ACKNOWLEDGEMENTI would like to express my sincere, humble and
deep sense of gratitude to Mr. J.P. Sharma for his invaluable
guidance, help, encouragement, & criticism along with his
valuable experiences which he gained by various projects,
industrial work. This work could not have been completed without
his constant guidance and advice. His perception and devotion to
quality work has inspired me a lot.I would like to extend my
gratitude to the people who helped me a lot during my project work.
I am highly thankful to Mr. J.P.Sharma for providing useful
suggestions and information.I would also like to thank Mr.
J.P.Sharma.I appreciate the cooperation extended to me by the
teaching and teaching supporting staff members of Department of
Electronics & Communication Engineering, I apologize to those
whose help is not acknowledged.
Jitender kumarShiv Kumar SainiSushil Kumar
INTRODUCTION
A motion detector is a kind of security system that uses sensing
ability in the form of sensors to detect movement and and this
usually triggers an alarm, or sometimes activate another circuit.
However, motion detectors are normally used to protect indoor
areas, in this, conditions can then be controlled more closely.
Detectors for use in homes for security purpose usually detect
movement in a closed space area of little feet-by-feet. Detectors
for large range warehouses can protect areas with dimensions as
large as 24mx37m . The motion detector is normally useful in places
like museums where important assets are located. As such, motion
detectors can detect break-in at vulnerable points. Such points
include walls, doors windows and other openings. Special motion
detectors can protect the inside of exhibit cases where items such
as diamonds arc placed. Others can be focused on a narrow area of
coverage, somewhat like a curtain, that projected in front of a
painting to detect even the slightest touch.Motion detector systems
use a variety of methods to detect movement. Each method has
advantages and disadvantages. Motion detectors can be categorized
into two major types these are namely: (1) Passive detectors. (2)
Active detectors. Passive detectors are detectors which do not send
out signals but merely receive signals, such as change in
temperature, change in light intensity and so on. Most infrared
detectors are passive detectors. While Active detectors are
detectors which send out waves of energy and receive waves
reflected back from objects. Any disturbance in the reflected waves
caused by example a moving object will trigger an alarm. Microwave
and ultrasonic detectors are examples of active detectors. Man and
animal or moving object produces sound. The sound is created as a
result of their physical movement, which might be low or fast
movement, and also depends on the medium that create the sound.
However, these movements can be detected by using an ultrasonic
sensor. The ultrasonic sound waves are sound waves that are above
the range of human hearing and, thus, have a frequency above about
20khz. Any frequency of above 20kz is considered ultrasonic . In
general, an ultrasonic sensor typically comprises of one or more
ultrasonic transducer which transforms electrical energy into sound
and vice-versa, a casing which encloses the ultrasonic transducer,
connectors, and if possible some electronic circuit for signal
processing. Nowadays there are numerous of the commercial
ultrasonic motion detectors, basically the main aim of this work is
to design and construct a simple and cheap ultrasonic motion
detector system which is aimed at detecting the physical movement
of human, animal, or anything that moves. The design is to improve
the use of sensor in detecting motion. In general, it is aimed at
reduction of the cost to design, develop or construct an ultrasonic
motion detector. Human, animal or anything can produce sound. This
sound is creating by the physical movement whether the movement is
fast or slow depends on the medium that create the sound.
