Thursday, May 21, 2015

HOW TO PREPARE FOR GATE (EC AND IN)- ELECTRONICS COMMUNICATION ENGINEERING AND INSTRUMENTATION ENGINEERING

Name: Aditya Narayan Nanda
AIR: 10 (IN- GATE 2015)
College: College of Engineering and Technology , Bhubaneswar 

PREPARATION STRATEGY

Self-motivation is most important during GATE preparation. Make you own  strategy and please dont follow others. You have your own strength, weakness and interests. Focus on your weak areas (BEST METHOD TO FIND WEAK AREAS IS TO GIVE A LOT OF FULL LENGTH MOCK TESTS). If you are in final year then you may not have enough time. So don't go for part tests , go for Full length Tests only. Improve your effectiveness rather focusing on how much hour do you study. I read Bhagvat GITA (Bhagavad-Gītā As It Is  by A.C. Bhaktivedanta Swami )  daily for a better day. You can also read DAILY INSPIRATION by ROBIN SHARMA.  These helped me a lot in staying positive during my preparation. 

 Follow standard text books and use internet to know the derivations of formulas. Syllabus is very vast and you cant remember all the formulas.

Math is the language of Engineering. So first start with maths and don't practice maths , understand the physical meaning behind it. For example vector calculus can be easily understood by studying EMT simultaneously.

Then comes the Network Theory. You have to ace Network portion in order to excel in Electrical/Electronics engineering. Follow any standard text book and solve numericals on it. Sometimes one problem may have different solution methods and you can discover them by practising a lot of questions.

Then for core part follow a sequence so that previous subject can aid to the next. For example Electronic Devices and Circuits (EDC) then Analog and Digital Electronics .  Network Theory and them Electrical Measurements. Signals and systems then Communication . Control System and then Transducers. Electromagnetic Theory then Antenna and finally Microwave.

Solving previous year GATE and IES question is a very important factor in preparation. If you have time then solve EE EC IN previous year papers.  You can channelise your preparation strategies according to the previous year paper. Be positive and  have faith in yourself . Respect your teachers and parents. Their blessings can do miracle in your life. 

REFERENCE BOOKS

Reference means you have to refer these books during preparation. Don't try to Read the whole text book (IF PREPARING FOR GATE 2016) . Choose any  one book to learn the theory and concepts and solve questions from other books. The best thing about foreign author or standard text books is that the number of example questions given are conceptual and very less in quality . If you understand something clearly then there is no need to solve many questions on same concept ( even you can skip GATE previous year questions also).  If you are in 2nd year then you may follow these books during your semester exams. 

1. MATHEMATICS

# if you have time then read "Mathematical Methods for Physicists by ARFKEN, WEBER and HARRIS"- (NOT REQUIRED FOR GATE) . You will get to know, how mathematics is used to model modern world problems. after all we are engineers and we are here to solve problems , not just to pass exams and get degree ( actually these are also important :P ) .

2.NETWORK THEORY


3.ELECTRONIC DEVICES AND CIRCUITS


4.ANALOG ELECTRONICS


5.DIGITAL ELECTRONICS


6.SIGNALS AND SYSTEMS


7.COMMUNICATION SYSTEMS

8.ELECTRICAL AND ELECTRONIC MEASUREMENTS


9.CONTROL SYSYTEM


10. PROCESS CONTROL


11.ELECTROMAGNETIC FIELD THEORY AND ANTENNA THEORY


12. TRANSDUCERS


13. ANALYTICAL OPTICAL AND BIOMEDICAL INSTRUMENTATION

  • SHORT NOTES ACCORDING TO PREVIOUS YR GATE Q 
  • Made Easy Theory Book 
  • MOCK TESTS

OTHER PRACTICE BOOKS
  • GATE - Electronics Communication Engineering (ECE) Practice Book by Kunal Srivastava (IES TOPPER)
    • Buy GATE

SHORT NOTES
I will scan my short notes and Upload it after August, 2015 ( After admission in Masters Programme)
© Aditya Narayan Nanda
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Wednesday, May 20, 2015

CALCULATING INPUT IMPEDANCE OF A BJT CIRCUIT




© Aditya Narayan Nanda
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What is Fourier Series ? a graphical explanation

While surfing the internet I came across a beautiful explanatory video of fourier series.
Watch it and feel the excitement of engineering.



© Aditya Narayan Nanda

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Monday, February 9, 2015

OSCILLATOR CIRCUIT ANALYSIS - EASY METHOD



© Aditya Narayan Nanda
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BJT HIGH FREQUENCY ANALYSIS





© Aditya Narayan Nanda
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Monday, September 10, 2012

OP-AMP (non-inverting) - LM324


An operational amplifier (op-amp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. (WIKIPEDIA)

 Amplifier is a device which takes small voltage in input terminal and spits out large voltages in output terminal...

 the gain of amplifier is the amount multiplied with input to produce the desired output...

 for example if u take a 1V input and get 5v output then the gain of amlifier is =5

 an OP-AMP has generally 5 important pins

 i> inverting input 
ii> non-inverting input
iii> +Vcc
iv> -Vcc
v> OUTPUT

 in input terminal only use signals ...

