Identification, Specification & Testing of Components and Equipment’s

Aim:

1. To identify the different component symbols.
2. To study and operation of multimeter, function generator, and regulated power supply.
3. To observe front panel control knobs and to find amplitude, time period and frequency for given waveform.

Apparatus:

1. Resistors
2. Capacitors
3. Inductors
4. Transformers
5. Diodes
6. Transistors
7. Multimeter
8. Function generator
9. Regulated power supply
10. Cathode ray oscilloscope

Theory:

Resistors:

Opposition to flow of currents is called resistance. The elements having resistance are called resistors. They are of two types

1. Fixed Resistor
2. Variable Resistor

Specifications:

1. Resistance value: This is the value of the resistance expressed in ohms. Ex: 10O, 1MO

2. Tolerance:   This is the variation in the value of the resistance i.e. expected from exact indicated value usually tolerance is represented in % ex: 1%, 2%, 20%.   

3. Power rating: The power rating is very important in the sense that it determines the maximum correct that a resistor can withstand without being destroyed. The power rating of resistor is specified as so many watts at a specific temperature such as one or two watts at 70 degree.

Capacitors:

A capacitor (originally known as condenser) is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric (insulator); for example, one common construction consists of metal foils separated by a thin layer of insulating film. Capacitors are widely used as parts of electrical circuits in many common electrical devices. They are of three types

1. Disk capacitor
2. Fixed capacitor
3. Variable capacitor

Inductors:

An inductor (also choke, coil, or reactor) is a passive two-terminal electrical component that stores energy in its magnetic field. For comparison, a capacitor stores energy in an electric field, and a resistor does not store energy but rather dissipates energy as heat.

Any conductor has inductance. An inductor is typically made of a wire or other conductor wound into a coil, to increase the magnetic field.

Inductor value: 

The inductance is defined as the ability of an inductor which opposes the change in current. It is denoted by the letter “L” and its unit is Henry (H).Ex:1H.2H…

Mutual inductance:

It is the ability of a varying current in one inductor L1 induced voltage in another inductor L2 nearby. It is represented by Lm and is measured in Henry.

M = K√ (L1XL2) H

Coefficient if coupling:

It is defined as the ratio of flux linkages between L1 and L2. To total flux produced by L1. It is represented by K and its typical value is 1.

K = Lm/√ (L1XL2)

Permeability: 

It is denoted by micro’s” and it is return as R = B/H. Where B = flux density, H = Flux intensity 

Transformers:

A transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. A varying current in the primary winding creates a varying magnetic flux in the transformer's core and thus a varying magnetic flux through the secondary winding. This varying magnetic flux induces a varying electromotive force (emf) or voltage in the secondary winding. They are of two types

1. Step up transformer
2. Step down transformer

Diodes

In electronics, a diode is a two-terminal electronic component with an asymmetric transfer characteristic, with low (ideally zero) resistance to current flow in one direction, and high (ideally infinite) resistance in the other. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material with a p–n junction connected to two electrical terminals. A vacuum tube diode is a vacuum tube with two electrodes, a plate (anode) and heated cathode.

In this lab we will find the characteristics of

1. P-N junction diode
2. Zener diode

P N junction diode

A p–n junction is a boundary or interface between two types of semiconductor material, p-type and n-type, inside a single crystal of semiconductor. It is created bydoping, for example by ion implantation, diffusion of dopants, or by epitaxy (growing a layer of crystal doped with one type of dopant on top of a layer of crystal doped with another type of dopant). If two separate pieces of material were used, this would introduce a grain boundary between the semiconductors that severely inhibits its utility by scattering the electrons and holes.

Zener Diode

A Zener diode is a diode which allows current to flow in the forward direction in the same manner as an ideal diode, but will also permit it to flow in the reverse direction when the voltage is above a certain value known as the breakdown voltage, "zener knee voltage", "zener voltage" or "avalanche point".

The device was named after Clarence Zener, who discovered this electrical property. Many diodes described as "zener" diodes rely instead on avalanche breakdown as the mechanism. Both types are used. Common applications include providing a reference voltage for voltage regulators, or to protect other semiconductor devices from momentary voltage pulses.

