Ohm's Law for AC Circuits with Resistors, Capacitors, and Inductors.

Рет қаралды 1,619

Күн бұрын

How to use Ohm's Law for AC Circuits where Resistors, Capacitors, and Inductors add phase shifts to voltage and current. We demonstrate phasor calculations which do include the phase, something not needed for DC circuits, and we do a demonstration of this using a RLC tuned circuit.
The online calculator used i the video is here:
calculators-ma...
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Пікірлер: 53

@transformateur9969 2 ай бұрын

Well done ! Extraordinary explanation! You would perfectly teach the operation of the mixer in a superheterodyne, which no one has done until now ! ❤❤❤

@ElectromagneticVideos 2 ай бұрын

Thanks you so much! Superhet mixer - definitely in the future. I do plan to do modulation/demodulation sometime and that all fits together.

@johanrheeder1640 2 ай бұрын

Great explanation, Good video, well done

@ElectromagneticVideos 2 ай бұрын

Thanks!

@zxcv835 2 ай бұрын

Very good explanation and great calculator tip for people with poor math background (like me).

@ElectromagneticVideos 2 ай бұрын

I REALLY appreciate your comment - I was really trying make the video useful for people without a background in complex math. I looked at a number of online calculators - the one I showed seemed to really be the easiest to use. I didn't point it out, but while the second line of results from the calculator gives the results in phasor (polar) form, the first line of results is in the form of 6.00 + 6.00i which conveniently is the phasor split into the real part (the first number = in phase current, real power etc) and imaginary part (the second number with the i at the end = the 90 out of phase part = the reactive power or current) which can also be useful.

@ThriftyToolShed 2 ай бұрын

Excellent video with great explanations. Thanks for sharing this knowledge. It brings back memories of one class in Tech school I had in the 90's. The class was really just Electrical Level 2. It never had this deep of topic listed for the class, but the older gentleman contracted to teach the class happen to be a retired NASA engineer and the more we asked the deeper he went across the black board. He was incredible. I was so amazed about how much he knew about vacuum tubes and electronics in general as well as XL and XC calculations with phase angles. I wish I could have retained even 10% of the knowledge he shared.

@ElectromagneticVideos 2 ай бұрын

Wow - wonderful that your classed asked him to go deeper - shows the quality of the people in the class. Probably pleased him too - nothing better than students that want to learn! Vacuum tubes - we no longer had that in our classes - transistors had fully taken over. Luckily I had experience with tubes from fixing old TVs when I was in high school (it was the old tube TVs that were giving out at that time) so I learned a lot about how they worked and have always liked tubes. Somewhere I have an old tube tester I will have to find and make a video about. I wonder how many people have even seen a tube tester!

@ThriftyToolShed 2 ай бұрын

@ElectromagneticVideos I wonder how many people know about tube testers as well. I never worked on many tubes personally. I have always been fascinated by what EEs did accomplish with them before solid state was invented. That one class touched on them because He did really enjoy sharing his past knowledge for sure. I did desire to work on TVs and monitors with CRTs, but I never learned a lot about them and only managed to fix a few with much simpler issues like bad switches and maybe a bad capacitor, but I never learned enough to replace flyback transformers etc. back then. I did desire to learn, but we did not have KZbin.😂

@ElectromagneticVideos 2 ай бұрын

@@ThriftyToolShed When you think about it, a color TV might have had a dozen tubes, each with two or three devices in the tube = ie a triode and diode, or two triodes etc. So say a color TV had two or three dozen elements of the functionality equivalent of a single semiconductor device. Today even the simplest analog op-amps have dozens of transistors and any microprocessor based system has millions to 10s of billions of transistors. Electronics people todays probably cant fathom being restricted to a handful of active devices. I'll have to find my old tube tester - it actually was a kit that was sold surplus because nobody was buying tube testers any more. I was so thrilled to have it - made fixing old TVs so much easier. Do you remeber the old table sized tube testers in drugstores? I was fascinated as a little kid watching my dad test a bunch of tubes every time the TV acted up. Lack of KZbin and information back then - what a struggle it was to get information. I still have databooks from Motorola, National Semiconductor etc obtained by wring a letter to each company - imagine that today! I would have been ecstatic to have the access to info we had today - although with all the distractions of messaging etc - would be have leaned as much?

