Download - 60 Seconds Voice Recording and Playback Device

7/28/2019 60 Seconds Voice Recording and Playback Device

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CHAPTER: 1

INTRODUCTION

The APR9600 device offers true single-chip voice recording, non-volatile storage, and

playback capability for 40 to 60 seconds. The device supports both random and sequential access of

multiple messages. Sample rates are user-selectable, allowing designers to customize their design for

unique quality and storage time needs. Integrated output amplifier, microphone amplifier, and AGC

circuits greatly simplify system design. The device is ideal for use in portable voice recorders, toys, and

many other consumer and industrial applications. APLUS integrated achieves these high levels of storage

capability by using its proprietary analog/multilevel storage technology implemented in an advanced Flash

non-volatile memory process, where each memory cell can store 256 voltage levels. This technology

enables the APR9600 device to reproduce voice signals in their natural form. It eliminates the need for

encoding and compression, which often introduce distortion.

BHARATH COLLEGE OF ENGINEERING & TECHNOLOGY FOR WOMEN

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CHAPTER: 2

2.1 LIST OF COMPONENTS

1. Diodes

IN4007 4 No

2. Resistors

4.7k 2No

1.2k 1No220k 1No

100k 2No

1k 1No

68k 1No

0.56k 2No

3. Capacitors

0.1F 5No

0.04 F 1No

4. Transistors

7805 1No

5. LEDS

Red 1No

White 1No

6. Filters

1000F 1No

220F 1No

22F 1No


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2.2F 1No

4.7F 1No

10F 1No

100F 1No

47f 1No

7. IC

LM386 1No

APR9600 1No

8. Slide on-off switch 1No

9. Preset Resistor 10k 1No

10. Battery 9v

11. Push button 6No

12. Mike 1No

13. Speaker 1No (4-16, 10w)

2.2 DESCRIPTION OF COMPONENTS:

1. DIODE

In electronics, a diode is a type of two-terminalelectronic component with a nonlinearcurrent

voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of

semiconductor material connected to two electrical terminals. A vacuum tube diode (now rarely used

except in some high-power technologies) is a vacuum tube with two electrodes: aplate and acathode.

The most common function of a diode is to allow an

electric current to pass in one direction (called the diode's

forward direction), while blocking current in the opposite

direction (the reverse direction). Thus, the diode can be

thought of as an electronic version of a check valve. This

unidirectional behavior is called rectification, and is used to convert alternating current to direct current

and to extract modulation from radio signals in radio receivers.


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However, diodes can have more complicated behavior than this simple onoff action

Semiconductor diodes do not begin conducting electricity until a certain threshold voltage is present in the

forward direction (a state in which the diode is said to be forward biased). The voltage drop across a

forward biased diode varies only a little with the current, and is a function of temperature; this effect can

be used as a temperature sensor or voltage reference.

Semiconductor diodes have nonlinear electrical characteristics, which can be tailored by

varying the construction of theirPN junction. These are exploited in special purpose diodes that perform

many different functions. For example, diodes are used to regulate voltage (Zener diodes), to protect

circuits from high voltage surges (Avalanche diodes), to electronically tune radio and TV receivers

(varactor diodes), to generate radio frequency (oscillationstunnel diodes, Gunn diodes, IMPATT diodes)

and to produce light (light emitting diodes). Tunnel diodes exhibit negative resistance, which makes them

useful in some types of circuits.

Diodes were the first semiconductor electronic devices. The discovery of crystals' rectifying

abilities was made by German physicist Ferdinand Braun in 1874. The first semiconductor diodes, called

cat's whisker diodes, developed around 1906, were made of mineral crystals such as galena. Today most

diodes are made ofsilicon, but othersemiconductorssuch as germanium are sometimes used.

A modern semiconductor diode is made of a crystal of semiconductor like silicon that has

impurities added to it to create a region on one side that contains negative charge carriers (electrons)

calledn-type semiconductor, and a region on the other side that contains positive charge carriers (holes)

called p-type semiconductor. The diode's terminals are attached to each of these regions. The boundary

within the crystal between these two regions, called a PN junction, is where the action of the diode takes

place. The crystal conducts a current of electrons in a direction from the N-type side (called the cathode)

to the P-type side (called the anode), but not in the opposite direction. However, conventional current

flows from anode to cathode in the direction of the arrow (opposite to the electron flow, since electrons

have negative charge).

Another type of semiconductor diode, the Schottky diode, is formed from the contact between

a metal and a semiconductor rather than by a pn junction.

Currentvoltage characteristic


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A semiconductor diodes behavior in a circuit is given by its currentvoltage characteristic, or

IV graph (see graph below). The shape of the curve is determined by the transport of charge carriers

through the so-called depletion layerordepletion regionthat exists at thepn junction between differing

semiconductors. When a pn junction is first created, conduction-band (mobile) electrons from the N-

doped region diffuse into the P-doped region where there is a large population of holes (vacant places for

electrons) with which the electrons "recombine". When a mobile electron recombines with a hole, both

hole and electron vanish, leaving behind an immobile positively charged donor (dopant) on the N side and

negatively charged acceptor (dopant) on the P side. The region around the pn junction becomes depleted

ofcharge carriers and thus behaves as an insulator.

