Circuits I: RLC Circuit Response

This video discusses how we analyze RLC circuits by way of second order differential equations. I discuss both parallel and series RLC configurations, looking primarily at Natural Response, but also touching on Step Response.

[@jimkim6743]

This guy is a genius, writing backwards the whole time while teaching dats crazy

[@OfSilverMice]

I'm not sure if this is a joke, but he isn't writing backwards. In the original video, the writing would appear backwards for the camera and forwards for him, and then it is mirrored in editing. Notice that his UC Davis polo is backwards, and that he is writing with his left arm (he uses his right arm in previous videos with a whiteboard). Of course, he may still be a genius for explaining the material so clearly! :)

[@denisl2760]

Actually that's a pretty clever technique, he might be genius for coming up with that one.

[@RexGalilae]

Denis Lipatnikov Many people actually do it so yeah =P

[@PrAjYoTSUPAL]

Jim Kim he flip's the video layer

[@zippySquirrelface]

Check out math BFF! she does it too

[@observer4322]

There's so many comments like this on youtube, but I have to make a statement. Thank you so much for everything about this video. You are a wonderful person for making this contribution to society. My college is unequipped to teach circuits, but they have to offer the class. The teacher is not great, there aren't any tutoring services available, and if I fail to learn this material I will not be able to transfer to university next semester. So much is riding on understanding this. The stress is unbearable. This video is honestly helping me out of a very dark place right now. Thank you.

[@ThePhDEngineer]

Glad to be of some help! Keep at it! You will get through this!

[@lennyatomz8389]

Thank you, Dr. Montgomery! This RLC explanation is, by far, the clearest and most concise I have ever seen/heard. I have been struggling with this topic quite a bit this semester, but I now feel much more confident moving forward thanks to your work. Thank you again, sir!

[@altuber99_athlete]

Man, this video was extremely perfect. Great. Love you.

[@cristianaguilar8686]

this video is actually gold. Perfect explanations

[@Prince-lt6ct]

WoW. I've spent weeks trying to understand this but I couldn't and with less than 40 minutes now I can have confidence to write my exams. Thanks so much!! Subscribed

[@achi965]

Amazing thank you so much, couldn't find a better explanation anywhere

[@prasadnithianandam7614]

This chapter is the death of me, but thank you, you helped.

[@mayito714]

This is strictly differential equations based on the characteristic equation.

[@RexGalilae]

Mack Lack Thing is, in India, the calculus involved in Physics are always a year ahead of the calculus they teach in math, which involves diluting and overcomplicating one small part of math every year instead of moving forward to another topic. Good thing I learnt upto Fourier and Laplace transforms before I joined college since I was so crazy about Physics and Calculus back then.

[@goahead3654]

I know...I agree with u on that..

[@gideonilm4983]

just perfect. Loved your video, man. You saved my skin.

[@darinquintana6215]

so helpful. I can't stress it enough. you taught me what my paid college professor could not.

[@muhammadzohaibhassan6514]

Sir you r gr8 d way of your teaching is just " Fab " which helps alot during the studies. TQ

[@JeffReams]

This was one of the best lectures on RLC circuit response I've found. Well done ... thanks.

[@ThePhDEngineer]

Glad it was helpful!

[@xavierbolivar9549]

Thank you Dr. Montgomery, textbooks are great when you remember the pre-reqs. Unfortunately I forgot all of that and having a walkthrough of the differential equations part was a great help. Cheers!

[@ThePhDEngineer]

Glad it was helpful!

[@fun315]

Well descriptive, thank you so much.

[@mohsankayani]

retweeted , liked and subscribed as a token of my gratidude ! thank you very much sir!

[@brunofonseca9686]

Thank you so much! Greetings from Brazil

[@alexgomes9680]

Thank you! Starting my research tomorrow and this video helped brush off my knowledge.

[@ThePhDEngineer]

You're welcome!

[@electronicsworld8709]

Thank u very much sir.Also i like your way of delievering knowledge....

[@truepanda9205]

Excellent video, thank you so much.

[@satishbabu2007]

Sir.., Thank you very much, it is very interesting and really helpful to me.

[@zuhairalsaffar7001]

Sir you have given us a treasure of information about the RLC natural respons to much thanks for you 😊 😀

[@ThePhDEngineer]

So nice of you!

[@Swabey89]

Great video, thank you very much

[@another-learner8677]

excellent lecture. Our professor uses this method for this chapter which is different from the textbook's method. I've been searching for a lecture like this for a long time.

[@ThePhDEngineer]

Excellent!

