This document describes the design and components of a mobile detector circuit. It includes a block diagram showing the main components: a power supply, transformer, bridge rectifier, op-amp voltage converter, 555 timer circuit, transistor, and piezo buzzer. The detector works by using an antenna to pick up radio frequency signals from an activated mobile phone, which triggers the 555 timer circuit to activate the buzzer, alerting others to the phone's use. The detector has applications in places where mobile phone use needs to be restricted like exam halls, hospitals, and government facilities.

1. BY
R.SURESH (16705A0426)
B TECH II Year I Sem
ELECTRONICS & COMMUNICATION ENGINEERING
ANNAMACHARYA INSTITUTE OF TECHNOLOGYAND SCIENCES
(AN AUTONOMOUS INSTITUTION)
(Approved by AICTE,NEW DELHI & Affiliated to J.N.T.U Anantapuramu)
New Boyanapalli, RAJAMPET-516 126 (A.P)
A
TECHNICAL SEMINAR
ON
MOBILE DETECTOR

2. CONTENTS
 INTRODUCTION
 BLOCK DIAGRAM
 POWER SUPPLYY
TRANSFORMER
BRIDGE RECTIFIER
CIRCUIT DIAGRAM
OP – AMPLIFIER
555 IC TIMER
PIZEO BUZZER
ADVANTAGES & DISADVANTAGES
APPLICATIONS
CONCLUSION

3. INTRODUCTION
The moment the bug detects RF transmission signal from an activated mobile
phone, it starts sounding a beep alarm and the LED blinks. The alarm continues
until the signal transmission ceases. An ordinary RF detector using tuned LC
circuits is not suitable for detecting signals in the GHz frequency band used in
mobile phones.

4. BLOCK DIAGRAM

5. POWER SUPPLY

6. TRANSFORMER
 A transformer is a device that transfers
electrical energy from one circuit to another
through inductively coupled conductors — the
transformer's coils or "windings".
 The transformer used here is a 230/(12V-
0-12V) step down transformer.

7. BRIDGE RECTIFIER

8. CIRCUIT DIAGRAM
There are five major parts in the case of cell phone detector:
Antenna
LC tuner circuit
Current to voltage converter
555 Timer circuit
Output stage

9. This IC is a 15 MHz Operational
amplifier with MOSFET inputs and
Bipolar output.
 Gate-protected P-Channel MOSFET
(PMOS) transistors are used in the
input circuit to provide very-high-input
impedance, very-low-input current,
and exceptional speed performance.
We can also use this CA3130 as
voltage to current converter.
OP - AMP

10. 555 IC TIMER
The NE555 IC is a highly stable controller
capable of producing accurate timing pulses.
 For satiable multi vibrator operation as an
oscillator, the free running frequency and the
duty cycle are both accurately controlled with
two external resistors and one capacitor.
 The NE555 Timer ic is also used for
Precision Timing, Pulse Generation, Time
Delay Generation and Sequential Timing.

11. TRANSISTOR
Transistor BC548 is a CMOS version using gate protected p-channel MOSFET
transistors in the input to provide very high input impedance, very low input
current and very high speed of performance.

12. PIZEO BUZZER
 A buzzer is a signaling device, usually electronic, typically used in
automobiles, household appliances such as microwave ovens, or game shows.
PIZEO EFFECT:
Every day use of this phenomenon is used in
load cells. Load cells are used on large weigh
scales for trucks and large bin scales where
materials need to be weighed. The signals from
the cells are calibrated to compensate for the
weight of the scale so that the scale can be
zeroed out. The cell signal, because it is very
small, is sent to an amplifier head where is can
be read by the operator in units of weight. The
head unit can be set to read in metric or imperial
weights.

13. ADVANTAGES & DISADVANTAGES
The illegal use of cell phones is a growing and dangerous problem in
institutions.
 Small in size.
Detection of hidden cell phones
Long range –some RF can locate cell phones up to one mile away
DISADVANTAGES:
Cannot detect phones that are off or in airplane mode if a phone is powered
off or not transmitting, it is invisible to the detector.
ADVANTAGES:

14. APPLICATIONS
 Petrol pumps
 Gas station
 Historical places
 Religious places
 Court of laws
 Examination halls
 Spying and unauthorized video transmission
 Military bases
 Hospitals
 Theatres
 Conferences
 Embassies

15. CONCLUSION
This pocket-size mobile transmission detector or sniffer 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 use of mobile
phones in examination halls, confidential rooms.

17. QUERIES ?