Elec Answers

8/12/2019 Elec Answers

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12. What is emitter follower?

Ans 1: In electronics, a common-collector amplifier is one of three basic single-stagebipolar junction transistor amplifier topologies, typically used as a voltage buffer. ...

Ans 2: In electronics , a common collector amplifier (also known as an emitterfollower ) is one of three basic single-stage bipolar junction transistor (BJT) amplifitopologies , typically used as a voltage buffer .

In this circuit the base terminal of the transistor serves as the input, the emitter isthe output, and the collector is common to both (for example, it may be tied toground reference or a power supply rail ), hence its name. The analogous field-effetransistor circuit is the common drain amplifier.

Figure 1: Basic NPN common collector circuit (neglecting biasing details).

Ans 3: Emitter Follower An emitter follower circuit shown in the figure is widely used in AC amplificationcircuits. The input and output of the emitter follower are the base and the emitter,respectively, while the collector is at AC zero, therefore this circuit is also calledcommon-collector circuit.
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13. Give the electromagnetic equations in the order of discovery.

Ans: Maxwell's Equations are a set of 4 complicated equations that describe theworld of electromagnetics. These equations describe how electric and magneticfields propagate, interact, and how they are influenced by objects.

James Clerk Maxwell [1831-1879] was an Einstein/Newton-level genius who took aset of known experimental laws (Faraday's Law, Ampere's Law) and unified theminto a symmetric coherent set of Equations known as Maxwell's Equations. Maxwellwas one of the first to determine the speed of propagation of electromagnetic (EM)waves was the same as the speed of light - and hence to conclude that EM wavesand visible light were really the same thing.

Maxwell's Equations are critical in understanding Antennas and Electromagnetics.They are formidable to look at - so complicated that most electrical engineers andphysicists don't even really know what they mean. Shrouded in complex math(which is likely so "intellectual" people can feel superior in discussing them), true

understanding of these equations is hard to come by.This leads to the reason for this website - an intuitive tutorial of Maxwell's Equations.I will avoid if at all possible the mathematical difficulties that arise, and insteaddescribe what the equations mean. And don't be afraid - the math is so complicatedthat those who do understand complex vector calculus still cannot apply Maxwell'sEquations in anything but the simplest scenarios. For this reason, intuitiveknowledge of Maxwell's Equations is far superior than mathematical manipulation-based knowledge. To understand the world, you must understand what equationsmean, and not just know mathematical constructs. I believe the accepted methods

of teaching electromagnetics and Maxwell's Equations do not produceunderstanding. And with that, let's say something about these equations.

Maxwell's Equations are laws - just like the law of gravity. These equations are rulesthe universe uses to govern the behavior of electric and magnetic fields. A flow ofelectric current will produce a magnetic field. If the current flow varies with time (asin any wave or periodic signal), the magnetic field will also give rise to an electricfield. Maxwell's Equations shows that separated charge (positive and negative)gives rise to an electric field - and if this is varying in time as well will give rise to apropagating electric field, further giving rise to a propgating magnetic field.

To understand Maxwell's Equations at a more intuitive level than most Ph.Ds inEngineering or Physics, click through the links and definitions above. You'll find thatthe complicated math masks an inner elegance to these equations - and you'll learnhow the universe operates the Electromagnetic Machine.
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The equations have two major variants. The "microscopic" set of Maxwell'sequations uses total charge and total current, including the complicated chargesand currents in materials at the atomic scale; it has universal applicability, but maybe unfeasible to calculate. The "macroscopic" set of Maxwell's equations definestwo new auxiliary fields that describe large-scale behavior without having toconsider these atomic scale details, but it requires the use of parameterscharacterizing the electromagnetic properties of the relevant materials.

The term "Maxwell's equations" is often used for other forms of Maxwell's equations.For example, space-time formulations are commonly used in high energy andgravitational physics. These formulations, defined on space-time rather than space

and time separately, are manifestly[note 1]

compatible with special and generalrelativity . In quantum mechanics, versions of Maxwell's equations based on theelectric and magnetic potentials are preferred.

Since the mid-20th century, it has been understood that Maxwell's equations are notexact laws of the universe, but are a classical approximation to the more accurateand fundamental theory of quantum electrodynamics . In most cases, though,quantum deviations from Maxwell's equations are immeasurably small. Exceptionsoccur when the particle nature of light is important or for very strong electric fields.

Conceptual descriptions (wiki)Gauss's law Gauss's law describes the relationshipbetween a static electric field and the electric charges that cause it: The staticelectric field points away from positive charges and towards negative charges. Inthe field line description, electric field lines begin only at positive electric chargesand end only at negative electric charges. 'Counting' the number of field linespassing though a closed surface , therefore, yields the total charge (including boundcharge due to polarization of material) enclosed by that surface divided bydielectricity of free space (the vacuum permittivity ). More technically, it relates theelectric flux through any hypothetical closed "Gaussian surface " to the enclosedelectric charge.
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Gauss's law for magnetism : magnetic field lines never begin nor end but form loopsor extend to infinity as shown here with the magnetic field due to a ring of current.

