MARATHWADA INSTITUTE OF TECHNOLOGY BULANDSHAHR

Project report “ Anti theft and auto braking car”

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AbstractSeveral objectives can be accomplished with the Optical Voice Link: An instructor may

use it as a short, hands-on fiber optic curriculum or as a module to demonstrate before

the class. A student may use the kit for a science project; hobbyists can use it as a home

or industrial project to amaze their friends. Experience and while working with the

electronic microphone, analog fiber optic transmitter and receiver, and the fiber cable

interfaces. You will hear your own voice, for example, after it has been converted into,

through and out of an optical fiber.

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Table of content

Title Page no Certificate 1 Abstract 2 Aknowledgement 3Table of content 4 1.Introduction 1 2.Component 2 3.Description of steppermotor 3

1)Steppermotor introduction 32 steppermotor type 4i)variable reluctance 4ii)permanent magnent 4iii)Hybrid 5iv)industrial application of stepper motor 6v) Dc motor vs stepper motor 13

4) Discription of breaking coil 14i)Introduction of breaking system 14

5) Discription of 555 timer ic 17i)Timer operation 17ii) Astable 555 operation 18

6) Description of different types of relay 20i) relay 20ii) relay operation 22

7)Description of ir transmitter and receiver circuit 24 i)Photo diode 25 ii)reverse biase diode circut 25

8)Discription of gears 28i)types of grear 28 a)spur gear 28 b)Helical gear 29 c)Bevel gear 29 d)worm gear 30e) Crown gear 30

9) Description of resistance 31i) Resistance 31ii) Color code 32

10) Description of capacitance 34i) capacitors 34

11) working of soldering 35i) Mounting and soldering 35ii)The soldering kit 36

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12) Circuit design 3913) Application 4214) Conclusion 4315) Reference 44

INTRODUCTION

In this project an automobile hybrid vehicle model is used to run the prototype in

practical manner. The IR sensing circuit comprises a 555 timer and relay switching

actually sense the obstruction comes in front of it. The circuit activates the relay

connected to it and it switches the hybrid vehicle DC motor off that provides the power to

move. On the other end, another relay switching energize the Induction braking

mechanism that shorts the circuit around the stepper motor pins and it stops the shaft of

the vehicle momentarily. Thus the IR circuit provides two relay switches for both

solutions for brake.

BLOCK DIAGRAM

BLOCK DIAGRAM

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555 TimersBasedtr. /rec.

With relay activation

Relay

Relay

Induction Breaking Coil

Gear Attachment

T

R

STEPPERMOTOR

Rear Wheels

COMPONENTS USED IN CAR

1. Stepper motor.

2. Induction braking coil.

3. 555 timers IC.

4. Relays.

5. IR transmitter.

6. IR receiver.

7. Gears.

8. Resistances.

9. Capacitors.

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DESCRIPTION OF STEPPER MOTOR

STEPPER MOTOR

INTRODUCTION: -

A stepper motor is a brushless motor whose rotor rotates in discrete angular movements

when its stator windings are energized in a programmed manner. Rotation occurs because

of magnetic interaction between rotor poles and poles of sequentially energized stator

windings. The rotor has no electrical windings, but has salient and magnetized poles.

The input given to the motor is in the form of electrical pulses. For every input pulse the

motor shaft turns through a specified number of degrees called a step. The name stepping

given to this motor is based on its working principle i.e. one step rotation for one input

pulse. The range of step size may vary from 0.720 to 900. Actually a stepper motor can

be regarded as a digital electromechanical device, which translates input digital

information in form of electric pulses into discrete steps of shaft rotation. In position

control system if the number of input pulses sent to the motor is known, the actual

position of driven job can be obtained. Thus a digital position control system employing a

stepper motor needs no rotor position sensors and an expensive feedback loop.

A stepping motor differs from a conventional motor as under:-

Input to stepper motor is in form of electric pulses whereas input a conventional

motor is invariably from a constant voltage source.

A conventional motor has a free running shaft whereas shaft of stepper motor moves

through angular steps.

In control system applications, no feedback loop is required when stepper motor is

used but a feedback loop is required when conventional motor is used.

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A stepper motor is digital electromechanical device whereas a conventional motor is

an electromechanical device. Stepper motors may be divided into following groups

on the basis of their construction: -

Variable Reluctance motor.

Permanent Magnet motor.

Permanent Magnet Hybrid motor.

STEPPER MOTOR TYPESThere are three basic stepper motor types. They are: -

• Variable-reluctance

• Permanent magnet

• Hybrid

Variable-reluctance (VR)This type of stepper motor has been around for a long time. It is probably the easiest to

understand from a structural point of view. Figure 1 shows a cross section of a typical

V.R. stepper motor. This type of motor consists of a soft iron multi-toothed rotor and a

wound stator. When the stator windings are energized with DC current the poles become

magnetized. Rotation occurs when the rotor teeth are attracted to the energized stator

poles.

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Cross-section of a variable reluctance (VR) motor

Permanent Magnet (PM)Often referred to as a “tin can” or “canstock” motor the permanent magnet step motor is a

low cost and low-resolution type motor with typical step angles of 7.5° to 15°. (48 – 24

steps/revolution) PM motors as the name implies have permanent magnets added to the

motor structure. The rotor no longer has teeth as with the VR motor. Instead the rotor is

magnetized with alternating north and south poles situated in a straight line parallel to the

rotor shaft. These magnetized rotor poles provide an increased magnetic flux intensity

and because of this the PM motor exhibits improved torque characteristics when

compared with the VR type.

Hybrid (HB)The hybrid stepper motor is more expensive than the PM stepper motor but provides

better performance with respect to step resolution, torque and speed. Typical step angles

for the HB stepper motor range from 3.6° to 0.9° (100 – 400 steps per revolution). The

hybrid stepper motor combines the best features of both the PM and VR type stepper

motors. The rotor is multi-toothed like the motor and contains an axially magnetized

concentric magnet around its shaft.

The teeth on the rotor provide an even better path, which helps guide the magnetic flux to

preferred locations in the airgap. This further increases the detent, holding and dynamic

torque characteristics of the motor when compared with both the VR and PM types.

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The two most commonly used types of stepper motors are the permanent magnet and the

hybrid types. If a designer is not sure which type will best fit his applications

requirements he should first evaluate the PM type as it is normally several times less

expensive. If not then the hybrid motor may be the right choice.

