Mini Project Documentation2

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POWER SUPPLY FAILURE ALARM

Mini Project Report

Submitted in partial fulfillment of the requirements

For the award of the degree of

Bachelor of Technology

In

ELECTRONICS & COMMUNICATION ENGNEERING

By

SYED. HUSSAIN 08UK1A0436M. RADHA 08UK1A0413

A. MADHAVI 08UK1A0419

L. DEVSINGH 08UK1A0412

Under guidance of

Mr. J. LingaiahAsst. Prof

DEPARTMENT OF ELECTRONIC & COMMUNICATIONENGINEERING

VAAGDEVI ENGINEERING COLLEGE, WARANGAL

(Affiliated to JNTU HYDERABAD)

Department of Electronic & communication Engineering

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VAAGDEVI ENGINEERING COLLEGE

P.O.BOLLIKUNTA, WARANGAL- 506 005

CERTIFICATE

This is to certify that the mini project report enlited POWER SUPPLY FAILURE

ALARM Is being submitted by Mr. SYED. HUSSAIN, M. RADHA, A.

MADHAVI, L. DEVSINGH Bearing H.T.No. 08UK1A0436, 08UK1A0413,08UK1A0419, 08UK1A0412 in partial fulfillment of the requirements for the award of the

degree in Bachelor of Technology in Electronics & Communication

Engineeringtojntu Hyderabad is a bonafide work carried out by him under my guidance

and supervision during academic year 2010-2011.

The result presented in this report has not submitted to any other university or

institution for the award of any degree or diploma.

J. Lingaiah CH. SURESH KUMAR A. RAJI REDDY

Guide Head of the Department Principal

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ACKNOWLEDGEMENT

With immense pleasure we would like to take this opportunity to place it on record

that POWER SUPPLY FAILURE ALARM has taken shape, but without thecooperation extended to us by certain individuals it wouldnt have been possible. We

consider it as a privilege to thank all those persons who have helped us in completing this

project.

We express a sincere and profound gratitude toA.RajiReddy, principalof Vaagdevi

engineering college for his support help, guidance and encouragement in the course of our

project.

We are very thankful to Mr.Suresh Kumar, Head of the dept. of electronics and

communication engineering of vaagdevi engineering college, Bollikunta for providing

necessary facilities in carrying out this project.

We wish to express my deepest sense of gratitude to my guide Mr.J.Lingaiah, for his

inspiring and expert guidance throughthe tenure of this work, his encouragement and open-

minded discussions have been a source of inspiration during this project.

We acknowledge the help and cooperation of all teaching and non-teaching staff who

have helped us in completion of this project successfully.

We apologize for any oversights and inaccuracies in our acknowledgment.


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CONTENTS

Abstract 1

Chapter 1.Introduction 2

1.1Field of Invention

1.2Background of Invention

Chapter 2.Architecture Overview 3

2.1 Project Description

2.2Circuit Diagram

Chapter 3.Hardware section 6

3.1 Resistor

3.2 Capacitor

3.3 Diode

3.4 Transistor BC558

3.5 LED

3.6Piezo Buzzer3.7 Mains Supply

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Chapter4.Appendix 17

i. Fabrication Of PCB

ii. List Of Components Used

Chapter 5.APPLICATIONS 21

Conclusion 22

Bibliography 23

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ABSTRACT

A power failure alarm for use in sounding a warning in the occasion of a power failure,

with built in electrical connectors, and a temporary source of light. The device is housed in

a molded plastic enclosure in a rectangular shape and includes an emergency light, night-

light, flashlight, and power failure alarm. All unit functions are completely automatic once

the unit has been plugged into a standard 120 volt receptacle. The device has a three prong

male plug on the back of the body and is designed to occupy one receptacle of a duplex

receptacle thus leaving one receptacle still available for use. Alternate embodiments of the

device are specifically intended to alert and notify the user of a power failure. The device

utilized logic circuitry to determine if a power failure or improper setup has occurred. The

battery charging and monitoring circuits ensure the batteries are always charged and ready

for use.

