Chapter 6 - Audio Amplifier

7/29/2019 Chapter 6 - Audio Amplifier

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ap erap eru ou o

AmplifierAmplifier


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that amplifies low-power audio signals

between 20 - 20 000 Hz, the human range

loudspeakers and is the final stage in a

.


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Consist of :-

y Pre-Amplifiers

y Tone Control Networks

y Driver Amplifiers

y Power Amplifier


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Block Diagram FunctionBlock Diagram Function

y Input transducer

y Microphone - a transducer which converts sound to

e ectr ca s gna .

y Amplifies the small audio signal (voltage) from the

microphone.

y Tone Control amplifier :

Adjust the nature of the audio signal. The tone controladjusts the balance of high and low frequencies. The volume

Normally has few button such as volume, bass, treble anecho.


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y Driver amplifier :

y Strengthen the signal received from the tone

control circuit

y Power Amplifier :

Amplify the signal from the driver amplifier to

a suitable value, so that it can drive the.

y pea er A transducer which convert the electrical


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Pre-amplifier Tone Control Amplifier Power Amplifier


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y There are 4 t e of Power Am lifier

circuit :- Sin le ended

Push pull

Com lementar s mmetr

Integrated circuit


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Sin le Ended Circuit

Q1

a


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y

Transistor Q1 open/short no sound/ nopower supply.

y Capacitor C1 open/ short no input signal

y Resistor Ra open/short no sound/ no powersupp y


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Push Pull Circuit

R1

R2


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y Transistor TR1 atau TR2 :

pintas-keluaran bererutan amplitud rintangan R1 & R2terbakar.

er u a- ereru an amp u

y an :

pintas/terbuka tiada suara

y Perintang pincang :

-


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Possible Faults in ComplementaryPossible Faults in Complementary

ymme ryymme ry


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Complementary Symmetry

y Transistor keluaran: Sekali imbas kita perhatikantransistor-transistor keluaran di sambung terus dari bekalanmelalui rintan an-rintan an rendah dan ke bumi. ika di beripincang ,transistor berfungsi penuh iaitu mengalirkan arusmaksimum.Ini membebankan transistor keluaran.Oleh itu

kerosakan yang paling kerap berlaku ialah pada transistor.

y Keadaan kerosakan, boleh terbuka atau terpintas.Setengah-

sambungan bekalan ke transistor keluaran.Jika salah satutransistor keluran terpintas atau terbuka ,keluaran menjadibererutan atau tidak berfungsi langsung.


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y Public address or PA system is a combination of a set of audio

.

y Often used in schools and office buildings, PA systems can be used

for announcements or emergency information and provide a simple

way to get information out quickly.


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y P.A S stem can be divided b two

parts which is

Low Level System


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y Basic PA systems are consist of :-

Loudspeakers

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Chapter 6 - Audio Amplifier