ultrasonic radar
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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.
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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.
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1.1.5 CIRCUIT DIAGRAM OF ULTRASONIC RADAR
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1.1.6 PCB LAYOUT OF ULTRASONIC RADAR
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CHAPTER 2
2.1 IC USED
2.1.1 PIN DIAGRAM OF HEF4017BMSI
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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.
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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
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5 STAGE JOHNSON COUNTER
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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.
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2.1.2 PIN DIAGRAM OF 555 TIMER IC
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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
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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,
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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
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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
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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.
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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
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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
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Voltmeter of 10 v
Voltmeter of 150 v
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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.
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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!
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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.
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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
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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.
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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.
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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.
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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.
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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
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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.)
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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.
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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.
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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.
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COLOUR CODING TABLE
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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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