Chapter-7
Application of Electronic
System
INSTUMENTATION SYSTEM
• Instrumentation system is a collection of instruments, devices,
hardware or functions or their applications for the purpose of
measuring, monitoring, or controlling an industrial process or
machine or any combination of these.
Classification of instrumentation system
Analog system
Digital system
Difference between Analog and Digital
Analog
Digital
Description
Linear transmission of signal.
Signal is converted into binary code (0s and
1s) before transmission.
Used for
Sound, light, temperature, position, or
pressure.
Computing and electronics
Representation
Uses continuous range of values to
represent information.
Uses discrete or discontinuous values to
represent information.
Advantages
Potential for an infinite amount of signal
resolution, higher density, simpler
technology, cheaper.
Easier manipulation, error detection and
error correction, improved quality of sound,
create effects, does not wear out over time.
Disadvantages
Might include unwanted sound or noise,
signal loss, distortion due to noise, limitation
on transmitted data size, wears out over
time.
Expensive, prone to loss of quality in
translation of data.
Wave denotation
Sine waves
Square waves
Measured
medium
Quantity to be
measured
Primary sensing element
Variable conversion element
Single conditioning element
Data presentation
element
Data transmission element
Data storage
Variable manipulation element
Presented data
observer
Fig : Functional elements of an instrumentation system
Components of Generalized
Instrumentation System:
A generalized instrumentation system consists of the following
components :1.Primary Sensing Element
2.Variable Conversion Element
3.Variable Manipulation Element
4.Data Transmission System
5.Data Processing Element
6.Data Presentation Element
Primary sensing element
The primary sensing element is that which first receives energy from measured
medium and produces an output depending in some way on the measured
quantity.
Variable Conversion Elements
The output signal of the primary sensing element is some physical variable, such as
displacement or voltage. For the instrument to perform the desired function, it may
be necessary to convert this variable to another more suitable variable while
preserving the information content of the original signal . An element that
performs such a function is called a variable conversion element.
It should be noted that not every instrument includes a variable conversion
element, but some require several.
Variable Manipulation Element:
Variable manipulation element manipulates and amplifies the
output of the variable conversion element. It also removes noise (if
present) in the signal.
Data Processing Element:
Data processing element is an important element used in many
measurement systems. It processes the data signal received from the
variable manipulation element and produces suitable output.
Data processing element may also be used to compare the measured
value with a standard value to produce required output.
Data Transmission System:
Data Transmission System:
Data Transmission System is simply used for transmitting data from one element to another. It acts
as a communication link between different elements of the measurement system. Some of the data
transmission elements used are cables, wireless antennae, transducers, telemetry systems etc.
Data Presentation Element:
It is used to present the measured physical quantity in a human readable form to the observer.
It receives processed signal from data processing element and presents the data in a human
readable form. LED displays are most commonly used as data presentation elements in many
measurement systems.
What is a Transducer?
 A transducer is a device which transforms a non-electrical
physical quantity (i.e. temperature, sound or light) into an
electrical signal (i.e. voltage, current, capacity…)
A transducer will have basically two main components. They are :
1. Sensing Element : The physical quantity or its rate of change
is sensed and responded to by this part of the transistor.
2. Transduction Element : The output of the sensing element is
passed on to the transduction element. This element is
responsible for converting the non-electrical signal into its
proportional electrical signal.
Examples:
• Antenna: is the most basic transducer and can be made from a simple
piece of wire. It converts electromagnetic energy into electricity when
it receives signals and does the opposite when it transmits.
• Strain gauges: have a long thin wire attached to a foil backing which is
glued to an object. When the object changes shape, the strain gauge
also changes shape and its resistance changes. The amount of stress
or strain in the object is calculated from this change in resistance.
• Microphone and Speaker: Microphones convert sound pressure
waves into electrical current, while speaker convert electrical current
into sound pressure waves.
Structure :
A Transducer is made of three blocks :
1. Input I/F
2. Sensor
3. Output O/F
Classifications
1.
