Circuit Schematics Diagrams and Projects

Simple Cell Phone Jammer

Simple Cell Phone Jammer

Description

A “Cell Jammer” is just way of saying “Dirty Transmitter” which happens to transmit within the Cellular Phone Bands. Reality is, the dirtier the better.

The 555 timer [8 pin] IC simply makes a noise. It’s coupled via C4 [electrolytic] to modulate the MRF transistor oscillator. With C1 set at roughly 1/3rd, you will be close to 900 MHz. By sweeping the C1 trimmer capacitor, you can swing the output frequency from 800 MHz to 2 GHz with the transistor and values shown.

You could replace the 555 chip with an electret microphone and listen to yourself talk on a scanner, so the unit could easily couple as a UHF Bug.

Instead of a single Tapped Coil, I’ve used two molded inductors for ease of construction.Values for C1,C2,L1,L2 are critical for the frequency range.

You might want to build the unit into a metal box, add an on/off switch in the batteries + line, and maybe even add a LED. Connect an old 800 MHz cell phone antenna to C5.

Would you believe the whole thing can be built on top of the 555 IC itself when using surface mount components, and the lot will fit onto a nine volt battery clip. Output is reasonably good, although the current drain is a bit high, so a new 9 Volt battery will only run about an hour, [if you are lucky].

The “Cell Kill Distance” is around 10 – 15 feet, ample for most purposes.

Designer & Author: Special thanks to Laszlo Kirschner.


Comments (113)

kummi
i think its cool and i want to use it as ma project. thanks
safyan
hi can u plz give me the detailed discription of this project i m interested basically in the electronic parts u have used i want their part number.u contact me on my email id i would be really thankful to u i m wating for ur reply
anonymus
hey this is a great circuit. I am using it as an extra project in my electronics class, but i was just wondering if anybody could tell me or direct me to a website that i can learn how to make a 1 and 2.2 nano henry (nh) coils. ty in advance
jude
there is a simple equation for the winding,

Wheeler's Formula (single layer air core coils)
L(uH) = (r^2) * (N^2) / (9*r 10*h)
where:
r = coil radius (inches)
N = number of turns
h = coil height (or length) in inches

found from this site
http://forum.allaboutcircuits.com/showthread.php?t=12870

hope this will help you!
Did this worked ?
ethan
yah it helped me make the coils the right size, but i still cant get it to knock a signal out. can anyone shed some light as to why this is and any way i could make it more powerful?
gerlie
where can i buy the MRF947T1?please email me...thanx!!
Pran
It would been wonderfull if the turns, diameter and the guage of the coils are given for easy construction of an average hobbyist.
kummi
where can i get to buy MRF947T1
Meins321
MRF947T1 = Motorola NPN Low Noise, High Frequency Transistor
Replaced by
PRF947 = Philips Transistor
or
MAS947 = HOPE Microelektronic

I can't find a source, can you help us please?
Farnell?

