Chapter 1

THE PROBLEM AND ITS BACKGROUND

Introduction

Educating is a challenging, yet a rewarding profession. Instructors play a

vital role in helping individuals to acquire and develop the knowledge and skills

that the students need. Education allows each individual to ascertain each

capability in pursuing self-development and skills advancement for future use in

the good of many and for the development of the society. In the process of

learning and teaching, communication within a classroom is one of the effective

techniques in working relationship between educators and learners. Discussions

provide opportunity for the students to interact with each other and share unique

perspectives, which can deepen learning and knowledge in the learning process.

Within a traditional classroom environment the instructor has an ability to

discuss using his/her normal vocal assertion. Effective communication during

these discussions requires the instructor to guide the process, ensuring that

learners maintain respect and professionalism with their responses. The process

of focused good communication also involves guiding students beyond their

initial reactions and personal belief systems, utilizing higher-order thinking and

promoting cognitive development.

Through positive communication with the instructor and other learners in

the class, are likely to find an environment that is conducive to learning and the

2

knowledge creation process. When an instructor is successful in facilitating

effective communication during class discussions the learners begin to feel a

sense of collaboration and through a mutual exchange of information they are

more likely to share their ideas, knowledge, beliefs, and experiences.

Nowadays, the discussion is not limited to the typical scenario that the

teacher will discuss everything and the students will be listening. The students

are being encouraged to do oral presentations and reporting for them to improve

their oral communication skills as well. Their ability to share to others what they

know could be very essential as they work afterwards. Thus, the sound system

will also help them as they make their audio-visual presentations.

In this day and age, new technology and innovations would always pique

the interest of the people, especially if it would make their lives more comfortable,

stress-free, and hassle-free. With that statement in mind, the proponents put

forward a project that would solve teachers lecturing woes. It would use the

capabilities of sound systems and incorporate it into the classroom, thereby

alleviating professors voices as well as giving the students the clarity needed to

understand the lecture.

Instructional materials are educational resources used to improve

students knowledge, abilities, and skills, to monitor their assimilation of

information, and to contribute to their total development and upbringing.

There are three basic types of instructional materials: concrete objects,

including objects from the world of nature; representations of concrete objects

3

and phenomena; and description of such objects and phenomena by means of

the signs, words, and sentences of natural and artificial languages. Another type

of instructional materials is technological instructional media. Among these are

equipment for the transmission and assimilation of information recorded on film

or on phonograph recordings: film project, tape recorders, phonographs, and

television sets.

Technological instructional media is being commonly used at present time,

and is still taking large advancements on providing convenience to both the

instructor and students. Different technologies booming up are designed with the

purpose of enhancing the traditional procedures on how teachers could educate

their students the best way that they can.

An example of the technological instructional material is a sound amplifier

system which will enable the professor to speak normally to theirs students

without having to maximize their voice as they consider whether the students

could hear what they have been discussing. Thus, the proponents will ponder on

the improvement of this project.

Every stereo system requires an amplifier its what breathes life into the

loudspeakers. Even the smallest loudspeakers have an amplification module

somewhere in their structure; only its usually integrated so well that it cant be

seen. Mobile phones, for instance, have amplifiers for their in-built speakers. In

addition, most entry level speakers are what are known as active speakers. That

4

means they come with integrated amplification. PC and multimedia speakers, for

instance, are usually active.

Those who are looking to graduate from smaller speakers with integrated

amplification to proper hi-fi systems will need to cross one obstacle: the stereo or

hi-fi amplifier. This may at first seem intimidating or like an unnecessary expense,

yet for truly hi-fi sound, theres simply no substitute for a separate hi-fi amplifier

connected to proper stereo speakers.

The group will create a sound amplifier system that will be used in the

classroom MB107-A. Two high quality speakers and a wireless lavalier

microphone will be installed in the system.

Objectives Of The Study

The general objective of this project is to create a convenient way for the

students of MB107-A to hear the lessons clearly from the scheduled instructor

using a sound amplifier system and a lavalier microphone or lapel as a

transmitter. Specifically, the study aims to attain the following:

1. Determination of components including:

1.1. Material selection

1.2. Component specifications

1.3. Availability

1.4. Cost

2. Construct the schematic diagram of the circuit

3. Assembly of the project

4. Fabrication of the project

5

5. Test the effectiveness of the project

Operational Framework

This division presents the step by step procedures on how the researchers

will conduct the study. Furthermore, this division presents the process of

acquiring knowledge on creating a sound system and the production it will

undergoes.

Ideally, the team of this project aims to create an efficient sound amplifier

that will use a Lapel as the transmitter.

Figure 1 shows the operational framework.

6

Figure 1. Operational Framework

USER

MICROPHONE

DVD PLAYER PORTABLE GADGETS

AMPLIFIER

POWER SUPPLY

SPEAKER 1

SPEAKER 2

7

Figure 1 shows the operation of the sound system. Initially, users will

transmit data on the amplifier by electric signal through the use of microphones.

A power supply is then connected to the system to power the amplifier. The

voltage supply for the amplifier is 12V. The amplifier then will process the input

signal (microphone) and will output it through the speakers. Also, a DVD player is

included in the system. A USB port is provided for other portable gadgets like

flash drives. All inputs of the amplifier will be processed and will be outputted in

the speakers.

Importance Of The Study In the project sound amplifier system, importance of the study is cited in

the succeeding aspects:

To De La Salle Lipa (DLSL), this will serve as an improvement of the

classroom MB107-A.

To the instructors, this will aid them in facilitating the discussion.

To the Electrical Engineering students of DLSL, this project will help them

in hearing the lecture more clearly and introduce new applications in Electrical

Engineering.

