Toroid Transformer Vertical or Horizontal Mounting

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Hello,

I am Building a Stereo power amp (Class A) using two identical transformers (400VA Each), Each trans for each channel. Obviously Size is the issue, i need to make the Chassis as Slim as possible, so mounting the Transformer vertically makes a big difference & gives me lots of space inside the chassis aswell. I do see lots of Plus in mounting they vertically but are there any Minuses?

So, which is the best mounting method for toroid Trans, with which we (DIYers) may be able to avoid Humm, Crosstalks, interference and any other problems faced on DIY pojects because of Toroidal transformers.

Also i would like to ask, Which sections of a Toroidal transformer has lots of Electromagnetic Wave Emmitance, Top/Bottom or Side (Outer Diameter)

Any Help or Recommendation will be deeply appreciated.

Thanks & Best Regards.
SLAK
 
Official Court Jester
Joined 2003
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Horizontal vs Vertical: The only difference is going to be the weight of the bracket in your amp.

Toroids are self shielding in that there is no definite gap to form a magnetic field across.

If you are concerned about stray field you can put a shield over the whole toroid, but make sure you do not make a complete conduction path through the toroid. i.e a complete loop. This would be like a shorted secondary winding. not good
 
So, How about making a Barrier between the Amp Boards & the transformer, just like i have shown in the virtual images I made below.
Making a 1mm Steel or a 5mm thick Plastic wall/barrier between the transformers & the Amp boards. Also covering this wall with a thin layer of Leather. Will this method do any Good to shield the amp boards from Electromagnetic waves being emitted from the transformers? Or is it a waste of time to make these Barriers?
 

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Just another Moderator
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I'd use 3mm steel. I suspect 1mm won't make much of a difference, 5mm plastic I'd be surprised if it had any effect at all :) I can't see any reason the leather would help but if you have a theory on that I'm all ears! I used lead for a shield on my torroid years ago, which did have an effect but not as much as I would have liked, I since found out that steel is a much better attenuator for EMI.

Tony.
 
I'd use 3mm steel. I suspect 1mm won't make much of a difference, 5mm plastic I'd be surprised if it had any effect at all :) I can't see any reason the leather would help but if you have a theory on that I'm all ears! I used lead for a shield on my torroid years ago, which did have an effect but not as much as I would have liked, I since found out that steel is a much better attenuator for EMI.

Tony.

Hello,
To be Honest i did not come up with the Leather theory. Its just that not long ago i had opened up a Hi-End Amplifier (Chinese) the toroid transformers were contained in a special Round enclosure, i think steel was the material of the enclosure about 1mm thick & the outer surface of the enclosure was completely covered with some sought of leather material. I thought maybe the leather covering meant something.
 
It could be used as an insulator to ensure that there isn't a shorted turn.

Tony.

Yes, Maybe.

I'd use 3mm steel. I suspect 1mm won't make much of a difference.

In that case i will have to drop my plan to even make a barrier, Cutting a 3mm Steel Plate as per the required dimension seems a time consuming & a expensive process (using laser cutting method).
 
If width is an issue, can I ask if height or if there is a specific capacity (an enclosed bookshelf type box -- probably not good for airflow if it was enclosed on sides and top, but I have seen stranger make-do placement in Hong Kong) of the space you are putting the amp into?

If the overall width is the issue, then why not stack the amplifier part (transistors, boards, caps, heatsinks, speaker outputs, and stuff) in above the torrids? Torrids and big caps in below the amplifier part (and even this is flexible if height is not an issue). Torrids and a big cap bank run relatively cool already compared to the transistors so neither will cook each other in this arrangement. The torrids can then be laid flat and no brackets needed.

Up there I said if height is not an issue, then you could make it three levels if you are really strapped for width. Level 1 = torrids, level 2 = big cap bank, level 3 = amplifier boards and transistors.

At this point, if you do go vertical, you could even consider a very sleek looking modern looking computer mini-tower or tower -- there are a few depths and various heights you van pick from depending on your size amplifier build and the cooling needed (some come with air filters prefitted). Attach the heatsinks to some cut out holes on the side of the case. This could free you up from thinking about case fabrication and think more on on case modification. I have seen some really nice looking drool worthy skinny computer cases that were both plain black fronts with access doors and venting being used for HTPCs that I would use in a heartbeat. Think 2001 A Space Odyssey's black monolith (with feet and annoying blue LEDs). Yours would be a heat sinked monolith pre-drilled for fans.

The other way I was thinking was if you were into case fabrication, then why not make a separate case for the power source (torrids)? That way later on when you do find more space, these boxes can go side by side, or somewhat separated by whatever is constraining the width cable connected, or stacked on top of one another.

