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Presents, audio sociables are normally used in many practical applications such as entering studios, public reference systems, sound support systems, broadcast medium, telecasting, and movie post-production. Audio sociable is an electronic device for commixture, routing, and altering the degree, timber or kineticss of audio signals in professional sound. With audio sociables, instrumentalists, sound applied scientists, disc jockeys ( DJs ) are able to unite multiple audio beginnings into one seamless and harmonious end product particularly DJs will happen them utile during public presentations at parties, concerts, and events where a uninterrupted mix of music is necessary.

1.2 Objective

The aim of this undertaking is to expose to technology system development procedure and to heighten the accomplishments and capableness of planing and building circuit, trouble-shooting, job analysis and work outing that required to plan and implement the sound sociable undertaking. Therefore, cognition that gained in Circuit Theory, Electronics I, Electronics II, Electronics III, needed in order to understand the circuit and operation of the circuit. In this undertaking, a basic sound sociable with human hearing scope 20HZ to 20k HZ is attempted to construct utilizing cardinal cognition on the operation of operational amplifiers and its application in cross attenuation, magnifying, and filtering.

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1.3 Work Plan

Activity

Wk 1

Wk 2

Wk 3

Wk 4

Wk 5

Wk 6

Wk 7

Lab 1 Operation Amplifier Basic

ten

Lab 2 Operation Amplifier Application 1

ten

Lab 3 Operation Amplifier Application 2

ten

Lab 4 Operation Amplifier Application 3

ten

Lab 5 Operation Amplifier Application 4

ten

Lab 6 Operation Amplifier Application 5

ten

Lab 7 Audio Mixer

ten

1.4 Design Methodology

No

Yes

Figure 1.1: Design methodological analysis and flow

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Figure 1.1 shows the design flow of the whole undertaking. An overall block diagram of the design is drawn to hold a general thought on the operation of the whole design. Following, appropriate circuits are studied and analyzed from the internet resources and related stuffs on their operations. A simple circuit schematic is drawn and checked by utilizing Pspice. When the conventional cheque passed, circuit design will be generated. If the simulation is failed, trouble-shooting and corrections need to be done so merely reiterate the simulation once more.

Last, a complete study or thesis about the undertaking will be written to enter the inside informations of the full undertaking.

1.5 Organization of Report

This study is organized into 5 chapters. In chapter 1, a brief debut on the audio sociable is provided. Chapter 2 introduces the backgrounds and circuit building of the basic amplifier circuits that need for audio sociable. Besides, its applications besides discussed in elaborate. Analysis and the treatment for each phase of the undertaking before uniting circuit will be discussed in chapter 3. Following, circuit design, circuit testing of basic audio sociable and jobs occurred during building will be discussed in chapter 4. Besides, chapter 4 besides introduces possible betterments which could be carried out in the following phase of undertaking. This study is concluded in chapter 5, which discoursing the concluding result of undertaking.

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Chapter 2: BACKGROUND AND CIRCUIT CONSTRUCTION

2.1 Basic amplifier circuits

At first, operational amplifier ( op A ) could be modified by external circuitry easy to execute mathematical operations such as add-on, integrating and so on in analog-computer applications. Nevertheless, op As have become more dependable, miniaturized, temperature-stabilized and really utile in broad scope of applications such as summing amplifier, electromotive force follower, comparator and active filter with the coming of solid-state engineering.

Figure 2.1: Op amp 741 pin connexions

Figure 2.1 above shows the pin connexions of op A 741.Notice that there is a point in the corner, or notch at the terminal of the bundle which identifies the terminal from which to get down numbering the pin Numberss.

The ideal op-amp would be expected to hold the undermentioned of import features:

1 ) Infinite input electric resistance, .

2 ) Zero end product electric resistance, .

3 ) Infinite open-loop electromotive force addition, .

4 ) Infinite bandwidth, AOL remains unchanged from DC to really high frequence.

5 ) Zero offset electromotive force, zero input ( V+=V- ) produces zero end product.

6 ) Infinite common-mode rejection merely amplifies electromotive force difference between non-inverting and inverting input.

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The features above in bend form the footing for two cardinal regulations of an ideal op-amp which is called as the aureate regulations. The aureate regulations are idealisations of op A behaviour.

