Operational Amplifier: Op-Amp as Differential Amplifier or Op-Amp as subtractor (With Examples)

[@ALLABOUTELECTRONICS]

The video solution of the practice problem : kzbin.info/www/bejne/rafbo2WtfcufqLMsi=ta8xrg-VeGlfZ5rb The timestamps for the different topics covered in the video is given below: 1:00 Op-amp as Differential Amplifier 6:30 Application of Differential Amplifier 9:35 Example 1 11:30 Example 2 (Effect of Biasing Voltages on output) 13:31 Example 3 (For practice )

[@hitman2754]

I face problem "in seeing resistance from this side " the input resistance is this ? Which video should I watch

[@hitman2754]

Sir please reply 🙏🙏🙏

[@jatinbhatt7826]

14:00 it can also be solved by knowing the fact that all resistances have equal value and therefore it works as an adder ckt at both inverting and non inverting terminals. Hence V+ and V- can directly calculated as 9v and -5v .

[@priyanshuparikh8145]

For those who don't know whats RTD : Resistance thermometers, also called resistance temperature detectors, are sensors used to measure temperature. Many RTD elements consist of a length of fine wire wrapped around a ceramic or glass core but other constructions are also used. The RTD wire is a pure material, typically platinum, nickel, or copper.

[@uniqueeducationcorner975]

Thank you brother your comment helped us

[@sk.iftekharulislam3678]

The homework problem solution is 4V..... individually solving the inverting part as well as the non inverting part and then summing them up together... It was a good exercise indeed....Thanks a lot and grateful for all these intuitive videos, saves hours from scattered and motionless studying...

[@parthapratimboruah641]

The answer is 4V. While calculating ....Rf = 1kiloOhm and Ri = 1 KiloOhm parallel 1 KiloOhm = 0.5 kiloOHm. And while calculating the voltage by the non-inverting input first use voltage divider (you will get 2V, 2.5V) then superposition theorem (consider the other two resistors as in parallel) ( 1 + 1/(1 parallel 1)) x (2V + 2.5 V) = 3V. Then at last V output because of that ( 1 + Rf/Ri ) x (3V) = 9 V. From inverting terminal we get Vout = -5V. So, the final answer if 9V + (-5V) = 4V.

[@yonatantamiru7756]

on inverting part we get vo1=-5volt and non inverting part weget vo2=9volt , in total giving 4 volts

[@hitarthanandrohra8846]

how can both V(non - inverting) and V(inverting) terminals have different voltages? as per the virtual ground/short concept both V+ = V- in terms of magnitude provided there is nothing mentioned in the question that these both are not equal. According to the basics of Op amps, voltage at inverting terminal is always equal to voltage at non - inverting terminal

[@roshan459]

@@hitarthanandrohra8846 oh, yeah!

[@jatinchauhan6902]

Parallel me thori hai Bhai dono 1 k ohm

[@taravanova]

@@hitarthanandrohra8846 I believe it is because the principle of super position is being used. In steady state, v+ and v- probably are equal. To solve the problem more easily, we calculate how the system would respond if various input voltages were grounded (giving different values for v+ and v-), then sum the results.

[@rudeviper]

I watched this whole palylist of 32 videos and my concept of opamp is clwar now . I am not preparing for gate but i am in 1st year of electronics in IIT BHU .

[@pravatkumar2575]

Thank you sir.I learned about opamp easily from your videos.The answer of the example 3 is 4v.(V total =V1+V2+V3+V4=-2v-3v+4v+5v).

[@voldemort7443]

I am not getting this answer please help me

[@vatsalagarwal2758]

@@voldemort7443 -(1/1)*2 + -(1/1)*3 + (1+(1/1))*((1/2)*4) + (1+(1/1))*((1/2)*5) = -2 -3 +4 +5 = 4v

[@voldemort7443]

Ye 1/2 ka factor, jo last two terms me aaya h, wo kya parallel resistance addition ki wajah se h?

[@vatsalagarwal2758]

@@voldemort7443 haan video dhang se dekh samajh aajayega

[@bharadwajkv4662]

@@vatsalagarwal2758 the answer is 1v bro

[@RiteshYadav-rc1np]

for those who are not able to solve : consider the voltage Vx ( hope you know where is the vx) 2-vx + 3-vx = vx-vo vo =3vx-5 second equation 4-vx + 5-vx = vx vx= 3 put this value in first eq .

