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A

Seminar Report

On

Bull horn Loudspeaker

Submitted in partial fulfillment of the requirement

For the award of the

Degree of

Bachelor of TechnologyIn

Electronics & Communication Engineering

Submitted by Under the supervision ofDrishti Dusad- 6EC-21 Sandeep Bairwea

Disha Shroff- 6EC-54

Nupur Purohit- 6EC-34

Department of Electronics Engineering

JAIPUR NATIONAL UNIVERSITYJAIPUR

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CERTIFICATE

This is to certify that Mr/Ms.a student of

B.Tech(Electronics & communication Engineering) 3rd year 6th semester has

submitted His/her Project entitled

BULL HORN LOUDSPEAKER under my guidance.

SANDEEP BAIRWEA

Project guide

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ACKNOWLEDGEMENT

I am grateful to have the opportunity to work with Mr. SANDEEP BAIRWEA and

Mr. YAGVALKYASHARMAdepartment of electronics and communicationengineering,

who had kept me on my toe and guided me at each step. Working under him was wonderful

experience.

I learned not only the technical aspects but also the practical qualities of working as a team.

I am highly inspired by his dedication to work, as he made continuous effort to

make this project successful.

I am grateful to Prof. S.K.Gupta, head of electronics & communicationdepartment, for giving

me this opportunity to work on the topic on this esteemed organisation.

I would like to express my gratitude towards my parents whose blessings are always with me.Their life time support and encouragement

has provided the basic foundation of any success,

we will ever achieve.

Drishti Dusad- 6EC-21Disha Shroff- 6EC-54

Nupur Purohit- 6EC-34

(3rd year, 6th sem ECE)

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ABSTRACT

The loudspeaker, forming a compact microphone amplifier primarily intended for speech

reinforcement. A device of this kind is particularly suited to teachers, lecturers, tourists' guides,

hostesses and anyone speaking in crowded, noisy environment. The circuit's heart is formed by the

TDA7052 Audio power amplifier IC, delivering a maximum output of 1.2W @ 6V supply. An

external microphone must be plugged into J1, its signal being amplified by Q1 and fed to IC1. R1

acts as a volume control and C3 tailors the upper audio frequency band, mainly to reduce the

microphone possibility of picking-up the loudspeaker output, causing a very undesirable and loud

"howl", i.e. the well known Larsen effect. Therefore, C3 value can be varied in the 4n7 - 22nF

range to ensure the best compromise from speech tone quality and minimum Larsen effect

occurrence. Dynamic or electrets microphone is warmly recommended. It has a useful feature that

can be used to momentarily mute the microphone This simple tone control (bass & treble control)

can be used in may audio applications. It can be added to amplifiers, used as a stand alone control

module, or even built into new and exciting instruments. It uses NE5532 IC but other ICs such as

LF353 or 4558 could be used as well. It requires dual +12V,-12V power supply.

By this circuit can fine the bass treble well, and fine the loud sound the light. get fine to

balance the sound everything is completed.

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List of figures page no.

1. EQUIVALENT SCHEMATIC & CONNECTION DIAGRAM 9

2. OUTLINE OF LM 386 10

3. LOUDSPEAKER 12

4. SYSTEM DESIGN 15

5. CIRCUIT DIAGRAM 31

CONTENT

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CHAPTER page no.

1. LM 386 ......7

1.1 GENERAL DISCRIPTION 7

1.2 FEATURES 81.3 APPLICATIONS 8

1.4 ELECTRICAL CHARACTERISTICS 10

1.5 APPLICATIONS 11

2. LOUDSPEAKER ...12

2.1 TERMINOLOGY 12

2.2 DRIVER DESIGN 13

2.3 LOUDSPEAKER SYSTEM DESIGN 152.4 SPECIFICATION 17

2.5 ELECTRICAL CHARACTERISTICS 18

3. HORN LOUDSPEAKER 19

3.1 MEGAPHONE 20

3.2 ELECTRIC MEGAPHONES 21

3.3 MEGAPHONE USES 22

4. MONO JACK SOCKET 234.1 MODERN CONNECTOR 244.2 MONO & STEREO COMPACTIBILITY 25

4.3 USES 27

4.4 SWITCH CONTACTS 29

5. CIRCUIT DISCRIPTION ..30

5.1 INTRODUCTION 30

5.2 CIRCUIT DIAGRAM 315.3 PARTS 32

5.4 PROCEDURE OF BUILDING LOUDSPEAKER 33

6. FUTURE WORK ..34

7. REFERENCES 35

Introduction

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Horns were the earliest form of amplification. Horns do not use electricity. Thomas Edison,

Magnavox, and Victrola all developed advanced and well-performing horns from 1880 to the

1920's. The problem with horns is that they could not amplify the sound very much. With the useof electrical amplification in the future loud sound could be generated to fill large public spaces.

Horns remain a novelty for collectors today.

. Horn loudspeakers use a shaped waveguide in front of or behind the driver to increase the

directivity of the loudspeaker and to transform a small diameter, high pressure condition at thedriver cone surface to a large diameter, low pressure condition at the mouth of the horn. This

increases the sensitivity of the loudspeaker and focuses the sound over a narrower area. The size of

the throat, mouth, the length of the horn, as well as the area expansion rate along it must becarefully chosen to match the drive to properly provide this transforming function over a range of

frequencies (every horn performs poorly outside its acoustic limits, at both high and low

frequencies). The length and cross-sectional mouth area required to create a bass or sub-bass hornrequire a horn many feet long. 'Folded' horns can reduce the total size, but compel designers to

make compromises and accept increased complication such as cost and construction. Some horn

designs not only fold the low frequency horn, but use the walls in a room corner as an extension ofthe horn mouth. In the late 1940s, horns whose mouths took up much of a room wall were not

unknown amongst hi-fi fans. Room sized installations became much less acceptable when two or

more were required.

A horn loaded speaker can have a sensitivity as high as 110 dB at 2.83 volts (1 watt at 8 ohms) at 1meter. This is a hundredfold increase in output compared to a speaker rated at 90 dB sensitivity,

and is invaluable in applications where high sound levels are required or amplifier power is

limited.

