25-03-2011, 04:04 PM
PRESENTED BY
T.SIVAPRIYA
G.SUJITHA
V.SATHYAS.
NANDHINI
[attachment=11007]
HIGH FREQUENCY AMPLIFIER
Objective
To amplify the low frequency sound through the high sensitivity microphone.
To provide a very clear voice of any soft and unpleasant sound using condenser microphone.
R6-C4 network is used to RF-decouple positive-supply pin 6 and R8-C7 is an optional Zobel network that ensures high frequency stability when feeding an inductiveheadphone load.
Capacitor C6 (22μF, 16V) wired between pin 7 and ground gives additional ripple rejection. The output of LM386N power amplifier can safely drive a standard 32-ohm monophonic headphone/earphone.
Microphone
Condenser means capacitor, an electronic component which stores energy in the form of an electrostatic field. The term condenser is actually obsolete but has stuck as the name for this type of microphone, which uses a capacitor to convert acoustical energy into electrical energy.
Condenser microphones require power from a battery or external source. The resulting audio signal is stronger signal than that from a dynamic. Condensers also tend to be more sensitive and responsive than dynamics, making them well-suited to capturing subtle nuances in a sound. They are not ideal for high-volume work, as their sensitivity makes them prone to distort.
Working of microphone
A capacitor has two plates with a voltage between them. In the condenser mic, one of these plates is made of very light material and acts as the diaphragm
The diaphragm vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. Specifically, when the plates are closer toget capacitance increases and a charge current occurs
When the plates are further apart, capacitance decreases and a discharge current occurs. A voltage is required across the capacitor for this to work. This voltage is supplied either by a battery in the mic or by external .
LM386N operation
The gain is 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. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.
Advantages
LM386N is a complete battery operation.
circuit is simple and easy to construct.
circuit is portable . consumes very small quisient current
LM386N is available in 8 pin MSOP package.
It amplifies sound upto 50 decibels and can be used as spy instrument.
T.SIVAPRIYA
G.SUJITHA
V.SATHYAS.
NANDHINI
[attachment=11007]
HIGH FREQUENCY AMPLIFIER
Objective
To amplify the low frequency sound through the high sensitivity microphone.
To provide a very clear voice of any soft and unpleasant sound using condenser microphone.
R6-C4 network is used to RF-decouple positive-supply pin 6 and R8-C7 is an optional Zobel network that ensures high frequency stability when feeding an inductiveheadphone load.
Capacitor C6 (22μF, 16V) wired between pin 7 and ground gives additional ripple rejection. The output of LM386N power amplifier can safely drive a standard 32-ohm monophonic headphone/earphone.
Microphone
Condenser means capacitor, an electronic component which stores energy in the form of an electrostatic field. The term condenser is actually obsolete but has stuck as the name for this type of microphone, which uses a capacitor to convert acoustical energy into electrical energy.
Condenser microphones require power from a battery or external source. The resulting audio signal is stronger signal than that from a dynamic. Condensers also tend to be more sensitive and responsive than dynamics, making them well-suited to capturing subtle nuances in a sound. They are not ideal for high-volume work, as their sensitivity makes them prone to distort.
Working of microphone
A capacitor has two plates with a voltage between them. In the condenser mic, one of these plates is made of very light material and acts as the diaphragm
The diaphragm vibrates when struck by sound waves, changing the distance between the two plates and therefore changing the capacitance. Specifically, when the plates are closer toget capacitance increases and a charge current occurs
When the plates are further apart, capacitance decreases and a discharge current occurs. A voltage is required across the capacitor for this to work. This voltage is supplied either by a battery in the mic or by external .
LM386N operation
The gain is 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. The quiescent power drain is only 24 milliwatts when operating from a 6 volt supply, making the LM386 ideal for battery operation.
Advantages
LM386N is a complete battery operation.
circuit is simple and easy to construct.
circuit is portable . consumes very small quisient current
LM386N is available in 8 pin MSOP package.
It amplifies sound upto 50 decibels and can be used as spy instrument.