2.
3.
4.
5.
On the basis of Transduction form used.
As primary and secondary transducers.
As active and passive transducers.
As analog and digital transducers.
As transducers and inverse transducers.
Types of Energy Transfers :
Sensors
• A sensor is a special type of transducer that is used to generate
an input signal to a measurement, instrumentation or control
system.
• Signal produced by a sensor is an electrical analogy of a
physical quantity such as distance , velocity , acceleration etc.
Common Sensors
Type of Sensors
1. Analog or Digital
2. Active or Passive- Require external power supply to operate/no need.
• Analog Sensor Analogue Sensors produce a continuous output signal or voltage which is
generally proportional to the quantity being measured.
 Physical quantities such as Temperature, Speed, Pressure, Displacement, Strain
etc are all analogue quantities as they tend to be continuous in nature.
Thermocouple used to produce an Analogue
Signal
Digital Sensors
• Digital Sensors produce a discrete digital output signals or voltages
that are a digital representation of the quantity being measured.
• Digital sensors produce a Binary output signal in the form of a logic
“1” or a logic “0”, (“ON” or “OFF”).
• Digital signal only produces discrete (non-continuous) values which
may be outputted as a single “bit”, (serial transmission) or by
combining the bits to produce a single “byte” output (parallel
transmission).
Light Sensor used to produce an Digital Signal
Strain
When a bar is pulled, it elongates by L, and thus it lengthens to L (original length) + L (change in
length). The ratio of this elongation (or contraction), L, to the original length, L, is called strain,
which is expressed in  (epsilon):
L (change in length)
d0 –d
L (original length)
d0
1 =
L
- 24
-
L
DEFINITION
• A strain gauge is an example of passive transducer that converts a mechanical displacement into a change
of resistance.
• A strain gauge is a thin, wafer-like device that can be attached to a variety of materials to measure applied
strain.
HISTORY
A brief history of the Strain Gauge:
• 1856 : Lord Kelvin first reported on a relationship between strain and the resistance of wire conductors.
• Early 1930s : Charles Kearns made the first notable use of bonded resistance strain gauges to measure
vibratory strains in high performance propeller blades.
• 1937/8 : Arthur Ruge discovered that small diameter wires made of electrical resistance alloys could be
bonded to a structure to measure surface strain.
• 1952 : At this time, printed circuits were emerging, and Saunders-Roe developed the idea of making a strain
gauge by etching the pattern for the gauge from a thin foil.
STRUCTURE
• The majority of strain gauges are foil types, available in a wide choice of shapes and sizes to suit a variety
of applications.
• They consist of a pattern of resistive foil which is mounted on a backing material.
• They operate on the principle that as the foil is subjected to stress, the resistance of the foil changes in a
defined way.
WORKING
• The strain gauge is connected into a Wheatstone Bridge circuit. The change in resistance is proportional
to applied strain and is measured with Wheatstone bridge.
WORKING
• The sensitivity of a strain gauge is described in terms of a characteristic called the gauge factor, defined as unit
change in resistance per unit change in length, or
• Gauge factor is related to Poisson's ratio µ by,
K=1+2µ
TYPES
Based on principle of working :
• Mechanical
• Electrical
• Piezoelectric
Based on mounting :
• Bonded strain gauge
• Unbonded strain gauge
Based on construction :
• Foil strain gauge
• Semiconductor strain gauge
• Photoelectric Strain gauge
MECHANICAL STRAIN GAUGE
• It is made up of two separate plastic layers. The bottom layer has a ruled scale on it and the top layer has a
red arrow or pointer.
• One layer is glued to one side of the crack and one layer to the other.
• As the crack opens, the layers slide very slowly past one another and the pointer moves over the scale. The
red crosshairs move on the scale as the crack widens.
ELECTRICAL STRAIN GAUGE
When an electrical wire is
stretched within the limits of
its elasticity such that it does
not break or permanently
deform, it will become
narrower and longer, changes
that increases its electrical
resistance end-to-end.
