statement simply incomplete? I'm not an electrical engineer, so I wouldn't know... I'm just trying to educate myself, since my knowledge is fairly limited in this field. Thanks for correcting me.

Okay, 99.99999999999999999999999999999999999999R% whine.

Even if you have to put them right up to your ear to hear them.

But that said, they shouldn't be audiable from over a few meters whatsoever.
 

BrainEater

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All transformers generate forces (magnetoconstriction) , that are capable of generating noise.Rancid is totally correct about that.

Whether or not a transformer 'actually' generates noise is a different thing altogether.The companies that build transformers , may or may not take the required steps to eliminate this noise.These steps include varnish coats/taping/tensioning etc.....

I would suggest if you have a transformer that makes noise , it's probably a really cheap one/poorly manufactured.Noise from electrical components is generally avoided by quality builders , so it's a good measure of worksmanship.
 

soulesschild

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I'll start the process for another one, however, is there a place where I can buy a generic AC Adapter such as this one that will at least have some build quality? I doubt I could but I thought i'd give it a try.
 

Frank4d

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I think the other poster got mixed up.. the voltage coming out of the wall is 120Vrms, while the frequency is 60Hz.. so it would be a 60Hz sound.. however.. if it's high pitched.. it's going ot be a harmonic of 60Hz... or.. it's something else vibrating..

I didn't get it wrong at all. While the AC frequency for power coming out of the wall is 60Hz, the sound produced by a transformer plugged into it has a fundamental frequency of 120Hz.

BTW i'm an electrical engineer too.
 

Adrenaline

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I didn't get it wrong at all. While the AC frequency for power coming out of the wall is 60Hz, the sound produced by a transformer plugged into it has a fundamental frequency of 120Hz.

BTW i'm an electrical engineer too.

Yes this is correct. The magnetic materials expand under a magnetic field, the field direction does not matter. Therefore, during the positive half-cycle of current the material expands. At the zero crossing the material will contract back down, then at the negative half-cycle of current the material will expand again. This gives rise to the 120Hz fundamental frequency or twice the supply frequency.
 

Nenu

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I didn't get it wrong at all. While the AC frequency for power coming out of the wall is 60Hz, the sound produced by a transformer plugged into it has a fundamental frequency of 120Hz.

BTW i'm an electrical engineer too.

thirded :)
 

RancidWAnnaRIot

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I didn't get it wrong at all. While the AC frequency for power coming out of the wall is 60Hz, the sound produced by a transformer plugged into it has a fundamental frequency of 120Hz.

BTW i'm an electrical engineer too.

ok.. second harmonic.. i wasn't sure.. that's why i said ..it [might] be a harmonic of 60Hz.. which you just confirmed that 120 actuall is the fundamental though.. cause of the way the shit deforms.....

also, i thought i read 120Vrms, but i was wrong... nvm
 

RancidWAnnaRIot

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I'll start the process for another one, however, is there a place where I can buy a generic AC Adapter such as this one that will at least have some build quality? I doubt I could but I thought i'd give it a try.

i think you can find a replacement.. as long as it's the same spec as the one you have now, and the same connector... (i.e. just check to see that it supplies the same amount of DC voltage, and that that it has the same current rating...)

usuallly the supply has something that says "Output: 19.1V , 3A" or something.. just make sure the voltage and amperage match up with the replacement.. and make sure the connector is the same (i.e. center positive, or center negative, and connector size and shape).. i don't see why doing that wouldn't work..

Yes this is correct. The magnetic materials expand under a magnetic field, the field direction does not matter. Therefore, during the positive half-cycle of current the material expands. At the zero crossing the material will contract back down, then at the negative half-cycle of current the material will expand again. This gives rise to the 120Hz fundamental frequency or twice the supply frequency.

interesting.. good to know
 

Whatsisname

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yes they can, humans can hear as low as 20. 120hz is a little higher than Bb one octave below middle C. http://en.wikipedia.org/wiki/Hearing_(sense)

If you are going to lecture people about not knowing certain things then its time you get your shit together before talking about things you apparently aren't familiar with.

very possible.. humans can't hear 120Hz.. however.. he might be hearing a harmonic of 120Hz...

Once again its time for you to do some more reading. Age reduces the upper limit on our hearing, not the lower limit.
http://en.wikipedia.org/wiki/Psychoacoustic_model#Limits_of_perception

Furthermore, the frequency of the transformers noise will be primarily 120hz and harmonics. A contracting and expanding metal coil isn't going to care whether the voltage is positive or negative.
human range is from 20Hz - 20KHz.. i thought it was 300Hz to 20KHz.. my bad.. so you can hear the 60 Hz from the outlet.. if you're young..

I think the other poster got mixed up.. the voltage coming out of the wall is 120Vrms, while the frequency is 60Hz.. so it would be a 60Hz sound.. however.. if it's high pitched.. it's going ot be a harmonic of 60Hz... or.. it's something else vibrating..


