DEPARTMENT OF INSTRUMENTATION

FACULTY OF TECHNOLOGY
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY
COCHIN - 682 022

CELL PHONE DETECTOR

PROJECT REPORT SUBMITTED BY

MARIYA JOHNY - 90017013

MOHAMMED FARIS K - 90017014
RAHUL G - 90017021
RAHULDAS H - 90017022

B.Tech. Instrumentation Technology

June 2020

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 DEPARTMENT OF INSTRUMENTATION
FACULTY OF TECHNOLOGY
COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY

COCHIN - 682 022

CELL PHONE DETECTOR

Guided by
Mrs. Nimmy John T, Assistant Professor, DOI, CUSAT

PROJECT REPORT SUBMITTED BY

MARIYA JOHNY - 90017013

MOHAMMED FARIS K - 90017014
RAHUL G - 90017021
RAHULDAS H - 90017022

B.Tech. Instrumentation Technology

June 2020

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 ABSTRACT

The most common electronic equipment used now-a-days is Cell Phone or

Mobile Phone. With advancement in communication technology, the
requirement of cell phones has increased dramatically. A cell phone typically
transmits and receives signals in the frequency range of 0.9 to 3GHz, which can
be detected using a designed circuit.This handy, pocket-size mobile transmission
detector can sense the presence of an activated mobile cell phone from one
meter. 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, and video transmission even if the mobile phone is kept in
the silent mode. Here we are constructing a simple and commercial cell phone
detector circuit using resistors, capacitors, transistor, op amp, LED, antenna,
bread board etc. The moment the device detects RF transmission signal from an
activated mobile phone, the LED blinks. The alarm continues until the signal
transmission ceases. Assemble the circuit on a general-purpose PCB as compact
as possible and enclose in a small box like junk mobile case.

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 TABLE OF CONTENTS

CHAPTER TITLE PAGE NO

NO
INTRODUCTION 01
1 1.1 OBJECTIVE 01
1.2 SCOPE OF THE WORK 01
HARDWARE DESCRIPTION 02
2 2.1 CIRCUIT DIAGRAM 02
2.2 COMPONENTS REQUIRED 03
2.2.1 CA 3130 OP-AMP 03
2.2.2 BC 548 NPN TRANSISTOR 05

HARDWARE IMPLEMENTATON 06
3 3.1 BASIC CONCEPT AND WORKING
OF CELL PHONE DETECTOR 06
4 RESULTS 08
CONCLUSION 09
5 5.1 CONCLUSION 09
5.2 FUTURE SCOPE 09
REFERENCES 10

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 CHAPTER 1

INTRODUCTION

1.1 OBJECTIVE

To create a cell phone detector that detects the presence of an activated

mobile phone.

1.2 SCOPE OF THE WORK

A mobile phone is a device that can make and receive telephone call over
a radio link while moving around a wide geographic area. It does so by
connecting to a cellular network provided by a mobile operator allowing access
to the public telephone network. By contrast a cordless telephone is used only
within the short range of a single private base station. In addition to telephony
modem mobile phones also support a wide variety of other services such as text
messaging, MMS, E-mail, Internet access, Bluetooth, gaming, and photography.
As increase in the technology in the world using the electronic equipment are
being used in a wrong way like, in the examination halls and confidential rooms.
To avoid this, we are introducing a project called CELLPHONE DETECTOR.
This handy, pocket-size mobile transmission detector or sniffer can sense the
presence of an activated mobile cell phone from one meter. 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.

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 CHAPTER 2

HARDWARE DESCRIPTION

2.1 CIRCUIT DIAGRAM

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2.2 COMPONENTS REQUIRED

 CA 3130 Op-Amp

 Resistors - 2.2 MΩ x 2, 100KΩ x 1, 1KΩ x 1

 Capacitors - 22pF x 2, 0.22nF, 47pF, 100uF

 BC 548 NPN Transistor

 LED

 Antenna

 Connecting wires

 9V battery

 PCB/Breadboard

2.2.1 CA 3130 OP-AMP

The CA3130 is a BiMOS Operational Amplifier with MOSFET. Bipolar op-

amps perform well under high bandwidths (fast switching) and CMOS op- amps
perform well by consuming less current. So, the CA3130 being a BiMOS op-
amp has the advantage of high bandwidth operation and less current

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consumption. The op-amp is built using MOSFETS and hence it has high input
impedance.
Like all voltage Comparators the CA3130 also has an Inverting Pin and a Non-
Inverting Pin. If the voltage at the Non-Inverting Terminal (pin 3) is high than
the Inverting Terminal (pin 2) the output (pin 7) will also be high else the output
will be low.
The CA3130 can work in a Single supply voltage or in a dual supply mode. For
now, let’s concentrate on the +5V supply voltage circuit since this is the most
used design for digital circuits. In this type, the VCC+ (pin 8) is connected to
+5V supply voltage and the VCC (pin 4) is grounded to hold it at 0V potential.
A sample circuit is shown below

