Monday, January 28, 2019


B-Tech -ECE.
Applied for DGFS-09.
Got Medical slip.

Interview Date: 2 July 2009


This is Raghavan.
Interview panel consists of 5 people but one of them was checking my certificates only. Remaining four interacted more. Just before attending the interview I got admission in IIT-KGP. But it was not there in sponsored courses it was my first question. 

1) IIT or BARC?

I said BARC.

  When the interviewer asks you such type of questions then a youtube video
          A Talk With Shubham Dabir
will help you to tackle them. In this he has given 4-5 PSU interview experiences as he is GATE 2017 topper (AIR-75).

  Now they asked me to tell them if I knew what type of questions being asked by the panel to previous interviewees.
This was a shock for me. I said I remember one. Asked me to tell the question and solution. I told.
Then I was given a block diagram. Input is the clock. Output should be 

00 , 01 , 11, 10 .

I was asked to design that block and derive it step by step.
 Next they asked me to pen down my fav 5 subjects.

1. Networks

2. EDC

3. Digital Electronics & Microprocessor

4. Analog 

5. Control Systems.

Then they asked me questions like.

2) If we want to indicate 0 and 1 using glowing LED, how to do that?

3) how LED works?

This is one of the favorite questions of BARC scientists.


4) how do you drive the LEDs with your block.

Do you need extra cost? If so design that. How much current does a typical gate output would be?

5) some typical questions on TTL logic.

Voltage level, fan in, fan out ... And so on.
How you will get the power supply for your gate.

Then that question stretched to the topic like AC generation.
Conversion to DC.
Rectification and Regulation.
Zener diode construction and working principle.

6) Application of feedback in voltage regulators.

For all these questions I asked to draw block diagrams and asked to explain their level of satisfaction.

7)Now they came upon OP AMP.

Pin diagram of 741.
Design voltage amplifier of particular gain.
Inverting, noninverting...How will you get that gain?
How can you apply KCL directly at an opamp input terminal?
Ideal opamp circuits.
Why opamps are not ideal?

DC defects of the opamp in a voltage amplifier.

What happens if we interchange the connections to pin 2 and 3.

Draw output. Power supply voltage range. Saturation conditions. A range of resistance in the feedback path and input terminals.

8) Explain LPF ckt with an opamp.

Draw output for some typical inputs.
LPF with passive components?

9)what happens if few resistors/capacitors are added series/parallel?

And output for some typical inputs.

Finally, one irregular signal was shown. 

10) suppose this is voltage across capacitor/inductor

Derive and plot the current waveform for each.

I was asked to leave after that and asked to wait for 5 min. Later I got a medical slip, thank God. I can't describe.

They didn't ask about my project.
My interview lasted for around one hour. Throughout my interview, sometimes I could not recollect and answer some questions in a flash they made me think.
Provided me enough hints.
My panel was amicable but sometimes I felt that I'm nowhere, I'm not up to the standard they wanted. Overall it was a very good experience...!!!

  Here you can find Electrical Interview Questions.


Friday, January 18, 2019

INTERVIEW EXPERIENCE AT ISRO (Indian Space Research Organisation ), New Delhi.

Interview Date: 2nd Jan 2017.

 An interview panel was of 10 senior scientists took my interview for roughly 25–30 minutes. I am giving the entire interview process here.

For BARC exam preparation and to practice interview questions click here.

   They didn't ask me about any favorite subject or favorite topic. They just started asking various questions.


1) What was your final year project? 


2)What are 3 practical uses of your project?

I answered it properly. 
Then they told me to draw the circuit diagram of the switch relay circuit used in my project.


3)Any 5 differences between an open loop system and closed loop   system.

After my answer, they put some cross questions regarding bandwidth and stability of both the systems.


4) Types of Modulation and their principle applications.

Then they started asking about CDMA, GSM and UMTS standards.
They told me to elaborate on the differences between TDMA, FDMA, and CDMA in a practical manner.
       I answered them properly as they are the most asked interview questions for ECE students and prepared them well. From here they jumped to the definition of Lossless channel, Random channel and Deterministic channel and told me to draw each on the whiteboard.


5)Can you tell us about Huffman coding basics and significance in data compression?

As I have created a YouTube video on data compression using Huffman coding I had no problem with that.

Another panel member asked me about LEO and MEO. I answered about their application ranges but I was unaware of their heights. He also asked, “Does the mass of satellite has any impact on its velocity or not”. I answered it with confidence.
      Then another member jumped into the power electronics and started asking about Triac, IGBT, Power Mosfet, SCR, SCS and Snubber circuits. I was confident only with SCR hence answered that and said “ Sorry Sir I don't know” for the rest ones.
Due to my weak response, they shifted their gears and asked me about the diamagnetism and their use in Maglev trains which I answered perfectly.

Then they asked the differences between PD, APD and PIN diode which I answered with ease.

At the end stage of Interview panel head started telling the silent panel members “ Thoda Thoda aap bhi pucho Sir, Bahut hua theory thoda sa practical pucho isse.

Then he asked the last question of my interview


6)Can you design the automatic dusk down traffic light? 

I said yes and designed the circuit of LDR based dusk down an automatic traffic signal. After coming out of the hall I realized the blunder that I forgot to put a comparator in the circuit diagram before LDR to compare the intensity levels.

           Unfortunately its not a success story. I was one among them who's dream of joining ISRO as a scientist remained dream again.