There also exist some special stepper motor designs. One is the disc magnet motor. Here

the rotor is designed as a disc with rare earth magnets (Fig. 2). This motor type has some

advantages such as very low inertia and an optimized magnetic flow path with no

coupling between the two-stator windings. These qualities are essential in some

applications.

Magnetic flux path through a two-pole stepper motor with a lag between the rotor and

stator.

INDUSTRIAL APPLICATION OF STEPPER MOTORS

o Floppy Disk Drives.

o Hard Disk Drives.

o Printers, Plotters.

o Electronic Watches.

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o Electronic Typewriters.

o Teleprinter, Telex-machines.

o Robotics.

o CNC-System.

o Instrumentation Control.

The main reason for the use of stepper motor instead of ordinary DC motors in disk

drives is requirement to position the read/write header. Stepper motors can be rotated at a

fixed angle and their angular rotation can be converted into linear movements to move

the read/write head over the disk surface in a fixed increment.

CONSTRUCTIONAL FEATURESA two-phase bipolar stepper motor has two coils A and B which are wound around the

upper and lower halves of stator as shown in figure 1. The stator surrounds a rotor that

contains specifically aligned permanent magnets. The number of steps per revolutions

determined by the number of pole pairs on the rotor and stator. The cross sectional view

of stator and rotor of the stepper motor are clearly depicted in figure 1 and 2.

The stepper motor are clearly used in our circuit is having 10 pole rotor structure but still

6 pole rotor structure has been depicted in figure 2 for simplicity of the figure and easy

understanding principle.

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Stator:Stator of the stepper motor has salient poles on which concentrated windings A and B are

wound. These windings are appropriately connected so as to result in two-phase windings

on stator. The salient pole structure of stator is continuous from one end to other end of

the rotor.

Rotor:The rotor of stepping motor does not carry any winding. The rotor is made up of

ferromagnetic material.

A schematic view of a bipolar hybrid stepping motor is shown in figure 2. It consists an

axial permanent magnet at the two ends of which are attached tow identical

ferromagnetic stacks as shown. These stacks consist of equal number of teeth and there

are three teeth on each stack. At one end the stack attains north magnetic polarity and at

other end stack gets south magnetic polarity. The two stacks have an angular

displacement of one half of the rotor tooth pitch.

Once the voltage is applied to the windings, the permanent magnet rotor of stepper motor

assumes it unloaded holding position. This means that the permanent magnet poles of

rotor are aligned according to the electromagnetic pole on the stator. The maximum

torque with which the excited motor can be loaded without causing a continuous rotation

is termed as stepper motor holding torque. A torque can also be perceived with a non-

excited motor. This is because of the pole induction of permanent magnet on stator. This

effect known as cogging together with motor internal friction produces detent torque,

which is the torque with which a non-excited motor can be statically loaded.

PRINCIPLE OF OPERATION:

The stepper motor is having a 10 pole rotor structure i.e. the rotor is axial permanent

magnet type with ferromagnetic stacks of opposite polarities on the opposite ends. The

numbers of stacks are 5 on each end. But for simplicity of the explanation of underlining

we will first describe a simple PMDC stepper motor with two poles on rotor.

WORKING OF A SINGLE PMDC STEPPER MOTOR: -

A simple PMDC motor with two coils A A' and B B' wound on stator and the motor

having a two pole structure is shown in figure along side. The operation of this motor is

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clearly described in steps below with the corresponding figure showing the magnetic flux

linkage between stator and rotor structures is shown along side:

Referring to figure 3. Now if the terminal A and B of stator windings are

connected to the positive voltage, then two stator magnetic field vectors Fa and Fb will

be produced as shown in fig.3. The rotor will position itself in such a way as to lock its

north pole to the resulting stator south pole and vice versa. The rotor will move in anti-

clockwise direction.

1. Refer figure 4. When the voltage polarity of coil A A' is revered with coil B B'

energized a before, the resultant stator magnetic field vector F will be at 900 from its

former position. Hence the rotor will move through a fixed angle of +900 as shown.

2. Refer figure 5. With coil A A' energized as before the voltage polarity of coil B B' is

reversed. The rotor will move through another 900 to align itself with the resultant stator

magnetic field F as shown.

3.Refer figure 6. With coil B B' energized as before, the voltage polarity of coil A is

again reversed. The motor will further move through another 900 to align itself with the

resultant stator magnetic field F as shown.

4.Refer figure 6. With coil A A' energized as before the voltage polarity of coil B B' is

again reversed. The rotor will align itself as shown.

So the motor can be made to step in one direction by continuously changing the direction

of current through these coils. To step in reverse direction the direction of current should

be changed in reverse order through these coils. This method is called two phases on full

step drive since the two-phase coils are energized together.

PRINCIPLE OF A SINGLE PMDC STEPPER MOTOR:-

The principle of operation of PMDC stepper motor having been clearly described above

will now help us to have a clearer picture of working of hybrid stepper motor. We take

the simpler case of 6 pole on the rotor structure and explain its working.

Referring to figure 7, 8, 9 the north poles are at the front end shown with full lines

whereas the south poles are at far end shown with dotted lines.When phase A winding is

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energized with current Ia North Pole at A and South Pole at A' are created on the stator.

Pole at A attracts South Pole of far end and pole at A' attracts North Pole at front end as

shown in figure 7.

This equilibrium position of rotor structure results in maximizing the flux linkages with

the phase winding A. For turning the rotor clockwise through a

step de-energies phase winding A and excite phase winding B so that North pole at B and

South pole at B' are created on the stator. Pole at B attracts the pole of rear end and pole

at B' attracts North Pole of front end, so a step angular rotation of 300 clockwise is

achieved as in figure 8. In this equilibrium position, maximum flux linkages are now

linked with phase winding B. If excitation is removed from phase winding B and reverse

excitation is applied to phase winding A, pole on A attracts North pole and pole at A'

attracts rear S pole as in figure 9. In this manner 12 steps will complete one revolution.

Sequence of exciting the phase windings for clockwise rotation is A B A' B' A and

therefore for anticlockwise rotation the sequence will be

A B' A' B A.

The magnitude of step angle

For Hybrid stepper motor = 3600/mP

Where m = number of stator phases

P = number of poles on rotor structure.