[@manikanthbolem1328]

thank you vroo

[@chitrasingh9200]

If it is right answer then video of summing amplifier is quite complex..superposition theorem,long equation

[@shubham_2337]

@@chitrasingh9200 yeah true...no need to solve by superposition😇😇

[@arshmohan4327]

bhaiya ji answer hi likh dete poora

[@arshmohan4327]

@@manikanthbolem1328 bhai yeah bhi solve nahi hua tere se

[@sumantasarkar9861]

Basically i am a maths student and tomorrow I have physics exam .... And the topic opamp is in it... I just see these videos and I have confidence that I am gonna pass... The explanation is too good and too easy to understand.... Love it so much ... And thank you....❤❤❤

[@ALLABOUTELECTRONICS]

Wish you all the best for exams.

[@hiteshsaini5452]

answer is 4v .and i would also suggest u to put more questions of this type for practice.

[@harindudilipa1559]

Hey can u explain me im stuck i cant find the answer

[@waraysplayground26]

Yeah, I got that answer by using nodal analysis. Lesser solutions... First, I solve the voltage at V+ using nodal which is 3V. Then, because it is a negative feedback V- = V+. So, voltage at V- is also 3V. Again, to solve for Vout, using nodal, the answer is: (2 - 3)/1k + (3-3)/1k = (3 - Vout)/1k, Solve for Vout, is 4.0V... ;')

[@sukritihans8484]

@@waraysplayground26 it might have been a typo, but ig that should be (2-3)*. Thankyou so much !

[@priyanshagarwal5682]

@@waraysplayground26 will Ra be equal to R1+R2?

[@waraysplayground26]

@@priyanshagarwal5682 , actually I didn't rely on the formula. I stick with the nodal analysis when answering op-amp. Ra is not equal to R1+R2 here. :)

[@tazrilali1513]

I really love the op amp playlist. Everything is so simply explained.

[@niknam.]

Thank you SO MUCH for explaining this 9:20 diff issue. I spent too much time not understanding what the problem was in my circuit! Thank you!!!

[@Jada.Mohini]

Sir the way you are teaching is very simple and the explanation is too good ...... Thank you so much sir 🎉🎉 The answer to the last que is 4v sir.

[@Sofia-ee8vo]

Can you explain how you got 4v 🥺..

[@hridaymittal2080]

Thanks for clearing Basic ideas. Answer of given problem is 4V.

[@mustafamontaser4955]

thank you very much for your perfect explanation your follower from EGYPT

[@teja9017]

Nice!

[@varunv6309]

Where u studied

[@SGTVNewThinking]

Sol:- Resistors value is always 1 in question Applying super position theorom at uper node where (-) sign I2+I3=I1 (2-V)/1+(3-V)/1=(V-Vo)/1 5-2V=V-Vo -Vo=5-3V Vo=-(5-3V)-------1 Now apply down positive lower side superposition then I4+I5+I0=0(inside flow current is 0 in op-amp) Now, Voltage is same at both point according to rule (4-V)/1+(5-V)/1+(0-V)/1=0 -3*V=-9 V=3 Put the value in equation 1 Then Vo=-(5-9) Vo=4v Is correct ans

[@antaradey1274]

1v aa raha ha, Eqn 1 me for inverting- Vo1= 5 hoga,waha 5-3v kyu ho raha ha

[@debangshudutta3567]

yes it is correct

[@dheerajkumarbaghel_0198]

@@antaradey1274 yes

[@sashipreetamnekkanti7799]

why are you keeping solutions

[@danielmacfarlane4575]

