HOUSEHOLD APPLIANCES AND THEIR POWER RATINGS

One unit of Electricity saved =one unit of Electricity generated

In the modern society every house is equipped with certain electrical appliances. It is better if all know the rating of each for better utilization of it and saving of power consumption by using them for a shorter duration. Operate the high wattage equipment for lesser duration leads to the consumption of lower units.

Appliance	Watts	Appliance	Watts
Central Air Conditioner	5,000	Electric blanket	200
Electric Clothes Dryer	3,400	Shaver	15
Oven	3,000	Waterpik	100
Hair Dryer	1,538	Well Pump (1/3-1 HP)	480-1200
Dishwasher	1200-1500	Laptop	60-250
Coffee Machine	1,500	Plasma TV	339
Microwave	1,500	LCD TV	213
Popcorn Popper	1,400	25” color TV	150
Toaster oven	1,200	19” color TV	70
Hot Plate	1200	12” black and white TV	20
Iron	1,100	Stereo	30-Oct
Toaster	1,100	Satellite dish	30
Microwave	500-1500	Radiotelephone - Receive	5
Room Air Conditioner NA	1,100	Radiotelephone - Transmit	40-150
Vacuum Cleaner	500	Lights
Water heater	479	100 watt incandescent bulb	100
Sink Waste Disposal	450	25 watt compact fluor. bulb	28
Espresso Machine	360	50 watt DC incandescent	50
Dehumidifier	350	40 watt DC halogen	40
Blender	300	20 watt DC compact fluor.	22
Humidifier	300-1000	CFL Bulb (60-watt equivalent)	18
Video Game Player	195	CFL Bulb (40-watt equivalent)	11
Standard TV	188	CFL Bulb (75-watt equivalent)	20
Monitor	150	CFL Bulb (100-watt equivalent)	30
Computer	120	Heaters***
Portable Fan	100	Engine Block Heater NA	150-1000
Ceiling Fan	100	Portable Heater NA	1500
Can Opener	100	Waterbed Heater NA	400
Curling Iron	90	Stock Tank Heater NA	100
Stereo	60	Furnace Blower	300-1000
Cable Box	20	Clothes Dryer - Gas Heated	300-400
Clock Radio	7	Well Pump (1/3-1HP)	480-1200

-------------------------------------------------------------------------------------------------------

Article by

Mr.B.MuraliKrishna

Department of EEE

Laqshya Institute of Technology and Sciences (LITS) , Khammam

Laqshya Institute of Technology and Sciences

CLASSIFIACATION OF ENGINEERING MECHANICS

Mechanics is defined as the science which describes the conditions of rest or motion of bodies under action of forces.

Engineering Mechanics refer to a subject which deals with the application of principles of mechanics for the solutions of engineering problems. It is useful and essentially required in the analysis of forces acting on machine parts, heart engine parts, roof and bridge truss, heat engine and population of aircraft etc.,

Engineering Mechanics can be classified as follows:

Classification of engineering mechanics:

The engineering mechanics is mainly classified into two branches. They are

1. Statics                   2. Dynamics

1. Statics: Statics deals with the forces on a body at rest.

2. Dynamics: Dynamics deals with the forces acting on a body when the body is in motion.

Dynamics further subdivided in to two sub branches. They are:

            (a) Kinematics:   This deals the motion of a body without considering the forces causing the motion.

(b) Kinetics: This deals with the relationship between the forces acting on the body and resulting motion.

IMPORTANCE OF MECHANICS TO ENGINEERING:

 1)For designing and construing to dams, roads, sheds, structure, building etc.

2)For designing and controlling of fluid flow.

3)For calculation and estimation of forces of bodies while they are in use.

4)For designing and manufacturing of various mechanical tools and equipment. 

5)For containing and co-ordinating the various part of mechanics.

6)For designing a fabrication of rockets. 

-------------------------------------------------------------------------------------------------

Article by

V.Ravinder.

Asst.Professor , Mechanical Department

Laqshya Institute of Technology and Sciences (LITS) , Khammam

Laqshya Institute of Technology and Sciences

Software Testing Quality and Challenges in Software Testing

When a program is executed, the developers of the program are concerned with the correctness and performance of the implementation of the program. Software engineers must ensure that the software systems must achieve an appropriate level of quality. 

The software quality assurance is defined as the measuring and monitoring the strength of development process. It is also known as verification. i.e. verifying the process is nothing but SQA.

There are two types of factors in software quality.

(1) Technical factors

(2) Non-technical factors

The technical factors are concerned with the following 

(1) The software should meet with the customer requirements (i.e. functionality of s/w)

(2) The software should meet with the customer expectations (i.e. usability, reliability and performance)

The non-technical factors are concerned with the following 

(1) The cost to purchase the license of software

(2) The time to release into the market

Hence to achieve the good quality software, generally the following principle is followed.

    SQA+SDLC+SQC.

The actual testing takes place at SQC (Software Quality Control).

The quality is defined as matching with the customer expectations and customer requirements.

Now we deal with the validation of the process.

The validation means that the actual testing of software from the end user point of view.

It checks that whether the product is fit to use or not. (In verification, we check that whether the product is fit to specification or not). 

Challenges in Software Testing

In general, the test engineers face the following challenges or risks during testing.

(1) Lack of time

(2) Lack of resources

(3) Lack of skills

(4) Delay in delivery

(5) Lack of communication.

To overcome the above mentioned challenges in testing, generally the testing teams follow the ad hoc testing styles.

There are different types of ad hoc testing styles.

(1) Buddy testing

(2) Monkey testing

(3) Exploratory testing

(4) Pair testing

(5) Be bugging

-------------------------------------------------------------------------------------------------

Article by

K.V.Rama Rao,

Asst.Prof . Department of CSE

Laqshya Institute of Technology and Sciences (LITS) , Khammam

Laqshya Institute of Technology and Sciences

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

---------------------------------------------------------------------------------

Article By

--------------

Mr.K.Pithamber                

Assistant Professor

CSE Department

LAQSHYA Institute of Technology & Sciences