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CHAPTER-1

INTRODUCTION

1.1 FIELD OF INVENTION:

The present invention relates to a power failure alarm device, and more particularly, to a device

that not only generates an audible signal to indicate when a connected power source has failed,

but also is configured to incorporate a portable lamp and may be used in a variety of

applications including refrigeration. An option available on this device will also alert the user

when a power failure has occurred when connected to a standard dialup phone line.

1.2 BACKGROUND OF THE INVENTION:

Numerous electrical appliances in home and commercial businesses require a continuous

supply of electrical power in order to function, such as refrigerators, freezers, lamps,

computers, clocks, and critical medical equipment. Most of these devices gain electrical power

by connecting to a main power supply via a plug into a wall receptacle. However, on occasions

these devices may become inoperable through a power failure, accidental unplugging, turning

off the power switch, or a tripped circuit breaker. These occasions can happen without

becoming noticeable. It is not uncommon for a motor driven appliance to fail and open the fuse

or circuit breaker. Quite often a homeowner is not aware of the motor failure until it is too late,

for example refrigerated food is spoiled or the basement is flooded.

Supermarkets use multiple refrigerators providing open storage of chilled or frozen foods, thus

if an unnoticed power failure occurs, the consequence would result in a large loss of inventory

and revenue. Even though most commercial refrigeration is monitored by temperature alarmsystems, an alarm on the power source would provide early warning of an imminent

temperature rise.

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CHAPTER 2ARCHITECTURE OVERVIEW

Most of the power-supply failure indicator circuits need a separate power-supply for themselves. But the

alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to

store adequate charge, to feed power to the alarm circuit which sounds an alarm for a reasonable duration

when the mains supply fails.

1. During the presence of mains power supply, the rectified mains voltage is stepped down to a required

low level. A zener is used to limit the filtered voltage to 15-volt level. Mains presence is indicated by an

LED. The low-level DC is used for charging capacitor C3 and reverse biasing switching transistor

T1. Thus, transistor T1 remains cut-off as long as the mains supply is present. As soon as the mains

power fails, the charge stored in the capacitor acts as a power-supply source for transistor T1. Since, inthe absence of mains supply, the base of transistor is pulled low via resistor R8, it conducts and sounds

the buzzer (alarm) to give a warning of the power-failure.

2. With the value of C3 as shown, a good-quality buzzer would sound for about a minute. By increasing

or decreasing the value of capacitor C3, this time can be altered to serve ones need.

3. Assembly is quite easy. The values of the components are not critical. If the alarm circuit is powered

from a many external DC power-supply source, the mains-supply section up to poin ts P and M can be

omitted from the circuit. Following points may be noted.

i. At a higher DC voltage level, transistor T1 (BC558) may pass some collector-to-emitter leakage

current, c causing a continuous murmuring sound from the buzzer. In that case, replace it with some low-

gain transistor

ii. Piezo buzzer must be a continuous tone version, with built-in oscillator.

To save space ,one may use five small sized 1000F capacitors (in parallel) in place of bulky high-value

capacitor C3.

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2.2 Project Description:

This project is power supply monitoring device that will trigger a buzzer when the mains

supply cuts off. At the same time, the light emittingdiode will be turned ON. This device is

helpful to inform the loss of power supply to some critical installation such as a pump in a fish

tank. Once the buzzer sound, one will know that there is a loss of power supply and actions

need to be taken to rectify the situation by providing alternative power supply or relocating the

installation.

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4. Most of the power supply failure indicator circuits need a separate power supply for themselves. But

the alarm circuit presented here needs no additional supply source. It employs an electrolytic capacitor to

store adequate charge, to feed power to the alarm circuit which sounds an alarm for a reasonable

duration.