PIEZOELECTRIC STRAIN GAUGE
• Piezoelectric generate electric voltage when strain is applied over it.
• Strain can be calculated from voltage. Piezoelectric strain gauges are the most sensitive and reliable
devices.
BONDED STRAIN GAUGE
• A bonded strain-gauge element, consisting of a metallic wire, etched foil,
vacuum-deposited film, or semiconductor bar, is cemented to the strained
surface.
UNBONDED STRAIN GAUGE
• The unbonded strain gauge consists of a wire stretched between two points in an insulating medium such
as air. One end of the wire is fixed and the other end is attached to a movable element.
FOIL STRAIN GAUGE
• The foil strain gauge has metal foil photo-etched in a grid pattern on the
electric insulator of the thin resin and gauge leads attached,
SEMICONDUCTOR STRAIN GAUGE
• For measurements of small strain, semiconductor strain gauges, so called piezoresistors,
are often preferred over foil gauges. Semiconductor strain gauges depend on the
piezoresistive effects of silicon or germanium and measure the change in resistance with
stress as opposed to strain.
PHOTOELECTRIC STRAIN GAUGE
• The photoelectric gauge uses a light beam, two fine gratings, and a photocell
detector to generate an electrical current that is proportional to strain. The
gauge length of these devices can be as short as 1/16 inch, but they are costly
and delicate.
STRAIN GAUGE
STRAIN GAUGE SELECTION CRITERIA:
• Gauge Length
• Number of Gauges in Gauge Pattern
• Arrangement of Gauges in Gauge Pattern
• Grid Resistance
• temperature sensitivity
• Carrier Material
• Gauge Width
• Availability
• low cost
ADVANTAGES & DISADVANTAGES
Advantages
• There is no moving part.
• It is small and inexpensive.
Disadvantages
• It is non-linear.
• It needs to be calibrated.
Digital multimeter (DMM)
DMM
(Digital Multimeter)
•
A digital multimeter (DMM) is a test tool used to measure
two or more electrical values—principally voltage (volts), current
(amps) and resistance (ohms).
• Digital multimeters combine the testing capabilities of single-task
meters—the voltmeter (for measuring volts), ammeter (amps) and
ohmmeter (ohms).
• In the early 1920s, the first multimeter named (Avometer) is
attributed to British Post Office engineer, Donald Macadie, who
became dissatisfied with the need to carry many separate
instruments required for maintenance
of telecommunications circuits.
Mechanism of Multimeter
Symbols used in dmm
Types of multimeter
Analog Multimeter
&
Digital Multimeter
Oscilloscope
• Oscilloscope is an very important
test instrument in electrical and
electronics field.
• It is used to look at the ‘shape’ of
electrical signal by displaying a graph
of voltage against time on screen.
• It is like a voltmeter with the
valuable extra function of showing
how the voltage varies with time.
• Oscilloscope are commonly used to
observe the exact wave shape of an
electrical signal.
Types of oscilloscope

Digital oscilloscopes
1.digital storage oscilloscope
2.Digital sampling oscilloscope
3.Handheld oscilloscope
4.PC-based oscilloscope
5.Mixed signal oscilloscope
Cathode ray oscilloscope
1.Dual-beam oscilloscope
 Analog storage oscilloscope
 Analog sampling oscilloscope
Cathode ray oscilloscope
• Developed by German physicist Ferdinand Braun.
• Mostly used test instrument.
• It contains cathode ray tube.
• CRT is used to generate beam of electrons.
• Electrons produce visible patterns, or graphs, on a phosphorescent
screen.
Block diagram of CRO
Working principle
• Oscilloscope operational
figure is shown aside.
• It basically works on the
amplifier and triggering
networks.
CONSTRUCTION
FRONT PANELS
• FOCUS CONTROL: This control adjusts CRT focus to obtain the
sharpness, most-detailed trace.
