INTRODUCTION

This is a very interesting project with many practical applications in security and

alarm systems for homes, shops and cars. It consists of a set of ultrasonic receiver and

transmitter which operate at the same frequency. When something moves in the area covered

by the circuit the circuits fine balance is disturbed and the alarm is triggered. The circuit is

very sensitive and can be adjusted to reset itself automatically or to stay triggered till it is

reset manually after an alarm

An electronic circuit consist of interconnection of various electrical or electronic

components or devices to fulfill a desired function. In electronic circuit, symbols are used to

represent these components or devices. It include active and passive components.

A circuit designer must have knowledge of different types of components, there

working application, characteristics, operation range, inputs, outputs and other working

conditions. The frequent knowledge of all components being used by a designer in a circuit

is essential for designer.

During designing a new circuit, a designer must have an idea of the features of the

final products and also know about the working condition, range and other essential

characteristic. Such as environmental conditions; as most of component/devices change their

characteristics with change in environment, to be desired for the final equipment. During

designing circuit; the temperature conditions of the place where the equipment is to be

placed must also be taken into account as it has tremendous effect on the performance of the

circuit.

A designer should always remain in touch with latest inventions and developments

which are taking place in the field of circuit designer. At the time of selection of a

component in a circuit, a designer must keep in mind about the substitute components which

will give better performance and high accuracy to the final equipment.

A designer must keep in mind both the positive and negative effect of each and every

components to be used in a circuit. For example use of certain components can induce

capacitance and inductance in the circuit.

1

CHAPTER-1

1.1 ULTRASONIC RADAR

1.1.1 INTRODUCTION

A surprising number of new instruments may be available, too, many through the

grouping of either the Goldstone or Arecibo antenna in tandem with a radio telescope to

form a bistatic radar. The Goldstone-VLA radar appears to point the way to additional

combinations with the soon-to-be-completed Green Bank radio telescope, or perhaps to the

Goldstone X-band radar in tandem with a tracking station in the Soviet Union. Already, the

Russian Yevpatoriya tracking station has made bistatic observations of the asteroid Toutatis

in conjunction with the Effelsberg radio telescope, though without achieving the impressive

results of the Arecibo and Goldstone antennas. Politics and funding will limit what, if any,

future bistatic experiments take place outside the United States. Additional bistatic

possibilities in the United States include the JPL Mars Station in combination with other

Goldstone antennas, as well as an Arecibo-Goldstone link.

The bistatic possibilities are not limitless, however; not inconsequential institutional,

political, and budgetary obstacles aside, the elementary technological need for compatible

transmitting and receiving frequencies limits many bistatic options. Even more limited is the

creation of new radars. Other countries continue to build antennas, such as the Arecibo-size

dish planned in Brazil, but none anticipate a radar capability. No facility dedicated entirely

to planetary radar astronomy ever has been built; nonetheless, Steve Ostro believes that it is

time to build one in order to study asteroids. The cost of designing and building such a radar

observatory would approach the modest level budgeted for NASA's Discovery space

missions.1 The role of this facility in the Spaceguard project aside, its potential scientific

value in a short period of time would exceed that of any one Discovery flyby of an asteroid.

Time will tell whether this worthwhile and economical project is realized.

2

1.1.2 CONSTRUCTION

First of all let us consider a few basics in building electronic circuits on a printed

circuit board. The board is made of a thin insulating material clad with a thin layer of

conductive copper that is shaped in such a way as to form the necessary conductors between

the various components of the circuit. The use of a properly designed printed circuit board is

very desirable as it speeds construction up considerably and reduces the possibility of

making errors. Smart Kit boards also come pre-drilled and with the outline of the

components and their identification printed on the component side to make construction

easier. To protect the board during storage from oxidation and assure it gets to you in perfect

condition the copper is tinned during manufacturing and covered with a special varnish that

protects it from getting oxidised and also makes soldering easier. Soldering the components

to the board is the only way to build your circuit and from the way you do it depends greatly

your success or failure. This work is not very difficult and if you stick to a few rules you

should have no problems. The soldering iron that you use must be light and its power should

not exceed the 25 Watts.

The tip should be fine and must be kept clean at all times. For this purpose come very

handy specially made sponges that are kept wet and from time to time you can wipe the hot

tip on them to remove all the residues that tend to accumulate on it. DO NOT file or

sandpaper a dirty or worn out tip. If the tip cannot be cleaned, replace it. There are many

different types of solder in the market and you should choose a good quality one that

contains the necessary flux in its core, to assure a perfect joint every time. DO NOT use

soldering flux apart from that which is already included in your solder. Too much flux can

cause many problems and is one of the main causes of circuit malfunction. If nevertheless

you have to use extra flux, as it is the case when you have to tin copper wires, clean it very

thoroughly after you finish your work. In order to solder a component correctly you should

do the following:

Clean the component leads with a small piece of emery paper.Bend them at the correct

distance from the component�s body and insert the component in its place on the board.