Transistors

A transistor is a semiconductor device used to amplify and switch electronic signals and electrical power. It is composed of semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current through another pair of terminals. Because the controlled (output) power can be higher than the controlling (input) power, a transistor can amplify a signal. Today, some transistors are packaged individually, but many more are found embedded in integrated circuits.

The term transistor was coined by John R. Pierce as a portmanteau of the term "transfer resistor.

The transistor is the fundamental building block of modern electronic devices, and is ubiquitous in modern electronic systems. Following its development in the early 1950s, the transistor revolutionized the field of electronics, and paved the way for smaller and cheaper radios, calculators, and computers, among other things.

Transistors types

1. Bipolar Transistor    Example: Bipolar junction transistor
2. Unipolar Transistor   Example: Field effect transistor, Uni junction transistor

Bipolar junction transistor

A bipolar junction transistor (BJT or bipolar transistor) is a type of transistor that relies on the contact of two types of semiconductor for its operation

Bipolar transistors are so named because their operation involves both electrons and holes. These two kinds of charge carriers are characteristic of the two kinds of doped semiconductor material

Charge flow in a BJT is due to bidirectional diffusion of charge carriers across a junction between two regions of different charge concentrations. The regions of a BJT are called emitter, collector, and base.

A BJT consists of three differently doped semiconductor regions, the emitter region, the base region and the collector region. These regions are, respectively, p type, n type and p type in a PNP transistor, and n type, p type and n type in an NPN transistor. Each semiconductor region is connected to a terminal, appropriately labeled: emitter (E), base (B) and collector (C).

Field effect transistor

The field-effect transistor (FET) is a transistor that uses an electric field to control the shape and hence the conductivity of a channel of one type of charge carrier in a semiconductor material.

FETs can be majority-charge-carrier devices, in which the current is carried predominantly by majority carriers, or minority-charge-carrier devices, in which the current is mainly due to a flow of minority carriers. The device consists of an active channel through which charge carriers, electrons or holes, flow from the source to the drain. Source and drain terminal conductors are connected to the semiconductor through ohmic contacts. The conductivity of the channel is a function of the potential applied across the gate and source terminals.

The FET's three terminals are:

1. Source (S), through which the carriers enter the channel. Conventionally, current entering the channel at S is designated by I_S.
2. Drain (D), through which the carriers leave the channel. Conventionally, current entering the channel at D is designated by I_D. Drain to Source voltage is V_DS.
3. Gate (G), the terminal that modulates the channel conductivity. By applying voltage to G, one can control I_D.

Types of FET

1. Junction FET(JFET).

   i) N-Channel JFET

   ii) P-Channel JFET

2. Metal oxide semiconductor FET (MOSFET)

MOSFET types

1) Depletion MOSFET

   i) N-Channel MOSFET

   ii) P-Channel MOSFET

2) Enhancement MOSFET

   i) N-Channel MOSFET

   ii) P-Channel MOSFET

Circuit Diagram

Resistor symbols

Capacitor Symbols

Inductor symbols

Transformer symbols

Switches

Diodes symbols

Transistors symbols

BJT types

FET types

Breadboard

A breadboard (or protoboard) is a construction base for prototyping of electronics. The term "breadboard" is commonly used to refer to a solderless breadboard (plugboard).

Because the solderless breadboard does not require soldering, it is reusable. This makes it easy to use for creating temporary prototypes and experimenting with circuit design. Older breadboard types did not have this property. A stripboard (veroboard) and similar prototypingprinted circuit boards, which are used to build permanent soldered prototypes or one-offs, cannot easily be reused. A variety of electronic systems may be prototyped by using breadboards, from small analog and digital circuits to complete central processing units(CPUs).

