Mobile Bug Power Point Presentation

MOBILE PHONE MOBILE PHONE DETECTORDETECTOR

PAVANKUMAR K K(1PI08EE126)SHASHI BHUSHAN A S (1PI08EE090)

ANTENNACURRENT TO

VOLTAGE CONVERTER

555 TIMER CIRCUIT

OUTPUT STAGE

BLOCK DIAGRAM

CIRCUIT DIAGRAMCIRCUIT DIAGRAM

How the circuit works?How the circuit works? THE ANTENNA RECEIVES THE SIGNAL AND THE ANTENNA RECEIVES THE SIGNAL AND

SENDS IT TO THE OP-AMP.SENDS IT TO THE OP-AMP. SINCE THIS IS THE CURRENT SIGNAL IT SINCE THIS IS THE CURRENT SIGNAL IT

NEEDS TO BE CONVERTED TO VOLTAGE NEEDS TO BE CONVERTED TO VOLTAGE SIGNAL .SIGNAL .

SO AN IC CA 3130 WHICH IS AN OPAMP IS SO AN IC CA 3130 WHICH IS AN OPAMP IS USED.USED.

THIS IC FEEDS THE TRANSISTOR WITH THE THIS IC FEEDS THE TRANSISTOR WITH THE VOLTAGE SIGNAL.VOLTAGE SIGNAL.

THIS AMPLIFIES THE SIGNAL AND THEN IT IS THIS AMPLIFIES THE SIGNAL AND THEN IT IS FED INTO THE 555 TIMER.FED INTO THE 555 TIMER.

THUS THE LED GOES HIGH AND THE BUZZER THUS THE LED GOES HIGH AND THE BUZZER BEEPS.BEEPS.

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 IC CA 3130IC CA 3130

IC LM 555 TIMERIC LM 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 1 metres.But if a preamplifier of 1 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.