However, the width of the depletion region (called the depletion width) cannot grow without

limit. For each electronhole pairthat recombines, a positively charged dopant ion is left behind in the N-

doped region, and a negatively charged dopant ion is left behind in the P-doped region. As recombination

proceeds more ions are created, an increasing electric field develops through the depletion zone which acts

to slow and then finally stop recombination. At this point, there is a "built-in" potential across the

depletion zone.

If an external voltage is placed across the diode with the same polarity as the built-in potential,

the depletion zone continues to act as an insulator, preventing any significant electric current flow (unless

electron/hole pairs are actively being created in the junction by, for instance, light. seephotodiode). This

is the reverse bias phenomenon. However, if the polarity of the external voltage opposes the built-in

potential, recombination can once again proceed, resulting in substantial electric current through the pn

junction (i.e. substantial numbers of electrons and holes recombine at the junction). For silicon diodes, the

built-in potential is approximately 0.7 V (0.3 V for Germanium and 0.2 V for Schottky). Thus, if an

external current is passed through the diode, about 0.7 V will be developed across the diode such that the

P-doped region is positive with respect to the N-doped region and the diode is said to be "turned on" as it

has a forward bias.

A diodes 'IV characteristic' can be approximated by four regions of operation.


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At very large reverse bias, beyond the peak inverse voltage or PIV, a process called reverse

breakdownoccurs which causes a large increase in current (i.e. a large number of electrons and holes are

created at, and move away from the pn junction) that usually damages the device permanently. The

avalanche diode is deliberately designed for use in the avalanche region. In the zener diode, the concept of

PIV is not applicable. A zener diode contains a heavily doped pn junction allowing electrons to tunnel

from the valence band of the p-type material to the conduction band of the n-type material, such that the

reverse voltage is "clamped" to a known value (called the zenervoltage), and avalanche does not occur

Both devices, however, do have a limit to the maximum current and power in the clamped reverse-voltage

region. Also, following the end of forward conduction in any diode, there is reverse current for a short

time. The device does not attain its full blocking capability until the reverse current ceases.

The second region, at reverse biases more positive than the PIV, has only a very small reverse

saturation current. In the reverse bias region for a normal PN rectifier diode, the current through the

device is very low (in the A range). However, this is temperature dependent, and at sufficiently hightemperatures, a substantial amount of reverse current can be observed (mA or more).

The third region is forward but small bias, where only a small forward current is conducted.

As the potential difference is increased above an arbitrarily defined "cut-in voltage" or "on-

voltage" or "diode forward voltage drop (Vd)", the diode current becomes appreciable (the level of current

considered "appreciable" and the value of cut-in voltage depends on the application), and the diode

presents a very low resistance. The currentvoltage curve is exponential. In a normal silicon diode at rated

currents, the arbitrary cut-in voltage is defined as 0.6 to 0.7 volts. The value is different for other diode

types Schottky diodescan be rated as low as 0.2 V, Germanium diodes 0.25 to 0.3 V, and red or blue

light-emitting diodes(LEDs) can have values of 1.4 V and 4.0 V respectively.


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At higher currents the forward voltage drop of the diode increases. A drop of 1 V to 1.5 V is typical at full

rated current for power diodes.

2.RESISTOR:

Resistor is a two-terminal, linear, passive electronic component that implements electrica

resistance as a circuit element. Resistance is the property of a component which restricts the flow of

electric current. Energy is used up as the voltage across the component drives the current through it and

this energy appears as heat in the component.

Resistance is measured in ohms, the symbol for ohm is an

omega.

The behavior of an ideal resistor is dictated by the relationship specified

by Ohm's law:

Ohm's law states that the voltage (V) across a resistor is proportional to

the current (I), where the constant of proportionality is the resistance (R).

Equivalently, Ohm's law can be stated:

This formulation states that the current (I) is proportional to the voltage (V) and inversely proportional to

the resistance (R).

Function:

Resistors restrict the flow of electric current, for example a resistor is placed in series with light-

emitting diode(LED0 to limit the flow current passing through the LED.

1 is quite small so resistor values are often gives in K and M .

Resistor values are normally shown using coloured bands.


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Each colour represents a number as shown in the table:

Tabel:1

Most resistors have 4 bands:

The first band gives the first digit.

The second band gives the second digit.

The third band indicates the number of zeros.


COLOUR NUMBER

BLACK 0

BROWN 1

RED 2

ORANGE 3

YELLOW 4

GREEN 5

BLUE 6

VIOLET 7

GRAY 8

8


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The fourth band is used to shows the tolerance of the resistor.

Resistors connected in series:

In a series configuration, the current through all of the resistors is the same, but the voltage

across each resistor will be in proportion to its resistance. The potential difference (voltage) seen across

the network is the sum of those voltages, thus the total resistance can be found as the sum of those

resistances:

As a special case, the resistance of N resistors connected in series, each of the same resistance

R, is given by NR.

Resistors connected in parallel:

Resistors in aparallel configuration are each subject to the same potential difference (voltage)

however the currents through them add. The conductances of the resistors then add to determine the

conductance of the network. Thus the equivalent resistance (Req) of the network can be computed:

The parallel equivalent resistance can be represented in equations by two vertical lines "||" (as

in geometry) as a simplified notation. For the case of two resistors in parallel, this can be calculated using:

.

Combination of series and parallel resistors:

As a special case, the resistance of N resistors connected in parallel, each of the same

resistance R, is given by R/N.

A resistor network that is a combination of parallel and series connections can be broken up into smaller

parts that are either one or the other. For instance,


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.