To the researchers, the project will serve as a theoretical and practical

application of their learning on Industrial Electronics.

To the future researchers, this could be their research background

for their study.

8

Scope And Limitations

The project will be concerning the installation of sound reinforcement

system that will serve as an effective facility. Design layouts of the room will be

observed. Assortment of suitable resources and determination of materials will

also be included in the project. Flowcharts will be designed, so that there will be

an aid on using the amplifier as well as its integration.

The project will be limited to the room MB107-A since the amplifier will be

used for classroom purposes only. The lapel will be utilized by the spokesperson

and the amplifiers will encompass the entire classroom area.

Limitations were considered in the study. The system will not be limited to

voice amplification. Sound files that could be used for audio-visual presentations

may also be amplified through the sound system. The project is designed to be

used in an educational setting, but can also be adapted by different industries.

Also, the lapel and the DVD player cant be used at the same time. Video

projectors are not also included in the study.

Definition Of Terms

For better understanding of the study, the following terms are defined.

AC to DC converter. A circuit or device that changes DC voltage to AC

voltage.

Audio. A sound, especially when recorded, transmitted, or reproduced.

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Amplifier. An electronic device for increasing the amplitude of electrical

signals, used chiefly in sound reproduction.

Bandwidth. The range of frequencies within a given band, in particular that

used for transmitting a signal.

Beam. A transmitted radio signal or broadcast in a specified direction.

Capacitor. A device used to store an electric charge, consisting of one or

more pairs of conductors separated by an insulator.

Frequency. The rate at which a vibration occurs that constitutes a wave,

either in a material or in an electromagnetic field, usually measured per second.

Fuse. A part of the circuit which consists of conductor which melts easily

and breaks the connection when current exceeds the predetermined value.

Gain. Measure of the ability of a two port circuit to increase the power or

amplitude of a signal from the input to the output port by adding energy

converted from some power supply to the signal.

Generator. A dynamo or similar machine for converting mechanical energy

into electricity.

Impedance. The effective resistance of an electric circuit or component to

alternating current, arising from the combined effects of ohmic resistance and

reactance.

Microphone. An instrument for converting sound waves into electrical

energy variations, which may then be amplified, transmitted, or recorded.

10

PCB. Mechanically supports and electrically connects electronic

components using conductive tracks, pads and other features etched from

copper sheets laminated onto a non-conductive substrate.

Peak. Reach a highest point, either of a specified value or at a specified

time.

Power supply. An electronic device that supplies electric energy to an

electrical load.

Rectifier. An electrical device that converts an alternating current into a

direct one by allowing a current to flow through it in one direction only.

Resistor. A device having a designed resistance to the passage of an

electric current.

Speaker. An electrical device used to make sound or music louder.

Terminal. A point of connection for closing an electric circuit.

Transformer. An apparatus for reducing or increasing the voltage of an

alternating current.

Ultrasonic. Of, concerned with, or producing waves with the same nature

as sound waves but frequencies above audio frequencies.

Vacuum tube. An electron tube containing a near-vacuum that allows the

free passage of electric current.

Waveform. A curve showing the shape of a wave at a given time.

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Wireless microphone. A microphone without a physical cable connecting it

directly to the sound recording or amplifying equipment with which it is

associated.

Woofer. A loudspeaker driver designed to produce low frequency sounds,

typically from around 40 hertz up to about a kilohertz or higher.

12

Chapter 2

REVIEW OF RELATED LITERATURE

This chapter shows the related literature and studies which serve as basis

for the researchers conduct of the study.

Review Of Related Literature

This division presents the ideas and concepts about an amplifier. The

materials and components of the project will be thoroughly discussed to help the

researchers in the conduct of the study.

Amplifier

Figure 2 shows an example of an amplifier.

Figure 2. Amplifier

http://live.coffeeweb.in/

Amplifier, in electronics, device that responds to a small input signal

(voltage, current, or power) and delivers a larger output signal that

13

contains the essential waveform features of the input signal. Amplifiers of

various types are widely used in such electronic equipment as radio and

television receivers, high-fidelity audio equipment, and computers.

Amplifying action can be provided by electromechanical devices

(e.g., transformers and generators) and vacuum tubes, but most electronic

systems now employ solid-state microcircuits as amplifiers. Such an

integrated circuit consists of many thousands of transistors and related

devices on a single tiny silicon chip.

A single amplifier is usually insufficient to raise the output to the

desired level. In such cases the output of the first amplifier is fed into

a second, whose output is fed to a third, and so on, until the output level is

satisfactory. The result is cascade, or multistage amplification. Long-

distance telephone, radio, television, electronic control and measuring

instruments, radar, and countless other devices all depend on this basic

process of amplification. The overall amplification of a multistage amplifier

is the product of the gains of the individual stages.

(http://www.britannica.com)

If the input current is simply a brief pulse of electricity designed to

switch something on or off, you can use an electromagnetic relay to

amplify it. A relay uses electromagnets to couple two electric circuits

together so that when a small current flows through one of the circuits, a

much larger current flows through the other. Using a relay, a tiny electric

http://www.britannica.com/EBchecked/topic/531340/secondhttp://www.explainthatstuff.com/howrelayswork.html

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current can power something that would normally need a much larger

current to operate it. For example, it might have a photoelectric cell set up

to receive a beam of invisible infrared light in an intruder alarm. When

someone breaks the beam, a tiny current is sent to a relay that snaps into

action and turns on a much larger current that rings the alarm bell on the

side of a house. The tiny output current from a photoelectric cell would be

far too small to power a bell all by itself.

