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#transmissionlines#impedancematching#signalpropagation

Watch electricity hit a fork in the road at half a billion frames per second

AlphaPhoenix

725K subscribers • 2 videos on Hallway

YouTube
  • Recommended by 5 people: 5 on Hacker News.

Intermediate. Assumes working knowledge.

2.9M views2 years ago5 recommendations

HardwareSystems programmingElectronicsCPUs and computer architecture

AlphaPhoenix uses a high-speed measurement setup to visualize how voltage waves travel down transmission lines and split at a fork.

In this video, I measure a wave of electricity traveling down a wire, and answer the question - how does electricity know where to go? How does "electricity" "decide" where electrons should be moving in wires, and how long does that process take? Spoiler alert - very fast! I've been very excited about this project for a while - it was a lot of work to figure out a reliable way to make these measurements, but I've learned SO much by actually watching waves travel down wires, and I hope you do too! There will be a Q&A about this video posted in a few weeks on the second channel, and if you head over there right now, you'll see two direct follow ups to this video with experimental details, and a section about "impedance matching" that was cut from this script. youtube.com/@AlphaPhoenix2 Special thanks to my top Patreon supporters! birdiesnbritts John Sosa Trustham Vladimir Shklovsky Aloysius Sparglepartz Ryan M Jason Whatley Lohann Paterno Coutinho Ferreira Kasper Nielsen Jeffrey Mckishen patreon.com/AlphaPhoenix Media Credits: Slomoguys clip used with permission. Thanks Gav! youtube.com/watch?v=nsJGJHkJolI I Dunno by grapes is licensed under a Creative Commons Attribution license (creativecommons.org/licenses/...) ccmixter.org/files/grapes/16626 Arcadia - Wonders by Kevin MacLeod is licensed under a Creative Commons Attribution license (creativecommons.org/licenses/by/4.0/) Source: incompetech.com/music/royalty-free/index.html?isrc=USUAN1100… Artist: incompetech.com/ a hypothetical question Measurement difficulties Individual oscilloscope traces Electricity moves through Y circuit The single wire experiment – how electrons move Electrons hitting a dead end Revisiting the Y circuit The water channel model

Why it's here

5 people recommend this

What people say. Highly recommended as an exceptional, visual explanation of electricity, signal propagation, and impedance matching in circuits.

simcop2387on Hacker News • Recommends

On “Wireless power transfer system achieves 270-kilowatt charge”

This spurred on some other videos from another youtuber that goes by AlphaPhoenix, he went way into all the details on it including measuring the complete flow of the wave of the electrical power and how it all works. link link to this video link (on his second channel, has a lot of "behind the scenes" of how it was done) It goes into a lot of depth of how the wave propagates, including measuring it at effectively "a billion fps" (he goes over how he does this) along the wire and how impedance matching works, etc. It's about 2.5 hours of video IIRC but it's probably the most detailed and easy to understand demonstration and explanation of all of it that I've ever seen.
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spaceywillyon Hacker News • Recommends

On “Why does current flow the opposite way from the electrons?”

As a matter of fact, yes! This YouTube video is probably one of the most amazing things I have ever seen, he measured the change in voltage traveling along a Y circuit, where one end is open and one is closed. You can see the voltage “ripple” through both branches of the circuit, reflect of the ends of the branches, and eventually settle into steady state. There are limits to this way of thinking (for example, water can’t travel in the space between “tubes”, but electricity can), but it is a very good way to approximate it. link to this video
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brunohaidon Hacker News • Recommends

On “Oliver Heaviside and the theory of transmission lines (2021)”

Excellent post! Controlled impedance took me a long time to wrap my head around when starting PCB design, the moment when it finally clicked was watching this excellent AlphaPhoenix video link to this video asking and practically demonstrating the simple question: When you flip on a switch, to turn on anything, send data, morse something etc, how does the circuit know how much current the load at the other end needs? Spoiler: Given that information can't travel faster than light, the simple answer is: it doesn't. So it just guesses and adjusts, which you don't want as it gives you exactly the ringing etc Heaviside identified. The video is a nice complement, as it perfectly visualizes the issues at play…
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andrewflnron Hacker News • Recommends

On “Science Communications on YouTube”

I want to hijack this comment to plug AlphaPhoenix ( link ), who is responsible for by far the best explanations of electricity that I've encountered in any format. For instance, this one that clarifies what happens when you try to send electricity on an open circuit, and (IIRC this is the right one) what impedance mismatch is actually about: link to this video
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kzrdudeon Hacker News • Recommends

On “But good sir, what is electricity?”

AlphaPhoenix's measurements, experiments and visualisations really help! They show some things that are normally not even taught and even electrical engineers will appreciate to see this. This video he made about it is very good, and worth watching if you wonder about how electricity propagates from one end of a conductor to the other. link to this video
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spaceywillyon Hacker News • Recommends

On “Physicists Make Electrons Flow Like Water”

Well, the water analogy actually holds up quite well if you consider the charge field moving, not the electrons themselves. This guy has a lot of great videos using water channels to explain electricity. It is fascinating how under a high speed scope, you can see the electrical Charge “flow” like water down each branch of a circuit. link to this video
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schiffernon Hacker News • Mentions

On “Basic Mechanisms In Fire Control Computers (1953) [video]”

The neat part is that it's almost instantaneous, but not quite. How electricity flows through analog circuits and chooses the right path is another fascinating subject. Seeing how it actually works "in action" seems to glimpse some insights into ultra-fast computing paradigms: not just computing with analog circuits, but also structuring computation like circuits. link to this video
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kragenon Hacker News • Mentions

On “How to succeed in MrBeast production (Leaked PDF)”

well, the truth turned out to be quite complicated; see also link and link to this video . the result is more complicated than just a single time delay, and the details of the experimental setup (like the wire diameter! and load impedance relative to transmission-line pulse impedance) matter a lot. in alphaphoenix's first experiment, putting 5 volts into a kilometer of wire, he got 0.2 volts across his resistor immediately, then after about 1.6μs, a jump up to about 2 volts, and then a gradual rise to 1.7 volts, some overshoot peaking after another 1.6μs, and then settling back down to the 1.7-volt level (derek's results in the linked video, which incidentally links to one of the two i linked above,…
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hnuser123456on Hacker News • Mentions

On “How far neuroscience is from understanding brains (2023)”

Turns out "water in a pipe" is actually surprisingly accurate, just that the "waves" are sloshing around at half the speed of light. link to this video
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