What does 'impedance matching' actually look like? (electricity waves)

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[JakeHarris]

As an RF Engineer, I live by this principle. It was really cool to see you approach it from the DC perspective and I am very impressed by your painstaking oscilloscope measurements!!! I have only ever seen plots like this in simulations, never with true measurements.

[minikindaniil]

You can also view terminating resistor as substitute for the rest of infinite wire. This way it's easier to understand why there is no reflected wave in this case

[einglis]

25 years ago I learned all this at university. But the depth of insight you've added to that basic knowledge is a revelation.

[MeriaDuck]

The fact that more or less consumer grade scopes can actually capture this is utterly brilliant. And then all the graph visualisations, especially the one with the 8 or so different resistance levels and see how impedance matching magically works... very very cool! And fairly important with everything with antenna's, especially high powered ones that will reflect significantly if not correctly matched, blowing up amplifiers in the process.

[bragapedro]

I don't often write comments, but WOW this was awesome. This, combined with the last video somehow got me to see an intense beauty in this "low-level", more advanced type of electrical properties. Thank you so much for this

[stonelaughter]

When I was a teen, I had a book about electronics by one G.M Scroggie. He described "transmission lines" in terms of a series of inductors in series with the two sides of the line, with capacitors across the two lines between each inductor. Basically a whole line of series/parallel tuned circuits which has an impedance related to the impedance of the capacitors and inductors. I didn't understand why, AT ALL. Now, thanks to THIS VIDEO, over 40 years later, I understand enough to SEE why you show it as tuned circuits. Not only that, but I know why the inductors are in series with the line, and the capacitors between the lines. I also see how the impedance works. I now understand why a CB Radio enthusiast needs a "Standing Wave Ratio" meter to ensure reflections are minimised at the aerial. This one series of videos has BLOWN MY MIND and I love it.

[jincyquones]

This doesn't just apply to long wire transmission lines. Changes in impedance on PCB traces or lines connected to them creates reflections and that's generally where noise comes from. Robert Feranec has a bunch of videos talking to a signal integrity expert, Eric Bogatin, and he basically explains everything you did in these videos but in the context of PCB design.

[kenmore]

At D.C., yes, it reaches an equilibrium quickly but the point of impedance matching is at high frequencies where peaks and dips of frequency response will occur if impedances aren't matched. I find it very interesting and enlightening seeing these high speed captures you are doing in understanding these phenomena. It makes it so much easier to see what is happening. It is distributed capacitance and inductance which creates the 150 Ohm (or whatever impedance, it depends on the cable configuration / geometry) and the distributed resistance which determines the Q (usually negligible), but the basis of why this happens is shown in the transient responses you are demonstrating. This is significant and will be appreciated by teachers in time. Please keep up the good work!

[NewtoRah]

If you use the electron motion visualization again in future, adding colour based on speed may make it a easier to see the changes in velocity, so blue is slow, red is fast, and rainbow or gradient between.

Also, this video should be required watching for every EE student, it explains and shows impendance 10x better than anything I got in school.

[Vidduley]

It was really interesting to see the dynamical demonstrations of pulses propagating and hitting the different loads! I didn't expect the real world waveforms to be so close to the ones you see in textbooks. Bravo to you!

[mcspikesky]

As someone working in testing motors for EVs, this video and the main channel one were GOLD! The Portuguese PhD who tries to educate me at work will love this, and hopefully i can understand more about EMC!

[SerpaJavier]

Let me tell you that this just made me make sense of the DMX line impedance loads used to avoid "reflections" in the line.... I knew about this ripples or waves of "voltage" but I couldn't figure it out why a load of an "apparent impedance" could work to "destroy" them.... This is just amazing.... Thank you.

[dougtaylor]

As a ham radio operator and long time mechanic and experimenter you have just explained something I could not see in my mind for 50 years. Now that I have a visual, it is unbelievably simple. I was like you about the coax cable. I never could see how a 15 foot piece of 50 ohm could be the same as 200 feet. That really bugged the piss out of me. Thanks for the video.

[DrenImeraj]

To have an idea of where the 150 ohm characteristic impedance of the cable is coming from, you can think of the wire having some inductivity and that there is some capacitance between the two twisted wires in the cable. If you would compute the series inductance and parallel capacitance, the resulting impedance would be 150 ohm. Of course, when modeling this, you would split the cable into an infinite number of sections and each section would have its inductance and capacitance resulting in the characteristic impedance of 150 ohms. You can thing of the wave propagation as the transfer of energy between those inductors and capacitors in the infinitesimal segments, each having a 150 ohm characteristic impedance. This also helps to think what happens when the wave leaves the last segment of the wire and hits a short or open.

[lmmlStudios]

As someone who has learnt this at uni, i can say these videos have been the best explanation i have ever seen

[boudewijnb]

The link to the main channel in the video description leads to an error page, because of an ')' at the end of the link.

[georgerocks]

Great physical explanation of impedance. Best I have seen...

[mlies]

I’ve been trying to understand this for 20 years and this video finally made it click. Thank you so much!

[metinozsavran]

Never seen this much honesty in anything related to electricity. My heartfelt thanks and prayers to universe that every EE in the world follows you. I hate just assuming things because somebody says so with oomph and authority. You deserve 8 million subscribers not just 8K. Just keep it basic and honest. This content is like watching Faraday himself at work. So innocent and humble.

[Ghostpalace]

4 years of engineering bachelor, and now i understand why the characteristic impedance is seen briefly by the Thanks!