amar gupta
great project .....
i humbly request you to send the complete information regarding it..........
thanx in advance
my email id : This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Sanjay
hi.... i also likes r&d in this field.... so please contact me on my id ok... i wants some suggesions... good bye
Remi
I read about the topic and it is really interesting
I would like to know that whether the same technique can be used to jam the cable tv Signals
Please reply
Thanks in advance
sandeep
hi sir
i would like to know wehther the above circuit could be used as a effective jammer for freq. used by gsm companies in india & other asian countries.
i would be highly obliged sir if send me the working and detailed scematics of the jammer circuit shown above
thanks
DEV
hi
i am from india this mrf947 tr not avible in marcket plz send equi value of mrf 947
Priyanka
I am not getting MRF947T1 in Kolhapur.Tell me where I can get this transister?
OR tell me replacement to MRF947T1 transister,urgently....
Faisal Mahmood
Im an electronics engineering undergrad student kindly send me the complete details of this project at This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Thanks a lot.
udy
i am a EEE student,please send me full details about this project,... my e-mail id~ This e-mail address is being protected from spambots. You need JavaScript enabled to view it
ankita
i want to use it as my project ,please give me detail.how it work ?,component and price
Charles
Hey i would like to use this as a project for my EE class and would like to know more details; the components i would need and about how much it cost
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
thanks
di
it will be a great help to email me the whole docs about this jammer. fortunately, our project is about jamming and i find this circuit very simple. this is really urgent. pls send me all yhe important details specially the components. thanks alot
Jack Man
I was just wondering if you could e-mail me a list of all the parts you used for this and were i could get them(Radio Shack?) to This e-mail address is being protected from spambots. You need JavaScript enabled to view it Please and Thanks
ragubond
hi..bro...can u pls giv me the details about the project........think me as ur bro...and do dis help contact me : This e-mail address is being protected from spambots. You need JavaScript enabled to view it
r through my no. 9884477652
im not telling you, lol
A zenner diode noise source and a power amplifier system would create emissions all across the band upto 2gz easy. you may even like to try adding some mixers and mix two noise sources together, so you get the sum and difference of both noise generators. Makes me laugh when people keep asking for the info, the circuit is right on the page, what elese could they possibly need. Shows a great level of not understanding the fundimentals of electronics engineering, read the books you forign muppets. Is it just me or is there generaly a high level of incompetance assosiated with forginers. Honestly read some books to understand how the ciruit works, otherwise you will always need somebody to hold your hand and do the work for you.
Anthony Ike
hi i,m a physics undergrad student desperately in need of a few detailed projects,so pls u cud snd me some including this by e mail - This e-mail address is being protected from spambots. You need JavaScript enabled to view it
newbie
Hi, I'm a EEE student. Can you send me the details of this circuit coz I think this is quite good to be a project to do. So, can you send this by e-mail This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Ricardo
Hi, I'm a EEE student. Can you send me the details of this circuit coz I think this is quite good to be a project to do. So, can you send this by e-mail This e-mail address is being protected from spambots. You need JavaScript enabled to view it
DANIEL MOSCOSO
friend that such you can help me????????????

can you give me but characteristics of the source or battery????????

thank you
anson
1. i would like to use this as a project ,plz give me detail.how it work ?
2.mrf947 TRANSITOR not avible in marcket plz send equivalent
rajvir
please send me information related with LC tuned circuit. how much diameter of copper wire and no of turns we have to consider for 1nH and for 2.2nH COIL.
rajvir
if any alternative for this please tell me....if this trimmer frequency set avialable tell me parts number....please ....
tarun
1. pless tell the data sheet of mrf947 or any replacements.
2. dia of inductor coil and no. of turns
tarun
1. pless tell the data sheet of mrf947 or any replacements.
2. dia of inductor coil and no. of turns
plz mail me soon
sonu
hey this 4 indians az im too dont worry if u are unable 2 get this transistor use bfw10/bfw11 fromB.E.L. bharat electronics limited.
any querry mailme at This e-mail address is being protected from spambots. You need JavaScript enabled to view it
(cost of this transistor is just Rs11or12 only now stop crying to b indian
jammer
this looks like the orginal P2JBZ circuit from phonejammer.com do a search
sriharsha
hai this is harsha from kahmmam district i am an ece syudent i lik the project mobile jammer i want to this projct as my mini project which i need to submit to the university as i m belomgimmg to andhrapradesh plz sujjest me the place where can i get that her over plz think of abt my request frns


urs harsha
ali shujaat
hy how r u can u plzz send me the compelete info about this projects on my id that is This e-mail address is being protected from spambots. You need JavaScript enabled to view it
i need to make my final project plzzz help me
Siddharth my id?
Hi there,
i live in india, and am pursuing a project on jamming rf signals.
could u plz be kind enough to send me the circuit details (parts list, and diagrams) to
Siddharth
my id?
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
karthikeyan
i want to know the projegt deatials
karthikeyan
please sent the details to This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Marvin
Does any body made it?? did work??
manny villar
jamming phone signal is cool and very beneficial for our machines so they will not interfere with the frequency which they operate...nice one dude!
Yogesh
I want to know all the details about this project for theory Knowledge. Please refer me the information regarding the same.My e-mail ID is:-
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Thanking you!
Marvin
Hi i, looking your circuit and i noticed that you're using an 555 integer with one source of 9v. Remenber that the 555 uses 5V.
Bene
Marvin, the 555 goes to around 18V!! dont tell some shit here
laila taher
what is the kind and name of modulation for this circuit ,kind and specification of the used antenna ,what is the oscillator circuit elements exactly in this circuit.