Eventually these movements can be detected by using an ultrasound
sensor. Ultrasonic sound waves are sound waves that are above the
range of human hearing and, thus, have a frequency above about
20,000 hertz. Any frequency above 20,000 hertz may be considered
ultrasonic. An ultrasonic sensor typically comprises at least one
ultrasonic transducer which transforms electrical energy into sound
and, in reverse, sound into electrical energy, a housing enclosing
the ultrasonic transducer or transducers, an electrical connection
and, optionally, an electronic circuit for signal processing also
enclosed in the housing. Ultrasonic sensors have typically been
used in applications such as detecting and identifying solid
objects, measuring the shape and orientation of a work piece,
detecting possible collisions between objects to avoid the
collisions, room surveillance, flow measurement, and determining a
type of material by measuring the absorption of sound. By combining
parts of electronic to the ultrasonic sensor it become an
ultrasonic motion detector. A motion detector is an electronic
device that detects the physical movement in a given area and
transforms motion into an electric signal. The motion detector may
be electrically connected to devices such as security, lighting,
audio 2 alarms. Motion sensors are usedin a wide variety of
applications. Motion detectors are mainly used in for security
systems.Now days in the market there are many kind of ultrasonic
motion detector sell, basically this project is to design an
ultrasonic motion detector use to detect physical movement of
human, animal, or anything that move. The design is to improving
the use of sensor in detecting motion. Also to reduce the cost to
built an ultrasonic motion detectorProject name:- ULTRA SONIC
SENSER CIRCUITUltrasonic sensors use sound waves rather than light,
making them ideal for stable detection of uneven surfaces, liquids,
clear objects, and objects in dirty environments. These sensors
work well for applications that require precise measurements
between stationary and moving objects. Overview:-
Inexpensive motion detector used to control lightingAn
electronic motion detector contains an optical, microwave, or
acoustic sensor, and in many cases a transmitter for illumination.
However, apassivesensor only senses a signal emitted by the moving
object itself. Changes in the optical, microwave, or acoustic field
in the device's proximity are interpreted by the electronics based
on one of the technologies listed below. Most inexpensive motion
detectors can detect up to distances of at least 15 feet (5
meters). Specialized systems are more expensive but have much
longer ranges. Tomographic motion detection systems can cover much
larger areas because the radio waves are at frequencies which
penetrate most walls and obstructions, and are detected in multiple
locations, not just at the location of the transmitter.Motion
detectors have found wide use in domestic and commercial
applications. One common application is activation of automatic
door openers in businesses and public buildings. Motion sensors are
also widely used in lieu of a trueoccupancy sensorin activating
street lights or indoor lights in walkways (such as lobbies and
staircases). In such "Smart Lighting" systems, energy is conserved
by only powering the lights for the duration of a timer, after
which the person has presumably left the area. A motion detector
may be among the sensors of aburglar alarmthat is used to alert the
home owner or security service when it detects the motion of a
possible intruder. Such a detector may also trigger asecurity
camerain order to record the possible intrusion. Sensor
technology:-
Infrared detector mounted on circuit board, along with
photoresistive detector for visible light .There are several motion
detection technologies in wide use.Passive infrared (PIR)Passive
infrared sensors are sensitive to a person's skin temperature
through emittedblack body radiationatmid-infraredwavelengths, in
contrast to background objects at room temperature. No energy is
emitted from the sensor, thus the name "passive infrared" (PIR).
This distinguishes it from theelectric eyefor instance (not usually
considered a "motion detector"), in which the crossing of a person
or vehicle interrupts a visible or infrared beam.Microwave:-These
detect motion through the principle of Dopplerradar, and are
similar to aradar speed gun. Acontinuous waveofmicrowave radiation
is emitted, and phase shifts in the reflected microwaves due to
motion of an object toward (or away from) the receiver result in
aheterodynesignal at lowaudio frequencies.Ultrasonic:-An ultrasonic
wave (sound at a frequency higher than a human can hear) is emitted
and reflections from nearby objects are received. Exactly as in
Doppler radar, heterodyne detection of the received field indicates
motion. The detecteddoppler shiftis also at low audio frequencies
(for walking speeds) since the ultrasonicwavelength of around a
centimeter is similar to the wavelengths used in microwave motion
detectors. One potential drawback of ultrasonic sensors is that the
sensor can be sensitive to motion in areas where coverage isn't
desired, for instance, due to reflections of sound waves around
corners.Such extended coverage may be desirable for lighting
control, where the point is detection of any occupancy in an area.
