Sohail Ansari

Memristor (An invention that will change the whole Circuit Theory)

memristor-symbolTill now we are studying about the three element in the circuit theory i.e. Resistor,inductor and capacitor.There is another element proposed by Leon Chua in 1971 known as Memristor (an invention that will change the circuit design in the 21 century). From 2008 HP is doing research on this element.

Memristors are basically a fourth class of electrical circuit, joining the resistor, the capacitor, and the inductor, that exhibit their unique properties primarily at the nanoscale. Theoretically, Memristors, a concatenation of “memory resistors”, are a type of passive circuit elements that maintain a relationship between the time integrals of current and voltage across a two terminal element.
memristorIn this diagram we take voltage current flux and charge along the sides of square and make a relation between adjacent then we came to know the resistance inductance and capacitance have a relationship as shown in figure but one block is empty i.e. there is no any relation between flux and charge. So Leon Chua invented this relation and proposed a new element known as memristor in 1971 and in this way fourth element came in to an existance. It is predicted that 20 element yet to come in future excluding these four element.


  1. Memristors can retain memory states, and data, in power-off modes which allow the system for quicker boot up since information is not lost when device is turned off.
  2. Use less energy and produce less heat. So heat sink is not required and the size of the machine will get reduced.
  3. Eliminates the need to write computer programs that replicate small parts of the brain.
  4. It has higher density which allow more information to be stored in small chip.
  5. Conventional devices use only 0 and 1. Memrister can use anything between 0 & 1.
  6. It is faster than flash memory (allow digital camera to take pictures with no delay).


  1. Non-volatile memory applications: Memristors can retain memory states, and data, in power-off modes which allow the system for quicker boot up since information is not lost when device is turned off. There are already 3nm Memristors in fabrication now by HP.
  2. Low-power and remote sensing applications: coupled with memcapacitors and meminductors, the complementary circuits to the memristor which allow for the storage of charge, memristors can possibly allow for nano-scale low power memory and distributed state storage, as a further extension of NVRAM capabilities. These are currently all hypothetical in terms of time to market.
  3. Crossbar Latches as Transistor Replacements :Solid-state memristors replace transistors in future computers, taking up a much smaller area. There are difficulties in this area though, although the benefits these could bring are focusing a lot of money in their development.

So with the inventions of this element the whole electrical circuit will change in future and library containing lakhs of books will be replaced by one single chip whose dimension will be 1cm square.
Hope u have got some research oriented information. If u have any query then please comment below.
To read about Ultra capcacitor, click here
To know some more article related to EE stream go to EE Article page.


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Ultra Capacitor

column2-nrel-diagram_ultracapAn Ultra Capacitor is Electric double-layer capacitors (EDLC), also known as super capacitors, are electrochemical capacitors that have an unusually high energy density when compared to common capacitors, typically several orders of magnitude greater than a high-capacity electrolytic capacitor.
Generally, capacitors are constructed with a dielectric placed between opposed electrodes, functioning as capacitors by accumulating charges in the dielectric material. In a conventional capacitor, energy is stored by the removal of charge carriers, typically electrons from one metal plate and depositing them on another. This charge separation creates a potential between the two plates, which can be harnessed in an external circuit. The total energy stored in this fashion is a combination of the number of charges stored and the potential between the plates. The former is essentially a function of size and the material properties of the plates, while the latter is limited by the dielectric breakdown between the plates. Various materials can be inserted between the plates to allow higher voltages to be stored, leading to higher energy densities for any given size.

Screen Shot 2015-08-17 at 10.38.34 PMUltra Capacitors do not have any dielectrics in general, but rather utilize the phenomena typically referred to as the electric double layer. In the double layer, the effective thickness of the “dielectric” is exceedingly thin, and because of the porous nature of the carbon the surface area is extremely high, which translates to a very high capacitance. Generally, when two different phases come in contact with each other, positive and negative charges are set in array at the boundary. At every interface an array of charged particles and induced charges exist. This array is known as Electric Double Layer. The high capacitance of an Ultra capacitor arises from the charge stored at the interface by changing electric field between anode and cathodes.

• High energy storage. Compared to conventional capacitor technologies, EDLCs possesses orders of magnitude higher energy density. This is a result of using a porous activated carbon electrode to achieve a high surface area.
• Low Equivalent Series Resistance (ESR). Compared to batteries, EDLCs have a low internal resistance, hence providing high power density capability. • Low Temperature performance. Tecate Group PowerBurst® products, with their use of patented technology, are capable of delivering energy down to -40°C with minimal effect on efficiency.
• Fast charge/discharge. Since EDLCs achieve charging and discharging through the absorption and release of ions and coupled with its low ESR, high current charging and discharging is achievable without any damage to the parts.

• Low per cell voltage. EDLC cells have a typical voltage of 2.7V. Since, for most applications a higher voltage is needed, the cells have to be connected in series.
• Cannot be used in AC and high frequency circuits. Because of their time constant EDLCs are not suitable for use in AC or high frequency circuits.


