Transcript WORKS

WELCOME
To ELECTRONICS AND COMMUNICATION
DEPARTMENT
WORKSHOP TRAINING
JULY 2011
DEPARTMENT OF ELECTRONICS AND
COMMUNICATION ENGINEERING
Topics to be Covered
 Section-I
Introduction
Electronics Components
Semiconductor Physics
Electronic devices
Basic of Digital Electronics
Electronics Instrumentation
 Section-II
Project Work
Introduction
 Electronics:---
It is the word derived from electron which is present in all
materials.
The Branch of science and engineering which deals with the
flow of electrons through vacuum or gas or semiconductor is
known as electronics.
Applications of Electronics
 Electronics is available in every sphere of life.
 Electronics deals in the micro and milli range of voltage, current
and power, and controls kilo, mega volts, amperes and watts.
1. Communications And entertainments
2.Industrial Applications
3. Defence Applications
4. Applications in Medical sciences
5.Applications in Auto mobiles
6.Digital Electronics
7.Instrumentation
Communications And entertainments
Heinrich Hertz
Industrial Applications
Defence Applications
Applications in Medical sciences
Applications in Auto mobiles
Digital Electronics
Instrumentation
QUIZ
 MSI means………………?
 Birth of electronics took place in 1897 with the invention of
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……………..?
The system of units adopted in INDIA is…………….?
The term giga stands for…………….?
The term eV stands for…………..?
The charge on an electron is………….coulomb?
The term micro stands for……………..?
The term pico stands for…………..?
The velocity of light is…………..m/s?
Any Questions??
Electronics Components
TYPES OF COMPONENTS
 ACTIVE COMPONENTS
The electronic components which are capable of amplifying
or processing an electrical signal are called active component.
Such as..
vacuum diodes, vacuum triodes, vacuum pentode, gas
diodes, zener diodes, transistor, field effect transistor,
unijunction transistors, silicon control rectifier, tunnel diode
etc.
 PASSIVE COMPONENTS
Components which are not capable of amplifying or
processing an electrical signal are called passive components
such as resistor, capacitor and inductor.
Passive components
 RESISTORS
Symbol Of Resistor (R)
 It is used to limit the amount of current or divide the voltage
in an electronic circuit.
MATHEMATICAL
- R = ( * L) / A
REPRESENTATION
RESISTANCE
 The ability of resistor to oppose the flow of current is called
Resistance.
 Unit of resistance R is ohm.
ohm
Types of Resistors
 There are two main Characteristics of resistance
Resistance in ohms
2. Power rating in watts
FIXED RESISTORS
1. Carbon-composition Resistors:
Made of mixture of carbon or graphite
And clay. Two materials are mixed in the proportion for the
desired value of R.
1.
Carbon composition
A
broken resistor showing the ceramic core.
A carbon resistor with and without
the outer paint.
 Carbon composition are readily available in values ranging
from 1 ohm to 22 Mega ohm, having a tolerance range of
5 to 20 %.
 FILM TYPE RESISTOR
Wire wound resistor
 Nichrome, tungsten is used for wires.
 Hollow porcelain cylinder
 Ends are joined with metal
pieces.
 Assembly is coated with
enamel containing powdered
Glass.
Resistor colour coding
B
B
R
O
Y
G
B
V
G
W
Question
 A resistor has a colour band sequence; red, black, red, gold
o
o
o
o
o
o
first digit----2
second digit—0
third multiplier----100 ohm
gold--------------5%
result----2000ohm or 2 k ohm with 5%
tolerance
Question????
Variable Resistors
 Some times it is require to change the value of resistance
while in circuit such as voice controller, or speed controller,
brightness controller etc.
 This can be done with the held of variable resistor. These
resistors can be carbon composition or wire wound.
 Carbon composition Resistor
 Wire wound variable Resistor
Carbon composition resistor
 A thin carbon coating on pressed paper or a molded carbon
disc constitutes the carbon
composition resistance element.
 Available from 1000 ohm to
5Mohm.
 Power rating from1/2 to 2W.
Wire Wound variable Resistors
 Wire is wound over a dough shaped core of Bakelite or
ceramic.
 The two ends of the resistance wire are joined to the external
soldering plug terminals. 1 and 3.
 The middle terminal is connected to the variable arm that
contacts the resistor element.
Quiz
 The electronic component which cannot process the signal
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are called ……………components.
The electronic component which can process the signal are
called………………components.
The resistors are rated in………and………..
When there are only three color bands on the resistor, the
tolerance is…………
The third band on the resistor shows the…………….
