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Help needed DIY shielding for toroid transformer

Hi,
I'm at the edge of my knowledge, what material would I need to fabric a DIY shielding for a toroid transformer? Would I really need the expensive and hard to source MU Metal, or will steel or aluminium do too? Or do I maybe need lead?

Instead of buying sheets of metal, the easiest solution would be to wrap tape around the transformer.
Amazon offers a variety of self adhesive tapes with a coating of:

-proper Mu-metal (0,8mm) but insanely expensive at 100€ for 2ft
-aluminium (0.075mm) 30-50m rolls.
-copper (0,05 mm) 30-50m rolls
-steel (1mm!) 1-6m rolls.

I'm leaning towards the steel tape, maker is "Gauder" should you like to google it.
Will this work at all?

Kind regards,
Tobi.

Good day
Dear @topa best way to solve you problem you need remove screws and relocate toroidal transformer on amp case and listen.
If you add metal shield on transformer sound is change to bad side (100% testing)
 
Couple of points, if I may..

1) Index the torroid. There is a null in the radiated field where the wires go in/out and again on the opposite side. Point this at the sensitive (input section) of your amp.

2) Distance. Get that transformer as far away from the electronics as possible.

3) Thick/ Very thick stainless steel (10mm +). Any shield needs to be high density, if not then its just decorative. If you use Iron then it will magnetise, so use Stainless.

Good luck
 
Austenitic stainless won't work. You need high permeability material to 'redirect' the magnetic fields away from the sensitive circuit:
https://www.uu.edu/dept/physics/scienceguys/2004Feb.cfm#:~:text=February 2004,some people call magnetic shielding.
I did this in my headphone amp:
20200418-121340.jpg

There is just a thin piece of steel between the transformer and the circuits (case is aluminium) but it was sufficient to reduce a slight hum below audibility.
 
I've got a graph somewhere, comparing materials vs effective EMC shielding at LF... let me go dig...

(It's def not true that iron/steel 'magnetises and becomes ineffective' in this use btw..)

In any case - good layout, and twisting wire-pairs by current-loop is the first and best defence against LF emc issues: always.
 


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