Introduction: How to Block Anoying Cell Phone Interference

Picture of How to Block Anoying Cell Phone Interference

This instructable will show you how to block that anoying bleeping interference with radios and speakers when your cellphone connets to the mothership or that rare time when someone is actually calling you.

You will need:
2 cell phones (one to test with and one that causes interfernce)
1 9 inch piece of foil (tear off 9 inchs of foil)
a flat surface to fold foil.

Parental Guidance if needed.

Step 1: Folding the Foil

Picture of Folding the Foil

Place the 9 inch piece of foil on the table.
Place your phone on top of the foil, near the top edge.

Now fold the foil in the middle by bringing the bottom of the foil over the phone. Meet the two jagged edges together and crease the new bottom edge.

See diagram (fold on red dotted line)

Step 2: Making Side Folds

Picture of Making Side Folds

After making the main fold in step 1 we will fold the sides down so the phone doesn't fall out. Note: The phone should be still sandwiched in the middle.

FOLD on first red outside red line. Then FOLD again. Repeat for other end.

Step 3: Finished.

In my tests the foil is sufficient enough to block the signals to your phone that causes interference with stereo equipment and computer speakers. It blocks the signals so well that when someone tries to call you they get a message that you are unavailable! Your phone doesn't even ring! Its like your phone is not even on!


A small wallet sized one may block RFID chips in credit cards/Drivers License

Although I am not condoning illegal activity a larger version can be made to fit a libraray book. It might be enough to block the scanners from reading the RFID tags affixed to library books incase you wanted to take home a reference book.


paul.riley.3781 (author)2015-04-12

What is needed is a filter that blocks those frequencies which I have in my computer setup built in, I don't get interference on my computer setup with receiver, laptop (macbook pro) connected to receiver, 5.1 surround system, iPhone 5.... I don't get interference... My friend however gets massive interference with his Samsung Avant used for tethering to his macbook which is connected to his Samsung (40 inch) television. He is using a cheap HDMI cable that is fifteen feet and was only four dollars on amazon.... The more expensive cables have better insulation from interference but not sure that is the problem. Is it the cheap HDMI cable that lets the cell phone interference in? There is a ham radio RF filter that goes around the cable for about three inches and uses magnets and is about thirty dollars on amazon. I will first try a better HDMI cable....

Mike_JRVD_Toy (author)2014-12-03

Why would I do all this if it blocks my phone from working at all? I could just turn it off for that? But hey, thanks for wasting everyones time with stupid advice.

hitman1689 (author)2011-02-07

so you made an instructable about how to wrap your phone in aluminum foil so that you can't use it? there's an off button for a reason lol

ualjetmech (author)2009-09-10

OK I have one for you guys. I didnt have a cell phone. I live in RURAL area and would still get this sound over the TV, the AM radio, on video cameras, PC speakers, car radio and DVD player~ any explanation for that? Would love to know if the neighbor is trying to listen in with something that would grab cell phone signals? I didnt own a vell phone at the time (about a year ago) ????

Doneitmyself (author)ualjetmech2011-01-10

Sounds like a bug in the house?

captain Jack (author)2009-03-16

my vote - turn it off.

wonderboy (author)2008-07-10

I found a site that has a product that stops cellphone speaker buzz problem. It's call I use them everyday at my desk. No more wacky buzzing noise.

dalbyman (author)wonderboy2009-03-09

that material looks a bit like the anti static bag that a hard drive comes in...?

thematthatter (author)wonderboy2008-07-11

Can you still receive calls? I dont have my razr anymore. Its a long story involving Cingular, The Republic of Korea, and international calling.

wonderboy (author)thematthatter2008-07-11

Yes. I put my pda on what is called the buzz shield and signal is fine. No problems. If I put the phone inside the bag there is a slight degradation of signal. It's amazing.

hondagofast (author)2008-07-13

My Sony Ericsson K550i pings the tower ever two seconds... my crappy GE speakers buzz incessantly.

jtisch (author)hondagofast2008-07-14

I hust turned off the power button on my desktop speakers to eliminate the problem It works. jt

