Introduction: PUBLIC ADDRESSED SYSTEM
THIS PROJECT IS CONSISTING OF TWO INDIVIDUAL CIRCIUTS. THE 1ST ONE IS MICROPHONE PRE AMPLIFIER AND THE 2ND ONE IS STERIO POWER AMPLIFIER. BOTH CIRCIUTS ARE COUPLED BY DIRECT COULING METHOD.
BLOCK DIAGRAMOF P-A SYSTEM
“DIFFRENCE BETWEEN PREAMPLIFIER AND AMPLIFIER”
A PREAMPLIFIER CANNOT AMPLIFIY, AND HAS NO SPEAKER CONNECTION WHILE AN AMPLIFIER CANNOT BE PROCESS T SOURCE METARIAL, AND CANNOT BE CONNECTED TO SOURCE DEVICE. A PREAPLIFIER IS USELESS WITHOUT AN AMPLIFIER.
A microphone preamplifier is a sound engineering device that prepares a microphone signal to be processed by other equipment. Microphone signals are normally too weak to be transmitted to units such as mixing consoles and recording devices.Preamplifiers increase a microphone signal to line-level (i.e. the level of signal strength required by such devices) by providing stable gain while preventing induced noise that would otherwise distort the signal.
The term "power amplifier" is a relative term with respect to the amount of power delivered to the load and/or sourced by the supply circuit. In general a power amplifier is designated as the last amplifier in a transmission chain (the output stage) and is the amplifier stage that typically requires most attention to power efficiency. Efficiency considerations lead to various classes of power amplifier: see power amplifier classes.
THIS PROJECT HAVE TWO AMPLIFIER CKTS WHICH ARE CONNECTED BY DIRECT COUPLING METHOD.A PREAMPLIFIER IS USE FOR MICROPHONE. INPUT IS GIVEN TO MICROPHONE AND THE OUTPUT WILL BE TAKEN BY LOUDSPEAKER. WE CAN SAY THAT MIC IS A INPUT TRANSDUSER AND LOUDSPEAKER IS A OUTPUT TRRANSDUSER. MIC IS CONNECTED AT THE INPUT SIDE OF THE PREAMPLIFIER AND THE SPEAKER IS CONNECTED AT THE OUTPUT SIDE OF POWER AMPLIFIER.
THE VCC OF PREAMPLIFIER IS 9-12VOLT AND THE VCC OF POWER AMPLIFIER IS 48VOLTS.AT THE INPUT SIDE MICROPHONE CONVERTS ACOUSTICAL SIGNAL INTO ELECTRICAL SIGNAL AND THE SIGNAL IS RUN FROM PREAMPLIFIER TO POWER AMPLIFIER. THE POWER AMPLIFIER AMPLIES THE INPUT SIGNALS IN TERMS OF VOLTAGE AND CURRENT. THEN THE AMPLIFIED SIGNAL IS REACHES AT OUTPUT TRANSDUCER CALLED SPEAKER.
SUPPLY VOLTAGE (POWER AMPLIFIER) = 24,24VOLTS
SUPPLY VOLTAGE (PREAMPLIFIER) = 9-12VOLTS
INPUT OF POWER AMPLIFIER = 0.8VOLTS
OUTPUT OF POWER AMPLIFIEER = 60VOLTS
TOTAL GAIN = 75
AMPARES OF CKT = 2AMP