02-07-2010, 12:29 AM
the presence of an activated mobile cellphone can be detected by using this cellphone ,pocket-size mobile transmission detector. The range can be upto one and-a-half metres. It can be installed in examination halls, confidential rooms, etc for detecting the use of cellphones. spying and unauthorised video transmission. etc can also be easily identified. incoming and outgoing calls, SMS and video transmission etc can be detected. moment the bug detects RF transmission signal , it indicates it either by a beep sound or flashing of an LED or both and remains on till the signal transmission stops. The mobile phones mobile phones uses frequencies that ranges from 0.9 to 3 GHz with a wavelength of 3.3 to 10 cm. Thus a mobile bug must detect signals in the gigahertz range. The circuit uses a 0.22microfarad disk capacitor to capture the RF signals from the mobile phone. The disk capacitor along with the leads acts as a small gigahertz loop antenna to collect the RF signals from the mobile phone. It contains a a current-to-voltage converter IC CA3130, a 555 IC, resistors, capacitors, transistor BC548.
The circuit is simple and all the components are easily available in electronic shops. This would make a good mini project. You can make the product as small as possible and enclose the project in a beautiful tiny box.
the working, circuit and other details can be obtained from these links:
http://electroschematics1035/mobile-bug-detector-sniffer/
http://dmohankumar.files.wordpress2010/0...ircuit.pdf