An amplifier is basically an AC-to-DC power converter. It takes ac

power from the wall outlet (at fixed frequency and voltage) and converts it

to audio power at the loudspeaker terminals (with variable frequency and

voltage). The audio output is supposed to be a faithful replica of the line-

level audio input, only larger.

First we need a power supply. This subsystem accepts the ac

power from the wall, isolates the audio circuitry from shock hazard, raises

or lowers the ac voltage to suit the needs of the amplifier power rating,

converts the ac power to dc, and stores it in an energy reservoir.

The other major subsystem is the output section. This is the

electronic circuitry that accepts the line level audio input and uses this

information to control high-power transistors. These convert the energy

contained in the dc reservoir to a high-power audio waveform that is a

magnified replica of the input signal

http://www.explainthatstuff.com/how-photoelectric-cells-work.htmlhttp://www.explainthatstuff.com/electromagnetic-spectrum.htmlhttp://www.explainthatstuff.com/intruderalarms.html

15

Audio power amplifiers are used to receive the amplified input from

a series of voltage For the circuitry to operate, the pre-amplifier, the DC

power supply is used to convert AC voltage to DC voltage which is use to

operate devices. Amplifiers, and then provide sufficient power to drive

loudspeakers. The 220-V line voltage is reduced to a lower AC voltage

value with the use of a 12-0-12 step-down transformer. The 12-0 terminals

of the transformer are used to produce a 12 V AC voltage. This voltage is

then fed to the rectifier circuit which converts the AC signal to pulsating DC

signal.

The second stage of the pre-amplifier circuit is in common-emitter

configuration. The input signal from the first stage is now applied across the

base terminal and ground of the circuit while the output signal is read across

collector terminal with respect to the ground of the circuit. Good impedance

matching is observed as the common-base configurations high output

impedance matches the common-emitter configurations high input

impedance. The second stage possesses high voltage gain when the

emitter resistor is bypassed, which is necessary for the amplifiers purpose.

However, the voltage gain would gradually decrease its stability. The output

of the second stage is then fed as the input signal to the power amplifier.

The power amplifier is a circuit which subjects the pre-amplified

signal to higher amplification. The power amplifier amplifies the audio

16

signals in the range of human hearing to higher signals which will drive the

speakers with higher power ratings.

The microphone serves as the input transducer which converts

human voice to AC electrical signals. Human voice converted to electrical

signals has a typical value of 2mV. This signal is fed to the pre-amplifier

circuit. The pre-amplifier circuit consists of two stages: a common base

configuration followed by a common-emitter configuration. The common

base configuration is first used to serve the purpose of impedance

matching, so that the microphones low output impedance matches the input

impedance of the pre-amplifier circuit.

All amplifiers have a maximum power limit. The voltage at the

amplifier output can only go as high as the voltage in the dc power supply.

If the signal tries to exceed this limit, and the waveform becomes flattened.

This problem, called clipping because it looks like the top of the waveform

has been clipped off, results in the familiar sound of an overdriven amplifier.

Increasing the supply voltage adds cost and weight to the amplifier, so

amplifier power has a big effect on price.

Amplifiers have a minimum rated output impedance, which should

be equal or less than the impedance of the loudspeaker load. As the

impedance of the loudspeaker gets lower, more current will be drawn from

the amplifier. This is why, up to a point, the amplifier power rating increases

into lower impedances. However, the increased current puts a greater

17

strain on the amplifier components and the power supply. At some minimum

impedance, the strain will get so high that the power-supply voltage sags or

the transistors overheat. Any further decrease in impedance will cause the

amplifier circuitry to collapse, resulting in less power, or it could even cause

amplifier failure.

Amplifiers also must reproduce all audio frequencies, from the

highest to the lowest, at equal volume. This ability is called flat frequency

response because the graph of amplifier gain vs. frequency is a flat line.

If the gain at low frequencies falls off, the sound will be thin or lacking

in impact. If the high frequency gain rolls off, the sound will be dull or

muffled. Most modern direct-coupled amplifiers are capable of very flat

response, but sometimes the frequency response is intentionally limited to

protect the loudspeakers from excessive power at frequencies we cant

hear.

Intermediate frequency amplifier

Figure 3 shows an intermediate frequency amplifier.

Figure 3. Intermediate frequency amplifier

http://en.wikipedia.org

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Intermediate Frequency amplifiers are tuned amplifiers used

in radio, TV and radar. Their purpose is to provide the majority of the

voltage amplification of a radio, TV or radar signal, before the audio

or video information carried by the signal is separated (demodulated)

from the radio signal. They operate at a frequency lower than that of

the received radio signal, but higher than the audio or video signals

eventually produced by the system. The frequency at which I.F.

amplifiers operate and the bandwidth of the amplifier depends on the

type of equipment. For example, in AM radio receivers the I.F.

amplifiers operate at around 470 kHz and their bandwidth is normally

10 kHz (465 kHz to 475 kHz), while TV commonly uses 6 MHz

bandwidth for the I.F. signal at around 30 to 40MHz, and in radar a

band width of 10 MHz may be used.

Radio frequency amplifier

Figure 4 shows a radio frequency amplifier.

Figure 4. Radio frequency amplifier

http://en.wikipedia.org/wiki/

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Radio Frequency amplifiers are tuned amplifiers in which the

frequency of operation is governed by a tuned circuit. This circuit may

or may not, be adjustable depending on the purpose of the amplifier.

Bandwidth also depends on use and may be relatively wide, or

narrow. Input resistance is generally low, as is gain. A special feature

of RF amplifiers where they are used in the earliest stages of a

receiver is low noise performance. It is important that background

noise generally produced by any electronic device, is kept to a

minimum because the amplifier will be handling very low amplitude

signals from the antenna (V or smaller). For this reason it is

common to see low noise FET transistors used in these stages.