I got 4 Volts which can be arrived at intuitively or using math. Here is my solution: This solution demonstrates that the total output is the sum of the outputs for each respective input. Vout = V2out + V3out + V4out + V5out Each output can be considered as 4 individual cases 2 cases for the Inverting Summing Amplifier and 2 cases for the Inverting Summing Amplifier. First consider the Inverting Summing Amplifier cases: V2out = - V2in x (Rf/R2) = -2Volts x ( 1/1 ) = -2 Volts V3out = - V3in x (Rf/R2) = -3Volts x ( 1/1 ) = -3 Volts In both cases the first term represents the input voltage, 2nd term the gain for each input voltage. Second consider the Non Inverting Summing Amplifier cases: V4out = + V4in x (Rg/ (Rg + R4)) x (Rf/R4 + 1) = +4 Volts x (1/2) x 2 = +4 Volts V5out = + V5in x (Rg/ (Rg + R5)) x (Rf/R5 + 1) = +5 Volts x (1/2) x 2 = +5 Volts Note, Rg represents the resistor tied to ground. In both cases the first term represents the input voltage, 2nd term the voltage divider, and 3rd term the gain for each input voltage. As mentioned earlier, the total output is the sum of outputs for each respective input. Vout = V2out + V3out + V4out + V5out Vout = -2 Volts - 3 Volts + 4 Volts + 5 Volts Vout = 4 Volts

[@indrajeetkumar8917]

One resistance is already ground. If we tied to 5v resistance to gnd then the both resistance will be in parallel so the equivalent resistance will be 1Kll 1K= 0.5K

[@NirmalKumar-wm2gr]

After watching 4 op-amp videos, now I am addicted to the introduction music :))))

[@satyakumar7523]

we can solve this problem by using summing amplifier. For inverting amplifier Vout= -Rf/R{v1+v2+v3} where R=same for all. similarly for non inverting Vout={1+Rf/Ra}×{v1+v2}/2. where R is same for all. Finally thank you sir for providing video. It is very clear to understand and learn.

[@adjeifrancis6857]

why v3 in the inverting amplifier?

[@patrickfeeney4180]

Which resistor is Ra on this case?

[@vanhoangtran8783]

I calculated in this way : V_out = - 2 - 3 + (1/2/(1+1/2))*(5+4)*(1+2/1) = 4 V. Thanks for this video !

[@miqdadphysics5624]

Answer is 4 v, using the superposition principal at each input,then find their superposition. Amazing content 💖

[@thraithashakam963]

Thank u so much sir! I had trouble in linear circuits. By today my trouble was cleared. Once again tq sir!

[@nishapawar3368]

I enjoy this music every time....it makes me happy😺

[@mrtelcom4005]

without understanding..?!😂😂😂

[@nishapawar3368]

@@mrtelcom4005 no...I understand these videos :)

[@makshithsaai2821]

Op-amp explanation is awesome sir , it helped me a lot .

[@mausamkumari4641]

answer is 4 , it seems easy by ur good explanation... Thanks sir

[@prashikkhare14]

V02 is at non inverting (1+Rf/R1) *vin So it is not 9v it's 18 . 18-5=13v

[@th3airraidsir3n5]

Thank you so much! I always had trouble with understanding op amp circuits, makes perfect sense now!

[@th3airraidsir3n5]

Don’t know if you already have but would you make a video about RC parallel circuits? I have no clue what they do or how they work I want to understand from an AC standpoint as I am particularly interested in audio circuits.

[@fusedaatma]

For inverting terminal inputs, one can also use summing amplifier concept to find output. Anyways thank you so much AAE.

[@chidanandadatta4695]

We can also follow basic method from where we derived basic formula (kcl+super position theorem)..ans 4.... thanks a lot for this valuable lecture

[@sohamghag1726]

Correct bhai

[@Market121]

Ans 4v -2-3+4+5 = 4volts When consider 2v Vout = (-1/1)*2 which is 2V when 3v Vout = (-1/1)*3 which is 3V When 4V Vout = (1+(1/1))*V' where V' is get through voltage divider rule (Same resistance/Total resistance)*total voltage which is V' =(1/(1+1))*4 =2V so, when 4V consider Vout = 2*V' =2*2 =4V When 5V V' = (1/(1+1))*5 =5/2 =2.5V then Vout = (1+(1/1))*V' = 2*2.5 = 5V so total Vout = -2-3+4+5 =4Volts

[@aadityavaidya1318]

Thank you boss 🫡❤

[@jaisejohnson]

wow such a fine video.This is the best video I found on the topic.Thank You.

[@tirthzaveri3567]

thank you sir i wil gate 4V and also thank you for this video series of (OP AMP)

[@zvirus0074]

Vout = 4V Through applying the superposition theorem for each input voltage.. We will get 4 output voltages.. Combining all these output voltage... The result will be = -2-3+4+5 = 4 V

[@parvezmahmud6963]

How? I guess, 1V Because the v3 (which is connected to the ground) of the non-inverting terminal has effect on the input voltages.

