car light control-final

7/27/2019 Car Light Control-final

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SETH JAI PARKASH MUKAND LAL

INSTITUTE OF TECHNOLOGY, RADAUR

TO WARDS PRATIAL FULLFILLMENT OF THE REQUIREMENT

OF KURUKSHETRA UNIVERSITY

FOR BECHLOR OF TECHNOLOGY

IN MECNICAL ENGINEERING

PROJECT ON

CAR STEERING OPRATEDFRONT LIGHT

PREPARED AND SUBMITTED BY

SANJEEV K.PRABHAKAR ROLL NO.212154

SUNIL KUMAR ROLL NO.212152

RAJESHWAR ROLL NO.212159

SUBMITTED TO :-

MS. MAMTA JAIN MR. V.K. VERMA(PROJECT INCHARGE) H.O.D. (MECH.-ENGG.)

DEPARTMENT OF MECHANICAL ENGINEERING

RADAUR


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CertificateCertified that the Project entitledCAR STEERING

OPRATED FRONT LIGHT is prepared and submitted by

This is the record of the work carried out by the group

Under our supervision and guidance.

This is further certified that, they have worked with zeal for the

complete semester for preparing this project.


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Acknowledgement

After completing our projectCAR STEERING OPRATED

FRONT LIGHT, We wish to express my obligations to thecollege staff. We wish to express our obligations to our fellow

project markers.

We would like to thank and pay our obligations

(H.O.D.-Mech. Engg.) for his guidance

regarding the project. We would like to pay our special gratitude

to (Project Incharge) for her every ready helps.

We are also grateful to our family and friends for tolerating our

infrequent appearances over the period of realizing this project.

ForCAR STEERING OPRATED FRONT LIGHT


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Foreword

The present project on CAR STEERING OPRATED FRONT

LIGHTis yet another contribution by Mr. Sanjeev K.Prabhakar (RollNo.212154), Mr. Sunil Kumar (Roll No.212152), Mr. Rajeshwar (Roll

No.212159), Mr.Suresh Kumar (Roll No.212161) Praveen Kumar Roll

(No.212156) and Mr. Pradeep Kumar (Roll No.212182), students 7th

sem. G.B.P.P. Okhla, in their efforts to develop basic informative and

instructive material for analysis and design ofCAR STEERING

OPRATED FRONT LIGHT. This report has been written as apart of the program of minor project as recommended by Borad ofTechnical Education Delhi as a part of curriculum in the starting of

7th semester of m...

Writing a report on technical aspect is indeed a very challenging task.

The student has to possess not only expertise in the subject matter but

also the technique of selecting appropriate material from the vast fund

of knowledge they have to have regarding the subject of project and

present it in a way which the readers can easily understand. Judgingfrom the remarks of the experts who reviewed the report and also on

the basis of earlier projects by these students in the Mechanical field. I

have no doubt in my mind that they had done an excellent job.

The institute will, therefore fell amply rewarded if the other students

and teachers may go through this report for enlarging their know how

ofCAR STEERING OPRATED FRONT LIGHT. Anysuggestions for the improvement of this project and the report from all

quarters will be most welcome.


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Contents

1. CERTIFICATE..........................................................................6

2. COMPONENTS USED.................7

3. ACKNOWLEDGEMENT.................................................8

4. FOREWORD..............................................................9

5. INTRODUCTIONS......................................................9

6. METHODOLOGIES.............................................10

7. HOW OUR MODEL WORKS........................................16

8. APPROXIMATE COST...........................................................19

9. CONCLUSIONS..................................................23

10. APPLICATIONS.........................................25

11. USES.............................................................25

12. WORKING COMPONENTS DETAIL....................................26


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5. INTRODUCTIONS

A FRONT LAMP STEERING CONTROLLED LIGHT DISTRIBUTION

SYSTEM IS DISCLOSED HAVING A LIGHT DISTRIBUTION MEANS

MOVABLE TO VARY A LIGHT DISTRIBUTION PATTERN TO RIGHT

AND LEFT MAXIMUM LIMIT POSITIONS IN CORNERING AREAS

OF A VEHICLE, AND A CONTROL MEANS RESPONSIVE TO A

TURNED ON STATE OF A HEAD LAMP SWITCH FOR ACTUATINGTHE LIGHT DISTRIBUTION MEANS TO CAUSE THE LIGHT

DISTRIBUTION PATTERN TO BE VARIED ACCORDING TO A

STEERING DIRECTION.


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6. METHODOLOGIES

WE ARE CONSTRUCTING AN IRON FRAME APPROX. SIZE 2X3

FEETS. IN WHICH WE ARE FIXING TWO WHEELS AS FIX IN OURVEHICLES AND THEN WE ADJOINS THOSE WHEEL WITH THE

HELP OF TIE RODE AND THEN TIE RODE IS CONNECTED WITH

STEERING RODE AS MENTION BELOW DIAGRAM.


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NOW WE ARE FIXING TWO DC MOTOR ATTECH WITH FRONT

LIGHT IN THE FRONT OF OUR FRAME AND MAKE THEM MOVING

WITH THE HELP OF MICROCHIP AND READ SWITCHS ATTECH

STEERING AND FRONT LIGHT DC MOTOR.

WE ARE ALSO USING SMALL ELECTRONIC MICROCHIP CIRCUIT

TO MAKE THIS MECHANICAL STRUCTURE AUTOMATED

WORKING.


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7. HOW OUR MODEL WORKS

IN THIS PROJECT WE HAVE FIVE DIFFERENT MOVING POSITION

OF THE FRONT LIGHT AS SHOWN BELOW.

1. POSITION 2-RIGHT

2. POSITION 1-RIGHT

3. POSITION 0-CENTRE

4. POSITION 1-LEFT

5. POSITION 2-LEFT


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WE ARE USING IR INTREPUTERSENSOR TO IDENTIFY THE

CURRENT POSITON OF FRONT LIGHT. THESE IR INTREPUTE

PROVIED PULSE TO THE MICROCHIP CIRCUIT AND MICROCHIP

CONTROL FRONT LIGHT FIXED DC MOTOR.

HOW IR INTREPUTER SENSOR WORKS

THESE IR INTREPUTERSENSOR WORK WHEN SOME

OBSTRUCTION CUT TRANSMITTER (TX) AND RECEIVER (RX)

SEE HOW IT WORKS

TX AND RX TRANSMITTING WAVE IN BETWEEN EACH OTHER

OBSTRUCTION CUT TO THE WAVE AND SENSOR GENRERATE

PULSE


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IR INTREPUTER SENSOR

NOW WE ARE USING THESE IR INTREPUTER SENSORIN OUR

MODEL TO MAKE MOVMENT AND IDENTIFED LIGHT POSITION,


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IR INTREPUTER SENSOR PLACEMENT

HOW THESE SENSOR PLACED IN

BETWEEN STEERING AND TIE

RODE


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WHEN STEERING MOVE, IT GIVE MOVEMENT TO TIE RODE.

WE FIX ONE INTRUPTER BAR WITH TIE RODE WHEEL.

WHEN WHEEL MOVES IT MOVE TO INTRUPTER BAR AND

INTRUPTER BAR SHOT TO IR INTREPUTER SENSORAS

MENTION ABOVE.

