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Cell Phone Detector

Project Summary

This is a mobile phone sniffer circuit that can detect the signals being used in the GSM (Global System for Mobile Communication) band at about 900 MHz. Since the signals are digitally encoded, it can detect only the signal activity, not the speech or the message contents. A headphone is used to hear the detected signals.

Project Description

The circuit schematic is given in the .rar archive attachment. There are two separate detector units. Every detector unit consists of a dipole antenna, a choke and a diode. The antenna receives the GSM signals in media. Then a small amount of charge is induced in the choke. The diode demodulates the signal and finishes detecting. The diodes must be schottky diodes or germanium diodes. Since the forward voltage of a silisium diode is high, it won’t give a sufficient result in this circuit.

LM358 amplifies the received signal. It contains two separate op-amps that are supplied by a common power source. R3 and R7 resistors determine the gain of the amplifiers. When the resistor values are greater than 10M then the noise level increases. If they are small like about 100k, this time it becomes harder to hear the signal.

The PCB file is provided in pdf format. You can apply it to the board by using the ironing method.

R1, R5 : 100K 1/4W Resistor
R2, R6 : 1k 1/4W Resistor
R3, R7 : 8.2M 1/4W Resistor
R4, R8 : 220 Ohm 1/4W Resistor
R9 : 2.2K 1/4W Resistor
D1, D2 : BAT43 Schottky Diode
C1, C2, C4 : 100nF Polyester Capacitor
C3 : 100uF 16V Electrolytic Capacitor
L1, L2 : See Text
U1 : LM358
J1 : 8 Pin Socket
J2 : Stereo JAck
1 × 9V Battery
1 × 9V Battery Socket
1 x LED
1 x On/Off Switch

Figure:1

Figure 1 

The diodes, gain of the amplifiers and the length of the antenna is critical in this circuit. Calculating the length of the antenna is simple. The formulation is given below.

λ=c/f = (300.000km/h)/900MHz =33.3 cm Then; Antenna Length = λ / 2 = 16.6 cm

So there are four pieces of antenna and each one is about 8.3 cm long. The wire type is not critical but its better to choose a fairly thick wire that will not bend too easily. It is a 1.5 mm diameter wire seen in the photo that we used. The two antennas must be positioned perpendicularly.

Figure:2

Figure 2 

The chokes are 10 turn molded chokes. The wire diameter should be about 0.5 – 06 mm and wound around a 5 mm cylindrical object.

Diodes are very critical. You should use one of BAT43, BAT45, AA112, AA116 or AA119. When a silisium diode is used the circuit also works but the detecting area becomes very very narrow.

Y.Erol

Project Files

File NameFile Size
Schematic and PCB layouts192.71 KB
Tags: cell phone, detector

Comments on this Project:

By Stainless 1Score: 

5 years ago:  Would it be possible to use this to triangulate a signal? Could you use it to figure out who's texting in your class or something like that?

By siddharth 0Score: 

5 years ago:  can you suggest any other antenna for this project ?

By parveen kumar -1Score: 

5 years ago:  how can take results from this circuit and can we hear that particular detected signal by this circuit at the same time

By Donny 0Score: 

5 years ago:  Is there a possibility to get a more detailed discription on the circuitry operation to my email?

By Gurumoorthy 0Score: 

5 years ago:  sir,
i'm in a need of mobile circuit diagram for my project... so, can you please send some sites to find those circuits... especially nokia circuits....
Thanking you....
K.Gurumoorthy

By Jahid 1Score: 

5 years ago:  Sir,
cell phone detector can cover only 1meter .Please can u suggest me how i can increase the covering area.I will be thankful if u please give me the suggestion.

By john 0Score: 

5 years ago:  Hi jahid did you use a schottky diode or any other popular ordinary one?

By Ramesh 0Score: 

5 years ago:  Sir,
cell phone detector can cover only 1meter .Please can u suggest me how i can increase the covering area.I will be thankful if u please give me the suggestion.

By Aneesh 0Score: 

5 years ago:  Hi,
Iam a student doing Btech project. Please give me a valid mobile detection circuit to detect the mobiles in the standby mode.