But for opening an automatic door, for example, one would prefer a
sensor selective to traffic in the path toward the door.Tomographic
motion detectorTomographic motion detection systems sense
disturbances to radio waves as they pass from node to node of a
mesh network. They have the ability to detect over complete areas
because they can sense through walls and obstructions.Video camera
software With the proliferation of inexpensivedigital
camerascapable of shooting video, it is possible to use the output
of such a camera to detect motion in its field of view using
software. This solution is particularly attractive when the
intention was to record video triggered by motion detection, as no
hardware beyond the camera and computer is required. Since the
observed field may be normally illuminated, this may be considered
anotherpassivetechnology. However it can also be used in
conjunction withnear-infraredillumination to detect motion in the
"dark" (that is, with the illumination at a wavelength not detected
by the human eye)
2. ULTRASONIC MOTION DETECTORS:-
Generally, there exist numerous of motion detector, but of our
interest is the ultrasonic motion detectors due to its numerous
advantage over other types of detectors. For example, having fast
response time and very sensitive, no physical contact required by
the object, being environmentally friendly and reliable, and above
all utilizing ultrasonic waves that are not visible and audible to
human. Ultrasonic motion detectors are electrical devices, which
use ultra-sound (that is, sound of very high frequency) to detect
motion. In such a detector a transmitter emits a sound of a
frequency which is normally too high for the human ear to hear.
When a receiver picks up the sound waves that is reflected from the
area under protection, it sends it to an appropriate circuit for
further action (normally an audio circuit). In the case of motion
of human or target in the space between the receiver and
transmitter, further change, or shift in the frequency of sound is
experienced , a circuit in the device detects any unusual shift in
frequency, which is normally noted due to predefined frequency. A
small shift in frequency, such as that produced by an insect or
rodent, is ignored. When a noticeable shift is observed, such as a
large shift produced by a moving person, the device triggers the
alarm. HISTORY:-observing Prior to World War II, sonar, the
technique of sending sound waves through water and the returning
echoes to characterize submerged objects, inspired early ultrasound
investigators to explore ways to apply the concept to medical
diagnosis. In 1929 and 1935, Sokolov studied the use of ultrasonic
waves in detecting metal objects. Mulhauser, in 1931, obtained a
patent for using ultrasonic waves, using two transducers to detect
flaws in solids. Firestone (1940) and Simons (1945) developed
pulsed ultrasonic testing using a pulse-echo technique. Shortly
after the close of World War II, researchers in Japan began to
explore the medical diagnostic capabilities of ultrasound. The
first ultrasonic instruments used an A-mode presentation with blips
on an oscilloscope screen. That was followed by a B-mode
presentation with a two dimensional, gray scale image. Japan's work
in ultrasound was relatively unknown in the United States and
Europe until the 1950s. Researchers then presented their findings
on the use of ultrasound to detect gallstones, breast masses, and
tumors to the international medical community. Japan was also the
first country to apply Doppler ultrasound, an application of
ultrasound that detects internal moving objects such as blood
coursing through the heart for cardiovascular investigation.
Ultrasound pioneers working in the United States contributed many
innovations and important discoveries to the field during the
following decades. Researchers learned to use ultrasound to detect
potential cancer and to visualize tumors in living subjects and in
excised tissue. Real-time imaging, another significant diagnostic
tool for physicians, presented ultrasound images directly on the
system's CRT screen at the time of scanning. The introduction of
spectral Doppler and later color Doppler depicted blood flow in
various colors to indicate the speed and direction of the flow..
The United States also produced the earliest hand held "contact"
scanner for clinical use, the second generation of B-mode
equipment, and the prototype for the first articulated-arm hand
held scanner, with 2-D images.
How the ultrasonic sensor works?
The ultra sonic 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 circuit works from 9-12 VDC and can be used with
batteries or a power supply.ULTRASONIC MOTION DETECTOR:-The
ultrasonic motion detector is a project that uses an ultrasonic
sensor as its base to detect movement or moving object in small
places. It is design to be a low cost ultrasonic motion detector.