Gauss's law for magnetism

Gauss's law for magnetism states that there are no "magnetic charges" (alsocalled magnetic monopoles ), analogous to electric charges .[3] Instead, the magneticfield due to materials is generated by a configuration called a dipole . Magneticdipoles are best represented as loops of current but resemble positive and negative'magnetic charges', inseparably bound together, having no net 'magnetic charge'. Interms of field lines, this equation states that magnetic field lines neither begin norend but make loops or extend to infinity and back. In other words, any magnetic fieldline that enters a given volume must somewhere exit that volume. Equivalenttechnical statements are that the sum total magnetic flux through any Gaussiansurface is zero, or that the magnetic field is a solenoidal vector field .

Faraday's law

In a geomagnetic storm , a surge in the flux of charged particles temporarily altersEarth's magnetic field, which induces electric fields in Earth's atmosphere, thuscausing surges in electrical power grids . Artist's rendition; sizes are not to scale.

Faraday's law describes how a time varying magnetic field creates ("induces") anelectric field .[3] This dynamically induced electric field has closed field lines just asthe magnetic field, if not superposed by a static (charge induced) electric field. Thisaspect of electromagnetic induction is the operating principle behind many electricgenerators : for example, a rotating bar magnet creates a changing magnetic field,which in turn generates an electric field in a nearby wire. (Note: there are twoclosely related equations which are called Faraday's law. The form used inMaxwell's equations is always valid but more restrictive than that originallyformulated by Michael Faraday .)

Ampre's law with Maxwell's correction An Wang 's magnetic core memory (1954) is an application of Ampre's law . Eachcore stores one bit of data.

Ampre's law with Maxwell's correction states that magnetic fields can begenerated in two ways: by electrical current (this was the original "Ampre's law")and by changing electric fields (this was "Maxwell's correction").

Maxwell's correction to Ampre's law is particularly important: it shows that not onlydoes a changing magnetic field induce an electric field, but also a changing electricfield induces a magnetic field .[3][4] Therefore, these equations allow self-sustaining"electromagnetic waves " to travel through empty space (see electromagnetic waveequation ).
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etic_fluxhttp://en.wikipedia.org/wiki/Dipolehttp://en.wikipedia.org/wiki/Maxwell%27s_equations#cite_note-VideoGlossary-4http://en.wikipedia.org/wiki/Magnetic_monopolehttp://en.wikipedia.org/wiki/Gauss%27s_law_for_magnetismhttp://en.wikipedia.org/wiki/Gauss%27s_law_for_magnetism


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The speed calculated for electromagnetic waves, which could be predicted fromexperiments on charges and currents ,[note 2] exactly matches the speed of light ; indeed, light is one form of electromagnetic radiation (as are X-rays , radio waves ,and others). Maxwell understood the connection between electromagnetic wavesand light in 1861, thereby unifying the theories of electromagnetism and optics .

Vacuum equations, electromagnetic waves and speed of lightFurther information: Electromagnetic wave equation and Sinusoidal plane-wavesolutions of the electromagnetic wave equation

This 3D diagram shows a plane linearly polarized wave propagating from left to rightwith the same wave equations where E = E 0 sin( t + k r ) and B = B0 sin( t +r )

In a region with no charges ( = 0) and no currents ( J = 0), such as in a vacuum,Maxwell's equations reduce to:

Taking the curl ( ) of the curl equations, and using the curl of the curl identity (X) = ( X) 2X we obtain the wave equations

which identify

with the speed of light in free space. In materials with relative permittivity r andrelative permeability r , the phase velocity of light becomes

which is usually less than c .

In addition, E and B are mutually perpendicular to each other and the direction ofwave propagation, and are in phase with each other. A sinusoidal plane wave is onespecial solution of these equations. Maxwell's equations explain how these wavescan physically propagate through space. The changing magnetic field creates a

changing electric field through Faraday's law . In turn, that electric field creates a
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changing magnetic field through Maxwell's correction to Ampre's law . Thisperpetual cycle allows these waves, now known as electromagnetic radiation , tomove through space at velocity c .

13.Find the transfer function of a given RLC circuit.

Teja wil do the answer

14. What happens when you type user-name and password while logging on to aUnix system?

Ans: When you log in, you identify yourself to the computer. On modern Unixes youwill usually do this through a graphical display manager. But it's possible to switchvirtual consoles with a Ctrl-Shift key sequence and do a textual login, too. In thatcase you go through the getty instance watching that console tto call the programlogin .

You identify yourself to the display manager or login with a login name and

password. That login name is looked up in a file called /etc/passwd, which is asequence of lines each describing a user account.

One of these fields is an encrypted version of the account password (sometimes theencrypted fields are actually kept in a second /etc/shadow file with tighterpermissions; this makes password cracking harder). What you enter as an accountpassword is encrypted in exactly the same way, and the login program checks tosee if they match. The security of this method depends on the fact that, while it'seasy to go from your clear password to the encrypted version, the reverse is veryhard. Thus, even if someone can see the encrypted version of your password, theycan't use your account. (It also means that if you forget your password, there's noway to recover it, only to change it to something else you choose.)

Once you have successfully logged in, you get all the privileges associated with theindividual account you are using. You may also be recognized as part of a group . group is a named collection of users set up by the system administrator. Groups canhave privileges independently of their members privileges. A user can be a memberof multiple groups. (For details about how Unix privileges work, see the sectionbelow on permissions .)

(Note that although you will normally refer to users and groups by name, they areactually stored internally as numeric IDs. The password file maps your accountname to a user ID; the /etc/group file maps group names to numeric group IDs.Commands that deal with accounts and groups do the translation automatically.)