I'm posting on every point because i want to. Also because most of what i say is probably more correct then some of the ridiculous shit i see posted in the electronics forums in general (not this thread though.. this one is alright..).... Plus, i'm willing to admit when I'm wrong (as you pointed out with the 120Hz thing).. ;p
 

RancidWAnnaRIot

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yes they can, humans can hear as low as 20. 120hz is a little higher than Bb one octave below middle C. http://en.wikipedia.org/wiki/Hearing_(sense)

If you are going to lecture people about not knowing certain things then its time you get your shit together before talking about things you apparently aren't familiar with.



Once again its time for you to do some more reading. Age reduces the upper limit on our hearing, not the lower limit.
http://en.wikipedia.org/wiki/Psychoacoustic_model#Limits_of_perception

Furthermore, the frequency of the transformers noise will be primarily 120hz and harmonics. A contracting and expanding metal coil isn't going to care whether the voltage is positive or negative.

we already went over that... no need to bring it up again (i guess you didn't read all the posts? :confused: )
 

gee

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If your wall adapter makes the "BMMMMM" buzz kind of sound you hear when you're walking past an electrical substation or a padmount transformer, you're hearing 60Hz/120Hz related tones.

A wall wart is an extremely poor audio transducer for 60/120Hz, so what you usually end up hearing is rectification noise in the transformer - rectifiers cutting in and out of conduction will cause abrupt changes in current through the transformer, which in turn causes the windings to vibrate. This creates a "buzz" with higher frequency components than 60/120Hz alone.

If it's more of a beep or whistle sound that you're hearing from the wall adapter, it's a switchmode power supply. Almost all cheap SMPS wall warts now are pulse skipping flyback designs, using a OnSemi NCP, Fairchild FPS or similar controller. They're very efficient, but they create a bit of noise. They switch at 50/100KHz inside when the output is out of regulation, but they shut off completely to save a bit of power when the output is OK - this "shutting on/shutting off" can happen from 5-500Hz depending on load. Under heavy loads, they run constantly and act quiet. :D

If you unplug the supply from the X2VGA and hear "tickticktick" with your ear next to the transformer, this is what you're hearing.

In any case, don't worry about it. As long as your wall adapter has CE/UL/CSA markings on it, it's fused inside - if anything goes "very wrong" with the adapter it'll just blow its fuses instead of burning down your house.
 

Susquehannock

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Beat_Dead_Horse.jpg
 

soulesschild

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If your wall adapter makes the "BMMMMM" buzz kind of sound you hear when you're walking past an electrical substation or a padmount transformer, you're hearing 60Hz/120Hz related tones.

A wall wart is an extremely poor audio transducer for 60/120Hz, so what you usually end up hearing is rectification noise in the transformer - rectifiers cutting in and out of conduction will cause abrupt changes in current through the transformer, which in turn causes the windings to vibrate. This creates a "buzz" with higher frequency components than 60/120Hz alone.

If it's more of a beep or whistle sound that you're hearing from the wall adapter, it's a switchmode power supply. Almost all cheap SMPS wall warts now are pulse skipping flyback designs, using a OnSemi NCP, Fairchild FPS or similar controller. They're very efficient, but they create a bit of noise. They switch at 50/100KHz inside when the output is out of regulation, but they shut off completely to save a bit of power when the output is OK - this "shutting on/shutting off" can happen from 5-500Hz depending on load. Under heavy loads, they run constantly and act quiet. :D

If you unplug the supply from the X2VGA and hear "tickticktick" with your ear next to the transformer, this is what you're hearing.

In any case, don't worry about it. As long as your wall adapter has CE/UL/CSA markings on it, it's fused inside - if anything goes "very wrong" with the adapter it'll just blow its fuses instead of burning down your house.

Man this has turned into a huge debate lol.

Anyway, got another one, it now doesn't make the sound when it's plugged in, so I'm hoping it'll be good to go now. Though this piece of information, are you saying if the noise only happens when I unplug it from the actual X2VGA2 unit, it's alright? Only if its making the noise WHILE its plugged in, means its bad. Right? :confused:
 

Thor

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we, once upon a time had a transformer in a vcr that buzzed, quite loudly and would transpose it into the audio. what we discovered it was in our case was that the wall outlet we had it plugged into wasnt getting a 60hz signal, it was more like 58hz... had something to do with feedback comeing from a old microwave on the other side of the wall, ( we had a friend with an o-scope come over and test it for us... it only occured in this one socket, and as the house was new we wanted to be sure it wasnt a grounding problem wth that outlet.. )

he explained it as, becuase the transformer was designed to be ran at 60hz, moveing it up or down changed it resonance frequency within the houseing causeing it to buzz...

while in this case, a new one fixes the issue, you might want to consider the devices you have plugged into/around it, and what kind of noise they are putting back onto the line.. pumps, A/C fan moters, other wall warts, ect could be throwing it off...

just a thought..
 
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