The transmitter sensor use to generate signal in that area. When
the signal is block by moving or movement the receiver will gets
the signal and amplifies the signal using transistor. The
transistor is use as an amplifier to the receiver circuit. The Led
and buzzer in the circuit use to see if there is movement detect by
the sensor. The relay use to trigger another circuit when there is
movement detects. The signal generate by the sensor is about 40khz.
This is a fully hardware design project plus it is built to be a
portable ultrasonic motion detector. The circuit consists of the
following major blocks.1. Transmitter 2. Receiver3. Transistor
Amplifier Circuit4. Op amp Amplifier5. Op amp Comparator 6. Pi
Filter7. Schmitt Trigger8. Darlington pair Amplifier Block
Diagram:-Before starting with actual circuit design, we must first
understand the basic principles behind the technology that is used
this project. The project methodology flow chart is shown below
Figure 3.1 Flow design of the circuitThe flow design of the
circuit consist of
1. Finding the right transmitter and receiver sensor for the
circuit.
2. Designing the amplifier/receiver circuit
3. Design the transmitter circuit
4. Using simulation to verify the design.
5. Implementation on board.
Figure:- Block Diagram of ultrasonic Sensor CircuitBlock diagram
description:-Ultrasonic sensor consist the following circuit in
block diagram.1. Amplifier circuit.2. Hex buffer circuit 3. Sensor
circuit.Amplifier circuit For the amplifier in this project, the
transistor is use to act as amplifier. The basic transistor
amplifier circuit is use act as an amplifier method to amplifying.
H9013 series of transistor is use because the transistor is the
general transistor use in amplifying concept. It is a BJT type of
transistor. When the receiver sensor receive signal it will send
the signal to the transistor to be amplified. In this project five
transistors is use to amplified the signal send by the receiver
sensor. The type of design for the transistor is a common emitter
amplifier. Base from the design the input signal that come from the
base of transistor will be amplified and produce at the collector
transistor a larger output signal and the output will be more on
positive side signal. Mean that the transistor will amplify current
from a small input current to a high output current. It is use also
to trigger the relay connected to it. Variable resistor is use to
control the level of signal or the sensitivity signal send by the
receiver sensor. Mean if no setting are made by the variable
resistor the sensor is highly sensitive, even the air counts as a
motion parts thus we will get false trigger by the circuit.
Figure:- Basic design of amplifers.
Hex buffer circuit
This circuit consist a buffer, crystal and transmitter sensor in
it. The crystal is use to drive the transmitter sensor into a
steady frequency stability. It will ring the transmitter to
continuous transmitting frequency. A voltage applied across the
crystal will cause mechanical movement within the crystal. If an AC
voltage is applied across the crystal, the crystal will begin to
vibrate. Thus in this circuit it the buffer act as a driver to make
sure that the sensor transmit the frequency. The crystal or XTAL is
a 40 kHz in frequency. The buffer or hex inverter use in the
circuit is single supplies IC mean single supply needed to make it
work. It is use to change from high to low level logic conversion.
The IC is HD4069UBP hex buffer converter. The supply can be 9Vdc or
12Vdc. It is 14 pin IC. In this project the pin 1 until pin 6 uses
for the transmitter sensor to drive the frequency, the other pin
use to drive transistor to supply enough current for the relay to
energize.
Figure:- Top view of HD4069UBP buffer IC.
.
Figure:- Transmitter Circuit Design
Sensor circuit (Transmitter and Receiver):-
Use to transmit and receive signal and send to the circuit. The
sensor in this circuit is an ultrasonic sensor. The frequency
generate by the sensor 40kHz. The transmitter and receiver must be
equal in frequency to make the circuit function. When power supply
is given to the circuit, the transmitter will transform the
electrical energy to sound wave and transmit it to the air. Thus
when the sound wave or signal is blocking by something or someone,
the signal will be detected by the receiver. Crucial thing is
finding the right sensor for the right circuit. Moreover the sensor
cannot be place to far from each other.
