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Author Topic: Why Does Tranny The Transformer Hum ?  (Read 9361 times)

Offline neilep

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Why Does Tranny The Transformer Hum ?
« on: 13/02/2008 00:29:14 »
Dear all,

I have a sneaking suspicion that this may have been asked before but a quick search revealed nothing. If it has then I apologise to the original author (which might even be me...as I've done it before !......ask the same question twice that is !!)

This is Tranny the transformer.



See him there being all coy but ever so ready to transform some electrical stuff !

When I place my ear next to him I can hear him hum..(When he is ON that is !!)...why is this ?.....something is vibrating yes ?......what makes it hum ?

you see....I really do not have a clue !!......(yeah, I know....it's obvious isn't it ?)


 

Offline Karen W.

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Why Does Tranny The Transformer Hum ?
« Reply #1 on: 13/02/2008 02:05:31 »
Here is my guess. perhaps the big wire has to cut the power to a smaller voltage before transforming a larger current to a smaller safer current. which may mean a wire which may have more then one wire.... maybe they vibrate at the point of the transformer when the switch in power takes place.. thats my guess!
 
 

Offline DoctorBeaver

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Why Does Tranny The Transformer Hum ?
« Reply #2 on: 13/02/2008 07:58:42 »
Blame the constant reversing of the AC current. That switching back and forth excites the core and case, and makes them want to boogie on down. The hum is composed of harmonic frequencies.

In the U.S. the reversal happens 60 times per second (referred to as 60Hz - or 60 Hertz). This frequency and it's harmonics of 120Hz, 240Hz, are close to the musical note Bb. The 180Hz harmonic is close to F#.

F# is the augmented 5th of the Bb major scale. However, Bb is the natural 3rd in the F# major scale. This would imply that U.S. transformers like the key of F#. That is a key that was favoured by Franz Liszt.

"Mozart & Liszt" is Cockney slang for "drunk". "Drunk" rhymes with "clunk" which is a sound often heard when a relay is activated. Relay activation can be caused when a transformer is switched on. So there we have it - a connection between transformers, a Hungarian composer and Cockneys. I bet you never thought that could happen! :D
 

Offline daveshorts

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Why Does Tranny The Transformer Hum ?
« Reply #3 on: 13/02/2008 10:05:09 »
Yes the reason that it hums is that a transformer is basically two electromagnets wrapped around a piece of iron. When a current flows one will induce a current in the opposite direction in the other, this will mean the two electromagnets will attract one another and any bits of iron in the device.

As the alternating current drops to zero this force will go to zero, then as it increases in the other direction both will start to attract one another again. So the transformer will be vibrated at twice the mains frequency, and probably depending on the load it will have some components at the mains frequency and other multiples of it.
 

Offline that mad man

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Why Does Tranny The Transformer Hum ?
« Reply #4 on: 13/02/2008 17:20:50 »
As stated above the hum is produced by the contracting and expansion of the iron core due to the changing AC wave.

The iron core of a transformer is not just one chunk of iron and is usually made up of thin laminations of iron or steel clamped together. This make thing cheaper, helps stop eddy currents and lessens the hum produced from the supply freq.

You may notice this hum easier on cheaper or older transformers as their laminations may not be held as tight making for greater vibration.

Toroidal transformers however are more efficient and produce very little hum as they are made from a single strip of steel with the coils tightly wound.
 

Offline Karen W.

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Why Does Tranny The Transformer Hum ?
« Reply #5 on: 13/02/2008 18:16:26 »
OOOH That is interesting! Ours vibrate pretty loudly... there is also a red light that flashes from ours pole... Although it may not be on the transformer itself.. but it buzzes!
 

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Why Does Tranny The Transformer Hum ?
« Reply #6 on: 13/02/2008 23:12:29 »
You know how putting your finger on the high gain input of any amplifier produces 'hum'.
Well, in the UK the Hum is 50Hz (and harmonics) and in the US it's 60Hz so, somewhere in mid Atlantic, does the pitch of the hum suddenly change? Could you use it as a navigational aid?
 