This circuit can be used as an alarm for power supplies in the range of 5V to 15V.

To calibrate the circuit, first connect the power supply (5 to 15V) then vary the potentiometer VR1 until

buzzer goes from on to off .Whenever the supply fails, resistor R2 pulls the base of transistor low and

saturates it, turning the buzzer ON.

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http://www.electronicsforu.com/efylinux/circuit/jul2000/power.gif


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CHAPTER-3

HARDWARE SECTION

3.1 RESISTOR:

Adevice used in electricalcurrent conduction tocontrol thedirection of the current flowing

to acircuitby applying resistance. Resistors may be fixed or variable both controlling the

flow of current differently. It is sometimes not obvious whether a color coded component is a

resistor, capacitor, or inductor, and this may be deduced by knowledge of its circuit function,

physical shape or by measurement. Resistor values are always coded

inohms ,capacitors inpicofarads (pF), andinductors inmicro henries

ColorSignificant

figuresMultiplier Tolerance

Temp.

Coefficient

(ppm/K)

Black 0 10 250 U

Brown 1 10 1% F 100 S

Red 2 10 2% G 50 R

Orange 3 103 15 P

Yellow 4 10 (5%) 25 Q

Green 5 105 0.5% D 20 Z

Blue 6 10 0.25% C 10 Z

7 107 0.1% B 5 M

fig 3.1 color coding of Resistors

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Gray 8 10

8

0.05%

(10%) A 1 K

White 9 109

Gold 10-1

5% J

Silver 10-2 10% K

None 20% M
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The standard color code perEN 60062:2005 is as follows:

3.12 Capacitor:

Fig 3.12 Electrolytic Capacitor

A capacitor (formerly known as condenser) is a device for storing electric charge. The forms of

practical capacitors vary widely, but all contain at least two conductors separated by a non-

conductor. Capacitors used as parts of electrical systems, for example, consist of metal foils

separated by a layer of insulating film.

A capacitor is apassiveelectronic component consisting of a pair ofconductors separated by

adielectric.When there is apotential difference (voltage) across the conductors, a

staticelectric field develops across the dielectric, causing positive charge to collect on one plate

and negative charge on the other plate.Energy is stored in the electrostatic field. An ideal

capacitor is characterized by a single constant value ,capacitance,measured infarads.This is

the ratio of theelectric charge on each conductor to the potential difference.

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3.13 Theory of operation:

Charge separation in a parallel-plate capacitor causes an internal electric field. A dielectric

reduces the field and increases the capacitance.

fig 3.13 parallel plate capacitor

A capacitor consists of twoconductors separated by a non-conductive region. The non-

conductive region is called the dielectric or sometimes thedielectric medium.In simpler terms,

the dielectric is just anelectrical insulator. Examples of dielectric mediums are glass, air,

paper,vacuum, and even asemiconductordepletion region chemically identical to the

conductors. An ideal capacitor is wholly characterized by a constant capacitance C, defined as

the ratio of charge Qon each conductor to the voltage Vbetween them

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Sometimes charge build-up affects the capacitor mechanically, causing its capacitance to

vary. In this case, capacitance is defined in terms of incremental changes:

Energy storage:

C=

W= = dq

Current-voltage relation:

.() () ()() Thedual of the capacitor is theinductor,which stores energy in themagnetic field rather than

the electric field. Its current-voltage relation is obtained by exchanging current and voltage in

the capacitor equations and replacing Cwith the inductanceL.

3.14 DC circuits

Fig 3.14 RC Circuit

fromKirchhoff's voltage law that

() () ()()

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Taking the derivative and multiplying by C, gives afirst-order differential equation,

() ()

At t= 0, the voltage across the capacitor is zero and the voltage across the resistor is V0. The

initial current is then i(0) =V0/R. With this assumption, the differential equation yields

where

0=RCis thetime constant of the system.