[@greninja2607]

@@parvezmahmud6963 yeah 1 v is the answer

[@SuPeRTRoNeRD]

@@greninja2607 Okay great, that is what my answer was as well. Thank you very much!

[@prashikkhare14]

V02 is at non inverting (1+Rf/R1) *vin So it is not 9v it's 18 . 18-5=13v

[@shreyaagrawal2830]

the videos are really good. the output voltage in the last question is coming as 4V for me...is it right?

[@kishanprasadappana2093]

Yeah

[@AYUSHSINGH-pv3pl]

yupp

[@saptarshisahoo5075]

Thank you...your videos are best. and Answer is 4v.

[@shobhitpandey8821]

Answer is 1 volt -5 from inverting input terminal and 6 for noninverting input terminal

[@Harshavardhan-zr2ip]

V3=0, V=(v1+v2)/2

[@shaktisiwach6097]

A huge thnxxxx to uh sir.......i dnt hv words to express how much ur video lectures had helped me ....uh hv made electronics so easy nd interesting for.....student like...me.........😊😊😊....

[@sreedharsmarts9140]

Sir ans Vout is 4V And tnks soouch for this all op amp concept explanation

[@anushrigupta7539]

Can you explain how you got 4V ? I literally got confused by seeing the circuit.

[@johnkyingilisi4395]

I get 4V too. With love and respect from Shiraz

[@bhartibhavnani399]

Ans is 4V seems little late 😅 Great way of teaching Suggesting u to make videos on other parts of physics also it will be great 😄

[@saifkhan-xf6qb]

In the examples you have solved by using superposition i.e solving sources individually. These can be solved by using formulae derived for difference amplifier i.e. Vout= Gain ( V2-V1). And Gain = Rf/Ri

[@prathamdabee7476]

Can you show me how to do it

[@prathamdabee7476]

Please

[@KoushikMalOfficial]

your teaching skill is great.. we need more videos upon electronics

[@greeshwarrs6469]

u completely rocked and made me understand a concept in practical manner instead of sticking only to theory❤❤❤❤

[@tpsicmin]

Thank you Sir Amazing Explanation

[@stockfish3379]

Such a dedicated teacher u are

[@Phyamath]

thanks sir, I appreciate your method of teaching, answer is 4v, plz acknowledge

[@satyaveersinghrawat4398]

Hi Sir thank you for such a nice series of lectures. Doubt are 8:07 Min Onwards 1. How Input impedance seen from upper terminal is R1 and lower is R1+R2. How? 2. Similarly at 8:24 Min how input impedance is 2R1. Thanks in advance.

[@ALLABOUTELECTRONICS]

To find the input impedance at the upper terminal, just connect external source at that terminal. The ratio of that voltage to the current supplied by that source will give the input impedance seen through that source. And while calculating that, we will consider all other sources in the circuit as zero. That means the non-inverting terminal will get connected to ground via two resistors. So, if you apply the KVL at the inverting end, then you will get Vx / Ix = R1. Likewise, on the lower terminal, if you follow the same procedure, at the inverting end, you will get Vx / Ix = R1 + R2. Similarly, at 8:24, to find the input impedance, you need to find Vin / Iin. Because of the virtual ground, the voltage at the inverting and non-inverting node will be same. So, while finding input impedance, for simplicity, you can assume that both are connected together. So, whatever current (Iin) that is passing through upper resistor R1, same current will return through lower resistor R1 and will go back to the negative terminal of Vin. So, if you apply the KVL, then it is Vin = 2R1 *Iin. Or Vin / Iin = 2R1. I hope, it will clear your doubt. If you still have any doubt, then let me know here.

[@satyaveersinghrawat4398]

@@ALLABOUTELECTRONICS Thank you for your response. I have solved all the cases according to your guidance and quite satisfied. For 8:24 Min, I am satisfied with the logic but still not able to figure out that what is happening with R2 which is connected between non-inverting terminal and ground. Current through that R2 will be 0, it is giving me a bit dissatisfaction even though I know solution is correct. Can I share the solutions (by any means), what I did, for crosschecking the correctness?

