Digital Electronics Quiz 1 :

Topic : Number Representation

Basic system parameters:

System parameters are classified as:

• Static | Dynamic
• Causal | Non-Causal
• Time invariant | Varient
• Linear | Non-Linear
• Stable | Unstable
• Invertible | Non-Invertible

1.Static and Dynamic system:

Static system: If output of system depends on only present values of input then system is called static system. These systems are also known as system without memory.

Example: y(t)= sin[x(t)] , y(t)= x(t)

Dynamic system: If output of a system depends on past or future values of input at any instant of time is called dynamic system.

Example: y(t)= x(t+1) , y(t)= x(2t) , y(t)= x(t^2) , y(t)= x[sgn(t)] , y(t)= x[u(t)]

Note:

• If any operator (square, cube,..... addition,.......square root,...... sin, cos,....,u(t),..., sgn(t),..... hyperbolic, exponential, modulus etc.) operates on time either in x(t) or y(t) than it is the case of Time scalling and system become Dynamic System.
• For static system there should not be any shifting or scalling in time either in x(t) or y(t).
• All integral and derivatives system are Dynamic system.

2.Causal | Non-Causal System:

Causal System: If Output of System does not depends on future value of input at any instant of time the system is called causal system.

Example: y(t)= x(t), y(t)= x(t) + x(t-1) , y(t)= 2tx(t) etc.

Non- Casual System: If output of system depends on future values of input at any instant of time system is called Non-Causal.

Example: y(t)= x(t+1), y(t)= x(t) + x(t+1) etc.

Anti-Causal System: If output of system depends on only future value of input than system is called Anti-Causal System. Anti-Causal System is a subset of Non-Causal system .

Example: y(t)= x(t+1)

Note: 

• If any operator operates on time either in x(t) or y(t)  than system is non causal.

3.Linear | Non-Linear System:

Linear system follow law of of superposition. Law of superposition is necessary and sufficient condition to prove the linearity of the system.

Law of superposition is equal to the sum of Law of Additivity and Law of Homogeneity. The system which does not follow law of superposition is said to be nonlinear system.

Law of Homogeneity:

Let us consider a system  y(t)=  x(t)

Let us consider another example y(t)=  x²(t)

So it does not follow Homogeneity so the system is Non-Linear system.

Law of Additivity

Examples:

1. y(t)= sin[x(t)] ….................. Non-Linear
2. y(t)=|t|.x(t) ………………… Linear
3. y(t)= sint.x(t) ……………... Linear
4. y(t)= |x(t)| ………………….Non Linear
5. y(t) = x(t) + 10 ……………. Non-Linear

Note:

• If any operator operates on x(t) or y(t) the system will be non linear.
• Linearity is  independent of coefficient.
• For linear system output should be zero for zero input.
• Zero input and zero output condition is necessary for linear system but not the sufficient condition.
• Conjugate operator is a non linear operator.

4.Time invariant | Variant System:

A system is said to be time invariant if any amount of delay provided in input must be reflected in output. Otherwise system will be time variant.

Note:

• If any operator operates and time either in x(t) or y(t) then the system will be time variant.

Example: y(t)= x[cost), y(t)= x[tan(e^t)], y(t)= x[logt]

• If coefficient in system relationship is a function of time then system will be time variant system.

y(t)=t.x(t)

• All split systems are time variant system.

y(t)= { x(t)       , t<0

           x(t+1)   , t>0 }

5.Stable | Unstable System:

Bounded input Bounded output criteria:

For stable system output should be bounded and finite for or finite or bounded input at all instant of time.

Eg: y(t)= 2x(t) ……….…..Stable

      y(t)= t.x(t) …………… Unstable

6.Invertible and Non-Invertible System:

For an  invertible system there should be an one to one mapping between input and output for all the instant of time.

Note:

When an inverter power system is cascaded with its inverse system than the  output of its composite system will be equal to input.

Example:

y(t)= x²(t) .................... Non Invertible

y(t)= dx(t)/dt ............... Non Invertible

 

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The Boundary Conditions on the electric and magnetic fields (i.e. relationships between the electric and magnetic fields on either side of a boundary) are important for understanding the behaviour of electromagnetic fields, We can drive these Boundary Condition from Maxwell’s equations. For Electric field Intensity: If the field in one region of dielectric medium ε1 is known then the field in adjacent region can be calculated using Boundary Condition. 

Case_1: Electric Field is Normal to the Boundary

                                   

                                       We Know that,

                            i.e for Normal Density,          D_n2 = D_n

For region having Charge on Boundary, 

Note:

1. Considered surface spread in both the region that’s why we apply single Gauss law Equation for analysis. If Boundary has a surface charge   than normal component of Density will be:
   
   
   
2. The Normal Component of flux density is continuous on both the side when there is no surface charge else discontinuous by an amount equal to surface charge density  .

 

Case_2: When Electric field is parallel to Boundary

            We know that,

• Tangential Component of Electric Field Intensity is Always Continuous.

• The Formula of Boundary Condition for both Electric and Magnetic Field is Summarized in the table.

   

Control System: A control system is an arrangement of physical components connected or related in such a manner as to command, direct, or regulate itself or another system.

v A control system is that means by which any quantity or interest is maintain according to desired manner.

vIn a Control System analysis we are not think about what is inside the system we only think what behaviors of system is.

vThe events or group of elements are called plants and the one who control the plants is called Controller. Controller performs two jobs.

1.      Error Detection

2.      Control Action

v    vWhen feedback is present than controller performs Error Detection + Control Action

v    vWhen feedback is not present than only Control action is performed.

Input: The input is the stimulus, excitation or command applied to a control system, typically from an external energy source usually in order to produce a specified response from a control system. It is nothing but a desired output.

