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A Presentation on A Presentation on MOBILE BUGMOBILE BUG

Guided By:Prof. Amit Sharma

(H.O.D EC Dept.)Mrs. Ila VaghelaMs. Ekta Mehta

Prepared By:Meet Parekh(07 EC 054)Hiren Raval(07 EC 056)Pratik Vitthalpara(07 EC 060)

CONTENTSCONTENTS

INTRODUCTION CIRCUIT DIAGRAM WORKING PIN CONFIGURATION OF IC APPLICATIONS LIMITATION SUMMARY REFERENCES

CIRCUIT DIAGRAMCIRCUIT DIAGRAM

How the circuit works?How the circuit works?

Ordinary LC (Coil-Capacitor) circuits areOrdinary LC (Coil-Capacitor) circuits areused to detect low frequency radiation in used to detect low frequency radiation in the AM and FM bands.the AM and FM bands. The tuned tank circuit having a coil and aThe tuned tank circuit having a coil and avariable capacitor retrieve the signal from thevariable capacitor retrieve the signal from thecarrier wave.carrier wave.

How the circuit works?How the circuit works? But such LC circuits cannot detect But such LC circuits cannot detect high frequency waves near the high frequency waves near the microwave region. microwave region.

Hence in the circuit, a capacitor is Hence in the circuit, a capacitor is used to detect RF from mobile phoneused to detect RF from mobile phoneconsidering that, a capacitor can considering that, a capacitor can store energy even from an outside store energy even from an outside source and oscillate like LC circuit.source and oscillate like LC circuit.

Use of capacitorUse of capacitor A capacitor has two electrodes separated by a A capacitor has two electrodes separated by a ‘ ‘dielectric’ like paper, mica etc.dielectric’ like paper, mica etc.

The non polarized disc capacitor is used to pass The non polarized disc capacitor is used to pass AC and not DC.AC and not DC.

Capacitor can store energy and pass AC signalsCapacitor can store energy and pass AC signals during discharge. 0.22 capacitor is selected during discharge. 0.22 capacitor is selected because it is a low value one and has largebecause it is a low value one and has large surface area to accept energy from the mobilesurface area to accept energy from the mobile radiation. radiation.

Use of capacitorUse of capacitor

To detect the signal, the sensor part To detect the signal, the sensor part should be like an aerial. So the should be like an aerial. So the capacitor is arranged as a mini loop capacitor is arranged as a mini loop aerial (similar to the dipole antenna aerial (similar to the dipole antenna used in TV). In short with this used in TV). In short with this arrangement, the capacitor works arrangement, the capacitor works like an air core coil with ability to like an air core coil with ability to oscillate and discharge current.oscillate and discharge current.

How the capacitor senses RF?How the capacitor senses RF?

One lead of the capacitor gets DC One lead of the capacitor gets DC from the positive rail and the other from the positive rail and the other lead goes to the negative input of lead goes to the negative input of IC1. So the capacitor gets energy for IC1. So the capacitor gets energy for storage. This energy is applied to the storage. This energy is applied to the inputs of IC1 so that the inputs of IC inputs of IC1 so that the inputs of IC are almost balanced with 1.4 volts. In are almost balanced with 1.4 volts. In this state output is zero. But at any this state output is zero. But at any time IC can give a high output if a time IC can give a high output if a small current is induced to its inputssmall current is induced to its inputs. .

How the capacitor senses RF?How the capacitor senses RF? There a natural electromagnetic field There a natural electromagnetic field

around the capacitor caused by the 50Hz around the capacitor caused by the 50Hz from electrical wiring. When the mobile from electrical wiring. When the mobile phone radiates high energy pulsations, phone radiates high energy pulsations, capacitor oscillates and release energy in capacitor oscillates and release energy in the inputs of IC. This oscillation is the inputs of IC. This oscillation is indicated by the flashing of the LED and indicated by the flashing of the LED and beeping of Buzzer. In short, capacitor beeping of Buzzer. In short, capacitor carries energy and is in an carries energy and is in an electromagnetic field. So a slight change electromagnetic field. So a slight change in field caused by the RF from phone will in field caused by the RF from phone will disturb the field and forces the capacitor disturb the field and forces the capacitor to release energy.to release energy.

PIN CONFIGURATION OF IC PIN CONFIGURATION OF IC (1) ICCA 3130(1) ICCA 3130

(2) IC NE 555 TIMER(2) IC NE 555 TIMER

APPLICATIONAPPLICATION

It can be used to prevent use of It can be used to prevent use of mobile phones in examination halls , mobile phones in examination halls , confidential rooms , etc.confidential rooms , etc.

It is also useful for detecting the use It is also useful for detecting the use

of mobile phone for spying and of mobile phone for spying and unauthorised video transmission.unauthorised video transmission.

LIMITATIONLIMITATION

RANGE OF THE CIRCUITRANGE OF THE CIRCUIT

The prototype has only limited range The prototype has only limited range of 2 metres.But if a preamplifier of 2 metres.But if a preamplifier stage using JFET or MOSFET stage using JFET or MOSFET transistor is used as an interface transistor is used as an interface between the capacitor and IC,range between the capacitor and IC,range can be increased.can be increased.

REFERENCEREFERENCE

www.google.comwww.google.com www.wikipedia.orgwww.wikipedia.org www.pdfmachine.comwww.pdfmachine.com www.efymag.com www.efymag.com

Thank YouThank You

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