[@fozsunar]

I saw couple of videos on youtube about this RLC topic but i can guaranteed that you are the best.I don.t need to go college to learn this anymore thanks to this videos thank you

[@ThePhDEngineer]

+fatih özsunar I'm not sure this will completely replace going to college, but glad you are able to learn a bit from it!

[@TheFootbaldd]

+Dr. Montgomery With the way education is going, it is just a matter of time before amazon ed opens up. Many institutions are setting themselves up to being the next blockbuster. At least in regards to many bachelors programs. When you go to fully online programs where lessons, homework, and test are delivered without direct manual instruction; yet the content delivery severely lags open source content. I can see the appeal for an instructor, but the writing is on the wall. It is just a matter of time before the accreditation system shifts to reflect the inefficiencies of today secondary education system. This, however, will play less of a role in the hands on, technical fields that are largely underemphasized. Welcome to the world of tomorrow.

[@ThePhDEngineer]

+TheFootbaldd Yeah...I'm not so sure. Fully online instruction may work for some students (those who are more self-motivated), but I think many students still need the more-personal, in the flesh, kind of experience. Look at MOOCs (massive open online courses)...their completion rates are terrible, because, as with many things in life, many of get a burst of motivation, but then move onto other things we become more interested in. Plus, sitting at home watching someone go through endless PowerPoint slides can be near some form of "cruel and unusual punishment." The other side of this is that, like it or not, many employers do still care about where you get your degree from. At least those in the engineering disciplines.

[@TheFootbaldd]

I certainly agree that brick and mortar classes in involved degrees are beneficial, but coming back to school I have found many of the programs have been offloaded to the ether. I am a strong supporter of traditional education, and free response evaluation. The program I am in now has gone the way of electronic means, and if I had known that before starting, I wouldn't have gone there. My point being that when you eliminate the classroom in essence, and others follow suit, institutions are ensuring their own demise as they cannot compete with more efficient and much cheaper alternatives. The limiting factor there is accreditation. When you turn instructors into forum moderators, you will find that there are companies much more experienced, who can eliminate the massive overhead experienced. The value of the institution is lost, and there are others who can provide better services for a fraction of the cost. That is not even mentioning the freely available content, such as the excellent videos you are producing.

[@TheFootbaldd]

I totally agree, spending the better part of 12 hours a day, by myself, on a laptop is excruciatingly dull. It is debatably worse than logging tac hours for Rickover; however, when schools take precedence to extracurriculars over a reasonable decade old gpa (3.2) and the experience of controlling a tin can with a hot rock around the world, your options are limited when trying to get a piece of paper.

[@vinaydesai9038]

video is superb sir, great explanation. sir please explain what exactly angular response and neper response with the help of transient waveform

[@askinc102]

thanks a lot....this really helped me

[@hispanic_panic7762]

Your videos are awesome!!, there very well done and detailed. Theve answered a lot of my questions. Do you think you could do some Laplace transform with RLC circuits videos in the future.

[@waqaryounis4387]

it helped a lot thank you sir hats off

[@user-zx9xi4rl7r]

thank you! it helped a lot!!!!!!!

[@hajeralmahri2404]

Thank you so much!!!!!!!!!!!!!!!!!!!!

[@PersianRamin]

thank you sooo much for this veery very helpful video sir!

[@ThePhDEngineer]

Most welcome!

[@ronschmith2901]

If you got lost at 13:12, he skipped finding dv/dt and d2v/dt2 which puts Ase^(st) in each term then multiply both sides by 1/Ase^(st) which leaves just s^2 +s/(RC) +1/(LC)=0

[@sourav79345]

very good .... thanks

[@muradshirinli710]

Which circuıt do the formulas you wrote down at the 34 minute belong to? Series or Parallel?

[@mariasolf2967]

GRACIAS, ME SIRVIÓ MUCHO.

[@ThePhDEngineer]

De Nada!

[@hadiabbas3083]

What a excellent lecture❤

[@ThePhDEngineer]

Thanks!

[@alias6676]

it would be nice to have a version of this using the symbolic method. No more differential equations, just complex algebraic, which is arguably way easier and faster to handle

[@jacobmonks3722]

How would you find the characteristic equation for the series if the value on the right side is nonzero?

[@OnlyOne1Dee]

This man his a real Doctor, wow do explanation sir

[@ThePhDEngineer]

Glad it helped!

