Electrical Engineering

Modulating signal and carrier Wave   Modulated wave   Frequency spectrum of AM wave   If the equation of modulating signal is

  Voltage to Time A/D converter (Ramp type) Any digital voltmeter has a fundamental cycle sequence which involves sampling, display, and reset sequence. The application of input voltage initiates the measurement cycle. The oscillator is automatically switched with the operator and its output consists of pulses which are counted by an electronic counter. A units counter is first actuated. This units counter provides a carry pulse to the tens counter on using the counter input pulse. In turn, the tens counter provides its own carry pulse after it has counted 10 carry pulses from the units counter. If excess input voltage is being measured, it provides its own carry pulse which switches on a warning lamp. Each decade counter unit in a DVM is counted as a D to A converter. Outputs of a D to A convertor are connected in parallel which build up a comparison voltage. At the instant when the comparison section senses that the input voltage and comparison voltages ar...

  Why we need temperature Measurement ?    

  Introduction   • The last stage of instrumentation & measurement is display devices & recorders. Because the results of a measurement system are meaningful, they must be displayed for instant observation of for storage for observation at a later stage. The first device is called a “ display device ” and the second a “recorder” . The data presentation devices may be called as output devices.

Slide Balanced and unbalanced poly phase

Radio Wave Propagation types

  OUTLINE Modulation and Demodulation Radio Communications Radio Receivers Television Radar

 A bipolar junction transistor consists of three regions of doped semiconductors. A small current in the center or base region can be used to control a larger current flowing between the end regions (emitter and collector). The device can be characterized as a current amplifier, having many applications for amplification and switching  A transistor in a circuit will be in one of three conditions Cut off (no collector current), useful for switch operation. In the active region (some collector current, more than a few tenths of a volt above the emitter), useful for amplifier applications In saturation (collector a few tenths of a volt above emitter), large current useful for "switch on" applications. 

  General Purpose OPAMP Moderate values of the key parameters • Current differencing OPAMP ( have different internal structure) • Non-inverting input is derived from inverting input • Current mirror circuit is used

What is white noise? In communication systems, the noise is an error or undesired random disturbance of a useful information signal, introduced before or after the detector and decoder. The noise is a summation of unwanted or disturbing energy from natural and sometimes man-made sources. Noise is, however, typically distinguished from interference, (e.g. cross-talk, deliberate jamming or other unwanted electromagnetic interference from specific transmitters), for example in the signal-to-noise ratio (SNR), signal-to-interference ratio (SIR) and signal-to-noise plus interference ratio (SNIR) measures. Noise is also typically distinguished from distortion, which is an unwanted alteration of the signal waveform, for example in the signal-to-noise and distortion ratio (SINAD). In a carrier-modulated passband analog communication system, a certain carrier-to-noise ratio (CNR) at the radio receiver input would result in a certain signal-to-noise ratio in the detected message signal...

What is Solid? The sate of matter in which materials are not fluid but retain their boundaries without support and having three dimension (length, breadth and thickness) as a geometric body or figure. Example: » Atomic solid, » Metallic solid, » Molecular solid and  » Ionic solid   Solid can be divided in Crystalline and non- Crystalline of Solid

 A transducer is defined as a device that receives energy from one system and transmits it to another, often in a different form (electrical,mechanical or acoustical). d e e o (e ec ca , ec a ca o acous ca ) „ Basically, there are two types of transducers : 1) Electrical 2) Mechanical „ The electrical output of a transducer depends on the basic principle involved in the design. „ The output may be analog, digital, or frequency modulated

The losses in a dynamo:  When the energy is delivered ta a dynamo ,then not all the energy is available from that dynamo.There are some losses such as- Copper loses Cores losses Mechanical losses 

A Dynamo is a machine for converting rotary motion into electricity. The usual form of dynamo consists of a circular metal frame which is magnetized so as to create a strong magnetic field across the internal space.