Your account entry also contains your home directory , the place in the Unix filesystem where your personal files will live. Finally, your account entry also sets yourshell , the command interpreter that login will start up to accept your commmands.
http://en.wikipedia.org/wiki/Amp%C3%A8re%27s_circuital_lawhttp://en.wikipedia.org/wiki/Amp%C3%A8re%27s_circuital_lawhttp://en.wikipedia.org/wiki/Amp%C3%A8re%27s_circuital_lawhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://www.tldp.org/HOWTO/Unix-and-Internet-Fundamentals-HOWTO/disk-layout.html#permissionshttp://www.tldp.org/HOWTO/Unix-and-Internet-Fundamentals-HOWTO/disk-layout.html#permissionshttp://www.tldp.org/HOWTO/Unix-and-Internet-Fundamentals-HOWTO/disk-layout.html#permissionshttp://www.tldp.org/HOWTO/Unix-and-Internet-Fundamentals-HOWTO/disk-layout.html#permissionshttp://en.wikipedia.org/wiki/Electromagnetic_radiationhttp://en.wikipedia.org/wiki/Amp%C3%A8re%27s_circuital_law


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What happens after you have successfully logged in depends on how you did it. Ona text console, login will launch a shell and you'll be off and running. If you loggedin through a display manager, the X server will bring up your graphical desktop andyou will be able to run programs from it either through the menus, or throughdesktop icons, or through a terminal emulator running a shell .

Ans 2: Finish entering your username by pressing Enter or Return.

After you type your username, UNIX asks you to enter your password, which youtype the same way and end by pressing Enter. Because your password is secret, itdoesn't appear on-screen as you type it. How can you tell whether you've typed itcorrectly? You can't! If UNIX agrees that you've typed your username and passwordacceptably, it displays a variety of uninteresting legal notices and a message fromyour system administrator (usually delete some files, the disk is full) and passes youon to the shell.

15. Draw the circuit for an adder using NAND gates.

Half Adder using NAND gate only

Full Adder using NAND gate only

To construct a full adder circuit, well need three inputs and two outputs. Since well have both an inputcarry and an output carry, well designate them as C IN and C OUT . At the same time, well use S to designatethe final Sum output. The resulting truth table is shown to the right.

Hmmm. This is looking a bit messy. It looks as if C OUT may be either an AND or an OR function,depending on the value of A, and S is either an XOR or an XNOR, again depending on the value of A.Looking a little more closely, however, we can note that the S output is actually an XOR between the Ainput and the half-adder SUM output with B and C IN inputs. Also, the output carry will be true if any two orall three inputs are logic 1.

What this suggests is also intuitively logical: we can use two half-adder circuits. The first will add A and Bto produce a partial Sum, while the second will add C IN to that Sum to produce the final S output. If eitherhalf-adder produces a carry, there will be an output carry. Thus, C OUT will be an OR function of the half-adder Carry outputs. The resulting full adder circuit is shown here ( fig 3.2 not available).
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fig 3.3

Using only NAND gates

16. Explain internal organization of memory chips.

Ans:

Organization of a 1K 1 memory chip.


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Ans 2: Internal Organization of Memory Chips

16. What are the different types of control systems? Answer check with teja

Ans: Types of Control SystemsThere are two types of control systems namely:

1. Open loop (feedback )2. Closed loop (non-feedback)

Open loop

If in a physical system there is no automatic correction of the variation in its output, it is called anopen loop control system. That is, in this type of system, sensing of the actual output and

comparing of this output (through feedback) with the desired input doesn't take place. The system


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on its own is not in a position to give the desired output and it cannot take into account thedisturbances. In these systems, the changes in output can be corrected only by changing the inputmanually.

These are simple in construction, stable and cost cheap. But these are inaccurate and unreliable.Moreover these systems don't take account of external disturbances that affect the output andthey don't initiate corrective actions automatically.

Examples of open loop control:

1. Automatic washing machine2. Traffic signal3. Home heating (without sensing, feedback and control)

Any non-feedback can be considered as a feedback CS if it is under the supervision of someone. Although open loop control systems have economical components and are simple in design, theylargely depend on human judgment. As an example, let us consider a home furnace controlsystem. This system must control the temperature in a room, keeping it constant. An open loopsystem usually has a timer which instructs the system to switch on the furnace for some time andthen switch it off. Accuracy cannot be achieved as the system doesn't switch on/off based on theroom temperature but it does as per the preset value of time.

Closed loop

A closed loop is a system where the output has an effect upon the input quantity in such a manneras to maintain the desired output value.

A normal system becomes a closed loop control by including a feedback. This feedback willautomatically correct the change in output due to disturbances. This is why a closed loop control iscalled as an automatic control system.

In a closed loop, the controlled variable (output) is sensed at every instant of time, feedback andcompared with the desired input resulting in an error signal. This error signal directs the controlelements in the system to do the necessary corrective action such that the output of the system isobtained as desired.

17. Explain open loop with block diagram examples

Control Systems

1 Different types of systemsAll our tools and machines need appropriate control to work, otherwise it will be difficult tofinish their designated tasks accurately. Therefore, we need control systems to guide, instruct andregulate our tools and machines. Common control systems include mechanical, electronic,

pneumatic and computer aided. A system usually contains three main parts: input, process andoutput.

