shielding for non metal enclosures
Old 23rd May 2012
  #1
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jrp's Avatar
 

Thread Starter
shielding for non metal enclosures

Hello!
If i want to use an enclosure that is not made from metal for an analog, unbalanced, maybe higher impedance circuit, is it sufficiant to glue a layer of aluminium foil to the inside of the box? (and ground it, of course)
I know it will work to a degree, i´m just not sure if it will work any less than a normal steel sheet enclosure.
Old 23rd May 2012
  #2
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Hi
Depends if it is capacitive or inductive effect you are trying to stop.
Capacitive can use 'conductive' paint, often done to meet EMI regulations.
Inductive is often down to proper design.
Matt S
Old 24th May 2012
  #3
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The answer is:
"It depends"

On:
How good a job you do applying it and the frequency of the interference. Sheet steel works lot's better at low frequencies.
Old 24th May 2012
  #4
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vince @ speck's Avatar
 

Depends on the frequency spectrum that you are shielding against.

Foil, copper, and conductive paints provide "reflective" shielding for the upper band RF frequencies (>10KHz). You also need "absorptive" shielding... like mu-metal or thick steel for the low frequency (<10KHz) electro-magnetic fields like A.C. transformers.
Old 24th May 2012
  #5
Gear maniac
 

Try to get cheap 3M ultraperm 80 sheet, if you found < $8 A4 Sheet from mill. surplus provider. Beware with overpriced sheets or cutted sheets on ebay or "esoterics" alloys advertising.

Foil, copper & space got good results also.

Why I said ultraperm & mill. surplus ? because I ever found ultraperm cheaper than copper and others alloys, on a RAF spare parts sellers. I think, this surplus/spare providers maybe are more common in U.S. Or maybe 3M USA sell on retail.

Make a double sided with one sheet, facing the two adhesive sides. The effectiveness is better and very high with a thin and high malleability. Be careful, the edges can cut like a knife.
Old 24th May 2012
  #6
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jrp's Avatar
 

Thread Starter
Thank you!
I have noticed that when i breadboard a prototype without an enclosure it picks up hum and buzzing noise.
As soon as it´s in a steel enclosure hum and noise is gone.
That is the effect i am after.
Basically i am thinking about building some circuits in nice wooden boxes.
Old 25th May 2012
  #7
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brianroth's Avatar
 

Put the circuit in a steel box and then build a wooden shell to enclose the steel box?

Best,

Bri
Old 25th May 2012
  #8
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jrp's Avatar
 

Thread Starter
sure, that idea comes to mind. I was just curious if this is necesary or if a layer of aluminium will be just as good for the task.
(And, instead of making my own experimants i use this forum to see what you have to say... thank you!)
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