[@shreeyashrasal8574]

Thanks sir, I liked the way of teaching and explaining every bit in detail. Vout is 4V.

[@eitantal726]

This video makes it more complicated than it has to be. Here's how to understand it simply: When you have an op-amp with a negative feedback, it will copy the voltage from + into -. *It's that simple*. All that's left is to figure out what the voltage on vout is.

[@msrizwi7869]

And thanks for helping us by such a great teaching style

[@oinamdhananjoysingh3715]

in the example1..v(out)=6v but if we apply the formula for v(out)=R2/R1*(v2-v1),ans=5v...or i am confusing about R2.. at 6:22 min u expalin this formula.U mean same value of R2 in the formula derived at 6:22 min.

[@radhey04ec]

Since last week I am looking for the Answer How designer decide to use R1 and R2 at Non inverting terminal as Voltage Divider for achieving differential amplifier??! & I found here Thanks dear

[@kishorgoodday276]

From you i got answer , i made correct in v01 and gone wrong with v02 bcz i not use voltage divider now i got ...thanks dear

[@saikumarsingam9010]

In the derivation part you considered resistance values are equal in the input of V2 and input of V1 and equal value as Rf.. But in the calculation part you have taken different resistance values for everything.. Is it necessary to take same resistance values for input of V2 and V1 and Rf?

[@anon00089]

you've probably completed your degree by now, but if anyone else has the same question, this is just the method for derivations I'm pretty sure, you start with the general case and derive the particular cases (when input resistances are equal).

[@tanishqchaudhary8254]

ans of last ques is 4 V and Thank U sir for this quality of lectures U r best

[@raunaksharma498]

Sir, we can also get the subtraction operation done by using the approximation R2/R1 >> 1 so that, 1+R2/R1 = R2/R1 and hence, Vo = (R2/R1)(V2-V1).

[@phitsanuboy]

Sorry for my newbie,I also confuse about R2/R1 >> 1, it mean 1+R2/R1 -> 1+1 = 2 the result difference between (R2/R1) -> 1 and (1+R2/R1) -> 2 quite a lot... In my thinking..

[@VersatileAnthem]

i got the actual proof from your video.thank you so much.what reference book do you follow ?

[@vinaykumarkajana7881]

I dont know anything in analog electronics but now i am getting through it Thanks...

[@aritradas9523]

tere bhai jaisa koi hardich nhi hai

[@karthikbabu9053]

Simple and precise explanation. Really superb👍Thank you✌️

[@avneetkashyap7001]

hello @allaboutelectronics can you please comment me why V02 process of solving is different in example 1 and example 2 thanks for such an hard work

[@kendolemalleswara]

in syllabus all cover to lecture for better understanding. these lecture are very good

[@hemlocklannister6206]

Answer is 4v .. thanks man.. amazing video

[@jayakumar6780]

Sir if u provide videos on module based it will be added advantage... Any how your videos are like bible for electronics students and engineers too..

[@nikitameena3061]

Sir if V1 is grounded Vo=-5 and when V2 is grounded Vo=27/2 so overall V1+V2= 17/2 Is this right ?

[@mdminhajsk1265]

Best video in you tube, thank you so much

[@RishabhSharma10225]

Amazingly explained. Thank you so much !

[@missakasms]

Here, to the ones who are struggling to get the answer, the answer is 4V, you get -5V from V1 and +9V from V2, add them together you get 4V

[@synecdocheanimacion9021]

how can someone struggle to solve that really I'm cse 1st year that too in a private college still I was able to it solve it mentally... in the internals itself they ask questions much harder than this I wonder what they will ask in endsem 🙂

[@omarrz94]

Hi! what happens if V1 is fed with AC and V2 with DC? I am trying to solve an exercise in which V1 branch has a capacitor along with that 'R1', so I assume that when charged it releases DC but I am confused by how it works... seems like a band pass filter maybe?

[@ALLABOUTELECTRONICS]

Without looking at the circuit, it is difficult to tell the working of the circuit. But many different types of circuits related to opamp has covered and many examples have been also covered. You may check the opamp solved examples playlist. Perhaps you will find a similar type of example you are looking for.