@WOFFY-qc9te 2 ай бұрын

@@ThriftyToolShed Mr Carlson has just done a video on tube testers and Shango66 has a few he puts though their paces on on old RCA TV's, Glasslinger has a good collection of tubes and some videos of him making them, fascinating chap. David Tipton is a good watch for fault finding tube set. Best Jim's Radio Workshop, he is in Canada and although a slow video much can be learnt.

@ThriftyToolShed 2 ай бұрын

@ElectromagneticVideos The marvel of the first color TV's: I will never be able to wrap my head around it. Genius level to come up with such an amazingly complex solution for making the image on the screen in rows and using the 3 guns scanning across and controlled by the yoke by "magnetic deflection"? I am not even sure... Like you mentioned using the tubes and few components already available and making the custom CRTs. Down right magical to my brain. I am as fascinated with it as I am the early NASA engineering. The solutions they had to come up with to go where no one had yet gone. Sorry to deviate there, but similar in my mind of fascinating things. I will link a video below of an interview that Destin did on KZbin Channel- Smarter every day. It was so worth watching in case you haven't. He interviewed Luke Talley about the early rockets and I am so glad he captured the knowledge and memories from Luke in that video interview. I don't actually remember the tube testers in stores myself, but I do remember people talking about them. I did buy a used tube tester back 20 years or so ago and I eventually sold it on ebay for very little when I was moving years later. I wish I had kept it now. I may eventually see if I can find another one since I still want to learn more about them. I look forward to the next video! kzbin.info/www/bejne/Z5-veXyDZ66DiLssi=vnVeouDLmUDRiu-d

@miltonthecat2240 2 ай бұрын

For me, this was a great review of the basics. I have gotten into the perhaps bad habit of using LTSpice for just about everything, no matter how simple. But I would never advise anyone to skip learning the basics and jump to using LTSpice, or another simulation tool, without understanding what is going on "under the hood". (Of course, you can try dozens of circuit tweaks in the same amount of time as you could build a single hardware prototype circuit, so the temptation can be overwhelming.) The second half of AC circuit analysis is transient analysis; that might be a good topic for a future video, if you haven't covered it already. For example, if you suddenly connect an inductor directly across mains, what will the inrush current be? Will the inrush current be minimized if the inductor is connected at a zero crossing of the mains voltage waveform? The answer has always seemed counterintuitive to me.

@ElectromagneticVideos 2 ай бұрын

The basics - its funny - I had to come to grips with just doing phasor calculations in the video without really proving the underlying "why does it work". It never satisfying to have to say - just accept how to add, subtract, multiply and divide these things without the underlying stuff. So I have really been pondering if a transient analysis video is feasible . My current thinking is to maybe show some transients as you describe, and with a lot of hand waving, sort of explain it and give a sense of how to roughly estimate it. A more rigorous intro with math like Laplace transforms is probably beyond this sort of video. I actually mentioned transients in one of the takes I did of the end of the video wrap up segment, but didn't use that one because I felt it muddied would be more confusing than helpful.

@WOFFY-qc9te 2 ай бұрын

I agree a helpful refresher and a reminder of the significance of the notation I automatically punch in a calculator although not that often now. Very good tutorial.

@ElectromagneticVideos 2 ай бұрын

@WOFFY-qc9te Any idea what would be a good currently available calculator for this type of thing? I still use my 40 year old HP-15C but I'm sure there are more current ones better suited for the modern world ...

