This project is a simple cell phone detector project. This
handy cell phone detector, pocket size mobile transmission sniffer can sense
the presence of an active cell phone in a radius of 1m-1.5m.
As the cell phone sends or receives a message or call, it
sends off a signal. This signal is detected by the circuit and will cause the
LED to blink and buzzer to sound. This is the basic principle of the project.
The circuit can detect incoming and outgoing calls, SMS,
MMS, GPRS usage and video transmission even when the mobile phone is set aside
in silent mode.
CIRCUIT DIAGRAM
¢The transmission frequency of a mobile
ranges from 0.9GHz to 3GHz.So a circuit capable of detecting gigahertz signals
is needed.
¢So 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.
- Capacitor C5 (47pF) is connected across ‘strobe’ (pin 8) and ‘null’ inputs (pin 1) of IC1 for phase compensation and gain control to optimize the frequency response.
- As the capacitor C4 receives the signal, the output of IC1 becomes high and low alternately depending on the frequency of the signal. This triggers the timer IC2 through capacitor C6 and the LED starts blinking and the piezoelectric buzzer starts sounding due to the timing components R5(10k) and C7(47uF) which set the ON time to 1 second.
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 meeting.
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 fatal consequences
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