Basics of Operational Amplifier (EEE Department @ LAQSHYA College)

Basics of Operational Amplifier

Operational amplifier is so named as it is used to perform mathematical operations such as addition, subtraction, multiplication, differentiation, integration and many more. As op-amp has wide range of applications, some of its various applications are in industrial, communication, computer, control, and medical applications in additional with them in military applications too.

            An integrated circuit manufacturing industries incorporates integrated transistors, diodes, resistors and capacitors within op-amp ICs. So it is an extremely versatile device which has countless applications in many more areas.

            Since the op-amp is an integrated device, we don’t find any discrete components like active components such as transistors and diodes and passive components like R, L & C. consequently, it offers small size, low cost, high reliability, more temperature stability and low power consumption.

Block Diagram of A typical Op-Amplifier:

1à Non inverting input terminal

2à Inverting input terminal

3àDual input balanced output differential amplifier

4à Dual input unbalanced output differential amplifier

5à Emitter follower with constant current source. It is used to shift the DC level to ground in order to keep Q-point stable and also to limits the output voltage swing.

6à Complementary symmetry push-pull amplifier.

Schematic Symbol of an Op-Amplifier

Five basic terminals of op-amp :

                                Pin2àNon inverting terminal

                                Pin3à Inverting terminal

                               Pin7&pin4à Power supplies

                                Pin6à Output terminal

Equivalent Circuit of an Op-Amplifier:

V_dà Differential input voltage

R_inà Input resistance of an op-amp

R_outà Output resistance of an op-amp

A_vd & R_outà  Thevenin’s voltage source and Thevenin’s resistance respectively looking back into the output terminals of an op-amp

Note: An electrical equivalent circuit is used to analyze basic operating principles of op-amp and in observing the effects of feedback.

Ideal Op-Amp Characteristics :
  _a) R_i=∞     
   b) R_o=0 

              c) A_0L=∞         

  d) BW=∞       

  e) Zero offset voltages           

  f) CMRR=∞

R_i=∞:

     Since input resistance is infinite, Ib1&Ib2 bias currents are ideally zero and practically very small. Due to R_i is very large loading effect is avoided.

R₀=0:

     Since output resistance is zero the voltage across output terminals is independent of current flowing through the load. If R_o=0 , it is used to drive infinite number of sources.

A_0L=∞:

     It implies there is a finite amount of output voltage for the zero differential input voltages.

BW=∞:

     It shows, op-amp is used for both DC&AC where the frequency ranges from 0 HZ to high frequency.

Zero offset :

     It means for V₁=V₂=0 the V_o  must be zero.

CMRR(Common Mode Rejection Ratio):

     For an ideal op-amp,                                  CMRR=ρ=A_{d /} A_c=∞  

      A_dàdifferential mode gain                        A_càcommon mode gain

DC Characteristics of Op-Amp:

a)      V_ios: The spurious i/p voltage causes to get small mv of output even in the presence of both the inputs are grounded. For an ideal op=amp it should be zero.

b)     I_ios:  The algebraic difference between the two bias currents is called input offset currents.

                        I_ios=|I_b1-I_b2|

c)      I/P Bias Current: The average sum of two bias currents flowing into an op-amp for the two bases of the transistors is called as input bias current.

                                      I_b=(I_b1+I_b2)/2

d)     Thermal Drift: The effect of variation in temperature causes changes in V_ios, I_ios & I_b is referred as thermal drift.

AC Characteristics :

a)      Gain Bandwidth Product: The range of operating frequencies of an op-amp at its unity gain is called gain bandwidth product. It also describes frequency response where variation in magnitude and phase of the gain due to change in frequency.

b)     Slew Rate: The maximum rate of change of output voltage is known as slew Rate.