Boiler: A boiler or steam generator is a device used to create steam by applying heat energy to water. Fuel used in Boiler: The source of heat for a boiler is combustion of any of several fuels, such as wood, coal, oil, or natural gas. Electric steam boilers use resistance- or immersion-type heating elements. Nuclear fission is also used as a heat source for generating steam. Heat recovery steam generators (HRSGs)use the heat rejected from other processes such as gas turbines. Types of Boiler: There are several types of boiler. Among, few of them given below;

BASIC REFRIGERATION PRINCIPLES If you were to place a hot cup of coffee on a table and leave it for a while, the heat in the coffee would be transferred to the materials in contact with the coffee, i.e. the cup, the table and the surrounding air. As the heat is transferred, the coffee in time cools. Using the same principle, refrigeration works by removing heat from a product and transferring that heat to the outside air.

A reciprocating pump is a positive plunger pump. It is often used where relatively small quantity of liquid is to be handled and where delivery pressure is quite large. Reciprocating pumps can be classified based on 1. Sides in contact with water a) Single acting Reciprocating pump b) Double acting reciprocating pump 2. Numbers of cylinder used a) Single cylinder pump b) Two cylinder pumps c) Multi-cylinder pumps Reciprocating pumps are used in High performance liquid chromatography (HPLC).

The gas turbine is an internal combustion engine that uses air as the working fluid. The engine extracts chemical energy from fuel and converts it to mechanical energy using the gaseous energy of the working fluid (air) to drive the engine and propeller, which, in turn, propel the airplane. THE GAS TURBINE CYCLE The basic principle of the airplane turbine engine is identical to any and all engines that extract energy from chemical fuel. The basic 4 steps for any internal combustion engine are: 1. Intake of air (and possibly fuel). 2. Compression of the air (and possibly fuel). 3. Combustion, where fuel is injected (if it was not drawn in with the intake air) and burned to convert the stored energy. 4. Expansion and exhaust, where the converted energy is put to use. In the case of a piston engine, such as the engine in a car or reciprocating airplane engine, the intake, compression, combustion, and exhaust steps occur in the same place (cylinder head) at different ti...

International Combustion Engine The internal combustion engine is an engine in which the combustion of a fuel (normally a fossil fuel) occurs with an oxidizer (usually air) in a combustion chamber. In an internal combustion engine the expansion of the high-temperature and -pressure gases produced bycombustion applies direct force to some component of the engine, such as pistons, turbine blades, or a nozzle. This force moves the component over a distance, generating useful mechanical energy.

Binary Coding 1. Binary Coded Decimal (BCD) Binary coded decimal (BCD) is a way to express each of the decimal digits with a binary code. There are only ten code groups in the BCD system, so it is very easy to convert between decimal and BCD. Because welike to read and write in decimal, the BCD code provides an excellent interface to binary systems. Examples of such interfaces are keypad inputs and digital readouts. The 8421 Code: The 8421 code is a type of BCD (binary coded decimal) code. Binary coded decimal means that each decimal digit, 0 through 9, is represented by a binary code of four bits. The designation 8421indicates the binary weights of the four bits 2 3 , 2 2 , 2 1 , 2 0 . The ease  of conversion between 8421 code numbers and the familiar decimal numbers is the main advantage of this code.  All wehave to remember are the ten binary combinations that represent the ten decimal digits as shown in Table 1. The 8421 code is the predominant BCD code, and wh...

 Programmable Logic Array (PLA) A combinational circuit may occasionally have don’t care conditions. When implemented with a ROM, a don’t care condition become an address input that will never occur. The words at don’t care addresses need not to be programmed. Why PLA??   Consider for example, a combinational circuit that converts a 12-bit card code to a 6-bit internal alphanumeric code     Valid output = 47 If we use ROM size of ROM = 4096X6 The remaining 4096 words of ROM are not used and are thus wasted

Analysis of clocked sequential circuit   State Table

  A register is a digital circuit with two basic functions    Data storage Data shifting or data transfer or data movement  