(a) Mechanical systemA mechanical system is a device made up of various mechanical parts. Its input is provided by


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an effort. Once the effort and is applied, it can set off a motion to move a load. The force appliedto the load is the output of the mechanical system. Examples of mechanical systems include levers,gears and shafts. Fig. 1 shows some examples of mechanical systems.(a) Can opener (b) Corkscrew

(b) Electronic systemAn electronic system is a system that employs electronic signals to control devices, such asradios, calculators, video game machines, mobile phones, portable computers, etc (Fig. 2). The inputof an electronic system is provided by electronic signals. After they are processed, they can generateoutput signals, which control the operation of various devices, such as amplifiers and LCD.Electronic systems can carry out many different tasks, such as generating sound, transmittinginformation, displaying video, measuring, memorising, calculating, etc. Common examples ofelectronic devices include semi-conducting diode, transistors, capacitors that they are usually weldedonto electronic circuit boards(a) Mobile phone (b) Portable computer

(c) Computer control systemA computer control system uses a computer to control its output devices according to differentinput signals. Its function is similar to that of an electronic system. Yet a computer control systemcan use high speed calculation to process large volume of input signals within a very short time, andthen generates appropriate outputs with the help of preset programs

. Examples of computer control systems include computer numerical control press brakes, computercontrolled home appliances, computer controlled underground railway systems, etc(a) CNC press brake (b) A proposed computer controlled home appliances

(d) Pneumatic systemA pneumatic system is a system that uses compressed air to transport and control energy. Air isfirst pressurized to give energy in the cylinder. Then signals are input into the system through theuse of switches. Next, air is transferred through sealed pipes to the pneumatic parts for processing.Finally, the force produced by the pneumatic parts is utilized to finish the designated task. The useof pneumatic systems is very extensive, for example, in controlling the movement of train doors, theoperation of automatic production lines and mechanical clamps, etc(a) Production line of CD-ROM

(b) Mechanical clamp(e) Other systemsThere exist many other control systems apart from the ones mentioned above, for example,mail processing systems, commercial operation systems, etc. The input, process and output ofdifferent systems have different properties. In this chapter, we will discuss some of the mostcommon control systems.

2 Sub-systemsA system can be very simple, for example, a switch is only needed in controlling a light bulb towork. However, with the advancement of technology, most of the control systems gradually becomecomplicated that various parts are involved. Take a lift as an example. It needs a number of parts to becooperative in operation, so as to transport passengers to different storeys safely and rapidly (Fig. 6).Fig. 6 (a) A sightseeing lift in a shopping arcade (b) A lift in a hospitalA system may comprise some relatively small parts. They are known as sub-systems. For instance, a liftsystem includes driving system, door opening system, control system, safety system, lighting system,ventilation system and security system

(b) Driving system Fig. 8 Sub-systems in a lift In fact, each sub-system can be considered asan independent system that includes input, process and output. While there exist relationships

between the sub-systems that an output of one sub-system may become the input of another. Take the lift as an example. The output generated from the control system may affect the driving and dooropening systems (Fig. 9). However, attention should be paid in the complexityof relationships of some sub-systems.


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Therefore, when analyzing a complicated control system, that system can be divided into severalcomparatively simple sub-systems so as to familiar with the operation of the whole systemeasily. Besides, based on the sub-system concept, we could understand the relationships of the partsof the whole system much easier.

3 Different types of control systems(a) Open loop and closed loop control systemsThere are basically two types of control system: the open loop system and the closed loop system. They can

both be represented by block diagrams. A block diagram uses blocks to represent

processes, while arrows are used to connect different input, process and output parts.

Explain open loop with block diagram examples

A washing machine is an example of an open loop control system. Fig. 12 shows its blockdiagram. The input and output of an open loop system are unrelated. An example is that theoperation of a washing machine does not depend on the cleanness of the clothes, but rather on the

preset time. Both the structure and the control process of an open loop control system are verysimple, but the result of the output depends on whether the input signal is appropriate or not.Fig. 12 Block diagram of an open loop control system (washing machine)More sophisticated example of an open loop control system is the burglar alarm system (Fig.13). The function of the sensor is to collect data regarding the concerned house. When theelectronic sensor is triggered off (for example, by the entry of an unauthorized person), it will senda signal to the receiver. The receiver will then activate the alarm, which will in turn generate analarm signal. The alarm signal will not cease until the alarm is stopped manually.Fig. 13 Block diagram of an open loop control system (burglar alarm)

18. What are the advantages of closed loop?

closed loop control system compares the output with the expected result or command status, then it takesappropriate control actions to adjust the input signal. Therefore, a closed loop system is alwaysequipped with a sensor, which is used to monitor the output and compare it with the expected result.

The output signal is fed back to the input to produce a new output. A well-designed feedback system canoften increase the accuracy of the output.One advantage of using the closed loop control system is that it is able to adjust its output automatically byfeeding the output signal back to the input. When the load changes, the error signals generated by the systemwill adjust the output. However, closed loop control systems are generally more complicated and thus moreexpensive to make.

1. Accuracy : They are more accurate than open loop system due to their complex construction. Theyare equally accurate and are not disturbed in the presence of non-linearities.

2. Noise reduction ability : Since they are composed of a feedback mechanism, so they clear out theerrors between input and output signals, and hence remain unaffected to the external noise sources.

3. Closed loop control systems are more accurate even in the presence of non-linearities 4. The sensitivity of the system may be made small to make the system more stable 5. The closed loop systems are less affected by noise.

19. How can you design a stable system and Explain different stability criteria.

the stability of a control system is often extremely important and is generally a safety issue in the engineering of asystem. An example to illustrate the importance of stability is the control of a nuclear reactor. An instability of thissystem could result in an unimaginable catastrophe.