• INTENSITY CONTROL: This adjusts trace brightness.
• BEAM FINDER: It limits the beam deflection.
• GRATICULE: The graticule is a grid of squares that serve as reference marks
for measuring the displayed trace.
• TIME BASE CONTROLS: These selects the horizontal speed of the CRT’s spot
as it crates the trace; this process is commonly referred to as the sweep. In
all but the least-costly modern scopes, the sweep speed is selectable and
calibrated in units of time per major graticule division.
APPLICATIONS OF OSCILLOSCOPE
•
•
•
•
•
•
•
•
•
•
Dc voltage measurement
Measurement of voltage between two points on the waveform
Elimination of undesired signal components
Time measurement
Time difference measurement
Pulse rise time and fall time measurement
Frequency measurement
Relative measurement
Sweep multiplication
Application of X-Y operation
History of Remote Control
• The first remote intended to control a television was developed by Zenith Radio
Corporation in 1950.
• The remote, called "Lazy Bones", was connected to the television by a wire
• A wireless remote control, the "Flashmatic", was developed in 1955 by Eugene
Polley.
• It worked by shining a beam of light onto a photoelectric cell.
• By the early 2000s, various remote control devices were developed to operated
electronic equipments like Home Theatre, VCR, Audio Amplifier etc.
• In the early 2010s, many smartphone manufacturers began incorporating
infrared emitters into their devices, thereby enabling their use as universal
remotes via an included or downloadable app.
Techniques used in Remote Control
• The main technology used in home remote controls is Infrared (IR) light
• Most remote controls for electronic appliances use a near infrared diode to emit a beam of light that
reaches the device.
• Today, IR remote controls almost always use a pulse width modulated code, encoded and decoded
by digital computer.
• Infrared (IR) remote controls use light, requiring line of sight to operate the destination device.
• As a complementary to IR, the radio remote control is used with electric garage door or gate
openers, automatic barrier systems, burglar alarms and industrial automation systems.
Block Diagram of Remote Control
Infrared transmitter
diode
Microprocessors
Keyboard Functions
Infrared diode
driver
Infrared diode
receiver
Signal
amplifier
Microcontroller
Electronic Device
Usage of Remote Control System
• It is used for controlling substations, pump storage power stations and HVDC-plants.
• It is used by military troops to detonate bombs.
• These days, it is widely used in gaming consoles.
• Any application that supports shortcut keys can be controlled via IR remote controls from other
home devices (TV, VCR, AC).
• Also used in space travels making the control system much convenient. For instance, The Soviet
Lunokhed vehicles were remote controlled from the grounds.
• Remote controls are used in photography, in particular to take long-exposure shots
Limitations of Remote Control
• It requires an operator to “aim” the hand held unit in the direction of the receptor.
• Limited reliable range.
• It is attenuated by dust, smoke, rain and fog that will substantially reduce operating range.
• Operators cannot control the equipment if vehicles and other obstructions are between the
transmitter and receiver.
DATA LOGGER
A data logger is an electronic device that record data over time or in relation
to location of instrument at different parts of the plant effortlessly as quickly
as often and as accurately as desired. Increasingly, but not entirely, they are
based on a digital processor(or computer). They generally are small, battery
powered, portable, and equipped with a microprocessor, internal memory
for data storage and sensors.
input signals
Input
scanner
Signal amplifier
conditioner
Analog to digital
converter
Recorder
convert
record
programmer
start
Real time clock
• Input signals: It may be high level signals from pressure transducers, low
level signals from thermocouple, AC, ON, OFF signals from switch and
relays, etc.
• Input scanner: It is an automatic sense switch which selects signals in turn.
• Signal amplifier: It amplifies low level signal up to 5V output
• signal conditioner: It changes signal to more linear and suitable form of
digital analysis.
• Analog to digital converter: It converts the analog signals into digital
signals suitable for driving the recording equipment.
• Recorder: A recorder records electrical and non-electrical quantities as
a function of time. The record may be written or printed.