Fiqure:- Sensor (Transmitter and Receiver)
Ultra Sonic Detector ConstructionThe 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. In order to solder a component correctly you should
do the following. Clean the component leadswith a small piece of
emery paper. Bend them at the correct distancefrom the components
body and insert the component in its place on the board. You may
find sometimes a component with heavier gauge leadsthan 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
leadwhile 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
flowwait 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 overheatthe tracks
as it is very easy to lift them from the board and break them. When
you are soldering a sensitive componentit 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 solderthan 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 offthe 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. There are quite a
few components in the circuitand 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
diodestaking 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
ICs 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 aluminium 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 (point1).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.
Figure:- Ultra Sonic Motion Detector Circuit
Figure:-Circuit Diagram Of Ultra Sonic Motion Detector
The circuit consists of the following component1. Transmitter.
2. Receiver.3. Transistor Amplifier Circuit.4. Op amp Amplifier. 5.
Op amp Comparator. 6. Pi Filter.7. Schmitt Trigger.8. Darlington
pair Amplifier.9. Resistor.10. Capacitor.11. IC circuit.12.
Transducer.13. Diode.14. Sensor (Transmitter and Receiver).
Figure:- Component used in Ultrasonic sensor circuit.
Transmitter:-
Inelectronicsandtelecommunicationsatransmitterorradio transmitteris
anelectronic devicewhich, with the aid of anantenna, producesradio
waves. The transmitter itself generates aradio frequencyalternating
current which is applied to the antenna. When excited by this
alternating current, the antenna radiatesradio waves. In addition
to their use inbroadcasting, transmitters are necessary component
parts of many electronic devices that communicate byradio, such
ascell phones,wireless computer networks bluetoothenabled
devices,garage door openers,two-way radios in aircraft, ships, and
spacecraft,radarsets, and navigational beacons. The transmitter
circuit consists of mainly an astable multivibrator circuit using
IC 4093. The capacitor and resistor values are adjusted to obtain a
frequency of 40 kHz which is fed to the ultrasonic transmitter. The
transmitter produces ultrasonic waves of 40 kHz frequency which
travel around the room, get reflected and fall on the receiver.U2C
forms a 40 KHz oscillator. This oscillator is connected to U2D and
U2E while the inverted oscillator signal (U2B) goes to U2A and U2F.
These parallel gates provide more current and drive the ultrasonic
transmitter. Note that it may take a couple of seconds after the
power is applied for the oscillator to stabilize.Figure:-
Ultrasonic Transmitter.Receiver:- Ultrasonic Receiver which will
detect the signal from the Ultrasonic Transmitter once it bounces
off from an object. The combination of these two sensors will allow
the aerial robot to detect objects in its path and maneuver around
the objects. These sensors will be attached in front of the
plane.OR The receiver is an ultrasonic transducer. After
transmission, the signal gets reflected from the surroundings. This
signal is received at the receiver transducer and is then sent to
process for the presence of motion. Q1 and Q2 amplify the reflected
40 KHz signal picked up by the ultrasonic receiver by 2500. Q2 is
capacitively coupled to the voltage doubler formed by D1 and D2.
The rectified signal is connected to the negative input of voltage
comparator U1A. R12 (the Sensitivity potentiometer) sets the
threshold voltage for U1A. When the threshold voltage is exceeded,
the open collector output of U1A goes high-impedance. This enables
the 70 Hz oscillator formed by U1B.When this oscillator is on, the
LED glows and the one-shot formed by U3 is repeatedly triggered.
The output duration of the one-shot is set by R16 and C11 and is
equal to 1.1*R16*C11 seconds. U3's output turns on Q3. As a result,
K1 closes its normally open contacts. C13 dampens the inductive
kickback when K1 is turned off, preventing the circuit from
triggering due to this noise source. The unit is powered by a 12
VDC 200mA unregulated wall transformer. U4 provides a regulated
9VDC to power the circuit. Device pinouts are shown in Figure 2.
The 40 KHz transmitter and receiver are mounted 4" apart on a piece
of perfboard.
Figure:- Ultrasonic Transmitter and Reciver.