The stability of a system relates to its response to inputs or disturbances. A system which remains in aconstant state unless affected by an external action and which returns to a constant state when the external


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action is removed can be considered to be stable.

A systems stability can be defined in terms of its response to external impulse inputs..

A system is stable if its impulse response approaches zero as time approaches infinity..

The system stability can also be defined in terms of bounded (limited) inputs..

A system is stable if every bounded input produces a bounded output.

Control analysis is concerned not only with the stability of a system but also the degree of stability of asystem.. A typical system equation without considering the concept of integral action is of the form.

To know that the system is stable is not generally sufficient for the requirements of control system design.There is a need for stability analysis to determine how close the system is to instability and how muchmargin when disturbances are present and when the gain is adjusted..The objectives of stability analysis is the determination of the following

The degree or extent of system stability The steady state performance

The transient response

The standard method of completing a system analysis includes the following steps..

Determine the equations or transfer functions for each component Create a model - generally a block diagram Formulate the system model by appropriately connecting the blocks nodes and

branches Determine the system characteristics

A number of methods are available for determining the system characteristics including the following.

Root locus method using the s domain plot Frequency Response notes. Using Nyquist diagrams via frequency domain techniques Using Bode Plots via frequency domain techniques

20. Explain Ruthz-Hervitz rule in one sentence.

Ans: n control system theory , the Routh Hurwitz stability criterion is a mathematical test that is a necessary andsufficient condition for the stability of a linear time invariant (LTI) control system . The Routh test is an efficientrecursive algorithm that English mathematician Edward John Routh proposed in 1876 to determine whether all theroots of the characteristic polynomial of a linear system have negative real parts.

21. What are poles and their significance?

The poles and zeros are properties of the transfer function, and therefore of thedifferential equation describing the input-output system dynamics. Together with the
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gain constant K they completely characterize the differential equation, and provide acomplete description of the system.

Ans 2: the transfer function is telling you what kind of an OUTPUT the systemproduces to a given INPUT ...*** Think of POLEs and ZEROs as INFINITY's and ZEROs.*** At ZEROs, the system produces ZERO output ... At POLEs, the systemproduces INFINITE output ... Obviously, you cannot produce infinite voltage withany electronics :) So, it means that, the output will be unbounded (in theory) andSATURATED AT THE HIGHEST POSSIBLE VALUE (in practice).=======================Now, let's talk about a specific case: The TRANSFER FUNCTION can be theIMPEDANCE of a filter, it will be zero (short circuit) at zeros, and INFINITY (opencircuit) at poles ...==============EXAMPLE: Take an inductor and a capacitor, and connect them in parallel. Theirimpedances are Ls and 1/Cs ... So, the parallel inductor and capacitor will have an

impedance of Ls/(1+s^2LC) ... Substitute s=j*2*PI*f. This means that, it has a ZEROat f=0 and a POLE at (2*PI*f)^2=LC (meaning, POLE at f=1/(2*PI*sqrt(LC)).=====================It is clear what the ZERO means. It means that, if f=0 (i.e., NO oscillation activity ispresent or in other words, if you apply a DC voltage to the pins), since the capacitoris open circuit and the inductor is SHORT circuit, inductor will short circuit thecapacitor, and the resulting impedance is ZERO. Since our transfer function is theimpedance, we have ZERO impedance, and, thus, it corresponds to the ZERO ofthe transfer function.=======================The POLE is a little less obvious. Let's assume that, C=1 microfarad, and L=1microhenry. So, C=1E-6, L=1E-6. The POLE of the impedance is at f=159,236 Hz.This means that, if you apply a sine wave of frequency 159 KHz to the pins of theparallel capacitor and resistor, since the impedance is INFINITY at that frequency,the oscillation will be forever sustained and never lost ...==========However, of course, these components will have a little bit of resistance which willmake them non-ideal which will eventually kill the oscillation ...

22. Is there any control system in this room (interview hall)?Not got answer.23. What is Karnaugh map?

The Karnaugh map, also known as the K-map , is a method to simplify boolean algebra expressions. Maurice Karnaugh introduced it in 1953 as a refinement of Edward Veitch 's 1952Veitch diagram . The Karnaugh map reduces the need for extensive calculations by takingadvantage of humans' pattern-recognition capability. It also permits the rapid identification andelimination of potential race conditions .
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The required boolean results are transferred from a truth table onto a two-dimensional grid wherethe cells are ordered in Gray code , and each cell position represents one combination of inputconditions, while each cell value represents the corresponding output value. Optimal groups of 1sor 0s are identified, which represent the terms of a canonical form of the logic in the original truthtable .[1] These terms can be used to write a minimal boolean expression representing the requiredlogic.

Karnaugh maps are used to simplify real-world logic requirements so that they can beimplemented using a minimum number of physical logic gates. A sum-of-products expression c

always be implemented using AND gates feeding into an OR gate , and a product-of-sumsexpression leads to OR gates feeding an AND gate .[2] Karnaugh maps can also be used tosimplify logic expressions in software design. Boolean conditions, as used for example inconditional statements , can get very complicated, which makes the code difficult to read and tomaintain. Once minimised, canonical sum-of-products and product-of-sums expressions can beimplemented directly using AND and OR logic operators .[3]

karnaugh Maps are used for many small design problems. It's true that many larger designsare done using computer implementations of different algorithms. However designs with asmall number of variables occur frequently in interface problems and that makes learning

Karnaugh Maps worthwhile. In addition, if you study Karnaugh Maps you will gain a great deaof insight into digital logic circuits.

