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WelcomeWelcome

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A Presentation onA Presentation on

MOBILE BUGMOBILE BUG

Created By:Mr. Anuj Parihar

(Technokrity.com)

Prepared By:Neha Therkar

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CONTENTSCONTENTS

INTRODUCTION CIRCUIT DIAGRAM WORKING PIN CONFIGURATION OF IC APPLICATIONS LIMITATION

SUMMARY REFERENCES

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CIRCUIT DIAGRAMCIRCUIT DIAGRAM

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How the circuit works?How the circuit works?

Ordinary LC (Coil-Capacitor) circuits areOrdinary LC (Coil-Capacitor) circuits are

used to detect low frequency radiation inused 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 a

variable capacitor retrieve the signal from thevariable capacitor retrieve the signal from the

carrier wave.carrier wave.

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How the circuit works?How the circuit works?

But such LC circuits cannot detectBut such LC circuits cannot detect

high frequency waves near thehigh frequency waves near the

microwave region.microwave region.

Hence in the circuit, a capacitor isHence in the circuit, a capacitor is

used to detect RF from mobile phoneused to detect RF from mobile phone

considering that, a capacitor canconsidering that, a capacitor canstore energy even from an outsidestore energy even from an outside

source and oscillate like LC circuit.source and oscillate like LC circuit.

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Use of capacitorUse of capacitor

A capacitor has two electrodes separated by aA 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 passThe 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 selectedduring 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.

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Use of capacitorUse of capacitor

To detect the signal, the sensor partTo detect the signal, the sensor part

should be like an aerial. So theshould be like an aerial. So the

capacitor is arranged as a mini loopcapacitor is arranged as a mini loop

aerial (similar to the dipole antennaaerial (similar to the dipole antennaused in TV). In short with thisused in TV). In short with this

arrangement, the capacitor worksarrangement, the capacitor works

like an air core coil with ability tolike an air core coil with ability tooscillate and discharge current.oscillate and discharge current.

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

One lead of the capacitor gets DCOne lead of the capacitor gets DCfrom the positive rail and the otherfrom the positive rail and the otherlead goes to the negative input oflead goes to the negative input of

IC1. So the capacitor gets energy forIC1. So the capacitor gets energy forstorage. This energy is applied to thestorage. This energy is applied to theinputs of IC1 so that the inputs of ICinputs of IC1 so that the inputs of ICare almost balanced with 1.4 volts.are almost balanced with 1.4 volts.In this state output is zero. But atIn this state output is zero. But atany time IC can give a high output ifany time IC can give a high output ifa small current is induced to itsa small current is induced to itsinputsinputs..

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

There a natural electromagnetic fieldThere a natural electromagnetic fieldaround the capacitor caused by the 50Hzaround the capacitor caused by the 50Hzfrom electrical wiring. When the mobilefrom electrical wiring. When the mobilephone radiates high energy pulsations,phone radiates high energy pulsations,

capacitor oscillates and release energy incapacitor oscillates and release energy inthe inputs of IC. This oscillation isthe inputs of IC. This oscillation isindicated by the flashing of the LED andindicated by the flashing of the LED andbeeping of Buzzer. In short, capacitorbeeping of Buzzer. In short, capacitorcarries energy and is in ancarries energy and is in an

electromagnetic field. So a slight changeelectromagnetic field. So a slight changein field caused by the RF from phone willin field caused by the RF from phone willdisturb the field and forces the capacitordisturb the field and forces the capacitorto release energy.to release energy.

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PIN CONFIGURATION OF ICPIN CONFIGURATION OF IC

(1) ICCA 3130(1) ICCA 3130

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

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APPLICATIONAPPLICATION

It can be used to prevent use ofIt 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 useIt is also useful for detecting the use

of mobile phone for spying andof mobile phone for spying and

unauthorised video transmission.unauthorised video transmission.

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LIMITATIONLIMITATION

RANGE OF THE CIRCUITRANGE OF THE CIRCUIT

The prototype has only limited rangeThe prototype has only limited rangeof 2 metres.But if a preamplifierof 2 metres.But if a preamplifier

stage using JFET or MOSFETstage using JFET or MOSFET

transistor is used as an interfacetransistor is used as an interface

between the capacitor and IC,rangebetween the capacitor and IC,range

can be increased.can be increased.

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REFERENCEREFERENCE

www.google.comwww.google.com

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

www.efymag.comwww.efymag.com

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Thank YouThank You

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AnyAny

Queries???Queries???