  1. Applications requiring a short duration power boost.
  2. In Low power,Capacitors are extensively used as power back-up for memory functions in a wide range of consumer products such as mobile phones, laptops and radio tuners.
  3. Super capacitors are also used to provide fast acting short term power back up for UPS applications. By combining a capacitor with a battery-based uninterruptible power supply system, the life of the batteries can be extended. The batteries provide power only during the longer interruptions, reducing the peak loads on the battery and permitting the use of smaller batteries.
  4. It is also used for energy storage for solar panels, and motor starters.
  5. Using super capacitors in EVs and HEVs to facilitate regenerative braking can add 15% to 25% to the range of the vehicle. At the same time, super capacitors can provide an effective short duration peak power boost allowing the prime battery to be downsized.

For any query please leave a comment below.
To know some more article related to EE stream go to EE Article page.


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PSU Registration Link Through GATE 2016

psu-mainCheck the PSU Recruitment Through GATE 2016  below and register yourself by clicking the link provided for each of the respective PSU.

  1. Power Grid Corporation Limited (PGCIL).
    Start Date: 15 Jan 2016
    Last Date : 29 Feb 2016
    To Apply, Click here
  2. National Hydro Power Corporation (NHPC).
    Start Date: 01 Jan 2016
    Last Date : 01 Feb 2016
    To Apply, Click here
  3. Bharat Broadband Network Limited (BBNL)
    (Not came yet.. will update soon)
  4. Bharat Petroleum Corporation Limited (BPCL).
    Start Date: 29 Dec 2015
    Last Date : 30 Jan 2016.
    To Apply, Click here
  5. CEL Solar.
    Last Date : 29 Jan 2016
    To Apply, Click here
  6. Hindustan Petroleum Corporation Limited (HPCL).
    Last Date : 02 Feb 2016
    To Apply, Click here
  7. Indian Oil Corporation Limited (IOCL).
    Last Date : 07 Feb 2016
    To Apply, Click here
  8. Odisha Power Generation (OPGC).
    Not came yet… will update soon
    Note : Remaining PSU have not opened till 02 jan 2016. I will update when it will be open. So stay tuned with the blog. For further queries, comment in the comment section given below.
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My Interview Experience in Infosys (2014)

infosys-logo-baseline-PNGGuys, this was my second interview just after the Wipro. Although selection procedure was less (only 2 rounds) but little bit tougher than wipro.

Written test was taken online .There were two rounds: 1. Written     2. HR Round
1. Written Test: Written test were conducted in three sections.
(a)The first section includes 15 questions from Arithmetic Reasoning and                           Analytical Thinking which was very easy and the time given for this                                     was 25 minutes.
(b)The second sections include 10 questions from aptitude which u have                           to solve in 30 minutes. The aptitude question was from Probability,                                       Permutation and combination, Time and speed, percentage.
(c)The last section includes verbal which the toughest among the three                           sections. There was 40 questions and has given only 35 minutes.                                         There was 2 long comprehension, 5 questions from syllogism ,                                             sentence correction, data sufficiency. Most of the students gets                                           eliminated because of this section only.
There was a sectional cutoff (9 question from 1st section, 6 question from aptitude and 22 question from verbal).Total 900 students were enrolled for the written test out of which only 204 students were selected for HR Round.

2. HR Round : I was shortlisted for the HR round.Next day i went for the interview at 7 AM morning and they called me 6 PM in the evening. I knock the door and said…

Me: May i come in sir?
Interviewer: yes plz come
Me: May i sit sir?
Interviewer: yes plz be sit
Interviewer: What is you name?
Me: Sohail Ansari
Interviewer: So sohail will u plz tell me something about yourself?
Me: told
Interviewer: Plz tell me about your project?
Me: told
Interviewer: Do u know c++?
Me: yes sir, i know some basic features of c++.
Interviewer: plz explain
Me: i explained all the features.
Interviewer: have u done programming in C?
Me: yes sir
Interviewer: write a bubble sort program?
Me: i was writing the program and he was going through my resume step by step. after 2 minutes he told me to tell the logic. i told him.
Interviewer: How many iteration this program will take?
Me: i told him the answer which was wrong.
Interviewer: ok i m done.. u may go now.
Me: thank u sir.

This was my shortest interview (only for 5 minutes). I thought may be i will not select because he has not given time to explain all the things. Also i had given one wrong answer.
next day the result out. out of 204 students, approx 150 were selected and i was one of them.
Interview Tips: If u want to get placed in infosys then prepare well for written test. The written test was little bit tougher than any other campus drive. once u crack the written test then chances of getting placement will be around 80%. Focus more on English because in interview they only check your communication skill and ability to learn new things. Second most important thing they see is your resume. Make resume perfectly (they see project section & achievement section in your resume.) Good Luck.
To see my Wipro Interview, Please Click here.

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