But i'm just saying, ya know...
 
If width is an issue, can I ask if height or if there is a specific capacity (an enclosed bookshelf type box -- probably not good for airflow if it was enclosed on sides and top, but I have seen stranger make-do placement in Hong Kong) of the space you are putting the amp into?

If the overall width is the issue, then why not stack the amplifier part (transistors, boards, caps, heatsinks, speaker outputs, and stuff) in above the torrids? Torrids and big caps in below the amplifier part (and even this is flexible if height is not an issue). Torrids and a big cap bank run relatively cool already compared to the transistors so neither will cook each other in this arrangement. The torrids can then be laid flat and no brackets needed.

Up there I said if height is not an issue, then you could make it three levels if you are really strapped for width. Level 1 = torrids, level 2 = big cap bank, level 3 = amplifier boards and transistors.

At this point, if you do go vertical, you could even consider a very sleek looking modern looking computer mini-tower or tower -- there are a few depths and various heights you van pick from depending on your size amplifier build and the cooling needed (some come with air filters prefitted). Attach the heatsinks to some cut out holes on the side of the case. This could free you up from thinking about case fabrication and think more on on case modification. I have seen some really nice looking drool worthy skinny computer cases that were both plain black fronts with access doors and venting being used for HTPCs that I would use in a heartbeat. Think 2001 A Space Odyssey's black monolith (with feet and annoying blue LEDs). Yours would be a heat sinked monolith pre-drilled for fans.

The other way I was thinking was if you were into case fabrication, then why not make a separate case for the power source (torrids)? That way later on when you do find more space, these boxes can go side by side, or somewhat separated by whatever is constraining the width cable connected, or stacked on top of one another.

But i'm just saying, ya know...

Voooah!!! Thats a big message.
I deeply appreciate your effort of taking your time to write it. Thanks
I will keep your recommendation in mind while doing the Project.
Thanks Again.
 
Just another Moderator
Joined 2003
Paid Member
In that case i will have to drop my plan to even make a barrier, Cutting a 3mm Steel Plate as per the required dimension seems a time consuming & a expensive process (using laser cutting method).

1mm might be adequate my comment on 3mm was based on some recollection of something I had read and not actual experience I have only used lead for sheilding. Have a look at this thread DIYHiFi.org • View topic - Power transformer shielding(external) at least one poster is saying that 1/4 inch aluminium is a good shield.

Tony.
 
Voooah!!! Thats a big message.
I deeply appreciate your effort of taking your time to write it. Thanks
I will keep your recommendation in mind while doing the Project.
Thanks Again.

No problem. I was waiting for some few laminations to dry/cure and didn't want to clean out my garage and have dust fall everything.

Hope that the project goes well and remember to post pictures later on.

OTAB
 
What about a steel band around the toroid?

The company I work for manufactures equipment used for EIS. Since these devices not only measure voltages and currents, but also supply them, they are equipped with an amplifier fed by a linear PSU.
The ~300 VA toroid (mounted vertical, BTW) is a custom made item that has a steel band around it. In the past they used toroids without the band, but in some cases the magnetic flux leakage, however low, was still too high. The steel band gives the leakage an easier path than air, so it stays confined to the band. The band is electrically connected to the chassis. No further magnetic shielding of any kind is employed.
 
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What about a steel band around the toroid?

The company I work for manufactures equipment used for EIS. Since these devices not only measure voltages and currents, but also supply them, they are equipped with an amplifier fed by a linear PSU.
The ~300 VA toroid (mounted vertical, BTW) is a custom made item that has a steel band around it. In the past they used toroids without the band, but in some cases the magnetic flux leakage, however low, was still too high. The steel band gives the leakage an easier path than air, so it stays confined to the band. The band is electrically connected to the chassis. No further magnetic shielding of any kind is employed.

That sounds interesting, might be worth a try. I found when building my moscode amps that if the toroid was too close to the chassis you could feel a small vibration in the chassis, so I mount mine on two 20mm thick wood strips lined with foam weather strip, tied down with cable ties. The same with crossover coils, if they are too close together they interact with each other.
Mac

The Book Worm - DIY Audio Ebooks and Manuals - Speakers, Moscode Amplifiers, Electronics, Map Reading, Free Capacitor Intro.
 
That should be no difference from mounting it bolted to the bottom of the chassis. A transformer can of course be installed anyway around as long as you dont short it , or create any shorted loops around the magnetic field .
The stray field can be directional of course which you might have to consider when having sensitive circuits.
 
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