1

CHAPTER-1

INTRODUCTION

This handy cell phone detector, pocket-size mobile transmission detector can sense

the presence of an activated mobile cell phone from a short distance. 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.

It senses the radio frequency (RF) transmissions from nearby cellular or mobile

phones. If required, other sources of RF transmissions can also be detected including two-

way radios, and other wireless communication devices. When a transmission is detected, an

alarm sequence begins that may include any combination of visual LED glows. In addition

the unit can be used as a static or portable detector, and it can be used to generate remote

alarms, activate other equipment (including remote indication devices) and extend alarm

messages into other areas.

Cellular phone technology is rapidly changing. Features like Bluetooth, USB,

high resolution cameras, microphones, Internet, 802.11 wireless, and memory cards are

added every year. Also, the communication technology a cellular phone uses such as

CDMA, GSM, 3G, and 4G are rapidly changing. Hence there is more chance for leaking of

confidential matter. In order to avoid such leakage of information cell phone detectors are

used.

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1.1 Components Used In Cell Phone Detector:

ANTENNA

IC CA3130

NE555 TIMER

BC548 TRANSISTOR

LED

PIEZO BUZZER

12V SUPPLY

RESISTORS

CAPACITORS

1.2 Antenna:

The size and shape of the antenna and the way it's constructed determine the gain and

directivity of the antenna. The antenna transmits and receives electromagnetic signals. When

gain increases the amount of desired signal energy that can be captured Increase but the

amount of environmental noise and interferences that's captured increases by the same

amount.

Antenna receives the radio frequency signals (RF signals) from the mobile phone.

The radio frequency signals are grasped by the antenna. In the detection process we use a

wire type antenna. An antenna (or aerial) is an electrical device which converts electric

currents into radio waves, and vice versa. It is usually used with a radio transmitter or radio

receiver. In transmission, a radio transmitter applies an oscillating radio frequency electric

current to the antenna's terminals, and the antenna radiates the energy from the current as

electromagnetic waves (radio waves). In reception, an antenna intercepts some of the power

of an electromagnetic wave in order to produce a tiny voltage at its terminals that is applied

to a receiver to be amplified. An antenna can be used for both transmitting and receiving.

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1.3 CA3130:

CA3130A and CA3130 are op amps that combine the advantage of both CMOS and

bipolar transistors. Gate-protected P-Channel MOSFET (PMOS) transistors are used in the

input circuit to provide very-high-input impedance, very-low-input current and exceptional

speed performance. The use of PMOS transistors in the input stage results in common-mode

input-voltage capability down to 0.5V below the negative-supply terminal, an important

attribute in single-supply applications.

A CMOS transistor-pair, capable of swinging the output voltage to within 10mV of

either supply-voltage terminal (at very high values of load impedance), is employed as the

output circuit. The CA3130 Series circuits operate at supply voltages ranging from 5V to

16V, (±2.5V to ±8V). They can be phase compensated with a single external capacitor, and

have terminals for adjustment of offset voltage for applications requiring offset-null

capability. Terminal provisions are also made to permit strobing of the output stage. The

CA3130A offers superior input characteristics over those of the CA3130.

1.3.1 Features of CA3130:

• MOSFET Input Stage Provides:

- Very High ZI = 1.5 TΩ (1.5 x 1012Ω) (Typ)

- Very Low II . . . . . . . . . . . . . 5pA (Typ) at 15V Operation

. . . . . . . . . . . . . . . . . . . . . .= 2pA (Typ) at 5V Operation

• Ideal for Single-Supply Applications

• Common-Mode Input-Voltage Range Includes negative Supply Rail; Input Terminals can

be Swung 0.5V Below Negative Supply Rail

• CMOS Output Stage Permits Signal Swing to Either (or

both) Supply Rails

• Pb-Free Plus Anneal Available (RoHS Compliant)