We have made Bull horn loudspeaker.The basic function of this project is given later. We have

used a IC LM386 for this purpose along with the capacitors which are used as filters . for input we

can use mic or any audio signal in this project we have used the audio source such as mobile with

the help of an 3.5mm socket. The complete description of project is given below.

Chapter1

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1. LM386Low Voltage Audio Power Amplifier

1.1 General DescriptionThe LM386 is a power amplifier designed for use in low voltage consumer applications. The gainis internally set to 20 to keep external part count low, but the addition of an external resistor and

capacitor between pins 1 and 8 will increase the gain to any value from 20 to 200. The inputs are

ground referenced while the output automatically biases to one-half the supply voltage. Thequiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the

LM386 ideal for battery operation.

1.2 Features Battery operation

Minimum external parts

Wide supply voltage range: 4V12V or 5V18V Low quiescent current drain: 4mA

Voltage gains from 20 to 200

Ground referenced input

Self-centering output quiescent voltage

Low distortion: 0.2% (AV = 20, VS = 6V, RL = 8, PO =

125mW, f = 1kHz)

Available in 8 pin MSOP package

1.3 Applications AM-FM radio amplifiers

Portable tape player amplifiers

Intercoms

TV sound systems

Line drivers

Ultrasonic drivers

Small servo drivers

Power converters

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Equivalent Schematic and Connection Diagrams

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1.4 Electrical Characteristics

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1.5 Application Hints

GAIN CONTROL

To make the LM386 a more versatile amplifier, two pins (1 and 8) are provided for gain control.

With pins 1 and 8 open the 1.35 k resistor sets the gain at 20 (26 dB). If a capacitor is put from pin

1 to 8, bypassing the 1.35 k resistor, the gain will go up to 200 (46 dB). If a resistor is placed inseries with the capacitor, the gain can be set to any value from 20 to 200. Gain control can also be

done by capacitively coupling a resistor (or FET) from pin 1 to ground. Additional external

components can be placed in parallel with the internal feedback resistors to tailor the gain andfrequency response for individual applications. For example, we can compensate poor speaker bass

response by frequency shaping the feedback path. This is done with a series RC from pin 1 to 5

(paralleling the internal 15 k resistor). For 6 dB effective bass boost: R . 15 k , the lowest value forgood stable operation is R = 10 k if pin 8 is open. If pins 1 and 8 are bypassed then R as low as 2 k

can be used. This restriction is because the amplifier is only compensated for closed-loop gains

greater than 9.

INPUT BIASING

The schematic shows that both inputs are biased to ground with a 50 kW resistor. The base current

of the input transistors is about 250 nA, so the inputs are at about 12.5 mV when left open. If the

dc source resistance driving the LM386 is higher than 250 kW it will contribute very little

additional offset (about 2.5 mV at the input, 50 mV at the output). If the dc source resistance is less

than 10 kW, then shorting the unused input to ground will keep the offset low (about 2.5 mV at the

input, 50 mV at the output). For dc source resistances between these values we can eliminate

excess offset by putting a resistor from the unused input to ground, equal in value to the dc source

resistance. Of course all offset problems

are eliminated if the input is capacitively coupled. When using the LM386 with higher gains

(bypassing the 1.35 kW resistor between pins 1 and 8) it is necessary to bypass the unused input,

preventing degradation of gain and

possible instabilities. This is done with a 0.1 F capacitor or a short to ground depending on the dc

source resistance on the driven input.

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Chapter2

2. Loudspeaker

A loudspeaker(or "speaker") is an electroacoustic transducerthat produces sound in response toan electrical audio signal input. Non-electrical loudspeakers were developed as accessories

to telephone systems, but electronic amplification by vacuum tubemade loudspeakers moregenerally useful. The most common form of loudspeaker uses a paper cone supporting a voice

coil electromagnet acting on a permanent magnet, but many other types exist. Where accurate

reproduction of sound is required, multiple loudspeakers may be used, each reproducing a part ofthe audible frequency range. Miniature loudspeakers are found in devices such as radio and TV

receivers, and many forms of music players. Larger loudspeaker systems are used for music, sound

reinforcementin theatres and concerts, and in public address systems.

2.1Terminology

The term "loudspeaker" may refer to individual transducers (known as "drivers") or to complete

speaker systems consisting of an enclosureincluding one or more drivers. To adequately reproducea wide range of frequencies, most loudspeaker systems employ more than one driver, particularly

for highersound pressure level or maximum accuracy. Individual drivers are used to reproduce

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different frequency ranges. The drivers are named subwoofers (for very low

frequencies); woofers (low frequencies); mid-range speakers (middle frequencies); tweeters (high

frequencies); and sometimessupertweeters, optimized for the highest audible frequencies. Theterms for different speaker drivers differ, depending on the application. In two-way systems there

is no mid-range driver, so the task of reproducing the mid-range sounds falls upon the woofer and

tweeter. Home stereos use the designation "tweeter" for the high frequency driver, whileprofessional concert systems may designate them as "HF" or "highs". When multiple drivers are

used in a system, a "filter network", called a crossover, separates the incoming signal into different

frequency ranges and routes them to the appropriate driver. A loudspeaker system with n separatefrequency bands is described as "n-way speakers": a two-way system will have a woofer and a

tweeter; a three-way system employs a woofer, a mid-range, and a tweeter. Loudspeakers were

described as "dynamic" to distinguish them from the earliermoving iron speaker, or speakers

usingpiezoelectric orelectrostatic systems as opposed to avoice coil that moves through a steadymagnetic field.

2.2 Driver design

The most common type of driver, commonly called a dynamic loudspeaker, uses a

lightweight diaphragm, orcone, connected to a rigid basket, orframe, via a flexible suspensionthat constrains a coil of fine tinsel wire to move axially through a cylindrical magnetic gap. When

an electrical signal is applied to thevoice coil, a magnetic field is created by the electric current in

the voice coil, making it a variable electromagnet. The coil and the driver's magnetic systeminteract, generating a mechanical force that causes the coil (and thus, the attached cone) to move

back and forth, thereby reproducing sound under the control of the applied electrical signal coming

from the amplifier. The following is a description of the individual components of this type ofloudspeaker.