3

You may find sometimes a component with heavier gauge leads than usual, that are

too thick to enter in the holes of the p.c. board. In this case use a mini drill to enlarge the

holes slightly. Do not make the holes too large as this is going to make soldering difficult

afterwards.

Take the hot iron and place its tip on the component lead while holding the end of the

solder wire at the point where the lead emerges from the board. The iron tip must touch the

lead slightly above the p.c. board.

When the solder starts to melt and flow wait till it covers evenly the area around the

hole and the flux boils and gets out from underneath the solder. The whole operation should

not take more than 5 seconds. Remove the iron and allow the solder to cool naturally without

blowing on it or moving the component. If everything was done properly the surface of the

joint must have a bright metallic finish and its edges should be smoothly ended on the

component lead and the board track. If the solder looks dull, cracked, or has the shape of a

blob then you have made a dry joint and you should remove the solder (with a pump, or a

solder wick) and redo it.

Take care not to overheat the tracks as it is very easy to lift them from the board and

break them.When you are soldering a sensitive component it is good practice to hold the lead

from the component side of the board with a pair of long-nose pliers to divert any heat that

could possibly damage the component.

Make sure that you do not use more solder than it is necessary as you are running the

risk of short-circuiting adjacent tracks on the board, especially if they are very close

together.

When you finish your work cut off the excess of the component leads and clean the

board thoroughly with a suitable solvent to remove all flux residues that may still remain on

it.

4

There are quite a few components in the circuit and you should be careful to avoid

mistakes that will be difficult to trace and repair afterwards. Solder first the pins and the IC

sockets and then following if that is possible the parts list the resistors the trimmers and the

capacitors paying particular attention to the correct orientation of the electrolytic.

Solder then the transistors and the diodes taking care not to overheat them during

soldering. The transducers should be positioned in such a way as they do not affect each

other directly because this will reduce the efficiency of the circuit. When you finish

soldering, check your work to make sure that you have done everything properly, and then

insert the IC�s in their sockets paying attention to their correct orientation and handling IC3

with great care as it is of the CMOS type and can be damaged quite easily by static

discharges.

Do not take it out of its aluminum foil wrapper till it is time to insert it in its socket,

ground the board and your body to discharge static electricity and then insert the IC carefully

in its socket. In the kit you will find a LED and a resistor of 560 � which will help you to

make the necessary adjustments to the circuit. Connect the resistor in series with the LED

and then connect them between point 9 of the circuit and the positive supply rail (point 1).

Connect the power supply across points 1 (+) and 2 (-) of the p.c. board and put P1 at

roughly its middle position. Turn then P2 slowly till the LED lights when you move your

fingers slightly in front of the transducers. If you have a frequency counter then you can

make a much more accurate adjustment of the circuit. Connect the frequency counter across

the transducer and adjust P2 till the frequency of the oscillator is exactly the same as the

resonant frequency of the transducer. Adjust then P1 for maximum sensitivity. Connecting

together pins 7 & 8 on the p.c. board will make the circuit to stay triggered till it is manually

reset after an alarm. This can be very useful if you want to know that there was an attempt to

enter in the place which are protected by the radar.

5

1.1.3 Components

C1, 6 = 10UF/16V

C2 = 47UF/16V

C3 = 4,7 PF

C4, 7 = 1 NF

C5 = 10NF

C8, 11 = 4,7 UF/16V

C9 = 22UF/16V

C10 = 100 NF

C12 = 2,2 UF/16V

C13 = 3,3NF

C14 = 47NF

TR1, 2, 3 = BC547 , BC548

P1 = 10 KOHM TRIMMER

P2 = 47 KOHM TRIMMER

IC1, 2 = 741 OP-AMP

IC3 = 4093 C-MOS

R = TRANSDUCER 40KHZ

T = TRANSDUCER 40KHZ

R1 =  180 KOHM

R2 =  12 KOHM

R3, 8 =  47 KOHM

R4 =  3,9 KOHM

R5, 6, 16 =  10 KOHM

R7, 10, 12, 14, 17 =  100 KΩ

R9, 11 =  1 MOHM

R13, 15 =  3,3 KOHM

 

6

      

1.1.4 WORKING

As it has already been stated the circuit consists of an ultrasonic transmitter and a

receiver both of which work at the same frequency. They use ultrasonic piezoelectric

transducers as output and input devices respectively and their frequency of operation is

determined by the particular devices in use.