Applications

• Frequency Generator/Distorter
• Mobile jammers
• Voltage follower circuits
• DAC circuits
• Peak Signal/Noise detectors
• Oscillator circuits

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2.2.2 BC 548 NPN TRANSISTOR

BC548 is an NPN transistor so the collector and emitter will be left open
(Reverse biased) when the base pin is held at ground and will be closed
(Forward biased) when a signal is provided to base pin. BC548 has a gain value
of 110 to 800, this value determines the amplification capacity of the transistor.
The maximum amount of current that could flow through the Collector pin is
500mA, hence we cannot connect loads that consume more than 500mA using
this transistor. To bias a transistor, we must supply current to base pin, this
current (IB) should be limited to 5mA.
When this transistor is fully biased, it can allow a maximum of 500mA to flow
across the collector and emitter. This stage is called Saturation Region and the
typical voltage allowed across the Collector-Emitter (VCE) or Base-Emitter (VBE)
could be 200 and 900 mV, respectively. When base current is removed the
transistor becomes fully off, this stage is called as the Cut-off Region and the
Base Emitter voltage could be around 660 mV.

Applications

• Driver Modules like Relay Driver, LED driver etc.

• Amplifier modules like Audio amplifiers, signal Amplifier etc.
• Darlington pair

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 CHAPTER 3

HARDWARE IMPLEMENTATION

3.1 BASIC CONCEPT AND WORKING OF CELL PHONE DETECTOR

PURPOSE OF THE CIRCUIT

This circuit is intended to detect unauthorized use of mobile phones in

examination halls, confidential rooms etc. It helps to detect unauthorized video
and audio recordings. It detects the signal from mobile phones even if it is kept
in the silent mode.

PRINCIPLE

Cell Phone Detector is a circuit that can sense the presence of any activated cell-
phone nearby and gives an indication of activated cell-phone near around of it.
Basically Cell-phone detector is a Frequency Detector or a Current to Voltage
Converter Circuit which catches frequencies about 0.8 - 3.0GHz (Mobile band
frequencies). RL tuned circuit (Resistor–Inductor circuit) is not suitable for
detecting the RF signals in Gigahertz range.
This Mobile Detector Circuit can detect incoming/outgoing calls, messaging,
video transmission and any SMS or GPRS uses within the range of 1 meter. This
circuit is extremely useful to detect Cell-phones at Cell-phone restricted places
like Exam halls, meeting rooms, hospitals etc. It is also useful in detecting the
unauthorised use or spying using hidden Cell Phone. It can detect the RF
Transmission from the Mobile Phone and LED blinks, even if the phone is kept
on Silent mode and this alarm continues beeping till the presence of RF signals .

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WORKING

The first half of the circuit makes RF signal detecting section. Capacitor C7(0.22
µF) is the main component which will sense high frequency RF signals. CA
3130 op amp is wired as an inverting amplifier with high gain. It provides
remarkably high input impedance and high-speed performance to amplify RF
signals detected by the capacitor C7. You can see that one terminal of the
capacitor C7 is biased with two resistors R6 and R7. Capacitor C6(100 µF) will
prevent any fluctuations in the bias voltage. Capacitor C9 and C8(22 pF) are
used to filter input signals. Thus, in normal conditions the op amp will be in
balanced state.
So, when high frequency mobile signals are present in the vicinity of this circuit,
the capacitor C7 will get energized and distorts the balance of the op amp. This
operates the T1(BC 548) transistor wired as a switch. Thus, the LED is operated
indicating the presence of cell phone

APPLICATION

 Can be used to find out whether there are any cellphones in a cellphone
restricted area.
 Can check whether cellphone can receive or send signals and is working
properly.
 It can be used for detecting mobile phones used for spying and
unauthorized transmission of audio and video.
 It is useful where the use of mobile phone is prohibited like petrol pumps
and gas stations, historical places, religious places, and court of laws.
 It can be used to detect stolen mobile phones.

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 CHAPTER 4

RESULTS

A mobile phone detector circuit is made successfully which can detect signals of
mobile phone which is 1 meter away. It indicates when presence of signal which
is emitted during an incoming or outgoing calls or messages or data connection
made is detected. The moment the bug detects RF transmission signal from an
activated mobile phone, the LED blinks. The blinking continues until the signal
transmission ceases.

CIRCUIT WHEN DETECTING CELL PHONE

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 CHAPTER 5

CONCLUSION

5.1 CONCLUSION

In this project we tried to design a mobile detector which can detect both the incoming and
the outgoing calls as well as the video transmission even if the mobile is kept at the silent
mode. It gives an indication of the activated mobile source by glowing its LED. The LED will
glow until the signal is ceases.

5.2 FUTURE SCOPE

Trying to increase the detecting range of cell phone detector to few more meters for observing
wide range of area.

In future we could be able to detect any range of frequencies over a meter of range and this
will be extremely useful to detect the cell phones where they are prohibited.

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 REFERENCES

➢ www.electronicsforu.com
➢ www.electronicshub.org
➢ www.electroschematics.com
➢ www.instructables.com

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