IR INTREPUTER SENSORGIVE PULSE TO THE ELECTRONIC

CIRCUIT AND CIRCUIT DRIVE THE FRONT LIGHT

AS MENTION BELOW


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FRONT LIGHT MOVEMENT


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APPROXIMATE COST

RS. 20000/-

CONCLUSIONSTHIS CAN BE VERY USEFUL SYSTEM IN OUR CAR WHEN WE ARE

CUTTING TO THE CAR RIGHT/LIFT FOR MORE FRONT CLEAR

VISIBLITY.

APPLICATIONSTHIS COULD BE IMPLEMENT IN OUR VECHICAL ESPICHIALLY IN

HEAVY CHEMIRCAL VECHIAL (TRUCK AND BUSES)


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USESIT PROVIDE LIGHT TO THE VECHIAL IN SHORT

TURNNING AND PROTECT FROM ACCIDENT

COMPONENTS USED1. STEERING

2. TIE RODE

3. TYRES

4. LIGHT

5. TWO MOTOR FOR MOVEMENT OF LIGHT

6. MODEL FRAME

7. SOME ELECTRONIC COMPONENTS AS PER REQUIRMENT RELAY

IR INTREPUTER SENSOR

MICROCHIP (AT89S52)

TRANSISTOR

CAPISITOR

RESISTANCE

DIODE

TRANSFORMER


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COMPONENT DETAIL

1.STEERING AND SUSPENSION

1. Tie Rod - Right

2. Tie Rod Socket - Right

3. Knuckle and Arm - Right

4. Steering Bell Crank

5. Steering Connecting Rod

6. Steering Gear Arm

7. Steering Gear Arm Assembly

8. Knuckle and Arm - Left

9. Tie Rod Socket - Left


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10.Tie Rod - Left

11.Socket Assembly

12.Steering Bell Crank Pin

13.Steering Bell Crank Cotter Pin

14.Steering Bell Crank Shaft

STEERING SYSTEMThe Steering System is illustrated in Fig. 30. It requires little attention

other than proper lubrication and maintaining correct alignment.

Alignment may be thrown out by striking curbs or other obstructions.

Looseness in the steering system will also affect alignment. It is impossible

to satisfactorily align front wheel without first adjusting the various

connections, including the front wheel bearings.

The correct toe-in of the front wheels is 3/64 3/32 which must be

accurately measured for satisfactory front tire wear and steering. The best

method of checking wheel alignment is by the use of the wheel alignmentdevice, which is available in most every well equipped shop.


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Periodic inspection and tightening of the steering parts will aid greatly in

maintaining alignment. Keep the steering connection rod and tie rod ball

joints snug; they must operate freely without lost motion. Keep the steering

gear arm No. 6 tight on the lever shaft and the steering housing bracket tight

on the frame. For adjustment of the front wheel bearings see the next

section, Front Wheel Bearings

1.

Housing Oil Seal

2. Lever Shaft Assembly

3. Housing Oil Filler Plug

4. Steering Column Clamp Assembly

5. Cam & Wheel Tube Assembly

6. Steering Column Oil Hole Cover

7. Horn Wire Contact Brush Assembly8. Steering Wheel

9. Steering Column Bearing Spring

10. Steering Column Bearing Spring Set

11. Steering Column Bearing Assembly


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2. 12. Steering Column & Bearing Assembly

13. Steering Wheel & Horn Button Nut

14. Horn Button

15. Horn Button Spring

16. Horn Button Spring Cup

17. Side Adjusting Screw

18. Housing Assembly

19. Cam Bearing Balls

20. Steering Gear Arm

21. Housing Bushing - Inner

22. Housing Bushing - Outer

The bell crank No. 4 is mounted on the frame front cross tube and swivels

on two needle bearings. The mounting shaft is removable from the frame

bracket by driving out a tapered locking pin. The bell crank tie-rod ball isreplaceable. Should the bell crank become bent or damaged, install a new

part.

Do not tighten the steering gear to dampen out steering trouble. Should

trouble develop, consult your Willys-Overland Dealer, as he has a definite

procedure for the inspection

and adjustment of the steering system.

FRONT WHEEL BEARINGSThe front wheels are mounted on two opposed tapered roll bearings. These

bearings are adjustable for wear and their satisfactory operation and long life

depends upon periodic attention and correct lubrication. Loose front wheel

bearings may cause excessive wear and will affect front wheel alignment. Ifthe bearing adjustment is too tight, the rollers may break or become

overheated.

To check the adjustment, first raise the front of the vehicle so that the tires

clear the floor. Check the brakes to be sure they are free and fully released.

With the hands, check sidewise shake of the wheel. If the bearings are


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correctly adjusted, shake of the wheel will be just perceptible and the wheel

will turn freely with no drag.

Should the test indicate that adjustment is necessary, remove the hub cap

axle shaft nut, washer, driving flange and shims. See Fig. 25. Wheel

bearing adjustment will then be accessible. Bend the lip of the nut locking

washer so that the adjustment lock nut and washer can be removed. Rotate

the wheel and tighten the adjusting nut until the wheel binds slightly. Then

back off the nut 1/6 turn, or more if necessary, making sure the wheel turns

freely without sidewise shake. Replace the locking washer and lock nut and

bend over the locking washer lip. Check the adjustment and reassemble the

driving flange, nut and hub cap, being sure to replace the shims.

REAR WHEEL BEARINGS

Each rear wheel is carried on a single tapered roller bearing which isadjusted by shims placed between the brake backing plate and the axle

flange.

Check wheel bearing adjustment in the same manner as the front wheel.

Should the check determine that adjustment is required, remove the hub cap;

remove the cotter pin, the axle shaft nut and use a wheel puller to remove the

wheel hub. Remove the bolts holding the brake dust shield, the grease and

bearing retainer and the brake assembly. Remove or install shims, Fig. 32,

No. 2 to adjust the bearing with .001" to .003" end float which will be just

perceptible when tested by hand. The shims available for this adjustment are

.003" - .005" and .030" thick.

Examine the grease retainer to be sure it is serviceable -- replace it if in

doubt, and reassemble.

MAINTENANCE OF WHEEL

BEARINGSWhen the vehicle is used for road work, lubricate

and adjust the front wheel bearings once each year;if used in dusty field work, twice each year.

The bearings should be given more than casual

cleaning. Use a clean stiff brush and suitable grease

solvent to remove all particles of old lubricant from

the bearings and hubs. After the bearings are


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thoroughly cleaned, inspect them for pitted races and rollers and check the

hub oil seals.

Repack the bearing cones and rollers and reassemble in the reverse order of

dismantling. Adjust them as directed in the preceding paragraphs.

Lubricate the rear wheel bearings sparingly. Oil forced from the oil relief

hole No. 1, Fig. 32, indicates when the bearing is amply lubricated.

Should it be necessary to adjust the bearings, clean them thoroughly and

repack them with the recommended lubricant.

MOUNTING AND DISMOUNTING WHEELSThe wheel mounting nuts and studs on both left wheels have left hand

threads to prevent them from being loosened by wheel action. The studs are

identified by an "L" stamped on the end. The left hand threaded nuts are

identified by a groove cut around the hexagonal faces. To remove the left

wheels, the nuts must be turned RIGHT, and to remove the right wheels,

turned to the LEFT.

TIRESThe recommended tire pressures are as follows:

6:00 x 16 Tires7:00 x 15 Tires

28-30 lbs.20-21 lbs.

The importance of correct tire inflation cannot be overemphasized. To

secure the maximum tire life and most efficient vehicle operation, it is

imperative that these pressures be maintained for all normal vehicle

operations.