Ultrasonic frequency amplifier

Figure 5 shows an ultrasonic frequency amplifier.

Figure 5. Ultrasonic frequency amplifier

http://www.techzonics.com

Ultrasonic amplifiers are a type of audio amplifier handling

frequencies from around 20 kHz up to about 100 kHz; they are

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usually designed for specific purposes such as ultrasonic cleaning,

metal fatigue detection, ultrasound scanning, remote control systems

etc. Each type will operate over a fairly narrow band of frequencies

within the ultrasonic range.

Wideband amplifiers must have a constant gain from DC to

several tens of MHz. They are used in measuring equipment such as

oscilloscopes etc. where there is a need to accurately measure

signals over a wide range of frequencies. Because of their extremely

wide bandwidth, gain is low.

DC amplifier

Figure 6 shows a DC amplifier.

Figure 6. DC amplifier

http://3.bp.blogspot.com

DC amplifiers are used to amplify DC (0Hz) voltages or very

low frequency signals where the DC level of the signal is important.

They are common in many electrical control systems and

measuring instruments.

http://www.learnabout-electronics.org/ac_theory/ac_waves02.php#dclevel

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Video amplifier

Figure 7 shows a video amplifier.

Figure 7. Video amplifier

http://www.cop-usa.com

Video amplifiers are a special type of wide band amplifier that

also preserve the DC level of the signal and are used specifically for

signals that are to be applied to CRTs or other video equipment. The

video signal carries all the picture information in TV, video and radar

systems. The bandwidth of video amplifiers depends on use. In TV

receivers it extends from 0Hz (DC) to 6MHz and is wider still in radar.

In physics, number of waves that pass a fixed point in unit

time; also the number of cycles or vibrations undergone during one

unit of time by a body in periodic motion. A body in periodic motion

is said to have undergone one cycle or one vibration after passing

through a series of events or positions and returning to its original

state.

http://www.britannica.com/EBchecked/topic/596034/timehttp://www.britannica.com/EBchecked/topic/451920/periodic-motionhttp://www.britannica.com/EBchecked/topic/451920/periodic-motionhttp://www.britannica.com/EBchecked/topic/627269/vibration

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Amplifier gain and bandwidth

Figure 8 shows amplifier gain and bandwidth.

Figure 8. Amplifier gain and bandwidth

http://www.learnabout-electronics.org

If the period, or time interval, required to complete one cycle

or vibration is 1/2second, the frequency is 2 per second; if the

period is 1/100 of an hour, the frequency is 100 per hour. In

general, the frequency is the reciprocal of the period, or time

intervali.e., frequency = 1/period = 1/(time interval).

The gain of an amplifier is the ratio of the output signal to the

input signal. There are three categories of gain: voltage gain (Av),

current gain (Ai) and power gain (Ap). Any amplifier has a value for

all three gains.

The bandwidth (BW) of an amplifier is the range of

frequencies, from lowest to highest, over which the amplifier

delivers sufficient gain. The meaning of "sufficient" depends on your

application, but one common meaning is when the gain (20 Log Av)

http://www.britannica.com/EBchecked/topic/451868/periodhttp://www.britannica.com/EBchecked/topic/531340/second

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has dropped by 3dB. IC amplifiers of the "op-amp" variety

(operational amplifiers) will work from DC up to some frequency,

the "break-point", where gain has dropped by 3dB. Amplifiers which

amplify DC as well as AC are said to be "direct-coupled".

There are two important things to see on the graph. First is

the "break-point" which occurs at the "break-frequency" fB. Av is

constant until the break-point. The second thing is that after fB, Av

starts to "roll off" at a constant rate of 20 dB per decade. The point

where the graph crosses through the horizontal axis is the GBW. A

roll-off of 20dB / dec is typical of many amplifiers. So high-gain

amplifiers in general, and op-amps in particular, use "negative

feedback" to reduce the gain to a usable level. A total discussion of

negative feedback is beyond the scope of this article. We will just

say that negative feedback takes some of the output signal and

connects it back to the input in such a way that the signal fed back

subtracts from the input. The effect is to cause the amplifier to

operate at a lower value of gain while the GBW stays the same.

With no feedback, the amplifier is said to be "open-loop". With

negative feedback, it is said to be "closed-loop".

One of the most important metrics for a power amplifier is its

power efficiency. It is a measure of how well a device converts one

energy source to another. In RF circuit design, power amplifier

24

efficiency is calculated in three ways with wide acceptance. The

first one is drain efficiency, usually denoted as D. Drain efficiency

does not take input power into account. If the gain is high, it is safe

to ignore the effect of input power. However, in RF power

amplifiers, the input power can sometime be substantial, therefore

measures that include the effect of input power are necessary.

Power added efficiency (PAE), denoted as PAE, is the most

common used measure which takes input power into account. It is

calculated as the ratio of the difference between output power

POUT and input power PIN to DC power consumed from supply.

If the gain is high, PAE approaches drain efficiency. In a

chain of cascaded amplifiers, if each amplifier has the same PAE,

then the PAE of the entire chain will be exactly the same as the

PAE of an individual amplifier. A less frequently used measure is

called drain efficiency gets its name from FET devices, though it

probably should be called collector efficiency when BJT devices are

used. Total efficiency, it is calculated as the ratio of output power

POUT to the sum of input power PIN and DC power consumed

from supply.

In fact, total efficiency is the measure that makes the most

sense from a thermodynamic point of view. This can be seen by

noting that the total dissipated power is simply a function of the

25

output power POUT and total efficiency TOTAL. This measure

can be used to evaluate the effectiveness of an amplifier and

estimate heat removal requirements. Nonetheless, PAE is still the

most popular measure in industry. One point that should be noted

here is that all three measures mentioned above are for

instantaneous efficiency.