laila taher
what is the kind and name of modulation for this circuit ,kind and specification of the used antenna ,what is the oscillator circuit elements exactly in this circuit.pleas i want to have the answear quickly at this email : This e-mail address is being protected from spambots. You need JavaScript enabled to view it

nivi
i want some more details about the circuit and its operation. could you please tell me where we can get the out put
nivi
i want some more details about the circuit and its operation. could you please tell me where we can get the out put . my mail id is This e-mail address is being protected from spambots. You need JavaScript enabled to view it
Physics.Dude
can i get some specifics on… C1 30PF KEY=A 30%
like part #
iron
Hi last night i made the circuit in the multisim, in the output i have like 2uV and -100.5 dB in AC , in DC i have 3.6 V and 25.5dB,is this correct??


does anybody made the circuit and take values in the output??
mayure deep oo5
sir i very thankful you give me cell phone jammer
dayagram & parts list

























This e-mail address is being protected from spambots. You need JavaScript enabled to view it
hi frnds mobile ke bare main
ankit
want to use it as my project ,please give me detail.how it work ?,component and price
romeo
the transistor MRF947T1 is unavailable in our market.... can you name any replacement for this component?? pls help me... tnx..
kumsa
i want about the winding of the coil ,diameter ,gauge to construct
Mains
There is lot of info missing: Part list, how to wind coils, what kind of antenna, replacement part!!
maurice evans
I think there has been some circuit which are able to detect that there are cellphone jammer in the area, have you heard about this guys?
noggonen
Maurice: try googling 'Gestapo'
Ally
Sir I Humbly Ask U To Mail Me All The Components Required To Make This Ckt,The Antenna Type , And A Detailed Explanation Bout The Working And The Components...Please I Would Pay U With My Life for being such A genius... Thank Ya

My Email: This e-mail address is being protected from spambots. You need JavaScript enabled to view it
aaron gray
is there any newer version for this? will it be possible to make this work on wi-fi?
junaid
1. i would like to use this as a project ,plz give me detail.how it work ?
2.mrf947 TRANSITOR not avible in marcket plz send equivalent
kumaresan
can i use MRF547 instead of MRF947
proteek
great friend this ckt really good
we want a jammer that can actually block all mobile & display freq & number of the caller so can u plz help us as we r left with few days for synopsis submision so plz send info as soon as u can
my id is This e-mail address is being protected from spambots. You need JavaScript enabled to view it
plz
thnx
NEEDS HELP
What is a substitution for the transistor in this diagram? It is very hard to find
David
reading the requests here it sounds like a bunch of towelheads looking for something free. They have no idea of american culture and do not care what others think of them!
Dan
how the hell do you want to use BC 547 for this project? http://www.bobtech.ro/document...stori.html here you have a catalog with transistors that are usually very common in any country. if you want to jam a phone that works at 800, 900, 1800, 1900, 2100mhz do not chose a transistor that works at 300mhz maximum... (like BC547)
Omkar
Nice simple circuit. Thanks for it. I am also from India and some are spoiling country's name. If you cannot built such a simple circuit, then what you are you doing in your BE EEE? Calling yourself electronics engineers but not able to build even this. This is final year project lol.