Then the vehicle is used with driver only doing agricultural work on very

sandy or muddy soil, increased flotation and wheel traction may be secured

by decreasing the pressure of the 6:00 x 16 tire to 18 to 20 lbs., and the 7:00


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x 15 tire to 14 lbs. Should unusual operating conditions require this

reduction in pressure, use care that the tires are inflated to the recommended

pressure immediately when normal operation is resumed.

To secure maximum tire wear, the wheels should be switched at least twice

each year. The rear wheels should be moved to the opposite front positions

and the right front wheel moved straight back to the right rear position.

Place the spare on the left rear and use the left front as a spare.

To remove a tire from a drop centre rim, first deflate completely and then

force the tire away from the rim throughout the entire circumference until

the bead falls into the centre of the wheel rim, then with a heavy screw

driver or tire removing tool, used opposite the valve, remove one side of the

tire at a time and remove the inner tube.

Installation of a tire is made in the same manner by first dropping one side of

the tire into the centre of the rim and with a tire tool, spring the bead over

the wheel rim, using care not to damage the inner tube.

When mounting the wheel, alternately tighten opposite stud nuts to prevent

wheel wobble. After nuts have been tightened with the wheel jacked up,

lower the jack so wheel rests on the floor and retighten the nuts.

SPRINGS AND SHACKLESThe springs should be periodically examined for broken or shifted leaves,loose or missing rebound clips, angle of the spring shackles and the position

of the springs on the axle saddles. Springs with shifted leaves to not have

their normal strength. Missing rebound clips may permit the leaves to fan

out or break on rebound. Broken leaves may make the vehicle hard to

handle or permit the axle to shift out of line. Weakened springs may break

causing difficulty steering.

The front springs are interchangeable, as are the two rear.

The front ends of the front springs and the rear ends of the rear springs are

shackled, using "U" type shackles with threaded bushings. The rear ends of

the front springs and the front ends of the rear springs are bronze bushed and

pivoted on bolts in the shackles mounted on the frame.

The spring shackle threaded bushings use right and left hand threads,

depending upon where they are to be used. Six bushings are used with right


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hand threads and two with left hand threads. For identification the right

hand threaded type have plain hexagonal heads. The left hand have a groove

cut around the heads.

The two left hand threaded shackles can be identified by a small forged boss

on the lower shank of the shackle. They are used at the left front and the

right rear springs with the left hand threaded end down at the spring eyes.

The bushings are anchored solidly in the frame brackets and spring eyes and

the oscillation taken between the threads of the "U" shackle and the inner

threads of the bushings. The lubrication of the shackle bushings is very

important and should not be neglected, or excessive wear of the bushings

and "U" shackles will occur.

When making installation of a new "U" shackle or bushing, follow theprocedure below:

The shackles are installed with the bushing hexagon heads to the outside of

the frame. Install the shackle grease seal and retainer over the threaded end

of the shackle up to the shoulder. Insert the new shackle through the frame

bracket and the eye of the spring. Hold the "U" shackle tightly against the

frame bracket and start the upper bushing on the shackle, care being taken

when it enters the thread in the frame, that it is not cross-threaded. Screw

the bushings on the shackle about halfway, and then start the lower bushing,

hold the shackle tightly against the spring eye and thread this bushing abouthalfway, then alternating from top bushing to lower bushing, turn them in

until the head of the bushing is snug against the frame bracket and the

bushing in the spring eye is 1/32" away from the spring measured from the

inside of the hexagon head to the spring.

Lubricate the bushings with high pressure lubricant and then try the flex of

the shackle, which should be free. If the shackle is tight, it will cause spring

breakage and it will be necessary to rethread the bushings on the shackle.

SHOCK ABSORBERSThe shock absorbers are of the direct action type giving two-way control,

however they are not adjustable. They dampen spring action, as the vehicle

passes over irregularities in the road. The shock absorbers are mounted on

rubber bushings at both top and bottom. Should squeaks occur in the


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bushings, add a flat washer on the mounting pins to place the bushings under

greater pressure and prevent movement between the rubber and metal parts.

2. IR INTREPUTER SENSOR

PCB or Chassis Mount Photo Interrupter

This device enables you to turn off a circuit on and off optically. It consists

of an IR LED facing a phototransistor across and air gap. Any object in the

gap will interrupt the IR beam and consequently switch the phototransistor

on and off. The device is very fast and ideal for counting, timing or sensing

Block Measures 25Lx5Wx13H

Gap measure 3mm

Mounting Holes 3.2mm Dia


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Dc

motor


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DC GEAR MOTOR

Brand HOSIDEN motors (Japan)

R.P.M: 75-100

VOLT: 12-18V. DC

Dc motorMost electric motors work by electromagnetism, but motors based

on other electromechanical phenomena, such as electrostatic forcesand thepiezoelectric effect, also exist. The fundamental principle

upon which electromagnetic motors are based is that there is a

mechanical force on any current-carrying wire contained within a

magnetic field. The force is described by the Lorentz force law and

is perpendicular to both the wire and the magnetic field. Most

magnetic motors are rotary, but linear motors also exist. In a rotary

motor, the rotating part (usually on the inside) is called the rotor,

and the stationary part is called the stator. The rotor rotates becausethe wires and magnetic field are arranged so that a torque is

developed about the rotor's axis. The motor contains

electromagnets that are wound on a frame. Though this frame is

often called the armature, that term is often erroneously applied.

Correctly, the armature is that part of the motor across which the
http://en.wikipedia.org/wiki/Magnetismhttp://en.wikipedia.org/wiki/Electrostatic_motorhttp://en.wikipedia.org/wiki/Piezoelectric_effecthttp://en.wikipedia.org/wiki/Lorenz_forcehttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Linear_motorhttp://en.wikipedia.org/wiki/Rotorhttp://en.wikipedia.org/wiki/Statorhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Electromagnethttp://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Magnetismhttp://en.wikipedia.org/wiki/Electrostatic_motorhttp://en.wikipedia.org/wiki/Piezoelectric_effecthttp://en.wikipedia.org/wiki/Lorenz_forcehttp://en.wikipedia.org/wiki/Magnetic_fieldhttp://en.wikipedia.org/wiki/Linear_motorhttp://en.wikipedia.org/wiki/Rotorhttp://en.wikipedia.org/wiki/Statorhttp://en.wikipedia.org/wiki/Torquehttp://en.wikipedia.org/wiki/Electromagnethttp://en.wikipedia.org/wiki/Armature_(electrical_engineering)


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input voltage is supplied. Depending upon the design of the

machine, either the rotor or the stator can serve as the armature.

One of the first electromagnetic rotary motors was invented by

Michael Faraday in 1821 and consisted of a free-hanging wire

dipping into a pool ofmercury. A permanent magnet was placed in

the middle of the pool of mercury. When a current was passed

through the wire, the wire rotated around the magnet, showing that

the current gave rise to a circular magnetic field around the wire.

This motor is often demonstrated in school physics classes, but

brine(salt water) is sometimes used in place of the toxic mercury.

This is the simplest form of a class of electric motors called

homopolar motors. A later refinement is the Barlow's Wheel.

Another early electric motor design used a reciprocating plunger

inside a switched solenoid; conceptually it could be viewed as an

electromagnetic version of a two stroke internal combustion

engine.

The modern DC motor was invented by accident in 1873, whenZnobe Gramme connected a spinning dynamo to a second similar

unit, driving it as a motor.