TTSDA (author)2008-06-20

my phone has a " airplane option " that turns the radio part of the phone of but the phone stays turned on. sorry for my bad English [lol]

egreen767 (author)2008-04-25

my stupid razr causes tons of electronic stuff to make weird noises. ill be watching tv and suddenly it starts making a bunch of noise. it actually does it randomly, even when im not getting a call. so, this is a good idea.

thematthatter (author)egreen7672008-04-25

i had a razr, it pings the network like every 15 minutes or so.

atomicrabbit (author)2008-02-29

the only interference with stereo/speaker equipment I've seen with cell phones is when your receive an incoming call. Therefore if you turn the phone off, you will not receive any incoming calls and therefore won't get any interference. GPS will not cause an interference. Also, I'm surprised no one mentioned this, but if you block any signal from your cell phone using foil or faraday cage or anything else that blocks the signal, your cell phone will be trying extra hard to get a signal and therefore drain your battery in a fraction of the time it normally takes for it to drain. So if you leave it in the foil for a long amount of time, you may pull it out just to find out it's dead and need to recharge it.

labeey (author)2007-05-06

easy solution... .WRAP THE SPEAKERS with foil...that way you can still use the cellphone... :)

thematthatter (author)labeey2007-05-07

wrap your head also so cingular wireless wont steal your project ideas :)

Bas (author)thematthatter2007-11-06

That way Professor Xavier can't steal them too.

Weissensteinburg (author)2007-05-04

You could also turn off your phone.

the foil cover is a little quicker than turning the phone off and on. you can also use it while the phone is charging from the computer or transfering music or pictures by the data cable (if so equiped)

eric4435 (author)thematthatter2007-10-21

Good point

Thank You! nobody seemed to realize this

themasterpyro (author)2007-09-09

not being able to use the phone kinda defeats the purpose.

cartufer (author)2007-07-22

i'd just use an anti static bag like hard drives come in, i had a wireless laptop card come in a nice phone sized one once, 1 layer of anti static bags will not kill reception, 3 or 4 will

n0ukf (author)2007-06-04

Foil wrapping the phone will seriously restrict its ability to make and receive calls (as I see "faraday cage" was mentioned). Your speakers themselves likely aren't catching the signal you're hearing, it's more likely the poorly shielded amplifier (whether in PC speakers, or your home stereo or TV). Speakers are a low impedance device and need a strong signal to reproduce sound (thus the need for an amplifier), you're battery powered cell phone doesn't put out enough power to directly drive the speakers even if it were laying against the coil.

dogsrcool2me (author)2007-05-07


A small wallet sized one may block RFID chips in credit cards/Drivers License

Although I am not condoning illegal activity a larger version can be made to fit a libraray book. It might be enough to block the scanners from reading the RFID tags affixed to library books incase you wanted to take home a reference book."

I already did an instructable on this.
RFID secure wallet

great minds must work alike. i didnt steal the idea from you but got the idea from PC world (i think), they were talking about less than honest postal workers zaping RFID tags while Passports/credit cards were still in the envelope. then i made the connection RFID tags>>credit cards>>credit cards pay cellphone bills>>cellphones>>blocking anoying beeping

I wasn't saying you were.

gmjhowe (author)2007-05-05

well, i use my macs built in speakers, and they never seem to interfer, does apple build in some blocking electronic sheilding? cud this be applied to normal speakers?

thematthatter (author)gmjhowe2007-05-07

i think it depends on the quality of the speakers and anything unshielded, it doesnt bother my speakers at home, unless i the phone next to unshelded usb wires. but its real loud with my sisters cheep computer speakers.

lemonie (author)2007-05-05

I have to agree with Weissensteinburg. I leave my phone within earshot, but far enough away from the PC and stereo.

I once picked up a Taxi radio on my stereo, which freaked me at the time.


carpespasm (author)2007-05-05

wouldn't wrapping your phone in a faraday cage also kill it's reception?

genterara (author)2007-05-04

interesting. probably I can now isolate a power source thats inside a speaker.

beavis2k (author)2007-05-04

some phones still transmit signals even when off, usually for localization (gps enabled). Another method is to use the "airplane mode" in the cellphone.
Search for Faraday cage for more info. There is a website that makes a type of fabric for this application lessemf.

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