## Noise Meter

Noise pollution is tends to many non-communicable diseases and. Safe level of noise is considered up to 30 dB. Here is a interesting circuit by dreamlover technology, "Noise Meter" used to measure the level of noise indicting by LED and in addition it give warning when noise crosses the safe level of 30 dB by beeping sound.

### Circuit description of Noise meter

The entire circuit of noise meter has been designed and fabricated using sound intensity sensor and display unit. Here condenser microphone is used as sensor  of noise meter with operational amplifier (IC2) and corresponding passive components. The inverting and non-inverting input is given to operational amplifier IC (IC2) from pin 2 and pin 3 respectively. Where output from pin 6 of IC2 is connected to the inverting input for negative feedback through resistor R5. The controlling sound ac signal from potentiometer VR1 is first rectified by diode (D1 and D2) and maintains it at the output level of IC2.

The display unit is designed around monolithic IC LM3914 (IC3). It drives ten LEDs by sensing analog voltage. Each LED is connected to output of IC3 represents the sound level of 3 dB in descending order from 18 to 10. The glowing all ten LEDs indicate sound intensity is 30dB.

The PNP transistor get base bias when output at pin 10 of IC3 goes low to drive the piezo buzzer in order to give sound. This indicates noise crosses the safe level of 30 dB.

#### PARTS LIST

Resistors (all ¼-watt, ± 5% Carbon)

R1, R3, R4, R7 = 10 KΩ

R2 = 12 KΩ

R5 = 10 MΩ

R6 = 27 KΩ

R8 = 4.7 KΩ

R9 = 1 KΩ

R10 = 5 KΩ

VR1 = 1 KΩ

C1 = 1000 µF/25V

C2, C3 = 0.1 µF

C4 = 0.22 µF

C5 = 4.7 µF/16V

C6 = 1 µF/16V

C7 = 2.2 µF/16V

#### Semiconductors

IC1 = 7809 (voltage regulator)

IC2 = CA3130 (operational amplifier)

IC3 = LM3914 (monolithic IC)

D1, D2 = 1N4148

D3 = 1N4001

T1 = BC558 (PNP)

#### Miscellaneous

LED1 – LED4 = Green

LED5 – LED7 = Yellow

LED8 – LED10 = RED

MIC1 = Condenser microphone

PZ1 = Piezo buzzer

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## 33 thoughts on “Noise Meter”

1. if IC2 = CA3130 (operational amplifier) is out in the market or any merchandise, can i use CA3140? or any compatible or substitute for this operational amplifier?

1. IC2 = CA3130 is a 15MHz BiMOS Microprocessor Operational Amplifiers with MOSFET Input/CMOS Output.
And CA3140 is a 4.5MHz BiMOS Operational Amplifier with MOSFET Input/Bipolar Output.

Theoretically CA3140 should also work with the circuit. Another replacement option can also be HCA10014 it is a 15MHz BiMOS Operational Amplifier with MOSFET Input/CMOS Output.

1. Anonymous says:

tnx…but can i use other op amp other than that, that is most available?

1. Yes sure ; Theoretically you can use any operational amplifier but with the change in op-amp you might also want to change the values of R2 ; R5 and C4 correspondingly by using the Hit and Trial method and analyzing the output.

2. Anonymous says:

pls suggest if theres other ic we can place to ca3130..other than HCA10014….for more option…. thank u so much!

1. As I said earlier you can also use any Op-Amp but but with necessary adjustments in the circuits.
I would also like to hear to your experience of using Op-Amps other than CA3130 if you do so.

3. Anonymous says:

i use this noise meter for my proposal to my electronic final term…i cant start cause IC2 is not available….and im an electrical engr. thats why i dont know what to do or what alternative should i buy…to start immediately to my project…

4. Anonymous says:

so CA3140 can be replacement for CA3130 in this noise meter? thank you ^_^ ssoooo mmmmuuccchhh…

5. Atreya says:

I dont find the configuration of VR1.Can you please give it

1. The part list is now updated with the value for VR1.

6. anonymous says:

pls tell me what should be the input voltage??

1. Because we are using a voltage regulator here voltage input from anywhere in the range 10-24 voltage should be ok.

1. a.m. juanta says:

ur circuits really applicable with our projects…we want to use it but theres a problem we need to apply it in amplifier..what should we can u help us…how can we apply it with amli we have already circuit for ampli with 3watts output how can we we fit ur design..tnx

7. mangesh says:

saale yeise project dalta hei ki jo chalte bhi nahi aur ter ko kuch sharam hey ki nahi ,….
Ek to sem chota hey.. Guide pagal jaisi mili hey,,, aur tere bharose project choda tha …. aur padhai kar rahe the,,,aur abhi project chal nahi raha ///

8. Anonymous says:

im having a problem with the proteus simulation of this circuit. the leds are lit inspite of the fact that the battery is removed. can you help me with it please

9. student says:

good project… and its working we made it. This is my project for MSc physics.

10. Anonymous says:

what will happen if I replace the microphne by LDR but i keep the same circuit ?

11. Nisha Robinson says:

The normal range of conversational sound is between 45 to 60,so is that possible to change the level represented by each LED from 3db to 10db or something so as to make it useful in a wide range.

12. Vijay Saayi says:

Can I get a bread board diagram of this circuit ?

13. anonymus123 says:

guys can we use instead lm3914 a lm3915 or lm3916? pls answer me

14. give design of noise meter with neat explaination

15. Leelavathi says:

Sir, can we use LED displays instead of LED’s ?

16. Leelavathi says:

If so then the components which are using are enough or we may need some other components?

17. Anonymous says:

if i wnt to use 40db then

18. i want to use 40db sound then what should i do

19. ajit says:

which ic shoud i use for 40db??

20. sachim says:

dd this work properly

21. Hamza khan says:

I want to use this circuit to detect the noise of students in class .. Can i increase the sound range from 30db to like 90db? Please help?

22. yashavant lokhande says:

what is the maximum level of the noise to be measured by this circuit ? in decibals.

23. yashavant lokhande says:

what should be add to the circuit if i want to set the zero & span of the noise level?

24. yashavant lokhande says:

if i want to measure the slight change in the noise level continously upto 120 decibals, then what should be done.

25. Anonymous says:

i made the circuit. but it detects voice level of 50 db and above.what would be the reason?