Conventional power amplifier designs give maximum

efficiency only at a single power level, usually near the maximum

rated power for the amplifier. As the output power is backed off

from that single point, the efficiency typically drops rapidly.

However, back-off situation is inevitable in todays wireless

communication. First, the need to conserve battery power and to

mitigate interference to other users necessitates the transmission of

power levels well below the peak output power. Transmitters will

only use peak output power when necessary. Second, the

requirement for both high data rate and efficient utilization of the

increasingly crowded spectrum necessitates the use of both

amplitude and phase modulation schemes. In a number of

applications, it is more convenient and robust to use a large

number of carriers with low data rates than a single carrier with a

high data rate. For example, orthogonal frequency division

multiplexing (OFDM) employs multiple carriers with the same

26

amplitude modulation, separated in frequency and codes so that

the modulation products from one carrier are zero at the other

carriers in an ideal system. The resultant composite signal has a

peak-to-average ratio in the range of 12~17-dB.

Obviously, high instantaneous efficiency at peak output level

is certainly desirable. However, what more important is the

average efficiency. Or in other words, power amplifiers need to

maintain high efficiency over a wide dynamic range. Therefore,

average efficiency is a useful measure. Average drain efficiency,

denoted as , is calculated as the ratio of average output power

OUTPUT P to the average DC power from supply.

The PDF of the transmitted power depends on various

factors, such as the distance to the base-station, multi-path,

attenuation by surroundings and antenna orientation. In urban

environment, output power levels of transmissions are usually

between 10~20-dB back off from the peak value. In suburban

environment, peak output power is needed in some scenarios.

However, same as in urban environment, output power is usually

between 10~20-dB back-off from peak output. And it is quite

obvious that if the PA is operated in back-off, average efficiency is

reduced even more.

27

PCB

Figure 9 shows an actual printed circuit board or PCB.

Figure 9. Printed circuit board

http://ecx.images-amazon.com

PCBs are resistant to acids and bases as well as to heat, they have

been used as an insulating material in electric equipment, such as

transformers and capacitors, and also in heat transfer fluids and in

lubricants. PCBs have also been used in wide range of products such as

plasticizers, surface coatings, inks, adhesives, flame-retardants, paints,

and carbonless duplicating paper.

Two different systems are used for naming PCBs. In the IUPAC

system used in the examples above, the numbers at the beginning of the

name specify the sites where chlorines are attached to the phenyl rings.

Another system assigns a separate number, from 1 to 209, to each of the

209 specific PCB congeners.

http://www.greenfacts.org/glossary/pqrs/pcbs-polychlorinated-biphenyls.htmhttp://www.greenfacts.org/glossary/pqrs/ph.htmhttp://www.greenfacts.org/glossary/pqrs/ph.htmhttp://www.greenfacts.org/glossary/def/electric-transformer.htmhttp://www.greenfacts.org/glossary/abc/capacitor.htmhttp://www.greenfacts.org/glossary/ghi/heat-transfer-fluid.htmhttp://www.greenfacts.org/glossary/jkl/lubricant.htmhttp://www.greenfacts.org/glossary/pqrs/plasticiser.htmhttp://www.greenfacts.org/glossary/def/flame-retardant.htmhttp://www.greenfacts.org/glossary/pqrs/pcbs-polychlorinated-biphenyls.htmhttp://www.greenfacts.org/glossary/ghi/iupac.htmhttp://www.greenfacts.org/glossary/pqrs/phenyl-ring.htmhttp://www.greenfacts.org/glossary/pqrs/pcbs-polychlorinated-biphenyls.htmhttp://www.greenfacts.org/glossary/abc/congener.htm

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Generally, PCBs are not very soluble in water, but readily soluble in

fats. This solubility in fat explains why PCBs can build up in animal fat and

along the food chain. The degree of solubility is largely dependent on the

number and position of chlorine grains in the PCBmolecule.

(www.greenfacts.org)

Speakers

Figure 10 shows an example of a speaker.

Figure 10. Speakers

http://i.kinja-img.com/

Computer speakers, or multimedia speakers, are speakers external

to a computer, which disable the lower fidelity built-in speaker. They often

have a low-power internal amplifier. The standard audio connection is a

3.5 mm (approximately 1/8 inch) stereo phone connector often color-

coded lime green (following the PC 99 standard) for computer sound

cards. A few use a RCA connector for input. There are also USBspeakers

which arepowered from the 5 volts at 500 milliamps provided by the USB

port, allowing about 2.5 watts of output power. Computer speakers were

http://www.greenfacts.org/glossary/pqrs/soluble-solubility.htmhttp://www.greenfacts.org/glossary/abc/chlorine.htmhttp://www.greenfacts.org/glossary/pqrs/pcbs-polychlorinated-biphenyls.htmhttp://www.greenfacts.org/glossary/pqrs/pcbs-polychlorinated-biphenyls.htmhttp://en.wikipedia.org/wiki/Loudspeakerhttp://en.wikipedia.org/wiki/Phone_connector_%28audio%29http://en.wikipedia.org/wiki/PC_System_Design_Guide#PC_99http://en.wikipedia.org/wiki/Sound_cardhttp://en.wikipedia.org/wiki/Sound_cardhttp://en.wikipedia.org/wiki/RCA_connectorhttp://en.wikipedia.org/wiki/Universal_Serial_Bushttp://en.wikipedia.org/wiki/Volt

29

introduced by Altec Lansing in 1990. The internal amplifiers require an

external power source, usually an AC adapter. More sophisticated

computer speakers can have a subwoofer unit, to enhance bass output,

and these units usually include the power amplifiers both for the bass

speaker, and the small satellite speakers. (www.alteclansing.com)

Power supply

Figure 11 shows a power supply.

