Instructables

How To Create Your Signal Jammer

Picture of How To Create Your Signal Jammer
For a long-long time many people were looking for this cool recipe of making something interesting for yourself. And I was one of them until last days. In my quest I came across the Jammer Store blog post called How To Make Your Cell Phone Jammer: DIY Guide. It inspired me to make something like that by myself.

All necessary info, schemes and pictures are there, so I tried. The result is represented in this humble guide for you.
 
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Step 1: The Basics

Picture of The Basics

This signal jammer uses 800MHz frequency to operate because many cell phones are working on the same frequency. So I chose the sweeping oscillator as my VCO. It is really efficient yet may be difficult to use if you are beginner without some semi-professional RF-testing tools.

The clock oscillator (45MHz) is driving a local oscillator port as my noise source and is located on the mixer of the mini circuit. To equate the impedance of a clock oscillator with the mixer there is an impedance matching network. Local oscillator signal goes through this network and impedance is matched.

The 800MHz antenna from the old cell phone is connected to the RF input (mixer port). The RF output then goes to the amplifier located on the mini circuit. The amplifier will increase produced output by 15-16dbm of pure power. The empowered signal is going to another old phone antenna.

Step 2: Your Jammer Works!

Picture of Your Jammer Works!
GSM800 cell phones have their frequencies separated by 45MHz exactly. So when any cell phone tries to make a call - it becomes blocked by itself! The phone talker will hear its own voice.

You can also keep in mind that this cell phone signal jammer can block all cell-based trackers which use your car GPS to track you down and record the data. Even IEDs are probably could be jammed, at least those ones controlled by cell signals.
shiaulteyr2 years ago
Swapping out the sweeping oscillator with one from the phone itself, an old router - if you're interested in those bands - and other electronics (such as old RC toys, which makes those crack-of-dawn RC plane enthusiasts quite down nicely) should work with this design too. That is, in theory at least. Great project to experiment with though!! Good work!

Just on the IED topic there - we used to use a similar device in Afghanistan when the opportunity presented itself and I know that many Police agencies have them in their arsenal - where they provide, I'm sure, much more use than they did for us! (By the time you find out it's a cellular triggered device, you're probably already picking up what's left of it after it went off the day before! Not to mention, setting the phone's alarm as a backup/failsafe is immune to jamming - as are grenades).
and i hate to say / type this. depending on the phone. the alarms wil still go off even if its in stand by mode. then depending on the phones battery, it can be in stand by for up to a week. if u want it to last longer put in a small solar panel.
BearGrills (author)  shiaulteyr2 years ago
Thank you for nice words and advices! It is pleasant to know that similar devices are saving lives out there :)
Shajeel1 month ago

mere baaaaaap circuite tou dikha de kam se kam

zarmons2 months ago

hi you there.can you send me a schematic diagram and the component part? my email zarmons_613@yahoo.com.i like you project and i want to make like this kind of project.

thanks adnvance

zarmons....

nicostar2311 months ago
I want to make one that will crash everything in my school. What should the output(s) be?
if u go that route. u can be branded as a terrorist. because u never kno who might have a pace maker 4 thier heart.
badsting8 months ago
Where should I get old phone and which best MHz ?
try dx. com an or alibaba.com then try many pawn stores . uill sure to find 1 yr looking 4.
hiyer1 year ago
hey i want to make signal jammer as my project . so can you pls send me the list of compenents and the procedure to my email id i.e hvignesh91@yahoo.com
kcrow11 hiyer6 months ago
the list of components ins written clearly in the circuit diagram....open it and you will see! the procedure on building one of these is what the entire instructable is written about, read the article before asking questions.
bro if sm1 hs send u the list of ths component plz send me also
my email id iz saber.shafi@yahoo.in
helo bro
can you help me make a jammer if you want plz sent me all component and detail on my email bilaljarral302@gmail.com,
i hope u help me
if you cant figure it out from the circuit posted above, you have no business tinkering with such things...one could really hurt themselves from electrocution! all the components are listed in the circuit schematic and all the help you need is written in the instructable.
bro if sm1 hs send u the list of ths component plz send me also
my email id iz saber.shafi@yahoo.in
BearGrills (author)  bilaljarral1 year ago
There is no need to write few times, don't clog the comments please
rahul baghel7 months ago
rg
erotologue7 months ago
Hello BearGrills,
I planning to built this jammer but I would like to increase is range ( I'm not talking about the antenna ), how could I do ? does it need another amp ?
is there any modifications to be done to circuit diagram ? . My email id is slugha_432@hotmail.com
paddys0118 months ago
Wonderful project - can anyone tell me if this would allow FM radio signals to be received whilst blocking phone signal?
adithya.yuri8 months ago
Hello Bear Grilles,
I am very interested in this project and In the picture of your model I found a transistor but I dont find any in the circuit diagram , is there any modifications to be done to circuit diagram . My email id is adithya.yuri@gmail.com
http://www.arrl.org/news/fcc-issues-two-forfeiture-notices-for-cell-phone-jamming
Hello Bear Grilles,
I made an account just to ask, can you end me super detailed instructions as well as what each component's function is, I have no idea what I am doing whatsoever, but would love a quick lesson on it. My email is EArmendariz000@gmail.com
soundman641 year ago
Hi BearGrills,
Interesting jammer idea that - getting the received frequency to generate a jamming signal 45MHz offset from it. In your experience, can you tell us how effective it has been in practice? The receive and transmit antennas are quite close. So, I was wondering if the strong transmitting antenna signal would overload the receiving signal and mess the whole thing up (even though they are 45MHz apart)?
Would you not need to filter the receive signal to keep the transmit signal away from it?
Also, it probably wont block one-way text messages being sent from those accursed GPS tracking thingies, will it?

