EEVblog 1401 - DC Power, Efficiency, & Maximum Power Transfer Theory

Dave closes out the basic DC circuit series with DC Power, Efficiency, & Maximum Power Transfer Theory tutorial. Includes Ohm's law refresher.

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#ElectronicsCreators #Tutorial #DC

[flymypg]

I must have passed a quiz on Power Transfer Law in my first circuits class, then forgot it. When I got to RF transmission lines and impedance matching I finally understood it intuitively, and was surprised to learn it applied everywhere. Just goes to show that some "fundamentals" may need to be taught more than once, and from more than one perspective. Ohm's Law, in all its many forms, RULES!

[ChristieNel]

I don't know why kids go to school anymore when they have Dave. Honestly.

[FractalDynamics]

I love how the calculator is swapped out every couple of cuts, nice easter egg.

[excavatoree]

Dave's subtitle reminded me of something I read in a car forum. These guys were generally against Harley Davidson motorcycles, because they believed they were old technology, and inefficient. (not much mechanical energy out for the chemical energy one puts in. I won't get into THAT argument.) One person said "What do you mean? A Harley is almost 100 percent efficient..." After some incredulous comments, he finished "...at converting chemical energy into noise."

[LittleRainGames]

Glad you brought back fundamentals.
I was getting bored of dumpster teardowns.

[piconano]

All of trigonometry is based on one "mother of all formulas".
Sin(x)^2 + Cos(x)^2 = 1
All other trig formulas could be derived from it.
In electronics, Ohm's law rules.

[mattlambermon]

17:14 Maximum Power Point Tracking, a great way to think of this is one that we have all learnt intuitively from childhood with bicycle gears. Too low and your legs almost free spin on the pedals with little forwards movement, Too high and you feel your legs burn as you heave on the pedals, again with little movement. But when you use MPPT, starting in low gear to take off, click up gears as you accelerate to higher and higher speeds, you "ride" that peak efficiency, *Transducing* the most chemical potential energy into kinetic energy, with the least "wasted" energy, (~2000W Gross) Its like having a bar heater in each Feels like it to :-D

[mrmobodies]

10:49 probably learned that in
school....Learn't nothing like this in school they didn't show me much apart from the material and test questions from a water down narrow changing curriculum. Thanks to you over the years I am learning things I always wanted to learn without much difficulty.

[roshnimoses]

Your encouraging way of explanation, encourages me to learn electronics. Thanks Dave.

[Consul]

Technically every circuit is 100% efficient... as long as you want a heater to come preinstalled with every other device.

[markclark]

I learned all this in the '70s so this is a good refresher.

[Aan]

It's nice to go through it again, it is about 30 years since I was at the university and have been occupied at none electronics for 15 years, you don't forget it however it is far back in the brain and can be "hard to recall", so Thanks David 👍

[pj]

...and this is where I have to admit that I stopped (truly) advancing in electronics. I didn't want to do (read lazy here) the messy math around max power transfer that wasn't intuitive or useful in my mind. I did continue on but never really advanced until I went completely digital. This was before personal computers and spreadsheets. I have, however, circled back around (decades later) and am continuously learning. Thanks for teaching/re-teaching...

[dylancoppo]

Hey Dave, great to brush up on the fundamentals, and I will be giving the apprentices homework to watch your videos! I’m an auto electrician and thinking about the maximum power calculations in the automotive setting straight away made me think of a battery and a starter motor. Obviously it’s a bit different as internal resistance in a battery depends on many things including temperature. But it makes sense that having the battery and starter motor matched to get peak power across the load. When a battery ages and Sumgait on occurs internal resistance increases and the lid is no longer balanced for peak power. This can cause slow cranking, high current draw and low voltage. Through hands on experience I’ve seen the data and now you’ve shown me the theory and it made a happy match in my head! Thanks 🙏

[sir-gamesalot]

The timing of these "fundamentals" videos coincided with me picking up the Art of Electronics for the first time.

I really appreciate you making them!

[dwinsemius]

All these thermodynamic limits, i.e Pout < Pin, were discovered in the analysis of steam engines.

[Taran]

Great refresher course! Thank you very much.

[frenchcreekvalley]

Re the Ohm's Law Triangle: Maybe a small point, but we learned that you simply put your finger over the term you want and what's not covered is the answer.

[dranthonyv]

Bless you for excellent lessons to new players (and, in all humility, as long as we’re working toward our personal best, we are all new players at some point).
There’s a special place reserved in paradise for enthusiastic teachers like you. (enthousiastḗs "person inspired by a god" ).

[fnet]

Ohm's law is a physical law. In physics the voltage is denoted by U. After all, we denote the current with the letter I, and not A (amper) or C (current). :)