The working of actual bipolar hybrid stepper motor used in the project can now be

analogically understood. The only difference in the hybrid stepper motor described earlier

and the one used in our project is that the numbers of poles on the rotor structure are

different. In our motor we have 10-pole rotor structure i.e. 5 pole of North and South

polarity on the two ends of an axial permanent magnet.

Some terms applicable to stepping motors are as under:

Step angle is the angle through which the shaft rotates in response to one input pulse.

Single step resolution is inversely proportional to step angle. Smaller the step angle

greater the number of steps per revolution and therefore higher single step resolution.

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At stand still the excited motor opposes the rotor rotation due to load torque. Holding

torque is a term introduced for the measure of this opposing torque.

Thus holding torque is defined as the maximum load torque that can be applied to the

shaft of an excited motor without continuous rotation.In case motor is unexcited the

permanent magnet hybrid stepping motors are able to develop a torque restricting the

rotor rotation. The term detent torque is defined as the maximum load torque that can be

applied to shaft of an unexcited motor without causing continuous rotation.

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DC MOTORS VS. STEPPER MOTORS

Stepper motors are operated open loop, while most DC motors are operated closed

loop.

Stepper motors are easily controlled with microprocessors, however logic and drive

electronics are more complex.

Stepper motors are brushless and brushes contribute several problems, e.g., wear,

sparks, electrical transients.

DC motors have a continuous displacement and can be accurately positioned, whereas

stepper motor motion is incremental and its resolution is limited to the step size.

Stepper motors can slip if overloaded and the error can go undetected. (A few stepper

motors use closed-loop control.)

Feedback control with DC motors gives a much faster response time compared to

stepper motors.

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DESCRIPTION OF BREAKING COIL

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Desining:Drum brakes, depending on the way the shoes are hinged, can have a "self-servo"

characteristic. This increases stopping power without any additional effort by the

driver because the rotation of the drum drags the shoes around with it, increasing the force holding

them together. In rear brakes (as illustrated above) only one shoe will have this characteristic. Front

drum brakes may use two actuating cylinders which allow both shoes to utilize the servo

characteristic and which also increase the front axle braking force, required to compensate for

forward weight shift and also to avoid premature rear-wheel locking. Servo action can be used to

make a very powerful brake (as on the rear axles of large commercial vehicles), but it does reduce the

ability of the driver to modulate the brakes sensitively. (The disc brake has no self-servo effect

because the pads act perpendicularly to the rotating disc.)

Induction braking system :

The present invention relates to a brake device with a combination of power-generating and eddy-

current magnetic resistance having an outer ]-shaped fly wheel fastened on a central axle of a frame

and fitted with a permanent magnet on the inner circular edge to form a rotor type, and the fly wheel

is connected with a stator core fastened on the frame; moreover, one end of the central axle is

stretching out of the frame and fitted with a belt wheel; the front end of the frame is fitted with a

brake core adjacent to the outer edge of the fly wheel to supply a planned eddy current magnetic

resistance to the fly wheel; in accordance with such design, the device generates power by means of

the exercise force of users to drive the fly wheel to rotate, after passing through a DC power supply, it

provides display & controlling gage with power source so that the power-generating and the eddy

current magnetic resistance are integrated to reach the effect of reducing the volume and the

producing cost.

Components of induction braking system:

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1.An electromagnetic induction braking system comprising:

(a) a frame including a pair of support plates disposed in spaced manner one from the other, each said

support plate having a front edge portion defining an indentation, each said support plate having

formed therein a borehole;

(b) a fly wheel rotatably supported between said support plates of said frame, said fly wheel having a

central opening and a flanged peripheral portion radially offset there from, said fly wheel including at

least one permanent magnet secured to said peripheral portion;

(c) a stator core coupled to said frame, said stator core having a plurality of electrically conductive

windings, said stator core being electromagnetically coupled to said fly wheel for generation of an

induced electric signal responsive to the rotation thereof;

(d) a brake core securely received in said indentations of said frame support plates and disposed

adjacent said peripheral portion of said fly wheel for electromagnetic coupling therewith, said brake

core including a plurality of electrically conductive windings formed about a plurality of plates of

predetermined shape and material composition; and,

(e) a feedback assembly coupled to said stator and brake cores, said feedback assembly including at

least one power supply for electrically energizing said brake core responsive to said induced electric

signal generated by said stator core;

whereby said brake core is adapted to electromagnetically impart to said fly wheel a braking force for

opposing the rotation thereof.

2. The electromagnetic induction braking system as recited in claim 1 wherein said power supply of

said feedback assembly is an adjustable DC power supply.

3. The electromagnetic induction braking system as recited in claim 2 wherein said feedback

assembly further includes control means coupled to said adjustable DC power supply for controlling

said electrical energization of said brake core responsive to said induced electric signal generated by

said stator core.

4. The electromagnetic induction braking system as recited in claim 3 wherein said control means of

said feedback assembly includes means for gauging and displaying a system parameter.

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5. The electromagnetic induction braking system as recited in claim 3 wherein said feedback

assembly further includes:

(a) a conditioning circuit coupled to said stator core for commutating and wave-filtering said induced

electric signal generated thereby; and,

(b) a supplemental power supply coupled to said conditioning circuit for energizing said control

means responsive to said induced electric signal.

6. The electromagnetic induction braking system as recited in claim 5 further comprising coupling

means for rotatably coupling said fly wheel to said frame, said coupling means including:

(a) a central axle passing through said central opening of said fly wheel and said respective boreholes

of said frame support plates;

(b) a plurality of annular bearings coaxially coupled to said central axle; and,

(c) at least one bearing collar coaxially coupled to said central axle and secured to one said frame

support plate.

7. The electromagnetic induction braking system as recited in claim 6 wherein said predetermined

shape of said plates of said brake core is substantially an E-shape.

8. The electromagnetic induction braking system as recited in claim 7 wherein said predetermined

material composition of said plates of said brake core includes a silicon steel material.