1.3.2 Applications of CA3130:

• Ground-Referenced Single Supply Amplifiers

• Fast Sample-Hold Amplifiers

• Long-Duration Timers/Monostables

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• High-Input-Impedance Comparators

(Ideal Interface with Digital CMOS)

• High-Input-Impedance Wideband Amplifiers

• Voltage Followers (e.g. Follower for Single-Supply D/A

Converter)

• Voltage Regulators (Permits Control of Output Voltage

Down to 0V)

• Peak Detectors

• Single-Supply Full-Wave Precision Rectifiers

• Photo-Diode Sensor Amplifiers

Pin Diagram of CA3130:

Fig 1.1: Pin diagram of CA3130

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1.4 IC 555 Timers:

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, pulse

generation and oscillator applications. The part is still in widespread use, thanks to its ease of

use, low price and good stability. As of 2003, it was estimated that 1 billion units are

manufactured every year.

1.4.1 Design:

The IC design was proposed in 1970 by Hans R. Camenzind and Jim Ball. After

prototyping, the design was ported to the Monochip analogue array, incorporating detailed

design by Wayne Foletta and others from Qualidyne Semiconductors. Signetics (later

acquired by Philips) took over the design and production, and released the first 555s in 1971.

Depending on the manufacturer, the standard 555 package includes over 20 transistors,

2 diodes and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package

(DIP-8).Variants available include the 556 (a 14-pin DIP combining two 555s on one chip),

and the 558 (a 16-pin DIP combining four slightly modified 555s with DIS & THR

connected internally, and TR is falling edge sensitive instead of level sensitive).

The NE555 parts were commercial temperature range, 0 °C to +70 °C, and the SE555

part number designated the military temperature range, −55 °C to +125 °C. These were

available in both high-reliability metal can (T package) and inexpensive epoxy plastic (V

package) packages. Thus the full part numbers were NE555V, NE555T, SE555V, and

SE555T. It has been hypothesized that the 555 got its name from the three 5 kΩ resistors

used within, but Hans Camenzind has stated that the number was arbitrary.

Low-power versions of the 555 are also available, such as the 7555 and CMOS

TLC555.The 7555 is designed to cause less supply glitching than the classic 555 and the

manufacturer claims that it usually does not require a "control" capacitor and in many cases

does not require a decoupling capacitor on the power supply. Such a practice should

nevertheless be avoided, because noise produced by the timer or variation in power supply

voltage might interfere with other parts of a circuit or influence its threshold voltages.

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Fig 1.2: Pin diagram of IC 555

The connection of the pins for a DIP package is as follows:

Pin Name Purpose

1 GND Ground, low level (0 V)

2 TRIG OUT rises, and interval starts, when this input falls below 1/3 VCC.

3 OUT This output is driven to +VCC or GND.

4 RESET A timing interval may be interrupted by driving this input to GND.

5 CTRL "Control" access to the internal voltage divider (by default, 2/3 VCC).

6 THR The interval ends when the voltage at THR is greater than at CTRL.

7 DIS Open collector output; may discharge a capacitor between intervals.

8 V+, VCC Positive supply voltage is usually between 3 and 15 V.

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1.4.2 Modes:

The 555 has three operating modes:

Monostable mode: in this mode, the 555 functions as a "one-shot" pulse generator.

Applications include timers, missing pulse detection, bounce free switches, touch

switches, frequency divider, capacitance measurement, pulse-width modulation

(PWM) and so on.

Astable – free running mode: the 555 can operate as an oscillator. Uses include LED

and lamp flashers, pulse generation, logic clocks, tone generation, security alarms,

pulse position modulation and so on. Selecting a thermistor as timing resistor allows

the use of the 555 in a temperature sensor: the period of the output pulse is

determined by the temperature. The use of a microprocessor based circuit can then

convert the pulse period to temperature, linearize it and even provide calibration

means.

Bistable mode or Schmitt trigger: the 555 can operate as a flip-flop, if the DIS pin is

not connected and no capacitor is used. Uses include bounce free latched switches.