@WOFFY-qc9te 2 ай бұрын

@@ElectromagneticVideos Hello, Calculator, well I do not do much power calculation now, my calculator is an old TI scientific with the LED display, I did have an HP I think it had program cards that slotted in the sides. By habit I just pushed the same old buttons and recalled equations from the memory I suspect you are doing similar. App based calculators are in favour although not as quaint as a forty year calculator are probably much more useable. I just had a look at the price and yours his holding its value, keep the LCD away from heat or sun. The IEEE have a Multi-Utility Calculator Application and their site has many recourses. This student made this comment ; TI-89 Titanium, the TI-Nspire CXII CAS, and the HP PrimeThe TI-89 Ti looks like the most appealing of them all due to its cheap cost ($50-60, secondhand) and due to the amazing EE* PRO program it has. The program has everything I need for my studies. I did find you tutorial realigned my thinking and refreshed some dormant knowledge. The storm over the UK has passed and I need to cut up another fallen tree, only have ten left. Best

@ElectromagneticVideos 2 ай бұрын

@WOFFY-qc9te Sorry to hear about the storms! Thanks for the calculator info! Funny we are the same - using to e old calculators from way back, although mine has what was then new technology - a LCD display :)

@newmonengineering 2 ай бұрын

Good video as always! I appreciate the time you spend educating. Have you ever wound your own transformer? And if so would you possibly do a video with the math to calculate the turns needed on the primary side for a given a set wire size, core and voltage? If not thats ok too, I know not many people do such a thing. Thank you for the knowledge.

@ElectromagneticVideos 2 ай бұрын

Yes - as a kid! I just copied you comment to my list of thing for future videos. There is a 100 year old DIY book that has howtos for that and many other fascinating things if your interested. Look up "The Boy Electrician" and dont let the name put you off. It was in the school library when I was a kid - read it from cover to cover and was mesmerized by it even though it was already an antique back then. It widely available online (I think it was published before that date that copyrights start) so google it it your interested!

@russellslater4037 Ай бұрын

Fantastic explanation as usual, thank you. However, do we need to bring the ESR of a capacitor into the calculation, or is that always going to be so small as to be, effectively, ignorable?

@ElectromagneticVideos Ай бұрын

You do bring up an interesting point. The AC caps I tested all had existentially a pf of 0 and (equivalently) no real power consumption. So the ESR must have bee so relatively small compared to the current flowing that it was negligible. The 5 little caps I used in series with the toroid were ceramic which typically have low ESR. Ones I used in other videos were poly film caps if I remember correctly - also relatively low ESR. (ESR = Equivalent Series Resistance for anyone wondering what we are talking about). Its usually the electrolytics that have bad ESRs particularly at higher frequencies, although in this context I would suspect they would show little power loss as well (assuming we put two opposite in series with reverse diodes to keep from blowing them up :) Might be an interesting test.

@retrozmachine1189 2 ай бұрын

As soon as you said 'you'll just have to imagine that says -90' earlier on in the video, I thought 'imaginary numbers coming this way soon'. Maths was not my strong point in high school but enough of it did stick.

@ElectromagneticVideos 2 ай бұрын

That "imaginary" number was only in my head :)

@bulbx1273 2 ай бұрын

Phases are really important in electro acoustic...

@ElectromagneticVideos 2 ай бұрын

Yes! You can really hear it when studio mics are out of phase or when one stereo speaker has its polarity reversed.

@bulbx1273 2 ай бұрын

@@ElectromagneticVideos Yes and at home when you try to calibrate a subwoofer, you can cancel basses instead of increase them when out of phase...

@ElectromagneticVideos 2 ай бұрын

@@bulbx1273 That must a a "why are the low frequencies so silent" type of experience!

@bulbx1273 2 ай бұрын

@@ElectromagneticVideos Yes, do it !

@ThinklikeTesla 2 ай бұрын

Parallel LC is pretty neat too

@ElectromagneticVideos Ай бұрын

Yes! Tuned circuits were getting a bit off topic so maybe series and parallel LC in a future video.

@ThinklikeTesla Ай бұрын

@@ElectromagneticVideos Even just computing the parallel resistance (impedance) formula on phasors is pretty cool.

@ElectromagneticVideos Ай бұрын

@@ThinklikeTesla Your right - maybe a short video just on that!

@The_Real_Grand_Nagus 2 ай бұрын

Great video as usual. I was just wondering about this since I saw your other video about power factor. I find AC a little harder to track than DC.

@ElectromagneticVideos 2 ай бұрын

It is a bit trickier! I will be doing one more video on power factor itself, including not only the nice classical linear power factor we have talked bout in these videos, but also the horrible spiky current PF from electronic powers supplies and which plagues our power grid these days.

