The metal trash will help, if the lid fits very tightly and no other gaps/holes exist. Lining the inside of a metal can with cardboard will offer no additional protection. Fully covering electronics inside with heavy aluminum foil will offer considerable additional protection however.
EMP (electro magnetic pulse) induces an electrical current in electronic circuits and exposed unprotected wiring that in some cases is strong enough to burn them out.
You protect devices by shielding them completely with something capable of conducting electrical current, like heavy aluminum or copper sheeting/foil. This metal shielding shorts out the EMP wave (in layman's terms), before it can get to your critical electronics.
Thanks. I was wondering what the devil it would matter regarding the card board. I have an old micro wave and a metal trash can, so I’ll just wrap everything really well in 2 layers of foil and put it in one or the other-things that I don’t use all the time.
The cardboard, or any insulating material, is very important in a home-made EMP Faraday shielding box. It keeps the electronics from touching the outer shell, especially if the electronics are wrapped in foil.
The EMP charge flows on the outside of the Faraday cage/box to ground or it just dissipates. Grounding the trash can is preferred. The cardboard keeps the shell from touching the stuff inside. Styrofoam or bubblewrap do the same thing.
I use a used metal file cabinet instead of a trash can. Looks good and I got it for $40
It also makes access easier by having drawers. It is grounded to my lightning rod system.
I would think that a gallon aluminum paint bucket in the microwave would be just the ticket. Seal it down with a hammer and use crumpled baggies around the cell phones to keep them away from the walls of the paint can.
Most paint cans have a plastic coating on the inside and that might contribute to the protection.
A non-conductive lining is essential; cage contents must not come in conductive contact with the metal cage material itself.