Figure 11. Power supply

http://www.patartambunan.com

Short for Power Supply and sometimes abbreviated as PSU, which

is short for Power Supply Unit. The PS is an internal hardware component

used to supply the components in a computer with power by converting

potentially lethal 110-115 or 220-230 volt alternating current (AC) into a

steady low-voltage direct current (DC) usable by the computer. A power

supply is rated by the number of watts it generates. In addition to the

power cord connection the back also has a fan opening to draw air out of

http://en.wikipedia.org/wiki/Altec_Lansinghttp://en.wikipedia.org/wiki/AC_adapterhttp://www.computerhope.com/jargon/c/computer.htmhttp://www.computerhope.com/jargon/a/ac.htmhttp://www.computerhope.com/jargon/d/dc.htm

30

the power supply, a small red switch to change the power supply voltage,

and the rocker switch to turn the power supply on and off.

(www.computerhope.com)

Microphone

Figure 12 represent a microphone.

Figure 12. Microphone

http://www.nav.co.uk/

A lavaliere microphone or lavaliere (also known as a lav, lapel mic,

clip mic or personal mic) is a small electret or dynamic microphone used

for television, theatre, and public speaking applications, in order to allow

hands-free operation. They are most commonly provided with small clips

for attaching to collars, ties, or other clothing. The cord may be hidden by

clothes and either run to a radio frequency transmitter kept in a pocket or

clipped to a belt, or routed directly to the mixer or a recording device.

(http://books.google.com.)

Resistor

Figure 13 shows a resistor.

http://www.computerhope.com/jargon/r/rocker-switch.htmhttp://en.wikipedia.org/wiki/Electret_microphonehttp://en.wikipedia.org/wiki/Microphone#Dynamic_microphonehttp://en.wikipedia.org/wiki/Radio_frequencyhttp://books.google.com.ph/books?id=e35kJYAlyCgC&pg=PA22&redir_esc=y#v=onepage&q&f=false

31

Figure 13. Resistor

Resistors, (R) are the most fundamental and commonly used of all

the electronic components, to the point where they are almost taken for

granted. There are many different Types of Resistor available for the

electronics constructor to choose from, from very small surface mount chip

resistors up to large wire wound power resistors.

Fuse

Figure 14 shows an actual representation of a fuse.

Figure 14. Fuse

Source: www.google.com

32

In electronics and electrical engineering, a fuse is a type of low

resistance resistor that acts as a sacrificial device to

provide overcurrent protection, of either the load or source circuit. Its

essential component is a metal wire or strip that melts when too much

current flows through it, interrupting the circuit that it connects. Short

circuits, overloading, mismatched loads, or device failure are the prime

reasons for excessive current. Fuses are an alternative to circuit breakers.

Integrated circuits

Figure 15 shows an example of an integrated circuit.

Figure 15. Integrated circuits

.

http://www.nteinc.com

An integrated circuit, or IC, is small chip that can function as an

amplifier, oscillator, timer, microprocessor, or even computer memory. An

IC is a small wafer, usually made of silicon, that can hold anywhere from

hundreds to millions of transistors, resistors, and capacitors. These

extremely small electronics can perform calculations and store data using

either digital or analog technology. (www.techterms.com)

http://en.wikipedia.org/wiki/Electronicshttp://en.wikipedia.org/wiki/Electrical_engineeringhttp://en.wikipedia.org/wiki/Resistorhttp://en.wikipedia.org/wiki/Sacrificial_devicehttp://en.wikipedia.org/wiki/Overcurrenthttp://en.wikipedia.org/wiki/Electrical_networkhttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Short_circuithttp://en.wikipedia.org/wiki/Circuit_breakerhttp://techterms.com/definition/digitalhttp://techterms.com/definition/analog

33

Capacitor

Figure 16 shows a capacitor.

Figure 16. Capacitor

Capacitors are components that are used to store an electrical

charge and are used in timer circuits. A capacitor may be used with a

resistor to produce a timer. Sometimes capacitors are used to smooth a

current in a circuit as they can prevent false triggering of other

components such as relays. When power is supplied to a circuit that

includes a capacitor - the capacitor charges up. When power is turned off

the capacitor discharges its electrical charge slowly.

Woofer

Figure 17 shows a woofer.

Source: www.google.com

34

Figure 17. Woofer .

http://cdn.falconacoustics.co.uk

Woofer is the term commonly used for

a loudspeaker driver designed to produce low frequency sounds, typically

from around 40 hertz up to about a kilohertz or higher. The most common

design for a woofer is the electrodynamic driver, which typically uses a stiff

paper cone, driven by a voice coilwhich is surrounded by a magnetic field.

The voice coil is attached by adhesives to the back of the speaker cone.

The voice coil and magnet form a linear electric motor. When current flows

through the voice coil, the coil moves in relation to the frame according

to Fleming's left hand rule, causing the coil to push or pull on the driver

cone in a piston-like way. The resulting motion of the cone creates sound

waves as it moves in and out. (www.hypertextbook.com)

http://en.wikipedia.org/wiki/Loudspeakerhttp://en.wikipedia.org/wiki/Speaker_driverhttp://en.wikipedia.org/wiki/Low_frequencyhttp://en.wikipedia.org/wiki/Hertzhttp://en.wikipedia.org/wiki/Voice_coilhttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Electric_motorhttp://en.wikipedia.org/wiki/Fleming%27s_left_hand_rule

35

Review Of Related Studies

Different published and unpublished studies were taken into account to

further understand the concept a sound system.