9. An electromagnetic induction braking system comprising:

(a) a frame including a pair of support plates disposed in spaced manner one from the other, each said

support plate having a front edge portion defining an indentation, each said support plate having

formed therein a borehole;

(b) a fly wheel having a central opening and a flanged peripheral portion radially offset there from,

said fly wheel including at least one permanent magnet secured to said peripheral portion;

(c) coupling means for rotatably supporting said fly wheel between said frame support plates, said

coupling means including:

(1) a central axle passing through said central opening of said fly wheel and said respective boreholes

of said frame support plates;

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(2) a plurality of annular bearings coaxially coupled to said central axle; and,

(3) at least one bearing collar coaxially coupled to said central axle and secured to one said frame

support plate;

(d) a stator core coupled to said frame, said stator core having a plurality of electrically conductive

windings, said stator core being electromagnetically coupled to said fly wheel for generation of an

induced AC electric signal responsive to the rotation thereof;

(e) a brake core securely received in said indentations of said frame support plates and disposed

adjacent said peripheral portion of said fly wheel for electromagnetic coupling therewith, said brake

core including a plurality of electrically conductive windings formed about a plurality of substantially

E-shaped plates formed of a silicon steel composition; and,

(f) a feedback assembly coupled to said stator and brake cores, said feedback assembly including at

least one adjustable DC power supply for electrically energizing said brake core responsive to said

induced electric signal generated by said stator core, said feedback assembly further including:

(1) means coupled to said adjustable DC power supply for controlling said electrical energization of

said brake core responsive to said induced electric signal generated by said stator core, and gauging

and displaying a system parameter;

(2) a conditioning circuit coupled to said stator core for commutating and wave-filtering said induced

electric signal generated thereby; and,

(3) a supplemental DC power supply coupled to said conditioning circuit responsive zing said

control means responsive to said induced electric signal;.

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DESCRIPTION OF 555 TIMER IC’S

555 INTEGRATED CIRCUIT

(TIMER OPERATION)The 555 integrated circuit is an extremely versatile timer that can be used in many different

applications. This IC is a monolithic timing circuit that is a highly stable controller capable of

producing accurate time delays or oscillations. Additional terminals are producing are provided for

triggering or resetting if desires. In the time delay mode of resistance and a capacitor. For a stable

operation as an oscillator, the free running frequency and the duty cycle are both accurately

controlled with two external resistors and one capacitor. The circuit may be triggered and reset on

falling waveforms, and the output structure can source or sink up to 200ma or drive TTL Circuits.

This integrated circuit contains nearly 25 transistor, a diode or two, and more than 10 resistors.

Obviously, if you built this IC from separate components, it would be many, many times larger than

on a monolithic chip.

The 555 timer offers timing from microseconds through hours and operates in both astable and

monostable modes. It has an adjustable duty cycle, and the output can drive TTL devices. Its output

can operate in normally on and normally off modes and the IC offers a frequency stability of 0.005%

per degrees centigrade.

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Applications for the 555 chip include precision timing, pulse generation, pulse width modulation,

pulse position modulation, sequential timing, and missing pulse detection.

555-INTEGRATED CIRCUIT

IC 555-ASTABLE OPERATIONS: -If the circuit is connected as shown in figure (pins 2 and 6 connected). It will trigger itself and free

run as a multivibrator. The external capacitor charges through Ra and Rb and discharges through Rb

only. Thus, the duty cycle may be precisely set by the ratio of these two resistors. In this mode of

operation the capacitor charges and discharges between 1/3 Vcc and 2/3 Vcc. As in the triggered

mode, the charge and discharges times, and therefore, the frequency are independent of the supply

voltage. Figure shows the actual waveforms generated in this mode of operation.

The charge time (output high) is given by:

t1 = 0.685 (Ra + Rb) C

And the discharge time (output low) by:

t2 = 0.685 (Rb) C

Thus, the total period is given by:

T = t1 + t2 = 0.685 (Ra + 2Rb) C

The frequency of oscillation is then:

f = 1.46

(Ra + 2Rb) C

IC 555-MONOSTABLE OPERATIONS: -

In the monostable mode of operation, the timer functions as a one shot. Referring to figure the

external capacitor is initially held discharged by a transistor inside the timer. Upon

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applications of a negative trigger pulse to pin 2, the flip-flop is set, which releases the short circuit

across the external capacitor and drives the output high. The voltage across the capacitor increases

exponentially with the time constant.

t = Ra C

When the voltage across the capacitor equals 2/3 Vcc. The comparator resets the flip-flop, which, in

turn, discharges the capacitor rapidly and drives the output to its low state. Figure shows the actual

waveforms generated in this mode of operation.

The circuit triggers on a negative going input signal reaches 1/3 Vcc. Once triggered, the circuit will

remain in this state until the set time is elapsed, even if it is triggered again during this interval. The

time that the output is in the high state is given by: t= 1.1 Ra C

Applying a negative pulse to the reset terminal (pin 4) during the timing cycle discharges the external

capacitor and causes the cycle to start over again. The timing cycle wiw commence on the positive

edge of the reset pulse. During the time the reset pulse is applied, the output is driven to its low state

DESCRIPTION OF DIFFERENT TYPES OF RELAYS

RELAYRelay is a common, simple application of electromagnetism. It uses an electromagnet made from an

iron rod wound with hundreds of fine copper wire. When electricity is applied to the wire, the rod

becomes magnetic. A movable contact arm above the rod is then pulled toward the rod until it closes

a switch contact. When the electricity is removed, a small spring pulls the contract arm away from the

rod until it closes a second switch contact. By means of relay, a current circuit can be broken or

closed in one circuit as a result of a current in another circuit.

Relays can have several poles and contacts. The types of contacts could be normally open and

normally closed. One closure of the relay can turn on the same normally open contacts; can turn off

the other normally closed contacts.

Relay requires a current through their coils, for which a voltage is applied. This voltage for a relay

can be D.C. low voltages up to 24V or could be 240V a.c. When the voltage across the capacitor

equals 2/3 Vcc. The comparator resets the flip-flop, which, in turn, discharges the capacitor rapidly

and drives the output to its low state. Figure shows the actual waveforms generated in this mode of

operation.

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The circuit triggers on a negative going input signal when the level reaches 1/3 Vcc. Once triggered,

the circuit will remain in this state until the set time is elapsed, even if it is triggered again during this

interval. The time that the output is in the high state is given by: t= 1.1 Ra C

Applying a negative pulse to the reset terminal (pin 4) during the timing cycle discharges the external

capacitor and causes the cycle to start over again. The timing cycle will now commence on the

positive edge of the reset pulse. During the time the reset pulse is applied, the output is driven to its

low state.