The transmitter is built around two NAND gates of the four found in IC3 which are

used here wired as inverters and in the particular circuit they form a multivibrator the output

of which drives the transducer. The trimmer P2 adjusts the output frequency of the

transmitter and for greater efficiency it should be made the same as the frequency of

resonance of the transducers in use. The receiver similarly uses a transducer to receive the

signals that are reflected back to it the output of which is amplified by the transistor TR3,

and IC1 which is a 741 op-amp. The output of IC1 is taken to the non inverting input of IC2

the amplification factor of which is adjusted by means of P1. The circuit is adjusted in such a

way as to stay in balance as long the same as the output frequency of the transmitter. If there

is some movement in the area covered by the ultrasonic emission the signal

That is reflected back to the receiver becomes distorted and the circuit is thrown out

of balance. The output of IC2 changes abruptly and the Schmitt trigger circuit which is built

around the remaining two gates in IC3 is triggered. This drives the output transistors TR1,2

which in turn give a signal to the alarm system or if there is a relay connected to the circuit,

in series with the collector of TR1, it becomes activated. The circuit works from 9-12 VDC

and can be used with batteries or a power supply.

7

1.1.5 CIRCUIT DIAGRAM OF ULTRASONIC RADAR

8

1.1.6 PCB LAYOUT OF ULTRASONIC RADAR

9

CHAPTER 2

2.1 IC USED

2.1.1 PIN DIAGRAM OF HEF4017BMSI

10

DESCRIPTION

The HEF4017B is a 5-stage Johnson decade counter with ten spike-free decoded

active HIGH outputs (Oo to O9), an active LOW output from the most significant flip-flop

(O5-9), active HIGH and active LOW clock inputs (CP0, CP1) and

an overriding asynchronous master reset input (MR). The counter is advanced by either a

LOW to HIGH transition at CP0 while CP1 is LOW or a HIGH to LOW

transition at CP1 while CP0 is HIGH (see also function table).

When cascading counters, the O5-9 output, which is LOW while the counter is in

states 5, 6, 7, 8 and 9, can be used to drive the CP0 input of the next counter. (Oo = O5-9 =

HIGH; O1 to O9 = LOW) independent of the clock inputs (CP0, CP1). Automatic code

correction of the counter is provided by an internal circuit: following any illegal code the

counter returns to a proper counting mode within 11 clock pulses. Schmitt-trigger action in

the clock input makes the circuit highly tolerant to slower clock rise and fall times.

11

PINNING

CP0 clock input (LOW to HIGH triggered)

CP1 clock input (HIGH to LOW triggered)

MR master reset input

O0 to O9 decoded outputs

O5-9 carry output (active LOW)

HEF4017BP(N): 16-lead DIL; plastic (SOT38-1)

HEF4017BD(F): 16-lead DIL; ceramic (cerdip) (SOT74)

HEF4017BT(D): 16-lead SO; plastic (SOT109-1)

( ): Package Designator North America

12

5 STAGE JOHNSON COUNTER

13

1. H = HIGH state (the more positive voltage)

2. L = LOW state (the less positive voltage)

3. X = state is immaterial

4. = positive-going transition

5. = negative-going transition

Some examples of applications for the HEF4017B are:

· Decade counter with decimal decoding

· 1 out of n decoding counter (when cascaded)

· Sequential controller

· Timer.

14

2.1.2 PIN DIAGRAM OF 555 TIMER IC

15

ASTABLE AND MONOSTABLE GENERATORS THE 555 TIMER

THE 555 MONOSTABLE

In theory any combination of R and C is possible to achieve a required time period. In

practice, however, there are several things to remember.

1. The transistor connected to the DISCHARGE terminal, as well as having to conduct the

short-circuit current of the timing capacitor when the monostable resets, also has to carry

the current flowing through the timing resistor. To prevent destruction of this transistor

the minimum value of R should be 1k.

2. The minimum value of C should be considered as 100pF, since any smaller value will be

similar to the input capacitance of the timer circuit and so the time periods will be

inaccurate.

3. There are two factors to consider when looking at the maximum value of C. The first is

that any large value capacitors will be electrolytic and so have a leakage current which

16

must pass through R. If the leakage current is too large for the value of R then the time

period will be inaccurate. It could well happen, if there is a large leakage current, that

the voltage across C never reaches Vs and so the threshold switching voltage level is

never reached!

THE 555 ASTABLE

When first switched on the capacitor, C, is discharged and so the voltage across this

capacitor is less than the TRIGGER voltage and so the output goes to Vs. The capacitor, C,

17

charges through R1 and R2 until the voltage across C is greater than the THRESHOLD

switching level, at which point the output voltage becomes 0V and the DISCHARGE

terminal becomes connected to 0V.

The capacitor now discharges through R2 until the voltage across C becomes less

than the TRIGGER switching voltage. When this happens, the output voltage becomes Vs

and the process repeats. It should be noted that the first pulse is longer than the remainder,

since C has to charge from 0V and not Vs. The same restrictions apply to the values of C

and R (R1 and R2) as for the monostable.

CHAPTER-3

18

3.1 COMPONENT USED

3.1.1 POWER SUPPLY

1. All electronic circuits need a power source to work.

2. For electronic circuits made up of transistors and/or ICs, this power source must be a

DC voltage of a specific value.

3. A battery is a common DC voltage source for some types of electronic equipment

especially portables like cell phones and iPods.

4. Most non-portable equipment uses power supplies that operate from the AC power.

Main circuits in most power supplies.

