Thevenin's Theorem Explained (With examples of Independent and Dependent Sources)

[@ALLABOUTELECTRONICS]

Minor correction: 5:30 In Case 1, the value of Vth will be 15 V instead of 5V.

[@rahuljaiswal4409]

it is -15V

[@danieleyitoyo8089]

10-10(-0.5) -10(-0.5)=+5 so, 10+5=5

[@alihajjhassan84]

So helpful thank you!!

[@gaddamful]

can u please mention this in the description instead. also good idea wioth the time stamps

[@ALLABOUTELECTRONICS]

I have already Pinned this comment.

[@unnimaya5681]

I just came here to see what to do with the dependent sources. But I got to learn why this theorem is needed. Thanks for that.

[@bingebites1_9]

anybody who is confused about voltage Vab in case 1 see below: just apply KVL at node A like this: 0=(Va-10)/10 + (Va-20)/10 SO 2Va = 30 Va = 15v Note: B is taken as ground so Vab is now only Va as Vab= Va-Vb

[@madhur7590]

You've applied kcl not kvl

[@TriscuitFTW]

@@madhur7590 he did node voltage to prove there's a mistake. i literally looked to the comments because i was certain that first mistake was an error

[@sivaarun4351]

Wow thanks....I needed this😁

[@piyush501]

Thanku brother' my mind was blowing regarding this before seeing your comment ❤️🙌

[@nitingautam6762]

Yes. Vab in first case is 15 volt

[@deepakdhuriya76]

Best explanation i have ever seen on KZbin ... Thanku sir for helping students like us

[@aminulislamishmam5607]

you're the boss. you explain the theory well and also the practical applications. Thank you

[@GLu-tb1pb]

review: Only independent sources: remove selected resistance, calculated voltage via mesh analysis and resistance via removing sources Independent and dependent: Apply KCL on dependent sources and short A and B to find volt and resistance only dependent: apply 1v/1A source from B to A to find the resistance, as it is equal to Va (Volt = 0)

[@ahmadfarris8308]

This video helps me a lot. Clear explanation + good examples. Thanks @All About Electronics.

[@AJ-et3vf]

Awesome video sir! Thank you! Exactly what I need!

[@mnada72]

5:22 The minus in the last equation should be replaced by plus Thank you for the video, it's really of value

[@KavyaRam]

One doubt...why to make independent sources zero while calculating thevenin's resistance? What is the significance of this point?? Also what does thevenin's voltage actually mean

[@nikhilkapoor8868]

In case 1..there is a mistake...Vth is 15V not 5V

[@ALLABOUTELECTRONICS]

Yes, you are correct Nikhil. Thanks for mentioning it.

[@gaddamful]

do u start reading comments before commenting

[@saumeenphansalkar6722]

@@gaddamful no you moron he commented after readding

[@mohamedabubacker.m831]

I didn't understand how to to find Vab in case 1 pls explain it....

[@ALLABOUTELECTRONICS]

Here node B is the reference node. (i.e Vb = 0V) So, Vab = Va - Vb = Va. So, we just need to find the voltage at node A. And it is equal to 10V - (voltage drop across 10-ohm resistor) I hope it will clear your doubt.

[@mohamedabubacker.m831]

@@ALLABOUTELECTRONICS thanks a lot

[@2023noone]

@@ALLABOUTELECTRONICS 1. is not Vab=Vb-Va, not Va-Vb Can you apply KVL in open circuit, since it is not a loop as point A and B are disconnected?

[@rishiprusty3166]

When u solve the problem if u hints the eqn very helpful 2 us....btw ur vedios is awesm and it is very helpful me in my study...tq

[@student6830]

He made a small mistake in example 1, but he already corrected it, I don't know why 99% of the comments are about that mistake? Let's just appreciate his effort instead.

[@engsherif4657]

Great thanks for you Dr sherif ahmed from egypt

[@saigowtam2253]

Please don't apply direct steps. It will be difficult to understand. If we have that capacity to understand that direct steps we don't need see your videos, we can do on our own.