24. What are the 4 methods to reduce a Boolean expression?

A Boolean expression is composed of variables and terms . The simplification of Boolean expressions canlead to more effective computer programs, algorithms and circuits. Minimisation can be achieved by anumber of methods, four well known methods are:

1.Algebraic Manipulation of Boolean Expressions

2. Karnaugh Maps

3. Tabular Method of Minimisation

4. Tree reduction

25. Draw 8086 internal architecture.

# Block Diagram:
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Fig: Internal architecture of 8086 Microprocessor

26. What are the different types of buses? In computer architecture , a bus (from the Latin omnibus , meaning "for all") is a communication system thattransfers data between components inside a computer , or between computers. This expression covers all relatedhardware components (wire, optical fiber, etc.) and software, including communication protocols.There are many different types of buses in a computer. There are PCI buses, Monitor buses, cable buses andmemory buses just to name a few of them. Changing the voltage on buses such as a memory bus can be used to helpyou to overclock your memory.The bus connecting the CPU and memory is one of the defining characteristics of the system, and often referred tosimply as the system bus .

It is possible to allow peripherals to communicate with memory in the same fashion, attaching adaptors inthe form of expansion cards directly to the system bus. This is commonly accomplished through some sortof standardized electrical connector, several of these forming the expansion bus or local bus .

As the number of potential peripherals grew, using an expansion card for every peripheral becameincreasingly untenable. This has led to the introduction of bus systems designed specifically to supportmultiple peripherals. Common examples are the SATA ports in modern computers, which allow a numberof hard drives to be connected without the need for a card., the most common example being UniversalSerial Bus . All such examples may be referred to as peripheral buses , although this terminology is notuniversal.

In modern systems the performance difference between the CPU and main memory has grown so great thatincreasing amounts of high-speed memory is built directly into the CPU, known as a cache . In such systemCPUs communicate using high-performance buses that operate at speeds much greater than memory, andcommunicate with memory using protocols similar to those used solely for peripherals in the past. These
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system buses are also used to communicate with most (or all) other peripherals, through adaptors, which inturn talk to other peripherals and controllers. Such systems are architecturally more similar tomulticomputers , communicating over a bus rather than a network. In these cases, expansion buses areentirely separate and no longer share any architecture with their host CPU (and may in fact support manydifferent CPUs, as is the case with PCI ). What would have formerly been a system bus is now often knownas a front-side bus .

Given these changes, the classical terms "system", "expansion" and "peripheral" no longer have the sameconnotations. Other common categorization systems are based on the buses primary role, connecting

devices internally or externally, PCI vs. SCSI for instance. However, many common modern bus systemscan be used for both; SATA and the associated eSATA are one example of a system that would formerly bedescribed as internal, while in certain automotive applications use the primarily external IEEE 1394 in afashion more similar to a system bus. Other examples, like InfiniBand and IC were designed from the startto be used both internally and externally.

Internal bus

The internal bus, also known as internal data bus, memory bus, system bus or Front-Side-Bus, connects allthe internal components of a computer, such as CPU and memory, to the motherboard. Internal data busesare also referred to as a local bus, because they are intended to connect to local devices. This bus is typically

rather quick and is independent of the rest of the computer operations.

External bus

The external bus, or expansion bus , is made up of the electronic pathways that connect the different externaldevices, such as printer etc., to the computer.

27. What are the different registers in CPU?

Ans : Registers are normally measured by the number of bits they can hold, for example, an "8-bit registeror a "32-bit register". A processor often contains several kinds of registers, that can be classified accordinglyto their content or instructions that operate on them:

User-accessible registers instructions that can be read or written by machine instructions. Themost common division of user-accessible registers is into data registers and address registers.

o Data registers can hold numeric values such as integer and, in some architectures, floating- point values, as well as characters , small bit arrays and other data. In some older and low endCPUs, a special data register, known as the accumulator , is used implicitly for manyoperations.

o Address registers hold addresses and are used by instructions that indirectly access prima

memory . Some processors contain registers that may only be used to hold an address or only to

hold numeric values (in some cases used as an index register whose value is added aan offset from some address); others allow registers to hold either kind of quantity. Awide variety of possible addressing modes , used to specify the effective address of anoperand, exist.

The stack pointer is used to manage the run-time stack . Rarely, other data stacks aaddressed by dedicated address registers, see stack machine .

o General purpose registers (GPR s) can store both data and addresses, i.e., they arecombined Data/Address registers and rarely the register file is unified to include floating

point as well.
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o Conditional registers hold truth values often used to determine whether some instructionshould or should not be executed.

o Floating point registers (FPR s) store floating point numbers in many architectures.o Constant registers hold read-only values such as zero, one, or pi . o Vector registers hold data for vector processing done by SIMD instructions (Single

Instruction, Multiple Data).o Special purpose registers (SPR s) hold program state; they usually include the program

counter , also called the instruction pointer, and the status register ; the program counter andstatus register might be combined in a program status word (PSW) register. The

aforementioned stack pointer is sometimes also included in this group. Embeddedmicroprocessors can also have registers corresponding to specialized hardware elements.o In some architectures, model-specific registers (also called machine-specific registers ) st

data and settings related to the processor itself. Because their meanings are attached to thedesign of a specific processor, they cannot be expected to remain standard between processorgenerations.

o Memory Type Range Registers (MTRR) Internal registers registers not accessible by instructions, used internally for processor operations.

o Instruction register , holding the instruction currently being executed.o Registers related to fetching information from RAM , a collection of storage registers located

on separate chips from the CPU:

Memory buffer register (MBR) Memory data register (MDR) Memory address register (MAR)

Hardware registers are similar, but occur outside CPUs.

