SANJEET KUMAR JHA
o Design Objectives
o Frequency Range Detector
o Working Principle
o Basic block diagram
o Circuit Design
o Components Description-
Op-Amp IC1 CA3130
o Future Plan
Main scope of project is to sense the presence of an activated
mobile phone from a distance of one-and-a-half meters to prevent
the use in the examination halls, confidential rooms etc.
RF detector using tuned LC circuits is formed for detecting signals
in the GHz frequency.
Transmission frequency of mobile phone ranges from 0.9 to 3
As the cell phone sends or receives a message or call, it sends off
a signal. This signal is detected by our circuit and will cause the LED
to blink and buzzer to sound.
This simple circuit can detect any cell phone activities like
sending or receiving calls or SMS, or any type of data transmission.
The aim of the circuit is to receive the RF signal from mobiles &
detects its presence by alarming the sound.
The main objective includes building
a mobile detector to locate a phone
within one and a half radius and to
jam GSM signal within 5 to 10 meters
5 inch Antenna
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
The lead length of the capacitor is fixed as 18 mm with a
spacing of 8 mm between the leads to get the desired
The disk capacitor along with the leads acts as a small
gigahertz loop antenna to collect the RF signals from the
We use a disk capacitor C4(220nF), which will capture the
signals from the active cell phone transmission. The disk
capacitor along with its leads form a small gigahertz loop to
catch the signals.
The IC CA3130 is an op-amp, that is used in this circuit as a
current to voltage converter. The capacitor C4 leads are the
input for the IC1.
The IC1 provides the base voltage to the transistor Q1.
The circuit can detect the incoming and outgoing calls, SMS
and video transmission even if the mobile phone is kept in the
silent mode. The moment the Bug detects RF transmission
signal from an activated mobile phone, it starts sounding a
beep alarm and the LED blinks.
We are using a 5 inch antenna.
OP AMP IC1 CA3130
Op-amp IC CA3130 (IC1) is used in the circuit as a current-to voltage
NE555 TIMER IC
A555timer in mono-stablemodealongwith a high gainopamp isused to detect Giga
Hertz induced signals soproduced by an active cell phone with in closer proximityt o
sound a buzzeralarm.
It is a CMOS
version using gate-
transistors in the
input to provide
very high input
impedance, very low
input current and
very high speed of
15 kΩ, 12 kΩ, 1 k Ω, 100kΩ, 2.2 MΩ.
Total six resistors are there.
15 k Ω is connected with pin no 6
and 12 k Ω is connected with pin no
2 of the NE555 timer.
0.01 µF, 4.7 µF, 0.1 µF, 0.22 µF, 22 pF, 47 pF, 100
How does it work?
To detect the signal , the sensor part should be like an
The capacitor creates the fields, store the energy and
transfers this energy in the form of mini current to the
input of the IC1 which will upset the balanced input of IC1
and converts the current into output voltages..
1) It can be used to avoid the usage of mobile phones in
examination halls,seminar halls,quizzes etc.
2) It can be used to avoid video transmission in a secret or private
3) It can be used for military and civil defense purposes to detect
mobile phones by increasing its radius of range.
4) It can be used in hospitals and airplanes where,mobile
signals interfere with the electronic equipment which may have
• This cell phone detector circuit can sense the presence of
an activated mobile cell phone from a distance of one and-a-
• This cellular phone detector can detect any activity of a
mobile phone : incoming or outgoing SMS , video
transmission or voice transmission..
• This cellular phone detector electronic circuit diagram can
be used to verify the presence of an active cellular phone in
the tested area..
Over the allotted period we were able to
progress with our circuitry but it is far from
So in future we expect to complete the circuit
and implement a cellular detector through our