By Hari 0Score: 

5 years ago:  hello,

Can you please suggest me a mobile sniffer circuit when the mobiles are in standby mode. Its very urgent

By tiray 0Score: 

5 years ago:  where can we buy the circuit board?

By SAm ????????????? 0Score: 

5 years ago:  Plz give information about detaches Mobile No. and caller no. and reciver no.

By muthuraman 0Score: 

5 years ago:  Is there a possibility to get a more detailed discription on the circuitry operation to my email? please i am doing this as my college project so kindly send more detail on this circuit thank you

By HSHJS 0Score: 

5 years ago:  how can i detect a cell phone in standby mode .can you email me if you know

By shaunak 0Score: 

5 years ago:  could u plz give me the values of inductor...

By Rishi 0Score: 

5 years ago:  if we use schottky diodes then what is the range of operation?

By Andrew 0Score: 

5 years ago:  Thank you
I was about half way through designing something very similar using almost the same components.
once again
Thanks

By Ghulam Abbas & Osama Ahmed 0Score: 

5 years ago:  Hi! We are students of Electrical Engineering and we made ur cell phone detector as our project I m happy that its working actually we couldnt find diodes u mension se its range is very small could u please tell us any other diodes which can enhance its range Thank U

By muthuraman 2Score: 

5 years ago:  Hi,
Iam a student doing project. Please give me a valid mobile detection circuit to detect the mobiles in the standby mode.
Is there a possibility to get a more detailed discription on the circuitry operation to my email? please i am doing this as my college project so kindly send more detail on this circuit thank you

By Abdul Khaliq 0Score: 

5 years ago:  hi
i want to ask,what modification will b needed if i want to make this circuit change into a radar,and i can see the exact location of cell fone on the radar screen????

By SRJ 0Score: 

5 years ago:  Well, i also want to ask,what modification will b needed if i need to detect the postion of the cell phone. Glad if you could reply!

By sara 0Score: 

5 years ago:  hello,
i'm in a need of mobile circuit diagram for my project . please send some sites to find those circuits...

By sharad 0Score: 

5 years ago:  sir. i'm finding it difficult to get the output from this circuit.. please suggest me operating details..

By chitra 0Score: 

5 years ago:  i need to know the exact operation of this circuit ..kindly mail it to me ..

By raghu 0Score: 

5 years ago:  Sir, I had tried your mobile detector project , but it detect only when the call was comming. I want project to detect the mobile even call not comming. please send the circuit diagram

By circuit_hacker 0Score: 

5 years ago:  This is a diode-based version of a 1920s crystal radio circuit and the same warnings apply: It can pick up ANY strong RF signal nearby. I wouldn't place my hopes in this circuit's working as advertised except when it is held *next* to a GSM phone -- it needs a strong signal to work. If you're standing in the near field of an AM station it will probably pick that up, too.

By maulik 0Score: 

5 years ago:  give me circuit diagram

By archana 0Score: 

5 years ago:  sir,
i am a student of electonics and communication engineering 3 year.i took cellphone detector as my mini project.will this circuit work???
what is the value of the inductance we should use,would u suggest anyother circuit instead?

By garylui 0Score: 

5 years ago:  may i know the circuit the out put is the LED ligth up???
if u detected signal then the out is what???

By Ramesh 0Score: 

5 years ago:  Sir,
I tried my best but not succedded yet in getting the output. can u plz tell me fm vr i cd get hw model of the cct at what cost rply urgent

By GOGILAVANAN 0Score: 

5 years ago:  CAN YOU FET ME WITH THE FULL DETAILS OF THIS PROJECT?

By freddie hubalde 0Score: 

5 years ago:  What is the maximum distance that this circuit can detect cellphone signals? I experienced this in most ICU's of the hospitals to prevent the frequency of the signals to interfere with the frequencies of the medical machines.

By TASOS 0Score: 

5 years ago:  WHAT ABOUTH IN PHONE STANDBY MODE?

