Question about shielding a ODD shaped plastic enclosure.

[Sir_Ian]

Awhile ago I had a topic about putting something in this enclosure. The enclosure is a gas/brake pedal for a PC racing game.



So I have my ciruit and am ready to put it in, except I need to shield the enclosure.  I've done some reading up on this and it sounds like I can glue aluminum foil in or buy a spray paint that is heavy in Iron.

Now aluminum foil would work fine in a nice cube like enclosure, but mine has ridges and pedals that move up and down and is rather odd shaped. If I was to use aluminum I would most likely have to use a few seperate sheets. Would this be ok? Because the only connection between the sheets would be them touching and the glue holding them together. Do you think I would still get quality shielding with this?

The other option is to spray in this heavy iron spray paint stuff. (Jack Orman had something about it on muzique.com that I read). Has anybody ever used this with good results?

Any other suggestions? Thanks alot.

[brett]

Hi

Do you think I would still get quality shielding with this?

Maybe not.  Aluminium is very reactive with air, and forms a thin, tough, insulating layer of aluminium oxide.

Copper foil would work very well, as long as you put a few dabs of solder between the sheets.  Also, don't forget that you need one (and preferably only one) connection to ground.  That is more difficult to achieve with Al and Fe (difficult to solder) than Cu.
cheers

[Ice-9]

You could try a guitar luthier supply for some of the conductive paint used in guitar control cavities. I'm sure it comes in a brush on as well as a spray on aerosol. With the paint you will get a much better result IMO.

[DougH]

If I was to use aluminum I would most likely have to use a few seperate sheets. Would this be ok? Because the only connection between the sheets would be them touching and the glue holding them together. Do you think I would still get quality shielding with this?

I don't have a lot of experience shielding stuff. But I did shield this one with aluminum foil, cut into strips, and then glued with spray adhesive. It was the only way I could get the foil in the box neatly. I tried it with one big sheet but once it had the adhesive on the back it was nearly impossible to lay it down and smooth it out properly. It was much easier to manage in small strips. It seems to be doing an effective job at shielding- no major noise problems (given that it's an ancient fuzz circuit to begin with). I verified it with my meter that it does make electrical contact with ground along the whole surface. (I had it plugged in and turned on when I installed the lid- and it "popped", reinforcing to me that there was a good ground connection.)

[GibsonGM]

I've used Duro spray adhesive for sticking down heavy Al. foil.  Believe it or not, it stays conductive when dry!  So I've just added pieces around the odd areas, then larger pieces for the main cavity to be shielded.  Testing with a DMM later showed continuity among all the sheets. 
I've done this for guitars and stompboxes with good results.

[petemoore]

Now aluminum foil would work fine in a nice cube like enclosure, but mine has ridges and pedals that move up and down and is rather odd shaped.
  Don't destroy the workpiece of your plan, but have you tried cutting/breaking out some of the internal impediment walls?
   If I was to use aluminum I would most likely have to use a few seperate sheets.
  I used a testclip to attach the aluminum sheet to ground.
  Would this be ok?
  Seems like it might be a bit lumpy and the ground connections could move from point to point. Try working with paper templates and see if you can't get 1 piece to fit in?
Because the only connection between the sheets would be them touching and the glue holding them together.
  Daft, too bad lasange aluminum [available at your frozen food counter] is dangerous to work with.
  I see foil used in commercial pedals, it's always glued to a substrate IIRC, what is the exact thickness [looks like heavy duty cooking foil] and composition of the metal is unknown to me.
  Do you think I would still get quality shielding with this?
  This is the one question that makes all the al-foil shielding either worthwhile or not to me, is a thin sheet of aluminum sufficient shield, I've read: 'it shields', and surmize it shields to some degree, I suppose it depends on what your'e shielding against.
The other option is to spray in this heavy iron spray paint stuff. (Jack Orman had something about it on muzique.com that I read). Has anybody ever used this with good results?
  Major guitar Mfr.'s I believe use some stuff, DIYers test ground planes and get ground connections everywhere...
  Dan-O pedals are low noise and use only a ground plane shield.
 

[Sir_Ian]

Ok, I tried to find some copper tape at a few stores today. Had no luck.

So, I decided to take a risk and I bought some aluminum foil tape at work. Here is a link to the product.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=96372

I just tested it. It works. I laid a couple of strips down on the back of the enclosure. I get continuity everywhere. So thanks to everyone for their ideas....I would have been too dumb to think of the aluminum foil tape. I'm mostly just posting this so that anybody who searches this topic in the future will hopefully come across the information.

so....Aluminum Foil Tape Works!  And it seems to be a much cheaper alternative than some of the other things. The roll only set me back 7 bucks.