Have annoying noise?... want a diy shield... try this one.

[destroyer X]

When we produce a very compact amplifier, transformer is assembled near the amplifiers...this will represent noise pick up from transformer in the mains frequency.

So, better to shield using Steel, the one that can produce oxide, do not use stainless steel!

The thickness is important...the biggest the thickness, the best will be... 2 milimeters is good, and the minimum may be the automobile roof thickness.

Cut metal steel the way i am showing in the sketch, and construct a cover.... yes, you can find some junk that can do the same job for you...remember to insulate with rubber to fix using pression against the transformer...as electrical connections may be worst than the insulated shield...you may try both ways.

You can sand, solder sides, and make small diameter holes to keep away from heat.... 2 milimeters diameter maximum holes to air refrigeration...but better not to point the holes to boards and input plugs...you can DIWA.... Do it with aid, and send the box to a chromium finishment or some electrical treatment, or painting it...well, this depends on you.

To avoid hum.... do not run wires in parallel....cross them and keep AC wires distant from audio cables.

Star ground is wonderfull, and thick ground bars are good too.

This box is a hum killer, and using it you will construct compact amplifiers without problems

There is the Mu metal...but expensive and hard to find in the correct size.

I had bad results with aluminium to low frequency...it can work better with radio frequency than to low audio frequencies as main frequency.

Good luck...i already did it many times and worked fine.

regards,

Carlos

[MikeB]

Why not stainless steel ?

Mike

[dtrif]

When we produce a very compact amplifier,

You mean something like this?

[PMA]

You seem to be a real designer GURU Carlos. One could hardly find any field of electronic task unaffected by your valuable advice.

[destroyer X]

do not work with magnets...but you can have magnetic action in the opposed side related your magnet.

If you find a lighweigth piece of metal, some magnetic metal...and you will atract it, having inox as a shield....make this test.... magnet to not stay "glued" into the inox blade...but the metal piece will be...this seems to me that magnetic field crossed the Inox...so...not good to insulate magnetic fields.

bye Michael
............................................

Dimitri Trifanopoulos, was inspired on you that i decide to publish this "shield can"

regards Dimitris
.............................................

PMA, many thanks, but i am having enormous problems to fix one of my Home audio Systems...one Panasonic.

Also i use to burn a lot of parts,i use to invert polarity and i have small theorical know how....no conditions to be a Gurú.

But i have the intention to be some kind of Gurú candidate, but to beginners.... basic electronics, how to design amplifier, how to shield, those things, very basic, that can be good to young boys.

Because they turn happy with small things Pavel, everything you inform to them is wonderfull, as they do not know those things...but be a Gurú to 20 thousand experienced guys is too much to me, i cannot polish the shoes of more than hundred guys.

Good to have you with me PMA.... this was great from you... had confidence, this is fine.

regards,

Carlos

[rabbitz]

Originally posted by MikeB
Why not stainless steel ?

Mike

Austenitic Steel which doesn't magnetise if my old memory serves me.

[wintermute]

I made a sheild out of lead (thought that because it was dense it would work well) It does cut down on the noise induced into my amp but doesn't eliminate it (but then what's left might not be coming from the torroidal....) I know I have been chasing it for years.....

might be time to try steel

Tony.

[destroyer X]

model, to produce the shape needed.... accept easy finishment, with steel brush, can be soldered, and can receive paint too.

I think is a very nice idea.

regards,

Carlos

[wintermute]

mine was a little more crude than that I cut a round piece (at least I think it was round) and then cut slits to fold into the shape that would fit over my toroid. Then used a butane torch to melt solder along the slits to seal it..... next time I have the amp open (could be a while after my last disastrous foray!!!) I'll take a picture

Tony.

[zlast]

I used a piece of steel equal to the depth of my amplifier case, bent into a half circle (see pic). Another use besides shielding is you can keep much of the wiring INSIDE the transformer shielding case. This helps to make wiring and the project in general a bit neater.