The diaphragm is usually manufactured with a cone- or dome-shaped profile. A variety of differentmaterials may be used, but the most common are paper, plastic, and metal. The ideal material

would be 1) rigid, to prevent uncontrolled cone motions; 2) have low mass, to minimize startingforce requirements and energy storage issues; 3) be well damped, to reduce vibrations continuing

after the signal has stopped with little or no audible ringing due to its resonancefrequency as

determined by its usage. In practice, all three of these criteria cannot be met simultaneously using

existing materials; thus, driver design involves trade-offs. For example, paper is light and typicallywell damped, but is not stiff; metal may be stiff and light, but it usually has poor damping; plastic

can be light, but typically, the stiffer it is made, the poorer the damping. As a result, many cones

are made of some sort of composite material. For example, a cone might be made of cellulosepaper, into which some carbon fiber, Kevlar, glass, hemp orbamboo fibers have been added; or it

might use a honeycomb sandwich construction; or a coating might be applied to it so as to provideadditional stiffening or damping.

The chassis, frame, or basket, is designed to be rigid, avoiding deformation that could changecritical alignments with the magnet gap, perhaps causing the voice coil to rub against the sides of

the gap. Chassis are typically cast from aluminum alloy, orstamped from thin steel sheet, although

molded plastic and damped plastic compound baskets are becoming common, especially forinexpensive, low-mass drivers. Metallic chassis can play an important role in conducting heat

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http://en.wikipedia.org/wiki/Subwooferhttp://en.wikipedia.org/wiki/Wooferhttp://en.wikipedia.org/wiki/Mid-range_speakerhttp://en.wikipedia.org/wiki/Tweeterhttp://en.wikipedia.org/wiki/Supertweetershttp://en.wikipedia.org/wiki/Audio_crossoverhttp://en.wikipedia.org/wiki/Moving_iron_speakerhttp://en.wikipedia.org/wiki/Piezoelectric_speakers#Piezo_tweeterhttp://en.wikipedia.org/wiki/Piezoelectric_speakers#Piezo_tweeterhttp://en.wikipedia.org/wiki/Electrostatic_loudspeakerhttp://en.wikipedia.org/wiki/Voice_coilhttp://en.wikipedia.org/wiki/Diaphragm_(acoustics)http://en.wikipedia.org/wiki/Tinsel_wirehttp://en.wikipedia.org/wiki/Voice_coilhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Current_(electricity)http://en.wikipedia.org/wiki/Amplifierhttp://en.wikipedia.org/wiki/Absorption_(acoustics)http://en.wikipedia.org/wiki/Resonancehttp://en.wikipedia.org/wiki/Trade-offhttp://en.wikipedia.org/wiki/Carbon_fiberhttp://en.wikipedia.org/wiki/Kevlarhttp://en.wikipedia.org/wiki/Glass_(fiber)http://en.wikipedia.org/wiki/Hemphttp://en.wikipedia.org/wiki/Bamboohttp://en.wikipedia.org/wiki/Casting_(metalworking)http://en.wikipedia.org/wiki/Machine_presshttp://en.wikipedia.org/wiki/Subwooferhttp://en.wikipedia.org/wiki/Wooferhttp://en.wikipedia.org/wiki/Mid-range_speakerhttp://en.wikipedia.org/wiki/Tweeterhttp://en.wikipedia.org/wiki/Supertweetershttp://en.wikipedia.org/wiki/Audio_crossoverhttp://en.wikipedia.org/wiki/Moving_iron_speakerhttp://en.wikipedia.org/wiki/Piezoelectric_speakers#Piezo_tweeterhttp://en.wikipedia.org/wiki/Electrostatic_loudspeakerhttp://en.wikipedia.org/wiki/Voice_coilhttp://en.wikipedia.org/wiki/Diaphragm_(acoustics)http://en.wikipedia.org/wiki/Tinsel_wirehttp://en.wikipedia.org/wiki/Voice_coilhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Current_(electricity)http://en.wikipedia.org/wiki/Amplifierhttp://en.wikipedia.org/wiki/Absorption_(acoustics)http://en.wikipedia.org/wiki/Resonancehttp://en.wikipedia.org/wiki/Trade-offhttp://en.wikipedia.org/wiki/Carbon_fiberhttp://en.wikipedia.org/wiki/Kevlarhttp://en.wikipedia.org/wiki/Glass_(fiber)http://en.wikipedia.org/wiki/Hemphttp://en.wikipedia.org/wiki/Bamboohttp://en.wikipedia.org/wiki/Casting_(metalworking)http://en.wikipedia.org/wiki/Machine_press


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away from the voice coil; heating during operation changes resistance, causing physical

dimensional changes, and if extreme, may even demagnetize permanent magnets.

The suspension system keeps the coil centered in the gap and provides a restoring (centering) forcethat returns the cone to a neutral position after moving. A typical suspension system consists of

two parts: thespider, which connects the diaphragm or voice coil to the frame and provides themajority of the restoring force, and thesurround, which helps center the coil/cone assembly and

allows free pistonic motion aligned with the magnetic gap. The spider is usually made of acorrugated fabric disk, impregnated with a stiffening resin. The name comes from the shape of

early suspensions, which were two concentric rings ofBakelite material, joined by six or eight

curved "legs." Variations of this topology included the addition of a felt disc to provide a barrier toparticles that might otherwise cause the voice coil to rub. The German firm Rulik still offers

drivers with uncommon spiders made of wood.

The cone surround can be rubberor polyesterfoam, or a ring of corrugated, resin coated fabric; it

is attached to both the outer diaphragm circumference and to the frame. These different surround

materials, their shape and treatment can dramatically affect the acoustic output of a driver; eachclass and implementation having advantages and disadvantages. Polyester foam, for example, is

lightweight and economical, but is degraded by exposure to ozone, UV light, humidity andelevated temperatures, limiting its useful life to about 15 years.

The wire in a voice coil is usually made ofcopper, though aluminumand, rarely, silvermay be

used. The advantage of aluminum is its light weight, which raises the resonant frequency of the

voice coil and allows it to respond more easily to higher frequencies. A disadvantage of aluminumis that it is not easily soldered, and so connections are instead often crimped together and sealed.