Figure:- Ultrasonic Reciver.Resistor:- Aresistoris
apassivetwo-terminalelectrical componentthat implements electrical
resistanceas a circuit element. Resistors act to reduce current
flow, and, at the same time, act to lower voltage levels within
circuits. In electronic circuits resistors are used to limit
current flow, to adjust signal levels,biasactive elements,
terminatetransmission linesamong other uses. In the ultrasonic
sensor circuit many resistors are used.Name of the resistor which
are used in ultrasonic sensor circuit is below.1. R1= 180kohm2.
R2=12kohm3. R3,R8=47kohm4. R4=9kohm5. R5,R6,R16=10kohm6.
R7,R10,R12,R14,R17=100kohm7. R9,R11=1mohm8. R13,R15=3mohm
Figure:- Circuit Layout of Sensor
These are those resistor which are mainly used in ultrasonic
sensior circuit.Acapacitor(originally known as acondenser) is
apassivetwo-terminalelectrical componentused to
storeenergyelectrostaticallyin anelectric field. The forms of
practical capacitors vary widely, but all contain at least
twoelectrical conductors(plates) separated by adielectricinsulaton.
The conductors can be thin films, foils or sintered beads of metal
or conductive electrolyte, etc. The nonconducting dielectric acts
to increase the capacitor's charge capacity. A dielectric can be
glass, ceramic, plastic film, air, vacuum, paper, mica, oxide layer
etc. Capacitors are widely used as parts ofelectrical circuitsin
many common electrical devices. Name of the resistor which are used
in ultrasonic sensor circuit is below.1. C1=10uf/16v2.
C2=47uf/16v3. C3=4,7pf4. C4,C7=1nf5. C5=10nf6. C8,C11=4,7uf/16v7.
C9=22uf/16v8. C10=100nf9. C12=2,2uf/16v10. C13=3,3nf11.
C14=47nfThese are the those capacitor which is used in ultrasonic
sensor.
Figure:- CapacitorIC CIRCUIT:-Anintegrated circuitormonolithic
integrated circuit is a set ofelectronic circuiton one small plate
("chip") ofsemiconductor material, normallysilicon. This can be
made much smaller than adiscret circuit made from
independentelectronic components. ICs can be made very compact,
having up to several billiontransistorsand other electronic
componentsin an area the size of a fingernail.
Figure:-Motion Sensor CircuitTransistor Amplifier Circuit
The first part of the receiver circuit consists of an amplifier
section using a BC547. The ultrasonic waves from the transmitter
get reflected and fall on the receiver. The receiver is connected
to an amplifier circuit having a gain of 20. The amplitude of waves
falling on the receiver is very small, the amplifier amplifies the
noise.Op-amp Amplifier:- Anoperational amplifier("op-amp") is
aDC-coupledhigh-gainelectronic voltageamplifierwith adifferential
inputand, usually, a single-ended output.In this configuration, an
op-amp produces an output potential (relative to circuit ground)
that is typically hundreds of thousands of times larger than the
potential difference between its input terminals.Operational
amplifiers had their origins inanalog computers, where they were
used to do mathematical operations in many linear, non-linear and
frequency-dependent circuits. The popularity of the op-amp as a
building block inanalog circuitsis due to its versatility. Due
tonegative feedback, the characteristics of an op-amp circuit,
itsgain, input andoutput impedance,bandwidthetc. are determined by
external components and have little dependence on temperature
coefficients or manufacturing variations in the op-amp itself.The
LM741 series are general purpose operational amplifiers which
feature improved performance over industry standards like the
LM709. They are direct, plug-in replacements for the 709C, LM201,
MC1439 and 748 in most applications. The amplifiers offer many
features which make their application nearly foolproof: overload
protection on the input and output, no latch-up when the common
mode range is exceeded, as well as freedom from oscillations. This
is the second stage of the amplifier section. This part further
amplifies the noise received by the ultrasonic receiver. This also
integrate the output of the amplifier.The amplifier's differential
inputs consist of a non-inverting input (+) with voltageV+and an
inverting input () with voltageV; ideally the op-amp amplifies only
the difference in voltage between the two, which is called
thedifferential input voltage. The output voltage of the
op-ampVoutis given by the equation:
Where Ais theopen-loopgain of the amplifier (the term
"open-loop" refers to the absence of a feedback loop from the
output to the input.