Power dissipation:

The power P dissipated by a resistor (or the equivalent resistance of a resistor network) is

calculated as:

.

3.CAPACITOR

Just like the resistor, the capacitor, sometimes referred to as a condenser, is a passive device

and one which stores its energy in the form of an electrostatic field producing a potential difference (Static

Voltage) across its plates. In its basic form a capacitor consists of two or more parallel conductive (metal)

plates that do not touch or are connected but are electrically separated either by air or by some form of

insulating material such as paper, mica or ceramic called the dielectric. The conductive plates of a

capacitor can be square, circular or rectangular, or be of a cylindrical or spherical shape with the shapeand construction of a parallel plate capacitor depending on its application and voltage rating.

When used in a direct-current or DC circuit, a capacitor blocks the flow of current through it, but when

it is connected to an alternating-current or AC circuit, the current appears to pass straight through it with

little or no resistance. If a DC voltage is applied to the capacitors

conductive plates, a current flow charging up the plates with

electrons giving one plate a positive charge and the other plate an

equal and opposite negative charge. This flow of electrons to the

plates is known as the Charging Current and continues to flow

until the voltage across both plates (and hence the capacitor) is


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equal to the applied voltage VC. At this point the capacitor is said to be fully charged with electrons with

the strength of this charging current at its maximum when the plates are fully discharged and slowly

reduces in value to zero as the plates charge up to a potential difference equal to the applied supply

voltage and this is illustrated below.

Capacitor Construction

The parallel plate capacitor is the simplest form of capacitor and its capacitance value is fixed

by the surface area of the conductive plates and the distance or separation between them. Altering any two

of these values alters the value of its capacitance and this forms the basis of operation of the variable

capacitors. Also, because capacitors store the energy of the electrons in the form of an electrical charge on

the plates the larger the plates and/or smaller their separation the greater will be the charge that the

capacitor holds for any given voltage across its plates. In other words, larger plates, smaller distance,

more capacitance.

By applying a voltage to a capacitor and measuring the charge on the plates, the ratio of the

charge Q to the voltage V will give the capacitance value of the capacitor and is therefore given as: C =

Q/V this equation can also be re-arranged to give the more familiar formula for the quantity of charge on

the plates as: Q = C x V

Although we have said that the charge is stored on the plates of a capacitor, it is more correct

to say that the energy within the charge is stored in an "electrostatic field" between the two plates. When

an electric current flows into the capacitor, charging it up, the electrostatic field becomes stronger as it

stores more energy. Likewise, as the current flows out of the capacitor, discharging it, the potential


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difference between the two plates decreases and the electrostatic field decreases as the energy moves out

of the plates.

The property of a capacitor to store charge on its plates in the form of an electrostatic field is

called the capacitance of the capacitor. Not only that, but capacitance is also the property of a capacitor

which resists the change of voltage across it.

The Capacitance of a Capacitor

The unit of capacitance is the farad (abbreviated to F) named after the British physicist Michael

Faraday and is defined as a capacitor has the capacitance ofOne farad when a charge ofone coulomb is

stored on the plates by a voltage ofOne volt. Capacitance, C is always positive and has no negative units.

However, the Farad is a very large unit of measurement to use on its own so sub-multiples of the Farad are

generally used such as micro-farads, nano-farads and pico-farads, for example.

Units of Capacitance

Micro farad (F) 1F = 1/1,000,000 = 0.000001 = 10-6 F

Nano farad (nF) 1nF = 1/1,000,000,000 = 0.000000001 = 10-9 F

Pico farad (pF) 1pF = 1/1,000,000,000,000 = 0.000000000001 = 10-12 F

The capacitance of a parallel plate capacitor is proportional to the

area, A of the plates and inversely proportional to their distance or separation, d (i.e. the dielectric

thickness) giving us a value for capacitance ofC = k( A/d ) where in a vacuum the value of the constant k

is 8.84 x 10-12 F/m or 1/4..9 x 109, which is the Permittivity of free space. Generally, the conductive

plates of a capacitor are separated by air or some kind of insulating material or gel rather than the vacuum

of free space.

The Dielectric of a Capacitor


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As well as the overall size of the conductive plates and their distance or spacing apart from

each other, another factor which affects the overall capacitance of the device is the type of dielectric

material being used. In other words the "Permittivity" ( ) of the dielectric. The conductive plates are

generally made of a metal foil or a metal film but the dielectric material is an insulator. The various

insulating materials used as the dielectric in a capacitor differ in their ability to block or pass an electrical

charge. This dielectric material can be made from a number of insulating materials or combinations of

these materials with the most common types used being: air, paper, polyester, polypropylene, Mylar,

ceramic, glass, oil, or a variety of other materials.

The factor by which the dielectric material, or insulator, increases the capacitance of the

capacitor compared to air is known as the dielectric constant, k and a dielectric material with a high

dielectric constant is a better insulator than a dielectric material with a lower dielectric constant. Dielectricconstant is a dimensionless quantity since it is relative to free space. The actual permittivity or "complex

permittivity" of the dielectric material between the plates is then the product of the permittivity of free

space (o) and the relative permittivity (r) of the material being used as the

dielectric and is given as:

Complex Permittivity

As the permittivity of free space, o is equal to one, the value of the complex permittivity will

always be equal to the relative permittivity. Typical units of dielectric permittivity, or dielectric constant

for common materials are: Pure Vacuum = 1.0000, Air = 1.0005, Paper = 2.5 to 3.5, Glass = 3 to 10, Mica

= 5 to 7, Wood = 3 to 8 and Metal Oxide Powders = 6 to 20 etc.