The classic DC motor has a rotating armature in the form of an

electromagnet. A rotary switch called a commutatorreverses the

direction of the electric current twice every cycle, to flow through

the armature so that the poles of the electromagnet push and pull

against the permanent magnets on the outside of the motor. As the

poles of the armature electromagnet pass the poles of thepermanent magnets, the commutator reverses the polarity of the

armature electromagnet. During that instant of switching polarity,

inertia keeps the classical motor going in the proper direction. (See

the diagrams below.)
http://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/1821http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Magnethttp://en.wikipedia.org/wiki/Current_(electricity)http://en.wikipedia.org/wiki/Brinehttp://en.wikipedia.org/wiki/Homopolar_motorhttp://en.wikipedia.org/wiki/Barlow's_Wheelhttp://en.wikipedia.org/wiki/Solenoidhttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Z%C3%A9nobe_Grammehttp://en.wikipedia.org/wiki/Dynamohttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Commutator_(electric)http://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Inertiahttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Michael_Faradayhttp://en.wikipedia.org/wiki/1821http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Magnethttp://en.wikipedia.org/wiki/Current_(electricity)http://en.wikipedia.org/wiki/Brinehttp://en.wikipedia.org/wiki/Homopolar_motorhttp://en.wikipedia.org/wiki/Barlow's_Wheelhttp://en.wikipedia.org/wiki/Solenoidhttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Internal_combustion_enginehttp://en.wikipedia.org/wiki/Z%C3%A9nobe_Grammehttp://en.wikipedia.org/wiki/Dynamohttp://en.wikipedia.org/wiki/Direct_currenthttp://en.wikipedia.org/wiki/Commutator_(electric)http://en.wikipedia.org/wiki/Armature_(electrical_engineering)http://en.wikipedia.org/wiki/Inertia


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A simple DC electric motor. When the coil is powered, a magnetic

field is generated around the armature. The left side of the

armature is pushed away from the left magnet and drawn toward

the right, causing rotation.

The armature continues to rotate.

When the armature becomes horizontally aligned, the commutator

reverses the direction of current through the coil, reversing the

magnetic field. The process then repeats.
http://en.wikipedia.org/wiki/Image:Electric_motor_cycle_1.png


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ELECTRONIC COMPONENTS DETAIL

MICROCHIP - CONTROLLING IC AT89S52

INTRODUCTION

Security is the main problem of the homes, buildings, offices and industry

now days.

Hence we develop here an intelligent building system that monitor

continuously the parameters in different rooms in a building or differentapartment in industry and also control the problems arises in different

places.

The parameters the voltage and current signals by produced by sensors.

The signals are generated by temp. and light .controlling the devices if any

one the conditions of analog parameter exceed the limit.

BRIEF IDEA OF THE WORKING:

When there is dark in room 1 the lights will switched on. And if the lightintensity in the room crosses the higher limit then the lights switched of

accordingly. When the temp. of the room is less then 30c then the 1st AC will

switched on and if the temp. does not goes down

Then the second AC will also switch on but if the temp. goes down and

becomes less then 20c then the AC will off. The status of the temp. and

lights are monitor continuously and the switching of the AC and lights are


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according to it. The same function is applied on the second room. The temp.

of both rooms are displayed on the seven segment displays.

SCOPE OF THE PROJECT

This project can be the beneficial factor in the development of the buildings.

This application gives the basic idea in the architecture of the buildings like

what features should be their in a building for the safety of human life,

saving the energy and money.

As its name shows the can be used in the following:-

Houses

Companies

Factories

Schools and Colleges


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PREVIOUS WORK

The following steps I have taken to complete the project:.1. Complete study of the c 8051 and understand the programming

based on it.

2. Prepare the block diagram and the ckt. Diagram of the project and

clear up the working of the project .

3. Collect all the component and made-up the hardware model of it.

4. Write the software of it.

5. Test the hardware and software in different modes.


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A BRIEF INTRODUCTION TO

MICROCONTROLLER

Microcontrollers, as the name suggests, are small controllers. They are like

single chip computers that are often embedded into other systems to function

as processing/controlling unit. For example, the remote control you are using

probably has microcontrollers inside that do decoding and other controlling

functions. They are also used in automobiles, washing machines, microwave

ovens, toys ... etc, where automation is needed.

KEY FEATURES OF MICROCONTROLLERS:

HIGH INTEGRATION OF FUNCTIONALITY

Microcontrollers sometimes are called single-chip computers because they

have on-chip memory and I/O circuitry and other circuitries that enable them

to function as small standalone computers without other supporting circuitry.

FIELD PROGRAMMABILITY, FLEXIBILITY

Microcontrollers often use EEPROM or EPROM as their storage device toallow field programmability so they are flexible to use. Once the program is

tested to be correct then large quantities of microcontrollers can be

programmed to be used in embedded systems.


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EASY TO USE

Assembly language is often used in microcontrollers and since they usually

follow RISC architecture, the instruction set is small. The developmentpackage of microcontrollers often includes an assembler, a simulator, a

programmer to "burn" the chip and a demonstration board. Some packages

include a high-level language compiler such as a C compiler and more

sophisticated libraries.


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MICROCONTROLLER (AT89C51)

8051 microcontroller has 128 bytes of RAM, 4K bytes of on-chip ROM, twotimers, one serial port, and four ports (each 8-bits wide) all on a single chip.

The 8051 is an 8-bit processor i.e. the CPU can work on only 8 bits of data

at a time. The fixed amount of on-chip ROM, RAM, and number of I/O

ports in microcontroller makes them ideal for many applications in which

cost and space are critical.

The AT89C51 is a low-power, high-performance CMOS 8-bit

microcomputer with 4K bytes of Flash programmable and erasable read only

memory (PEROM). The on-chip Flash allows the program memory to bereprogrammed in-system or by a conventional nonvolatile memory

programmer. By combining a versatile 8-bit CPU with Flash on a monolithic

chip, the Atmel AT89C51 is a powerful microcomputer, which provides a

highly flexible and cost-effective solution to many embedded control

applications.

FEATURES:

Compatible with MCS-51 Products

4K Bytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-level Program Memory Lock

128 x 8-bit Internal RAM

32 Programmable I/O Lines

Two 16-bit Timer/Counters


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Six Interrupt Sources

Programmable Serial Channel

Low-power Idle and Power-down Modes

BLOCK DIAGRAM:

Int

err

up

t

contr

ol

Bu

sco

ntr

ol

Se

rial

p

or

E

T

C.Osc

C

P

U 4

I/O

Po

rts

On

-chi

p

RA

M

O

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chip

R

OM

fo

Timer 0

Timer 1

CounterIn

puts

P0 P1 P2 P3 TXD RXD

ADDRESS/DATA

External

Interrupt

s


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PIN CONFIGURATION:

PIN DESCRIPTION:

tpr

og

ram

co

de

1 40

2 39

3 38

4 37

5 36

6 35

7 34

8 33

9 32

10 31

11 30

12 29

13 28

14 27

15 26

16 25

17 24

18 23

19 22

20 21

P1.0

P1.1

P1.2

P1.3

P1.4

P1.5

P1.6

P1.7

RST

(RXD) P3.0

(TXD) P3.1

(INT0) P3.2

(INT1) P3.3

(T0) P3.4

(T1) P3.5

(WR) P3.6

(RD) P3.7

XTAL2

XTAL1

GND

Vcc

P0.0 (AD0)

P0.1 (AD1)

P0.2 (AD2)

P0.3 (AD3)

P0.4 (AD4)

P0.5 (AD5)

P0.6 (AD6)

P0.7 (AD7)

EA/VPP

ALE/PROG

PSEN

P2.7 (A15)

P2.6 (A14)

P2.5 (A13)

P2.4 (A12)

P2.3 (A11)

P2.2 (A10)

P2.1 (A9)

P2.0 (A8)


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PIN DESCRIPSION:

VCC - Supply voltage.