3.15 AC circuits

Impedance,the vector sum ofreactance andresistance,describes the phase difference and the

ratio of amplitudes between sinusoidally varying voltage and sinusoidally varying current at a

given frequency.Fourier analysis allows any signal to be constructed from aspectrum of

frequencies, whence the circuit's reaction to the various frequencies may be found. The

reactance and impedance of a capacitor are respectively

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3.2 HAZARDS AND SAFETY:

Capacitors may retain a charge long after power is removed from a circuit; this charge can

cause dangerous or even potentially fatalshocks or damage connected equipment. For example,

even a seemingly innocuous device such as a disposable camera flash unit powered by a 1.5voltAA battery contains a capacitor which may be charged to over 300 volts. This is easily

capable of delivering a shock. Service procedures for electronic devices usually include

instructions to discharge large or high-voltage capacitors.

Capacitors may also have built-in discharge resistors to dissipate stored energy to a safe level

within a few seconds after power is removed.

High-voltage capacitors restored with the terminalsshorted, as protection from potentially

dangerous voltages due todielectric absorption.

ZENER Diodes:

Diodes that can be made to conduct backwards. This effect, called Zener breakdown, occurs at

a precisely defined voltage, allowing the diode to be used as a precision voltage reference. In

practical voltage reference circuits Zener and switching diodes are connected in series and

opposite directions to balance the temperature coefficient to near zero.

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3.3 TRANSISTOR:

The BC558is a general purposesiliconNPNBJTtransistor found commonly in European

electronic equipment; the part number is assigned byPro Electron, which allows many

manufacturers to offer electrically and physically interchangeable parts under one

identification. The BC548 is commonly available in European Union and Commonwealth

Countries and is often the first type of bipolar transistor young hobbyists encounter. The

BC548 is often featured in circuit diagrams and designs published in Electronics Magazines

such as "Silicon Chip" and "Elektor".

Fig 3.3.1 BC558 Transistor

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3.4 LED:

.

fig 3.4.1 Structure of LED

LED spotlight using 38 individual diodes for mains voltage power

A LED is asemiconductor light source. LEDs are used as indicator lamps in many devices and

are increasingly used for other lighting. LEDs emitted low-intensity red light, but modern

versions are available across thevisible,ultraviolet andinfrared wavelengths, with very high

brightness. When a light-emittingdiode is forwardbiased ,electrons are able

torecombine withelectron holes within the device, releasing energy in the form ofphotons.

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This effect is calledelectroluminescence and thecolor of the light (corresponding to the

energy of the photon) is determined by theenergy gap of the semiconductor. An LED is often

small in area (less than 1 mm2), and integrated optical components may be used to shape its

radiation pattern. LEDs present manyadvantages 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 andheat management than

compactfluorescent lamp sources of comparable output.

Fig 3.4.2 Internal Diagram Of LED

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3.5 BUZZER:

fig 3.5.1 Buzzer

A piezoelectric disk generates a voltage when deformed (change in shape is greatly

exaggerated).

A piezoelectric sensor is a device that uses thepiezoelectric effect To

measurepressure,acceleration,strain orforceby converting them to anelectrical charge.

One disadvantage of piezoelectric sensors is that they cannot be used for truly static

measurements. A static force will result in a fixed amount of charges on the piezoelectric

material. While working with conventional readout electronics, imperfect insulating materials,

and reduction in internal sensorresistance will result in a constant loss ofelectrons,and yield a

decreasing signal.