A relay is an electrical switch that opens and closes under control of another electrical circuit. In the

original form, the switch is operated by an electromagnet to open or close one or many sets of

contacts. It was invented by Joseph Henry in 1835. Because a relay is able to control an output circuit

of higher power than the input circuit, it can be considered, in a broad sense, to be a form of electrical

amplifier.

These contacts can be either Normally Open (NO), Normally Closed (NC), or change-over

contacts.

Normally-open contacts connect the circuit when the relay is activated; the circuit is disconnected

when the relay is inactive. It is also called Form A contact or "make" contact. Form A contact is

ideal for applications that require to switch a high-current power source from a remote device.

Normally-closed contacts disconnect the circuit when the relay is activated; the circuit is

connected when the relay is inactive. It is also called Form B contact or "break" contact. Form B

contact is ideal for applications that require the circuit to remain closed until the relay is activated.

Change-over contacts control two circuits: one normally-open contact and one normally-closed

contact with a common terminal. It is also called Form C contact.

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Operation:

When a current flows through the coil, the resulting magnetic field attracts an armature that is

mechanically linked to a moving contact. The movement either makes or breaks a connection with a

fixed contact. When the current to the coil is switched off, the armature is returned by a force that is

half as strong as the magnetic force to its relaxed position. Usually this is a spring, but gravity is also

used commonly in industrial motor starters. Relays are manufactured to operate quickly. In a low

voltage application, this is to reduce noise. In a high voltage or high current application, this is to

reduce arcing.

If the coil is energized with DC, a diode is frequently installed across the coil, to dissipate the energy

from the collapsing magnetic field at deactivation, which would otherwise generate a spike of voltage

and might cause damage to circuit components. If the coil is designed to be energized with AC, a

small copper ring can be crimped to the end of the solenoid. This "shading ring" creates a small out-

of-phase current, which increases the minimum pull on the armature during the AC cycle. [1]

By analogy with the functions of the original electromagnetic device, a solid-state relay is made with

a thyristor or other solid-state switching device. To achieve electrical isolation, a light-emitting diode

(LED) is used with a photo transistor.

Relays are used: to control a high-voltage circuit with a low-voltage signal, as in some types of modems,

to control a high-current circuit with a low-current signal, as in the starter solenoid of an

automobile ,

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to detect and isolate faults on transmission and distribution lines by opening and closing circuit

breakers (protection relays),

to isolate the controlling circuit from the controlled circuit when the two are at different

potentials, for example when controlling a mains-powered device from a low-voltage switch. The

latter is often applied to control office lighting as the low voltage wires are easily installed in

partitions, which may be often moved as needs change. They may also be controlled by room

occupancy detectors in an effort to conserve energy,

to perform logic functions. For example, the boolean AND function is realised by connecting NO

relay contacts in series, the OR function by connecting NO contacts in parallel. The change-over or

Form C contacts perform the XOR (exclusive or) function. Similar functions for NAND and NOR are

accomplished using NC contacts. Due to the failure modes of a relay compared with a semiconductor,

they are widely used in safety critical logic, such as the control panels of radioactive waste handling

machinery.

to perform time delay functions. Relays can be modified to delay opening or delay closing a set of

contacts. A very short (a fraction of a second) delay would use a copper disk between the armature

and moving blade assembly. Current flowing in the disk maintains magnetic field for a short time,

lengthening release time. For a slightly longer (up to a minute) delay, a dashpot is used. A dashpot is

a piston filled with fluid that is allowed to escape slowly. The time period can be varied by increasing

or decreasing the flow rate. For longer time periods, a mechanical clockwork timer is installed.

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DESCRIPTION OF THE IR TRANSMITER AND

RECIEVER CIRCUIT

PHOTO-DIODESIf a conventional silicon diode is connected in the reverse-biased circuit of fig. 1, negligible current

will flow through the diode and zero voltage will develop across R1. If the diode casing is now

carefully removed so that the diode's semiconductor junction is revealed, and the junction is them

exposed to visible light in the same circuit, the diode current will rise, possibly to as

Reverse-baised diode circuit.

high as 1 mA, producing a significant output across R1. Further investigation will show that the diode

current (and thus the output voltage) is directly proportional to light intensity, and that the diode is

therefore photosensitive.

In practice, all silicon junctions are photosensitive, and a photodiode can be regarded as a

conventional diode housed in a case that lets external light reach its photosensitive semiconductor

junction. Fig. 2 shows the standard photodiode symbol. In use, the photodiode is reverse biased and

the output voltage is taken from across a series-connected load resistor. This resistor may be

connected between the diode and ground, as in fig. 1, or between the diode and the positive supply

line, as in fig. 3

Photodiode symbol

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The human eye is sensitive to a range of light radiation, as shown in fig. 4. It has a peak spectral

response to the colour green, which has a wave length of about 550 nm, but has a relatively low

sensitivity to the colour violet (400 nm) at one end of the spectrum and to dark red (700 nm) at the

other. Photodiodes also have spectral response characteristics, and these are determined by the

chemistry used in the semiconductor junction material. Fig. 4 shows typical response curves of a

general-purpose photodiode, and infrared (IR) photodiode.

Photodiodes have a far lower light-sensitivity than cadmium-sulphide LDRs, but give a far quicker

response to changes in light level. Generally, LDRs are ideal for use in slow-acting direct-coupled

light-level sensing applications, while photodiodes are ideal for use in fast-acting AC-coupled

signaling applications. Typical photodiode applications include IR remote-control circuits, IR beam

switches and alarm circuits, and photographic flash slave circuits, etc. which can be regarded as a

conventional transistor housed in a case that enables its semiconductor junctions to be exposed to

external light. The device is normally used with its base open circuit, in either of the configurations

shown in fig. 6, and functions as follows.

Phototransistor symbol.In fig. 6(a), the base-collector junction of the transistor is effectively reverse biased and thus acts as a

photodiode. The photo-generated currents of the base-collector junction feed directly into the base of

the device, and the normal current-amplifying transistor action causes the output current to appear (in

greatly amplified form) as collector current, and in fig. 6(a) R1 causes this current to generate an

output voltage as shown.

In practice, the collector and emitter current of the transistor are virtually identical and, since the base

is open circuit, the device is not subjected to significant negative feedback. Consequently, the

alternative fig. 6(b) circuit, in which R1 is connected to Q1 emitter, gives a virtually identical

performance to that of fig. 6(a).

