Looking for Copper tape for transformer shielding
« on: June 23, 2020, 01:54:30 PM »
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...


JohnRoberts

Re: Looking for Copper tape for transformer shielding
« Reply #1 on: June 23, 2020, 02:02:17 PM »
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
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Re: Looking for Copper tape for transformer shielding
« Reply #2 on: June 23, 2020, 02:50:21 PM »
yeah... still not seeing much. Hopefully somebody will chime in with something they have found.

Belly band in the U. K. (btw)

JohnRoberts

Re: Looking for Copper tape for transformer shielding
« Reply #3 on: June 23, 2020, 03:18:43 PM »
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


JR
Don't only half-ass tune your drums. Visit https://circularscience.com to hear what properly "cleared" drums sound like.

Re: Looking for Copper tape for transformer shielding
« Reply #4 on: June 23, 2020, 04:34:00 PM »
"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

abbey road d enfer

Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Re: Looking for Copper tape for transformer shielding
« Reply #6 on: June 23, 2020, 05:19:49 PM »
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




« Last Edit: June 23, 2020, 06:51:12 PM by gridcurrent »

CJ

Re: Looking for Copper tape for transformer shielding
« Reply #7 on: June 23, 2020, 09:52:45 PM »
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.

If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

gyraf

Re: Looking for Copper tape for transformer shielding
« Reply #8 on: June 24, 2020, 07:06:22 AM »
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.
..note to self: don't let Harman run your company..

abbey road d enfer

Re: Looking for Copper tape for transformer shielding
« Reply #9 on: June 24, 2020, 07:13:39 AM »
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...
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.


Re: Looking for Copper tape for transformer shielding
« Reply #10 on: June 24, 2020, 11:17:21 AM »
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?

john12ax7

Re: Looking for Copper tape for transformer shielding
« Reply #11 on: June 24, 2020, 06:30:32 PM »
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.

Re: Looking for Copper tape for transformer shielding
« Reply #12 on: June 26, 2020, 04:20:48 PM »
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 ?

abbey road d enfer

Re: Looking for Copper tape for transformer shielding
« Reply #13 on: June 26, 2020, 04:53:23 PM »
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.
Who's right or wrong is irrelevant. What matters is what's right or wrong.
Star ground is for electricians.

Whoops

Re: Looking for Copper tape for transformer shielding
« Reply #14 on: June 26, 2020, 09:27:36 PM »
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

Whoops

Re: Looking for Copper tape for transformer shielding
« Reply #15 on: June 26, 2020, 09:30:04 PM »
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.

this seems to be a pretty good solution


 

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