3.6 MAINS SUPPLY:

Mains is the general-purposealternating current (AC)electric power supply. 240V (always

expressed asroot-mean-square voltage). The two commonly used frequencies are 50 Hz and

60Hz.Worldwide, many differentmains power systems are found for the operation of

household and light commercial electrical appliances and lighting. The different systems are

primarily characterized by their Voltage, Frequency Plugs and socketsbut also by their

Earthing system (grounding).Protection againstover current damage (e.g., due to short

circuit),electric shock,and fire hazards

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Fig 3.6.1 Main Supply Voltage

3.6.1 Measuring voltage

A distinction should be made between the voltage at the point of supply (nominal system

voltage) and the voltage rating of the equipment (utilization voltage). Typically the utilization

voltage is 3% to 5% lower than the nominal system voltage; for example, a nominal 208 V

supply system will be connected to motors with "200 V" on their nameplates. This allows for

thevoltage dropbetween equipment and supply. Voltages in this article are the nominal supply

voltages and equipment used on these systems will carry slightly lower nameplate voltages.

Power distribution system voltage is nearly sinusoidal in nature. Voltage tolerances are for

steady-state operation. Momentary heavy loads, or switching operations in the power

distribution network, may cause short-term deviations out of the tolerance band. In general,

power supplies derived from large networks with many sources are more stable than those

supplied to an isolated community with perhaps only single generator.

Utility frequency:

At the end of 19th century, Westinghouse in the US decided on 60 Hz and AEG in Germany

decided on 50 Hz, eventually leading to the world being mostly divided into two frequency

camps. Most 60 Hz systems are nominally 120 volts and most 50 Hz nominally 230 volts.

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CHAPTER -4

APPENDIX

i.FABRICATION OF PCB

ii.List Of Components Used

4.1 INTRODUCTION:

The design of a PCB can be considered at the last step in electronic design as well as first major

step in the production of PCBs. It forms a distinct factor in the electronic Ckt, performance and

reliability. The producibility of PCB and its assembly and serviceability also depends on the

design. The layout of a PCB has to incorporate all the information on the board before one can

go to artwork preparation. Designing a Ckt in to a smaller one is difficult task to perform. The

detailed Ckt diagram is very important for the layout designer, but he must also familiar with

designing concept and with philosophy behind the equipment with use of PCB, the task of the

problem &rectification becomes very simple.

TYPES OF PCBs:

1.single sideboards

2. double sideboards

4.12 SINGLE SIDE BOARD:

For single sideboard, the conducting copper clad is only on one side of non-conducting

hylam a sheet. From one side the components are placed & soldered on the other side of

the PCB. The cost of such PCBs is minimum is very easy to trace.

These PCBs are mostly used in entertainment electronics where manufacturing costs

have to be kept low. However in industrial applications, the cost factor can be neglected

& single sided boards are used where particular Ckt is small & simple enough to be

accommodated on such PCBs. To jump over the conductor tracks components have to

be utilized. This is not feasible, jumper wires are used. The number of on the board,

however, it is restricted by economic reasons. If their number is more than a few then

the use of double sided PCBs is considered.

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4.2 THE ULTRA SONIC PROXIMITY DETECTOR IS

CONSTRUCTED ON A SINGLE SIDED BOARD AS SHOWN:

4.2.1 PCB DESIGN:

to design a PCB layout must essentially to solve two tasks;

one is to design the inter connections for the components.

To minimize the magnitude and influence of the parasitic effects connected with the

realization of such interconnections.

The resistance or inductance of a conductor or the capacitance between the two

conductors can cause parasitic effects influence working electronic circuit on o PCB.

4.2.2 ARTWORK:

The generation of PCB artwork should be considered as the first step of the PCB

manufacturing process. The importance of the artwork should not be under estimated.

Problems like inaccurate of registration, broken annual rings, or too critical spacing are

often due to bad artwork. And even with the most sophisticated PCB production

facilities, no PCB can be made better than the quality of artwork used. A common

necessity for an artwork is needed for a clean and exact working, which means taking

care of the smallest details.4.2.3 SCREEN PRINTING:

The process of screen-printing is well known to the primary industry. Its inherent

capabilities of printing a wide range of inks on almost and kind of surface including

metals, plastic, fabrics, wood, etc.,

But only of dimensionally high accurate and sable fine mesh fabrics of mono file

materials made the screen-printing process applicable to fabrication of printed circuit

boards.