This then gives us a final equation for the capacitance of a capacitor as:


13


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One method used to increase the overall capacitance of a capacitor is to "interleave" more plates

together within a single capacitor body. Instead of just one set of parallel plates, a capacitor can have

many individual plates connected together thereby increasing the area, A of the plate.

4.VOLTAGE REGULATOR

7805 is a voltage regulator integrated circuit. It is a member of 78XX series of fixed linear

voltage regulator ICs .The voltage source in a circuit may have fluctuations and would not give the fixed

voltage output .the voltage regulator IC maintains the output voltage at a constant value. the XX in 78XX

indicates the fixed output voltage it is designed to provide.7805 provides +5V regulator power supply.

capacitors of suitable values can be connected at input and output pins depending upon the respective

voltage levels.

7805 voltage regulator

5.LED

A light-emitting diode (LED) is a semiconductor light source. LEDs are used as indicator

lamps in many devices and are increasingly used for other lighting. Introduced as a practical electronic

component in 1962, early LEDs emitted low-intensity red light, but modern versions are available across

the visible, ultraviolet and infraredwavelengths, with very high brightness.


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When a light-emitting diode is forwardbiased(switched on), electronsare able to recombine

with electron holeswithin the device, releasing energy in the form ofphotons. This effect is called

electroluminescence and the colorof the light (corresponding to the energy of the photon) is

Circuit symbol for LED

determined by the energy gap of the semiconductor. LEDs are often small in area (less than 1 mm2), and

integrated optical components may be used to shape its radiation pattern. LEDs present many advantages

over incandescent light sources includinglower energy consumption, longerlifetime, improved

robustness, smaller size, faster switching, and greater durability and reliability. LEDs powerful enough for

room lighting are relatively expensive and require more precise current and heat management than

compact fluorescent lamp sources of comparable output.

The first practical visible-spectrum (red) LED was developed in 1962 byNick Holonyak Jr., while

working at General Electric Company.

Physics description:

The LED consists of a chip of semiconducting material

doped with impurities to create a p-n junction. As in other diodes,

current flows easily from the p-side, or anode, to the n-side, or

cathode, but not in the reverse direction. Charge-carrierselectrons

and holesflow into the junction from electrodes with different

voltages. When an electron meets a hole, it falls into a lowerenergy level, and releases energy in the form

of aphoton.

The wavelength of the light emitted, and thus its color depends on theband gap energy of the

materials forming the p-n junction. In silicon orgermanium diodes, the electrons and holes recombine by

a non-radiative transition which produces no optical emission, because these are indirect band gap


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materials. The materials used for the LED have a direct band gap with energies corresponding to near

infrared, visible or near-ultraviolet light.

LED development began with infrared and red devices made with gallium arsenide. Advances in materials

sciencehave enabled making devices with ever-shorter wavelengths, emitting light in a variety of colors.

LEDs are usually built on an n-type substrate, with an electrode attached to the p-type layer deposited on

its surface. P-type substrates, while less common, occur as well. Many commercial LEDs, especially

GaN/InGaN, also use sapphire substrate.

Most materials used for LED production have very high refractive indices. This means that

much light will be reflected back into the material at the material/air surface interface. Thus, ligh

extraction in LEDsis an important aspect of LED production, subject to much research and development.

Light-emitting diodes are used in applications as diverse as replacements foraviation lighting, automotive

lighting (particularly brake lamps, turn signals and indicators) as well as in traffic signals. The compact

size, the possibility of narrow bandwidth, switching speed, and extreme reliability of LEDs has allowed

new text and video displays and sensors to be developed, while their high switching rates are also useful in

advanced communications technology. Infrared LEDs are also used in the remote control units of many

commercial products including televisions, DVD players, and other domestic appliances.

6.FILTER

Electronic filters are electronic circuits which perform signal processing

functions, specifically to remove unwanted frequency components from the signal, toenhance wanted ones, or both. Electronic filters can be:

Passive oractive

Analog ordigital

High-pass, low-pass,bandpass,band-reject(band reject; notch), orall-pass.

Discrete-time (sampled) orcontinuous-time

Linearornon-linear

Infinite impulse response (IIR type) orfinite impulse response(FIR type)


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The most common types of electronic filters are linear filters, regardless of other aspects of their design

See the article on linear filters for details on their design and analysis.

Classification by technology

Passive filters

Passive implementations of linear filters are based on combinations of resistors (R), inductors

(L) and capacitors (C). These types are collectively known as passive filters, because they do not depend

upon an external power supply and/or they do not contain active components such as transistors.

Inductors block high-frequency signals and conduct low-frequency signals, while capacitors do the

reverse. A filter in which the signal passes through an inductor, or in which a capacitor provides a path to

ground, presents less attenuation to low-frequency signals than high-frequency signals and is a low-pass

filter. If the signal passes through a capacitor, or has a path to ground through an inductor, then the filter

presents less attenuation to high-frequency signals than low-frequency signals and is a high-pass filter

Resistors on their own have no frequency-selective properties, but are added to inductors and capacitors to

determine the time-constants of the circuit, and therefore the frequencies to which it responds.

The inductors and capacitors are the reactive elements of the filter. The number of elements

determines the order of the filter. In this context, an LC tuned circuitbeing used in a band-pass or band-

stop filter is considered a single element even though it consists of two components.