However, they are really utile for depicting overall public presentation however since they are applicable whenever op As are configured with negative feedback. See the aureate regulations to be exact when ideal op amp behaviour is assumed. Following are two simple statements of the aureate regulations:

No current flows into either of the input terminus

There is no electromotive force difference between the two input terminuss

2.1.1 Voltage Follower/Buffer

Figure 2.2: Voltage Follower/Buffer

Voltage follower or buffer is shown in Figure 2.2. From the equation, closed loop addition ACL is merely dependent on the ratio of RF and R1.Besides, the closed cringle addition ACL becomes one or integrity when RF goes to zero and R1 attacks eternity from the above equation. Isolating belongingss including high input electric resistance and highly low end product electric resistance doing an amplifier of integrity addition called as a buffer. In add-on, it has the best bandwidth of any op A circuit. Voltage follower provides effectual isolation of the end product from the signal beginning that doing really small power is drawn from the signal beginning. Therefore, lading consequence is eliminated.

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2.2 Operation Amplifier applications

2.2.1 Summarizing Amplifier

Summarizing amplifier multiple input signals in any proportion desired and is normally called as a signal sociable since it is used to unite audio signal from several inputs such as mikes, guitar, tape recording equipments and so on to supply a individual end product. Summarizing amplifier can be categorized into two types that are inverting amplifier and non inverting amplifier.

Figure 2.3: Inverting summer

Figure 2.3 above shows an inverting summer. From the equation above, if, so the end product is the amount of both the inputs inverted where.

2.2.2 Comparator

Comparator is a device which compares two electromotive forces or currents and switches its end product to bespeak which is larger. In other words, it provides an end product signal that stays high while the input signal is higher than the mention signal or threshold. When the input signal alterations somewhat, comparator is utile

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in supplying a big alteration in end product signal. Besides, it can be used to change over an linear signal into a digital signal.

Figure 2.4: Comparator

2.2.3 Crossfader

Crossfader is used to implement smooth passages between two music beginnings. On a DJ sociable, crossfader is fundamentally maps like two faders connected side-by-side, but in opposite waies to let DJ to melt one beginning out while melting another beginning at the same minute. The crossfader would maintain changeless end product degree in the perfect instance but there is no customary on how this should be achieved. Most crossfaders are variable resistances where merely two terminuss of potentiometer which are one side and the wiper are being used. At the terminal of variable resistance, the input signals are connected. The wiper which is 3rd contact slides between the terminal contacts as the crossfader boss is tuned. Crossfader is merely a summing amplifier.

The end product electromotive force of crossfader is expressed as supra where as in below Figure 2.5.

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Figure 2.5: Crossfader

2.2.4 3-band Graphic Equalizer

Figure 2.6: 3-band Graphic Equalizer

There are many sorts of equalisation which each of them has a different form of fading or encouragement. 3-band Graphic Equalizer is shown in the Figure 2.6. The in writing equaliser is developed to equalise the sound of a room and

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a sound system ‘s frequence response. They are widely seen in in-between and high terminal stereo sound systems and other consumer merchandises. Graphic equaliser consists of a bank of skidders for hiking and cutting different sets or frequence scopes of sound and they are used to rectify the decreased degree of high frequences in early telephone systems every bit good as in modern digital telephone systems and in single channels of a blending board, where the sound wave form is being applied with equalisation.

2.2.5 Voltage Level Indicator

Figure 2.7: Voltage degree index

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Voltage index is a electromotive force comparator which is shown in the Figure 2.7. It is used to compare two signals or in the instance here it is used to cognize whether it is exceeds the thresholds electromotive force. Several comparators portion a common input and each of the comparator is so supplied with a different mention or triping electromotive force. The mention electromotive force to each comparator is merely a simple electromotive force splitter. When the inputs exceed the mention electromotive force, the LED will be turned ON.

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Chapter 3: Analysis and Discussion

Before uniting all the circuits, each phase of the basic sound sociable has been tested so that mistakes and noises can be reduced when uniting the circuit.

3.1 Voltage Follower/Buffer

CH2 CH1

Figure 3.1: Input signal and end product wave form of buffer

For CH1: Vin = 2 – 0.5V/div = 1V

For CH2: Vout = 2 – 0.5V/div = 1V

Voltage addition, Av = Vout / Vin = 1

Percentage of mistake = 0 %

The consequence is satisfied as the per centum of mistake between theoretical and experimental consequence is zero.

3.2 Inverting Summer

CH1 CH2

Figure 3.2: Input signal and end product wave form of inverting summer

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For CH1: Vin = 2 – 0.5V/div = 1V

For CH2: Vout = 5.2 – 1V/div = 5.2V

Theoretical consequence for Vout = ( -Rf / R1 ) *Vin1 + ( -Rf / R2 ) * Vin2

= ( -5k / 1k ) ( 1 ) + ( -5k / 10k ) ( 1 )

= 5.5 V

Percentage of mistake = [ | 5.2 – 5.5 | / 5.5 ] – 100 %

= 5.45 %

The consequence is rather satisfied as the per centum of mistake between the theoretical and experimental consequence is merely 5.45 % .