[@santoshpal8612]

Thanks God u understand that direct steps

[@uygarbaran8515]

I’m so confused about the 2nd case when he shorted the resistance and the dependent source. How?

[@analysisdigwd8721]

yeah ,me too.Why is it that the dependent source is alsoshort circuited as the terminal A and B is short circiuted

[@anglotenglish6001]

He doesn't explain it well. The reason is that when he applies the short circuit across the terminals A and B, the voltage across those terminals is zero, thus the voltage of the dependant source (3.VAB) is now also equal to zero, so can be replaced with a short circuit.

[@SoumyajitMondal]

@@anglotenglish6001 oo yes yes. Thanks for your explanation

[@dianaalothman9831]

@@anglotenglish6001 no he was mistaken when he short circuited the dependent voltage source. what you said is only true if the dependent voltage source was connected in PARALLEL to a and b terminals then that would be a short circuit. the dependent source actually becomes connected in parallel to the 2k ohm resistor

[@prithvigupta8215]

@@anglotenglish6001 thanks man .you saved me from confusion.

[@fouzanbaig1963]

This video clear my all concepts of dependent and independent sources

[@rajeshbandi3070]

Why in the second case, didn't short ckt the voltage source

[@Natyler03]

simple , clear and right explanation! Thanks! Greetings from Paraguay

[@pooyaimani8331]

Your explanations are so cool 💯

[@chillacombs8790]

hi am a CE student....my lecturer wasn't that clear especially on obtaining the thevenin resistance....but lol...you made it simple sir..thumbs up!

[@physicsdiva1871]

Nice explanation

[@Niha1399]

Sir I didnt understand how did u get Vab=10-(10i)

[@ALLABOUTELECTRONICS]

To find, Vab, KVL has been applied in the loop. Now, Vab = Va- Vb ( the Potential difference between Node A and B). As node B is reference node, so the voltage at that node will be zero. Now, the voltage at Node A will be 10 - (10I) (that is 10V - voltage drop across 10-ohm resistor, using KVL) And hence, Vab = 10 -(10I) I hope it will clear your doubt. If you still have any doubt then do let me know here.

[@othoiothoi4299]

sir how is node b a reference node

[@ALLABOUTELECTRONICS]

See, node B is at zero potential. Or in another way, if say, it is a ground of the circuit. And in the circuit generally, the node with zero potential is considered as the reference node. I hope, it will clear your doubt. If you still have any question then do let me know here.

[@inspiratex]

what if both resistors are not equal

[@saimanimorri8942]

Sir voltage at node A 10-(10i) ala aindii

[@ParneetKaurChemistry]

Thank you.. I understood it well😊

[@Gaffari2000]

Very helpful, thank you!

[@prachiaggarwal433]

amazing explanation

[@jayaprasadb2044]

Sir suppose if we take 20v in order to find out vth then value of vth will be change

[@Akash-hq5xf]

very nice section i liked it bro

[@vipulsingla4486]

your lecture is very usefull and easy to understand🤓🤓

[@ashvinisalunke2775]

Hi please make video on Transfer Function of Electrical Circuits. Thank you, your videos are helpful.

[@harshvardhangavandi7733]

In case 3, is the 3i dependent source a current-controlled voltage source, if not then how did you subtract 3i from Va in case it is not a voltage source (that would be like subtracting current from voltage otherwise).

[@kumudk4kk93]

Yes, I think it is a CcVs , and the symbol of a dependent voltage source is also there. If it was a current source, an arrow(symbol of a dependent current source) would have been used.

[@universe1072]

really very helpful

[@shuvadipbhowmick7610]

you are great sir

[@student6830]

You are so smart dude

[@muhammadfaizanahmedkhan6371]

Could you please tell me the applications of Thevenin's , Norton's, Reciprocity, superposition and maximum ower transfer theorem.

[@arindam_03]

Please explain more easily and give regular examples for B. Tech students

[@anglotenglish6001]

For those confused about the shorting of the dependent source in part 2: The reason is that when he applies the short circuit across the terminals A and B, the voltage across those terminals is zero, thus the voltage of the dependant source (3.VAB) is now also equal to zero, so can be replaced with a short circuit.