According to Edwall (2008) Designing a low-noise amplifier using

traditional methods is an involved process that requires a solid understanding if

underlying principles. Low Noise amplifiers are key components in the receiving

end of nearly every communications system. The wanted input signal of these

systems is usually very weak and the primary purpose of the LNA is

consequently to amplify the signal; while at the same time adding as little

additional noise as possible. Its performance is measured in a number of figures

of merit, among which gain and noise figure are most notable while dynamic

range, return loss and stability are examples of others.

From Liu (2006), efficiency is one of the most important metrics in the

design of power amplifiers conventional designs give maximum efficiency only at

a single power level, usually near the maximum rated power for the amplifier. As

the output power is backed off from that single point, the efficiency drops rapidly.

However, power back-off is inevitable in todays wireless communication system.

Todays consumers demand wireless systems that are low-cost, power efficient,

reliable and have a small form-factor. High levels of integration are desired to

reduce cost and achieve compact form factor for high volume applications.

36

Hence the long term vision or goal for wireless transceivers is to merge as many

components as possible, if not all, to a single die in an expensive technology.

From the discussion of Sun et al. (2011) the audio power amplifier is

designed with three parts: pre-amplifier unit, tonality control unit and power

amplifier unit. For the pre-amplifier unit, Tl071CP integrated operational amplifier

is used to achieve the gain of 4; for the tonality control unit, a filter is designed to

achieve different tone; for the power amplifier unit, LM386N-1 integrated low

voltage power amplifier is applied. With tonality control, different sound can be

heard by ear clearly.

Justification Of The Study

The study of Edwall et. al., considered the construction of designing a low-

noise amplifier which is found to be similar with the study conducted by the

proponents. While at the same time it also allows adding a little noise as possible.

The components and methodology used in their study where in tradition and

follows the basic principles of an amplifier which the proponents had also

conducted in their project study.

Similarly is the study conducted by Liu et. al., considered the efficiency of

the amplifier on its conventional designs. The study of the proponents differ by not

using the power back-off method of having the output because in today, wireless

communication system does not apply to it.

37

The study conducted by Sun et. al., which is the audio power amplifier is

also beneficial to the proponents having their study connected with the pre-

amplifier unit, tonality control and power amplifier unit. The study on focused on

the application of tonality control as it provides better voice and hearing quality as

well as the use of power amplifier unit which is the main focus of the study.

38

Chapter 3

RESEARCH METHOD AND PROCEDURES

This chapter discusses how the proponents will conduct the study. It is

also the procedural method that the proponents will pursue in order to design and

develop the computer software for layouts of residential pole construction.

Research Design/Method

In conducting the study, the proponents will use engineering planning,

analysis and design type of research. This method includes: preliminary design

stage, design stage, development stage and testing stage.

Stages In The Design Development

Pre-design Stage

The researchers have gathered numerous references and related

literature. The researchers also conducted consultations and asked for

advices from instructors and senior students from Electrical Engineering

Department with regards to theories and programming. The gathered

information will serve as stepping stones of the researchers in doing the

proposed study.

39

Design Stage

The gathered information from the preliminary stage will be applied

in this stage. Substantial preparations are needed in developing a

program such as developing flowcharts, pseudo code and algorithms.

Factors including programming language and its accuracy will be taken

into consideration to create a functional program. It is imperative that the

researchers have the proper skills and knowledge in programming for this

matter.

Development Stage

In this stage, the researchers will apply the programming

techniques and information gathered in creating the source code of the

proposed program. The researchers must make sure that the program is

free of errors and/or bugs to ensure its functionality.

Testing Stage

The researchers will test the functionality, accuracy and

effectiveness of the program in this stage. Multiple trials will be done to

test the correctness of the study and debug all the errors in the codes.

Other adjustments may be applied in this stage if necessary. The

researchers will conduct the User Acceptance Test (UAT) for the study to

be evaluated by the users. The researchers will assess the evaluation,

and will be considered in improving the program.

40

Chapter 4

ANALYSIS, PRESENTATION AND INTERPRETATION

This chapter presents the design requirements, project cost, assembly

and the actual testing and evaluation of the sound system.

Determination Of The Design Requirements And Considerations

This section represents the requirements and considerations in creating

the design and development of a 15 watt sound system for MB 107 - A.

Design requirements and considerations

In this section, the determination of the project design plan and

suitable materials and specifications of the instruments that are needed for

the project is determined.

Project plan

This section shows the layout of the components of the

project and schematic diagrams.

Room layout

See Appendix A.

Speaker layout

See Appendix A.

Amplifier layout

See Appendix A.

41

Case layout

See Appendix A.

Block diagram

Figure 18 shows the block diagram of the power supply used

in the project.

Figure 18. Power supply block diagram

Figure 18 shows the block diagram of the power supply used in the

project. In order to operate the system, the amplifier and stereo are

powered by a DC power supply/ The DC power supply is used to convert

AC voltage to DC voltage which is used to operate the system. The 220-V

line voltage is reduced to a lower AC voltage value with the use of a 12-0-

12 step down transformer. The 12-0-12 terminals of the transformer are

used to produce a 12 V AC voltage. A was then used to convert the AC

signal to pulsating DC signal. The pulsating DC signal was then fed to a

filter to smoothened resulting to a steady DC voltage. Finally, using a

regulator which secures a 12-V output DC voltage from the power supply.

This 12-V DC voltage operates the whole system.

INPUT Transformer Rectifier Filter Regulator OUTPUT

42

Figure 19 shows the block diagram of the sound system.