 OP-AMPS can't creat voltage out of nothing!!! so we have to use a bit larger supply volatage than the desired output voltage

 so if i have to get a 10V oupput then i have to use atleast 12V supply voltages... dont try to apply high voltage it may damage your device so always reffer the DATA SHEET
if your supply voltage s very less then you will get clipped OUTPUTS

smooth voltage sources are important for a amplifier to give a uniform output signal so use two suopply batteries, hooked up in series  with capacitors given below :


CLASSIC NON-INVERTING AMPLIFIER:
here we use a LM324 OPAMP with max current rating = 20mA

 you can set the gain using resistors ...
the circuit diagram is given below


THE GAIN FORMULA :




for simplicity use R1=1k (fixed) and then choose R2 according to you gain......


CLICK HERE for the derivation of the gain formula ( find it in thr 9th page )

 APPLICATION:

 SPY-MICROPHONE

  a simple small microphone has a output signal of 20mV
and to run a EAR-BUD we need atleast 2V
so gain must be 100

 using gain fomula r2= 100k
so gain= 101 nearly equal to 100

 OK TIME TO UNDERSTAND THE CIRCUIT BLOCK BY BLOCK :


BLOCK A
use 9V supply to power up the mic and use R1 to limit the current

 BLOCK B
is a high pass filter and the capacitor blocks the supplied 9v DC and passes the signal

 BLOCK C
r2 and r1 is set to a gain of 100
so in output pin we get a 2V signal 

 BLOCK D
10K variable resistor is used to change the supply voltage of LS(ear-bud) to control the volume 

2V output is sufficient to run the earbuds but can't run a LOUD SPEAKER as a loudspeaker needs high power supply which will kill the LM324 ..... so i have googled for a home theater OPAMP and found LM1875 OPAMP, which is great for loud sounds in your home.....you can supply more voltages and use high valued resistors to get LOOUUDDDDD SOUNDDDDDD!!!!!!!!!! the circuit diagram is same for both LM324 N' LM1875

DERIVATION OF GAIN( NON INVERTING) 
*video will be uploaded soon 

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Friday, September 7, 2012

RC-LOW PASS FILTER

© Aditya Narayan Nanda

LOW PASS RC FILTERS:

 WHAT IS THIS??
FILTERS are used to change the frequency content of a audio ... that means u can clip off some of the frequency( in some range) and pass others .. wow!! sounds great.....

understand any thing??? i know your ans is NO!!!
so lets see this practically::

first download VLC MEDIA player and open the song : given up by Likin park

i choose this one because this band is my fav and songs have almost every frequencies ... cool na??

OK now play the song and go to the equalizer control and then change the frequency bars as shown...





have you noticed any change in sound?? probably your answer is YES..
its just like your pre-loaded FULL BASS mode.  

look at bar setting what you have done?? u have just allowed the low frequencies and blocked the higher ones that mean you have clipped off high frequencies and allowed lower one.. that means you have made a LOW PASS FILTER...



<<notice you can still hear the song but some frequencies are clear>>

HOW TO MAKE LOW PASS FILTERS??
u need resistor, capacitor, DC source , jumper wires and bread board

Example Circuit:


this works so because the voltage of capacitor can't instantaneously change. and you have a resistor in series which slows down the charging process: OK THAT MEANS IF RATE OF CHANGE IS HIGH then OUTPUT VOLTAGE IS NOT GOING TO REPRODUCE IT IMMEDIATELY .. BUT WHEN YOU HAVE LOW FREQUENCY THEN RATE OF CHANGE IS SLOW SO YOU GET THE EQUIVALENT OUTPUT.

IN PRACTICAL CIRCUITS YOU HAVE TO CHOOSE A HIGH RESISTANCE AND LOW CAPACITANCE TO BUILD A LOW PASS FILTER

 cut-off frequency formula:











so our example filter has a Fcutoff = 1591.54 Hz that means any frequency greater then this is not going to sound your ear buds!!!

how to choose r c values for your own filter?
FIRST use the speaker data sheet and look for the max current... then look at your source DC voltage... the choose a resistor to limit the current .....then use your cut off formula to calculate the capacitor value.. very easy.... 

 SOME SIMULATIONS :
below i have given 3 examples. R1 and C1 are filter elements and R2 is  a load resistance and stands for head phone or speaker etc.
in all cases R1=10K, C1=10n 
so
Fcutoff= 1591.54 Hz
::::::::::::::::::::::::::::::::::::::::::::::
1:WHEN INPUT FREQUENCY IS LOWER THAN CUT OFF FREQUENCY:
Fcutoff= 1591.54 Hz
Applied Frequency= 50 Hz
Here applied frequency(in green color) is very low so output frequency ( in red color) is same as input...
::::::::::::::::::::::::::::::::::::::::::::::
2:WHEN INPUT FREQUENCY IS HIGHER THAN CUT OFF FREQUENCY:
Fcutoff= 1591.54 Hz
Applied Frequency= 2000 Hz
Here applied frequency(in blue color) is slightly high so output frequency ( in green color) is clipped off and we get very low amplitude output...


 ::::::::::::::::::::::::::::::::::::::::::::::

3:WHEN INPUT FREQUENCY IS MUCH HIGHER THAN CUT OFF FREQUENCY:
Fcutoff= 1591.54 Hz
Applied Frequency= 200000 Hz


Here applied frequency(in green color) is very very high so output frequency ( in red color) is totally clipped off... so we get a nearly zero output

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NEXT TUTORIAL:
 RC HIGH PASS FILTERS then REAL AND IDEAL FILTERS
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