Figure:-Circuit diag. of Op amp
Figure:- op-amp amplifierOp amp Comparator
One input consists of the shifted, negative clipped amplified
output of the Opamp amplifier and the positive clipped amplified
output. The output of the comparator is by default high and when
the positive clipped portions exceed the negative clipped part due
to noise, the Opamp inverts. Inelectronics, acomparatoris a device
that compares twovoltagesorcurrentsand outputs a digital signal
indicating which is larger. It has two analog input terminalsandand
one binary digital output. The output is ideally
A comparator consists of a specialized high-gaindifferential
amplifier. They are commonly used in devices that measure and
digitize analog signals, such asanalog-to-digital
converters\(ADCs), as well asrelaxation oscillators. Anoperational
amplifier(op-amp) has a well balanced difference input and a very
highgain. This parallels the characteristics of comparators and can
be substituted in applications with low-performance requirements.In
theory, a standard op-amp operating in open-loop configuration
(without negative feedback) may be used as a low-performance
comparator. When the non-inverting input (V+) is at a higher
voltage than the inverting input (V-), the high gain of the op-amp
causes the output to saturate at the highest positive voltage it
can output. When the non-inverting input (V+) drops below the
inverting input (V-), the output saturates at the most negative
voltage it can output. The op-amp's output voltage is limited by
the supply voltage. An op-amp operating in a linear mode with
negative feedback, using a balanced, split-voltage power supply,
(powered by VS) has its transfer function typically written as:.
However, this equation may not be applicable to a comparator
circuit which is non-linear and operates open-loop (no negative
feedback).
Pi-filter
Thecapacitor-input filter, also calledpifilter due to its shape
that looks like theGreek letterpi, is a type ofelectronic
filter.The pi-filter converts the fluctuating ac noise into dc and
feeds into the Op amp comparator.Thecapacitor-input filter, also
called thepi filterdue to its shape that looks like theGreek
letter, is a type ofelectronic filter. Filter circuits are used to
remove unwanted or undesired frequencies from a signal.
Figure:- Pi Filter Circuit
A simple pi filter, containing a pair of capacitors, an
inductor, and a load.A typical capacitor input filter consists of a
filter or reservoircapacitorC1, connected across the rectifier
output, aninductorL, in series and another filter or smoothing
capacitor, C2, connected across the load, RL. A filter of this sort
is designed for use at a particular frequency, generally fixed by
the AC line frequency and rectifier configuration. When used in
this service, filter performance is often characterized by
itsregulationandripple. The capacitor-input filter operates in
three steps:1. ThecapacitorC1 offers lowreactanceto the AC
component of the rectifier output while it offers infinite
resistance to the DC component. As a result the capacitorshuntsan
appreciable amount of the AC component while the DC component
continues its journey to the inductor L.2. TheinductorL offers high
reactance to the AC component but it offers almost zero resistance
to the DC component. As a result the DC component flows through the
inductor while the AC component is blocked.3. ThecapacitorC2
bypasses the AC component which the inductor had failed to block.
As a result only the DC component appears across the load RL.The
component value for the inductor can be estimated as an inductance
that resonates the smoothing capacitor(s) at or below one tenth of
the minimum AC frequency in the power supplied to the filter (100
Hz from a full-wave rectifier in a region where the power supply is
50Hz). Thus if reservoir and smoothing capacitors of 2200
microfarads are used, a suitable minimum value for the inductor
would be that which resonates 2200 microfarads (F) to 10 Hz, i.e.
115 mH. A larger value is preferable provided the inductor can
carry the required supply current.
