This document presents a mobile detector circuit that can detect incoming calls, texts, and video transmissions even when a mobile phone is set to silent mode. It consists of an antenna capacitor to capture RF signals, a voltage converter to convert the signals to voltages, a transistor amplifier, a timer circuit using an IC 555 chip to generate pulses, and a piezo buzzer to sound when a signal is detected. The circuit allows for detection of unauthorized mobile phone use in places like exam halls or confidential rooms, and can pick up signals from phones in silent mode. It has advantages of being low cost, easy to construct, and simple.

1. Welcome

2. A Presentation on
MOBILE DETECTOR
P.Monika
DePartMent of electronics,
seethalakshMi raM swaMi
college,trichy -2,
inDia.

3. INTRODUCTION




The circuit as a current to voltage converter with
capacitor connected between inverting and noninverting inputs.
The incoming and outgoing calls,sms and video
transmission detect the mobile phone is kept in the
silent mode.
An ordinary RF detector using tuned LC circuits.
Disk capacitor to capture the RF signals from the
mobile phone.

4. Block DiagraM
INPUT
INPUT
VOLTAGE
VOLTAGE
CONVERTOR
CONVERTOR
TRANSIS
TRANSIS
TOR
TOR
TIMER
TIMER
PIEZO
PIEZO
BUZZER
BUZZER

5. BLOCK DESCRIPTION
Voltage convertor:
The mobile is in silent mode if any calls and msg
comes the antenna received the signals and send the signal to
voltage convertor. The input and the output is the given to
transistor.
Transistor:
The output of voltage converter is the input of
transistor. The transistor amplified the signal and gives the
output to 555 timer form the pin2.

6. Timer :
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 pulse width
modulation is the input of 555 timer. The stable
pulse is the output of IC 555 timer.
Piezo buzzer:
Piezoelectricity is the ability of some material to
generate an electric field or electric potential in response to
applied mechanical stress. The output of the signal is given to
piezo buzzer and the sound is on.

7. CIRCUIT DIAGRAM

8. CIRCUIT DESCRIPTION

0.22µF Disk capacitor(C3) along with the leads acts as a small
antenna to collect the RF 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 IC
CA3130.

Resistor R3 acts as a feed back resistor.

C5 is connected for phase compensation.

9. 
Op-amp IC CA3130 converts the current to corresponding
voltage output.

Capacitor C4 and resistor R1 keeps the non-inverting input (3)
stable.

Resistor R2 provides the discharge path for capacitor C4.

Depending on the signal frequency detected by the C3,output
of the IC1becomes high and low alternatively, indicated by
LED1 and beeping of buzzer.

10. 
Mono-stable timer IC2 is triggered through capacitor C7.

Capacitor C6 maintains the base bias of transistor T1.

R6 and C9 reduce time delay.

11. APPLICATION
o
o
o
Mobile phone detect in Examination
halls, confidential rooms etc.
Detecting the use of mobile phone for
spying and unauthorized video
transmission
Detect the information receiving mobile
phone even if it is in silent mode.

12. ADVANTAGES




low cost
Easy to construct
Simple circuit
Suitable for Examination hall.

13. Thank You