Introduction to number systems Representation of numbers with different base  Number base conversion(Base to Base): 1. Decimal Number: (Base-10 System) The decimal system is composed of 10 numbers or symbols. There are 0,1,2,3,4,5,6,7,8,9. Using these symbolsas digits of anumber, we can express any quantity. It is also called Base-10 system as it has 10 digits. Base-10 system comes from the fact that people have 10 fingers. “Digits” is derived from the Latin word “Finger”. The decimal system is a positional-value system in which the value of a digit depends on its position. Consider a decimal number 2745.214 Here,    MSD= Most Significant Digit LSD= Least Significant Digit

Introduction to IC: -Miniature, low-cost electronics circuits whose components are fabricated on a single, continuous piece of semiconductor material to perform a high-level function. -Usually referred to as a monolithic IC. -First introduced in 1958 -Categorized as digital or linear ICs or according to the level of complexity of the IC Category Number of Gates: Small scale integration SSI (<12) Medium scale integration MSI (12 to 99) Large scale integration LSI (100 to 9999) Very large scale integration VLSI (10,000 or more) Classifications of IC logic families: Digital ICs are classified not only by their logic operation, but also by the specific logic-circuit family to which they belong. Each logic family has its own basic electronic circuit upon which more complex digital circuits and functions are developed. The main families are:  TTL(Transistor-Transistor Logic), made of bipolar transistors.   CMOS(Complementary Metal Oxide Semiconductor) made from MOSFETs ...

Problems in MSI Combinational Circuit:   Combinational circuit to add two four bit numbers: Number of input variable = 9   (4+4+carry) Output variables = 5 (4+carry) Possible combination = (2^9) = 512 i.e truth table has 512 entries !!!!

BJT and JFET Frequency Response   Decibels Power and audio levels are related on a log basis. That is an increase of power level, say from 4 to 16 does not increase the audio level by a factor of 16/4=4. rather it will increase the audio level by a factor 0f 2, as obtained by (4) 2 =16. To increase the audio level by a factor 3, the power level should be increased from 4 to (4) 3   = 64.                    Bell is defined by the following equation-   Bell is a too large unit, so decibel is used, as defined by,   dBm   P1 is accepted as 1mW, then

• Water under pressure contains energy. • Turbines convert the energy in water into rotating mechanical energy. • Impulse turbines convert the kinetic energy of a jet of water to mechanical energy. • Reaction turbines convert potential energy in pressurized water to mechanical energy. Impulse Turbines • Tolerate sand. • Easy to fabricate. • Efficient at wide a range of head and flow. • Anozzle convertspressurised water into a high-speed jet of water. •Pelton –LowFlow –Medium to High Head •Turgo –Medium Flow –Medium to High Head • Crossflow –HighFlow –Low to Medium Head Pelton Turbines    • At least one jet of water strike the buckets at atmospheric pressure. • Maximum jet diameter about 1/3 bucket width. • More jets increase flow and are used at low head.                               ...

  What is Signal?   • A signal is a physical quantity which varies with respect to time, space and contains information from source to destination. • Example: Audio signal, video signal, speech signal, image signal, communication signal, geophysical signal, radar signal, medical signal and musical signals.   Signal Processing • Signal processing deals with operations of signal or analysis of signals, or measurements of time-varying or spatially varying physical quantities.

Filter It is an electronic circuit used to separate out signals of different frequencies. Types : (1) High Pass (2) Low Pass (3) Band Pass or Notch                                                                    (4) Band reject

  Historical review • Early history of communication • 1799 Alessandro Volta invented electric battery, •1837 Samuel Morse demonstrated telegraph and 1844 first telegraph line (Washington-Baltimore) became operational •Early history of wireless communication •1831 Faraday demonstrates electromagnetic induction •J. Maxwell (1831-79): theory of electromagnetic Fields, wave equations (1864) •H. Hertz (1857-94): demonstrates with an experiment the wave character of electrical transmission through space(1888, in Karlsruhe,Germany, at the location of today’s University of Karlsruhe)     —   Historical review    Early history of wireless communication I     1895 Guglielmo Marcon      first demonstration of wireless telegraphy (digital!)      long wave transmission, high  transmission power  necessary (> 200kw)

Oscillator • Positive feed back in an amplifier results in oscillator .