[@omarrz94]

@@ALLABOUTELECTRONICS I'll check them! thank you

[@curiousbud2366]

Is 4v the correct answer 🤔

[@motofriend-vlog8566]

Getting equal gain means we have apply V2= R2/(R1+R2) That mean whatever the value is in the voltage.

[@dalenassar9152]

Among other things, isn't the input resistance into the non-inverting input equal to the Thevinin resistance of the two resistors of R1, R2 of the voltage divider? ANOTHER GREAT VIDEO!!! THANKS,

[@lijinavajeev599]

Excellent explanation

[@vaikh8450]

Sir if we are applying the formula R2/R1(V2-V1) then why the answer is different

[@prabhatp654]

bro, the resistances are different.

[@agstechnicalsupport]

Great explanation of differential amplifiers.

[@aashutoshpradhan1763]

4 v is ans.....great explanation

[@manojgs2017]

Really awesome and very informative videos... nice presentation and the groundwork is highly appreciable. The best KZbin channel for those who want to go deep in to the World of electronics .👏👏👏 Thank you mannnnn!!!!!!💥💥💥💥

[@bhargavtharun]

hello sir your analytical approach is perfect but when we do in simulation for 2nd example circuit the out is not 12v it is 10v

[@ALLABOUTELECTRONICS]

Because, often the saturation voltage of the op-amp is less than the biasing voltage. In fact, it's true for most of the op-amps. There are some rail to rail op-amps, whose saturationvoltage is close to biasing voltage. That's why you are getting 10v.

[@GAUTAMKUMAR-or7rh]

Answer of 3rd problem is 4V......is it correct...?

[@noweare1]

The last example is more interesting than it looks. The feeback ratio for the inverting input is not the same as the non-inverting. The ratio for the non-inverting side is Rf/ (1k // 1k) => 1k/0.5k since we have at the inverting input two 1k ohm resistors in parallel to ground. When I first did this problem I got the wrong answer.

[@tanujkasal]

Thanx ,I was facing the same problem.

[@MANISHKUMAR-ee2ty]

Thanks you sir! for this lecture. answer of the last question is 4V. is it correct?

[@ALLABOUTELECTRONICS]

Yes, that's correct.

[@tharindudissanayaka5863]

excellent explanation. thank you sir.

[@codebrex1715]

Dear Sir, I have a problem on Differential Amplifier. This is from Robert Boylestad. Determine the output voltage of an op-amp for input voltages of V i1 = 150 uV, Vi2 = 140 uV. The amplifier has a differential gain of Ad = 4000 and the value of CMRR is: (a) 100. Ans: (i) 45.8 mV (when Vd = 150 uV -140 uV) (ii) -34.2 mV (when Vd = 140 uV - 150 uV). How is it possible that we end up getting two different Vo values (one positive and negative with different magnitude). Which one is correct?

[@Swagstar626]

Vout=gain(V noninverting - V inverting) based on input given to the answer can be negative or positive but not more than baising voltage

[@Gabriel-V]

never experienced such perfect explanation

[@PTeja-tr1qw]

Thanks alot for better understanding ans is 4v

[@suvardhansingh7528]

Sir, in tha example 3 for practice hare is a problem in case of non inverting v(out)=(1+Rf/R1) so for R1 hare is two resistant how to separate them??

[@ALLABOUTELECTRONICS]

It will be the parallel combination of two resistors. (1k || 1k). Answer of that question is 4V.

[@suvardhansingh7528]

ALL ABOUT ELECTRONICS yes sir ( - 2-3+4+5) =4 Thank you so much sir, your op-amp video is very helpful for preparation JAM exam

[@sarathkogila6222]

Very nice example sir

[@SumitChaudharykPS]

ALL ABOUT ELECTRONICS Sir iss mei do voltage hei na 4v and 5v uss ko kese solv. Kare

[@adda4career]

@@ALLABOUTELECTRONICS sir in example 3 while we considering 2Volts source alone at R1 resistor place one 1k resister is connected to ground. Is there any effect of 1K resistor on R1? What is value of R1 in that case? Please give a solution to me sir

[@himanshigoplani3483]

I got the answer as 4V ... And I guess that is correct ... But may I know , will there be no effect of bias voltage +-15V on the answer ....??

[@missstorytellertelugu7473]

Sir why can't we use direct formulae to the examples I.e vo=(-rf÷r1)(v2-v1) sir plz tell Me..