Series connection 

Parallel connection

When a capacitor is being discussed, it is referred to with certain "specifications" or characteristics. Capacitors are usually "specified" in the following manner-

• They are specified by type (tantalum, electrolytic, etc.)
• They are specified by package (axial, radial, as discussed above).
• They are specified by how to connect to them, their connection type (such as "snap in" or leaded or threaded screw holes, or surface mount).
• They are specified by capacitance value, e.g. in microfarads (µF).
• They are specified by voltage rating (i.e., 30 V). This indicates the maximum voltage under which it is safe to use the referenced capacitor.
• Some types, such as electrolytic capacitors, are specified by operating temperature (usually 80 or 120 °C), which reflects the maximum temperature that the capacitor can reach before failing. Note- common practice is to use capacitors well below their maximum operating voltage and temperature in order to ensure longevity.
• They can be specified by other parameters, including ESR or "equivalent series resistance" (explained above). Also, some capacitors can be specified by UL or other safety rating. A "X" type capacitor indicates that the capacitor meets certain standards one of which is that it is appropriate to be used with line-level voltages (such as 117 or 220 V) typically found from the wall outlet, as well as that it can withstand surges typically found in power distribution systems.
• They are specified in percentage accuracy, i.e., how much they are likely to deviate from their rated capacitance. Common ratings are + or - 20%.

Regulated power supply

A regulated power supply is an embedded circuit, or stand alone unit, the function of which is to supply a stable voltage (or less often current), to a circuit or device that must be operated within certain power supply limits. The output from the regulated power supply may be alternating or unidirectional, but is nearly always DC (Direct Current) .

The type of stabilization used may be restricted to ensuring that the output remains within certain limits under various load conditions, or it may also include compensation for variations in its own supply source. The latter is much more common today.

Function generator

A function generator is usually a piece of electronic test equipment or software used to generate different types of electrical waveforms over a wide range of frequencies. Some of the most common waveforms produced by the function generator are the sine, square, triangular and sawtooth shapes. These waveforms can be either repetitive or single-shot (which requires an internal or external trigger source). Integrated circuits used to generate waveforms may also be described as function generator ICs. 

Although function generators cover both audio and RF frequencies, they are usually not suitable for applications that need low distortion or stable frequency signals. When those traits are required, other signal generators would be more appropriate.

Some function generators can be phase-locked to an external signal source (which may be a frequency reference) or another function generator.

Function generators are used in the development, test and repair of electronic equipment. For example, they may be used as a signal source to test amplifiers or to introduce an error signal into a control loop.

Designation	Specification
Waveform	Sin, square and triangular
Amplitude	0-20V
Frequency range	0.1Hz to 1MHz
Offset	Continuously variable 10V
Output impedance	600ohms,5%

Range selector is used to select the range of frequency

Digital Multimeter

A multimeter or a multitester, also known as a VOM (Volt-Ohm meter), is an electronic measuring instrument that combines several measurement functions in one unit. A typical multimeter would include basic features such as the ability to measure voltage, current, and resistance. Analog multimeters use a microammeter whose pointer moves over a scale calibrated for all the different measurements that can be made. Digital multimeters (DMM, DVOM) display the measured value in numerals, and may also display a bar of a length proportional to the quantity being measured. Digital multimeters have all but replaced analog moving coil multimeters in most situations. Analog multimeters are still manufactured but by few manufacturers.

Quantities measured

Contemporary multimeters can measure many quantities. The common ones are:

• Voltage, alternating and direct, in volts.
• Current, alternating and direct, in amperes.
• The frequency range for which AC measurements are accurate must be specified.
• Resistance in ohms.

Additionally, some multimeters measure:

• Capacitance in Farads.
• Conductance in Siemens.
• Decibels.
• Duty cycle as a percentage.
• Frequency in Hertz.
• Inductance in Henrys.
• Temperature in degrees Celsius or Fahrenheit, with an appropriate temperature test probe, often a thermocouple.

Digital multimeters may also include circuits for:

• Continuity tester; sounds when a circuit conducts
• Diodes (measuring forward drop of diode junctions), and transistors (measuring current gain and other parameters)
• Battery checking for simple 1.5 volt and 9 volt batteries. This is a current loaded voltage scale which simulates in-use voltage measurement.

