While Dave hasn't made such a course, there are quite a few here on RU-vid. Since I haven't had much official (i.e., University-level) EE training (I'm an ME!), I looked and stumbled across the "Science and Math" channel where a guy who was a NASA EE teaches several free EE courses.
Thank you, Dave , for these insightful instruction videos. I have been out of the AC power field for many years. It is good to have a refresher about complex numbers. I have been doing digital electronics and computers fro 20 plus years. In the US Navy, I worked on AC generators and motors, not really knowing this aspect expect for private study. Thanks again!
I love the fundamentals and tutorials content the most! Teardowns, debunks, and mailbag are fine, too, but this is the stuff that I revisit, benefit from, and recommend to my colleagues.
Another great tutorial, vital for both the new players and some old hands for a basics brush up over a coffee. Don't be disheartened by a few bad comments, your channel has something for everyone, after fifty years in the industry I still sometimes pick up a useful nugget from your content. Remember, you cannot please all the people all the time but I for one have watched your channel(s) for years, thanks.
Another way to express "CIVIL" as I was taught in college: "ELI" the "ICE" man . . . E leads I in L inductive reactance, and I leads E in C capacitive reactance. Since then, "V" has pretty much replaced "E" in electronics nomenclature . . . but still useful!
Thanks Dave, I love this content. Your clear and simple explanation really helped me bridge the gap between vector math (which I'm comfortable with) and complex numbers. Looking forward to more videos in this series.
Loving this content, short punchy and gives you the info you need, as opposed to my university course (graduated some many years ago now) which padded this topic out to multiple semesters...
Next week's program for me and my students! Good overview! If I want to be a bit picky than you should have indicated the phase in your sine-graph in the beginning between similar points om both waves, not between the falling slope of the blue and the rising slope of the red curve. Actually I never bothered to figure out R/P and P/R on the calculator, but always used (and taught) the "long" way using abs(Z) and arctan(Im/Re) - but now I will show my students what their calculators can do!
20:56 actually it doesn't matter if you use rms-voltages, amplitudes or peak-to-peak voltages, as long as you stick one of these for the full calculation.
Great video, Dave. Of the many ways to do AC analysis you nailed the most useful. I especially like your explanation of using polar for multiply/divide and rectangular for add/subtract, and the RP calc functions to convert. Details I've long forgotten since taught in the 70's and done on my HP45 at WPI.
Crikey- I never knew there was still so much to learn and, you make it easy to understand - Thanks Dave. I'm going to be binge watching your tutorials now.
Very cool! Complex numbers are a mathematical abstraction that model the real world... Very useful for Science and Engineering ! Remember j is for Engineers.
OMG! Why couldn't my math teacher explain it like this?!😳🤓 The past 25ish years would have bee far easier if my Algebra teacher had explained it like this! Haha 😳 Thank you for putting this series out! It has answered a lot of questions I had on why A/C does what it does! 🤓
Also, would it be possible for a little followup with some practical examples? I thank you so much for all of the learnin' you've given me over the years!😜 Thank you! 🙏👍🤓
After this Dave.... It is a must that you supply an ac voltage to an RL-circuit and measure phase and amplitude of the current and then compare to the calculated values. 😀
Saw part 2 in my feed... missed part 3 somehow.. must have been busy. Lots of value in these tutorials to watch when I am able to focus on the video (as opposed to the 90% videos in the background while I work situation) Kind of surprising how low the view count gets when class is in session. Another possible angle - Many subscribers that would have watched this video may have already taken circuit theory :)
Got your note about the seperate channel. From here on, as soon as I get the bell notification i run your video, even if i have to come back and watch it later ;) shove it YT algorithm
Fantastic video, really liking the AC content, even as a refresher course for me. One question, however: at 15:12 you call the two components of the Polar form "Real" and "Phase Component". I think calling it Real can confuse some people because in Cartesian form, the Real part of the complex number is typically the x-axis, as you explained earlier in the video. Would it be better to call it "Magnitude" in this case?
Obligatory dad joke: These phase components will always be Greek to me. Thank you for continuing this series, Dave. This is fundamental to analog electronics (which obviously includes audio). One thing that has always mystified me is exactly *why* there is a phase shift through a capacitor or inductor, and how voltage could possibly *lead* current through an inductor. Adding the complex dimension, it's actually starting to make sense.
After 10 or so years of watching this channel, I have never once left a comment. And the reason is simple. I enjoy Dave's content. The creator of this channel doesn't owe me anything and I have nothing interesting enough to contribute via a comment, so I don't. This message is for all the people that just can't help themselves but offer unsolicited advice on the types of output they feel there not getting enough of. You get what your given, and if you don't like it. Take your bat and ball and go home.
Pulled out my trusty decades-old TI-83 Plus, and had an existential crisis... it didn't have the R/P conversion buttons!! 😱 Crisis averted -- TI buried the functions behind the "Math" button (labeled ">Rect" and ">Polar" under the "CPX" tab). Whew. 😅 Oh, and thanks for motivating me to check the calculator... the batteries leaked. 🙄
I've had all these phase-shifting calculations at school (i work with low and high voltage electrical distribution systems, so lots of three-phase stuff like generators, transformers and networks) , except the polar/rectangular conversion. I always knew there was some sort of method to make these calculations easier, but somehow (i know, schooling level, i don't have a degree, i'm not an engineer) it fell out of the scope. I wish i had this knowledge much earlier before...