[@ALLABOUTELECTRONICS]

It can be used only when resistors used in the feedback and voltage divider circuit at the non-inverting terminals are equal. Let's say in the feedback the resistor is R2 and resistor R1 is at the inverting terminal. If the same resistors are also used as a voltage divider at the non-inverting terminal then also, you will get that expression. Else the expression will be different. therefore it can't be applied directly. I hope it will clear your doubt.

[@missstorytellertelugu7473]

@@ALLABOUTELECTRONICS tq sir For clarifying my doubt tq..

[@parvezmahmud6963]

After addidng extra resistance to the positive terminal, why there is no change in the equation of V1? Previously, V+ was V2 directly, now it's not. As they are virtually grounded.

[@tamannasharma1568]

sir, as we put feedback in the circuit at the output terminal, then the OPERATIONAL AMPLIFIER will only give the output after the feedback signal is reached to it and not before?

[@ALLABOUTELECTRONICS]

It happens very instantaneously. ( The operation of circuit with feedback)

[@sagnikmukherjee6604]

4V. Please let me know if its correct.

[@Seerat.Bashir]

The practice example... Do I have to find four output voltages corresponding to 4 input voltages acting one at a time.... N then add all of them?

[@mahendraverma5931]

4V Sir, this video is very heelpful to me......thank u

[@me_suryans]

Why not explaining the Superposition theorem, Im first year Btech student following this Playlist.

[@darlingbrother4852]

Superb sir.....excellent explanation.....thanks a lot....

[@sohammitra8657]

The intro music is very good...

[@djchutki72626]

thankyou sir. my answer is 4v.

[@YahiaAlwarha]

I have a question in a minute 8:18 you said Zin=2R1 why ? can you explaine its please?

[@BhanuPrathap]

At 4:58 Are the resistances R1 and R2 are connected in series ,that means no current through the op amp inverting terminal .

[@ALLABOUTELECTRONICS]

Yes, here it has been assumed that the op-amp is ideal.T hat means no current is flowing into the op-amp terminals.

[@BhanuPrathap]

Thanks for clarifying 😀

[@sudeshnaguharay5187]

in the inverting amplifier video you have explained about the buffer circuit , there you have used the same circuit as that of a instrumentation amplifier and here you have short circuited the inverting input voltage to that of the vout. please explain me this point...

[@ALLABOUTELECTRONICS]

That is the design of buffer circuit, where the output is short-circuited with the inverting input terminal and input is applied at non-inverting input terminal.

[@YoungsProton]

My question to u is... in ideal case, OPAMP should have high input impedance.. Why is the input impedance in differential amplifier low? Even if you dont respond.. Please know.. = Excellent videos... Really helped me to get a clear perspective on OPAMP.. Thank you...

[@ALLABOUTELECTRONICS]

I have already explained it around 8:00. Please go through it.

[@YoungsProton]

@@ALLABOUTELECTRONICS Got it.. when I saw your instrumentation op-amp video... Thanks..

[@Lina-025]

Life saving, thank you

[@vigneshhere28]

In this sum on the non-inverting terminal first 4v voltage source acted so short circuit the 5v then the resistance of 1 ohm and 1ohm are parallel then simply it 0.5 ohms then answer will be 8/3 how do u eliminate the 5v source resistance 1ohm????

[@JonathanDeWitt1988]

@All About Electronics How do you make it so the gain factor k = 1? In the adder version of the Op-Amp you showed how to make the gain factor 1. That would be nice here too. Thank you for the good video.

[@ALLABOUTELECTRONICS]

At 6:30, if you see, when R2 = R1 then gain will become 1. That means Vo = V2 - V1. I hope it will clear your doubt.

[@JonathanDeWitt1988]

@@ALLABOUTELECTRONICS Thank you. I missed that even though it is clearly there in the math.

[@kukurei]

Can i use this circuit in audio application to cancel out a signal coming in the inverting input by injecting an audio signal in the non inverting input? I want to see if I can use this to cancel an echo or crosstalk?

[@ALLABOUTELECTRONICS]

Yes. Only thing need to be ensured is that, the gain of the amplifier should not saturate the output and the op-amp should be able to drive the next stage. (The output source current of the op amp should be sufficient to drive the next stage)