[geoges.ravel]

Please don't laugh if this is stupid.

I did my first DIY headphone amp and thinking of using aluminium sheets (initially designed for toasting potatos) as isolations. Is this stupid or it will do it?

 

[ericj]

Huh?

What are you hoping to isolate with 'em?

 

[eVITAERC]

Isolation of what? EMR? Electric current? Ripple? Moisture and fragrance?

 

[geoges.ravel]

Quote:

Originally Posted by eVITAERC Isolation of what? EMR? Electric current? Ripple? Moisture and fragrance?

isolate the transformer from the rest of the circuits
and isolate theradio frequence noises, I don't know, I hope it
will isolate what it can.

I don't need to isolate it from Moisture because it is build in a box
initially contains alcohol.

 

[eVITAERC]

In that case, aluminum foil works awsome! What's wrong with it?

 

[amb]

Aluminum is ok for shielding RFI, but does nothing for magnetic field leakage from power transformers.

If you are thinking of aluminum foil as in those that we use in the kitchen, they are structurally too soft to be near any circuit. A little dent and you can get a short somewhere.

 

[diablo9]

Quote:

Originally Posted by amb Aluminum is ok for shielding RFI, but does nothing for magnetic field leakage from power transformers. If you are thinking of aluminum foil as in those that we use in the kitchen, they are structurally too soft to be near any circuit. A little dent and you can get a short somewhere.

what about a thin iron board between AMP and PSU board?
I think its always better to have PSU and amp in different cases.

 

[amb]

Quote:

Originally Posted by diablo9 what about a thin iron board between AMP and PSU board?

It probably won't do much. The nature of magnetic fields is that you probably have to enclose the whole transformer in a ferrous box to adequately suppress it.

Quote:

I think its always better to have PSU and amp in different cases.

Yes, when it's practical to do so. Otherwise, plenty of distance between the transformer and sensitive audio circuitry helps.

 

[rickcr42]

Everything you need to know about shielding and then some

http://www.magnetic-shield.com/

 

[Garbz]

grr double post

 

[Garbz]

Putting some mu metal inbetween the transformer and circuit won't eliminate the magnetic field, however it will weaken it. THe further a field needs to travel the weaker it is.

Even if you can't enclose the transformer if you can make a sideways U shape and lock the transformer in like so:
Code:

[left] ----------- ------- | \ | / | ------- | -----------[/left]

then even that would weaken the magentic field to a degree.

 

[rickcr42]

Quote:

Putting some mu metal inbetween the transformer and circuit won't eliminate the magnetic field, however it will weaken it. THe further a field needs to travel the weaker it is.

I actually have sheets of the stuff (mu metal) and builing a total shield box even without major tools is a snap.I have even jury rigged some audio tranformer shields.Amazing product

 

[rellik]

dont you have to reanneal(sp?) mu-metal after bending or joining?

 

[adhoc]

Quote:

Originally Posted by rellik dont you have to reanneal(sp?) mu-metal after bending or joining?

yep, you do.

iirc there is some TI-made composite sheets that do NOT have to be re-annealed after bending for sale at Michael Percy Audio. You might like to check that out.

 

[rickcr42]

http://www.hamptone.com/fulltxs.htm