Maybe I missed it, but I was expecting an explanation that i or j is the square root of negative one. It's been about 40 years since I had the class, but sometimes we had to multiply (a + jb) x (c + jd), and you had to deal with the square of j. Since j is the square root of negative one, the square of j is negative one, which is critical to getting the correct answers. Perhaps that is a bit deeper than this series of lessons was shooting for?
@@Asdayasman but that doesn't address the need to do multiplication when you are still dealing with variables. In my example above, (a + jb) x (c + jd), the result is (ac - bd) + j(bc + ad). I can't imagine trying to do this by converting this to polar notation.
@@SkyhawkSteve I would guess that Dave, being an incredibly well experienced professional in the field, understands that the need to do that is rare enough that it doesn't need to be included in an "AC Basics" class. Remember he's a practical engineer, not a theoretical scientist. You can measure a whole bunch of stuff and reify a variable easily enough.
@@SkyhawkSteve Sorry, I think you missed the part where I said Dave is a "well experienced professional in the field". I said nothing about the cesspit that is institutionalised education. 20% of the things they teach in universities are useless 80% of the time. The other 80% are useless 100% of the time. I don't care what's taught in the "first semester" - if Dave didn't see fit to explain it, it's not the sort of thing you need as a beginner.
I think complex numbers should be called compound numbers or multi-dimensional numbers. The complex name doesn't stand for complicated. Why i^2 = -1? Simply because i^2 = (0,1)*(0,1) = (-1,0)
Complex numbers in mathematics are commonly expressed using i,j and k as complex ones, not only i. Essentially the Z = X + i.Y is the same as writing Z = 1.X + i.Y - vector addition of two components, where the 1 and i are unit vectors on their respective axes, only in practice 1 is omitted by convention. In higher dimensions (e.g. quaternions) i,j,k are used as unit vectors on the three imaginary axes.
"Nothing imaginary about these numbers, they are very real" - haha, that was great! Catchphrase unlocked. 12:37 looks more like -5+j4 Again, complex is better than complicated! :D I like the CIVIL notation. Mnemotechnic to the rescue!
One correction Dave: On the diagram at 11:41, the whole diagram is the 'complex plane': a 'plane' is two dimensional. What you've labelled the 'complex plane' should be the 'imaginary axis' and the 'real plane' should be the 'real axis'. It's the real axis of the complex plane and the imaginary axis of the complex plane.
I've always wondered why complex numbers are used to describe vectors for AC power. There are other ways to do it. I suppose it is just more efficient?
For multiplying them, wouldn't it be easier to FOIL the two complex numbers rather than converting to polar (especially if you have only a basic calculator to hand)?
Nice video about the fundamentals of AC calculations. But I'd argue polar and rectangular conversion has lost alot of meaning today when your average scientific/school calculator can calculate complex numbers natively and you can just punch in the complex multiplication/division as is. In the cases where you aren't allowed to use a calculator (and those still exist in some courses), the difference between doing a division by extension with konjugated complex numbers isn't that much harder either since you need to solve a pythagoras for polar conversion as well, not to mention the arc function. Complex multiplaction is trivial anyway and a good idea to learn as a principle for vector calculus should you make it to up to field and wave theory in 3d spaces (paraphrasing, because I have no idea what it's called in English). Essentially you only get something out of it if you are only allowed to use an old scientific calaculator, which even during my time in uni 10 years ago was already becoming exceptionally rare. Either we weren't allowed to use a calculator at all, we were allowed to use a 4 banger or we could go all out with a scientific calculator (sometimes with a clause that it may not be capable of graphics and non-programable). By the way, I just noticed my stupid smartphone calculator doesn't even have polar rectangular conversion, at least I can't figure out where it may be. Weird choice to have hyperbolic functions but not simple conversions like that. PS: Also you drew a -5+j4 there. ;)
Hi Dave, Your videos are very informative. I've learned a lot. Just a small correction to something that might be confusing to some viewers. On the diagram where you show the two sine waves against time, shouldn't the phase difference be shown shifted to the left between the downward crossings of the two waves rather than between the downward crossing of one and the upward upward crossing of the other as shown? (I know this is nit picking)! Thanks.
Isnt RMS (root mean square) an effective value of waveform (square root of two times samller then peak-for sine wave only), you said its peak at the begging just wanted to meantion so people dont get confused (cca 1:50)
Hey Dave, thanks for the great videos as always!!! when you said two adding sinwave always results in another sinwave, do they need to have Sam frequency?
Thanks! So if that's the case, if someone makes a very clever device to mix different sinwaves, they could theoretically make any other signal shapes like square, sawtooth or even DC from mixing sinwave? And also the other way around, you should be able to remove and separate this hidden wave shapes from example of a square wave? I'm not sure if what I said makes sense at all!😵💫
You state "For addition and subtraction you need to use rectangular form. and for multiplication and division you need to use polar form". Is that strictly true? Can you not perform multiplication / division on complex numbers?