By ranjith 0Score: 

5 years ago:  sir,
i am a student of electonics and communication engineering 3 year.i took cellphone detector as my mini project.will this circuit work???
what is the value of the inductance we should use,would u suggest anyother circuit instead?pls send details to .(JavaScript must be enabled to view this email address)

By venkat 0Score: 

5 years ago:  i am very interest to service a cell phone without any bodys help i dont noany thing about electronics is anyway how to rectify a prolem tell me

By yna 0Score: 

5 years ago:  sir i am a student from the philippines and i want to conduct a project regarding cellphone detectors. are there any cheaper alternatives for the materials used?or can i make an improvised version? what can you suggest do i substitute and to which?

By Lu 0Score: 

5 years ago:  Sir, I would like to buy urgently the cell phone detector. Can you tell me how can I do, please?
Thank you! Best regards.

My email is lucrixx at yahoo.it

By Satellite Phones 0Score: 

5 years ago:  Cool Post! Very informative dude. I saw this site while browsing and think it may be relevant http://www.ustronics.com . Keep up the good work!

By channabasappa 0Score: 

5 years ago:  sir,
i am channabasappa studing in nttf 3rd sem. please tell me the working of the mobile detector circuitwith circuit diagram.

By kiruthiga 0Score: 

5 years ago:  can it be done breadbroad

By ali peek 0Score: 

5 years ago:  cool circuit! there may be some variations for this...

By Najmi 0Score: 

5 years ago:  Hi...
could you please tell me, how can i choose the most suitable material that can be used for design or fabrication a mobile-phone part by part, and why did we choose them and the their expected failure.
this is my email
.(JavaScript must be enabled to view this email address)
thanks so much

By chandras 0Score: 

5 years ago:  what is the range of the circuit that it can cover.

By Alfred 0Score: 

5 years ago:  Hi
I am electrical engineering student doing design I have taken a cell dector as my project and It is working but I want to put and 16by2 lcd display but i cannot interface a microcrontrller with the lcd display.Please can please give me ideas or websites I can get this information.

By Alfred 0Score: 

5 years ago:  Hi
I am electrical engineering student doing design I have taken a cell dector as my project and It is working but I want to put and 16by2 lcd display but i cannot interface a microcrontrller with the lcd display.Please can please give me ideas or websites I can get this information. my email is .(JavaScript must be enabled to view this email address)

By shikha 0Score: 

4 years ago:  Hi,
I am a student doing project. Please give me a valid mobile detection circuit to detect the mobiles in the standby mode.

By sreerag 0Score: 

4 years ago:  are there any equivalents for bat 43

By priya 0Score: 

4 years ago:  sir,
can any one tell me how can i interface dtmf chip to telephone system via microcontroller. please help me

By DHINESH 0Score: 

4 years ago:  I NEED RESENTLE MOBLE CIRCUITS SEND MY e-mail id -> parthirockz

By jahangir 0Score: 

4 years ago:  please give me the circuit diadram.

By poop 0Score: 

4 years ago:  wassup dawgs

By Josh 0Score: 

4 years ago:  Great project. I'm interested in modifying this detector so that GSM (900 - 1800MHz) triggers one LED to illuminate, and WiFi/Bluetooth (2400MHz) causes another to illuminate. Is this possible? Would it require 2 antenna?

Could you come up with any solutions? Thanks

By Dhamoder 0Score: 

4 years ago:  Sir,give me the solution to increase the radius of this devic plz give replay

By MAJID PASHA 0Score: 

4 years ago:  PLIES TEL ME THAT IT CAN WORKES WHAN PHONE IS ON STAND BY

By MOSHIUR RAHMAN 0Score: 

4 years ago:  THANKS FOR THE CIRCUIT DIAGRAM. IT WORKS!
EEE., AIUB.

By sangee 0Score: 

4 years ago:  what is the advantage of germanium diode or schotty diode than silisium diode?

By shienell 0Score: 

4 years ago:  please help me sir,

how it be possible to implement the cellphone detector has decade counter that will count the numbers of cellphone or how many cellphone is detect.
they will be has a output in seven segment.

please reply...

By Saurabh 0Score: 

4 years ago:  Sir I wanted to know whats the estimated cost of this.