1.4.3 Monostable Operation:

Fig 1.3: Schematic of a 555 in monostable mode

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Fig 1.4: Monostable Characteristics

The relationships of the trigger signal, the voltage on C and the pulse width in

monostable mode

In the monostable mode, the 555 timer acts as a “one-shot” pulse generator. The

pulse begins when the 555 timer receives a signal at the trigger input that falls below a third

of the voltage supply. The width of the output pulse is determined by the time constant of an

RC network, which consists of a capacitor (C) and a resistor (R). The output pulse ends

when the voltage on the capacitor equals 2/3 of the supply voltage. The output pulse width

can be lengthened or shortened to the need of the specific application by adjusting the values

of R and C.

The output pulse width of time t, which is the time it takes to charge C to 2/3 of the supply

voltage, is given by

Where t is in seconds, R is in ohms and C is in farads. See RC circuit for an explanation of

this effect.While using the timer IC in monostable mode, the main disadvantage is that the

time span between the two triggering pulses must be greater than the RC time constant.

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1.4.4 Features of 555 Timer:

Turn-off time less than 2ms

Max. operating frequency greater than 500 kHz

Timing from microseconds to hours

Operates in both astable and monostable modes

Adjustable duty cycle

TTL compatible

Temperature stability of 0.005% per °C

1.4.5 Applications of 555 Timer:

Precision timing

Pulse generation

Sequential timing

Time delay generation

Pulse width modulation

1.5 BC548 Transistor:

The BC548 is a general purpose silicon NPN BJT transistor. The "BC" part of the

number designates a low power silicon NPN transistor. Transistor is a “CURRENT”

operated device which has a very large amount of current (Ic) which flows without restraint

through the device between the collector and emitter terminals. Transistors are circuit

elements designed to function either as amplifiers or as switches.

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Fig 1.5: BC548 Transistor

1.5.1 Applications of BC548 Transistor:

A common application for NPN transistors is to use then as switches in circuits.

Another application for NPN transistors is to use them as an voltage amplifier.

It can also be used as current amplifier.

1.6 LED:

LED means Light Emitting Diode. It is an electronic device that lights up when

electricity is passed through it. LEDs are usually red. They are good for displaying images

because they can be relatively small.The moment the bug detects RF transmission signal

from an activated mobile phone, it starts sounding a beep alarm and the LED blinks.LED‟s

contain an integrated multivibrator circuit inside which causes the LED to flash with a

typical time period.

A light-emitting diode (LED) is a semiconductor light source.LED‟s are used as

indicator lamps in many devices and are increasingly used for other lighting. When a light-

emitting diode is forward-biased (switched on), electrons are able to recombine with electron

holes within the device, releasing energy in the form of photons. This effect is called

electroluminescence and the colour of the light (corresponding to the energy of the photon)

is determined by the energy gap of the semiconductor. LEDs are often small in area (less

than 1 mm2), and integrated optical components may be used to shape its radiation pattern

LEDs present many advantages over incandescent light sources including lower energy

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consumption, longer lifetime, improved robustness, smaller size, and faster switching. LEDs

powerful enough for room lighting are relatively expensive and require more precise current

and heat management than compact fluorescent lamp sources of comparable output.

Fig 1.6: Light Emitting Diodes

1.7 Piezo Buzzer:

The piezo buzzer produces sound based on reverse of the piezoelectric effect. These

buzzers can be used alert a user of an event corresponding to a switching action, counter

signal or sensor input.The buzzer produces a same noisy sound irrespective of the voltage

variation applied to it. It consists of piezo crystals between two conductors.When a potential

is applied across these crystals, they push on one conductor and pull on the other.This, push

and pull action, results in a sound wave. Most buzzers produce sound in the range of 2 to 4

kHz.

