This sound scanner circuit will scan the sound vibration present near the vicinity and convert them into audible sound or beeps to alert you. Many of us live alone in home and always fear that somebody is walking in the corridor especially in nights. So, to solve this, just install this circuit in your sit outs, car porch and many other places in your house. So when ever any person walk around microphone it will pick up the sound and will give you beep sound to alert you. The main advantage of this circuit is it can detect vibration up to a distance of 3 meters.
Fig. 1: Prototype of Sound Scanner Circuit on Breadboard
The sound scanner circuit comprises of Operational amplifier 741 which is used as a sensitive voltage comparator. IC1 is used to sense the sound signal present near the condenser microphone. And resistor R1 is used to increase the sensitivity of microphone. When vibration is picked up by the microphone it converts them into electrical signals and feed it to inverting terminal that is pin 2 of IC1 through capacitor C1 and resistor R2. Here capacitor C1 is act as a coupling capacitor. And adjust VR1 to get maximum gain. Now this signals from output pin 6 are feed to non-inverting pin 3 of IC2 through capacitor C2 .