Mobile cell phone detector (sniffer) circuit diagram: engineering and diploma project

Posted on Feb 5, 2014

Here is a simple engineering project circuit of handy mobile cell phone detector (sniffer). This pocket-sizedmobile communication detector or sniffer can sense the existence of a mobile device. So it can be used to avoid the use of mobile phones in private rooms, examination halls, etc. It is also useful for detecting the use of mobile phone for s

Mobile cell phone detector (sniffer) circuit diagram: engineering and diploma project
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pying and other related activities. 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. The instant bug detects RF (Radio Frequency) transmission signal from a mobile phone, it produces a beep sound alarm. The circuit is able to detect all forms of mobile phone activity even when it is in silent mode. The circuit is designed as a sensitive RF detector. The RF signal diode 1N3491 forms the major element. Output signal from the diode is pre amplified by the transistor BFR96. It is a high frequency (Microwave frequency) low power transistor with huge current gain (approximately 15dB at 0. 5GHz) and bandwidth. The pre amplified signal is fed to next amplifier stage built around IC TL071, it is a low noise JFET input op amp with low input bias and offset current. The biFET technology gives high slew rate to the IC. The next potentiometer is used to vary the signal amplitude, then it is fed to amplifier stage built around IC LA4440, it is a two channel audio power amplifier with inbuilt dual channels for stereo and bridge amplifier applications. In dual mode the IC LA4440 gives 6W, where as in bridge mode it provides 19W. It has good ripple rejection of 40dB, small residual noise, built in over voltage and surge voltage protection, and pin to pin protection. The RF reception and performance of the circuit is dependent on many...

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