SR=dVo/dt  | _max

                 SR= dVo/dt | _max=I_max/C

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Article By

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Mr.K.Pithamber                

Assistant Professor

CSE Department

LAQSHYA Institute of Technology & Sciences              

Scales in Engineering Drawing (Mechanical Department @ LAQSHYA College)

Engineering Drawing - Scales

Dimensions of large objects must be reduced to accommodate on standard size drawing sheet. This reduction creates a scale of that reduction ratio, which is generally a fraction. Such a scale is called reducing scale and that ratio is called representative factor.

Similarly in case of tiny objects dimensions must be increased for above purpose. Hence this scale is called enlarging scale.

Here the ratio called representative factor is more than unity.

Representative factor (r.f.) =   Dimension of drawing / Dimension of object

Length of scale =     r.f.  * max. Length to be measured.

Types of scales:

1. Plain scales                 ( for dimensions up to single decimal)
2. Diagonal scales           ( for dimensions up to two decimals)
3. Vernier scales             ( for dimensions up to two decimals)
4. Comparative scales     ( for comparing two different units)
5. Scale of cords              ( for measuring/constructing angles)

Plain scale

Plain scale: - This type of scale represents two units or a unit and its sub-division.

Problem:-  Draw a scale 1 cm = 1m to read decimeters, to measure maximum distance of 6 m. Show on it a distance of 4 m and 6 dm.

Construction:-

Calculate r.f. = Dimension of drawing / Dimension of object

                                   r.f. = 1cm/ 1m = 1/100

 length of scale =   r.f. x max. Distance

                       = 1/100 x 600 cm

                                  = 6 cms

B) Draw a line 6 cm long and divide it in 6 equal parts. Each part will represent larger division unit.

C) Sub divides the first part which will represent second unit or fraction of first unit.

D) Place (0) at the end of first unit. Number the units on right side of zero and subdivisions. On left-hand side of zero. Take height of scale 5 to 10 mm for getting a look of scale.

E) After construction of scale mention its rf and name of scale as shown.

 f) Show the distance 4 m 6 dm on it as shown.

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Article By

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N.Nagendra Kumar                  

Assistant Professor

Mechanical Department

LAQSHYA Institute of Technology & Sciences              

The Role of Computer Forensics in Cyber Crime (CSE Department @ LAQSHYA College)

The Role of Computer Forensics in Cyber Crime

The world has been transforming into cyber from the last two decades. Cyber is a form of electronic communication networks and virtual reality. As our lives become more wireless and everything takes an online form, computer and networks are becoming the most powerful interfaces. This transformation has raised many new disciplines like cyber forensics, computer forensics, network forensics, cellular forensics and many more.

What is Cyber Crime?

Cyber crime refers to any crime that is committed using computers or the internet. Cyber crime includes hacking, cracking, copyright infringement, pornography, spam mails, phishing, internet fraud, identity theft, introducing viruses, malwares etc.

What is Forensics?

Forensics is a scientific technique to process the evidence that is admissible in the court. The word forensic means “to bring the court”.

What is Cyber Forensics?

Cyber forensics is the identification, collection, preservation and analysis of evidence extracted from various elements of computer media, other computer peripherals, and computer networks. Cyber forensics is a composition of computer forensics and network forensics.

Cyber Forensic is of two types
1) Computer Forensics
2) Network Forensics 

Computer forensics & its role in cyber crime:

Computer forensics focuses on gathering digital evidence from computer or any other digital media after a crime has occurred. Computer forensics carries on a methodological investment to find out the incidents occurring with the digital media & responsible parties for those actions.

In a cyber crime, the computer could be used to either commit the crime or it could have been the target of the crime(victim). The main goal of computer forensics is to gather evidence in cyber crimes. Many computer forensic tools are available to discover, analyze & preserve the digital evidence.  

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Article By

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CSE Department               

LAQSHYA Institute of Technology & Sciences              

Crystallography (H & S Department @ LAQSHYA )

Crystallography 

A crystal is a solid object with a geometric shape that reflects a “long-range” regular internal structure.

Space lattice: The regular internal structure of a crystal is manifested by the existence of a space lattice, which is "an array of points in space that can be repeated indefinitely".

