Mobile Scanner. Start Up Project 35

2AKeep this Match box size Mobile Scanner in your pocket. It will Scan around you and beeps loudly when a Mobile phone turns active in your vicinity. It can detect the activation of Mobile phone around 2 Meters radius. It beeps during incoming call, outgoing call and when somebody tries to take your Photo. It is an ideal device to detect Mobile phone use in examinations halls, confidential rooms, hospitals etc where Mobile phone is strictly prohibited. Its range can be from 50 cm to 3 meters depending on the type of the active Mobile phone. With  Smart phones, its range is less than 1 meter because there is a mechanism in it to prevent excess radiation. But in ordinary Mobile phones, its range can be up to three meters. Try this nice weekend project.
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Audio Amplifier Design

An Audio amplifier needs to give an output waveform exactly similar to the input waveform even though the output is amplified. Op Amps are widely used to amplify signals mainly in the Preamplifier stage. The input can be signal from an audio device or from a microphone. The Pre Amplifier stage uses either a Non inverting amplifier or Inverting Amplifier. This note will help you to design an amplifier based on JFET input Op Amp TL0 71.

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