By Fusera 0Score: 

4 years ago:  Very primitive, but useful circuit. :)

By Jaimee 0Score: 

4 years ago:  i need to know if kids can do something to their phone that wont set of the detector when they are using it. i wanna make my kids cant do that

By rajendra 0Score: 

4 years ago:  would u like to tell me about how can we increase range of it

By kanasai 0Score: 

4 years ago:  if I want to use it to detect the GSM signal 1900 Mhz, I can just use the formula to calculate the antenna lenght, which its lenght would be shorter, right?

By UB 0Score: 

4 years ago:  You should answer some of these questions sometime

By Amod 0Score: 

4 years ago:  Using cell detector tool, can we identify the mobile IMEI number

By pratheesh 0Score: 

4 years ago:  sir,
how we convert the variable voltage when call detected,in to a high voltage for driving microcontroller

By George 0Score: 

4 years ago:  Does it mean that nobody can help in designing circuit to detect cell phone on standby mode?

By anil 0Score: 

3 years ago:  dear sir,can i add some additional ckt to detect CDMA signal?

By vengatesh 0Score: 

3 years ago:  sir, in my area bat43 Schottky diode not available. give another alternative component for this diode

By za Khan 0Score: 

3 years ago:  sir i need a way to find out my living partner have a hidden mobile how can i found that in my presence every thing is quiet i wat to find that

By ductue 0Score: 

3 years ago:  Dear sir, why have two antennas perpendicular to each other?

By shahid 0Score: 

3 years ago:  i want GSM anti jammer circuit diagram with car engine kill.

By V.RAVI KIRAN 0Score: 

3 years ago:  1.could you please tell me what will be the cost of the cellphone detector project to do......
2.can i add some additional circuit detector to detect CDMA signal...
3.why have two perpencdicular to each other
...
4.how can take results from this circuit and can we hear that particular detected signal by this circuit at the same

5.give me circuit diagram

By hublyt 0Score: 

3 years ago:  So how does this give its output signal? The led lights up, or what? Or what is the stereo socket for, does it give a alarm signal from there?

By Raquif 0Score: 

3 years ago:  Hello sir, give me idea about cell ohone detector how they work in proper manner, and want know how they funtioned

By Md. Faisal Reza 0Score: 

3 years ago:  Sir,
cell phone detector can cover only 1meter .Please can u suggest me how i can increase the covering area.I will be thankful if u please give me the suggestion.

By santhosh 0Score: 

3 years ago:  sir.
i am student ,i wanna do project of phone detector so please can you tell me instruction and components for this i will be thankful if you give me suggestion

By gaurav 0Score: 

2 years ago:  hey guyzzzz plz suggest me the bst project, i m studing in poly final electronics .... plz suggest me 4-5 topics

Sampath Reddy
By Sampath Reddy (0) 0Score: 

2 years ago:  1.could you please tell me what will be the cost of the cellphone detector project to do......
2.can i add some additional circuit detector to detect CDMA signal...
3.why have two perpencdicular to each other
4.how can take results from this circuit and can we hear that particular detected signal by this circuit at the same
5.give me circuit diagram

kware Lambo
By kware Lambo (0) 0Score: 

1 year ago:  sir it wont works to me. why? do u have a full steps in making this project? kindly email it to me .(JavaScript must be enabled to view this email address) . bat45 diode is unavailable but the diode i used is also schotcky diode is it ok? my work doesnt light :( please help me thanks!! kinda neet it asap.

fadi Jabroun
By fadi Jabroun (0) 0Score: 

1 year ago:  Great.It works:D

Abhinandan Potdar

8 months ago:  Hi,
I tried tgis ckt, it works but within only 1 meter area.
can you plz mail me how to increase tha working area of this ckt.
thnQ

Jafis Pc
By Jafis Pc (0) 0Score: 

6 months ago:  I need know the range of the given circuit and is there any way to increase is it

Marc VIllalon
By Marc VIllalon (0) 0Score: 

6 months ago:  I would like to ask instead of using the stereo jack for the output can I replace it with LED?

Edward Jackson

1 week ago:  Great Project! Can the range of it be increased somehow? - Edward Jackson

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