Unit cell: A unit cell is the smallest number of "points" which completely define the space lattice. The repetition of those points or unit cells in a space lattice is performed by certain operations which build the space lattice.

The selection of unit cells:

Ø  The smallest sized unit that retains the characteristics of the space lattice.

Ø  Edges of the cell should coincide with symmetry axes.

Ø  Edges of the cell related to each other by the symmetry of the lattice.

The Crystal Systems

The crystal classes are grouped into seven crystal systems based on the following criteria:

            1) Relative lengths of the crystallographic axes

            2) Number of crystallographic axes

            3) Values of the inter-axial angles

            4) Some essential element of symmetry

The seven crystal systems are:

(1) The Cubic system: Three crystallographic axes, a = b = c, = = = 90. Essential element of symmetry is a three-fold rotary or rotary inversion axis.

(2) The Tetragonal system: Three crystallographic axes, a = b c, = = = 90. Essential element of symmetry is a four-fold rotary or rotary inversion axis.

(3) The Rhombohedral system: Four crystallographic axes, three of which are equal and coplanar and at angles of 120°, fourth axis "c" is perpendicular to the other three axes, and is characterized by commonly being a three fold axis of symmetry.

(4) The Hexagonal system: Four crystallographic axes, three of which are equal and coplanar (a₁, a₂, a₃) and at angles of 120°, fourth axis (c) is perpendicular to the other three axes, and is characterized by being a six fold axis of symmetry.

(5) The Orthorhombic system: a b c, = = = 90. Essential element of symmetry is a two-fold rotary axis.

(6) The Monoclinic system: a b c, = = 90, > 90. Essential element of symmetry is a two fold rotary axis or a plane. The 2-fold rotational axis or the direction perpendicular to the mirror plane is usually taken as the b axis, the a axis is inclined to the front (b > 90°), and c is vertical.

(7) The Triclinic system: a b c, . No essential element of symmetry. Additional criteria: As much as possible, b and a should be both > 90°. The most pronounced zone should be vertical.

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Article By

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Mr.Ibhrahim                   

Assistant Professor

H&S Department

LAQSHYA Institute of Technology & Sciences              

Introduction To Web Services (CSE Department @ LAQSHYA College)

Introduction To Web Services

A web service is a collection of open protocols and standards used for exchanging data between applications or systems. Software applications written in various programming languages and running on various platforms can use web services to exchange data over computer networks like the Internet in a manner similar to inter-process communication on a single computer. This interoperability (e.g., between Java and Python, or Windows and Linux applications) is due to the use of open standards.

Web services are XML-based information exchange systems that use the Internet for direct application-to-application interaction. These systems can include programs, objects, messages, or documents.
Interoperability has Highest Priority

“Any thing that is accessible irrespective of programming language and platform.”

Components of Web Services

The basic Web services platform is XML + HTTP. All the standard Web Services works using following

components

1.       SOAP (Simple Object Access Protocol)

2.       UDDI (Universal Description, Discovery and Integration)

3.       WSDL (Web Services Description Language)

1. SOAP

S SOAP provides a way to communicate between applications running on different operating systems, with different technologies and programming languages.

Skeleton SOAP Message

<?xml version="1.0"?>
<soap:Envelope
xmlns:soap="http://www.w3.org/2001/12/soap-envelope"
soap:encodingStyle="http://www.w3.org/2001/12/soap-encoding">
<soap:Header>
...

</soap:Header>
<soap:Body>
...
  <soap:Fault>
  ...
  </soap:Fault>
</soap:Body>

2. UDDI:

 Universal Description, Discovery and Integration (UDDI) is a directory service where businesses can register and search for Web services. It can store all the WSDL documents in it. Provider will publishes the WSDL documents to the UDDI registry and consumers will browse for a WSDL document form the registry.

WSDL

3.   WSDL

Stands for Web Services Description Language

WSDL is often used in combination with SOAP and XML Schema to provide web services over the Internet.