Thanks.
dinodhayal1 year ago
hi sir/madam,
can you help me make a jammer if you want plz sent me all component and detail on my email skddinesh295@gmail.com,
i hope u help me
dinodhayal1 year ago
an you help me make a jammer if you want plz sent me all component and detail on my email skddinesh295@gmail.com,
i hope u help me
mammasboy1 year ago
this is an awesome idea, could you provide a parts list and a "how to" for the circuitry side of things? i'd love to make one of these
JFaust781 year ago
I am not a professional electronics guy, but could someone suggest a part number or link for the clock oscillator. I am finding many of them, but do not know which would work for sure. Thank you so much for the great post!
sumalyo1 year ago
very very very very gooooooooooooooooood
i want make a mobile jammer plz help me
BearGrills (author)  bilaljarral1 year ago
All details are here in this DIY, use it and make your jammer ;)
hi bro can you send me all component from your project to my email kukuhmoeslim@gmail.com thank you so much. i hope you can help me please....
BearGrills (author)  kukuhmoeslim1 year ago
Hi!

Sorry, but I can't remember all components now because it was long ago when I made my jammer. Just follow the instructions I wrote here and pick up similar components because you'll need to test their compatibility anyway.
fegundez12 years ago
as it has been widely known that most cowardly ied device users do use cell phones to trigger their devices it boggles the mind to think that the military doesn't use some kind of device like this to stop some of the carnage.
No doubt the US military has counter measures. most likely developed before other departments of the US government empowered terrorists the US was friendly with the the nut & bolts of IED. Frankly while I understand why the use of IED is characterized as cowardly, I don't agree with that assessment even though they are being us against US soldiers. Those employing the IED are are in their own country are friendly to that country, and are using them against an occupying force. The use of the IED is no more cowardly than a pilot dropping bomb from the safety of miles above or person sitting at a console in the us commanding a UAV to fire a missile. In the event the roles where reversed Americans would do the same to any army that dared to enter the US. IMO it's going to be the unhealthy narcissism of Americans that will be our ultimate down fall.
The jamming of radio signals by the US government and/or military is old news. No reason to think they are not doing so now.
JKR fegundez12 years ago
In both Afganistan and Iraq the coalition forces use a very complex jamming system that jams multiple frequencies. Look up JCCS-1 and the CREW system. The Army just brought back an MOS in Electronic Warfare from lessons learned in country. I spent a year in Iraq installing and maintaining CREW systems, cool stuff to work with most of it was classiified secret..
BearGrills (author)  fegundez12 years ago
Actually they do use very powerful and completely reliable jammers for disrupting IEDs. The post about it you can find at the Wired.com's Dangerroom, the Iraq invisible war or something like that.
static2 years ago
When I read microstrip line on the schematic, I had something else in mind, that I was seeing it on the most predominate photo of the completed board, I assume here microstrip line means the small coaxial cable.
pcooper2 static2 years ago
No, a microstrip is a strip of conductive material isolated from a circuit board ground plane by a layer of insulating material (dielectric). The characteristic impedance of a microstrip depends on the dielectric constant, the thickness of the insulator and the width of the conductor and is chosen to match the output impedance of the driver for optimum power transfer. In effect, a microstrip functions much like a coaxial cable.

Connections to microstrip transmission lines are usually made with surface-mount components, since a PCB feed-through hole would introduce an impedance discontinuity that would alter the characteristic impedance and cause ringing and unwanted electromagnetic radiation. The circuit board depicted in this project is constructed almost entirely using microstrip design techniques.
static pcooper22 years ago
Yes I understand what you mean how strip lines are use at the frequencies in construction, now you brought it up. I was unfamiliar with what was used on the schematic to depict the strip lines. For me anyway it was difficult to follow the photos of the populated board.
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