Alternative phototransistor configuration.The sensitivity of a phototransistor is typically one hundred times greater than that of a photodiode,

but is useful maximum operating frequency (a few hundred kilohertz) is proportionally lower than

that of a photodiode by using only its base and collector terminals and ignoring the emitter.

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INFRARED SENSOR:

WORKING OF THE INFRARED SENSORIn this IR detector and transmitter circuit the IC 555 is working under astable mode. The pin 4 i.e.

reset pin is when grounded via IR receiver the pin 3 output is low. As soon as the IR light beam

transmitted is obstructed, a momentary pulse actuates the relay output (or LED). The IR transmitter is

simple series connected resistor network from battery. The timing capacitor connected to pin 2 and

ground can varied as per requirement.

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DESCRIPTION OF GEARS

GEARGears, toothed wheels or cogs are positive type drives which are used to transmit motion between

two shafts or a shaft and a component having linear motion, by meshing of two or more gears. They

have advantage over other drives like chains, belts etc. in case of precision machines where a definite

velocity ratio is of importance and also in case where the driver and the follower are in close

proximity; the downside is that gears are more expensive to manufacture and their operating cost is

also relatively high.

Spur gears found on a piece of farm equipment .

and the smaller as Gears of differing size are often used in pairs for a mechanical advantage, allowing

the torque of the driving gear to produce a larger torque in the driven gear at lower speed, or a smaller

torque at higher speed. The larger gear is known as a wheel a pinion. This is the principle of the

automobile transmission, allowing selection between various mechanical advantages.

The ratio of the rotational speeds of two meshed gears is called the Gear ratio.

A gearbox is not an amplifier or a servomechanism. Conservation of energy requires that the amount

of power delivered by the output gear or shaft will never exceed the power applied to the input gear,

regardless of the gear ratio. Work equals the product of force and distance, therefore the small gear is

required to run a longer distance and in the process is able to exert a larger twisting force or torque,

than would have been the case if the gears were the same size. There is actually some loss of output

power due to friction.

TYPES:

SPUR GEARSThe most common type of gear wheel, spur gears, are flat and have teeth projecting radially and in

the plane of the wheel. The teeth of these "straight-cut gears" are cut so that the leading edges are

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parallel to the line of the axis of rotation. These gears can only mesh correctly if they are fitted to

parallel axles.

HELICAL GEARSHelical gears offer a refinement over spur gears. The teeth are cut at an angle, allowing for more

gradual, hence smoother meshing between gear wheels, eliminating the whine characteristic of

straight-cut gears. A disadvantage of helical gears is a resultant thrust along the axis of the gear,

which needs to be accommodated by appropriate thrust bearings, and a greater degree of sliding

friction between the meshing teeth, often addressed with specific additives in the lubricant. Whereas

spur gears are used for low speed applications and those situations where noise control is not a

problem, the use of helical gears is indicated when the application involves high speeds, large power

transmission, or where noise abatement is important. The speed is considered to be high when the

pitch line velocity (ie. circumferential velocity) exceeds 5000 ft/min or the rotational speed of the

pinion (ie. smaller gear) exceeds 3600 rpm.

Helical gears from a Meccano construction set .

DOUBLE HELICAL GEARSDouble helical gears, invented by André Citroën and also known as herringbone gears, overcome the

problem of axial thrust presented by Single helical gears by having teeth that are 'V' shaped. Each

gear in a double helical gear can be thought of as two standard, but mirror image, helical gears

stacked. This cancels out the thrust since each half of the gear thrusts in the opposite direction. They

can be directly interchanged with spur gears without any need for different bearings.

BEVEL GEARSWhere two axles cross at point and engage by means of a pair of conical gears, the gears themselves

are referred to as bevel gears. These gears enable a change in the axes of rotation of the respective

shafts, commonly 90°. A set of four bevel gears in a square make a

differential gear, which can transmit power to two axles spinning at different speeds, such as those on

a cornering automobile.

Helical gears can also be designed to allow a ninety degree rotation of the axis of rotation.

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Bevel gear in floodgate

WORM GEARIf the axles are skewed, that is, non-parallel, then a worm gear can be used. This is a gear that

resembles a screw, with parallel helical teeth, and mates with a normal spur gear. The worm is always

the driving gear. The worm gear can achieve a higher gear ratio than spur gears of a comparable size.

Designed properly, a built in safety feature can be obtained: This gear style will self-lock if power is

lost to the drive (worm). It doesn't work if the pinion is powered.

A Worm Gear and Pinion from a Meccano construction set

RACK AND PINIONTorque can be converted to linear force by a rack and pinion. The pinion is a spur gear, and meshes

with a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius of

curvature. Such a mechanism is used in automobiles to convert the rotation of the steering wheel into

the left-to-right motion of the tie rod(s).

CROWN GEARA crown gear or contrate gear is a special form of bevel gear which has teeth at right angles to the

plane of the wheel; it meshes with a straight cut spur gear or pinion on a right-angled axis to its own,

or with an escapement such as found in mechanical clocks.

Simple gears suffer from backlash, which is the error in motion that occurs when gears change

direction, resulting from hard to eliminate manufacturing errors. When moving forwards, the front

face of the drive gear tooth pushes on the rear face of the driven gear. When the drive gear changes

direction, its rear face is now pushing on the front face of the driven gear. Unless deliberately

designed to eliminate it, there is slight 'slop' in any gearing where briefly neither face of the driving

gear is pushing the driven gear. This means that input motion briefly causes no output motion.

Assorted schemes exist to minimize or avoid problems this creates.

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\

34

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DESCRIPTOIN OF RESISTANCES

RESISTANCEResistance 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 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

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

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

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

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

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

Green------------------------------------------------------------------5

Blue--------------------------------------------------------------------6

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

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

White------------------------------------------------------------------9 The first rings give the first digit. The second ring gives the second digit. 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%).

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 contact resistance in this case is small &

constant.

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DESCRIPTION OF CAPACITANCES

CAPACITORSIt 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 in

radio 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 (I pf=1/1000,

000,000,000 f) Above all, in case of electrolytic

capacitors, its two terminal are marked as (-) and

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(+) so check it while using capacitors in the circuit in right direction. Mistake can destroy the

capacitor or entire circuit in operational.

WORKING OF SOLDERING……………?????