These connections can corrode and fail in time. Voice-coil wire cross sections can be circular,

rectangular, or hexagonal, giving varying amounts of wire volume coverage in the magnetic gap

space. The coil is oriented co-axially inside the gap; it moves back and forth within a small circularvolume (a hole, slot, or groove) in the magnetic structure. The gap establishes a concentrated

magnetic field between the two poles of a permanent magnet; the outside of the gap being onepole, and the center post (called the pole piece) being the other. The pole piece and backplate are

often a single piece, called the poleplate or yoke.

Modern driver magnets are almost always permanent and made ofceramic,ferrite, Alnico, or,

more recently, rare earth such as neodymium and Samarium cobalt. A trend in designdue toincreases in transportation costs and a desire for smaller, lighter devices (as in many home theater

multi-speaker installations)is the use of the last instead of heavier ferrite types. Very few

manufacturers still produce electrodynamic loudspeakers with electrically powered field coils, as

was common in the earliest designs (one such is French). When high field-strength permanentmagnets became available, Alnico, an alloy of aluminum, nickel, and cobalt became popular, since

it dispensed with the power supply issues of field-coil drivers. Alnico was used for almost

exclusively until about 1980. Alnico magnets can be partially degaussed (i.e., demagnetized) byaccidental 'pops' or 'clicks' caused by loose connections, especially if used with a high power

amplifier. This damage can be reversed by "recharging" the magnet.

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After 1980, most (but not quite all) driver manufacturers switched from Alnico to ferrite magnets,

which are made from a mix of ceramic clay and fine particles of barium or strontium ferrite.

Although the energy per kilogram of these ceramic magnets is lower than Alnico, it is substantiallyless expensive, allowing designers to use larger yet more economical magnets to achieve a given

performance.

2.3 Loudspeaker system design

Crossover

Used in multi-driver speaker systems, the crossover is a subsystem that separates the input signal

into different frequency ranges suited to each driver. The drivers receive power only in their usable

frequency range (the range they were designed for), thereby reducing distortion in the drivers and

interference between them. No crossover can be perfect (i.e., absolute block at the edges of thepassband, no amplitude variation within the passband, no phase changes across the frequency band

boundaries the crossover establishes, ..), so this is an idealized description.

Crossovers can bepassive oractive. Apassive crossoveris an electronic circuit that uses acombination of one or more resistors, inductors, or non-polarcapacitors. These parts are formed

into carefully designed networks and are most often placed between the full frequency-range

power amplifier and the loudspeaker drivers to divide the amplifier's signal into the necessary

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frequency bands before being delivered to the individual drivers. Passive crossover circuits need

no external power beyond the audio signal itself, but have disadvantages: high cost, large

components (inductors and capacitors), limited ability to adjust the circuit as desired due to limitedchoice of high power level components, etc. They also cause substantial overall signal loss and a

significant reduction in damping factorbetween the voice coil and the crossover.[23] An active

crossoveris an electronic filter circuit that divides the signal into individual frequencybands before power amplification, thus requiring at least one power amplifier for each bandpass.[23] Passive filtering may also be used in this way before power amplification, but it is an

uncommon solution, being less flexible than active filtering. Any technique that uses crossoverfiltering followed by amplification is commonly known as bi-amping, tri-amping, quad-amping,

and so on, depending on the minimum number of amplifier channels. [24] Some loudspeaker designs

use a combination of passive and active crossover filtering, such as a passive crossover between

the mid- and high-frequency drivers and an active crossover between the low-frequency driver andthe combined mid- and high frequencies.[25][26]

Passive crossovers are commonly installed inside speaker boxes and are by far the most usual type

of crossover for home and low-power use. In car audio systems, passive crossovers may be in aseparate box, necessary to accommodate the size of the components used. Passive crossovers may

be simple for low-order filtering, or complex to allow steep slopes such as 18 or 24 dB per octave.

Passive crossovers can also be designed to compensate for undesired characteristics of driver,

horn, or enclosure resonances,[27] and can be tricky to implement, due to component interaction.Passive crossovers, like the driver units that they feed, have power handling limits, have insertion

losses (10% is often claimed), and change the load seen by the amplifier. The changes are matters

of concern for many in the hi-fi world.[27] When high output levels are required, active crossoversmay be preferable. Active crossovers may be simple circuits that emulate the response of a passive

network, or may be more complex, allowing extensive audio adjustments. Some active crossovers,

usually digital loudspeaker management systems, may include facilities for precise alignment of

phase and time between frequency bands, equalization, and dynamics (compression and limiting)control.[23]

Some hi-fi and professional loudspeaker systems now include an active crossover circuit as part of

an onboard amplifier system. These speaker designs are identifiable by their need for AC power inaddition to a signal cable from a pre-amplifier. This active topology may include driver protection

circuits and other features of a digital loudspeaker management system. Powered speaker systems

are common in computer sound (for a single listener) and, at the other end of the size spectrum, inmodern concert sound systems, where their presence is significant and steadily increasing.

Enclosures

Most loudspeaker systems consist of drivers mounted in an enclosure, or cabinet. The role of the

enclosure is to provide a place to physically mount the drivers, and to prevent sound wavesemanating from the back of a driver from interfering destructively with those from the front; these

typically cause cancellations (e.g., comb filtering) and significantly alter the level and quality of

sound at low frequencies.

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The simplest driver mount is a flat panel (i.e., baffle) with the drivers mounted in holes in it.

However, in this approach, sound frequencies with a wavelength longer than the baffle dimensions

are canceled out, because the antiphase radiation from the rear of the cone interferes with theradiation from the front. With an infinitely large panel, this interference could be entirely

prevented. A sufficiently large sealed box can approach this behavior.[29][30]

Since panels of infinite dimensions are impractical, most enclosures function by containing the rear

radiation from the moving diaphragm. A sealed enclosure prevents transmission of the soundemitted from the rear of the loudspeaker by confining the sound in a rigid and airtight box.

Techniques used to reduce transmission of sound through the walls of the cabinet include thicker

cabinet walls, lossy wall material, internal bracing, curved cabinet wallsor more rarely,visco-elastic materials (e.g., mineral-loaded bitumen) or thin lead sheeting applied to the interior

enclosure walls.

