A Mini Project Report on

CELLPHONE DETECTOR

Submitted to

BHARATI VIDYAPEETH COLLEGE OF ENGINEERING,NAVI MUMBAI

DEPARTMENT OF

ELECTRONICS AND COMMUNICATION ENGINEERING

By

PRADNYA KHANDGEAMIT NIMSE

AJINKYARAJ NAYAK

Under the Esteemed guidance of

Prof. Amina Qazi

Department of ET

BHARATI VIDYAPEETH COLLEGE OF ENGINEERING

Department of Electronics and Communication Engineering

CERTIFICATE

This is to certify that the mini project entitled “CELLPHONE DETECTOR” is submitted by

PRADNYA KHANDGE

AMIT NIMSE

AJINKYARAJ NAYAK

in partial fulfillment of the requirement for the Third Year of the degree Bachelor of Engineering

in Department of Electronics and Communication Engineering from Bharati Vidyapeeth College

Of Engineering, Navi Mumbai for the academic year 2014-2015.

Prof. Amina Qazi Prof. Kharade

Department, ET Head of the Department, ET

(Internal Guide)

Date: External Examiner

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Contents

1. Abstract 2

2. Basic Block Diagram and Description 3

3. Detailed Circuit Diagram and Working 5

4. Mathematical Analysis of the Circuit 7

5. Making of PCB Layout and Schematic 8

6. Project Implementation 10

7. Testing 11

8. Result 12

9. Appendix 13

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Abstract

This handy, pocket-size mobile transmission detector or sniffer can sense the

presence of an activated mobile cell phone from a distance of one and-a-half

meters. So it can be used to prevent use of mobile phones in examination halls,

confidential rooms, etc. It is also useful for detecting the use of mobile phone for

Spying and unauthorized video transmission. The circuit can detect the incoming

and outgoing calls, SMS and video transmission even if the mobile phone is kept in

the silent mode. The moment the Bug detects RF transmission signal from an

activated mobile phone, it starts sounding a beep alarm and the LED blinks. The

alarm continues until the Signal Transmission Ceases

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Basic Block Diagram

BLOCK DIAGRAM-

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MobilePhone

MobileTower

Buzzer

LED

Pulse GeneratorAmplifier

Antenna

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Description:

Mobile tower transmits the high frequency signal to the cell phone for

communication. The antenna captures the high frequency signal transmitted by mobile

tower to the mobile phone. The amplifier selects the proper frequency, which is often used for cell

phone communication and sends the signal to the pulse generator. The pulse generator generates the signal pulses in respect with

incoming signal. Pulses generated by pulse generator then given to the LED and Buzzer

for proper indication of Cell phone signals.

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Circuit Diagram

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Working:

Here the circuit uses a 0.22μF disk capacitor (C3) to capture the RF signals fromthe mobile phone. The lead length of the capacitor is fixed as 18 mm with aspacing of 8 mm between the leads to get the desired frequency. The disk capacitoralong with the leads acts as a small gigahertz loop antenna to collect the RF signalsfrom the mobile phone. Op-amp IC CA3130 (IC1) is used in the circuit as acurrent-to-voltage converter with capacitor C3 connected between its inverting andnon-inverting inputs. It is a CMOS version using gate-protected p-channelMOSFET transistors in the input to provide very high input impedance, very lowinput current and very high speed of performance.The output CMOS transistor is capable of swinging the output voltage to within 10mV of either supply voltage terminal. Capacitor C3 in conjunction with the leadinductance acts as a transmission line that intercepts the signals from the mobilephone. This capacitor creates a field, stores energy and transfers the stored energyin the form of minute current to the inputs of IC1.This will upset the balanced input of IC1 and convert the current into thecorresponding output voltage.Capacitor C4 along with high-value resistor R1 keeps the non-inverting inputstable for easy swing of the output to high state. Resistor R2 provides the dischargepath for capacitor C4. Feedback resistor R3 makes the inverting input high whenthe output becomes high. Capacitor C5 (47pF) is connected across ‘strobe’ (pin 8)and ‘null’ inputs (pin 1) of IC1 for phase compensation and gain control tooptimize the frequency response. When the mobile phone signal is detected by C3,the output of IC1 becomes high and low alternately according to the frequency ofthe signal as indicated by LED1. This triggers constable timer IC2 throughcapacitor C7. Capacitor C6 maintains the base bias of transistor T1 for fastswitching action. The low-value timing components R6 and C9 produce very shorttime delay to avoid audio nuisance.

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Mathematical Analysis

For the analysis of circuit only major parameters are considered. Which are

listed as follows.

Vcc = 9V

The voltages across transistor are:

VBE= 0.3V

VCE= 7.65V

VBC=8.7V

The input and output DC voltages of IC’s are:IC 3140 –

Input (pin 2) = 0.39V Output (pin6) =0.50V

IC NE555- Input (pin 2) = 9V Output (pin6) =9V

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PCB Layout and Schematic

Schematic and PCB layout are prepared by using Express PCB software.

Schematic:

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PCB Layout:

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Project Implementation

There are mainly three steps involved in project implementation Etching, Drilling and Soldering.

The detailed steps are given below:

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Etching:1) The mirror image of PCB layout is drown on the PCB with thick

marking of permanent marker.2) Prepared the Etching solution in the etching machine. Ferrous

chloride is used to prepare etching solution.3) Insert the PCB in the solution and set the timer of 15 minutes.4) Wash the PCB with cold water.5) Remove the marking of permanent marker using thiner.

Drilling:1) For Drilling the drill bit of 0.5 mm is used2) Drilling is completed with reference to PCB markings.

Soldering:1) Carefully solder components on PCB with proper lead spacing and lead

length.2) For mounting the IC the IC holder is used to avoid damage of IC during

soldering.

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Testing

The circuit is tested for the detection of cell phone signals. For signal receiving wired antenna is used. During testing, all the major measurements are taken such as voltages,

frequency etc. The circuit shows output over the range of 1-1.5 meter. Working is tested for outgoing as well as incoming calls on the cell phone.

And also foe the text massages. The range can be improved by improving the antenna parameters.

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ResultCell Phone Detector circuit detects the cell phone signals. And indicate themby blinking of LED and sound of the buzzer.It can detect the signals over the range of 1-1.5 meters.

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Appendix

CA3140 Datasheet:

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