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Noise Level Alarm
Noise pollution can cause hearing loss, hypertension, heart disease, annoyance, sleep disturbance and decreased performance in schools. Build this kit and set the threshold level for the noise and get informed whenever the sound gets exceeded the desired limit and thus prevent damage to the health.
Noise level monitoring gives a brief hands on concept of cascaded and three stage amplifiers in analog electronics and amplifying a very small signal with high gain transistors
Things which you can learn:
1. Cascaded three stage amplifier
2. Analog electronics
3. Gain in transistors
4. Condensor mic
Noise is a serious environmental problem that affects us in our daily life. There is scientific evidence supporting that noise exposure can cause hearing loss, hypertension, heart disease, annoyance, sleep disturbance and decreased performance in schools. Sound-level indicators like the one presented here can help address this problem. This sound-level indicator monitors the sound level and indicates through an LED when the level is above the preset value.
The sound is captured by microphone MIC1 and amplified by first stage high-gain transistor T1. Trimmer potentiometer VR1 is used to adjust the threshold level. the signal is amplified again with second-stage transistor T2. This amplified signal is rectified by diode D1 and the charge is stored in capacitor C10. Diode D1 should preferably be a small-signal Schottky diode such as BAT81, BAT82, BAT83, BAT85 or better. You can use 1N4148 and 1N914 also but the signal from the input should be stronger.