DC Power Supply- an Introduction

19

In this section we are going to study how the AC mains supply is converted into the DC

supply required for operating many of the common electronic equipments. As you all may be

aware almost all of the electronic equipments require DC power supply for their operation.

Even those equipments to which we provide AC mains supply, convert it internally into DC

supply to power the electronic circuits

Figure 5

So, almost all electronic circuits require DC power supply and we have AC supply

commonly available in our homes, offices etc. Now, if we somehow convert the AC mains

supply to DC, then we can run our equipments using this converted DC supply.

The process of converting the AC mains supply to DC supply is called “rectification” and

the circuit used for this purpose is called “rectifier”. Using the rectifier circuit and some

other electronic components one can make a power supply to provide DC power to our

electronic equipments.

Let us now see that are those components that together with the rectifier make a complete

power supply.

20

1) Step Down Transformer

2) Rectifier Circuit

3) Filter Circuit

4) Regulator Circuit

a. Step Down Transformer

The step down transformer is used to reduce or step down the mains AC supply voltage to a

low value. The output from the step down transformer is still in the AC form, only the

voltage is reduced.

b. Rectifier Circuit

In the next section, this reduced AC voltage is fed to a rectifier circuit. The job of this

rectifier is to convert this AC supply into DC. The output of the rectifier will be a DC

supply, but it will be a pulsating DC supply, i.e. this DC supply will contain small amount of

pulses.

c. Filter Circuit.

To remove these pulses from the DC supply and to make it a clean DC supply, this pulsating

DC supply is next fed to a filter circuit. It is the job of this filter circuit to convert this DC

with pulses into a pure DC.

d. Regulator Circuit

This final DC output when given to equipment must provide a constant DC supply. But the

DC output from the filter circuit changes according to change in the load value or according

to change in the input AC mains voltage. To keep this DC output constant irrespective of

change in input AC mains voltage and the load, a circuit known as regulator circuit is used.

3.1.2 TESTING & CALIBRATION OF EQUIPMENT

21

1 Physical testing

(a) Check front panel.

(b) Check power cord.

(c) Check the cabinet.

2 Calibration

(a) Analog Voltmeter - For checking analog voltmeter regulated power supply,

Digital multimeter is used. The Digital multimeter gives accurate voltage but the

meter which connected to the equipment not gives proper accurate voltage.

(b) Analog ammeter - For checking analog ammeter regulated power supply,

Digital multimeter is used. Power supply points connected to the multi meter then

connected ammeter series with multimeter output of analog multimeter depend

upon the scale of analog ammeter.

Ammeter

22

Voltmeter of 10 v

Voltmeter of 150 v

23

3 Component Checking- All the component like resistance,capacitor,Transistor,

Diode, Continuity, Voltage, Current measure with the help of Multimeter

4 Digital Multimeter

A meter is a measuring instrument. An ammeter measures current, a voltmeter measures

the potential difference (voltage) between two points, and an ohmmeter measures

resistance. A multimeter combines these functions, and possibly some additional ones as

well, into a single instrument.

a) Multimeter as a Ammeter

1. Turn Power Off before connecting multimeter

2. Break Circuit

3. Place multimeter in series with circuit

4. Select highest current setting, turn power on, and work your way down.

5. Turn power off

6. Disconnect multimeter.

7. Reconnect Circuit POWER

Ammeter mode measures current in Amperes. To measure current you need to power off the

circuit, you need to break the circuit so that the ammeter can be connected in series. All the

current flowing in the circuit must pass through the ammeter. Meters are not supposed to

alter the behavior of the circuit, so the ammeter must have a very low resistance. The

diagrams below show the connection of a multimeter to measure current.

24

Fig:4.4(a) Multimeter as a ammeter

b) Multimeter as a Voltmeter

To use a multimeter as a voltmeter it is connected in parallel between the two points where

the measurement is to be made. The voltmeter provides a parallel pathway so it needs to be

of a high resistance to allow as little current flow through it as possible. Voltage

measurements are the most common measurements. Processing of electronic signals is

usually thought of in voltage terms. Voltage messurements are easy to do because you do not

need to change the original circuit you only need to touch the points of interests

Fig:.4.4(b) Multimeter as voltmeter

1. Select the DC or AC Volts25

2. If not a auto-ranging mutimeter then start at the highest volts scale and work your way

down.

3. Be very careful to not touch any other electronic components within the equipment and

do not touch the metal tips.

Multimeter uses

1. With the help of multimeter we can easily measure resistance

2. With the help of multimeter we can also measure the forward voltage

across the diode. With the help of multimeter we also find the terminal of transistors.

Review

. A meter capable of checking for voltage, current, and resistance is called a multimeter,

. As voltage is always relative between two points, a voltage-measuring meter

("voltmeter") must be connected to two points in a circuit in order to obtain a good reading.

Be careful not to touch the bare probe tips together while measuring voltage, as this will

create a short-circuit!