However, a rigid enclosure reflects sound internally, which can then be transmitted back through

the loudspeaker diaphraghmagain resulting in degradation of sound quality. This can be reduced

by internal absorption using absorptive materials (often called "damping"), such as glass wool,wool, or synthetic fiber batting, within the enclosure. The internal shape of the enclosure can also

be designed to reduce this by reflecting sounds away from the loudspeaker diaphragm, where theymay then be absorbed.

Other enclosure types alter the rear sound radiation so it can add constructively to the output from

the front of the cone. Designs that do this (includingbass reflex,passive radiator, transmission

line, etc.) are often used to extend the effective low-frequency response and increase low-frequency output of the driver.

To make the transition between drivers as seamless as possible, system designers have attempted

to time-align (or phase adjust) the drivers by moving one or more driver mounting locationsforward or back so that the acoustic center of each driver is in the same vertical plane. This mayalso involve tilting the face speaker back, providing a separate enclosure mounting for each driver,

or (less commonly) using electronic techniques to achieve the same effect. These attempts have

resulted in some unusual cabinet designs.

The speaker mounting scheme (including cabinets) can also cause diffraction, resulting in peaksand dips in the frequency response. The problem is usually greatest at higher frequencies, where

wavelengths are similar to, or smaller than, cabinet dimensions. The effect can be minimized by

rounding the front edges of the cabinet, curving the cabinet itself, using a smaller or narrowerenclosure, choosing a strategic driver arrangement, using absorptive material around a driver, or

some combination of these and other schemes.

2.4 Specifications

Speaker specifications generally include:

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Speaker or driver type (individual units only) Full-range, woofer, tweeter, ormid-range.

Size of individual drivers. For cone drivers, the quoted size is generally the outside diameter of the

basket.[31] However, it may less commonly also be the diameter of the cone surround, measuredapex to apex, or the distance from the center of one mounting hole to its opposite. Voice-coil

diameter may also be specified. If the loudspeaker has a compression horn driver, the diameter ofthe horn throat may be given.

Rated Power Nominal (or even continuous) power, and peak (or maximum short-term) power aloudspeaker can handle (i.e., maximum input power before destroying the loudspeaker; it is never

the sound output the loudspeaker produces). A driver may be damaged at much less than its rated

power if driven past its mechanical limits at lower frequencies.[32] Tweeters can also be damagedby amplifier clipping (amplifier circuits produce large amounts of energy at high frequencies in

such cases) or by music or sine wave input at high frequencies. Each of these situations might pass

more energy to a tweeter than it can survive without damage. [33] In some jurisdictions, power

handling has a legal meaning allowing comparisons between loudspeakers under consideration.

Elsewhere, the variety of meanings for power handling capacity can be quite confusing.

Impedance typically 4 (ohms), 8 , etc.[34]

Baffle or enclosure type (enclosed systems only) Sealed, bass reflex, etc.

Number of drivers (complete speaker systems only) two-way, three-way, etc.

and optionally:

Crossover frequency(ies) (multi-driver systems only) The nominal frequency boundaries of the

division between drivers.

Frequency response The measured, or specified, output over a specified range of frequencies

for a constant input level varied across those frequencies. It sometimes includes a variance limit,

such as within " 2.5 dB".

Thiele/Small parameters (individual drivers only) these include the driver'sFs (resonance

frequency), Qts (a driver's Q; more or less, its damping factorat resonant frequency), Vas (the

equivalent air compliance volume of the driver), etc.

Sensitivity The sound pressure level produced by a loudspeaker in a non-reverberant

environment, often specified in dB and measured at 1 meter with an input of 1 watt (2.83 rms voltsinto 8 ), typically at one or more specified frequencies. Manufactures often use this rating in

marketing material.

Maximum SPL The highest output the loudspeaker can manage, short of damage or notexceeding a particular distortion level. Manufactures often use this rating in marketing material

commonly without reference to frequency range or distortion level.

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2.5 Electrical characteristics of a dynamic loudspeaker

The load that a driver presents to an amplifier consists of a complex electrical impedanceacombination of resistance and both capacitive and inductive reactance, which combines properties

of the driver, its mechanical motion, the effects of crossover components (if any are in the signal

path between amplifier and driver), and the effects of air loading on the driver as modified by the

enclosure and its environment. Most amplifiers' output specifications are given at a specific powerinto an ideal resistive load; however, a loudspeaker does not have a constant resistance across its

frequency range. Instead, the voice coil is inductive, the driver has mechanical resonances, the

enclosure changes the driver's electrical and mechanical characteristics, and a passive crossoverbetween the drivers and the amplifier contributes its own variations. The result is a load resistance

that varies fairly widely with frequency, and usually a varying phase relationship between voltage

and current as well, also changing with frequency. Some amplifiers can cope with the variationbetter than others can.

To make sound, a loudspeaker is driven by modulated electrical current (produced by an amplifier)

that pass through a "speaker coil" (a coil of copper wire), which then

(through inductance) magnetizes the coil, creating a magnetic field. The electrical currentvariations that pass through the speaker are thus converted to varying magnetic forces, which move

the speaker diaphragm, which thus forces the driver to produce air motion that is similar to the

original signal from the amplifier.

2.6 Electromechanical measurements

Fully characterizing the sound output quality of a loudspeaker driver or system in words is

essentially impossible. Objective measurements provide information about several aspects of

performance so that informed comparisons and improvements can be made, but no combination ofmeasurements summarizes the performance of a loudspeaker system in use, if only because the test

signals used are neither music nor speech. Examples of typical measurements are: amplitude and

phase characteristics vs. frequency; impulse response under one or more conditions (e.g., square

waves, sine wave bursts, etc.); directivity vs. frequency (e.g., horizontally, vertically, spherically,etc.); harmonic and intermodulation distortion vs. SPL output, using any of several test signals;

stored energy (i.e., ringing) at various frequencies; impedance vs. frequency; and small-signal vs.large-signal performance. Most of these measurements require sophisticated and often expensive

equipment to perform, and also good judgment by the operator, but the raw sound pressure level

output is rather easier to report and so is often the only specified valuesometimes inmisleadingly exact terms. The sound pressure level (SPL) a loudspeaker produces is measured

in decibels (dBspl).