@MrWaalkman 2 ай бұрын

I always think of Pi as "113355" (specifically 355/113). It's correct to six places to the right of the decimal point. Close enough for anything that I will do, and I don't have to find the darn Pi key on a calculator that I am not all that familiar with (which can be interpreted as anything other than a HP-15C).

@ElectromagneticVideos 2 ай бұрын

Thats an interesting memory tool that I had never heard of! Somehow after using it so many times. 3.14159 is in my head - strange - I am really poor at remembering numbers but I guess I have used it so often! HP-15C : I have one on my desk in front of me right now! Bought it in second year university when they had just come out. Best thing ever for anyone in EE, Physics or math!

@MrWaalkman 2 ай бұрын

@@ElectromagneticVideos Definitely pointless, but fun. Have you seen the HP-15C CE? (collector's Edition) I have it, and the not-so-great Limited Edition (don't bother if you don't have an LE). The CE is really nice. I still have my 15C from college, but the CE rocks.

@ElectromagneticVideos Ай бұрын

@@MrWaalkman I know of them but have never actually seen one in real life. Truth is, for a lot of calculation stuff there days I use either spreadsheets or matlab/octave because it makes it much easier to investigate how changing one number/property wither retyping the calculation. I use the 15C just for quick short calculations.

@MrWaalkman Ай бұрын

@@ElectromagneticVideos I'm (among other things) a calculator nerd. Not a math geek, I've always struggled with math. Thank goodness that I was an Controls Engineer where math was almost never used outside of calculating my overtime. :) It's the programming capability of calculators that I find fascinating. The limitations of the hardware at the time leading to (hopefully) clever ways of packing the last little bit of functionality in something with a mere handful of bytes of storage is amazing. I was too old for the cheap calculators that you see in high school these days, and too poor to buy one at the time (well above the price of a used car), so I usually made do with the tables in the back of the math books. Slide rules are also cool. I still have mine from high school. :) So I'll grab a calculator before I use anything else. And I'm happy that I am not alone, my Mechanical Engineer friends at the company that I do consulting for (AKA "The Arts and Crafts" engineers) almost all have a calculator sitting within easy reach.

@ElectromagneticVideos Ай бұрын

@@MrWaalkman A calculator nerd - how cool! You so right about how what a challenge it must have been to include every little bit of functionality and particularity programming in those early calculators. I remember programming a few things into them - in particular the quadratic equation which came up often. I think I also programmerd in some matrix functions, and a decimal to binary conversion which the 15C lacked but the 16C had. Those of us in the EE/CE program really could have used the 16C functionality but having two calculators was too expensive for us students. We also did slide rules in high school - but more as a math example of logs/exponentials since calculators were already common. I wonder ho many people know what a slide rule is today?

@carolmartin7042 14 күн бұрын

Thanks

@ElectromagneticVideos 14 күн бұрын

Yuur welcome!

@bigguyprepper 2 ай бұрын

How different does the math work out if your L,C, and R were in parallel instead of series? Also, do be very interested in the math behind why you add in Cartesian and multiply in polar

@ElectromagneticVideos 2 ай бұрын

The DC rule for a bunch of parallel resistors is 1/Rtotal =1/R1 +1/R2+1/R3 ... You can do the same with AC using phasors in the calculation. Do all of that and assuming the L and C are equal and opposite as in our example, they cancel and the parallel impedance becomes just R . If there was no R in the circuit, just L and C the combined impedance of LC becomes infinite. Multiply in polar, add in Cartesian? If you use the Cartesian coordinates as complex numbers (which they are here) with the second number in the pair being the imaginary part, you can do all adding, subtracting, multiplying, and dividing in complex numbers (where i *i = -1). The reason for doing multiplication and division in polar form is that at least to me its a bit more understandable in the sense that excluding the angle, its the same as real number multiplication and division, and its also easier to follow what happens with the angles. As for the underlying math, it would really be an explanation of complex number math because thats what all of this actually is. I would be pleased to do a video on it if there was enough interest in it, but I'm not sure there would be. IF OTHERS WOULD LIKE A VIDEO ON COMPLEX MATH, let me know by commenting below! Hope that helps!