GND - Ground.

Port 0 - Port 0 is an 8-bit open-drain bi-directional I/O port. As an output

port, each pin can sink eight TTL inputs. When 1s are written to port 0 pins,

the pins can be used as high-impedance inputs.

Port 0 may also be configured to be the multiplexed low-order address/data

bus during accesses to external program and data memory. In this mode P0

has internal pull-ups.

Port 0 also receives the code bytes during Flash programming, and outputs

the code bytes during program verification. External pull-ups are required

during program verification.

Port 1 - Port 1 is an 8-bit bi-directional I/O port with internal pull-ups.

The Port 1 output buffers can sink/source four TTL inputs. When 1s are

written to Port 1 pins they are pulled high by the internal pull-ups and can be

used as inputs. As inputs, Port 1 pins that are externally being pulled lowwill source current (IIL) because of the internal pull-ups. Port 1 also receives

the low-order address bytes during Flash programming and verification.

Port 2 - Port 2 is an 8-bit bi-directional I/O port with internal pull-ups.

The Port 2 output buffers can sink/source four TTL inputs.

When 1s are written to Port 2 pins they are pulled high by the internal pull-

ups and can be used as inputs. As inputs, Port 2 pins that are externally

being pulled low will source current (IIL) because of the internal pull-ups.

Port 2 emits the high-order address byte during fetches from external

program memory and during accesses to external data memory that use 16-bit addresses (MOVX @ DPTR). In this application, it uses strong internal

pull-ups when emitting 1s. During accesses to external data memory that use

8-bit addresses (MOVX @ RI), Port 2 emits the contents of the P2 Special

Function Register.


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Port 2 also receives the high-order address bits and some control signals

during Flash programming and verification.

Port 3 - Port 3 is an 8-bit bi-directional I/O port with internal pullups.

The Port 3 output buffers can sink/source four TTL inputs. When 1s are

written to Port 3 pins they are pulled high by the internal pullups and can be

used as inputs. As inputs, Port 3 pins that are externally being pulled low

will source current (IIL) because of the pullups. Port 3 also serves the

functions of various special features of the AT89C51 as listed below:

RST - Reset input. A high on this pin for two machine cycles while the

oscillator is running resets the device.

ALE/PROG - Address Latch Enable output pulse for latching the low byte

of the address during accesses to external memory. This pin is also theprogram pulse input (PROG) during Flash programming.

PORT PIN ALTERNATE FUNCTIONS

P3.0 RXD (serial input port)

P3.1 TXD (serial output port)

P3.2 INT0 (external interrupt 0)P3.3 INT1 (external interrupt 1)

P3.4 T0 (timer 0 external input)

P3.5 T1 (timer 1 external input)

P3.6 WR (external data memory write strobe)

P3.7 RD (external data memory read strobe)


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In normal operation ALE is emitted at a constant rate of 1/6 the oscillator

frequency, and may be used for external timing or clocking purposes. Note,

however, that one ALE pulse is skipped during each access to external Data

Memory.

If desired, ALE operation can be disabled by setting bit 0 of SFR location

8EH. With the bit set, ALE is active only during a MOVX or MOVC

instruction. Otherwise, the pin is weakly pulled high. Setting the ALE-

disable bit has no effect if the microcontroller is in external execution mode.

PSEN - Program Store Enable is the read strobe to external program

memory. When the AT89C51 is executing code from external program

memory, PSEN is activated twice each machine cycle, except that two PSEN

activations are skipped during each access to external data memory.

EA/VPP - External Access Enable. EA must be strapped to GND in order to

enable the device to fetch code from external program memory locations

starting at 0000H up to FFFFH. Note, however, that if lock bit 1 is

programmed, EA will be internally latched on reset.

EA should be strapped to VCC for internal program executions.

This pin also receives the 12-volt programming enable voltage (VPP) during

Flash programming, for parts that require 12-volt VPP.

XTAL1 - Input to the inverting oscillator amplifier and input to the internal

clock operating circuit.

XTAL2 - Output from the inverting oscillator amplifier.


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OSCILLATOR CHARACTERISTICS:

XTAL1 and XTAL2 are the input and output, respectively, of an inverting

amplifier, which can be configured for use as an on-chip oscillator. Either aquartz crystal or ceramic resonator may be used. To drive the device from an

external clock source, XTAL2 should be left unconnected while XTAL1 is

driven.

Figure 1. Oscillator Connections

Note: C1, C2 = 30 pF +/- 10 pF for Crystals

= 40 pF +/- 10 pF for Ceramic Resonators

There are no requirements on the duty cycle of the external clock signal,

since the input to the internal clocking circuitry is through a divide-by-two

flip-flop, but minimum and maximum voltage high and low time

specifications must be observed.

XTAL1

XTAL2

C1

C2

GND


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THE 8051 REGISTERS:

The most widely used registers of the 8051 are A (accumulator), B, R0, R1,

R2, R3, R4, R5, R6, R7, DPTR (data pointer), and PC (program counter).All of the above registers are 8-bits, except DPTR and the program counter.

The 8 bots of a register are shown below from the MSB (most significant

bit) D7 to the LSB (least significant bit) D0.

D7 D6 D5 D4 D3 D2 D1 D0

PROGRAM COUNTER:

The program counter points to the address of the next instruction to beexecuted. As the CPU fetches the opcode from the program ROM, the

program counter is incremented to point to the next instruction. The PC is 16

bits wide i.e. it can access program addresses 0000 to FFFFH, a total of 64K

bytes of code.

PSW (PROGRAM STATUS WORD) REGISTER

The PSW contains status bits that reflect the current state of the CPU and isalso called flag register. The PSW contains the Carry bit, the Auxiliary

Carry bit, the two register bank select bits, the overflow flag bit, a parity bit,

and two user definable status flags.

CY PSW.7 Carry flag.

AC PSW.6 Auxiliary carry flag.

--- PSW.5 Available to the user for general purpose.

RS1 PSW.4 Register Bank selector bit 1.

RS0 PSW.3 Register Bank selector bit 0.

OV PSW.2 Overflow flag.

--- PSW.1 User definable bit.

P PSW.0 Parity flag.

CY AC F0 RS1 RS0 OV --- P


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RS1 RS0 REGISTER BANK ADDRESS

0 0 0 00H 07H

0 1 1 08H 0FH

1 0 2 10H 17H

1 1 3 18H 1FH

CY, THE CARRY FLAG

This flag is set whenever there is a carry out from the D7 bit. This flag bit is

affected after an 8-bit addition or subtraction. It can also be set to

1 or 0 directly by an instruction such as SETB C and CLR C where

SETB C stands for set bit carry and CLR C for clear carry.

AC, THE AUXILIARY CARRY FLAG

If there is a carry from D3 to D4 during an ADD or SUB operation, this bit

is set; otherwise, it is cleared. This flag is used by instructions that perform

BCD (binary coded decimal) arithmetic.

P, THE PARITY FLAG

The parity flag reflects the number of 1s in the A (accumulator) register

only. If the A register contains an odd number of 1s, then P=1. Therefore,

P=0 if A has an even number of 1s.