[@moradkou6126]

Helped me, but dude WTF is that with the board?! For this alone you deserve a subscription =)

[@truptipatil5316]

We can use integrating factor method to find roots easily

[@mokarrommolla5820]

As you found the characteristic equation of parallel and series circuit. If there are more than 1 R, C, and L how are you gonna write the characteristic equation? Thanks

[@berniespy]

Great video! Explained very concisely and the visuals helped a lot. Only bit of feedback I would offer is giving a worked example with a more complicated circuit that needs to be reduced to series/ parallel form - maybe save that for another video.

[@ThePhDEngineer]

Thanks for the feedback -- it's been a while since I did these videos, but if I ever re-start them, I will keep this in mind!

[@bitsurfer0101]

Are you using transform analysis to come up with the Characteristic Equation?

[@abdelrahmanabuhaiba7083]

thanks a lot

[@homerodaniel_007]

33:15 Why are you doing the KCL in terms of the derivative of current ? is not C(dv/dt) for capacitor current and 1/L integral of v dt for inductors current?

Solved! He's getting the symmetry of the video.

[@hasneansafaa]

Hi dr. If i have a 12v dc and i want to ractfier the hartz for 15maga hartz can i do it

[@OnlyOne1Dee]

Thank you sir, this explanation is the best

[@ThePhDEngineer]

Glad it helped!

[@OnlyOne1Dee]

@@ThePhDEngineer May God almighty bless you more sir

[@AdaamTube]

Awesome

[@mikeymikemike275]

DUDE! You rock Dr Montgomery!!!!

[@ThePhDEngineer]

+sirspamsalot2 Well, thank you very much Sir Spams-A-Lot!

[@parkerflop]

He is Sir Spams a Lot the second.

[@ThePhDEngineer]

+Mustafa M My apologies...can I be Sir Spams a Lot the Third?

[@parkerflop]

+Dr. Montgomery lolol

[@abduljavedsadat1880]

Sir can you explain the in more details the step response that how we get the voltage terms in the equation ?

[@henidhia8028]

الله اكبر الحمد لله لاحول و لا قوة الا بالله اللهم صل و سلم و بارك على سيدنا و نبينا محمد

[@ThePhDEngineer]

Right on!

[@jorgerocha6912]

You have the best videos in the transient analysis I've seen but it seems that you stopped making videos since almost a year ago, I hope everything is ok and you make more soon.

[@ThePhDEngineer]

+Jorge Rocha Hi Jorge...yes I am doing well, but no longer teaching at UC Davis. I am teaching part-time at the University of New Mexico, but teaching solar cells now! Perhaps one day I'll get around to making some solar cell related videos.

[@Dragon30ficationXD]

Are the responses the same for the current?

[@indus7841]

Thanks Doc.

[@ThePhDEngineer]

You are welcome!

[@wise1330]

In applying KVL to series RLC circuit (at7:42), why is I(sub 0) not appearing in the equation?

[@thiagocavalcante2366]

Hi Dr. Montgomery, Are you sure it is v(t)=D1*t*exp(-alpha*t)+D2*exp(-alpha*t)? instead of "-alpha" is the solution of the characteristics equation? being v(t)=D1*t*exp(s*t)+D2*exp(s*t). Thanks!

[@MadJDMTurboBoost]

I think ur right

[@Dragon30ficationXD]

Yes my textbook says so aswell

[@TheFootbaldd]

Great video sir. Besides the homogenous portion of the basic bandpass and rejection filters, this got me thinking about some of the higher level analog filter networks. Having just touched the surface in applied audio DSP systems I find it amazing how they were able to design the abstraction that can emulate virtually every filter combination with high level graphical interfaces. Are you familiar with the bi-quadratics that model filters in DSP? It seems like prior PFM (acronym for pure... magic) is beginning to really make sense. Keep it up, being back in school, I find that more then a few of my instructors are severely lacking in delivery, if at all.

[@ThePhDEngineer]

+TheFootbaldd Howdy...I'm not too familiar with DSP systems, as circuits is not really my specialty (as for my research). But, I'm glad to hear some pieces are starting to come together for you. I appreciate the feedback on delivery...as you can probably surmise, I was a student not long ago myself, so I have tried to take all the bad examples I saw...and do the opposite!

[@TheFootbaldd]

Good to hear, I've been a student in different manners for the better part of a decade for what it is worth; but most of my research is on my own volition in regards to applied projects for the fun of it. With the digital signal processing systems that I am familiar with, you can directly enter what they call bi-quadratic functions. These functions can emulate everything from first order filters, to notch filters, to butter-worth filters... etc, and they also allow you to overlay filters. I haven't had the time lately to really delve into it, but I am starting to assume that the functions are merely the coefficients for differential equations. I have also been playing with building transmission line acoustic enclosures, and a lot of the modeling uses electrical reactive circuits. Anyways thanks for the reply and I hope you keep it up. I believe it was Einstein that said, if you can't explain something to a child, then you don't understand it. Much of learning is the ability to effectively communicate.