PROCEDURE FOR MAKING PROJECTBuilding project in the proper manner is really an art, something which must be prectised and learned

through trial and error, it is not all that difficult. The main thing is to remember to take each step

slowly and carefully according to the instructions giving making since that everything at it should be

before proceeding further.

TOOLS: The electronics workbench is an actual place of

work with comfortably & conveniently & should be supplied

with compliment of those tools must often use in project

building. Probably the most important device is a soldering

tool. Other tool which should be at the electronic work

bench includes a pair of needle nose pliers, diagonal wire

cutter, a small knife, an assortment of screw driver, nut

driver, few nuts & bolts, electrical tape, plucker etc. Diagonal

wire cutter will be used to cut away any excess lead length from copper side of P.C.B. 7 to cut section

of the board after the circuit is complete. The needle nose pliers are most often using to bend wire

leads & wrap them in order to form a strong mechanical connection.

MOUNTING & SOLDERING:

Soldering is process of joining together two metallic

parts. It is actually a process of function in which an

alloy, the solder, with a comparatively low melting

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point penetrates the surface of the metal being joined & makes a firm joint between them on cooling

& solidifying.

THE SOLDERING KIT

1. SOLDERING IRON: As soldering is a process of joining together two

metallic parts, the instrument, which is used, for doing this job is known as soldering Iron.

Thus it is meant for melting the solder and to setup the metal parts being joined. Soldering Iron is

rated according to their wattage, which varies from 10- 200 watts.

2. SOLDER:The raw material used for soldering is solder. It is composition of lead & tin. The good quality solder

(a type of flexible naked wire) is 60% Tin +40% Lead which will melt between 180 degree to 200

degree C temperature.

3. FLUXES OR SOLDERING PASTE:When the points to solder are heated, an oxide film forms. This must be removed at once so that

solder may get to the surface of the metal parts. This is done by applying chemical substance called

Flux, which boils under the heat of the iron remove the oxide formation and enable the metal to

receive the solder.

4. BLADES OR KNIFE:To clean the surface & leads of components to be soldered is done by this common instrument.

5. SAND PAPER:The oxide formation may attack at the tip of your soldering iron & create the problem. To prevent

this, clean the tip with the help of sand paper time to time or you may use blade for doing this job.

Apart from all these tools, the working bench for soldering also includes desoldering pump, wink

wire (used for desoldering purpose), file etc.

HOW TO SOLDER?Mount components at their appropriate place; bend the leads slightly outwards to prevent them from

falling out when the board is turned over for soldering. No

cut the leads so that you may solder them easily. Apply a small amount of flux at these components

leads with the help of a screwdriver. Now fix the bit or iron with a small amount of solder and flow

freely at

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the point and the P.C.B copper track at the same time. A good solder joint will appear smooth &

shiny. If all appear well, you may continue to the next solder connections.

1. Mount the components at the appropriate places before soldering. Follow the circuit description

and components details, leads identification etc. Do not start soldering before making it confirm that

all the components are mounted at the right place.

2. Do not use a spread solder on the board, it may cause short circuit.

3. Do not sit under the fan while soldering.

4. Position the board so that gravity tends to keep the solder where you want it.

5. Do not over heat the components at the board. Excess heat may damage the components or board.

6. The board should not vibrate while soldering otherwise you have a dry or a cold joint.

7. Do not put the kit under or over voltage source. Be sure about the voltage either dc or ac while

operating the gadget.

8. Do spare the bare ends of the components leads otherwise it may short circuit with the other

components. To prevent this use sleeves at the component leads or use sleeved wire for connections.

9. Do not use old dark colour solder. It may give dry joint. Be sure that all the joints are clean and

well shiny.

10. Do make loose wire connections especially with cell holder, speaker, probes etc. Put knots

while connections to the circuit board, otherwise it may get loose.

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Circuit Design

The important components of this car are DTMF decoder, microcontroller and motor driver.

An MT8870 series DTMF decoder is used here. All types of the MT8870 series use digital

counting techniques to detect and decode all the 16 DTMF tone pairs into a 4-bit code output.

The built-in dial tone rejection circuit eliminates the need of pre-filtering. When the input

signal given at pin 2(IN-) in single-ended input configuration is recognized to be effective, the

correct 4-bit decode signal of the DTMF tone is transferred to (pin11) through (pin14)

outputs. The pin11 to pin14 of DTMF decoder are connected to the pins of microcontroller

(pa0 to pa3).The ATmega16 is a low power, 8-bit CMOS microcontroller based on the AVR

enhanced RISC architecture. It provides the following features: 16kb of in-system

programmable flash program memory with read-while-write capabilities, 512 bytes of

EEPROM, 1kb SRAM, and 32 (I\O) lines. Outputs from port pins PD0 through PD3 and PD7

of the microcontroller are fed to the inputsIN1 through IN4 and enable pins (EN1 and EN2) of

motor driver L293D IC, respectively to drive two geared dc motors. Switch S1 is used for

manual reset. The microcontroller output is not sufficient to drive the dc motors, so Current

drivers are required for motor rotation. The L293D is a quad, high- current, half-h driver

designed to provide bidirectional drive currents of up to 600mA at voltages from 4.5V to

36V. It makes it easier to drive the dc motors. The L293D consists of four drivers. Pins IN1

through IN4 and OUT1 through OUT4 are the input and output pins respectively, of driver 1

through driver 4. Drivers 1 and 2, and driver 3 and 4 are enabled by enable pin 1(EN1) and

pin 9 (EN2), respectively. When enable input EN1 (pin1) is high, drivers 1 and 2 are.

In order to control the toy car, a call need to make to the cell phone attached to the toy car

(through headphone) from any phone, which sends DTMF tunes on pressing the numeric

buttons. The cell phone in the car kept in 'auto answer' mode. So after a ring, the cell phone

accepts the call. Now particular button may press on the mobile phone for pre-defined desired

action. The DTMF tones thus produced are received by the cell phone in the car. These tones

are fed to the circuit by headset of the cell phone. The MT8870 decodes the received tone and

sends the equivalent binary number to the microcontroller. According to the program in the

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microcontroller, the car starts moving. When the number key '2' (binary equivalent 00000010)

is pressed on the mobile phone, the microcontroller outputs ‘10001001’binary equivalent.

Port pins PD0, PD3 and PD7 are high. The high output at PD7 of the microcontroller drives

the motor driver (L293D).