Output: The output is the actual response obtained from a control system. It may or may not be equal to the specified response implied by the input.

System:  A system is an arrangement of physical components connected or related in such a way as to form an entire unit. System means of transfer of (one form of energy to other)or exchange of signal.

Example of Control system:

1.           An Electric switch in which flipping the switch ON and OFF may be considered as the input and Output is the flow or nonflow of electricity.

2.           A thermostatically controlled heater where input to the system is reference temperature and output is the actual temperature.

3.           Automatic Washing machines in which the amounts of detergent, bleach, water, temperature of the water and time for wash and spin cycle are considered as input whereas the percentage of cleanliness is the output.

There are two types of control system: Open-loop and Closed-loop systems

Open- loop Control System: An open loop control system is one in which the control action is independent of the output. In other word these are the systems in which present output depends upon present input only.

In such system there is absence of error detecting elements.

Some important features of open-loop control system are:

1.         The ability to perform accurately is determined by their calibration. To calibrate means to establish the input - output relation to obtain desired system accuracy.

2.      They are not usually troubled with problems of instability.

3.       Simple to design and cheaper.

Example of Open - loop Control system: Fan, Torch, Traffic System, Most automated toasters, Washing machine coffee server, 

Close – loop control system: The close-loop control systems are more commonly also known as feedback control system. These are the systems in which present output depends on present input as well as previous output.

Feedback: The Feedback is that property of a closed-loop system which permits the output to be compared with the input to the system so that the appropriate control action may be formed as some function of the output and input.

More general, feedback is said to exist in a system when a closed sequence of cause-and-effect relations exists between system variables.

Characteristics of FEEDBACK:

1.      Increased Accuracy.

2.      Tendency towards oscillation or instability.

3.       Reduced sensitivity.

4.       Reduced effects of nonlinearities.

5.       Reduced effects of external disturbances or noise.

6.       Reduced Bandwidth.                                                                                        

Some important features of close-loop control system are:

1. Accurate and Reliable

2. Output is less affected by Noise

3. The Effect of Non linearity is less

4. The Effect of parameter variation is less

5. Complex to design and costly

6. There is problem of stability

2

Example of closed - loop Control system: An autopilot mechanism and the airplane it controls, Controlled AC, Microwave, Any commanding or sensing system, Human Reciprocity  System, Smoking, Human driving system, walking in Room

 Hello Friends , I am uploading Practice question set of 50 Question for Electronics and electrical branch .

These questions are also important for PSU exams and interview. All questions are concept based question 

To download the Question :IES_EE PRACTICE QUESTION SET-1

To download answer key:Answer Key

 

The GATE 2021 is organized by IIT Bombay . The Indian Institute of Technology, Bombay on 7th August 2020 released the information brochure for Graduate Aptitude Test in Engineering (GATE) 2021 on its official website.

After analyzing Brochure , it is observed that some changes are done in exam pattern , exam city and also in syllabus .

Changes in exam pattern:

In GATE 2021, the candidates will also have to answer 3 types of questions

1. Multiple Choice Questions (MCQs)

2. Numerical Answer Type Questions (NATs)

3.Multiple Select Questions (MSQ): In this type of question more than one option may                                                                             correct among the given four options.

The division of marks among the sections has also changed as given below:

1. Engineering Mathematics - 13 Marks

2. Subject Questions - 72 Marks

3. General Aptitude - 15 Marks

 

•  Four more cities Jhansi (IIT Kanpur), Dhenkanal (IIT Kharagpur), Chandrapur (IIT Bombay) and Muzzaffarnagar (IIT Roorkee) are added as exam city for GATE 2021 On the other hand, Pala (IIT Madras) has been removed from the list. There are a total of 195 Indian exam cities and 5 abroad. However, there are chances of international cities being dropped due to COVID-19 pandemic.
• GATE 2021 will be held from February 5 to 7 and 12 to 14 as a computer based test.
• Registrations for GATE 2021 will start from September 14, 2020.

As per new rule any candidate may appear in  more than one paper.

• EC candidate may appear in IN / PH paper
• EE candidate may appear in IN  paper
• IN candidate may appear in EC/EE/PH  paper

GATE 2021 Official Website : https://www.gate.iitb.ac.in/

To Download GATE 2021 Official Brochure Click Here :

GATE 2021 Official Brochure

To Download Syllabus Click on below link.

1. Electronics Engineering

2. Electrical Engineering

3. Electonics and Instrumentation

4. Mechanical Engineering

After Comparing Syllabus with previous year syllabus following changes are observed.

Changes Analysis for EC Paper:

1. Numerical Methods, Correlation and Regression Analysis is Removed From Engineering          Math.

2. FFT, Cascade and parallel structure realization and Digital Filter design Techniques is              removed from signal and system.

3. IC Technology is removed from EDC.

4. Timer 555, Power Amplifier, sinusoidal oscillator removed from ADC.

5. PLAs, PLDs and 8085 are removed and Computer system architecture added in Digital              electronics.

6. FDM, CDMA, TDMA removed and CRC code added in Communication

7. Electrostatics is removed and Circular waveguide is added in EMT

8. No other major changes are found. 

Changes Analysis for EE Paper: 

1. Numerical Methods and Transform Theory are removed from Engineering math.

2. Graph Theory is removed from Electric circuit.

3. RMS and Avg value calculation for periodic waveform is added in signal and system

4. 8085 is removed 

5. No other major changes are found.

Changes Analysis for IN Paper: 

1. EMT and Machines added.

2. Source and effect of noise and interference in electronics added in Analog circuit.

3. Mass spectrometer and Spectro photometer added in communication and optical

4. No other major changes are found.