28. What is the use of segment register?

Ans 1.In the x86 processor architecture, memory addresses are specified in two parts called the segmentand the offset. One usually thinks of the segment as specifying the beginning of a block of memoryallocated by the system and the offset as an index into it. Segment values are stored in the segmentregisters. There are four or more segment registers: CS contains the segment of the current instruction (IPis the offset), SS contains the stack segment (SP is the offset), DS is the segment used by default for mostdata operations, ES (and, in more recent processors, FS and GS) is an extra segment register. Mostmemory operations accept a segment override prefix that allows use of a segment register other than thedefault one.

Ans 2: basically registers are used to store data and address. for specifying the base address i.e startingblock of memory ,segment registers are used . it gives only the starting adress of any segment .one thing isimportant in the case of 8086 architechture is that ,for producing physical address ,the segment registeraddress must be rotate bit-wise 4 times left and 0000 must be embedded. now offset address is added inthe modify content of segment register to get the required memory location.

29.Which is the 1st 32-bit microprocessor? (not getting the answer)

Ans: the first 32 bit intel micro processor was Intel 386 processor, released in October 1985

Ans 2: The first true 32-bit processor was the Intel 80386.

30. What are the different UPS?

UPS types A variety of design approaches are used to implement UPS systems, each with distinct performance characteristics.The most common design approaches are as follows:
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1. Standby : The Standby UPS is the most common type used for Personal Computers. the transfer switch isset to choose the filtered AC input as the primary power source (solid line path), and switches to the battery/ inverter as the backup source should the primary source fail. When that happens, the transfer switch mustoperate to switch the load over to the battery / inverter backup power source (dashed path). The inverteronly starts when the power fails, hence the name "Standby."2. Line Interactive : is the most common design used for small business, Web, and departmental servers. Inthis design, the battery-to-AC power converter (inverter) is always connected to the output of the UPS.Operating the inverter in reverse during times when the input AC power is normal provides batterycharging. When the input power fails, the transfer switch opens and the power flows from the battery to the

UPS output. With the inverter always on and connected to the output, this design provides additionalfiltering and yields reduced switching transients when compared with the Standby UPS topology. Inaddition, the Line Interactive design usually incorporates a tap-changing transformer. This adds voltageregulation by adjusting transformer taps as the input voltage varies. Voltage regulation is an importantfeature when low voltage conditions exist, otherwise the UPS would transfer to battery and then eventuallydown the load. This more frequent battery usage can cause premature battery failure. However, the invertercan also be designed such that its failure will still permit power flow from the AC input to the output, whicheliminates the potential of single point failure and effectively provides for two independent power paths.This topology is inherently very efficient which leads to high reliability while at the same time providingsuperior power protection.

3 Standby on-line hybrid : The Standby On-Line Hybrid is the topology used for many of the UPS under 10kVA whichare labeled "online." The standby DC to DC converter from the battery is switched on when an AC power failure isdetected, just like in a standby UPS. The battery charger is also small, as in the standby UPS. Due to capacitors in theDC combiner, the UPS will exhibit no transfer time during an AC power failure. This design is sometimes fitted withan additional transfer switch for bypass during a malfunction or overload. Figure 3 illustrates this topology.4. Standby-Ferro The Standby-Ferro UPS was once the dominant form of UPS in the 3-15kVA range. This designdepends on a special saturating transformer that has three windings (power connections). The primary power pathis from AC input, through a transfer switch, through the transformer, and to the output. In the case of a powerfailure, the transfer switch is opened, and the inverter picks up the output load.

5. Double Conversion On-Line This is the most common type of UPS above 10kVA. The block diagram of the DoubleConversion On-Line UPS, illustrated in Figure 5, is the same as the Standby, except that the primary power path isthe inverter instead of the AC main. In the Double Conversion On-Line design, failure of the input AC does not causeactivation of the transfer switch, because the input AC is NOT the primary source, but is rather the backup source.Therefore, during an input AC power failure, on-line operation results in no transfer time. The on-line mode ofoperation exhibits a transfer time when the power from the primary battery charger / battery / inverter power pathfails. This can occur when any of the blocks in this power path fail. The inverter power can also drop out briefly,causing a transfer, if the inverter is subjected to sudden load changes or internal control problems.

6. Delta Conversion On-Line This UPS design is a new technology introduced to eliminate the drawbacks of theDouble Conversion On-Line design and is available in the range of 5kVA to 1 MW. Similar to the Double Conversion

On-Line design, the Delta Conversion On-Line UPS always has the inverter supplying the load voltage. However, theadditional Delta Converter also contributes power to the inverter output. Under conditions of AC failure ordisturbances, this design exhibits behavior identical to the Double Conversion On-Line.