The main structure of a WSDL document looks like this:

<definitions> … It defines the name of the web service. <types>    definition of types........ the data types that are used by the web service. </types> <message>    definition of a message.... data elements of an operation. </message> <portType> It describes a web service, the operations that can be performed, and the messages that are involved.       <operation>                   definition of a operation.......        </operation> </portType> <binding>    definition of a binding.... data format and protocol for each port type. </binding> <service>    definition of a service....</service></definitions> --------------------------------------------------------------------------------- Article By -------------- R.Rupa                      Assistant Professor CSE Department LAQSHYA Institute of Technology & Sciences

Fluids & Types of Fluid Flow's (Mechanical Department @ LAQSHYA)

Fluids & Types of Fluid Flow's

The Fluid Flow is classified as,steady and unsteady, compressible and in compressible, viscous and nonviscous, and rotational and irrotational. Some of these characteristics reflect properties of the liquid itself, and others focus on how the fluid is moving.

Fluid evenness: Steady and unsteady flow:
 Fluid flow can be steady or unsteady, depending on the fluid’s velocity:
• Steady: In steady fluid flow, the velocity of the fluid is constant at any point.
• Unsteady: When the flow is unsteady, the fluid’s velocity can differ between any two points.
For example, suppose you’re sitting by the side of a stream and note that the water flow is not steady: You see eddies and backwash and all kinds of swirling. Imagine velocity vectors for a hundred points in the water, and you get a good picture of unsteady flow — the velocity vectors can be pointing all over the map, although the velocity vectors generally follow the stream’s overall average flow.

Fluid squeezability: Compressible and in compressible flow:
Fluid flow can be compressible or in compressible, depending on whether you can easily compress the fluid. Liquids are usually nearly impossible to compress, whereas gases (also considered a fluid) are very compressible.
A hydraulic system works only because liquids are in compressible — that is, when you increase the pressure in one location in the hydraulic system, the pressure increases to match everywhere in the whole system. Gases, on the other hand, are very compressible — even when your bike tire is stretched to its limit, you can still pump more air into it by pushing down on the plunger and squeezing it in.

Fluid spinning: Rotational and irrotational flow:

Fluid flow can be rotational or irrotational. If, as you travel in a closed loop, you add up all the components of the fluid velocity vectors along your path and the end result is not zero, then the flow is rotational.
To test whether a flow has a rotational component, you can put a small object in the flow and let the flow carry it. If the small object spins, the flow is rotational; if the object doesn't spin, the flow is irrotational.
Fluid thickness: Viscous and non viscous flow:
Liquid flow can be viscous or non viscous. Viscosity is a measure of the thickness of a fluid, and very gloppy fluids such as motor oil or engine oil are called viscous fluids.
Viscosity is actually a measure of friction in the fluid. When a fluid flows, the layers of fluid rub against one another, and in very viscous fluids, the friction is so great that the layers of flow pull against one other and hamper that flow.
Viscosity usually varies with temperature, because when the molecules of a fluid are moving faster (when the fluid is warmer), the molecules can more easily slide over each other. So when you pour pancake syrup, for example, you may notice that it’s very thick in the bottle, but the syrup becomes quite runny when it spreads over the warm pancakes and heats up.

Fluid moving: Laminar and turbulent flow:

Fluid flow can be laminar then the fluid particles move along well-defined paths or stream line and all the stream lines are straight and parallel. Thus the particles move in laminas or layers glinding smoothly over the adjacent layer. This type of flow is also called stream line flow or viscous flow.
Turbulent flow is that type of flow in which the fluid particles move in a Zig-Zag way. Due to movement of fluid particles in a Zig-Zag way, the eddies formation takes place which are responsible for high energy loss.

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Article By

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Mr.N.Nagendra Kumar                       

Assistant Professor

Mechanical Departement

LAQSHYA Institute of Technology & Sciences