Completely isolating a mobile phone

Try putting it into a microwave oven. Just don't turn on the oven. :)

That destroyed the phone, not stopping signals to reach it! :)

-- @~@ You have the right to remain silent. / v \ Simplicity is Beauty! /( _ )\ May the Force and farces be with you! ^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3 ???! ???! ???! ???! ???! ???! ????? (CSSA):

^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Please read what I wrote again for context.

=B4=E4=BA=A4! =E4=B8=8D=E6=89=93=E4=BA=A4! =E4=B8=8D=E6=89=93=E5=8A=AB! =E4= =B8=8D=E8=87=AA=E6=AE=BA! =E8=AB=8B=E8=80=83=E6=85=AE=E7=B6=9C=E6=8F=B4 (CS= SA):

Dear Troller,

Wrap in two layers of 1 inch wide copper tape with conductive adhesive from 3M Corp. Competely enclose.

etc...

I could also do the necessary math to see how much isolation is required, but since you didn't supply any details, I won't bother to try.

Did you put anything over the open end of the tin can?

Because aluminum is known to block the government mind control rays that are forcing you to post such drivel. With an aluminum foil hat, you will be safe from cell phone radiation and mind control rays.

Putting head in microwave oven is more permanent cure for mind control rays.

Had to test it :) In a tin can (tea can 2x2x3") fully closed: no reception Overlapping lid only 2 mm open: reception Microwave: no reception

Tony

Try a 2.4GHz cordless phone in the microwave oven. Punch the "find handset" button on the base unit. The isolation of the oven is usually insufficient and the phone will ring.

Let's run the numbers. A microwave oven belches about 1000 watts of RF. The leakage spec is very roughly about 4 mw. 10 log (1000 / 4*10-3) = 54 dB isolation

In a strong signal area, the local cell site will probably produce about -80dBm. (I cheated and just used the test mode on my cell phone to get the number). The minimum sensitivity for the cell phone is about -102dBm. In order to stop the phone from ringing, you need only about 22dB of isolation. Since the microwave oven shielding is 32dB better, which is 1400 times better, the microwave oven does quite well at blocking cell phone signals.

However, the cordless phone is another story. The base transmitter puts out about 10 mw into a really crappy 1/4 wave antenna, which will product about -20dBm at the handset (with lots of assumptions that I don't want to get into). The handset has a sensitivity of about

-104dBm, requiring an isolation of 84 dB to completely block the signal. That's 30dB or 1000 times more than the 54 dB that the microwave oven shielding can provide, so the cordless phone rings.

Note: All the numbers I supplied are bad guesses and are probably wrong. However, since the isolation difference is 1000 times, it's highly improbably that my numbers are in error by a factor of 1000. If you have better numbers, that's fine, but the results will be the same. The cordless phone will ring, and the cell phone will not.

He'll need to overcome the safety cut-out that the government requires to be installed to prevent people escaping mind-control rays that way.

Sylvia.

On 17/08/2011 12:50 PM, Jeff Liebermann wrote: [snip]

Sounds correct. I have a 5.8GHz cordless. It rings when in the microwave:) Maybe someone can test a 2.4 one?

Thanks. Very detailed...

Sorry for missing the last part and for my first impression about an oven (always used to cook things).

OH well, I don't use microwave oven. It's too dangerous. :)

I see...

-- @~@ You have the right to remain silent. / v \ Simplicity is Beauty! /( _ )\ May the Force and farces be with you! ^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3 ???! ???! ???! ???! ???! ???! ????? (CSSA):

Do I need to ground the packing?

Looking up "copper tape" in Amazon, expensive stuff! :)

-- @~@ You have the right to remain silent. / v \ Simplicity is Beauty! /( _ )\ May the Force and farces be with you! ^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3 ???! ???! ???! ???! ???! ???! ????? (CSSA):

Could I use the bags for potato chips? How many?

-- @~@ You have the right to remain silent. / v \ Simplicity is Beauty! /( _ )\ May the Force and farces be with you! ^ ^ (x86_64 Ubuntu 9.10) Linux 2.6.39.3 ???! ???! ???! ???! ???! ???! ????? (CSSA):

I wonder whether an Al hat could stop psychic attacks? Psychic attacks and/or magic are EM-waves as well?

Some TV drama showed someone jamming plastic forks in the interlock catch slots so it worked with the door open - failing that, anyone posting on a sci.electronics group should have the knowhow to solder a mains lead directly to the transformer tags.

Yes, but only if I get all the potato chips. I prefer the overpriced non-greasy rice based salt and pepper kettle fried variety. Send to address below.

One bag holds about 240g of chips.

Some of the companies I previously listed sell a fancy aluminum and plastic bag, with a wire mesh view port, and built in foil gloves. It is possible to tune a radio or pager in such a bag, but it's probably awkward. Sorry, but I don't recall the company and didn't find anything with Google.