CELL PHONE DETECTOR

PRESENED BY:

VISHNU VIJAYAN

MINI PROJECT

ABSTRACT Cell phone detector is a circuit that

sense the presence of any activated cell phone nearby and gives an indication of activated cell phone near around of it. It is a frequency detector which catches frequencies about 0.8-3GHz.This is very helpful to detect cell phones at cell phones restricted places like exam cells, meeting rooms, hospitals etc.

BLOCK DIAGRAM

Block diagram of cell phone detector

CIRCUIT DIAGRAM

Circuit diagram of cell phone detector

WORKING A LED and buzzer are used for indication of presence of cell phone.

Op-amp is configured as Frequency Detector or Current to Voltage Converter and its output is connected to a LED and buzzer using NPN and PNP transistors.

Two 100nF capacitors (C2 and C3), in parallel, are used for detecting RF signal from Mobile Phone. These capacitors are working as loop antenna for the system.

When there is any call or SMS then capacitors in parallel detect the data transmission frequencies or RF signal and output of op-amp goes high or low due to generated current at the input side of op-amp.

Due to these fluctuations, LED turns on and off through NPN transistor according to the signal’s frequency.

ADVANTAGES Smaller in size. Detection of hidden cell phones.

APPLICATIONSCell phone detector is useful where the

use of mobile phones is prohibited like:

Examination halls. Hospitals. Petrol pumps. Gas stations. Historical places etc.

THANK YOU