I'm looking to build a faraday cage for a home electronics projects. I was thinking about doing some brazing with copper sheets after seeing some of the links in the forum, but then I thought it might be a whole lot simpler to just get a large used aluminum stock pot, the kind that restaurants use to make big batches of chicken stock. Just clamp the lid down and ground the thing and I should be good to go.
the best faraday cage and probably the easiest is to get some 2x4's and brass mesh sheets. Mythbusters did a few episodes using this. make a box frame with the 2x4's and staple the brass mesh to the outside. fashion a door within the frame (with hinges installed before attaching the brass) and then cut out the door after you attach the brass. Solder a ground wire to one of the corners and ground the cage.
I'm not sure how cheap the brass is, but it shouldnt be too expensive. Unless you already have the aluminum sheeting (or can find some for free) I'd go with the brass. That way you can see in to the box (or out of it if you are inside.)
What is the Faraday cage FOR??? Just a flat sheet of aluminum foil will act as a pretty good Faraday cage. The foil will short out the e-field of any EM waves with wavelengths longer than the VHF range. A better version is two big sheets of foil held parallel, with a few inches between. That gives you roughly 95% shielding. (Adding the walls only improves things a small amount, from 95% to close to 100%.
Also note that mesh or sheet metal only shields magnetic fields if the frequency is up in the RF range. To stop 60Hz magnetic fields, you need some iron, or some slabs of very thick copper.
I ended up cutting a large circle out of the top of a holiday cookie tin. I soldered a layer of aluminum door/window mesh to the top so that sound could get through. I wanted it fairly durable, so the cookie tin's structure worked pretty well for that. It seemed to work fairly well. The purpose was to try to block out radio waves from a device in the tin that might be able to pick them up. It was sort of a control in an experiment that I was doing.
I've seen Faraday cages built as if using chicken wire (not the same material, but I'm talking about the pattern of course). It would seriously limit the costs of a homebuilt Faraday cage, as well would it provide visibility and so on.
Is it true that one could go with it like this, and how big could the hole's be at max? Or can one use just wires vertically and none horizontally?
If one could use just wiring, one could more easily 'hide' that a room is protected against outside electromagnetic radiation.
I think a cage made of wires rather than a mesh should work; I remember the Boston Science Museum's electricity display was surrounded by vertical cables, and the operator sat in a birdcage-like enclosure. There may have been some horizontal rings on the cage (like an actual, old-fashioned birdcage), but not too many. All the bars on the cage met at the top, and I assume they were all electrically connected at the bottom as well.
It's probably been more than twenty years since I've seen it, however, so my memory may be faulty.
Stokes, that cage may have been effective against sparks, and would block low frequency radio energy, it wouldn't be useful in the VHF/UHF/SHF range that most modern electronics use.
The stock pot would be fine, if the entire experiment can fit inside with no penetrations. You'll need to take special care with shielding the lid though, since aluminum oxide isn't conductive, and bare aluminum oxidizes almost immediately upon exposure to air. So your entire lid seal will be a gap. (Silver oxide is conductive, which is why quality RF components are silver-plated.) An aggressive acid flux may let you solder copper finger-stock along the edge of the lid, which could then mate to more soldered-on copper on the base of the pot.
For building your own, copper mesh is fairly affordable. Check the clay modeling section of the craft store, where various metal meshes are available for supporting and reinforcing models.
Mesh has the advantage of allowing light through, so you can read instruments inside the cage, or communicate (IrDA!) with an experiment in progress. Even move a little bit of power, with photovoltaics. ;)
However you build it, you need to give it a low-impedance path to ground. Otherwise the whole cage is just one plate of a capacitor and will happily re-radiate whatever hits it.(*) Because of the skin effect, fine-stranded braid or wide flat strip is more effective than a solid or coarse-stranded conductor of the same cross-sectional area. RF grounds are their own field of study.
(*) I'm not on very firm footing there. If any physicists or RF engineers would like to elaborate on grounding's impact on shielding, I'm sure the thread could use it. :)
So if I understand correctly, if I want proper shielding against electromagnetic radiation, I would need to completely cover the inside(/outside) of a room without leaving any walls/ceiling/flooring out and ground it by for example plugging it into the ground plug of a wall outlet (not using the electricity part of course) when it regards to a room that is not close to the ground.
Is there any way to 'test' the room for efficiency? Maybe by using a cellphone and checking the reception? Radio's and so on?
I would not trust the ground plug of an electrical outlet. A whole lot of oddness can happen to house wiring over the years. For an ideal cage it should be grounded to it's own grounding rod, driven into the ground as near to the room as possible.
As for testing, I would think that any old AM/FM radio, along with a cheap short wave receiver and a low end police scanner would cover a broad enough range to let you know what's going on.
Sorry to confirm, but aluminum foil would stop electromagnetic radiation, radio waves, all that electrical waste? Because there's this guy that builds Faraday cages for hospitals and so on, he has a special copper tape that's designed to have excellent shielding capabilities. It's very thin as well, he names it amucor. Problem is, the stuff costs about 70usd per M².