3.3 Crossfader

CH2 CH1

Figure 3.3: Output wave form of crossfader when connect both input Vin1 and Vin2

For CH1: Vin = 1 – 1V/div = 1V

For CH2: Vout = 3.8 – 5/div = 19V

Av = 20 log ( Vout / Vin ) = 20 log 19

= 25.58

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Figure 3.4: Output wave form of crossfader when V- is set to focus on place

3.4 3-band Graphic Equalizer

Frequency ( kilohertz )

0.2

0.4

0.6

0.8

1

3

5

7

10

20

40

60

Vin, pp ( V )

1

1

1

1

1

1

1

1

1

1

1

1

Vout1 ( V )

0.71

0.70

0.60

0.50

0.44

0.17

0.10

0.074

0.052

0.026

0.014

0.010

Vout2 ( V )

0.155

0.28

0.39

0.48

0.54

0.66

0.54

0.45

0.34

0.195

0.106

0.074

Vout3 ( V )

0.042

0.08

0.12

0.156

0.20

0.48

0.62

0.68

0.68

0.52

0.31

0.215

Av1 ( dubnium )

-2.97

-3.1

-4.44

-6.02

-7.13

-15.39

-20.00

-22.62

-25.68

-31.70

-37.08

-40.00

Av2 ( dubnium )

-16.19

-11.06

-8.18

-6.38

-5.35

-3.61

-5..35

-6.94

-9.37

-14.20

-19.49

-22.62

Av3 ( dubnium )

-27.54

-21.94

-18.42

-16.14

-13.98

-6.38

-4.15

-3.35

-3.35

-5.68

-10.17

-13.35

Table 3.1 Frequency response of 3-band in writing equaliser ( Rf = 0? )

Frequency ( kilohertz )

0.2

0.4

0.6

0.8

1

3

5

7

10

20

40

60

Vin, pp ( V )

1

1

1

1

1

1

1

1

1

1

1

1

Vout1 ( V )

7.40

7.40

6.50

5.40

4.60

1.80

1.08

0.76

0.53

0.27

0.132

0.084

Vout2 ( V )

1.54

2.90

4.20

5.20

5.90

7.30

6.00

5.00

3.70

2.00

1.020

0.630

Vout3 ( V )

0.44

0.88

1.30

1.70

2.15

5.40

7.00

7.70

7.70

5.80

3.000

1.800

Av1 ( dubnium )

17.38

17.38

16.26

14.65

13.26

5.11

0.67

-2.38

-5.51

-11.37

-17.59

-21.51

Av2 ( dubnium )

3.75

9.25

12.46

14.32

15.42

17.27

15.56

13.98

11.36

6.02

0.170

-4.010

Av3 ( dubnium )

-7.13

-1.11

2.28

4.61

6.65

14.65

16.90

17.73

17.73

15.27

9.540

5.110

Table 3.2 Frequency response of 3-band in writing equaliser ( Rf =10k? )

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Graph 3.1: Frequency response of 3-band in writing equaliser ( Rf = 0? )

Graph 3.2: Frequency response of 3-band in writing equaliser ( Rf =10k? )

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3.5 Voltage Level Indicator

Figure 3.5: Voltage degree index

The flag denotes the cathode. During circuit building, the anode and cathode pin of LED have to link right onto the bread board. During the experiment, the anode and cathode pin have been connect wrongly onto the bread board and it was found that all LEDs are ON one time connect to the power supply. After trouble-shooting and retracing the circuit, the job been solved. The LED was ON one by one by increasing the input electromotive force.

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Chapter 4: BASIC AUDIO MIXER DESIGN

4.1 Circuit Design

Voltage Level Indicator 3-band Graphic Equalizer Voltage Follower/ Buffer

Crossfader Summer

Figure 4.1: Circuit building for the sound sociable

The circuit was design where the electromotive force degree index do non connected to the buffer which has connected to the talker every bit good because the end product electromotive force from the buffer could non back up both of the electromotive force degree index and talker at the same clip. This may due to non adequate power providing to the connexion. So, the electromotive force degree index was connected straight to the end product terminus of the inverting summer.