• Programmer: The programmer is used to control the sequence of
operation of various items of data logger.
• Real time clock: It commands the programmer to sequence one set of
measurement at the intervals selected by the user.
Application Areas
1. Weather station recording(wind, speed, temperature, humidity,
etc.)
2. Hydrographic recording(water level, depth, flow,etc.)
3. Wildlife research
4. Vehicle testing
5. Environmental monitoring
Introduction:
• A display character is an electronic alpha-numerical display.
• It is mainly capable of showing text.
• This includes electromechanical split-flap display, vane displays,
and flip-disc display.
• It also includes all-electronic liquid-crystal display, LED display,
etc.
•There are several ways to form text for display:
-A segment display uses lines.
- A dot-matrix display uses a grid of dots.
-In LCD, LED, VFD both (vane &disc) can be seen.
• For split-flap displays, the characters are pre-printed.
•For nixie tubes, the display elements are controlled by electronics(to
correct physical sequence to show the desired information).
Dot matrix display:
• A dot-matrix display is a display device used to display information
machines, clocks, etc.
on
• It is used in devices requiring a simple display device of limited resolution.
•The display consists of a dot matrix of lights arranged in a rectangular
configuration.
• By switching on or off selected lights, text or graphics can be displayed.
• It converts instructions from a processor into signals which turns on or off lights.
Dot matrix display
Pixel resolutions:
• "A Matrix Display in the size 20×2" – This is a classic 5×7 dot matrix.
• LCD used in some early cellphones and vending machine. Common
sizes of dot matrix displays:
128×16 (Two lined)
128×32 (Four lined)
128×64 (Eight lined)
 Other sizes include:
• 92×31 (Four or three lined)
Character resolutions:
• A common size for a character is 5×7 pixels, either separated with blank lines with no
dots.
• This is seen on most graphics calculator.
• A smaller size is 3×5 (or 4×6 when separated with blank pixels). This is seen on the TI80 calculator as a "pure".
• The disadvantage of the 7×5 matrix and smaller is that lower case characters
with descended are not practical.
• Dot matrix displays of sufficient resolution can be programmed to emulate the sevensegment numeral patterns.
• A larger size is 5×9 pixels, which is used on many Natural Display calculators.
Character resolution
Seven-segment display:
• A seven-segment display (SSD), is a form of electronic display
device for displaying decimal numbers.
• It is used in digital clocks, electronic meters, and other electronic
devices that display numerical information.
Seven-segment display
How to Display Numbers on 7 Segment
Display?
If we want to display the number “0”, then we need to glow all the LEDs except
LED which belongs to line “g” (see 7 segment pin diagram above, so we need a
bit pattern 11000000. Similarly to display “1”we need to glow LEDs associated
with b and c, so the bit pattern for this would be 11111001. A table has been given
below for all the numbers while using Common Anode type 7 segment display
unit.
Digit to Display
hgfedcba
Hex code
0
11000000
C0
1
11111001
F9
2
10100100
A4
3
10110000
B0
4
10011001
99
5
10010010
92
6
10000010
82
7
11111000
F8
8
10000000
80
9
10010000
90
Fourteen-segment display:
• A fourteen-segment display (FSD) is a type of display based on 14 segments.
• It can be turned on or off to produce letters and numerals.
• It is an expansion of the more common seven-segment display.
• Electronic alphanumeric displays may use LEDs, LCDs, etc.
• A character generator is used to translate 7-bit ASCII character codes to the 14
bits.
Fourteen-segment display
Applications:
• Fourteen-segment gas-plasma displays were used in pinball
machines.
• It is used to produce alphanumeric characters on calculators.
• It is used in displays fitted to telephone Caller ID units, gymnasium
equipment, VCRs, etc.
• Such display is common on pinball machines for displaying the score.
Clock Counter Measurement
• Clock counter measurement is common for many physical
parameters.
