To ELECTRONICS AND COMMUNICATION DEPARTMENT WELCOME.

To ELECTRONICS AND COMMUNICATION DEPARTMENT

WELCOME

JULY 2011DEPARTMENT OF ELECTRONICS AND

COMMUNICATION ENGINEERING

WORKSHOP TRAINING

Topics to be CoveredSection-I Introduction

Electronics Components Semiconductor Physics Electronic devices Basic of Digital Electronics Electronics InstrumentationSection-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 ElectronicsElectronics 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 entertainments2.Industrial Applications3. Defence Applications4. Applications in Medical sciences5.Applications in Auto mobiles6.Digital Electronics7.Instrumentation

Communications And entertainments

Heinrich Hertz

Industrial Applications

Defence Applications

Applications in Medical sciences

Applications in Auto mobiles

Digital Electronics

Instrumentation

QUIZMSI means………………?Birth of electronics took place in 1897 with the

invention of ……………..?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 COMPONENTSACTIVE 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 componentsRESISTORS

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

RESISTANCEThe ability of resistor to oppose the flow of

current is called Resistance. Unit of resistance R is ohm.

ohm

Types of ResistorsThere are two main Characteristics of

resistance 1.Resistance in ohms2. Power rating in watts FIXED RESISTORS1.Carbon-composition Resistors:Made of mixture of carbon or graphiteAnd clay. Two materials are mixed in the

proportion for the desired value of R.

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 resistorNichrome, tungsten is used for wires.Hollow porcelain cylinderEnds are joined with metal pieces.Assembly is coated with enamel containing powdered Glass.

Resistor colour coding

BBROYGBVGW

QuestionA resistor has a colour band sequence; red,

black, red, goldo first digit----2o second digit—0o third multiplier----100 ohmo gold--------------5%o o result----2000ohm or 2

k ohm with 5% tolerance

Question????

Variable ResistorsSome 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 ResistorWire wound variable Resistor

Carbon composition resistorA 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.

QuizThe electronic component which cannot process

the signal 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

CONTENTSINTRODUCTION TO CRO

FUNCTION GENERATOR

DSO

MULTIMETER (DIGITAL AND ANALOG)

CROCathode 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 AssemblyConsist of heater, focusing anodes and

cathode.

FLOURESCENT SCREENThe 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 SYSTEMTime base generatorTrigger circuitHorizontal amplifier

Time base generatorIt 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 LINEEvery 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 CROBasic 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. 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.

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.

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.

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.

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

WorkingFrequency 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 dtVoi is the linear ramp wave increasing towards

positive as shown in fig.

Ramp voltage is less than upper triggering point(UTP).

Features of Function GeneratorFreq range- 0.01Hz to 100 KHzIt 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)