Cathode Ray Oscilloscope

An oscilloscope, previously called an oscillograph, and informally known as a scope,CRO (for cathode-ray oscilloscope), or DSO (for the more modern digital storage oscilloscope), is a type of electronic test instrument that allows observation of constantly varying signal voltages, usually as a two-dimensional graph of one or more electrical potential differences using the vertical or y-axis, plotted as a function of time (horizontal or x-axis). Many signals can be converted to voltages and displayed this way. Signals are often periodic and repeat constantly, so that multiple samples of a signal which is actually varying with time are displayed as a steady picture. Many oscilloscopes (storage oscilloscopes) can also capture non-repeating waveforms for a specified time, and show a steady display of the captured segment.

Oscilloscopes are commonly used to observe the exact wave shape of an electrical signal. Oscilloscopes are usually calibrated so that voltage and time can be read as well as possible by the eye. This allows the measurement of peak-to-peak voltage of a waveform, the frequency of periodic signals, the time between pulses, the time taken for a signal to rise to full amplitude (rise time), and relative timing of several related signals.

Oscilloscopes are used in the sciences, medicine, engineering, and telecommunications industry. General-purpose instruments are used for maintenance of electronic equipment and laboratory work. Special-purpose oscilloscopes may be used for such purposes as analyzing an automotive ignition system, or to display the waveform of the heartbeat as an electrocardiogram. Some computer sound software allows the sound being listened to be displayed on the screen as by an oscilloscope.

Before the advent of digital electronics oscilloscopes used cathode ray tubes as their display element (hence were commonly referred to as CROs) and linear amplifiers for signal processing. More advanced storage oscilloscopes used special storage CRTs to maintain a steady display of a single brief signal. CROs were later largely superseded by digital storage oscilloscopes (DSOs) with thin panel displays, fast analog-to-digital converters and digital signal processors. DSOs without integrated displays (sometimes known as digitisers) are available at lower cost, and use a general-purpose digital computer to process and display waveforms.

CRO

The main parts are 

1. Electron gun:  it is used to produce sharply focused beam of electron accelerated to very high velocity.
2. Deflection system:  it deflects the electron both in horizontal and vertical plan.
3. Florescent screen: the screen which produces, spot of visible light . when beam of electrons are incident on it the other side of tube is coated with phosphorus material. 

FRONT PANNEL:

ON-POWER: toggle switch for switching on power.

INTENCITY: controls trace intensity from zero to maximum.

 FOCUS: It controls sharpness of trace a slight adugestement of focus is done after changing intensity of trace.

AC-DC: GROUND:

It selects coupling of ACDC ground signal to vertical amplifier.

 X-MAG: It expands length of time base from 15 times continuously and to maximum time base to 40 ns/cm.

SQUARE: This provides square wave 2v (pP) amplitude and enables to check y calibration of scope.

SAWTOOTH WAVE FORM:  This provides saw tooth wave form output coincident to sweep speed with an output of saw tooth wave (pp) 

VERTICAL SECTION: y position:

This enables movement of display along y-axis.

Y-INPUT: It connects input signal to vertical amplifier through ACDC ground coupling switch 

CALIBRATION: 15mv – 150mv dc signal depending on position selection is applied to vertical amplifier. 

 DC BALANCE: It is control on panel electrostatic ally in accordance with waveforms to be displayed.

VOLTS/CM: Switch adjusts sensitivity.

 HORIZANTAL SECTION:

X-POSITION: This control enables movement of display along xaxis.

TRIGGERING LEVEL: It selects mode of triggering.

TIMEBASE: This controls or selects sweep speeds.

VERNUIS: This control the fine adjustments associated with time base sweep.

 SIGN SELECTOR: It selects different options of INT/EXT, NORM/TO.

STAB: Present on panel

EXITCAD: It allows time base range to be extended.

HORIZANTAL INPUT: It connects external signal to horizontal amplifier.

Ext SYN: it connects external signal to trigger circuit for synchronization.

OBSERVATIONS:

Amplitude = no. of vertical divisions * Volts/div.

Time period = no. of horizontal divisions * Time/div.

Frequency = 1/T

Amplitude taken on vertical section (y).

Time period taken on horizontal section(x)

Model waveforms

Measurement of Phase