Cell Phone Detector ppt- IIEST, Shibpur

simple cell phone detector circuit

1. CELL PHONE DETECTOR Compiled and Presented by: Irene Lalhminghlui - 510615018 Subhajit Dutta -510615007 Priyadeep Biswas - 510615015 Ranapratap Majee - 510615001 Gaurab Bhowmik -510615009 Somdutta Tikadar - 510615012

2. OVERVIEW : WHAT IS A CELL PHONE DETECTOR? CIRCUIT DIAGRAM WORKING OF CIRCUIT COMPONENTS WORKING PRINCIPLE APPLICATIONS OF THE DEVICE CONCLUSIONS

3. WHAT IS A CELL PHONE DETECTOR? This handy cell phone detector can sense the presence of an activated cell phone from a distance of one and a-half meters. It can detect both the incoming and outgoing calls, SMS and video transmission even if the cell phone is kept in silent mode. The moment the bug detects RF transmission signal from an activated cell phone, the LED starts blinking, until signal transmission ceases.

4. CIRCUIT DIAGRAM:

5. WORKING OF CIRCUIT COMPONENTS LINE VEROBOARD : Line Vero is used in this circuit. CA3130 IC : CMOS version gate-protected p-channel MOSFET. Acts as an Differential Amplifier. Used in the circuit as a Current to Voltage converter. Provides very high input impedance , very low input current and very high speed of performance.

6. 1 k Ω RESISTOR: Colour code sequence Brown, Black, Yellow, Gold. Keeps the non-inverting input stable for easy swing of the output to high state. 100 K Ω RESISTOR: Colour code sequence Brown, Black, Yellow, Gold. Provides the discharge path for 0.22 µF Capacitor.

7. 0.22 µF CAPACITOR : Ceramic capacitor type. Acts as a small gigahertz (GHz) loop antenna to collect the RF signals from the mobile phone. The lead length of the is 18 mm with a spacing of 8 mm between the leads to get the desired frequency. 100 µF CAPACITOR : Electrolytic Capacitor.

8. BC548 TRANSISTOR : n-p-n type epitaxial silicon transistor. B indicates the material silicon and C stands for low audio frequency. Mainly use for switching and amplification purposes. 9 V BATTERY : Rectangular prism shape with round edges and a polarized snap connector at the top. This type is commonly used in walkie talkies, clocks and smoke detectors.

9. BATTERY CLIP : Necessary for holding the battery into place. Keep in mind the polarity, while using a battery clip. LED : Light Emitting Diode with two lead semiconductor light source. It is a p-n junction diode, which emits light when activated. We have also used connecting wires.

10. 2.2 M Ω RESISTOR : Colour code: Red, Red, Green and Gold. Makes the inverting input high when Output become high. 47 pF CAPACITOR : Ceramic Capacitor acts as the dielectric. Connected across strobe (pin 8) and null Input (pin 1) of the IC. For phase-composition and gain control to optimize the frequency response.

11. WORKING PRINCIPLE : Ordinary LC (Coil-Capacitor) circuits are used to detect low frequency radiation in the AM and FM bands . It can detect maximum MHz frequency. From Mobile phone we get frequency in terms of GHz.

12. WORKING PRINCIPLE : The transmission frequency of mobile phone ranges from 0.9 to 3 GHz with wave length of 3.3 to 10 cm. So a circuit detecting GHz signals is required. Here 0.22 µF disk capacitor is used to capture the RF signals from the mobile phone. This along with the leads act as a small GHz loop antenna to collect the RF signals.

13. WORKING PRINCIPLE : One lead of the capacitor gets DC from the positive rail and the other lead goes to the negative input of IC. The capacitor gets energy for storage. This energy is applied to the input of the IC . So the inputs of IC is almost balanced and output is almost zero. But at any time IC can give a high output if a small current is induced to its inputs .

14. WORKING PRINCIPLE : There is a natural electromagnetic field around the capacitor caused by the 50Hz from electrical wiring. When the mobile phone radiates high frequency radiation, capacitor oscillates and release energy in the inputs of IC. This oscillation is indicated by the flashing of the LED.

15. WORKING PRINCIPLE : In short, capacitor carries energy and is in an electromagnetic field. So a slight change in field caused by the RF signals from phone will disturb the field and forces the capacitor to release energy. The LED blinks until the signal ceases.

16. APPLICATIONS OF CELL PHONE DETECTOR: This circuit can be used to detect the presence of active cell phones at examination halls and meetings. It can be used to detect active cell phones in Hospitals, Petrol pumps, Court of law and Military bases.

17. CONCLUSIONS: Though the device is handy, it has its own pros and cons just like other devices. Pros: The device is sensitive to even channelize other RF signals belonging to other devices other t han cell phones like radios. It can be used for detecting cell phones used for spying and transmission of unauthorized audios and videos.

18. THANK YOU Cons: It is a short range detector, of the order of centimeters. The presence of this device would jam the signals of other devices due to the fluctuations.

19. THANK YOU