SOUND DETECTOR CIRCUIT PROJECT MEMBERS:
Syed Anis Badshah UW-09-ME-BE-001 UW-09-ME-BE-001 Abdul-Rafay
UW-09-ME-BE-010
Nadeem Riaz
UW-09-ME-BE-030 UW-09-ME-BE-030
Shafique Ahmad
UW-09-ME-BE-032 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 trial methods 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 bread board 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 1KΩ 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 100KΩ 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 OP- AMP in order to power it. A feed resistor of 100kΩ and load resistor of 1KΩ is implemented to the negative input of the OP-AMP. OP -AMP. It will give a gain of 101. So this will give us nice amplified audio signals. PROJECT REPORT
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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 voltage. Negative input of the comparator comparator is attached with 100KΩ resistor which is powered with 9V dc battery, and a second resistor of 10KΩ, 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 100Ω 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 DISADVANTAGES OF SOUND DETECTOR CIRCUIT The main problems with detecting sound are: i.
Electrets microphone inserts are low cost, but only produce a very small signal, which requires amplification
ii.
The background noise level can vary considerably, and so some form of calibration is required
iii.
Some noises, such as a hand-clap, are very quick and so can be ‘missed’ 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.
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