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Figure 4.2: Audio sociable design block diagram

4.2 Circuit Testing

Equalizer Sets

Lower Cutoff Frequency ( Hz )

Centre Frequency ( Hz )

Upper Cutoff Frequency ( Hz )

Bass

159.1549

344.8357

530.5165

Midrange

1989.4368

3942.0322

5894.6275

Soprano

4232.8442

8387.3025

12541.7607

Table 4.1: The frequence response of the equaliser sets

The soprano controls the high tones, center controls the mid-range tones and bass controls the low tones. The commixture of two vocals sounded nicer when bass, in-between and soprano were tuned to the minimal degree. Once tuning larger the three sets, quality of the sound is acceptable at the beginning until certain scope, the sound became noisy and particularly tuning the soprano into upper limit, the vocals were non sounded in perfect pitch and were really noisy.

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Figure 4.3: End product wave form when bass, in-between and soprano were tuned to minimum

Figure 4.3 shows the end product wave form when bass, in-between and soprano were tuned to minimum. There was no cutting for end product wave form when the bass, in-between frequence and soprano were tuned off.

niping

Figure 4.4: End product wave form when merely bass was tuned to the maximal degree

The end product wave form where merely bass was tuned to maximum degree is shown in Figure 4.4.There was niping at upper and lower portion of the end product wave form. When an amplifier overdriven and efforts to present an end product electromotive force or current beyond its maximal capableness, cutting is occurs and it is a signifier of waveform deformation. Bass set consists of more cutting compared to middle set and soprano set as the scope of frequence covered by the bass set is smaller which is shown in Table 4.1.

niping

Figure 4.5: End product wave form when merely center was tuned to the maximal degree

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Figure 4.5 shows the end product when merely center was tuned to the maximal degree and it was observed that there was niping at upper portion of the wave form. However, there was lesser cutting at the bottom portion of the end product wave form compared to the end product wave form of bass set. This may due to the in-between set covers scope of frequences from 1989.4368Hz boulder clay 5894.6275Hz which is much higher than bass set. Therefore, the cutting has become smaller.

niping

Figure 4.6: End product wave form when merely soprano was tuned to the maximal degree

It was observed that there was no cutting at the lower portion of the wave form merely soprano was tuned to the maximal degree which is shown in Figure 4.6. This may due to soprano set screen higher scope of frequences from 4232.8442Hz to 12541.7607Hz which is shown in Table 4.1 compared to bass and middle.

4.3 Discussion

At the get downing phase of the undertaking, the circuit constructed was rather mussy, this made trouble-shooting more hard. After retracing the circuit by cut downing the length of jumper wires, the mistake can be traced easier. As the undertaking traveling on, more experience gained from the mistake and careless error that had been made. Therefore, excess attention will be taken during building the circuit.

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During circuit testing, it was found that noises, deformation and loading effects were occurred. In order to cut down the noise and deformation, circuit may be modified by adding higher set from original 3-band to more set in following phase of the undertaking so that clearer sound with human hearing scope 20HZ to 20k HZ can be produced.

Besides that, throughout the undertaking, it was found that some of the end products of the potentiometers were non consistent doing the right consequence could non be achieved. It was observed that the end product wave form of the crossfader was distorted when uniting the circuit. However, there was no any connexion mistake after trouble-shooting the circuit many times until the potentiometer of the crossfader has been soldered wires. The job has been solved after soldering the wires and coveted consequences were managed to be achieved. Therefore, enforcement to the soldered wires were done as to guarantee that more stable end product and robust construction can be achieved due to the incompatibility in the end product of quality of the potentiometers.

During the testing phase, it is observed that there are some connexion mistakes in the bread board when uniting the circuit.Besides, the constituents ‘ legs and jumper wires did non inserted decently into bread board doing no sound produced from talker. However, with forbearance in trouble-shooting and excess attending, the connexion mistake would non be a major obstruction to continue with the testing processs and assembly stairss.

Future efforts of this undertaking is to build the circuit on the PCB board to increase the dependability of the circuit as PCB does non utilize the jumper wire and the connexion loss job can be eliminated and the messy circuit job can be solved. As a consequence, size of the circuit can be reduced by utilizing PCB for the circuit building. Unlike a bread board, PCB is designed every bit smaller as we can and will cut down the cost of the circuit. Furthermore, the following phase of this undertaking is seeking to plan power supply so that audio sociable can be operated easy in place or where else.

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Chapter 5: Decision

The undertaking of basic sound sociable was able to be completed within 7 hebdomads. Although there were a batch of barrier met, we had successful to get the better of them with attempt and patient. Skills such as trouble-shooting the hardware, circuit designing and implementing accomplishment are gained throughout the undertaking. Therefore, the aim of this undertaking which expose to technology system development procedure and to heighten the accomplishments and capableness of planing and building circuit, trouble-shooting, job analysis and work outing that required to plan and implement the sound sociable undertaking has been achieved. Overall, the design specifications of the sociable has been met and surpassed in certain countries.

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