[@mayankraj9618]

in # case 2 why don't we remove 1kohm resistance across AB..(we removed it in case 1)

[@spelunkerd]

I"m still trying to intuitively understand why we short circuit a voltage source but open a current source when calculating Thevenin's resistance. Why the difference in how these two are manipulated? I guess voltage makes sense. After all, there is no resistance in an ideal battery. The best I can come up with as far as a current source is the way it is usually in parallel to a resistance, and so opening the source, which will never change depending on the load characteristics, is fair. Anybody have other ideas?

[@sreerams8660]

its 15V and not 5V in Case :1

[@harpyb3951]

bhai kya sahi banda hai gay for him

[@abkrikot]

At 8:45 in case #2 while explaining Super node this stumped me Vx - Vth = 3Vth , You Jumped from Vx-Vth = 3Vab and equated Vab to Vth

[@hemantsingh1253]

You have calculated wrong value of Vth in case 1 I think it would be 15 volt

[@ALLABOUTELECTRONICS]

Hey Hemant, yes I have already mentioned that in the pinned comment.

[@jaydipprajapati5763]

Very blnice video and easily understood that.

[@new-jj5il]

Simply superb

[@ashar6118]

ckt contain dependent src, i got value of vth is 15v if am applying kcl..is dis value rgt?

[@sumanth9929]

Sir, @ 10:59 you've eliminated the 2 ohm parallel 2 ohm resistances to 2 ohm resistance. But without making parallel formula how would it be 2 ohm? It might be : 2*2/(2+2) = 1 ohm ??

[@ALLABOUTELECTRONICS]

If you closely observe, the 2 K resistor is in parallel with AB terminals (which are short-circuited). That means their effective resistance will become zero. And in the equivalent circuit, there will be only 5V voltage source in series with 2 K resistor. I hope it will clear your doubt.

[@tedharasta]

I was confused but you did it wrong. Can you please change the value of Vab from 5v to 15v

[@goflow6425]

Sir...u said that Vab=10-10(I)....how u give value of A as 10 & B also 10?????

[@harishhreddy5234]

Exactely i too had that dought

[@ALLABOUTELECTRONICS]

If you see the left side of the A and B. There is a 10V resistor in series with 10-ohm resistor. Here Node B is considered as a reference node. So, the voltage between the two nodes will be the 10V minus voltage drop across the 10-ohm resistor. If I is current in the circuit then Vab = 10 - (10 ohm x I) I hope it will clear your doubt.

[@abhishekchaudhri691]

i didn't understand why and how 1 ohm resistor got short circuited when A and B r shorted

[@ALLABOUTELECTRONICS]

When A and B are short-circuited, it offers zero resistance. So, anything in parallel to it will also offer zero resistance. Because all current will flow through the short circuit. And that's why 1K resistor will also get short-circuited. I hope it will clear your doubt.

[@BentHestad]

Sir, Your channel is great!

[@anshpratapsingh5279]

TOO GOOD. THANK YOU!

[@shreyasuresh8291]

I have a doubt in the case 1 to find R th u short circuited the voltage sources, but in the case 2 why you dint short circuit the 5 v voltage source??? Plz clear my doubt

[@ALLABOUTELECTRONICS]

Because in case 2, the circuit contains the dependent source. So, there is a different procedure for finding the Thevenin's theorem in that case. Please go through the example, and after that if you have any doubt then do let me know here.

[@pravinkumarsharma200]

Vth in first case will be 15V. Do review and update.

[@adnanbajwa27]

In case 2 if the independent voltage source was present in the place dependent voltage source and vice versa than after short circuiting does the independent voltage source gets short circuit or not

[@viveksamani7924]

@ALL ABOUT ELECTRONICS at 4:30 when you just applied kvl and wrote the equantion as 10=10 I +10 I + 20 according to the arrow you dram (yellow one , clockwise)........but its wrong, the correct equation would be 10= 10 I + 10 I - 20 as we are moving from higher to lower potential of 20V source as the arrow indicated by you is clockwise........i may be wrong!