Fig1.7: Piezo Buzzer

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A piezoelectric disk generates a voltage when deformed (change in shape is greatly

exaggerated). A piezoelectric sensor is a device that uses the piezoelectric effect to measure

pressure, acceleration, strain or force by converting them to an electrical charge.

Piezoelectric sensors have proven to be versatile tools for the measurement of various

processes. They are used for quality assurance, process control and for research and

development in many different industries.

Structure of Piezo Buzzer:

Fig 1.8: Structure of piezo buzzer

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CHAPTER-2

IMPLEMENTATION

Block Diagram:

Fig 2.1: Block Diagram

2.1 Algorithm:

STEP-1 : Supply is given to activate the circuit.

STEP-2 : A transaction is made through the mobile.

STEP-3 : The antenna receives the IR signals and passes them to op-amp.

STEP-4 : LED glows indicating that IR signals are sensed.

STEP-5 : The output of op-amp is fed to the timer.

STEP-6 : The timer is triggered.

STEP-7 : The timer activates the buzzer.

STEP-8 : The buzzer indicates that the cell phone is detected.

MOBILE

PHONE

RECEIVER

ANTENNA

CURRENT

TO

VOLTAGE

CONVERT

ER

TIMER SPEAKER

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Flow Chart:

Fig 2.2: Flow chart

START

SUPPLY IS GIVEN

TRANSACTION THROUGH

MOBILE

ANTENNA RECIEVES IR SIGNALS

SIGNALS ARE PASSED THROUGH

OP-AMP

LED GLOWS

OUTPUT OF OP-AMP IS FED

TO TIMER

TIMER IS TRIGGERED

BUZZER IS ACTIVATED

CELL PHONE

IS DETECTED

STOP

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Circuit Diagram:

Fig 2.3: Circuit Diagram

2.2 Operation of Cell Phone Detector:

An ordinary RF detector using tuned LC circuits is not suitable for detecting signals

in the GHz frequency band used in mobile phones. The transmission frequency of mobile

phones ranges from 0.9 to 3 GHz with a wavelength of 3.3 to 10 cm. So a circuit detecting

gigahertz signals is required for a mobile bug. Here the circuit uses a 0.22μF disk capacitor

(C3) to capture the RF signals from the mobile phone. The lead length of the capacitor is

fixed as 18 mm with a spacing of 8 mm between the leads to get the desired frequency. The

disk capacitor along with the leads acts as a small gigahertz loop antenna to collect the RF

signals from the mobile phone.

Op-amp IC CA3130 (IC1) is used in the circuit as a current-to-voltage converter with

capacitor C3 connected between its inverting and non-inverting inputs. It is a CMOS version

using gate-protected p-channel MOSFET transistors in the input to provide very high input

impedance, very low input current and very high speed of performance. The output CMOS

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transistor is capable of swinging the output voltage to within 10 mV of either supply voltage

terminal.

Capacitor C3 in conjunction with the lead inductance acts as a transmission line that

intercepts the signals from the mobile phone. This capacitor creates a field, stores energy and

transfers the stored energy in the form of minute current to the inputs of IC1. This will upset

the balanced input of IC1 and convert the current into the corresponding output voltage.

Capacitor C4 along with high-value resistor R1 keeps the non-inverting input stable

for easy swing of the output to high state. Resistor R2 provides the discharge path for

capacitor C4. Feedback resistor R3 makes the inverting input high when the 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 to optimize 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 of the signal as indicated by LED1. This triggers

monostable timer IC2 through capacitor C7. Capacitor C6 maintains the base bias of

transistor T1 for fast switching action. The low-value timing components R6 and C9 produce

very short time delay to avoid audio nuisance.

Assemble the circuit on a general purpose PCB as compact as possible and enclose in

a small box like junk mobile case. As mentioned earlier, capacitor C3 should have a lead

length of 18 mm with lead spacing of 8 mm. Carefully solder the capacitor in standing

position with equal spacing of the leads. The response can be optimized by trimming the

lead length of C3 for the desired frequency. You may use a short telescopic type antenna.