Offline turnipsock

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Why Does Tranny The Transformer Hum ?
« Reply #7 on: 13/02/2008 23:44:40 »
Eddie Currents...that would be a good name to use on Wogan.
 

Offline neilep

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Why Does Tranny The Transformer Hum ?
« Reply #8 on: 14/02/2008 00:13:14 »
Blame the constant reversing of the AC current. That switching back and forth excites the core and case, and makes them want to boogie on down. The hum is composed of harmonic frequencies.

In the U.S. the reversal happens 60 times per second (referred to as 60Hz - or 60 Hertz). This frequency and it's harmonics of 120Hz, 240Hz, are close to the musical note Bb. The 180Hz harmonic is close to F#.

F# is the augmented 5th of the Bb major scale. However, Bb is the natural 3rd in the F# major scale. This would imply that U.S. transformers like the key of F#. That is a key that was favoured by Franz Liszt.

"Mozart & Liszt" is Cockney slang for "drunk". "Drunk" rhymes with "clunk" which is a sound often heard when a relay is activated. Relay activation can be caused when a transformer is switched on. So there we have it - a connection between transformers, a Hungarian composer and Cockneys. I bet you never thought that could happen! :D


Is your dam anywhere near the outlet pipe of a rehab clinic ?


This is wonderful Mr Beav.....funnily enough....bizarre I know....but you're right !.....the connections you cite were not on the tip of my tongue........
.but I thank you for the science and the explanation therein. :)
 

Offline neilep

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Why Does Tranny The Transformer Hum ?
« Reply #9 on: 14/02/2008 00:15:56 »
Yes the reason that it hums is that a transformer is basically two electromagnets wrapped around a piece of iron. When a current flows one will induce a current in the opposite direction in the other, this will mean the two electromagnets will attract one another and any bits of iron in the device.

As the alternating current drops to zero this force will go to zero, then as it increases in the other direction both will start to attract one another again. So the transformer will be vibrated at twice the mains frequency, and probably depending on the load it will have some components at the mains frequency and other multiples of it.

THANK YOU MR DAVE.......I understand it !!!......amazing !!!.....and without the aid of banal connections too ....and a safety net!!........ ;)
 

Offline neilep

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Why Does Tranny The Transformer Hum ?
« Reply #10 on: 14/02/2008 00:19:05 »
As stated above the hum is produced by the contracting and expansion of the iron core due to the changing AC wave.

The iron core of a transformer is not just one chunk of iron and is usually made up of thin laminations of iron or steel clamped together. This make thing cheaper, helps stop eddy currents and lessens the hum produced from the supply freq.

You may notice this hum easier on cheaper or older transformers as their laminations may not be held as tight making for greater vibration.

Toroidal transformers however are more efficient and produce very little hum as they are made from a single strip of steel with the coils tightly wound.


THANK YOU MR TMM.

Yes..yes..Toroidal transformers are the big round ones yes.....I have a couple of those in my Hi Fi amp !...and you are right...there is no hum !!...unless it's upon a music track by Laurie Anderson....

Thank you for your excellent information.
 

Offline DoctorBeaver

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Why Does Tranny The Transformer Hum ?
« Reply #11 on: 14/02/2008 15:08:37 »

Is your dam anywhere near the outlet pipe of a rehab clinic ?

No. It's in Amy Whitehouse's garden.
 

Offline neilep

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Why Does Tranny The Transformer Hum ?
« Reply #12 on: 14/02/2008 17:34:12 »

Is your dam anywhere near the outlet pipe of a rehab clinic ?

No. It's in Amy Whitehouse's garden.

Now THAT explains it all !! :o
 

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Why Does Tranny The Transformer Hum ?
« Reply #12 on: 14/02/2008 17:34:12 »

 

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