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The initial inventor of the speaking trumpet is a subject of historical controversy, as both Samuel

Morland and Athanasius Kircherlay claim to the device. Morland, in a work published in 1671,

wrote about his experimentation with different horns and his most successful variant. This loudesthorn was made of over 20 feet of copper and could supposedly project vocalizations as far as a

mile and a half.

Twenty years earlier, Kircher described a device that could be used for both broadcasting on one

end and overhearing on the other. His coiled horn would be wedged into the side of a building,connecting a speaker or listener inside with the surrounding environment.

Morland favored a straight, tube-shaped speaking device, where an initial sound would reverberate

in waves through the instrument and gradually become louder. Kirchers horn, on the other hand,utilized a cochleate design, where the horn was twisted and coiled, unlike Morlands design.

A later,papier-mache trumpet of special design was the Sengerphone.

The term megaphone was first associated with Thomas Edisons instrument 200 years later. In1878, Edison developed a device similar to the speaking trumpet in hopes of benefiting the deaf

and hard of hearing. His variation included three separate funnels lined up in a row. The two outerfunnels, which were six feet and eight inches long, were made of paper and connected to a tube

inserted in each ear. The middle funnel was similar to Morlands speaking trumpet, but had a

larger slot to insert a users mouth. ]

With Edisons megaphone, a low whisper could be heard a thousand feet away, while a normaltone of voice could be heard roughly two miles away. On the listening end, the receiver could hear

a low whisper at a thousand feet away. The size of the instrument, as one researcher noted, was too

large. George Prescott wrote: The principal drawback at present is the large size of the

apparatus.

3.2 Electric megaphones

In 1954, TOA Corporation developed the EM-202, the world's first electric megaphone.

An electronic megaphone amplifies sound to a higherdecibel level. It can be amplified from over90 dB. It consists of a microphone, an amplifierand a loudspeaker. Common uses for megaphones

are at sporting events,political functions, and generally when one needs to address congregations

of people in open spaces.

A vast array of modern electric megaphones are available to purchase, and characteristics likewattage, weight, price, and the presence of alarms and shoulder straps all contribute to a

consumers choice.

The shape of the megaphone directly affects the range of projection; narrower horns compensate

lower wattage by concentrating sound much sharper than wide horns. Some megaphones even

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include a detachable microphone, so speakers can address a crowd without the instrument

obscuring their face.

3.3 Megaphone use

Besides its practical implications, the megaphone also had a social impact on society. The

megaphone, along with other amplifying technologies like microphones and loudspeakers, helped

promote womens participation in society. In events like the National Republican and Democratic

Conventions of 1920, when the electric megaphone was first becoming popularized, womenutilized these amplifying technologies during roll call of participants.

Portable megaphones are widely used for crowd management and mass communication. When

needing to transmit important information or to guide a large amount of people, an electricmegaphone is valuable if other public announcement devices are not present.

For decades, film directors have used electric megaphones to communicate with their cast and

crew on sets where it was hard to hear. Cecil B. DeMille, director of epic movies like The Ten

Commandments and The King of Kings, was the first director to use a megaphone duringproduction. Many of his films were biblical epics set in vast open spaces that required

communication across hundreds of feet.

In many modern radio ads, producers look to utilize a megaphone effect without actually

recording the instrument. In doing so, they digitize the recognizable characteristics of the electricmegaphone and try to reproduce the qualities of distortion. On recording software

like Logic and Pro Tools, selecting certain filters and settings will produce an artificial sound

almost indistinguishable from an electric megaphone.

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4.1 Modern connectors

Modern TS and TRS connectors are available in three standard sizes. The original 14 in (6.35 mm)version dates from 1878, for use in manual telephone exchanges making it possibly the oldestelectrical connector standard still in use. The 3.5 mm orminiature and 2.5 mm orsub-

miniature sizes were originally designed as two-conductor connectors for earpieces on transistor

radios. The 3.5 mm and 2.5 mm sizes are also referred to as 18 in and332 in respectively in the

United States, though those dimensions are only approximations. All three sizes are now readily

available in two-conductor (unbalanced mono) and three-conductor (balanced mono or

unbalanced stereo) versions.

Four- and five-conductor versions of the 3.5 mm plug are used for certain applications. A four-conductor version is often used in compact camcorders and portable media players, and sometimes

also in laptop computers and smartphones, providing stereo sound plus a video signal. Proprietaryinterfaces using both four- and five-conductor versions exist, where the extra conductors are usedto supply power for accessories. The four-conductor 3.5 mm plug is also used as a speaker-

microphone connector on handheld amateur radio transceivers from Yaesu and on some mobile

phones.

A three- or four-conductor version of the 2.5 mm plug is widely used on cellphonehandsfree headsets, providing mono (three conductor) or stereo (four conductor) sound and

a microphone input. Common stereo headphones with the 2.5 mm plug are often not compatible

with this type of socket. A 3.5 mm version of this plug is now commonly available on mobiletelephones as well. A 3.5 mm stereo-plus-mic jack is available that is compatible with standard

3.5 mm stereo headphones, e.g.Nokia has been widely using TRRS connectors with 3.5 mmdiameter since 2006. The selected pin assignment, with ground on the sleeve, is as well

standardized in OMTP [7] and has been accepted as a national Chinese standard YDT 1885-2009.

TRRS plugs do not work properly with a TRS stereo jack if the ground contact in the jack connects

to the microphone contact on the plug. It is thus a good practice to implement new TRS headphone

jacks using a TRRS mechanical jack and connecting ground to sleeve and the second ring contact.This way such jacks will provide better compatibility with different TRRS cell phone headsets.

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Although relatively unknown in modern consumer electronics, the professional audio world and

the telecommunication industry has used tiny telephone (TT) connectors in patch bays which are

mid-size phone plugs with a 4.40 mm (0.173 in) diameter shaft. In the telecom world, this istermed a "bantam" plug. Though unable to handle as much power and less reliable as a 6.35 mm

(0.250 in) jack,[8]TTs have been used for professional console and

outboardpatchbays in studios and live sound applications, in which one patch panel needs hundredsof patch points in a limited space. The TRS versions of TT connectors are capable of

handlingbalanced line signals and have been employed in pro audio installations. Recently, all-in-

one digital audio switching matrices and digital signal processors have reduced the need forphysical patching and extensive patch bays.