Use the miniature 12V battery of a remote control and a small buzzer to make the gadget

pocket-size. The unit will give the warning indication if someone uses mobile phone within a

radius of 1.5 meters.

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CHAPTER-3

APPLICATIONS OFCELL PHONE DETECTORS

3.1 Military Basis:

In government buildings and military bases the unit should be installed in all

sensitive areas. In addition to potential RAT phones, the Cellphone Detector can detect bugs

emitting RF within the specified band range. In addition, it can be rigged to trigger a digital

camera to capture an image of a person using a phone in a restricted area by sending a signal

to an external trigger mechanism from the remote alarm terminal.

3.2 Prisons:

Cellphone Detector may be placed outside cell doors during „lock up‟ hours within

prison wings to reduce illicit cellular phone activity. In addition, Cellphone Detector maybe

installed in entranceways, corridors, waiting and meeting areas where inmates‟ visits are

conducted.

3.3 Hospitals:

Cellphone Detector units are installed in general locations in corridors and waiting

rooms to deter nuisance public cellular phone usage. Sensitive electronic equipment within

intensive care wards and operating theatres that are vulnerable to RF interference will have

units installed near them.

3.4 Schools and Colleges:

Cellphone Detector units are installed in general locations in corridors, assembly

points, concourses, classrooms and lecture theatres to promote conformity and establishment

order. Cellphone detector units are deployed in examination rooms to deter examination

fraud via text messaging.

3.5 Places of Worship:

Cellphone Detector units are installed as a deterrent at the main entrance. Where

cellular phone misuse is a severe or persistent problem then units can be installed in the main

prayer area with audio alert set to low volume.

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3.6 Museums and Libraries:

Cellphone Detector units are installed in all areas in museums and libraries with

audio warning on low volume.

3.7 Courtrooms:

Cellphone Detector units are installed directly outside courtrooms with range set to

near. Inside the courtroom itself, a wall-mounted unit silently flashing in the public gallery

may alert security staff.

3.8 General Application:

Cellular phone detection and deterrence is an additional layer of security for your

organization. How effective this layer of security will be will be dependent on the

environment, the number of devices installed and how the detectors are integrated with other

layers of security such as metal detection and access control systems. Confidential advice

and assistance regarding how this product can be used is available from your supplier.

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CHAPTER-4

PROJECT KIT

4.1 Circuit Connections:

Fig 4.1: Circuit Connections

The connections of the circuit are made as per the circuit diagram which is shown in the

above figure.

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4.2 Results:

Fig 4.2: Results of cell phone detector

A transaction is made through a cell phone and it is brought near the circuit. Then the

IR signals are detected by the antenna and the LED glows and the buzzer rings indicating

that the cell phone is detected.

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CHAPTER-5

CONCLUSION

Cellular phone technology is gaining new data capabilities very rapidly. New

features like Bluetooth, high resolution cameras, memory cards, and Internet make them

ideal for getting data in and out of secure facilities. A cellular phone uses many different

transmission protocols such as FDMA or CDMA. These protocols dictate how a cellular

phone communicates with the tower. Typically cellular phones in the United States operate

between 824 - 894 MHz.

Many businesses depend on keeping information protected and build fortresses that

called secure facilities to protect their investment. Currently the only way to ensure that no

one is bringing a cellular phone into a secure facility is to search everyone entering and

exiting. This requires a lot of manpower and money to implement.

This project is used for military and civil defense for mobile radiation detection.

Used for spying the unauthorized video transmission in mobile phones. Used to prevent the

usage of mobile phones in examination and seminar halls. The signals emitted by mobile

phones can interfere with some electronic equipment inside the hospital. This could have

fatal consequences.so we use this project to detect the usage of mobile phones in the above

places.

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REFERENCES

www.alldatasheets.com

www.efyprojects.com

www.circuitstudy.com