. Remember to always check for both AC and DC voltage when using a multimetercheck

for the presence of hazardous voltage on a circuit. Make sure you check for voltage between

all pair-combinations of conductors, including between the individual conductors and

ground!

26

3.1.3 LIGHT-EMITTING DIODE (LED)

A LED is a diode made from the semi-conductor material gallium arsenide

phosphide. Its component outline and symbol are shown below.

Fig: Symbol of led

When forward biased it conducts and emits light of a certain color depending on its

composition. No light emission occurs in reverse bias and if the reverse voltage exceeds

approximately 5V then the LED may be damaged.

Fig: Circuit of led

A LED requires a series resistor to ensure the current does not exceed its maximum rating,

which should be taken as 20mA.

27

3.1.4 SEVEN SEGMENT DISPLAY

Fig:5.2(d) Seven segment display

Electronic calculators, clocks, cash registers and measuring

instruments often have seven-segment LED displays as numerical indicators. Each segment

is an LED and by lighting up different segments all numbers from 0 to 9 can be displayed.

Each segment needs a separate current limiting resistor to prevent damage to the segment by

excess power dissipation.

All the cathodes (common cathode type) or all the

anodes (common anode type) are joined to form a common connection. If the driving circuit

is made from transistors, so that the seven-segment display segments are connected in the

collector circuits, then a common anode display will be required

28

3.1.5 STEPPER MOTOR

A stepper motor is an electromechanical device which converts electrical pulses into

discrete mechanical movements. The shaft or spindle of a stepper motor rotates in discrete

step increments when electrical command pulses are applied to it in the proper sequence.

The motors rotation has several direct relationships to these applied input pulses. The

sequence of the applied pulses is directly related to the direction of motor shafts rotation.

The speed of the motor shafts rotation is directly related to the frequency of the input pulses

and the length of rotation is directly related to the number of input pulses applied.

29

In addition to being classified by their step angle stepper motors are also classified

according to frame sizes which correspond to the diameter of the body of the motor. For

instance a size 11 stepper motor has a body diameter of approximately 1.1 inches. Likewise

a size 23 stepper motor has a body diameter of 2.3 inches (58 mm), etc. The body length

may however, vary from motor to motor within the same frame size classification. As a

general rule the available torque output from a motor of a particular frame size will increase

with increased body length.

30

3.1.6 ULTRASONIC SENSOR

Ultrasonic sensors (also known as transceivers when they both send and receive)

work on a principle similar to radar or sonar which evaluate attributes of a target by

interpreting the echoes from radio or sound waves respectively. Ultrasonic sensors generate

high frequency sound waves and evaluate the echo which is received back by the sensor.

Sensors calculate the time interval between sending the signal and receiving the echo to

determine the distance to an object.

31

This technology can be used for measuring: wind speed and direction (anemometer),

fullness of a tank and speed through air or water. For measuring speed or direction a device

uses multiple detectors and calculates the speed from the relative distances to particulates in

the air or water. To measure the amount of liquid in a tank, the sensor measures the distance

to the surface of the fluid. Further applications include: humidifiers, sonar, medical

ultrasonography, burglar alarms and non-destructive testing.

An ultrasonic transducer is a device that converts energy into ultrasound, or sound

waves above the normal range of human hearing. While technically a dog whistle is an

ultrasonic transducer that converts mechanical energy in the form of air pressure into

ultrasonic sound waves, the term is more apt to be used to refer to piezoelectric transducers

that convert electrical energy into sound. Piezoelectric crystals have the property of changing

size when a voltage is applied, thus applying an alternating current (AC) across them causes

them to oscillate at very high frequencies, thus producing very high frequency sound waves.

Systems typically use a transducer which generates sound waves in the ultrasonic

range, above 18,000 hertz, by turning electrical energy into sound, then upon receiving the

echo turn the sound waves into electrical energy which can be measured and displayed.

The technology is limited by the shapes of surfaces and the density or consistency of

the material. For example foam on the surface of a fluid in a tank could distort a reading.

32

3.1.7 LM78XX (SERIES VOLTAGE REGULATORS)

GENERAL DESCRIPTION

The LM78XX series of three terminal regulators is available with several fixed

output voltages making them useful in a wide range of applications. One of these is local on

card

regulation, eliminating the distribution problems associated with single point regulation. The

voltages available allow these regulators to be used in logic systems, instrumentation, HiFi,

and other solid state electronic equipment. Although designed primarily as fixed voltage

regulators these devices can be used with external components to obtain adjustable voltages

and currents.

The LM78XX series is available in an aluminum TO-3 package which will allow

over 1.0A load current if adequate heat sinking is provided. Current limiting is included to

limit the peak output current to a safe value. Safe area protection for the output transistor is

provided to limit internal power dissipation. If internal power dissipation becomes too high

for the heat sinking provided, the thermal shutdown circuit takes over preventing the IC from

overheating.