4.2 Mono and stereo compatibility

In the original application in manual telephone exchanges, many different configurations of 6.35

mm (1

4 in) jack plug were used, some accommodating five or more conductors, with several tipprofiles. Of these many varieties, only the two-conductor version with a rounded tip profile was

compatible between different manufacturers, and this was the design that was at first adopted for

use with microphones, electric guitars, headphones, loudspeakers, and many other items of audioequipment.

When a three-conductor version of the 6.35 mm (14 in) jack was introduced for use

with stereo headphones, it was given a sharper tip profile in order to make it possible to

manufacture jacks (sockets) that would accept only stereo plugs, to avoid short-circuiting the rightchannel amplifier. This attempt has long been abandoned, and now the normal convention is that

all plugs fit all sockets of the same size, regardless of whether they are balanced mono, unbalanced

mono or stereo. Most 6.35 mm (1

4 in) plugs, mono or stereo, now have the profile of the originalstereo plug, although a few rounded mono plugs are also still produced. The profiles of stereominiature and subminiature plugs have always been identical to the mono plugs of the same size.

The results of this physical compatibility are:

If a two-conductor plug of the same size is connected to a three-conductor socket, the result is that

the ring (right channel) of the socket is grounded. This property is deliberately used in severalapplications, see "tip ring sleeve", below. However, grounding one channel may also be dangerous

to the equipment if the result is to short circuit the output of the right channel amplifier. In any

case, any signal from the right channel is naturally lost.

If a three-conductor plug is connected to a two-conductor socket, normally the result is to leave thering of the plug unconnected (open circuit). In the days ofvacuum tubes this was also potentially

dangerous to equipment but most solid state devices tolerate this condition well. A 3-conductor

socket could be wired as an unbalanced mono socket to ground the ring in this situation, but themore conventional wiring is to leave the ring unconnected, exactly simulating a mono socket.

4.3 Uses

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Some common uses of jack plugs and their matching sockets are:

Headphone and earphone jacks on a wide range of equipment. 6.35 mm (14 in) plugs are common

on home and professional component equipment, while 3.5 mm plugs are nearly universal forportable audio equipment. 2.5 mm plugs are not as common, but are used on communication

equipment such ascordless phones, mobile phones, and two-way radios.

Consumer electronics devices such as digital cameras, camcorders, and portable DVD players use

3.5 mm connectors for composite video and audio output. Typically, a TRS connection is used formono audio plus video, and a TRRS connection for stereo audio plus video. Cables designed for

this use are often terminated with RCA connectors on the other end.

Hands-free sets and headsets often use 3.5 mm or 2.5 mm connectors. TRS connectors are used for

mono audio out + an unbalanced microphone (with a shared ground). TRRS connectors are used toadd an additional audio-out channel (i.e. stereo out + microphone).

Microphone inputs on tape and cassette recorders, sometimes with remote control switching on thering, on early, monaural cassette recorders mostly a dual-pin version consisting of a 3.5 mm TS for

the microphone and a 2.5 mm TS for remote control which switches the recorder's power supply.

Patching points (insert points) on a wide range of equipment.

Personal computers, sometimes using a sound card plugged into the computer. Stereo 3.5 mm

jacks are used for:

Line in (stereo)

Line out (stereo)

Headphones/loudspeaker out (stereo)

Microphone input (mono, usually with 5 V power available on the ring. Note that traditional,

incompatible, use of a stereo plug for a mono microphone is for balanced output)

Laptop computers generally have one line level jack for headphones and one mono jack for a

microphone at microphone level. You can use an attenuating cable to convert line level or use asignal from an XLR connector, but it is not designed to record from a stereo device such as a radio

or music player.

LCD monitors with built-in speakers will need a 3.5 mm male-male cable from the sound card.

Note: Higher end sound cards sometimes sport a breakout panel which supports 14 in plug

devices as well.

Devices designed for surround output may use multiple jacks for paired channels (ex. TRS for

front left and right; TRRS for front center, rear center, and subwoofer; and TRS for surround left

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and right). Circuitry on the sound device may be used to switch between traditional Line In/Line

Out/Mic functions and surround output.

Electric guitars. Almost all electric guitars use a 14 in mono jack (socket) as their output connector.Some makes (such as Shergold) use a stereo jack instead for stereo output, or a second stereo jack,

in addition to a mono jack (as with Rickenbacker).

Instrument amplifiers for guitars, basses and similar amplified musical instruments.14 in jacks are

overwhelmingly the most common connectors for:

Inputs. A shielded cable with a mono 14 in jack plug on each end is commonly termed aguitarcordor apatching cord, the first name reflecting this usage, the second the history of the jack

plug's development for use in manual telephone exchanges.

Loudspeakeroutputs, especially on low-end equipment. On professional

loudspeakers, Speakon connectors carry higher current, mate with greater contact area, lock in

place and do not short out the amplifier upon insertion or disconnection. However, someprofessional loudspeakers carry both Speakon and TRS connectors for compatibility. Heavy-

duty 14 in loudspeaker jacks are rated at 15 A maximum which limits them to applicationsinvolving less than 1,800 watts. 14 in loudspeaker jacks commonly aren't rigged to lock the plug in

place and will short out the amplifier's output circuitry if connected or disconnected when the

amplifier is live.

Line outputs.

Foot switches and effects pedals. Stereo plugs are used for double switches (for example

by Fender). There is little compatibility between makers.

Effects loops, which are normally wired as patch points.

Electronic keyboards use jacks for a similar range of uses to guitars and amplifiers, and in addition

Sustain pedals.

Expression pedals.

Electronic drums use jacks to connect sensor pads to the synthesizermodule orMIDI encoder. In

this usage, a change in voltage on the wire indicates a drum stroke.

Some compact and/or economy model audio mixing desks use stereo jacks for balanced

microphone inputs.

The majority of professional audio equipment uses mono jacks as the standard unbalanced input oroutput connector, often providing a 14 in unbalanced line connector alongside (or in a few cases in

the middle of!) and as an alternative to an XLRbalanced line connector.

