Looking for Copper tape for transformer shielding

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mkiijam

Well-known member
Joined
Aug 25, 2017
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170
Looking for .75" copper tape that is THICK.

Output transformer shielding, like the single wrap around the outside of the transformer.

Everything i have been finding is very thin stuff...
 
mkiijam said:
Looking for .75" copper tape that is THICK.

Output transformer shielding, like the single wrap around the outside of the transformer.

Everything i have been finding is very thin stuff...
maybe search shorting turns?

JR
 
yeah... still not seeing much. Hopefully somebody will chime in with something they have found.

Belly band in the U. K. (btw)
 
I quick search turns up adhesive backed copper tape... Others widths than 3/4" may be cheaper

https://www.amazon.com/s?k=3%2F4%22+copper+tape&i=arts-crafts&ref=nb_sb_noss_2
41cCFHpK7QL._AC_UL320_.jpg


JR
 
"Carrier Thickness (mm):0.025

Total Thickness (mm):0.06 ± 0.005"

WAY TOO THIN!

It's easy to find this stuff, it's just all too thin
 
mkiijam said:
Looking for .75" copper tape that is THICK.
Why? Define "thick"...it's easy, just a number, either gauge or thickness.
You may not find it in 3/4" width, though.

Everything i have been finding is very thin stuff...
Have you actually seen existing transformers with thick copper shield?

https://www.amazon.com/Copper-Sheet-Metal-12/dp/B00AKMNNX4
Is this acceptable?
Or That?
https://fr.aliexpress.com/item/32836404677.html?src=google&src=google&albch=shopping&acnt=494-037-6276&isdl=y&slnk=&plac=&mtctp=&albbt=Gploogle_7_shopping&aff_atform=google&aff_short_key=UneMJZVf&&albagn=888888&albcp=6459941648&albag=84161538224&trgt=743612850914&crea=fr32836404677&netw=u&device=c&albpg=743612850914&albpd=fr32836404677&gclid=Cj0KCQjw0Mb3BRCaARIsAPSNGpVHqz_F74u55GkQSoiJBEhsTJk9tE6JPTWGCHGYgkwVghyCzEFDgW4aAnMQEALw_wcB&gclsrc=aw.ds
 
mkiijam said:
Looking for .75" copper tape that is THICK.

Output transformer shielding, like the single wrap around the outside of the transformer.

Everything i have been finding is very thin stuff...
called the "belly-band". 
some discussion here:
https://www.vintage-radio.net/forum/showthread.php?t=110258
in my experience,  bands made of  thin copper.

examples:

Ampex 351 power,
0.5 mm thick, 32 mm wide

Hammond AO-29 power,
slightly thicker than 0.5 mm (difficult to measure without disassembly),
56 mm wide

Marantz 240 power,
slightly thicker than 0.5 mm,
56 mm wide




 
buy some thick copper and some double sided tape from 3M.  they make all types, not just the  wimpy clear stuff on the roll .

or jb weld the copper.

 
You don't need thick copper shielding. Copper is electrostatic shielding, and ANY thickness will guarantee the same effect.

What you may be thinking of is magnetic shielding - which is in effect not really shielding, but rather diversion of magnetic field lines. And because of the need to divert and contain as many field lines as possible for efficient shielding, thicker is better in this case.

But goes for magnetic, not for electrostatic shielding

/Jakob E.
 
gyraf said:
You don't need thick copper shielding. Copper is electrostatic shielding, and ANY thickness will guarantee the same effect.

What you may be thinking of is magnetic shielding - which is in effect not really shielding, but rather diversion of magnetic field lines. And because of the need to divert and contain as many field lines as possible for efficient shielding, thicker is better in this case.

But goes for magnetic, not for electrostatic shielding

/Jakob E.
That's why I asked the OP, but he seems not to be interested anymore...
 
It's for electrostatic shielding... "Belly-band"

I understand that any thickness will work. However, the thin stuff is harder to handle. It wrinkles easy, tears easy, etc.

something on the order of 2-3 times thicker. So, .008-.012 thick?
 
I would expect 1oz copper to be sufficient for most applications and not easily torn or wrinkled. As an alternative you can also buy adhesive backed copper foil sheets and then cut to size.  Some of these can be quite stiff.
 
I suppose if its an interwinding screen on an input transformer  the thin would tape is most appropriate ,
Sometimes you do see a band of copper around a mains transformer across the bobbin and core , seems like the shorted turn scenario  ,they definately seem to use heavier stuff in that application ,
Is electrostatically screening  the  windings on an output transformer from external sources likely to be of use,
Would using a shrouded transformer mounting or bell ends be an easier way to go and give an advantage of some magnetic screening as well ?

I wonder how would the presence of an electrostatic or magnetic screen affect incidental capacitance relative to the windings
would it be likely to change the response at high frequencies ?
 
Tubetec said:
I suppose if its an interwinding screen on an input transformer  the thin would tape is most appropriate ,
Sometimes you do see a band of copper around a mains transformer across the bobbin and core , seems like the shorted turn scenario  ,they definately seem to use heavier stuff in that application ,
Is electrostatically screening  the  windings on an output transformer from external sources likely to be of use,
Would using a shrouded transformer mounting or bell ends be an easier way to go and give an advantage of some magnetic screening as well ?

I wonder how would the presence of an electrostatic or magnetic screen affect incidental capacitance relative to the windings
would it be likely to change the response at high frequencies ?
Shorted turns are used to deviate the magnetic field emitted by the xfmr. It applies only to power xfmrs. bell ends are more expensive than a turn of copper, when they are available.
 
mkiijam said:
Looking for .75" copper tape that is THICK.

Output transformer shielding, like the single wrap around the outside of the transformer.

Everything i have been finding is very thin stuff...

I normally buy from Banzai, they have a good selection but this seems to be the thickest they have:

https://www.banzaimusic.com/copper-foil-pro-50mm-adhesive-1m.html

70u the others are all 30u
 
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