Considerable effort was expanded to make the LM78XX series of regulators easy to

use and minimize the number of external components. It is not necessary to bypass the

output, although this does improve transient response. Input bypassing is needed only if the

regulator is located far from the filter capacitor of the power supply. For output voltage other

than 5V, 12V and 15V the LM117 series provides an output voltage range from 1.2V to

57V.

3.10.2 Features

1.Output current in excess of 1A

2.Internal thermal overload protection

3.No external components required

4.Output transistor safe area protection

5.Internal short circuit current limit

6.Available in the aluminum TO-3 package

33

Voltage Range

LM7805C 5V

LM7812C 12V

LM7815C 15V

Connection diagram:

.4electing the Best Regulator For Your Application

The best choice for a specific application can be determined by evaluating the

requirements such as:

Maximum Load Current

Type of Input Voltage Source (Battery or AC)

Output Voltage Precision (Tolerance)

Quiescent (Idling) Current

Special Features (Shutdown Pin, Error Flag, etc.)

34

3.1.8 PCB LAYOUT

Printed Circuit Boards (PCB) are used to both mechanically support and electrically

connect electronic components by either surface mount (SMT) or though hole assembly

using conductive pathways, or traces, etched from copper sheets laminated onto a non-

conductive substrate.

Alternative names are:

Printed wiring board's (PWB)

Etched wiring board

Switchboard

After populating the board with electronic components, a printed circuit assembly

(PCBA) is formed. This PCBA subassembly will become an integral layer in a GGI

manufactured User Interface Assembly.

35

3.1.9 RESISTORS

Resistors determine the flow of current in an electrical circuit. Where there is high

resistance in a circuit the flow of current is small, where the resistance is low the flow of

current is large. Resistance, voltage and current are connected in an electrical circuit

by Ohm’s Law.

Resistors are used for regulating current and they resist the current flow and the

extent to which they do this is measured in ohms (Ω). Resistors are found in almost every

electronic circuit.

The most common type of resistor consists of a small ceramic (clay) tube covered

partially by a conducting carbon film. The composition of the carbon determines how much

current can pass through.

Resistors are too small to have numbers printed on them and so they are marked with

a number of coloured bands. Each colour stands for a number. Three colour bands show the

resistors value in ohms and the fourth shows tolerance. Resistors can never be made to a

precise value and the tolerance band (the fourth band) tells us, using a percentage, how close

the resistor is to its coded value.

36

RESISTOR COLOUR CODING

The resistor color code is a long standing standard in both the electronics and

electrical industries, indicating the value of resistance of a resistor. Resistance is measured

in ohms and there is a foundation for it called Ohm's Law. (Want to know about Ohm's Law?

If so, Each color band represents a number and the order of the color band will represent a

number value. The first 2 color bands indicate a number. The 3rd color band indicates the

multiplier or in other words the number of zeros. The fourth band indicates the tolerance of

the resistor +/- 20%, 10% or 5%. In most cases, there are 4 color bands. However, certain

precision resistors have 5 bands or have the values written on them, refining the tolerance

value even more. There is no standard (TANS) however, for the 5th band. From one

manufacturing company to another, the 5th band may indicate 2%, 1%, 1/2% or even closer,

according to their own standards. Color bands are usually found on resistors that have a

wattage value of 1/8 to 2 watts; though it is rare, there are some 5 watt resistors that are

banded. There are also some capacitors that are color coded.

37

COLOUR CODING TABLE

38

3.1.10 TRANSISTORS

A transistor is a semiconductor device used to amplify and switch electronic signals

and power. It is composed of a semiconductor material with at least three terminals for

connection to an external circuit. A voltage or current applied to one pair of the transistor's

terminals changes the current flowing through another pair of terminals. Because the

controlled (output) power can be much more than the controlling (input) power, a transistor

can amplify a signal. Today, some transistors are packaged individually, but many more are

found embedded in integrated circuits.

The transistor is the fundamental building block of modern electronic devices, and is

ubiquitous in modern electronic systems. Following its release in the early 1950s the

transistor revolutionized the field of electronics, and paved the way for smaller and

cheaper radios, calculators, and computers, among other things.

The essential usefulness of a transistor comes from its ability to use a small signal

applied between one pair of its terminals to control a much larger signal at another pair of

terminals. This property is called gain. A transistor can control its output in proportion to the

input signal; that is, it can act as an amplifier. Alternatively, the transistor can be used to turn

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current on or off in a circuit as an electrically controlled switch, where the amount of current

is determined by other circuit elements.

There are two types of transistors, which have slight differences in how they are used

in a circuit. A bipolar transistor has terminals labeled base, collector, and emitter. A small

current at the base terminal (that is, flowing from the base to the emitter) can control or

switch a much larger current between the collector and emitter terminals. For a field-effect

transistor, the terminals are labeled gate, source, and drain, and a voltage at the gate can

control a current between source and drain.

The image to the right represents a typical bipolar transistor in a circuit. Charge will

flow between emitter and collector terminals depending on the current in the base. Since

internally the base and emitter connections behave like a semiconductor diode, a voltage

drop develops between base and emitter while the base current exists. The amount of this

voltage depends on the material the transistor is made from, and is referred to as VBE.