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Modular synthesizers commonly use monophonic cables for creating patches.

4.4 Switch contacts

Panel-mounting jacks are often provided with switch contacts. Most commonly, a mono jack isprovided with one normally closed (NC) contact, which is connected to the tip (live) connection

when no plug is in the socket, and disconnected when a plug is inserted. Stereo sockets commonly

provide two such NC contacts, one for the tip (left channel live) and one for the ring or collar (rightchannel live). Some designs of jack also have such a connection on the sleeve. As this contact is

usually ground, it is not much use for signal switching, but could be used to indicate to electronic

circuitry that the socket was in use.

Less commonly, some jacks are provided with normally open (NO) or change-over contacts,and/or the switch contacts may be isolated from the connector.

The original purpose of these contacts was for switching in telephone exchanges, for which there

were many patterns. Two sets of change-over contacts, isolated from the connector contacts, were

common. The more recent pattern of one NC contact for each signal path, internally attached to theconnector contact, stems from their use as headphone jacks. In many amplifiers and equipment

containing them, such as electronic organs, a headphone jack is provided that disconnects the

loudspeakers when in use. This is done by means of these switch contacts. In other equipment, adummy load is provided when the headphones are not connected. This is also easily provided by

means of these NC contacts.

Other uses for these contacts have been found. One is to interrupt a signal path to enable other

circuitry to be inserted. This is done by using one NC contact of a stereo jack to connect the tip andring together when no plug is inserted. The tip is then made the output, and the ring the input (or

vice versa), thus forming apatch point.

Another use is to provide alternative mono or stereo output facilities on some guitars and

electronic organs. This is achieved by using two mono jacks, one for left channel and one for right,and wiring the NC contact on the right channel jack to the tip of the other, to connect the two

connector tips together when the right channel output is not in use. This then mixes the signals so

that the left channel jack doubles as a mono output.

Where a 3.5 mm or 2.5 mm jack is used as a DC power inlet connector, a switch contact may beused to disconnect an internal battery whenever an external power supply is connected, to prevent

incorrect recharging of the battery.

A standard stereo jack is used on most battery-powered guitareffects pedals to eliminate the needfor a separate power switch. In this configuration, the internal battery has its negative terminal

wired to the sleeve contact of the jack. When the user plugs in a two-conductor (mono) guitar or

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microphone lead, the resulting short-circuit between sleeve and ring connects an internal battery to

the unit's circuitry, ensuring that it powers up or down automatically whenever a signal lead is

inserted or removed. A drawback of this design is the risk of inadvertently discharging the batteryif the lead is not removed after use, such as if the equipment is left plugged in overnight.

Configurations and schematic symbols

These examples are meant to illustrate each possible component of such jacks, but many other

configurations using these basic components are available. All examples in the above figure areoriented so the plug 'enters' from the right.

A. A simple two-conductor jack. The connection to the sleeve is the rectangle towards the right,

and the connection to the tip is the line with the notch. Wiring connections are illustrated as white

circles.

B. A three-conductor, or TRS, jack. The upper connector is the tip, as it is farther away from thesleeve. The sleeve is shown connected directly to the chassis, a very common configuration. This

is the typical configuration for a balanced connection

C. This three-conductor jack has two isolated SPDT switches. They are activated by a plug goinginto the jack, which disconnects one throw and connects the other. The white arrowheads indicate

a mechanical connection, while the black arrowheads indicate an electrical connection. This wouldbe useful for a device that turns on when a plug is inserted, and off otherwise, with the power

routed through the switches.

D. This three-conductor jack has two normally closed switches connected to the contacts

themselves. This would be useful for a patch point, for instance, or for allowing another signal to

feed the line until a plug is inserted. The switches open when a plug is inserted. A common use for

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5.2 Circuit Diagram:

5.3 Parts:

P1 = 22K

R1 = 1M

R2 = 15K

R3 = 470R

R4 = 47K

R5 = 4.7K

R6 = 4.7K

C1 = 100nF-63V

C2 = 100nF-63V

C3 = 10nF-63V

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C4 = 100nF-63V

C5 = 220uF-25V

C6 = 10uF-25V

Q1 = BC547

IC1 = LM 386

J1 = Mono Jack Socket

B1 = 6V Battery

SW1 = SPST Slider Switch

5.4 Procedure of building the bull horn loudspeaker

Step 1: Circuit diagram of the proposed system is designed and finalized.(Refer to Figure 6.1 )

Step 2: All the components to be used are selected which are also mentioned above.

Step 3: All the hardware components are soldered on their respective zero printed circuit boards withthe help of soldering ion, solder and flux according to the hardware schematic shown in the Figure

Step 5: : Testing is done at various levels to finalize the appropriate program for the most properworking of the system

Notes:

Please note that hands-free, uni-directional headset or ear clip microphone types are very

well suited for this device, as also are Clip-on Lavaliere or Lapel microphones.

If a small electrets capsule is used for the microphone, R5, R6 and C6 must be added to the

circuit to provide power supply.

Choose a loudspeaker as large as possible, in order to increase circuit performance.

You can use also two 4 Ohm loudspeakers wired in series or two 8 Ohm types wired in

parallel in order to obtain better results.

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The box containing the amplifier and loudspeaker(s) can be fitted out with a belt and

carried like a shoulder-bag or, if you build a smaller unit, it can be used as a Pick & Go

Belt Clip Speaker.

Chapter -6

FUTURE WORK

If we need to boosts the volume at any public address like at any theatre or concert hall we use

this project. Or if we want to enjoy at own home we use this project as domestic sound

systems.

And this circuit can be implemented as a chain in any hi-fi stereo sound system an also used asan instrument amplifiers include guitar amplifiers.

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REFERENCES

1. http://www.eleccircuit.com

2. http://www.circuitstoday.com

3. www.technologystudent.com

4. http://en.wikipedia.org

5. http://www.bcae1.com
http://www.eleccircuit.com/http://www.circuitstoday.com/http://www.technologystudent.com/http://en.wikipedia.org/http://www.bcae1.com/http://www.eleccircuit.com/http://www.circuitstoday.com/http://www.technologystudent.com/http://en.wikipedia.org/http://www.bcae1.com/

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