It's hard to share the failure story but I think my experience, statics, and my
mistakes could help others in their preparations.


⏩ISRO( Indian Space Research Organisation ) , Delhi.

Interview Date: 22nd Nov 2016.
Selected as Scientist SC in ISRO.

Hi, I am Navneet Kumar.

As I entered the room there were about 8-10 interviewers sitting on the other side of a U shaped table and in front of them in a chair, I was supposed to sit and answer their questions. First, the Chairman asked me for my introduction which I gave very briefly, then he asked me 3 of my favorite subjects.

I said " Digital electronics, Signal theory, Electronic devices".

Digital expert asked me the following questions-

1)What is FPGA?

I did not know much about it and just gave him its full form.

He said" explain its functionality "

I went silent and said I don't know sir.

2) Have u read about logic families?

Yes, sir!

3)which is the fastest logic family and why?

(I gave a good answer and he seemed satisfied)


4)why CMOS is used more in practical applications?

I answered it well


5)Explain Noise figure, Fan out etc etc..

I answered them 

6)Difference between DTL and DCTL?

I explained DTL but had not heard about DCTL till then! so he let me go with that.


7)Explain SRAM and DRAM?

I answered it.


8)What are PLDs and what is the Difference between PROM and PLA?

I answered it decently enough.
Then he passed on the baton to signal theory expert.


9)what is Digital signal processing?

I somehow tried very hard to explain it which was certainly not enough for him and he asked me a counter question.


10) why DSP is used?

I had not prepared anything for that so I could not answer it.
he said, "it's okay if you don't know".
Then came from out of the blue "Analog electronics expert".
I was sent to the whiteboard right behind my back.


11)Design straight line equation y=mx+C with an op-amp?

I made it and he said, "Don't you think it'll have design issues, I saw my design and gave one alternative solution to which he was fairly satisfied."
then he quick-fired me with 4-5 op-amp theory questions like Slew rate, CMRR, gain bandwidth product etc atc.. (I answered them all)

Chairman then looked into my BIO-DATA form and said, "You made a project on 8085 microprocessor?"

"Yes," I said.
He asked me to explain it?
I explain it to its entirety and he was okay with that
Then he asked me some project specific questions like:


12)why did you use RST7.5 and RST6.5?(I had used interrupts in my project) etc etc..

Then again came the Digital expert.


13)Difference between TRAP, RST5.5, RST6.5 and RST7.5?

I answered.


14)Difference between EPROM and EEPROM? Which ROM did you use in your project?

I told him the difference and also I had used EPROM and told him why I used it.
As I was near to the board so he thought of utilizing it again.


15)Draw a timing waveform through a D flip flop and indicate set-up time, hold time and propagation delay in it?

I drew it and he made sure I make it very neat so that he could clearly see every delay in detail and gave instructions throughout in the process.

16)Master-slave FF working, Direct bandgap semiconductor etc..

Then I came back to the chair and chairman said "OK! you can go now"
"Thank you", I said.

I was giving interview unhurriedly and was keeping calm in answering every question. Also, I gave all my answers in English so I think it's better to answer them in English as most of them are comfortable that way.
Being spontaneous is very important as they don't give much time to think.

I scored 129/240 in written (51 attempted 45 correct 6 incorrect) and got 74.40/100 in the interview and was at panel position 66/201 after the interview.


Wednesday, January 2, 2019

⏩BARC (Bhabha Atomic Research Center)

Interview Date:26th June 2009.

OCES Interview.

Observe the level of BARC interview questions. Let's hear in the words of the candidate.

"I was the first candidate that day, first of all, I wished good morning to the panel. On return the main person wished me. Then he asked me where I was studying and how waw the accommodation facilities. Actually, they were trying to make me relax.

Then he asked me "tell your 5 fav subjects... I told

1. Linear Integrated ckt.
2.Control system.
3. Signal and system.
4. Digital Electronics.

Interrupted in between they didn't allow me to tell 5th subject and started questioning.


1)Draw inverting amplifier of gain 100.
2)Draw noninverting amplifier of gain 100.
3)Draw differential amplifier of gain 100.
4) Suppose CMRR of the above differential amplifier is 100db then find common mode gain.
5)Find the exact output of the differential amplifier.
6)Common mode voltage of the differential amplifier.
7) Consider a 10v dc connected in between inverting and noninverting terminal. And 2.5v dc connected between noninverting and ground. Now asked to calculate output vtg, common mode vtg, and difference mode vtg.
8) What is the input impedance of the inverting amplifier.....
And continued...


1) Draw an arrangement to indicate the selected pin index and the output state of MUX.
2) Generate a clock signal for a watch(i.e. of 1Hz).
3) Generate a 120v 60 Hz clock signal.
It can be generated d using high tension transformer and related ckt .but didn't know.
4) How a stable clock can be generated.
Ans is using crystal oscillator.
5) The frequency of oscillation of crystal oscillator.

6) What is the practical significance of Q factor?
7) Draw graph of Q factor of series R-L-C ckt.
8) What is really mean by an increase in and decrease in Q factor in ckt?

Signals And System.

1) we have got three identical bandlimited signals with us ...we are required to send them one after other allowing a specific delay between each of them. Also, we have to code these signals before transmitting.
2) What all ckts should be used before an ADC.
and so on up to 1:45hours...." I was interviewed.