180ohm and 10% tolerance, the colour bands in the sequence
will be…………………
ELECTRONICS INSTRUMENTS
CONTENTS
 INTRODUCTION TO CRO
 FUNCTION GENERATOR
 DSO
 MULTIMETER (DIGITAL AND ANALOG)
CRO
 Cathode ray oscilloscope
 It is used for the development of electronic circuits.
 It shows the amplitude of electrical signals(power, current or
voltage)as a function of time.
 CRO is faster than other devices.
BLOCK DIAGRAM OF CRO
BLOCK DIAGRAM
(i) Cathode ray tube
(ii) vertical deflection system
(iii) delay line
(iv) horizontal deflection system
(v) Trigger circuit
(vi) Time base
(vii) Power Supply
CRT
 Electron gun produces an electron beam.
 This beam is allowed to pass down the tube and to fall on the
screen.
 The screen is formed by the flat end of glass tube which is
coated with the fluorescent material.
 The point at which the electron beam strikes the screen, a
spot is formed.
 Beam passes through two plates i.e, vertical deflection plates
and horizontal deflection plates.
 Electron Gun Assembly
 Consist of heater, focusing anodes and cathode.
FLOURESCENT SCREEN
 The front end of CRT acts as a Fluorescent Screen. Inner side
is coated with phosphor.
 A phosphor converts the electrical energy to light energy.
Phosphor crystals get excited and they emit light. This
phenomenon is called fluorescence.
HORIZONTAL DEFLECTION SYSTEM
 Time base generator
 Trigger circuit
 Horizontal amplifier
Time base generator
 It generate saw tooth voltage, which will deflect the beam in
the horizontal direction.
 The CRT spot is deflected at a constant time dependant rate
because of the voltage.
TRIGGER CIRCUIT:
 This circuit ensures that the horizontal sweep begins at the
same point of the vertical input signal.
 Without this there is no synchronization between sweep
signal and the signal which is to be observed on the vertical
deflection plates.
DELAY LINE
 Every electronic circuit which are used in oscilloscope take
certain time for the required operation. such as attenuators,
amplifiers, waveshapers etc.
 So Delay line is used to delay the signal for some time in the
vertical sections. Generally, a time delay of 200 ns is provided
to observe the leading edge of the waveforms.
 the time delay at the horizontal deflecting plates the time
delay is about 80ns.
 Thus horizontal sweep starts prior to the vertical sweep.
FRONT PANEL CONTROL OF CRO
 Basic general purpose controls
 Controls in the Vertical Section
 Controls in the Horizontal Section
 Special Controls
Display

A is the display. This can be a phosphor screen or an LCD, and is usually about 100mm corner to
corner.
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B shows the trace. This is the line drawn by the scope to represent the signal. On a CRO, this line
is created by a bright dot moving across the screen at high speed (sometimes faster than the speed of
light - because nothing is physically moving across the screen, this does not break any rules). On a
digital scope, the line is drawn on the LCD like a graphical calculator.
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The screen is overlaid with a grid of horizontal (C) and vertical (D) lines, called the graticule,
which divides the screen into squares, called major divisions. The graticule is usually 10 major
divisions wide and 8 tall.
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The central horizontal and vertical lines (E) are usually thicker than the others and are divided
into minor divisions, usually five per major division. When we talk about "divisions" in later
sections, we will always mean the major divisions - the minor divisions are just to aid measuring.
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There are also special horizontal lines labeled "0" (2.5 divisions below the centre) and "100" (2.5
divisions above it). The "10" and "90" lines have tick marks like the central axes. These four
horizontal lines are guides for scaling the signal for rise-time measurement.
Power, Calibration and Display Controls
 1 is the Power On/Off Button. 2 is the Power Indicator which lights when the
oscilloscope is on. This may be an LED in newer scopes or a neon tube in older scopes.
 3 is the trace rotation (TR) control. This sets the inclination of a flat signal relative to
the graticule. This is usually a Trimpot and needs to be set using a flat-bladed screwdriver.
Once set, this control should retain its position and will rarely need adjusting.
 4 is the intensity of the trace. Turning this up increases the brightness of the trace, and
turning it down makes it dimmer. An overly bright trace can damage the phosphor of the
screen if the dot is moving too slowly.
 The trace can get fuzzy if the electron beam is not focused correctly. The focus control
(5) sets this. Most scopes can focus the beam to form a trace about 1mm wide.
 6 is the calibration point. This gives a steady square wave at a set frequency and voltage,
allowing the scaling of the trace to be set accurately. Sometimes, more than one
frequency and voltage is available to give a more representative calibration. The standard
calibration signal is between 0V and 2V at 1KHz.
Vertical Axis Controls
 When plotting a signal against time (the standard use for a scope), the vertical axis
represents voltage. Most controls for the vertical axis are duplicated for each channel to
give independent control over each signal.