[@ALLABOUTELECTRONICS]

Please check it once again. You will get it. Just start from the 10V voltage source in the clock wise direction. Since the potential is rising (negative to positive voltage, let's consider it as positive. As per the direction of the current, we will have voltage drop across two 10 ohm resistors. And once gain for 20V voltage source, since we are moving from higher to lower potential, so there will be a voltage drop. So, three terms in the KVL equation will be negative. The equation would be like +10 - 10I - 10I - 20 = 0 Or, it can be written as 10 = 10I + 10I + 20. I hope, it will clear your doubt.

[@sharminmonika8887]

Nice tutorial. ,By the way .....should we always use 1 A as test current in the 3rd case ?Actually,I found the value of Thevenin's resistance varied for other test currents.

[@ALLABOUTELECTRONICS]

Any value of current source can be used as test current. Based on the value, voltage across the current source will change. But ratio of V/I should remain the same. The advantage of choosing 1A current source is that, denominator is 1. So, calculation becomes easy.

[@amoghprabhu106]

If possible I may have made multi likes.

[@КевинКоршунов]

I assume the answer is {-5V}, given the direction of the current I = -0.5A therefore in that direction it goes through the negative terminal of the voltage source making it -10 - 10(-0.5)=Vab using(KVL) Vab= -5V, I assume that is the right answer...

[@ALLABOUTELECTRONICS]

You have applied KVL incorrectly. If you are considering 10V voltage source as negative (Negative to the Positive terminal) then drop across the 10-ohm resistor should be positive. So, if you consider negative to positive going direction of the voltage as positive then KVL equation would like 10 - (10)(-0.5)- Vab =0 , And if you simplify it then Vab= 15V. I hope it will clear your confusion.

[@manibalan2141]

Why was I1 = -1A in third case at 13.20. plz help

[@daiyaan3427]

how did he get 10-10i for v in case 1, can someone explain?

[@rahulmeena3269]

Sir if a circuit contain only independent then can we apply 2nd method i.e the method of short circuit and finding Isc

[@akshayvhatkar3382]

Please add one more video about Norton's theorem

[@AdmMusicc]

In case 1, since the points A and B aren't connected, why didn't we take the 10 ohm resistances in series?

[@ALLABOUTELECTRONICS]

Because we want to find the equivalent resistance across terminal A and B. What you are saying would be true if we want to find the resistance at some other point. Let's say the points where the 10V voltage source is connected there we want to find the resistance. In that case, both resistors would come in series. I hope it will clear your doubt.

[@sid573238]

Basic info is not available

[@yec-praneethKondeti]

bro akkada dependent source sum lo ab terminals short circuit cheste 1kohm ,dependent source zero enduku aindi

[@Abhishek-hi9tx]

Best💥💥💥🔥🔥🔥🔥🔥

[@rahiabrar8400]

I have a doubt. If the V in the final reduced circuit is thevenin voltage then how come the potential difference across A&B is thevenin voltage because as there is a resistance in series with equivalent voltage of circuit the voltage across terminals will not be the same as the equivalent V. Can you please elaborate?

[@ALLABOUTELECTRONICS]

It is the representation of the linear circuit. Or I would say using Thevenin's theorem you are getting an equivalent circuit, which has Thevenin's voltage source in seires with the Thevenin's equivalent resistance. And across that circuit generally load is connected. (Across terminal A and B of the circuit). So, when you turn off all the independent sources and find the voltage across AB that's circuits equivalent voltage. It's not the voltage that you get across the load. Of course, it will be different. And it will be RL*Vth/(RL + Rth) . I think you got confused with it. Isn't it?

[@yankeefan031]

In case 2, why is the V used in the equivalent TH circuit 5 and not .5 as calculated at the beginning of the problem

[@ALLABOUTELECTRONICS]

It is 0.5V, Please check at 11:41 in the video.

[@successzone4034]

thx sir for good explanation

[@NoXYPLaysYt]

Voltage between A and B should be 15 V

[@singiri697]

Sir in the 1st sum y u took thevenin voltage across AB with 10 ohm 10V....y cud v not take thevenin's voltage with 10 ohm and 20 V on the otjer side?