OV, THE OVERFLOW FLAG

This flag is set whenever the result of a signed number operation is too large,causing the high-order bit to overflow into the sign bit.

RAM MEMORY SPACE ALLOCATION IN THE 8051

There are 128 bytes of RAM in the 8051, which are assigned addresses 00 to

7FH. These 128 bytes are divided into three different groups:


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1. A total of 32 bytes from locations 00 to 1H hex are set aside for

register banks and the stack.

2. A total of 16 bytes from locations 20H to 2FH are set aside for bit-

addressable read/write memory.

3. A total of 80 bytes from locations 30H to 7FH are used for read and

write storage, or what is normally called a scratch pad. These

80 locations of RAM are widely used for the purpose of storing data

and parameters by 8051 programmers.

7F

Scratch pad RAM

30

2F

Bit-Addressable RAM

20

1F Register Bank 3

18

17 Register Bank 2

10

0FRegister Bank 1 (stack)

08

07

Register Bank 0

00REGISTER BANKS IN THE 8051

The 32 bytes of RAM which is set aside for the register banks and stack is

divided into 4 banks of registers in which each bank has 8 registers, R0

R7. RAM locations from 0 to 7 are set aside for bank 0 of R0 R7


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where R0 is RAM location 0, R1 is RAM location 1, R2 is location 2, and so

on, until memory location 7 which belongs to R7 of bank 0. The second

bank of registers R0 R7 starts at RAM location 08 and goes to location

0FH. The third bank of R0 R7 starts at memory location 10H and goes to

location 17H; and finally RAM locations 18H to 1FH are set aside for the

fourth bank of R0 R7. The following tables shows how the 32 bytes are

allocated into 4 banks:

Bank 0 Bank 1 Bank 2 Bank 3

STACK IN THE 8051

The stack is a section of RAM used by the CPU to store information

temporarily. This information could be data or an address. The CPU needs

this storage area since there are only a limited number of registers. The

register used to access the stack is called the SP (stack pointer) register. The

R7 7

R6 6

R5 5

R4 4

R3 3

R2 2

R1 1

R0 0

R7 7

R6 6

R5 5

R4 4

R3 3

R2 2

R1 1

R0 0

R7 7

R6 6

R5 5

R4 4

R3 3

R2 2

R1 1

R0 0

R7 7

R6 6

R5 5

R4 4

R3 3

R2

R12 1

R0 0


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stack pointer in the 8051 is only 8 bits wide i.e. it can take values of 00 to

FFH. When the 8051 is powered up, the SP

register contains value 07 which implies that RAM location 08 is the first

location being used for the stack by the 8051. The storing of a CPU register

in the stack is called a PUSH, and loading the contents of the stack back into

a CPU register is called a POP. In other words, a register is pushed onto the

stack to save it and popped off the stack to retrieve it.

PUSHING ONTO THE STACK:

In the 8051 the stack pointer (SP) is pointing to the last used location of the

stack. As data is pushed onto the stack, the stack pointer (SP) is incremented

by one and the contents of the register are saved on the stack. To push the

registers onto the stack, RAM addresses are used.

POPPING FROM THE STACK:

Popping the contents of the stack back into a given register is the opposite

process of pushing. With every pop, the top byte of the stack is copied to the

register specified by the instruction and the stack pointer is decremented

once.

ADDRESSING MODES:

The addressing modes in the microcontroller instruction set are as follows:

1. DIRECT ADDRESSING

In direct addressing, the operand is specified by an 8-bit address field in the

instruction. Only internal RAM and SFRs cab be directly accessed.

2. INDIRECT ADDRESSING

In indirect addressing, the instruction specifies a register that specifies a

register that contains the address of the operand. Both internal and external

RAM can be indirectly accessed.


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The address register for 8-bit addresses can be either the stack pointer or R0

or R1 of the selected register bank. The address register for 16-bit addresses

can be only the 16-bit data pointer register, DPTR.

3. REGISTER INSTRUCTIONS

The register banks, which contain registers R0 through R7, can be accessed

by instructions whose opcodes carry a 3-bit register specification.

Instructions that access the registers this way make efficient use of code,

since this mode eliminates an address byte. When the instruction is

executed, one of the eight registers in the selected bank is accessed. One of

four banks is selected at execution time by the two bank select bits in the

PSW.

4. REGISTER-SPECIFIC INSTRUCTIONS

Some instructions are specific to a certain register. For example, some

instructions always operate on the Accumulator, so no address byte is

needed to point to it. In these cases, the opcode itself points to the correct

register.

5. IMMEDIATE CONSTANTS

The value of a constant can follow the opcode in program memory. For

example,

MOV A, #100

Loads the Accumulator with the decimal number 100. The same number

could be specified in hex digits as 64H.

6. INDEXED ADDRESSING

Program memory can only be accessed via indexed addressing. This

addressing mode is intended for reading look-up labels in program memory.

A 16-bit base register (either DPTR or the Program Counter) points to the

base of the table, and the accumulator is set up with the table entry number.


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The address of the table entry in program memory is formed by adding the

accumulator data to the base pointer.

8051 INSTRUCTION SET

MNEMONIC:

The MNEMONIC column contains the 8051 Instruction Set Mnemonic and

a brief description of the instruction's operation.

OPERATION:

The OPERATION column describes the 8051 Instruction Set in

unambiguous symbology. Following are the definitions of the symbols usedin this column.

Bits of a register inclusive. For example, PC means bits

0 through 10 inclusive of the PC. Bit 0 is always the

least significant bit.

+ Binary addition

- Binary 2s complement subtraction

/ Unsigned integer division

X Unsigned integer multiplication

~ Binary complement (1s complement)

^ Logical And

v Inclusive Or

v Exclusive Or

> Greater than

Not equal to

= Equals

-> Is written into. For example, A + SOper -> A means the

result of the binary addition between A and the Source

Operand is written into A.

A The 8-bit Accumulator Register.

AC The Auxiliary Carry Flag in the Program Status Word

CF The Carry Flag in the Program Status Word

DoperThe Destination Operand used in the instruction.


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This column gives the machine language hexadecimal opcode for each 8051

instruction.

BYTE:

This column gives the number of bytes in each 8051 instruction.

CYC:

This column gives the number of cycles of each 8051 instruction. The time

value of a cycle is defined as 12 divided by the oscillator frequency. For

example, if running an 8051 family component at 12 MHz, each cycle takes

1 microsecond.


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POWER SUPPLY

Most of the digital circuits operate on 5 volt DC supply which isobtained by the following circuit. The power supply circuit consists ofa step down transformer, bridge rectifier and 7805 voltage regulatorIC.

BRIDGE RECTIFIERS

Bridge rectifier circuit consists of four diodes arranged in the form of a

bridge as shown in figure.

OPERATION:

AC Supply

D1

D2

D3

D4

1

B 2

A

3 4

7805

1000 F + +

--

5 V

DC


52/65

During the positive half cycle of the input supply, the upper end A of the

transformer secondary becomes positive with respect to its lower point B.

This makes Point1 of bridge positive with respect to point2. the diode D1 &

D2 become forward biased & D3 & D4 become reverse biased. As a result a

current starts flowing from point1, through D1 the load & D2 to the

negative end.

During negative half cycle, the point2 becomes positive with respect to

point1. Diode D1 & D2 now become reverse biased. Thus a current flow

from point 2 to point1.

TRANSFORMER:

Transformers are a major class of coils having two or more windings usually

wrapped around a common core made from laminated iron sheets.