At high frequencies (above about 100 megahertz), sometimes the inductors consist of single loops or strips

of sheet metal, and the capacitors consist of adjacent strips of metal. These inductive or capacitive pieces

of metal are called stubs.

Single element types

A low-pass electronic filter realized by an RC circuit


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The simplest passive filters, RC andRL filters, include only one reactive element, except hybrid LC filter

which is characterized by inductance and capacitance integrated in one element.

L filter

An L filter consists of two reactive elements, one in series and one in parallel.

T and filters

Low-pass filter

High-pass T filter

Three-element filters can have a 'T' or '' topology and in either geometries, a low-pass, high-

pass,band-pass, orband-stop characteristic is possible. The components can be chosen symmetric or not,

depending on the required frequency characteristics. The high-pass T filter in the illustration, has a very

low impedance at high frequencies, and a very high impedance at low frequencies. That means that it can

be inserted in a transmission line, resulting in the high frequencies being passed and low frequencies being

reflected. Likewise, for the illustrated low-pass filter, the circuit can be connected to a transmission line,

transmitting low frequencies and reflecting high frequencies. Using m-derived filtersections with correct

termination impedances, the input impedance can be reasonably constant in the pass band.

Multiple element types

Multiple element filters are usually constructed as a ladder network. These can be seen as a

continuation of the L,T and designs of filters. More elements are needed when it is desired to improve

some parameter of the filter such as stop-band rejection or slope of transition from pass-band to stop-band


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Active filters

Active filters are implemented using a combination of passive and active (amplifying)

components, and require an outside power source. Operational amplifiers are frequently used in active

filter designs. These can have high Q factor, and can achieve resonance without the use of inductors

However, their upper frequency limit is limited by the bandwidth of the amplifiers used.

Digital filters

A general finite impulse response filter with n stages, each with an independent delay, di and

amplification gain, ai.

Digital signal processingallows the inexpensive construction of a wide variety of filters. The

signal is sampled and an analog-to-digital converterturns the signal into a stream of numbers. A computer

program running on a CPU or a specialized DSP (or less often running on a hardware implementation of

the algorithm) calculates an output number stream. This output can be converted to a signal by passing it

through a digital-to-analog converter. There are problems with noise introduced by the conversions, but

these can be controlled and limited for many useful filters. Due to the sampling involved, the input signal

must be of limited frequency content oraliasingwill occur.

The transfer function

The transfer function of a filter is the ratio of the output signal to that of the input

signal as a function of the complex frequency :

with .


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The transfer function of all linear time-invariant filters, when constructed of discrete

components, will be the ratio of two polynomials in , i.e. a rational function of . The order of the

transfer function will be the highest power of encountered in either the numerator or the denominator.

.

7. LM 386 IC:LM 386 is a low voltage audio power amplifier.

The LM 386 is a power amplifier designed for use in low voltage consumer applications. The

gain is internally set to 20 to keep external part count low, but the addition of an external resistor and

capacitor between pin 1 and pin 8 will increase the gain to any value from 20 to 200.

LM 386 IC pin diagram

The input are ground referenced while the output automatically biases to one half the supply

voltage. The quiescent power drain is only 24milliwatts.When operating from a 6V supply, making the

LM 386 ideal for battery operation.

LM386 Features:

Battery operation.

Maximum external parts.

Wide supply voltage range 4V-12V or 5V-18V.

Low quiescent current drain 4mA.

Voltage gains from 20 to 200.

Ground reference input.


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Applications:

AM-FM radio amplifiers.

Intercoms.

TV sound systems.

Line drivers.

Ultrasonic drivers.

Small servo drivers.

ower converters.

8. SLIDE ON-ON SWITCH

There are three important features to consider when selecting a switch:

Contacts (e.g. single pole, double throw)

Ratings (maximum voltage and current)

Method of Operation (toggle, slide, key etc.)

circuit symbol

Several terms are used to describe switch contacts:

Pole - number of switch contact sets.

Throw - number of conducting positions, single or double.

Way - number of conducting positions, three or more.

Momentary - switch returns to its normal position when released.

Open - off position, contacts not conducting.

Closed - on position, contacts conducting, there may be several on positions.


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For example: the simplest on-off switch has one set of contacts (single pole) and one switching position

which conducts (single throw). The switch mechanism has two positions: open (off) and closed (on), but it

is called 'single throw' because only one position conducts.

Switch Contact Ratings

Switch contacts are rated with a maximum voltage and current, and there may be different

ratings for AC and DC. The AC values are higher because the current falls to zero many times each

second and an arc is less likely to form across the switch contacts.

For low voltage electronics projects the voltage rating will not matter, but you may need to check the

current rating. The maximum current is less for inductive loads (coils and motors) because they cause

more sparking at the contacts when switched off.

ON-ON

Single Pole, Double Throw = SPDT

This switch can be on in both positions, switching on a separate device in each case. It is often called

a changeover switch. For example, a SPDT switch can be used to switch on a red lamp in one position and

a green lamp in the other position.

ON-ON Switch symbol

A SPDT toggle switch may be used as a simple on-off switch by connecting to COM and one of the A

or B terminals shown in the diagram. A and B are interchangeable so switches are usually not labeled.

9. PRESET RESISTOR


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A preset is a three legged electronic component which can be made to offer varying resistance in a

circuit. The resistance is varied by adjusting the rotary control over it. The adjustment can be done by

using a small screw driver or a similar tool.