[@noblehazards9713]

i really don't understand how he got those roots for the characteristic equations, i tried deriving them myself and could not get it no matter how many times i tried

[@dalenassar9152]

I don't understand why the integral uses d(tau) at about timestamp 8:02 instead of dt. Can anyone help?

[@chrisnardi8594]

well done

[@ThePhDEngineer]

Thanks!

[@YafetKubrom15]

This video was very helpful. I appreciate the explanation. I was slightly annoyed by the squeaky noise of the marker but nonetheless, I understand the material so I cant complain.

[@ThePhDEngineer]

+Yafet Kubrom I'm glad you found it helpful...apologies for the squeaky markers!

[@MrPabloguida]

Why at minute 8:50 the derivative of iR was Rdi/dt? I tought it would be iRdi/dt.

[@noahauman]

How would one get in contact with such a knowledgeable individual? I have so many questions.

[@ThePhDEngineer]

Connect with me here: www.thephdengineer.com/join

[@dalenassar9152]

Near the start, you added the term Io in case of an initial current through the inductor. Why didn't you add the term Vo in case of an initial voltage across the capacitor? THANKS FOR THE GREAT VIDEO!

[@darshilkaneria2416]

If you look at the series case, he did add the V0 term. In the first case, you do not need to add V0 because you are dealing with currents through the elements while deriving the final equation, not the voltage across them.

[@icky7a]

why is I(0) a constant and V/R not a constant?

[@simransingh1885]

Why is the direction of Ic downward? Can somebody help me with that

[@beckham8058]

Write directly on the screen and record at the same time How did you do it, can you tell me?please

[@ThePhDEngineer]

Magic...

[@RexGalilae]

Can someone explain how he got the first term of the critically damped circuit's solution at 28:16 please? AFAIK, when there's only one root to the characteristic equation, there should only be a single term in the solution

[@justinb9032]

Rex Galilae the root is repeated twice and to have 2 unique solutions one must be linearly independent of the other which is why there is a t attached to it

[@MizanurRahman-ei4wr]

Immediately can i get a solve of a problem.. And how can i get it

[@ThePhDEngineer]

No...

[@bader4202]

HI I noticed that in natural response it was d^2v/dt^2 + 1/rc dv/dt +1/lc=0 when you add a I source to the same cct it became d^2i/dt^2+...... do i have to situations or you did by mistake thank it was very helpful

[@ThePhDEngineer]

Actually those two different solutions are for the two different cases: parallel RLC vs series RLC

[@jamesayento1321]

When you add a source in the parallel rlc circuit why is it that your kcl equation is in terms of iLdt instead of Vdt?

[@christiancastillo3857]

I'm more impressed on how he writes backwards

[@ThePhDEngineer]

Magic!

[@yasirmahana6471]

thank you dr ,montgomery i dont speak english but i understand for step solution thank very good iam sory eror in word

[@yasirmahana6471]

@@ElectricalEngineeringAcademy thank you

[@ThePhDEngineer]

Thank you!

[@faifai4]

Can someone explain to me how is the camera set up? I know it's impractical to learn how to write Mirrored words (left to right). What camera trick is this?

[@faifai4]

+PussyGalore The only thing I could think of is that they are using some sort of a smart board\.

[@ThePhDEngineer]

+PussyGalore Magic....just pure black magic. Actually, it's a pretty basic set up. I'm standing on one side of the glass, camera is facing me from the other side. The raw video is actually backwards, so we just mirror the video in editing software, which gives the impression that I must be writing backwards!

[@edgerrr]

+Dr. Montgomery ... Before I read the comments, I thought you WERE writing backwards and making it look easy. Now I see that "UC DAVIS" is backwards on your shirt. Nice overview lesson, thank you!

[@zviez]

+Dr. Montgomery menas that you are right-handed?

[@jasminesaad1581]

Why does his quadratic formula not have the -4*a*c? or the division of 2 of the square root?

[@dalenassar9152]

I am in the middle of the video (1st viewing), and have paused to try to justify EXACTLY what you are asking...I will now work out that quadratic and try to justify what he has written up to 17:00 ... If I find out what is going on, I will post back here.

[@dalenassar9152]

OK, he just multiplied the denominator by 1/2 instead of dividing by 2. Under the radical, all was multiplied by 1/4 (which is the square of 1/2) and cancelled the constants. I think he wanted the 1/LC to stand out. sqrt(1/LC) = frequency.