It has two coils named primary & secondary. If the current flowing through

primary is fluctuating, then a current will be induced into the secondary

winding. A steady current will not be transferred from one coil to other coil.

Transformers are of two types:

1. Step up transformer

2. Step down transformer

AC

Supply Load+ -

D1

D2

D3

D4

1

B 2

A

3 4


53/65

In power supply we use step down transformer. We apply 220V AC on the

primary of step down transformer. This transformer steps down this voltage

to 9V AC. We give this 9 V AC to rectifier circuit, which convert it to 5V

DC.

REGULATOR:

7805 IC is used as regulator in 5V power supply.

IN 7805 pin no.1 is input pin through which non-regulated signal is applied.

Pin no.3 is grounded & the regulated output is taken from pin no.2.

7805

1 3 2

1 - IN2 - OUT

3 - GND


54/65

RELAYS

It is often desirable or essential to isolate one circuit electrically from

another, while still allowing the first circuit to control the second.

For example, if you wanted to control a high-voltage circuit from your

computer, you would probably not want to connect it directly to the a low-

voltage port on the back of your computer in case something went wrongand the mains electricity ended up destroying the expensive parts inside your

computer.

One simple method of providing electrical isolation between two circuits is

to place a relay between them, as shown in the circuit diagram of figure 1. A

relay consists of a coil that may be energized by the low-voltage circuit and

one or more sets of switch contacts, which may be connected to the high-

voltage circuit.

How Relays Work

In figure 2a the relay is off. The metal arm is at its rest position and so there

is contact between the Normally Closed (N.C.) switch contact and the

'common' switch contact.


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If a current is passed through the coil, the resulting magnetic field attracts

the metal arm and there is now contact between the Normally Open (N.O.)

switch contact and the common switch contact, as shown in figure 2b.

Advantages of Relays

The complete electrical isolation improves safety by ensuring that

high voltages and currents cannot appear where they should not be.

Relays come in all shapes and sizes for different applications and they

have various switch contact configurations. Double Pole Double

Throw (DPDT) relays are common and even 4-pole types are

available. You can therefore control several circuits with one relay oruse one relay to control the direction of a motor.

It is easy to tell when a relay is operating - you can hear a click as the

relay switches on and off and you can sometimes see the contacts

moving.

Disadvantages of Relays

Being mechanical though, relays do have some disadvantages over othermethods of electrical isolation:

Their parts can wear out as the switch contacts become dirty - high

voltages and currents cause sparks between the contacts.

They cannot be switched on and off at high speeds because they have

a slow response and the switch contacts will rapidly wear out due to

the sparking.


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Their coils need a fairly high current to energise, which means some

micro-electronic circuits can't drive them directly without additional

circuitry.

The back-emf created when the relay coil switches off can damage the

components that are driving the coil. To avoid this, a diode can beplaced across the relay coil, as will be seen in anyElectronics in

Meccano circuits that use relays with sensitive components.

Choosing a Relay

When choosing a relay to use in a circuit, you need to bear in mind

properties of both the coil and the switch contacts. Firstly, you will need to

find a relay that has the required number of switch poles for your

application. You then need to make sure that the switch contacts can copewith the voltage and current you intend to use - for example, if you were

using the relay to switch a 60W mains lamp on and off, the switch contacts

would need to be rated for at least 250mA at 240V AC (or whatever the

mains voltage is in your country).

Also of importance is the material that the switch contacts are made of - gold

is good for low-voltages, whereas tungsten is suitable for switching high

voltages and currents.

Finally, you need to choose a relay that has a coil that can be energised byyour low-voltage control circuit. Relay coils are generally rated by their

voltage and resistance, so you can work out their current consumption using

Ohm's Law. You will need to make sure that the circuit powering the coil

can supply enough current, otherwise the relay will not operate properly.

The Latching Relay Circuit

If a relay is connected as shown in figure 3, it will become 'latched' on when

the coil is energised by pressing the Trigger button. The only way to turn the

relay off will then be to cut the power supply by pressing the Reset button(which must be a push-to-break type).


57/65

The technical name for this type of behaviour is 'bistable', since the circuit

has two stable states for its output - on and off. Bistable circuits can also be

constructed using many other components, including the 555 timer IC and

transistors.

What's the point of this circuit? The Normally Open switch contact of the

relay could also be connected to a device such as a motor, as shown by the

dotted connections in figure 3. The device will then run indefinitely untilsome event (maybe triggered by the device) momentarily presses the Reset

button, thereby turning off the coil ready for the Trigger button to be pressed

again.

This system could be used in a model which needs a 'Push to Operate'

button. A motor and gearing system in the model can be used to press the

Reset button to cut the power to the relay coil after the model has been

running for a certain amount of time, or until a certain event has occurred.

Of course, you would have to be sure that there was enough momentum in

the mechanism that the button is released ready for the next cycle.

CAPACITORS


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It is an electronic component whose function is to accumulate charges

and then release it.

To understand the concept of capacitance, consider a pair of metal

plates which all are placed near to each other without touching. If a

battery is connected to these plates the positive pole to one and the

negative pole to the other, electrons from the battery will be attracted

from the plate connected to the positive terminal of the battery. If the

battery is then disconnected, one plate will be left with an excess of

electrons, the other with a shortage, and a potential or voltage

difference will exists between them. These plates will be acting as

capacitors. Capacitors are of two types: - (1) fixed type like ceramic,

polyester, electrolytic capacitors-these names refer to the material they

are made of aluminium foil. (2) Variable type like gang condenser inradio or trimmer. In fixed type capacitors, it has two leads and its value

is written over its body and variable type has three leads. Unit of

measurement of a capacitor is farad denoted by the symbol F. It is a

very big unit of capacitance. Small unit capacitor are pico-farad

denoted by pf (Ipf=1/1000,000,000,000 f) Above all, in case of

electrolytic capacitors, it's two terminal are marked as (-) and (+) so

check it while using capacitors in the circuit in right direction. Mistake

can destroy the capacitor

or entire circuit in

operational.

DIODE


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The simplest semiconductor device is made up of a sandwich of P-

type semi conducting material, with contacts provided to connect the p-

and n-type layers to an external circuit. This is a junction Diode. If the

positive terminal of the battery is connected to the p-type material

(cathode) and the negative terminal to the N-type material (Anode), a

large current will flow. This is called forward current or forward

biased.

If the connections are reversed, a very little current will flow. This is

because under this condition, the p-type material will accept the electrons

from the negative terminal of the battery and the N-type material will give

up its free electrons to the battery, resulting in the state of electrical

equilibrium since the N-type material has no more electrons. Thus there will

be a small current to flow and the diode is called Reverse biased.

Thus the Diode allows direct current to pass only in one direction

while blocking it in the other direction. Power diodes are used in concerting

AC into DC. In this, current will flow freely during the first half cycle

(forward biased) and practically not at all during the other half cycle (reverse

biased). This makes the diode an effective rectifier, which convert ac into

pulsating dc. Signal diodes are used in radio circuits for detection. Zener

diodes are used in the circuit to control the voltage.

Some common diodes are:-

1. Zener diode.

2. Photo diode.

3. Light Emitting diode.

1. ZENER DIODE:-


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A zener diode is specially designed junction diode, which can operate

continuously without being damaged in the region of reverse break down

voltage. One of the most important applications of zener diode is the design

of constant voltage power supply. The zener diode is joined in reverse bias

to d.c. through a resistance R of suitable value.