The resistance does not vary linearly but rather varies in exponential or logarithmic manner. Such variable

resistors are commonly used for adjusting sensitivity along with a sensor.

Preset symbol

These are miniature versions of the standard variable resistor. They are designed to be mounted

directly onto the circuit board and adjusted only whenthe circuit is built. For

example to set the frequency of an alarm tone or the sensitivity of a light-sensitive

circuit. A small screwdriver or similar tool is required to adjust presets.

Presets are much cheaper than standard variable resistors so they are sometimes used

in projects where a standard variable resistor would normally be used.

10. BATTERY

A nine-volt battery, the most common of which (and the one referred to here unless otherwise

stated) is designated a PP3 battery, is shaped as a rounded rectangular prism. 9-volt batteries are

commonly used in pocket transistor radios, smoke detectors, carbon monoxide alarms, guitar effect units

andradio-controlled vehiclecontrollers. They are also used as backup power to keep the time in digita

clocks and alarm clocks.

Nine-volt alkaline batteries are constructed of six individual 1.5V LR61

cells enclosed in a wrapper. These cells are slightly smaller than standard LR8D425

AAAA cellsand can be used in their place for some devices, even though they are 3.5

mm shorter.

As of 2007, 9-volt batteries accounted for 4% of alkaline primary battery sales in the US. In

Switzerland as of 2008, 9-volt batteries totalled 2% of primary battery sales and 2% of secondary battery

sales.


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Connectors

The connector (snap) consists of two connectors: one smaller circular (male) and one larger,

typically either hexagonal or octagonal (female). The connectors on the battery are the same as on the

connector itself; the smaller one connects to the larger one and vice versa.The same connector is used on

most other battery types in the Power Pack(PP) series. The battery has both terminals on one end. Battery

polarization is obvious since mechanical connection is only possible in one configuration.

A problem with this style of connector is that it is very easy to connect two batteries together in

a short circuit, which quickly discharges both batteries, generating heat and possibly a fire. The clips on

the nine-volt battery can be used to connect several nine-volt batteries in series to create higher voltage.

11. PUSHBUTTON

A push-button or simply button is a simple switch mechanism for controlling some aspect of a

machine or a process. Buttons are typically made out of hard material, usually plastic or metal. The

surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or

pushed. Buttons are most often biased switches, though even many un-biased buttons (due to their

physical nature) require a springto return to their un-pushed state. Different people use different terms for

the "pushing" of the button, such as press, depress, mash, and punch.

The "push-button" has been utilized in calculators, push-button telephones, kitchen appliances, and

various other mechanical and electronic devices, home and commercial.

In industrial and commercial applications, push buttons can be linked together by a

mechanical linkage so that the act of pushing one button causes the other button to be released. In this

way, a stop button can "force" a start button to be released. This method of linkage is used in simple

manual operations in which the machine or process have no electrical circuitsfor control.

12. Microphone

A microphone (colloquially called a mic or mike) is an acoustic-to-electric transducerorsensor

that converts sound into an electrical signal. In 1876, Emile Berlinerinvented the first microphone used as

a telephone voice transmitter. Microphones are used in many applications such as telephones, tape

recorders, karaokesystems, hearing aids,motion pictureproduction, live and recorded audio engineering


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FRS radios, megaphones, in radio and television broadcasting and in computers for recording voice,

speech recognition,VoIP, and for non-acoustic purposes such as ultrasonic checking orknock sensors.

Most microphones today use electromagnetic induction (dynamic microphone), capacitance

change (condenser microphone), piezoelectric generation, or light modulation to produce an electrical

voltage signal from mechanical vibration.

A fiber optic microphone converts acoustic waves into electrical signals by sensing changes in

light intensity, instead of sensing changes in capacitance or magnetic fields as with conventional

microphones.

During operation, light from a laser source travels through an optical fiber to illuminate the surface of a

reflective diaphragm. Sound vibrations of the diaphragm modulate the intensity of light reflecting off the

diaphragm in a specific direction. The modulated light is then transmitted over a second optical fiber to a

photo detector, which transforms the intensity-modulated light into analog or digital audio for

transmission or recording. Fiber optic microphones possess high dynamic and frequency range, similar to

the best high fidelity conventional microphones

Fiber optic microphones do not react to or influence any electrical, magnetic, electrostatic or

radioactive fields (this is called EMI/RFI immunity). The fiber optic microphone design is therefore ideal

for use in areas where conventional microphones are ineffective or dangerous, such as inside industria

turbines or in magnetic resonance imaging(MRI) equipment environments.

Fiber optic microphones are robust, resistant to environmental changes in heat and moisture

and can be produced for any directionality or impedance matching. The distance between the

microphone's light source and its photo detector may be up to several kilometers without need for any

preamplifier and/or other electrical device, making fiber optic microphones suitable for industrial and

surveillance acoustic monitoring.

Fiber optic microphones are used in very specific application areas such as for infrasound

monitoring and noise-canceling. They have proven especially useful in medical applications, such as

allowing radiologists, staff and patients within the powerful and noisy magnetic field to converse


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normally, inside the MRI suites as well as in remote control rooms.) Other uses include industrial

equipment monitoring and sensing, audio calibration and measurement, high-fidelity recording and law

enforcement.

