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The entire circuit is complex. The block diagram makes the circuit easy to understand. We divide the circuit in several blocks. The function of each block discussed below

1. Microphone takes the voice signal as input.

2. HPF is used for noise reduction purpose.

3. Amplifier amplifies the signal 100 times.

4. Peak Detector holds the signal for a few mille seconds.

5. Comparator compares the signal voltage with a fixed reference voltage.

6. Comparator output activates the LED / Alarm