Generally, an amplifier or simply amp, is any device that changes, usually increases, the amplitude of a signal.  An Amplifier receives a signal from some pickup transducer or other input source and provides a larger version of the signal to some output device or to another amplifier stage. An input transducer signal is generally small (a few millivolts from a cassette or CD input or a few microvolts from an antenna) and needs to be amplified sufficiently to operate an output device (speaker or other power-handling device). In small signal amplifiers, the main factors are usually amplification linearity and magnitude of gain , since signal voltage and current are small in a small-signal amplifier, the amount of power-handling capacity and power efficiency are of little concern. A voltage amplifier provides voltage amplification primarily to increase the voltage of the input signal. Large-signal or power amplifiers, on the other hand, primarily provide sufficient power to a...

An induction machine is the most simple electrical machine from constructional point of view, in most of the cases. It can be classified into motor and generator. In this post, I want to discuss the characteristic common to both of these. Detailed description of each will be available soon in other posts. Induction machines work on induction principle, in other words it depends on Faraday's law of induction (i.e. when a conductor moves in a magnetic field, it gets some voltage(induced voltage). this voltage can set up current if construction permits and can set up its own magnetic field.). In this case it should be noted that moving in a magnetic field actually makes the magnetic flux changing to the moving conductor(actually seems to be changing, from the view point of one who is moving), and this changing magnetic field causes voltage and current to be induced on the moving body. But if the magnetic filed is itself changing in nature, then it can induce voltage...

JFET Biasing • Fixed Bias Configuration • Self Bias Configuration • Voltage Divider Biasing JFET Self-Bias Configuration   • In fixed bias configuration an extra resistance R S is added. • Like self bias configuration we can neglect RG, capacitors

Principle:     It is based on the principle that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force whose direction is given by Fleming's Left-hand rule and whose magnitude is given by                      Force, F = B I l newton                             Where B is the magnetic field in weber/m 2 .                                  I is the current in amperes and                            ...

 Single-phase electric power refers to the distribution of electric power using a system in which all the voltages of the supply vary in unison. Single-phase distribution is used when loads are mostly lighting and heating, with few large elec...

 A transformer is a static electrical device that transfers energy by inductive coupling between its winding circuits. The transformer is one of the simplest of electrical devices. Its basic design, materials, and principles have changed little over the last one hundred years, yet transformer designs and materials continue to be improved. Transformers are essential in high voltage power transmission providing an economical means of transmitting power over large distances. The simplicity, reliability, and economy of conversion of voltages by transformers was the principal factor in the selection of alternating current power transmission in the "War of Currents" in the late 1880's. In electronic circuitry, new methods of circuit design have replaced some of the applications of transformers, but electronic technology has also developed new transformer designs and applications. Transformers come in a range of sizes from a thumbnail-sized coupling transfo...

In modern power systems isolated generators are veryrare. Power systems are highly interconnected and many generators share the load. The first problem of an engineer is connectinga synchronous generator onan existingbus.   CONNECTING a GENERATOR to a BUS The above figure  illustrates a generator G1 which is already connected to a power grid under load. Generator 2 has to be connected or “brought on line” 1.  The prime mover of the generator has to bringthe speed of the shaft close to the rated speed of the generator. 2.  The excitation of the generator has to be increasedto give a no-load output voltage as close as possible to the existingbus voltage We want to create a phasor rotation for generator 2 output similar to the bus voltage phasor. 3.  Observe the lights which are connected across the switches: theyshould beat, first get brighter and then dimas the phasors for generator and bus respectivelyshift. If the 3 lights beat concurrently...

Two types : 1. Positive feedback, drives into oscillation. 2 .Negative feedback, reduces overall gain but a number of improvements are obtained. Improvements due to negative feedback : 1. Higher input impedance 2. Better stabilized voltage gain 3. Improved frequency response 4. Lower output impedance 5. Reduced noise 6. More linear operation Feedback amplifier