We provide you Project Cell Phone Detector.You can choose the best of your choice and interest from the list of topics we suggested. All new project ideas that are appearing focuses to improve the knowledge of Engineering students. https://www.elprocus.com Visit our page to get more ideas on Project Report Format for Final Year Engineering Students these ideas developed by professionals. Elprocus provides free verified electronic projects kits around the world with abstracts, circuit diagrams, and free electronic software. We provide guidance manual for Do It Yourself Kits (DIY) with the modules at best price along with free shipping.

1. Cell Phone Detector

2. http://www.elprocus.com/
What is Cell Phone Detector?
 Nowadays, everyone is most familiar with Cell Phone Active
Detectors.
 The cell phone detectors are mostly handy and pocket-size mobile
transmission sensors.
 It can sense the presence of an activated mobile phone from a
distance of one and a half meters.
 So it can be used to prevent the use of mobile phones in examination
halls, confidential rooms, etc.

3. http://www.elprocus.com/
Uses of Cell Phone Detector
 It is also useful for detecting the use of mobile phone for spying
and unauthorized video transmission.
 To identify and restrict the use of mobile phones, this proposed
system is very helpful.
 It detects the incoming and outgoing calls, SMS, and video
transmission even if the mobile phone is kept in the silent mode.
 The illegal use of cell phones is a growing and dangerous problem
in correctional institutions worldwide.

4. http://www.elprocus.com/
Circuit Diagram

5. http://www.elprocus.com/
Cell Phone Detector Circuit Explanation
 The circuit uses a 0.22μF disk capacitor to capture the RF signals
from the mobile phone.
 This part should be like an aerial, so the capacitor is arranged as a
mini loop aerial. In short with this arrangement the capacitor works
like an air core with ability to oscillate and discharge current.
 The output of transistor is within 10 mV of either supply voltage
terminal.
 The lead inductance acts as a transmission line that intercepts the
signals from the mobile phone.

6. http://www.elprocus.com/
Frequency Range of Detector
 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 bug.
 The lead length of the capacitor is fixed as 18 mm with a spacing of 8
mm between the leads to get the desired frequency.
 The disk capacitor along with the leads acts as a small gigahertz
loop antenna to collect the RF signals from the mobile phone.
 When mobile phone is active, it transmits the signal in the form of
sine wave which passes through the space.

7. http://www.elprocus.com/
 The encoded audio/video signal contains electromagnetic radiation
which is picked up by the receiver in the base station.
 The transmitter power of the modern 2G antenna in the base station
is 20-100 watts.
 The mobile phone transmits short signals at regular intervals to
register its availability to the nearest base station.
 Distance to cellular base station is the most important environmental
factor. Generally, the nearer a cellular phone is to a base station or
transmitting tower, the weaker will be the signal that needs to come
from the phone.
Frequency Range of Detector

8. http://www.elprocus.com/
 Range of frequencies of different categories are, AM radio
frequencies between 180 kHz and 1.6MHz,FM radio uses 88 to 180
MHz, TV uses 470 to 854MHz.waves at higher frequencies but within
the RF region is called Micro waves.
 Mobile phone uses high frequency RF wave in the micro wave region
carrying huge amount of electromagnetic energy.
Frequency Range of Detector

9. http://www.elprocus.com/
Block diagram of cell phone detector

10. http://www.elprocus.com/
 One lead of the capacitor gets DC from the positive rail and the
other lead goes to the negative input of IC1. So the capacitor gets
energy for storage.
 This energy is applied to the inputs of IC1 so the inputs of IC1 are
almost balanced with 1.4 volts. In this state output is zero. But at
any time IC can give a high output if small current is induced to its
inputs.
 When mobile phone radiates, due to high energy pulsations,
capacitor oscillates and releases energy.
Working of Cell Phone Detector

11. http://www.elprocus.com/
Working of Cell Phone Detector
 When the mobile phone signal is detected then the output of U1
becomes high and low alternately according to the frequency of
the signal. This triggers mono-stable timer U2 through.
 And the TR pin of 555timer goes low then pin3 of timer becomes
high. When pin3 is high then buzzer will ring.
 You may use a short telescopic type antenna. The unit will give the
warning indication if someone uses mobile phone within a radius
of 1.5 meters.

12. http://www.elprocus.com/
Advantages of Cell Phone Detector
 Smaller in size
 Detection of hidden cell phones

13. http://www.elprocus.com/
Applications of Cell Phone Detector
It is useful where the use of mobile phone is prohibited like
 Petrol pumps
 Gas station
 Historical places
 Religious places
 Court of laws
 Examination halls
 Spying and unauthorized video transmission
 Military bases
 Hospitals
 Theatres
 Conferences
 Embassies

14. http://www.elprocus.com/
Conclusion
 Today cell phone detectors are widely used in many places to
detect the misuse of communication.
 The working capability of a cell phone detector is really wonderful
and can be operated very efficiently.
 Here Edgefx provides you a lot of information about electrical
instruments that are particularly useful for all Engineering
students.

15. http://www.elprocus.com/