13.SPEAKER

A loudspeaker (or "speaker") is an electro acoustictransducerthat produces sound in response

to an electricalaudio signal input. Non-electrical loudspeakers were developed as accessories to

telephone systems, but electronic amplification by vacuum tube made loudspeakers more generally 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 of the 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 in theatres and concerts,

and in public address.

CHAPTER:3

3.1 CIRCUIT DIAGRAM


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Figure: 1circuit diagram

3.2 Functional Description:

APR9600 block diagram is included in order to describe the device's internal architecture. At

the left hand side of the diagram are the analog inputs. A differential microphone amplifier, including

integrated AGC, is included on-chip for applications requiring use. The amplified microphone signals fed

into the device by connecting the ANA_OUT pin to the ANA_IN pin through an external DC blocking

capacitor. Recording can be fed directly into the ANA_IN pin through a DC blocking capacitor, however,

the connection between ANA_IN and ANA_OUT is still required for playback. The next block

encountered by the input signal is the internal anti-aliasing filter. The filters automatically adjust itsresponse according to the sampling frequency selected so Shannons Sampling Theorem is satisfied. After

anti-aliasing filtering is accomplished the signal is ready to be clocked into the memory array. This storage


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is accomplished through a combination of the Sample and Hold circuit and the Analog Write/Read circuit.

These circuits are clocked by either the Internal Oscillator or an external clock source

Figure2: The APR9600 DIP & SOP is not [PIN TO PIN]

When playback is desired the previously stored recording is retrieved from memory, low pass

filtered, and amplified as shown on the right hand side of the diagram. The signal can be heard byconnecting a speaker to the SP+ and SP- pins. Chip-wide management is accomplished through the device

control block shown in the upper right hand corner. Message management is provided through the

message control block represented in the lower center of the block diagram. More detail on actual device

application can be found in the Sample Application section. More detail on sampling control can be found

in the Sample Rate and Voice Quality section. More detail on Message management and device control

can be found in the Message Management section.


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Figure 3 APR9600 Block Diagram

3.3Message Management:

Playback and record operations are managed by on-chip circuitry. There are several available

messaging modes depending upon desired operation. These message modes determine message

management style, message length, and external parts count. Therefore, the designer must select the

appropriate operating mode before beginning the design. Operating modes do not affect voice quality; for

information on factors affecting quality refer to the Sampling Rate & Voice Quality section. The device

supports five message management modes (defined by the MSEL1, MSEL2 and /M8_OPTION pins

shown in Figures 1 and 2):

Random access mode with 2, 4, or 8 fixed-duration messages Tape mode, with multiple variable-

duration messages, provides two options:

-Auto rewind

-Normal Mode cannot be mixed. Switching of modes after the device has recorded an initial message

is not recommended. If modes are switched after an initial recording has been made some unpredictable

message fragments from the previous mode may remain present, and be audible on playback, in the new

mode. These fragments will disappear after a Record operation in the newly selected mode. Table 1


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defines the decoding necessary to choose the desired mode. An important feature of the APR9600

Message management capabilities is the ability to audibly prompt the user to change in the device's status

through the use of "beeps" superimposed on the device's output. This feature is enabled by asserting a

logic high level on the BE pin.

Tabel: 2

The APR9600 device incorporates several features design help simplify microprocessor

Controlled message management When controlling messages the microprocessor essentially toggles pins

as described in the message management sections described previously. The /BUSY, /STROBE, and

/M7_END pins are included to simplify handshaking between the microprocessor and the APR9600

The /BUSY pin, when low, indicates to the host processor that the device is busy and that No commands

can be accepted. When this pin is high the device is ready to accept and execute commands from the host.

The /STROBE pin pulses low each time a memory segment is used. Counting pulses on this pin enablesthe host processor to accurately determine how much recording time has been used, and how much

recording time remains. The APR9600 has a total of eighty memory segments. The /M7_END pin is used

as an indicator that the device has stopped its current record or playback operation.

During recording a low going pulse indicates that all memory has been used. During playback

a low pulse indicates that the last message has played. Microprocessor control can also be used to link

several APR9600 devices together in order to increase total available recording time. In this application

both the speaker and microphone signals can be connected in parallel. The microprocessor will then

control which device currently drives the speaker by enabling or disabling each device using its respective

/CE pins.

A continuous message cannot be recorded in multiple devices however because the transition


Mode MSEL1 MSEL2 /M8_OPTION

Random Access 2 fixed duration messages 0 1 Pull this pin to VCC through l00K resistor

Random Access 4 fixed duration messages 1 0 Pull this pin to VCC through l00K resistor

Random Access 8 fixed duration messages 1 1 The /M8 message trigger becomes input pin

Tape mode, Auto rewind operation 0 0 0

Tape mode, Normal operation 0 0 1

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from one device to the next will incur a delay that is noticeable upon playback. For this reason it is

recommended that message boundaries and device boundaries always coincide.

3.4 Random Access ModeRandom access mode supports 2, 4, or 8 Message segments of fixed duration. As suggested

recording or playback can be made randomly in any of the selected messages. The length of each message

segment is the total recording length available (as defined by the selected sampling rate) divided by the

total number of segments enabled (as decoded in Table1). Random access mode provides easy indexing to

message segments.

