Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Cell Phone Detector

Cell Phone Detector

This is a mobile phone sniffer circuit that can detect the signals being used in the GSM band at about 900 MHz. Since the signals are digitally encoded, it can detect only the signal activity, not the speech or the message contents. A headphone is used to hear the detected signals.
The circuit schematic is given in the .rar archive attachment. There are two separate detector units. Every detector unit consists of a dipole antenna, a choke and a diode. The antenna receives the GSM signals in the medium. Then a small amount of charge is induced in the choke. The diode demodulates the signal and finishes detecting. The diodes must be schottky diodes or germanium diodes. Since the forward voltage of a silisium diode is high, it won’t give a sufficient result in this circuit.

LM358 amplifies the received signal. It contains two separate op-amps that are supplied by a common power source. R3 and R7 resistors determine the gain of the amplifiers. When the resistor values are greater than 10M then the noise level increases.

So there are four pieces of antenna and each one is about 8.3 cm long. The wire type is not critical but its better to choose a fairly thick wire that will not bend too easily. It is a 1.5 mm diameter wire seen in the photo that we used. The two antennas must be positioned perpendicularly.

Visit Here for more.







 

More Articles to Read

App note: EPIC: Electro-Pyrotechnic Initiator Chip Resistor
App note: EPIC: Electro-Pyrotechnic Initiator Chip Resistor
App note: Noise analysis for high-speed op amps
App note: Noise analysis for high-speed op amps
Skill Sunday: Arrays
Skill Sunday: Arrays
App note: Infrared remote control implementation with MSP430FR4xx
App note: Infrared remote control implementation with MSP430FR4xx
Gesture Controlled Smart Home
Gesture Controlled Smart Home
Design for a Wideband, Differential Transimpedance DAC Output
Design for a Wideband, Differential Transimpedance DAC Output
Wrist thrusters let you fly through the water effortlessly
Wrist thrusters let you fly through the water effortlessly
Bertan/Spellman 225-20R HV power supply teardown
Bertan/Spellman 225-20R HV power supply teardown
Blinking Christmas Lights
Blinking Christmas Lights
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adjusting clock with alarm, hygrometer & thermometer on 1.8″ ST7735 display
Adding an “extra sense” with rangefinders
Adding an “extra sense” with rangefinders
This wireless game controller looks like a rug
This wireless game controller looks like a rug
How to run your ESP8266 for years on a battery
How to run your ESP8266 for years on a battery
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Calibration of a 3-Phase Energy Meter Board on the ADE7754
Making beats on a tiny Arduino DJ controller
Making beats on a tiny Arduino DJ controller
Qinsi-QS5100 Sn63Pb37 solder profile
Qinsi-QS5100 Sn63Pb37 solder profile
Water Detection System
Water Detection System
Professional Hi-Fi 15W Tube Amplifier circuit
Professional Hi-Fi 15W Tube Amplifier circuit
This Arduino machine will judge how sick your ollies are
This Arduino machine will judge how sick your ollies are
Turn an old payphone into a boombox for ’90s hits
Turn an old payphone into a boombox for ’90s hits

Top


Shares