The screen-printing process is particularly suitable for large-scale production process.

however, the preparations screen can also be economically attractive for a series of 100

PCBs or below.

While photo printing is more accurate method to transfer a pattern onto a board surface.

Screen-printing is considerable cheaper way to do a sufficient job for large series. With

the screen-printing process, one can produce PCBs of as low 0.5 to 0.1mm and a

registration error of 0.1mm on an industrial scale with high reliability.

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Therefore, screen-printing is a method by which worldwide largest numbers of PCB

patterns are printed. The screen-printed boards are typically processed in the print and

etch process.

In its basic form, the screen-printing process is very simple. A screen fabric with

uniform meshes and openings is stretched and fixed on a solid frame of metal or wood.

The circuit pattern is photographically transferred on the screen, leaking the meshes in

the pattern open, with the meshes in the pattern open, with the meshes in the rest of the

area are closed. In actual printing step, ink is forced by moving the squiggle through the

open meshes on to the surface of the material to be printed.

4.4.4 ETCHING:

In all substructure PCB process, etching is one of the most important steps;

The final copper pattern is formed by the selective removal of all unwanted copper,

which is not protected by an etch resist. This looks very simple at the glance but in

factors like under etching and overhang complicate the matter especially in the

production of fine and highly precise PCBs.

4.4.5 UNDER ETCHING:

During the etching process, it is expected that etching progress vertically. However,

there is also an etching action sideways which attack the pattern below the etch resist. If

the etching action is not stopped immediately after all unwanted copper has been

removed, under etching will continue and can lead to considerable reduction of

conductor line width.

4.4.6 OVER HANG:

The exact control of the conductor width is further complicated where metal etch resist

are used i.e., in pattern planting processes. The metal planting built up shows growth

sideways also, resulting in over hang. The difficulties of overhang are reduced with the

use of dry film resist.

4.7 TYPES OF ETCHANTS:

Tank or bubble etching, in which boards are kept in rack, are lowered and full vide the

fast, precise and uniform production, which is desired in todays electronic production.

Another etching method is etching with a splash type etching machines. In these

machines, etching is thrown by a centrifugal force via a routing device in the center of

etching machines on the surface of the surrounding boards .latest versions of etching

machines available.19


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4.8 ETCHING SYSTEMS:

When it comes to the choice of the most suitable etching system for a PCB production

process, there are many factors to be considered. Firs it has to be matched to the etch

resist used i.e., the etch resist should not allow the action of etching on the copper layer

beneath it. Screen and photo resist can be either solvent or aqueous soluble type. The

resist soluble in aqueous solution are not suitable for alkali etchings, but they offer

sufficient other advantage with respect to environmental pollution and easy removal.

Among many of the etchings ferric chloride was the earliest one used on massive scale.

This is recommended for small PCB facilities where etching is occasionally carried out

on a small number of boards.

4.8.1 FERRIC CHLORIDE:

Ferric chloride is an etching very simple to use especially in case of small scale PCB

production. In high volumes of productions this is not of much importance because it

can hardly be regenerated and it attacks the common metal etch resists.

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CHAPTER-5

APPLICATIONS

1.Power supply circuits are most commonly used in domestic appliances i.e, household

purposes.

2.Helpful to inform the loss of power supply with the help of a BUZZER.

3.Easy to install due its simple circuitry.

4.Low cost with high reliability.

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CONCLUSION

This project POWER SUPPLY FAILURE ALARM can be helpful to know the information

about the power loss by placing a BUZZER & even it supports placing another LED at the

output side in turn resulting in proper usage of power in absence of mains supply.

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BIBLIOPGRAPHY:

1.LINEAR IC APPLICATIONS BY ROY CHOWDGARY

2.ELECTRONIC DEVICES AND CIRCUITS BY SALIVAHANAN

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Date post:	04-Jun-2018
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