[@dalenassar9152]

That should read "NUMERATOR", sorry...

[@charlieoocharlie9466]

@@dalenassar9152 hi

[@jinshikami7525]

Need help on an EE problem? Track down: 'Circuit Solver' by Phasor Systems on Google Play.

[@saddaamhusssain8571]

cap herehe just draws then uploads the video after mirroring it*flies away*

[@amjad6361]

may Allah bless you, thanks a lot

[@ElectricalEngineeringAcademy]

kzbin.info/door/tgu8i2WD-WSZuOuI9ZJukQ

[@ThePhDEngineer]

Thanks!

[@randomcarrot7970]

31:44

[@shivaanem]

I love you

[@idhyakavin2892]

Shiva haiii how are you

[@idhyakavin2892]

Reply to me

[@shivaanem]

Who are you? Lol

[@ThePhDEngineer]

Love you too!

[@genar8202]

10:50

[@daisy-fb5jc]

Save me hours of studying for a circuit final that is 4 hours later...

[@ThePhDEngineer]

Let's gooooO!

[@Kuzeyman09]

Dont worry boys. Engineer gaming is here

[@jinshikami7525]

Need help on an EE problem? Arrive at: 'Circuit Solver' by Phasor Systems on Google Play.

[@HaNa-cy5eo]

svp lèq diffèrentielle en ub dans un circuit RLC !!

[@jinshikami7525]

Ohm my gosh you should try this application! Look up: 'Circuit Solver' on Google Play.

[@paritoshpandey5103]

How is he writing backwards🤔🤔🤔🤔

[@Daniel-rm6hj]

Did you just learn to write backwards or are you using some mind blown mirror setup?

[@ThePhDEngineer]

Nifty post-processing trick...I cannot actually write backwards!

[@pratikahir148]

He fucking explain what's in the book.

[@ThePhDEngineer]

Read a book or watch a video - your choice!

[@eccleziassenat3262]

ucf student here;

[@ElectricalEngineeringAcademy]

kzbin.info/door/tgu8i2WD-WSZuOuI9ZJukQ

[@ThePhDEngineer]

Go UCF!

[@stovegamesgames6917]

jfc all this for capacitors and inductors

[@thesolidfox9225]

اللي ما فهم شي من زيدوري وجا هنا لايك

[@ThePhDEngineer]

Right on!

[@kilany10]

i'd rather you attempt them not just copy

[@salmamaazouz5632]

do you speak arabic

[@berniespy]

yep he clearly speaks arabic

[@MarkMcDaniel]

I wish he'd have focus on each (parallel and series) circuit independently. For we students, it's hard enough to follow without the double-dutch teaching crap this video exhibits.

[@ElectricalEngineeringAcademy]

kzbin.info/door/tgu8i2WD-WSZuOuI9ZJukQ

[@mohammedelyarroumi2066]

Mouselsel turk t Fi dakhil

[@mohammedelyarroumi2066]

مسلسلات تركية

[@user-rz2fs3xw7d]

Mohammed El yarroumi what you mean? ??

[@muhammadfaizan2232]

Jee oye, 1 meethi chummi mera best friend k liye

[@ThePhDEngineer]

Thanks!

[@tunteerasujaritpong7757]

Hello professor, I'm student teachers in Thailand. I like you to teaching your video clips. I want to made a video teaching same you. This instruction media to keep children interested in learning more. Thanks to that I have come across this clip. help me or guide me for made clip ,Please 🤓🙏🏻thank you very much.

[@user-rz2fs3xw7d]

tuntun yong this video for middle level clever students ...do you accept with me???

[@tunteerasujaritpong7757]

Engineer Hawraa Yes, I'm interested for children. You're a teacher ?🙂

[@user-rz2fs3xw7d]

!No,I"m engineer.....Ithink you are love your pupil

[@tunteerasujaritpong7757]

Engineer Hawraa yes 😍So thank you you help me ,please Now I'm teaching Vocational Education (electrical power department)

[@user-rz2fs3xw7d]

how can i help you??h

[@scottgreen3807]

I have a degree in electronics and years of experience with it. This stuff is of none real world use because other than simple power supply circuits or supply circuit choking or filtering it’s of little practice use usually. Say complex ac circuit analysis for some potential real world use. It needs an alternating current usage to be useful and that’s still a lot more complex than this boastful calculus confusion. Inductors and capacitors have little practice usage for this talk, but it’s good warmup for further “stuff”. It sure is interesting calculus implementation and other stuff but why bother with this stuff when it’s hardly real world in application. You torture your student with this.

[@ThePhDEngineer]

Thanks!