3.4.1 Functional Description of Recording in Random Access Mode

On power up, the device is ready to record or playback in any of the enabled message

segments. To record,/CE must be set low to enable the device and /RE must be set low to enable

recording. You initiate recording by applying a low level on the message trigger pin that represents the

message segment you intend to use. The message trigger pins are labeled /M1_MESSAGE -

/M8_OPTION on pins 1-9 (excluding pin 7) for message segments 1-8 respectively. Note: Message

trigger pins of M1_MESSAGE,/M2_NEXT, /M7_END, and /M8_OPTION, have expanded names to

represent the different functionality that these pins assume in the other modes. In random access mode

these pins should be considered purely message trigger pins with the same functionality as /M3, /M4, /M5

and /M6. For a more thorough explanation of the functionality of device pins in different modes please

refer to the pin description table that appears later in this document. When actual recording begins the

device responds with a single beep (if the BE pin is high to enable the beep tone) at the speaker outputs to

indicate that it has started recording. Recording continues as long as the message pin stays low. The rising

edge of the same message trigger pin during record stops the recording operation (indicated with a single

beep).If the message trigger pin is held low beyond the end of the maximum allocated duration, recording

stops automatically (indicated with two beeps), regardless of the state of the message trigger pin. The chip

then enters low-power mode until the message trigger pin returns high. After the message trigger pin

returns to high, the chip enters standby mode. Any subsequent high to low transition on the same message

trigger pin will initiate recording from the beginning of the same message segment. The entire previous


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message is then overwritten by the new message, regardless of the duration of the new message

Transitions on any other message trigger pin or the /RE pin during the record operation are ignored until

after the device enters standby mode.

3.4.2Functional Description of Playback in Random Access Mode

On power up, the device is ready to record or playback, in any of the enabled message

segments. To playback,/CE must be set low to enable the device and /RE must be set high to disable

recording & enable playback. You initiate playback by applying a high to low edge on the message trigger

pin that represents the message segment you intend to playback. Playback will continue until the end of

the message isreached. If a high to low edge occurs on the same message trigger pin during playback

playback of the current message stops immediately. If a different message trigger pin pulses during

playback, playback of the current message stops immediately (indicated by one beep) and playback of the

new message segment begins. A delay equal to 8,400 cycles of he sample clock will be encountered

before the device starts playing the new message. If a message trigger pin is held low, the selected

message is played back repeatedly as long as the trigger pin stays low. A period of silence, of duration

equal to 8,400 cycles of the sampling clock, will be inserted during looping as an indicator to the user of

the transition between the end and the beginning of the message.

3.5 Signal Storage:

The APR9600 samples incoming voice signals and stores the instantaneous voltage samples in

non-volatile FLASH memory cells. Each memory cell can support voltage ranges from 0 to 256 levels.

These 256 discrete voltage levels are the equivalent of 8-bit (28=256) binary encoded values. During

playback the stored signals are retrieved from memory, smoothed to form a continuous signal, and then

amplified before being fed to an external speaker.

3.6 Sampling Rate & Voice Quality:

According to Shannon's sampling theorem, the highest possible frequency componen

introduced to the input of a sampling system must be equal to or less than half the sampling frequency if

aliasing errors are to be eliminated. The APR9600 automatically filters its input, based on the selected

sampling frequency, to meet this requirement. Higher sampling rates increase the bandwidth and hence the


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voice quality, but they also use more memory cells for the same length of recording time. Lower sampling

rates use fewer memory cells and effectively increase the duration capabilities of the device, but they also

reduce incoming signal bandwidth. The APR9600 accommodates sampling rates as high as 8 kHz and as

low a 4 kHz. You can control the quality/duration trade off by controlling the sampling frequency.

An internal oscillator provides the APR9600 sampling clock. Oscillator frequency can be Changed by

changing the resistance from the OscR pin to GND. Table 2 summarizes resistance values and the

corresponding sampling frequencies, as well as the resulting input bandwidth and duration.

Table :3 Resistance Values & Sampling Frequencies

3.7 Automatic Gain Control (AGC) :

The APR9600 device has an integrated AGC. The AGC affects the microphone input but does

not affect the ANA_IN input. The AGC circuit insures that the input signal is properly amplified. The

AGC works by applying maximum gain to small input signals and minimum gain to large input signals

This assures that inputs of varying amplitude are recorded at the optimum signal level. The AGC amplifier

is designed to have a fast attack time and a slow decay time. This timing is controlled by the RC network

connected to pin 19. A value of 220K and 4.7uF has been found to work well for the English language. Be

aware that different languages, speakers from different countries, and music may all require modificationof the recommended values for the AGC RC network.


ResistanceSampling FrequencyInput Bandwidth

Duration

84 K 4.2 kHz 2.1 kHz 60 sec

38 K 6.4 kHz 3.2 kHz 40 sec

24 K 8.0 kHz 4.0 kHz 32 sec

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4.1 APPLICATIONS

Doorbell or entrance message. Greet your guests or customers with a welcome message.

Watchdog" burglar alarm system. Record the barking of a dog and connect this circuit to a alarm

system to deter burglars.

Toys applications where you need speech or audio effects.

Talking picture frames for personal or museum use. Add it to the back of a picture frame of a friend or

relative to have his or her voice be played back at any time.

With the looping mode of operation, you can connect the circuit to one of our FM Transmitters in order

to build a FM Announcement System or talking sign which is ideal for real estate applications.

4.2 ADVANTAGES

Single-chip, high-quality voice recording &

Playback solution

- No external ICs required

- Minimum external components

Non-volatile Flash memory technology

- No battery backup required

User-selectable messaging options

- Random access of multiple fixed-duration

messages

- Sequential access of multiple variable duration

Message.


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REFERENCES


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