Thank the author for posting a schematic and you cannot expect him to personally send you details which has already been posted here!
ashish jain
can u give me the detailed description of this circuit as i want to use it in my project
Rony
some Indians are really making shamefull act here.. i m also an Indian.LITTLE stupid ones are .simply begging to the author for "more details" wht the hell u want more.? damn he has posed a lot for u here..!! he has given all all the details.. wht else u want him to say .? the fundamentls of electroncis for the stupid little engineers ..? dont spoil the name of INDIA AND STOP ASKING DAMN THINGS LIKE -- HELP ME.. HELP ME.. !!
not a single hell is here form my country who want to take the challenge .? every one want to hv details.. in the mails.. --is the author ur servant .? ass holes.. ask to ur faculties.. abt this.. ask to ur father who is spoiling money for u. .every samistor..ur relly nothing but a BULLSHIT..
NOW KEEP UR MOUTH SHUTTT AND START MAKING THE PROJECT.. work hard and find out form books and books and books..by tht way u will learn..intoi ur shit brain..
hope u all can UNDERSTAND ME.. and dont spoil OUR countries name..!!
--Rony
superb!!!!!
superb!!!!!!!!!!
anderson
i m not getting Transistor MRF 947 from the market,is there any equivalent transistor to this MRF 947
Charles Bronson
Whats the matter wif all dese stupid students - the bloody circuit is there, what more do they want? All foweigners as well.
nabeel
Thank for the Author
I advice the biginers enterested in this project by
the folwoing
use the same circuit to produse 88-108 mhz osillator
and pikup the signal by FM receiver
with BC547 transistor
hence you have chang the inductance
and some capacitance like c2 and use 20 pf
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
nabeel
بسم الله الرحمن الرحيم
انا انصح جميع المبتدئين الهواة الى البدء بالدوئرذات الذبذبة الواطئة
نسبيا مثل 88-108ميكا هيرتز قبل الدء بذبذبات عالية مثل 900 ميكا
وذلك لسببين الاول سهولة التقاط الاشارة المولدة والثانية كسب الخبرة الازمة
للتعامل مع الذبذبات العالية مثل 900ميكا
This e-mail address is being protected from spambots. You need JavaScript enabled to view it
firas
it is soo nice
fortune
hello.everyone,we would like to intruduce ourself ,we are professioan manufacturer of cell phone jammers.if you interested our products ,we would like to get your reply.thanks
rohit
this is great project but,
where can i get to buy MRF947T1
moorthy
how wind the inductor
ajit dhamankar
send me all detail of simple mobile jammer using timer555
Ramana
i need a full details about this project
deepak
hey!
cn v use normal transistor here
gurpreet
sir plz tell me about the mobile jammer components and connection clearly and in detail and plz tell me about the L1 L2 sir plz.............plz.....plz...soonly
niva
whts the replacementfor mrf 947.......bc945 is fine?????????
usa
Here's an idea: you could combine this with a cell phone detector so that the jammer will activate only when cell phones are near it. That will save battery power.
comments
this is a nice project....
and a word to those who got irritated by seeing indians asking for details..(which they think shame 4 the nation)you r free 2 comment.....but should not hurt others..at the least should hav culture in your comments..pls..
Ashar
from where can i get the required devices to make this jammer and how much wil it cost approximately?
Arcisure Engineering
I took a look at the schematic and if im right, this device aint working for blocking a cell phone, because a cell phone has multiple frequency bands. this can bes solved using a 4017 uC, to automaticly change the capaciter value, and so the frequency
majid
hi this is a great circuit. I am using it in my mini project
but i need to know what is the type of the cell phone antenna ......???
pls replay
mikle
heey i cant know about antenna any thing .....
which type ??!!
what is the rang and CDMA or GSM
WaqaR
hey guys.. i hav just made up this project but cant get it to work...

got the exeact values for the inductor..
used bfw10 transistor.. insted of the mrf one...
n yes plzz tell me the detailz abt the antina...
plzzz
Adnan
Hi can i get an alternative to mrf947. Its not available in the market.
alejo
where find mr. Laszlo Kirschner , i need your help about this jammer
Puneet jain
I like it , we make this project
zeeshan
m from pakistan!
u can replace mrf947 with any npn transistor that has max frequency range about 2200Mhz or higher like mrf901, mrf517,
here is a link for a bunch of transistors , but select that one that has freq >2200 Mhz
http://www.datasheetarchive.com/pdf-datasheets/Databooks-2/Book249-5690.html
and also one indian said in this forum to replace it with bfw11
plz dont use that transistor as is has only 1Mhz freq range and also its not an npn transistor