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3.1.11 CAPACITORS

Capacitors are components that are used to store an electrical charge and are used in

timer circuits. A capacitor may be used with a resistor to produce a timer. Sometimes

capacitors are used to smooth a current in a circuit as they can prevent false triggering of

other components such as relays. When power is supplied to a circuit that includes a

capacitor - the capacitor charges up. When power is turned off the capacitor discharges its

electrical charge slowly.

A capacitor is composed of two conductors separated by an insulating material called

a DIELECTRIC. The dielectric can be paper, plastic film, ceramic, air or a vacuum. The

plates can be aluminum discs, aluminum foil or a thin film of metal applied to opposite sides

of a solid dielectric. The CONDUCTOR - DIELECTRIC - CONDUCTOR sandwich can be

rolled into a cylinder or left flat

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Electrolytic capacitors are ‘polarized’ which means they have a positive and negative

lead and must be positioned in a circuit the right way round (the positive lead must go to the

positive side of the circuit). They also have a much higher capacitance than non-electrolytic

capacitors.

Non-electrolytic capacitors usually have a lower capacitance. They are not polarized

(do not have a positive and negative lead) and can be placed anyway round in a circuit.

They are normally used to smooth a current in a circuit.

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CAPACITOR CODING

There is a three digit code printed on a ceramic capacitor specifying its value. The

first two digits are the two significant figures and the third digit is a base 10 multiplier. The

value is given in picofarads (pF). A letter suffix indicates the tolerance.

C ± 0.25 pF M ±20%

D ± 0.5 pF P +100 −0%

J ± 5% Y −20 +50%

K ±10% Z −20 + 80%

Example: a label of "104K" indicates 10×104 pF = 100,000 pF = 100 nF = 0.1 µF ±10%

3.1.12 IC SOCKET

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Socketing expensive IC’s or holding the firmware during the debugging phase of a

new design is not only advisable, for most applications mandatory. The Adapters.com sales

staff has over 50 years combined experience working with IC packaging and there

applications. In some cases we know the product better than the manufactures themselves. It

is mainly used for IC safety.

CHAPTER-444

4.1 TOOLS USED

4.1.1 SOLDERING IRON

A soldering iron is a hand tool most commonly used in soldering. It supplies heat to

melt the solder so that it can flow into the joint between two workpieces.

A soldering iron is composed of a heated metal tip and an insulated handle. Heating

is often achieved electrically, by passing an electric current (supplied through an electrical

cord or battery cables) through the resistive material of a heating element. Another heating

method includes combustion of a suitable gas, which can either be delivered through a tank

mounted on the iron (flameless), or through an external flame.

Less common uses include pyrography (burning designs into wood) and plastic

welding.

Soldering irons are most often used for installation, repairs, and limited production

work. High-volume production lines use other soldering methods.

4.1.2 SOLDERING STAND

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A soldering iron stand keeps the iron away from flammable materials, and often

also comes with a cellulose sponge and flux pot for cleaning the tip. Some soldering

irons for continuous and professional use come as part of a soldering station, which

allows the exact temperature of the tip to be adjusted, kept constant, and sometimes

displayed.

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4.1.3 SOLDER WIRE

Solder is a fusible metal alloy used to join together metal workpieces and having a

melting point below that of the workpiece(s).

Soft solder is what is most often thought of when solder or soldering are mentioned

and it typically has a melting range of 90 to 450 °C (190 to 840 °F). It is commonly used

in electronics and plumbing. Alloys that melt between 180 and 190 °C (360 and 370 °F) are

the most commonly used. By definition, using alloys with melting point above 450

°C (840 °F) is called 'hard soldering', 'silver soldering' or brazing. Soft solder can contain

lead and/or flux but in many applications lead free solder is used. Perhaps the most common

and most familiar form of solder is as a wire or rod, though plumbers often use bars of solder

while jewelers often use solder in thin sheets which they cut into snippets. Solder can also

come in a paste or as a preformed foil shaped to match the workpiece. The word solder

comes from the Middle English word soudur, via Old French solduree and soulder, from

the Latin solidare, meaning "to make solid".

Eutectic alloys melt at a single temperature. Non-eutectic alloys have markedly

different solidus and liquidus temperature, and within that range they exist as a paste of solid

particles in a melt of the lower-melting phase. The pasty state causes some problems during

handling; it can however be exploited as it allows molding of the solder during cooling, e.g.

for ensuring watertight joint of pipes, resulting in a so called 'wiped joint'.

With the reduction of the size of circuit board features, the size of interconnects

shrinks as well. At such current densities the Sn63Pb37 solder balls form hillocks on the

anode side and voids on the cathode side; the increased content of lead on the anode side

suggests lead is the primary migrating species.

.