There are many clock counter measurements-ramp
counter, integration op-amp counter , count up measurements ,
successive counting measurement
Input Signal
Co
Comparator
8 bit D/A
converter
8 bit Converter
Decoder
Stop Pulse
Display Unit
Clock pulse
Explanation
The DC voltage to be measured from the sensor is fed to comparator. The
negative high output, initially from the comparator is passed to counter and
with input of clock pulse, and the MSB of counter is set high and all other
bits low. These bits are the input to D/A converter whose output is
corresponding analog voltage of binary pattern in counter and is fed to the
non inverting terminal of the comparator. If the output of the comparator is
still negative, then the bit one significant less than MSB is set retaining
MSB high. If the output is greater than zero, MSB is reset and the one
significant less than MSB is set. In this way , the process continues until the
output from the comparator is zero or nearly zero. The binary value in
counter when the output of comparator is zero is the final digital value of
the input analog voltage from the counter
Regulated Power supply
• Power supply convert alternating current to the direct (DC) current mainly convert 110240v AC
• Three types of power supply:
–
–
–
–
Linear power supply
Switched mode (SMPS)
Uninterrupted (UPS)
power SMPS stands for Switch Mode Power Supply.
• This receives 230V AC and translates it into different DC levels such as +5V, -5V, +12V, 12V.
Linear power supply
• Linear power supply: transformer is used to convert voltage.
• Transformer convert the line AC voltage to a smaller peak voltage
• Rectifies AC signal produces large waveforms , capacitor filter is used
filter the rectified wave which contain small pulses (ripple).
• Depend on requirements regulator adjust the output voltage
• Good line and load regulation lower output voltage ripples.
Operation
• The power supplies used in computers are switched mode power
supplies.
• The primary power received from AC mains is rectified and filtered
as high-voltage DC.
AUDIO VIDEO SYSTEM
A system in which information exchange takes place in audio visual environment
i.e. Message/information consist of audio-video signals is called audio video
system . For example , television, telemedicine services, teleconferencing services ,
etc.
High Definition
Component Video
Time
Compression
FM
MOdulator
Sound
ADC +
Compression
Satellite
Broadcast
Time MUX
Sync Signal
ADC +
Compression
AM-VSB
Modulator
Block Diagram of typical audio video transmission
Cable
Broadcast
High definition video from HD camera is taken and time compression is
applied.
Sound and sync signal are digitized using ADC and compressed to reduce bit
rate.
Time compressed HD – video, digitally compressed sound and sync signals
are time multiplexed according to standards.
The standards signal are then modulated and transmitted FM modulation is
done if satellite broadcasting is there and AM–VSB modulation is done if
cable broadcasting is to be done.
Signal from Satellite
Audio Processing
Speaker
FM
Demodulator
Decoder(DeMUX +
De-compressor)
From
Cable
Video processing
AM-VSB
Demodulator
Sync Processing
Block Diagram of Typical audio video reception
High Definition
display
Incoming signal is selected and signal demodulation takes place.
Demodulation signal output gives compressed video bit stream, compressed
sync bit stream and uncompressed audio bit stream.
Thus, video bit stream is processed by audio processing stage where
decompression and D to A conversion takes place.
Audio stream is processed by audio processing stage where DAC is used to
convert digitized audio into analog audio signal and then it is pre-amplified and
power amplified.
Finally, video is displayed on high definition display and sound through speaker.
Comparison Between Analog and Digital
Instrumentation
1) Accuracy:-Digital is more than analog instruments.
2)Resolution:-In analog meters, it is in the range of 1/100 and in digital meters
of 1/1000 on less. So digital are better in terms of resolution.
3)Power Requirement:-Digital meters
meters.
draw negligible compared to analog
4)Cost and portability:-Due to uses of Modern
are extremely portable and low at cost.
IC technology digital meters
5) Range and polarity:Digital instruments incorporate automatic polarity and range
indications , but in analog we need to set them.
6)Observational errors:Digital meters are free from errors as they directly indicate the
quantity being measured in decimal.