and if any one ask about the detail about this project
plz dont say him as stupid or ant thing else

for those who still wants the detail:
read basic transistor biasing and working articles and little about 555 timer


mustansar
i am electronic engeneering student and i want to know the working of this circuit and hows we can jam all kind frequencies used in mobile phones and jam all kind of phones
santosh
can any one suggest me , were can i get MRF947T1 transistor in hyderabad.....
praveen tripathi
hello sir!which type of antenna i can use in this project;which is easily available in market?please tell me complete name of that antenna,so as i can barrow it from market;
Ali
can anyone please give me some details about the cell phone jammer i wnt to make it as my project
Mexicannn
Wow All of the information needed to build this circuit is here in the text. What other information do you need? its all in the schematic. I am amazed at how many people are baffled by this extremely simple circuit. And yes..... you can get these parts at radio shack. as for the 555 timer any electronics savvy person can locate one.
Phy
Thanks for the schematic. Saved me a day of trial and error experiments. Now I can kill signals when I really -want- them to be killed. Thanks again!
arimardan
i like this project
Adam Eve
For gods sake what the hell is wrong with people: Parts list is there, working of the circuit in there, google the parts list for datasheets, google for 'inductor calculator', why the hell are people so lazy? If you work in R&D, or are at UNIVERSITY doing a degree then you should already know what a varicap (trimmer cap) is, or how to use information in datahsetts to substitute transistors, or how to source a 555 timer, or how it operates as an oscillator.

So what the hell is it all about then? Why are all these people posting their emails on here? Is it a scam? WTF????
Lad
sir,I've done the stimulation and it working.I got 900MHz and above depending on how the capacitor is varied.I choose it as my project and I will be defending it next week.but my supervisor asked me to show him how and which components generates the noise.I thought both the noise and the triangular wave are generated from the 555 timer.I will be very grateful if anyone can help.Thank You.
jeong
Current Gain-bandwidth product of MRF947 is 8GHz (fT=8GHz).
If MRF947 is not available, check fT of Transistor in datasheet.
CHANDRA SEKHAR
Hi can i get an alternative to mrf947. Its not available in the market.
East
http://www.westfloridacomponen...istor.html thats where you can get your mrf947. and if it doesn't ship to where you live just google mrf947.
Basit Ali( This e-mail address is being protected from spambots. You need JavaScript enabled to view it )
m from pakistan....HFA3046, HFA3127, MRF 313 ARE THE BEST REPLACEMENTS AND WILL WORK PRETTY FINE IN SIMULATIONS....AND THE MOST COMMON AVAILABLE AND WORKING TRANSISTOR FOR MRF947 IS 2N5108......AND I M USING 2N25108......
EITHER OF THEM WILL WORK (INSHAALLAH)
I HOPE I HELPED YOU..
hetali
sir i am doing mobile jammer project, and i am not getting 1 IC maxim 2623 can u suggest me from where will i get that IC. and one more thing i have RF and IF section in that circuit diagram which are difficult to design, so can u help me in dat to get that pcb board readymade..
muralirajana
i want know for how much distance it jamm
Fakhrealam
hi i ma telecom student i want to complete my mini project mobile phone jammer so that i kindly request you to help me
arshad multan
thanks very good project
drochalsey
Nicely simple and effective circuit, Laszlo.
Do you (or anyone else, for that matter) happen to have any suggestion for interfacing it (the circuit) with US, 110-120v AC, house current, as a "current subcarrier transmitter" so that I can turn the "hot" line in my whole house into one big (short range) cell-phone-killing antennæ (i.e.: turn my house into a "cell phone NO-FLY Zone?")
I'm not worried about the neighbors as the signal will NOT carry (RF-wise) to their houses, NOR will it be able to go past the "isolation transformer" on the pole.
Thanks in advance,
drochalsey (a.k.a.: This e-mail address is being protected from spambots. You need JavaScript enabled to view it )

Write comment


busy