 7 controls the position of the trace. It can be adjusted to set the voltage relative to a
ground, or it can be adjusted to separate the two signals - perhaps the first channel in the
top half of the screen and the second channel in the bottom.
 8 inverts the relevant channel. That is, the negative voltage is displayed, and the trace is
upside-down.
 9 is the vertical scale control, often called the volts/div. control. This sets the height of
the trace. It operates in discrete steps.
 10 is a variable height control. It can adjust the height of the trace up to the next set
increment on the volts/div. control. When set to CAL, the height is as stated on the
volts/div. control.
 11 is the AC/DC toggle. When set to AC, any DC component of the voltage is filtered
out by switching a capacitor in series with the input signal, leaving just an AC voltage.
This is useful when the DC component swamps the AC component, making it either too
small to see or driving it off the top of the screen. When set to DC, the signal is displayed
as is.
 12 is the GND toggle. By selecting this, the input signal is ignored, and the
trace shows 0V. This can be useful to measure a voltage or to eliminate one of
the traces from the display.
 13 is the Channel 1 signal input and 14 is the Channel 2 input. This is where the
oscilloscope's probe is plugged in.
 Each channel has a copy of most of these controls (except chop/alt, which
applies to all channels). The way the channels are combined is set using 15,
which is usually a sliding switch. When set to CH. 1, only the trace from
Channel 1 is displayed, and likewise for CH. 2. When DUAL is selected, the
traces are shown side by side. This is when the chop/alt control
applies. ADD shows the sum of the two traces as one trace. By inverting the
traces, one can be subtracted from the other. This can be seen in the illustration
below. This shows a square wave on one channel and a sinusoidal wave on the
other. On the left, the scope is set to "dual", and the two traces are shown side
by side. On the right, the scope is set to "add", and the trace is the sum of the
two signals.
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Horizontal Axis Controls
 When operating in the normal voltage vs. time mode, this axis represents time. The
primary control is the time base selector, 19. The time base is the length of time
displayed per major horizontal division on the screen. This ranges from about 0.1
milliseconds to about 1 second (or more on digital scopes).
 The position of the trace from side to side is controlled by 17. This is useful if part of the
trace is off the edge of the screen but you don't want to change the time base.
 The ×10 MAG control, 16, is a very useful control if you want to quickly zoom in on a
feature without changing the timebase and losing your settings. This buttom magnifies
the central area of the trace by a factor of 10 in the horizontal direction (but leaves the
voltage height unchanged).
 18 toogles the mode between the usual voltage vs. time format and the XY mode. This
continuously plots the voltage on Channel 1 along the horizontal axis against the voltage
on Channel 2 (the vertical axis). This can be extremely useful to analyse frequency or
phase relationships. This is a complex topic, and will be covered in its own section later
in the module.
 20 and 21 act in much the same way as 10 does on the vertical axis. This diagram shows
it to be slighly different from the vertical control. To select a non-standard timebase,
press 20, and adjust 20 until the correct setting is obtained. To return to a calibrated time
base, press 20 again. Sometimes these controls are the same style as 10, sometimes the
vertical controls are like these.
 22 is the GND terminal of the scope. This is used to set a "datum"
voltage against which to measure the voltages on the input
channels. Be careful when using isolated mains voltage circuits, as
the "ground" is sometines floating at mains voltage, and can short
to the real ground, casuing injury or death.
 23 toggles between chop-mode and alt-mode. Chop-mode
means that when the scope is drawing two signals side by side it
alternates rapidly between the two over the course of passing
across the screen. This action is called chopping. Alt-mode
alternates at the end of each pass, and can appear to flicker at slow
speeds.
FUNCTION GENERATOR
 Function generator is an instrument which produces
different functions (waveforms)at the output.
 A function generator can be capable of generating Sine,
square and triangular functions simultaneously at the output.
 Range of frequencies is from few Hz to several MHz.
 Amplitude range is from mv to few tens of volts rms.
Block Diagram of Function
generator
Working
 Frequency control can be internal or external.
 If external then DC voltage is applied.
 Upper and lower current sources supply constant DC
currents I1 and I2 opposite in directions.
 Let upper supply is ON and supplying dc constant current I1
to an integrator. Now the output of an integrator is
Voi=1/c∫I1 dt
 Voi is the linear ramp wave increasing towards positive as
shown in fig.
 Ramp voltage is less than upper triggering point(UTP).
Features of Function Generator
 Freq range- 0.01Hz to 100 KHz
 It can produce different waveforms like sine, square,
triangular, sawtooth etc.
 Accuracy is within (+-1%)
 Distortion is less than 1% for sine wave.
DSO (Digital storage oscilloscope)