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Port pins PD0 and PD3 drive motors M1 and M2 in forward direction (as per table).

Similarly, stop condition as per the condition. Details conditions are shown in the

flow chart diagram.

The primary objective of this project was to build a cell phone link between a

transmitter and a dumb car and provide the capability to operate the car from a remote

location. The purpose of using the cell phone was to make the operation possible from

any remote location in the world where cell phone use is available. The product would

include two interface systems. One interface would operate between the transmitter

and a sending cell phone, and a second interface would operate between the receiving

cell phone and the dumb car. The interface on the sending side would allow

production and encoding of signals suitable for transmission via a cell phone. The

interface on the receiving end would process the signals received by the cell phone

and control the dumb car. The simple diagram below illustrates the concept of the

project.

In order to the work properly this system, certain specifications are made. They are:

• The system must have an interface between the transmitter, the sending phone and

another interface between the receiver phone and the robot.

• The cell phones should be any common cell phone. However, a specific model can

be chosen because of hands free set connection type.

• Very negligible delay compare to the operation of the off-the-shelf unit one.

• The system should be a low power device.

• Both mobile phones should have activated DTMF service for controlling the robot

from a remote location.

The working procedure for this model is very simple. At first, the robot needs to turn

ON by giving power supply of 10v battery. Now dial a mobile number that is

connected with robot at remote location. Then after ringing the remote mobile

connected with robot, it will automatically connected by Auto-Answer option in

mobile phone just like an internet connection established between two systems. It

needs to be ensured that DTMF tones sending facility should be active between both

mobiles. After connection establishment the keyboard need to use to operate the robot

car in particular direction.

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There are 3 main parts of this system. They are the decoder, microcontroller and the

motor driver. The following paragraph explains about their working procedure in

briefly. The MT-8870 DTMF DECODER IC is a full DTMF Receiver that integrates

both band split filter and decoder functions into a single18-pin DIP or SOIC package.

Manufactured using CMOS process technology, the M-8870 offers low power

consumption (35mW max) and precise data handling. Its filter section uses switched

capacitor technology for both the high and low group filters and for dial tone

rejection. Its decoder uses digital counting techniques to detect and decode all 16

DTMF tone pairs into a 4-bit code. External component count is minimized by

provision of an on-chip differential input amplifier, clock generator and latched tri-

state interface bus. Minimal external components required include a low-cost

3.579545 MHz color burst crystal, a timing resistor, and a timing capacitor. The M-

8870-02 provides a “power-down” option which, when enabled, drops consumption to

less than 0.5mW . The M-8870-02 can also inhibit the decoding of fourth column

digits. M-8870 operating functions include a band split filter that separates the high

and low tones of the received pair and a digital decoder that verifies both the

frequency and duration of the received tones before passing the resulting 4-bit code to

the output bus.

The low and high group tones are separated by applying the dual-tone signal to the

inputs of two 6th order switched capacitor band pass filters with bandwidths. That

44

corresponds to the bands enclosing the low and high group tones. The filter also

incorporates notches at 350 and 440 Hz, providing excellent dial tone rejection. Each

filter output is followed by a single-order switched capacitor section that smoothes the

signals prior to limiting. Signal limiting is performed by high gain comparators

provided with hysteresis to prevent detection of unwanted low-level signals and noise.

The comparator outputs provide full-rail logic swings at the frequencies of the

incoming tones. Decoder the M-8870 uses a digital counting technique to determine

the frequencies of the limited tones and to verify that they correspond to standard

DTMF frequencies . A complex averaging algorithm is used to protect against tone

simulation by extraneous signals (such as voice) while tolerating small frequency

variations. The algorithm ensures an optimum combination of immunity to talk off

and tolerance to interfering signals (Third tones) and noise. When the detector

recognizes the simultaneous presence of two valid tones (known as signal condition),

it raises the Early Steering flag (Est.) . Any subsequent loss of signal condition will

cause Est. to fall.

As the microcontroller used in this system is a very popular one hence the details

about this microcontroller is show explained here. However, information about the

ATMEGA16 microcontroller can be found on.

The L293D IC (Motor Driver) Device is a monolithic integrated high voltage, high

current four channel driver designed to accept standard DTL or TTL logic levels and

drive inductive loads (such as relays solenoids, DC and stepping motors) and

switching power transistors . To simplify use as two bridges each

pair of channels is equipped with an enable input. A separate supply input is provided

for the logic, allowing operation at a lower voltage and internal clamp diodes are

included. This device is suitable for use in switching application at frequencies up to 5

kHz. The L293D is assembled in a 16 lead plastic Package which has 4 center pins

connected together and used for heat sinking. The L293DD is assembled in a 20 lead

surface Mount which has 8 centre pins connected together and used for heat sinking.

A circuit connection of the motor driver is shown.

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3.1 Application If we use the switching IC instead of the driver IC we can turn on and off any

appliances connected to this toy car.

This toy car can carry in their capacity.

This can be fitted in an attractive form of a toy car for child pleaser.

Adding a camera could highly increase its popularity.

Password protected systems have used in many war conditions and so on.

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Conclusion

In this project, the toy car is controlled by a mobile phone that makes a call to the

mobile phone attached to the car. In the course of a call, if any button is pressed, a

tone corresponding to the button pressed is heard at the other end of the call. This is a

wireless controller toy car hence the limitation of wired is completely overcome by

using latest technology of mobile phones. However, there are still lots of scopes to

improve the stability and ability of this system. The mobile phone that makes a call to

mobile phone stacked in the car act as a remote. Hence this project does not require

the construction of receiver and transmitter units. It is undoubtedly true that, this

model can be a very significant device in case of the information acquisition from the

remote areas where direct interference of human being is quite impossible hence it

would be a very crucial topic to do further research on it.

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Reference

* AwabFakih, JovitaSerrao, Cell Phone Operated Robotic Car. International Journal

of Scientific & Engineering Research, ISSN 2229-5518.

* L. Schenker, "Pushbutton Calling with a Two- Group Voice-Frequency Code", The

Bell System Technical Journal, 39(1), 1960, 235–255, ISSN 0005-8580

Thamilarasi, Automated Unmanned Railway Level Crossing System, International

Journal of Modern Engineering Research (IJMER), Vol.2, Issue.1, Jan-Feb 2012 pp-

458-463 ISSN: 2249-6645.

DR P.k Yadav (H.O.D)

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