Figure:- Schmitt Trigger CircuitSchmitt trigger:-The next part
of the receiver circuit is the Schmitt trigger.The Schmitt trigger
is acomparator application which switches the output negative when
the input passes upward through a positive reference voltage. It
then usesnegative feedbackto prevent switching back to the other
state until the input passes through a lower threshold voltage,
thus stabilizing the switching against rapid triggering by noise as
it passes the trigger point. In this circuit the motion caused by
the object causes distortion at the receiver output. The comparator
output is by default high. When the noise levels detected are
substantially high, the comparator inverts itself and the trigger
is triggered. The output is fed to a Darlington pair. The Schmitt
trigger is acomparator application which switches the output
negative when the input passes upward through a positive reference
voltage. It then usespositive feedbackof a negative voltage to
prevent switching back to the other state until the input passes
through a lower threshold voltage, thus stabilizing the switching
against rapid triggering by noise as it passes the trigger point.
That is, it provides feedback which is not reversed in phase, but
in this case the signal that is being fed back is a negative signal
and keeps the output driven to the negative supply voltage until
the input drops below the lower design threshold. Schmitt trigger
devices are typically used insignal conditioningapplications to
remove noise from signals used in digital circuits, particularly
mechanicalswitch bounce. They are also used inclosed loopnegative
feedbackconfigurations to implementrelaxation oscillators, used
infunction generatorsand switching power supplies.
Fiqure:- schmitt trigger
Fiqure:- component list of ultrasonic sensor.Darlington pairThis
is a very high current gain section which when turned on by the
trigger from the Schmitt trigger, starts conducting and the buzzer
and led goes on.Transistors are an essential component in a sensor
circuit. Usually transistors are arranged as a pair, known as a
darlington pair.It is very important that you can identify this
arrangement of transistors and state clearly why they areused.A
darlington pair is used to amplify weak signals so that they can be
clearly detected by another circuit or a
computer/microprocessor.
The circuit below is a temperature sensor. When the temperature
drops below zero the LED lights. This type of system is often seen
in a car and warns the driver of the possibility of icy conditions.
The two transistors are known as a darlington pair. Without a
darlington pair the circuit would probably fail. The circuit
opposite is a Darlington Pair driver. The first transistors emitter
feeds into the second transistors base and as a result the input
signal is amplified by the time it reaches the output.The important
point to remember is that the Darlington Pair is made up of two
transistors and when they are arranged as shown in the circuit they
are used to amplify weak signals
Fiqure of Darlington pairWORKING OF THE CIRCUITAs 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.IC CIRCUIT:-
Anintegrated circuitormonolithic integrated circuit is a set
ofelectronic circuitson one small plate ("chip") ofsemiconductor
material, normallysilicon. This can be made much smaller than
adiscrete circuit made from independentelectronic components. ICs
can be made very compact, having up to several
billiontransistorsand other electronic componentsin an area the
size of a fingernail. The width of each conducting line in a
circuit can be made smaller and smaller as the technology advances;
in 2008 it dropped below 100nanometerand now is tens of
nanometers.
Figure of ic circuitPCB DESIGN
Figure of pcb design of ultrasonic circuit
APPLICATIONS :-
The motion detector circuit has a number of uses.
1. As burglar alarm: The circuit can be used as an alarm system
in homes, shops and even automobiles. The device is small,
sensitive and has a low cost. This can be used in homes and shops
to guard safes and other valuables\
2. .As a people counter device:Apeople counteris a device used
to measure the number and direction of people traversing a certain
passage or entrance per unit time. The resolution of the
measurement is entirely dependent on the sophistication of the
technology employed. The device is often used at the entrance of a
building so that the total number of visitors can be recorded.The
motion detector can be used in daytime to count the number of
people entering a shop by attaching a counter circuit and can be
converted into a burglar alarm at night by minimum
modifications.
3. As High Security Safe Alarm:When integrated with a high
security safe it can trigger an alarm even in the event of a minute
movement. Hence it can serve the purpose of handling attempted
robberies on high security vaults.
4. Motion Sensing Camera Trigger:As the name suggests the device
can be used to trigger cameras to automatically operate the
presence of motion in surroundings. This can be used in wildlife
photography and security cameras.