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CHAPTER-5

5.1 CLEANING

When burnt flux and oxidized material begin to accumulate on the tip, they can block

heat transfer and contaminate joints, making soldering difficult or impossible. Therefore, the

tips are periodically cleaned. Many soldering stations come with cellulose sponges which are

dampened and used to wipe a hot iron's tip clean. A wire brush, preferably brass or wire

wheel (mounted on a bench grinder), is sometimes carefully used to remove very severe

oxidation, though this may risk damaging the tip's protective iron plating. A small amount of

fresh solder is usually then applied to the clean tip in a process called tinning. The working

surface of the tip is usually kept tinned (coated with wet solder) to minimize oxidation.

Oxidation blocks heat transfer, corrodes the tip, and contaminates the joint.

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5.2 TIPS

Some soldering irons have interchangeable tips, also known as bits that vary in size

and shape for different types of work. Pyramid tips with a triangular flat face and chisel tips

with a wide flat face are useful for soldering sheet metal. Fine conical or tapered chisel tips

are typically used for electronics work.

Older and very cheap irons typically use a bare copper tip, which is shaped with a file

or sandpaper. This dissolves gradually into the solder, suffering pitting and erosion of the

shape. Copper tips are sometimes filed when worn down. Iron-plated copper tips have

become increasingly popular since the 1980s. Because iron is not readily dissolved by

molten solder, the plated tip is more durable than a bare copper one. This is especially

important when working at the higher temperatures needed for modern lead-free solders.

Solid iron and steel tips are seldom used because they store less heat, and rusting can break

the heating element.

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5.3 PCB PREPARATION

1. CLEANING OF PCB- The plate of copper is generally washed so as to remove an

oxide grease or dirt.

2. DESINGNING- Draw the layout of the circuit on the graph paper. The distance for

the component is left by placing the component.

3. PAINTING- Once the layout circuit is drawn, we will paint the PCB. Draw lines on

PCB with the help of brush. Lines should neither be too narrow nor be too wide.

4. ETCHING- For etching of the plates take a utensil and wash it properly. For washing

PCB take water, just enough to complete immerse the board. Add 230 gm of ferric chloride

carefully without splashing and place the PCB. Place the plate in utensil with the copper side

up such that the copper side is completely immersed in solution. After sometime the copper

side etches and the base material could not thus, the etching process is completed.

5. DRILLING - When the paint is dry, we should drill the plate. The holes should be

exactly placed so that the component fix exactly in the holes without any bending of leads.

For the drilling of holes, place it on the proper position. Always ensure that the copper lines

passage near the holes.

6. WASHING - The paint of pattern is removed by rubbing it with rag to see the entire

copper pattern. Now wash the PCB in water.

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CHAPTER 6

6.1 TESTING

6.1.1 BREADBOARD TESTING

Each board needs to ensure that the required connection exists, that there are not

short circuit and drill holes are properly placed. The testing usually consists of visual

inspection and continuity testing, Complex board requires both.

6.1.2 VISUALIZATION TESTING

All the components have been mounted we inspect that they have been mounted

according to the layout and circuit diagram. Then soldering is done. The circuit is then

checked for any soldering defects or short circuiting.

6.1.3 OVERHEATING TESTING

The circuit is switched on and then kept on for several hours to check for burning of

any component especially IC. This helps us to know the consistency of the circuit.

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CONCLUSION

The dynamic interaction between epistemological (instruments and techniques)

concerns and the kinds of problems radar astronomers seek to solve, which we have seen

driving planetary radar astronomy to the present, also in all likelihood will continue to

determine its future. Both new instruments and techniques will furnish the means for

exploring new targets and for resolving problems, especially those left unresolved or

unsatisfactorily resolved by optical means.

Planetary radar techniques developed recently perhaps hint at the sources of future

techniques. Three examples are John Harmon's non-repeating code, which he adapted from

Arecibo ionospheric research; Dewey Muhleman's use of radio astronomy imaging and

arraying techniques at the VLA, as part of the bistatic Goldstone-VLA radar; and the

planetary imaging technique developed by Scott Hudson and Steve Ostro. The Harmon and

Muhleman techniques reflect the continuing, though diminished, influence of ionospheric

research and radio astronomy on planetary radar astronomy

In many ways, then, planetary radar astronomy has come full circle. It began with the

study of large populations of meteors, and the observation and analysis of the large and

varied asteroid population is carrying it into the future. Forty years ago, the forte of radar lay

in its ability to determine accurately the radiants and speed of meteors and to ascertain

unambiguously that they orbited around the Sun. Today, the value of radar is its ability to fix

asteroid orbits with an accuracy and certainty that no other method can match.

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RESULT

Study of ultrasonic radar has been completed.

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REFERENCES

1. Digital electronics-R.P.Jain.

2. Electronics devices and circuits-Sanjeev Gupta.

3. Digital electronics-Floyd.

4. http://www. wikepedia.org.

5. http://www.circuitstoday.com/200m-fm-transmitter/

6. http://www.members.tripod.com/~transmitters/

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