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