[@ALLABOUTELECTRONICS]

Yes, it can be using 10 ohm and 20V source as well.

[@hemantsawant9624]

There is a mistake according to me in case 2 while you consider the dependent current source and 2 nodes as a super node and applying KCL you forgot to keep in mind the current going in and out and mentioned all the currents to be incoming current thus all positive signs in the equation kindly verify and respond.

[@homeshwarideotale7550]

Plz do minor corrections, in 1st case V=15 not 5....it take our lot of time to understand ur mistake and for a while we doubt our application.... So plz change this asap

[@ornilhasan6845]

For you subtitle circuit Couldn't see clearly

[@veritasiumaequitasius3530]

I'm sure this would be a great video, but I can't understand what you're saying. It would help immensely to practice accent for the language your speak in. There are also accent neutralization classes available. :)

[@ravikumar-jm7gj]

Can u displace the formula for every example for every vedio then we calculate the example like can u keep the formula in brackets before the calculation then we can understand that this formula is used in this step if u put this we easily understand that this formula is used in this step

[@ALLABOUTELECTRONICS]

Hey Ravi, that's good suggestion. Yes, I will do so from now on each video. So, that you all can easily understand.

[@sankalpwavekar2865]

Make a video about electronic 11th standard exam

[@splinter1817]

lol there are many sources go find them

[@sudhakiran495]

Please upload this video again after modifying the vth value in case 1

[@shanthankasarla4920]

Yes I am talking about case 1 @ Vab

[@Cheyansh_Tiger]

in case 2 ,if dependent source value replace by 20i then how will write node eqn

[@shivasai8547]

Sir explain some more problems on thevenins therom plz

[@ALLABOUTELECTRONICS]

Many problems have been already covered on the second channel. Please check this playlist. kzbin.info/aero/PLH9R5x7JVXCEvlSCakgkrfdHfxBU25MYf More problems will be uploaded there.

[@savyasanchighose5176]

sir pls upload video of Norton's theoram for lelectrical network

[@ALLABOUTELECTRONICS]

I have explained Norton's theorem at the end of the video. Please check the description for timestamps. I think it is at 14:42

[@hemanth3744]

How do you found Vab in first case (please respond)

[@ALLABOUTELECTRONICS]

Vab is the voltage between node A and B. Vab = Va - Vb. Node B is a reference node and is at ground potential. Therefore, Vb = 0. So, only you need to find the voltage at node A. The same has been found by applying KVL. I hope it will clear your doubt.

[@mohitkwatra9587]

Please tell that why current source is replaced by open ckt and voltage source by closed ckt In detqil you told it in vedio i cudnt understand it

[@ALLABOUTELECTRONICS]

In Thevenin's theorem, while finding Thevenin's equivalent circuit any source is replaced by its internal resistance. And voltage and current sources which are used during the examples are ideal sources. Ideal current source has infinite input impedance and ideal voltage source has zero series internal resistance. That is why current source is replaced by open circuit and voltage source by short circuit. I hope it will clear your doubt.

[@kerensobol1645]

there is also a problem in case 2, you sayd that to find Rth we need to shorten all sources and you didnt shorted the 5V source.

[@ALLABOUTELECTRONICS]

Well, that's the case when all the sources are independent. When the circuit contains a dependent source then the problem will be treated differently. (which is the case in the second example, as 3Vab is the dependent source) I hope it will clear your doubt.

[@keerthiraja9860]

At 9:58 Why A&B terminals were shorted?

[@rushalmshah]

To find the short circuit current through terminal A and B.

[@funofun6317]

Please upload clearly for students sir . To find Vth we using delta method. But here is more different. No one use this please upload as useful

[@dimi5929]

Ι didn't understand case 3. Vth=OV But then we take Vth=1.2V in order to find the Rth. Why?

