sound detector circuit term project report

7/31/2019 sound detector circuit term project report

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PROJECT REPORT P a g e | 1

SOUND DETECTOR CIRCUIT

PROJECT MEMBERS:

Syed Anis Badshah UW-09-ME-BE-001Abdul-Rafay UW-09-ME-BE-010Nadeem Riaz UW-09-ME-BE-030Shafique Ahmad UW-09-ME-BE-032

Wah Engineering College

UNIVERSITY OF WAH

25 JAN, 2012


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DEDICATIONS

This project is dedicated to our parents and Teachers without

whose support and prayers we are nothing.


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ACKNOWLEDGEMENT

First of all we would like to thank Allah Almighty for giving us the chance and

the courage to carry out this project. Although the it is not carried on PCB (wire

board) but we have achieved this on bread board.

Secondly, we would like to thank our Supervisor Engr; Salma for all the

support and guidance without which we would have never gone so far.

Thirdly we would like to thank WEC lab Staff for their technical advices.

We would like to thank Engr; Khuram Shehzad for establishing theoretical

concepts.


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ABSTRACT

Looking at the present security and tracing systems; we get an idea of the

importance of alternate ways of getting detecting sound. One of the simpler and

cheaper one of these methods is the sound detector sensor circuit. In this method a

Microphone of high sensitive is used to detect sound and is coupled with an op-amp to

amplify the signal amplitude and then combined with the output source like speaker,

buzzers, timer, LED or tracer. One such circuit for security generation was desired.

The part of the project that is presented here only deals with the sound detecting. The

circuit was designed except for the microphone part which was built on hit and trialmethods as has been done in nearly all experimental circuits since the calculations

involved are too difficult. The theoretical calculations of the circuit were done along

with the position analysis of the OP-AMP and the values sorted were used to design

the circuit. The analysis of the circuit was done as a comparator and based on this the

design was finalized. The design is still being in a prototype form on bread board, but

due to not too much familiarity with Electronics, the circuit is implemented on breadboard and not on wire board (PCB).


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INTRODUCTION

This is a simple circuit that can detect sounds by using a common condenser

microphone. Sensitivity is variable. The circuit's output becomes high each time as

sound is detected; otherwise it is in low level. You can use it in simple robots for

sound responding (e.g. reaction -> when you clap your hands). This circuit recognize

human voice as a common sound (you can't use it for voice recognition).

Our implemented project circuit diagram is given below.

The circuit is very simple and has totally 3 stages:

The microphone stage.

The amplification stage. The comparator stage.

1. Microphone stage:The microphone stage captures the sound and converts it to electrical

signal. A 9V battery source is connected through 1K resistance to the

Microphone in order to power it.The circuit diagram, with block indicates this stage.


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Next the signal goes through a high pass filter, comprising of 0.1micro farad

capacitor and 100K resistor. Its purpose is to remove the 9V dc offset.

The circuit diagram for this is given below;

2. Amplification stage:

The amplification stage amplifies the signal. The amplifier used here is

LM324N, and is utilized as non-inverting amplifier. A 9V dc secondary source

is applied to the OP-AMP in order to power it. A feed resistor of 100k and

load resistor of 1K is implemented to the negative input of the OP-AMP.

It will give a gain of 101. So this will give us nice amplified audio signals.


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The circuit with block diagram is shown below.

3. Comparator stage.

The comparator changes the output level if the amplified signal is higher from

the reference voltage.Negative input of the comparator is attached with 100K

resistor which is powered with 9V dc battery, and a second resistor of 10K,

which is grounded. As shown in following figure.


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So when the amplified sound crosses the 0.45V thresholds the comparator will go high

and turn the LED on. The 100 resistor is connected before the LED on the output in

order to control the access of current. We can change the thresholds value for more or

less sensitive the circuit.

Graph of the whole circuit detecting sound signal is given below.


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The sound detector circuit is used for;

i. Security system for your house, office, or store.

ii. Statistics on barking dogs.

iii. Automate simple scripts for the house and school projects.

iv. Automate notification upon detection of sound.

v. Use as door bell.

vi. As a spy purposes.

vii. As a source to overcome the cheating in exams.

DISADVANTAGES OF SOUND DETECTOR CIRCUIT

The main problems with detecting sound are:

i. Electrets microphone inserts are low cost, but only produce a verysmall signal, which requires amplification

ii. The background noise level can vary considerably, and so some formof calibration is required

iii. Some noises, such as a hand-clap, are very quick and so can bemissed with some electronic circuits (e.g. when using a

microcontroller)


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CONCLUSIONS:

Through this term project, I got a lot of concepts relating to electronics and

especially to sensors, like rain sensor, light sensor, dark sensor. I got fully

command over OP-AMPS when treating as OP-AMP and as a comparator.

I got how gain is produced through amplification and how in thresholds voltage

changes, the intensity of output is affected.

sound detector circuit term project report

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