Hello Rohan, On Wed, 2012-10-10 at 15:47 +1100, Rohan McLeod wrote:
Trent W. Buck wrote:
Since nobody has suggested it before -- why don't you just remove the battery, so that the device is unpowered? Most RF equipment is effectively unreachable without a power source. Problem is that while quicker than 'booting-down'(also glacial); it is a bit fiddly; I want a quick,simple, certain way of shutting it up ! may even upset the phone......phones have feelings to :-) ; I joke ! no flames or digressions into machine consciousness please ! ; anyway the main reason is to avoid the long boot-up; but thanks Trent and others for the many ideas; regards Rohan McLeod
This thread has gone on while I have needed meatspace time. You do need a faraday cage, yes, but you need to understand how it works. It shorts the electric field component of the electromagnetic radiation, but needs sufficient thickness of conductive material. The issue is "sealing" the joints. Since it is difficult to get a good electrical contact, you can end up with an excellent waveguide that will "leak" signal. The way the microwave oven gets around that is a controlled gap where the door shuts into the oven cavity. By carefully controlling the width of the gap, and the length, you end up with the right electrical characteristics at the inner boundary. With the multiple frequencies for a mobile, a labyrinth seal that may have effective waveguides in parts, but discontinuous, should be effective. To make one, you could have a basic sheetmetal box, but soldered around the fixed seams, and then a similar box fitting over as a lid. With a thin sheet of adhesive plastic film to insulate them from one another, you can put the mobile in the box and put the lid on, and have it effectively shielded from the outside radio environment. The other material is 'muMetal", or radio metal, which impedes the magnetic component. I know of it, but not enough details to hand. You might find details on wikipedia, or such. There were other comments, and it might be worth while keeping an eye out on what is on offer. My mobiles were initially secondhand, a Motorola, then a Nokia, but then bough new, but as prepaid items, with the current one I never used the prepaid SIM card, just put in my Telstra postpaid SIM. They expect you to pay for the prepaid phone by using it on their network as prepaid, but you can use on the same network with the postpaid SIM. I type this with consideration of wanting a basic phone, but that the current phones are almost all so much more. Regards, Mark Trickett