Figure 19. Block diagram of the sound system

Figure 19 shows the block diagram of the sound system. A 12V

power supply is used to power the whole sound system. Microphones,

DVD players and other portable gadgets such as flash disks were used as

inputs to the power amplifier. The microphones serves as the input

transducer which convert human voice to AC electrical signals. Two

43

speakers were connected to the power amplifier to serve as an output

producing sound.

Determination of suitable materials and specifications

Through the circuit diagram, the researchers were able to

determine the major components that are needed for the project

specifically the power supply, amplifier, speakers and other

components.

For the enclosure of the amplifier and DVD player, the group

used scrap woods then covered it with a black cloth cover.

Specifications of the materials needed

This section discussed the different specifications of the

materials that are used in the project.

Power supply

Figure 20 shows the power supply used in the sound

system.

Figure 20. Power supply

44

The image shows the power supply used in the

system. A 12-0-12 V step down transformer was used for the

power supply.

Amplifier

Figure 21 shows the amplifier of the sound system.

Figure 21. Amplifier

The image shows the amplifier used in the sound

system.

Microphone

Figure 22 shows the microphone.

Figure 22. Microphone

45

The image shows the microphone used in the system

which converts human voice into AC electrical signal.

Speaker

Figure 23 shows the speaker used in the sound

system.

Figure 23. Speaker

Two speakers was used for the sound system.

DVD player

Figure 24 shows the DVD player used in the sound

system.

Figure 24. DVD player

46

A DVD player was used for the system. A USB slot was also

provided.

Determination Of The Cost Construction Of The Project

This section details the determination of the construction cost of the

project and components used in the sound system.

Bill of materials and specifications

In order to determine the total cost of the project, the bill of

materials that is used in the project is represented.

Table 1. Bill of materials and specifications

See Appendix B.

Fabrication And Assembly

This section provides the details about the physical construction of the

casing.

Assembly

This section shows the process of installing and assembly of the

sound system.

Components assembly

Figure 25 shows the components for the sound system.

47

Figure 25. Components

The image shows the components for the sound system

composed of a speaker, power supply and an amplifier.

Raceway installation

Figure 26 shows the installation of the raceway for the sound

system.

Figure 26. Raceway installation

48

The image shows the installation of the raceway for the

sound system.

Drilling

Figure 27 shows the drilling process for the speakers.

Figure 27. Drilling

The image shows the drilling process for the installation of

the speakers.

Final assembly

Figure 28 shows the final assembly of the casing for the DVD and

amplifier.

49

Figure 28. Final assembly

The image shows the finished assembly of the system.

Evaluation Of The Project Through Actual Testing

This section presents the actual testing done by the group in order to

check the effectivity and efficiency of the sound system.

Different tests were conducted upon installation of the sound system.

First, the testing of the speakers. In order for the group to determine the speaker,

a flash drive was inserted to an USB slot in the DVD player. The desired output

was obtained. The speaker sounded smoothly. Next, testing of the microphones.

The microphone used in the sound system has a receiver. The microphone fed

the receiver through electrical signals. The desired output was also obtained

50

during the tests. Finally, the DVD player and microphones. In order for the group

to determine the functionality of the sound system, the group had then checked

whether the DVD player and microphone will work in unison. From the tests

conducted, it was found out that the DVD player and microphone can only

worked individually. Using both components was not applicable.

Testing

1. Testing the speakers.

2. Testing of the microphones.

3. Testing of the DVD player and microphones.

51

Chapter 5

SUMMARY OF FINDINGS, CONCLUSION AND RECOMMENDATION

This chapter presents the summary of findings based from the testing that

had been made by the proponents, the conclusions that had been drawn based

from the objective of the project and the recommendations for further

improvements and development of the study.

Summary Of Findings The research study as a whole, involves a number of works to determine

the parameters and obtain the functionality of the design. The following

statements were the findings obtained after the design and development of a 15-

watt sound system for MB 107-A:

1. The project plan includes the design layout, schematic diagram of the

trainer, the schematic diagrams of the operational framework,

speakers block diagram, and amplifiers block diagram. Proper

selections of materials are considered in order to develop a 15-watts

sound system.

2. In developing the 15-watt sound system, the proponents chose the

best materials that were suitable for amplifying the sound. The total

cost of the materials is P 6,500.

52

3. The placement of the speakers is indeed a big factor which can affect

the output of the system. For auditory reasons, the speakers were

placed at the back of the classroom.

4. The fabrication and assembly of the speaker configuration was done

with the help of skilled persons to ensure the safety of the people using

it. The fabrication of the enclosure was done through many processes

such as cutting, punching, assembling, and lastly, painting of the case

of the speakers. The assembly was also done step by step such as the

attachment and positioning of the components based on the design.

5. In order to determine the loudness and functionality of the trainer, the

proponents conducted series of experiments.

Conclusions

Based from the study that has been made, the following conclusions are

drawn:

1. The speaker configuration, the speakers itself, and the functionality of

the lapel microphone are great factors in order to achieve the desired

output value of the system.

2. Engineering procedures and proper measurements are implemented

that results to a good construction, fabrication and assembly of the

trainer.

53

The developed 15-watt sound system can help in amplifying

professors voice while not compromising on the sound quality.

Through actual testing, the functionality of the sound system is proven.

Recommendations

Based from the above findings and conclusions, the proponents present

the following recommendations:

1. Future proponents who will work on the same study can place an extra

pair of speakers at the upper corners of the room, provided that those

speakers would only serve as a supplement to the main speakers at

the back, therefore having a lower wattage.

2.

3. Further studies can be made for more improvements of the sound

system such as adding components of Industrial Electronics.