31. Compare 8086 and 80286

The 8086/8088 is a 16 bit processor running on a 16 bit (8086) or 8 bit (8088) bus with a 20 bit address. It canaddress 1 MB of memory. Addressing consists of adding the program's effective address to the (left shifted by 4)value of one of the segment registers. Think of segments as multiple 64kb regions of memory, overlapping at adistance of 16 bytes. The 80286 is a 16 bit processor running on a 16 bit bus with a 24 bit address. It can address16mb of memory.


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In real mode, it operates the same as an 8086. This is the power on reset state. In protected mode, the segmentregister changes meaning. Instead of a segment address (left shifted by 4 base address), the segment register is anindex into a page descriptor table, which is a table that supports virtual mode. Each element in the page descriptortable also contains information about the protection status of that page, so that page protection can be provided.Unfortunately, since the meaning of the segment register changed, the 80286 was not object code compatible withprograms written for the 8086/8088. This is one of the factors that made the 80286 unpopular.

Sent up to here

1. Explain the internal architecture of 8086

8086 CPU ARCHITECTURE

The microprocessors functions as the CPU in the stored program model of the digital computer. Its job is togenerate all system timing signals and synchronize the transfer of data between memory, I/O, and itself. Itaccomplishes this task via the three-bus system architecture previously discussed.

The microprocessor also has a S/W function. It must recognize, decode, and execute program instructionsfetched from the memory unit. This requires an Arithmetic-Logic Unit (ALU) within the CPU to perform

arithmetic and logical (AND, OR, NOT, compare, etc) functions.

The 8086 CPU is organized as two separate processors, called the Bus Interface Unit (BIU) and the ExecutionUnit (EU). The BIU provides H/W functions, including generation of the memory and I/O addresses for thetransfer of data between the outside world -outside the CPU, that is- and the EU.

The EU receives program instruction codes and data from the BIU, executes these instructions, and store theresults in the general registers. By passing the data back to the BIU, data can also be stored in a memorylocation or written to an output device. Note that the EU has no connection to the system buses. It receivesand outputs all its data thru the BIU.


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The only difference between an 8088 microprocessor and an 8086 microprocessor is the BIU. In the 8088, theBIU data bus path is 8 bits wide versus the 8086's 16-bit data bus. Another difference is that the 8088instruction queue is four bytes long instead of six.

The important point to note, however, is that because the EU is the same for each processor, the programminginstructions are exactly the same for each. Programs written for the 8086 can be run on the 8088 without anychanges.

Ans 2:

The Intel 8086 is a 16- bit microprocessor intended to be used as the CPU in a microcomputer. The term 16 -bitmeans that its arithmetic logic unit, internal registers, and most of its instructions are designed to work 16-bit binwords . It has 16-bit data bus and 20-bit address bus.

Words will be stored in two consecutive memory locations. If the first byte of a word is at an even address, the 8086can read the entire word in one operation. If the first byte of the word is at an odd address, the 8086 will read thefirst byte in one operation, and the second byte in another operation.

Following figure shows the internal block diagram of 8086 microprocessor.

The 8086 CPU is divided into two independent functional parts, the bus interface unit or BIU, and the execution un

or EU.

Fig. 8086 internal block diagram.

BIU (Bus Interface Unit):- It sends out tasks.
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Control engineering has an important role in several major emerging technologies: next generation smartmanufacturing systems, smart grid technologies, engine management systems for energy efficiency, hybrid vehiclecontrol, autonomous systems and production of high valued added pharmaceuticals. This area plays an importantrole in societal challenges such as energy (wind turbines) and healthcare (e.g. prosthetics control systems,automated drug administration), and its importance is likely to increase with transition to leaner, intensivesustainable technologies. The area is undergoing resurgence due to a need for more sophisticated control for morecomplex technologies; it has transformative potential, for example in smart manufacturing and process systems. Anumber of "grand challenges" for control have been identified in The Impact of Control Technology (The Impact oControl Technology, T. Samad and A.M. Annaswamy (eds.), IEEE Control Systems Society, 2011) and the PositionPaper on Systems and Control in FP8 (PDF 2MB) (HYCON2, Oct 2011).

4. Draw the block diagram of a control system and write its transfer function

Ans:

block diagrams are ways of representing relationships between signals in a system. Here is ablock diagram of a typical control system. Each block in the block diagram establishs arelationship between signals.

4. What is ROC?

Not got answer

6. Transformation between S and Z plane.

Ans: There are a number of different mappings that can be used to convert a system from the complex Laplacedomain into the Z-Domain. None of these mappings are perfect, and every mapping requires a specific startingcondition, and focuses on a specific aspect to reproduce faithfully. One such mapping is the bilinear transformwhich, along with prewarping, can faithfully map the various regions in the s-plane into the correspondingregions in the z-plane.

7. What is wave studio?8. What is bit rate?9. In telecommunications and computing , bit rate is the number of bits that are conveyed or processed

per unit of time. The bit rate is quantified using the bits per second (bit/s or bps ) unit, often inconjunction with an SI prefix such as kilo- (kbit/s or kbps), mega- (Mbit/s or Mbps), giga- (Gbit/sGbps) or tera- (Tbit/s or Tbps).It describes the rate at which bits are transferred from one location toanother. In other words, it measures how much data is transmitted in a given amount of time.

10. What is the difference between mp3 and wave formats

Ans: There are two types of file formats. Lossy, and on-Lossy. In the case of audio, MP3 is a lossy onebecause it compresses the audio. Though this is intended to save filespace, it does this by weeding out theunneccessary data. In doing this , the quality of the audio can suffer some, but not enough so that you'd beable to tell the difference.
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