[@ALLABOUTELECTRONICS]

well, that's not Thevenin's equivalent voltage. Its the voltage across the 1A Test current. In the circuit, when there is no independent source, the Thevenin's equivalent voltage is zero. What we can find is the Thevenin's equivalent resistance or impedance for such a circuit. And since the circuit does not contain any independent source, so we need to apply the external excitation either in the form of voltage or current to find the equivalent resistance. I hope it will clear your doubt.

[@dimi5929]

@@ALLABOUTELECTRONICS Thank you ,I have two more questions. 1.When there was a short circuit we said that the Rtotal of the pararrel resistor and the resistor of the short circuit is 0Ω so we removed it from the circuit(case 2) and therefore the voltage of the pararrel resistors was 0V .However ,the current 1A has a voltage of Vab=1.2 Volt? 2.In case 3 we didn't remove the 4Ω resistance that's pararrel with the short circuit ,like we did in case 2,and we didn't say the Rth is the 6Ω that remains in series with the dependent voltage source.(In case 2 Rth was the remaining in series resistance of 2kΩ) ..why?

[@hemenchamuah2244]

Nice video sir.....Sir can V(th) be negative???

[@noweare1]

It can be a negative voltage.

[@jeremyyoung3343]

Can you please explain again why "short circuiting" the AB terminal in Case 2 ends up "short circuiting" the rest of the circuit as well?

[@ALLABOUTELECTRONICS]

In case 2, when we short circuit two terminals A and B, 1k resistor will be in parallel with short circuit (or ideally zero ohm resistance), hence the equivalent resistance of that combination will be zero. Now, as terminals A and B are short circuited, so potential difference between node A and B will zero or we can say that VAB=0. So, dependent voltage source 3VAB will also be zero. Now, again if you redraw the circuit then 2K resistor is again in parallel with short circuit terminal. So, it's equivalent resistance will be zero. And hence, eventually both resistors and dependent voltage source will get short circuited. And we end up with 5V voltage source in series with 2K resistor. I hope, it will clear your doubt. If you still have any question then do let me know here.

[@jeremyyoung3343]

EGG SELL LENT explanation. I understand it in the context of equivalent resistance! Thank you.

[@md.nasiruddin6608]

@@ALLABOUTELECTRONICS nice explanation

[@dipenprajapati7469]

Sir please make video on Norton's theorem

[@infinitx1330]

could have made the explanation more lengthy and elaborate

[@lavanyaramesh1241]

In finding vth y r u not calculating voltage at AB due to 20 voltage source?????

[@ALLABOUTELECTRONICS]

In this example, the motive is to find the voltage at node A, which is equal to the 10V minus the drop across the 10-ohm resistor. If we go further then there will be drop across one more 10-ohm resistor. But here we are not interested in the voltage after node A. If you start the loop from 20V voltage source up to node A then also you will get the same voltage. e.g 20V - (10) (0.5) = 15V. So, the point is no need to complete the loop here to find the voltage at node A. And you can start either from 10V voltage source or from the other end (20V voltage source), you will get the same result. I hope it will clear your doubt.

[@nilakanta2555]

Sir, In 10.33 minutes, why the independents voltage gets short circuited.

[@ALLABOUTELECTRONICS]

Since the terminal A and B is short circuited, so voltage across terminal A and B is zero. And therefore, voltage Vab is zero. So, that's why that dependent source gets short circuited.

[@nilakanta2555]

Sir, if the dependent source is current source in that case it will short circuited or open circuited?

[@ALLABOUTELECTRONICS]

@@nilakanta2555 If it is a current source then it will get open circuited. In this case, since it is a voltage source, so it is short-circuited.

[@nilakanta2555]

Thank you very much Sir

[@coster1983]

I think this guy should be an auctioneer. Where is the KZbin slow down button

[@sumitbisht4161]

A video for Norton's too!!!

[@debasishsau4323]

I did not understand (0.5÷2.5mA)=(500÷2.5) We know that 1mA=1000A..how is it possible?

[@ALLABOUTELECTRONICS]

0.5 / 2.5 mA = 0.5 / (2.5 X 10^-3) = 0.5 x 10^3 /2.5 = 500/2.5.

[@dasuntharaka7162]

15V what youre doing?