2. PHOTO DIODE:-

A photo diode is a junction diode made from photo- sensitive

semiconductor or material. In such a diode, there is a provision to allow the

light of suitable frequency to fall on the p-n junction. It is reverse biased, but

the voltage applied is less than the break down voltage. As the intensity of

incident light is increased, current goes on increasing till it becomes

maximum. The maximum current is called saturation current.

3. LIGHT EMITTING DIODE (LED):-

When a junction diode is forward biased, energy is released at the

junction diode is forward biased, energy is released at the junction due to

recombination of electrons and holes. In case of silicon and germanium

diodes, the energy released is in infrared region. In the junction diode made

of gallium arsenate or indium phosphide, the energy is released in visible

region. Such a junction diode is called a light emitting diode or LED.

RESISTANCE

Resistance is the opposition of a material to the current. It is measured

in Ohms ( ). All conductors represent a certain amount of resistance, since

no conductor is 100% efficient. To control the electron flow (current) in a

predictable manner, we use resistors. Electronic circuits use calibrated

lumped resistance to control the flow of current. Broadly speaking, resistor


61/65

can be divided into two groups viz. fixed & adjustable (variable) resistors. In

fixed resistors, the value is fixed & cannot be varied. In variable resistors,

the resistance value can be varied by an adjuster knob. It can be divided into

(a) Carbon composition (b) Wire wound (c) Special type. The most common

type of resistors used in our projects is carbon type. The resistance value is

normally indicated by colour bands. Each resistance has four colours, one of

the band on either side will be gold or silver, this is called fourth band and

indicates the tolerance, others three band will give the value of resistance

(see table). For example if a resistor has the following marking on it say red,

violet, gold. Comparing these coloured rings with the colour code, its value

is 27000 ohms or 27 kilo ohms and its tolerance is 5%. Resistor comes in

various sizes (Power rating). The bigger, the size, the more power rating of

1/4 watts. The four colour rings on its body tells us the value of resistor

value as given below.

COLOURS CODE

Black--------------------------------------------0

Brown-------------------------------------------1

Red----------------------------------------------2

Orange------------------------------------------3

Yellow------------------------------------------4

Green--------------------------------------------5Blue----------------------------------------------6

Violet--------------------------------------------7

Grey---------------------------------------------8

White--------------------------------------------9

The first rings give the first digit. The second ring gives the seconddigit. The third ring indicates the number of zeroes to be placed after the

digits. The fourth ring gives tolerance (gold 5%, silver 10%, No colour

20%).


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In variable resistors, we have the dial type of resistance boxes. There

is a knob with a metal pointer. This presses over brass pieces placed along a

circle with some space b/w each of them.

Resistance coils of different values are connected b/w the gaps. When

the knob is rotated, the pointer also moves over the brass pieces. If a gap is

skipped over, its resistance is included in the circuit. If two gaps are skipped

over, the resistances of both together are included in the circuit and so on.

A dial type of resistance box contains many dials depending upon the

range, which it has to cover. If a resistance box has to read upto 10,000 , it

will have three dials each having ten gaps i.e. ten resistance coils each of

resistance 10 . The third dial will have ten resistances each of 100 .

The dial type of resistance boxes is better because the contactresistance in this case is small & constant.

TRANSISTOR

The name is transistor derived from transfer resistors indicating a

solid state Semiconductor device. In addition to conductor and insulators,there is a third class of material that exhibits proportion of both. Under some

conditions, it acts as an insulator, and under other conditions its a

conductor. This phenomenon is called Semi-conducting and allows a

variable control over electron flow. So, the transistor is semi conductor

device used in electronics for amplitude. Transistor has three terminals, one

is the collector, one is the base and other is the emitter, (each lead must be

connected in the circuit correctly and only then the transistor will function).

Electrons are emitted via one terminal and collected on another terminal,

while the third terminal acts as a control element. Each transistor has a

number marked on its body. Every number has its own specifications.

There are mainly two types of transistor (i) NPN & (ii) PNP

NPN Transistors:


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When a positive voltage is applied to the base, the transistor begins to

conduct by allowing current to flow through the collector to emitter circuit.

The relatively small current flowing through the base circuit causes a much

greater current to pass through the emitter / collector circuit. The

phenomenon is called current gain and it is measure in beta.

PNP Transistor:

It also does exactly same thing as above except that it has a negative

voltage on its collector and a positive voltage on its emitter.

Transistor is a combination of semi-conductor elements allowing a

controlled current flow. Germanium and Silicon is the two semi-conductor

elements used for making it. There are two types of transistors such asPOINT CONTACT and JUNCTION TRANSISTORS. Point contact

construction is defective so is now out of use. Junction triode transistors are

in many respects analogous to triode electron tube.

A junction transistor can function as an amplifier or oscillator as can a

triode tube, but has the additional advantage of long life, small size,

ruggedness and absence of cathode heating power.

Junction transistors are of two types which can be obtained while

manufacturing.

The two types are: -

1) PNP TYPE:This is formed by joining a layer of P type of

germanium to an N-P Junction

NP


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2) NPN TYPE:This is formed by joining a layer of N type germanium

to a P-N Junction.

Both types are shown in figure, with their

symbols for representation. The centre section is

called the base, one of the outside sections-the

emitter and the other outside section-the collector. The direction of the

arrowhead gives the direction of the conventional current with the forward

bias on the emitter. The conventional flow is opposite in direction to the

electron flow.

OPERATION OF PNP TRANSISTOR:-

A PNP transistor is made by sand witching two PN germanium or

silicon diodes, placed back to back. The centre of N-type portion is

extremely thin in comparison to P region. The P region of the left is

connected to the positive terminal and N-region to the negative terminal i.e.

PN is biased in the forward direction while P region of right is biased

negatively i.e. in the reverse direction as shown in Fig. The P region in the

forward biased circuit is called the emitter and P region on the right, biasednegatively is called collector. The centre is called base.

The majority carriers (holes) of P region (known as emitter) move to

N region as they are repelled by the positive terminal of battery while the

electrons of N region are attracted by the positive terminal. The holes

overcome the barrier and cross the emitter junction into N region. As the

width of base region is extremely thin, two to five percent of holes

recombine with the free electrons of N-region which result in a small basecurrent while the remaining holes (95% to 98%) reach the collector junction.

The collector is biased negatively and the negative collector voltage aids in

sweeping the hole into collector region.

As the P region at the right is biased negatively, a very small current

should flow but the following facts are observed:-

N P N


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1) A substantial current flows through it when the emitter junction is biased

in a forward direction.

2) The current flowing across the collector is slightly less than that of the emitter,and

3) The collector current is a function of emitter current i.e. with the

decrease or increase in the emitter current a corresponding

change in the collector current is observed.

The facts can be explained as follows:-

1. As already discussed that 2 to 5% of the holes are lost in recombination with the

electron n base region, which result in a small base current and hence the collector

current is slightly less than the emitter current.

2. The collector current increases as the holes reaching the collector

junction are attracted by negative potential applied to the collector.

3. When the emitter current increases, most holes are injected into the

base region, which is attracted by the negative potential of the collector

and hence results in increasing the collector current. In this way emitter

is analogous to the control of plate current by small grid voltage in a

vacuum triode.

Hence we can say that when the emitter is forward biased and collector

is negatively biased, a substantial current flows in both the circuits. Since a

small emitter voltage of about 0.1 to 0.5 volts permits the flow of an

appreciable emitter current the input power is very small. The collector voltagecan be as high as 45 volts.

car light control-final

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