Quite possibly the best film ever produced. Twenty-five action-packed minutes of high-energy (pun intended) transmission line science. "I give this video +3dB" - Gary Schwartz
Пікірлер: 98
@jaygade8 жыл бұрын
I've been working in radio and electronics for almost 30 years, and this is the best explanation of transmission lines that I have ever seen.
@bradleysmith6817 жыл бұрын
Absolutely!!
@Paul-gz5dp5 жыл бұрын
Even better when you can have hands on in a lab and see the stuff first hand.
@theoldbigmoose3 жыл бұрын
Me too! Lots of things so easily clarified.
@tedswimerr347 жыл бұрын
I have worked in the radio and radar industry for over 52 years and never fully understood the operation of transmission lines. This movie taught me more in 23 minutes about transmission lines than i learned in those 52 years. Kind of makes me wonder how many antenna jobs i screwed up!!!!!
@bradleysmith6816 жыл бұрын
Ted Swimerr I agree.. I understand the math but never really understood the real physics.. Imagine how much more we could fully understand electronics if all concepts were explained so well....
@Paul-gz5dp5 жыл бұрын
@@bradleysmith681 They are explained just as well and better if talking to the right people. I have known this for more than 30 years. Want to see one even worse try chasing down a ground loop sometime...
@wbeaty8 күн бұрын
When MIT tried this sort of thing in the 1990s, the students rose up in arms, and got rid of it. (This was Belcher's E&M course, with animated field-diagrams.) They wanted obscure math only. If it's taught without math, with visual-intuitive animations, then any mere technician can understand all the concepts! They put a stop to it. (The student-revolt was among physics students. It's like having a bunch of Medieval pre-meds who eliminate any professor who would teach, not in proper Latin, but in English which any outsider could understand.)
@dabay2005 жыл бұрын
Tektronix had a CRT scope in 1950s capable of a bandwidth of a few hundred MHz, very impressive
@billwesley7 жыл бұрын
Some people might think that this video is boring but actually it is exciting if you use imagination to understand the principals. Consider that these are also the principals of acoustics where a "reflection" is called an echo. A string on an musical instrument behaves exactly the same way constituting an acoustic transmission line with a small load, the string is plucked or bowed to create a pulse, this pulse travels to the end of the string and is inverted and reflected, then it is reflected again and re inverted off the opposite end. The pulse moves back and fourth making a tone that gradually decays. The instrument body functions as the load and the players motions as the temporarily connected battery. The pulse contains many harmonic frequencies and the nature of the load(the instrument body) verses the length and structure of the string determines the standing wave properties that filter the harmonics which provides the timbre (the tonal quality) of the instrument. Your breath is a battery, your vocal chords are a switch, your throat and nasal passage are two acoustic transmission lines and the air outside your lips and nose are the load. The transmission lines in this case are very complex with different adjustable impedance's distributed along their length( unlike an electronic transmission line with its consistent impedance) such that the end result is you can sing and speak. Most people think electronics are very abstract and remote form day to day existence but you are using these principals every to time you speak, you are appreciating these principals every time you listen to music.
@sunlongsun20713 жыл бұрын
wow
@MysticMonster72 жыл бұрын
amazingly written
@BenInSeattle3 жыл бұрын
I was watching this at 2× speed, kind of bored until about the six minute mark... and then I sat up and said, _whoa!_ I had to rewind because I'd never learned what characteristic impedance actually was. I knew the effect of an impedance mismatch was that the signal bounced, but I didn't get _why_ it did. In rapid succession there were three key things this video taught me about high frequency signals: 1. The insulator between conductors, even if it is air, is the "dielectric" of a capacitor. 2. Every wire, even an ideal one with zero resistance, has inductance. 3. To make it easier to conceptualize, it's okay to chop up the line into multiple segments of repeating inductors and capacitors that pass the signal one to the next. Also helpful was the reminder that the characteristic impedance Z = sqrt(L/C). Increasing the length of the cable increases L at the same rate it increases C, so it cancels out when calculating Z. Therefore, 4. Theoretically, a cable will have the same characteristic impedance no matter how long it is.
@phddgrd Жыл бұрын
After watching this kind of videos you're left with a profound sensation of awe and satisfaction about the vibe and delivery of this kind of content, now old style videos. Glad some of them are preserved in time in here...
@jimthvac1002 жыл бұрын
This is the first time I have understood impedance, reflection and velocity factor. Thank you for sharing this.
@MrBrightlight668 жыл бұрын
best depiction of basic transmission line theory in spite of age. Thumbs up.
@DCFusor7 жыл бұрын
Good stuff. For those who didn't know, the PC pci bus works like that reflected flattop signal at around 20: min. The driver only makes half the amplitude/current to get to logic level and the bus is sampled at reflection time so things see the full desired level. Fairly slick, but obviously length dependent in the extreme. If anyone worked with ECL back in the day, the only other good reference for this work was from Motorola ECL design handbook...and I still use the knowledge today.
@mrdouble Жыл бұрын
Oh my gosh, that's absolutely amazing, I'd like to find more Information on this. Any other links or book titles?
@gabotron9411 жыл бұрын
Now THIS... is a transmission line
@americanspirit8932 Жыл бұрын
We used tectonic oscilloscopes, when I was employed by Western Electric AT&T. It was to me, like a mechanic is to a wrench, or to a hammer is to a carpenter. In my opinion they made the best oscilloscopes available at that time.
@pseudolullus3 ай бұрын
Yup, we still use Tektronix in research labs :D
@CNLohr11 жыл бұрын
I actually screamed out loud at 13:38 because it offended my senses of what should and should not happen so deeply. I knew why and understood but never was it displayed so clearly to me.
@SkittleDash10 жыл бұрын
I feel old videos somehow hearth-warming :D
@jackriddle38912 жыл бұрын
100%. What people designed/made/did back then, doing their calculations on paper and slide rules! Really amazing. They had to know their stuff.
@GoSlash273 жыл бұрын
If you're still having trouble, AT&T Archive has an even better video; Similarities of Wave Behavior by Dr. John Shive. Definitely worth a look.
@c1t1z3nz3r011 ай бұрын
This video not only opened my eyes, it also open my skull, erased what i thought i knew about transmission lines and put back what i should know about transmission lines. Thanks for sharing it.
@abdullahsy70728 жыл бұрын
Thanks a lot for this video I wish there are more of these kinds of videos explaining fundamental things in telecommunication Engineering :)
@dvscrobe5 жыл бұрын
Wow! I stepped in a time machine here! That is some old footage. Best explanation I have heard on what is characteristic impedance. Very good info here!
@mgragirena14 жыл бұрын
Certainly this explanation of reflected waves from transmission lines is the best I have seen.
@TrystansWorkbench5 жыл бұрын
Wow - how good was that eh? Brilliant. So well explained. Thank you for uploading it and making it available for us to learn from.
@bradleysmith6817 жыл бұрын
Thanks for posting this!! Best explanation ever! Now I understand the basics that I've been looking for. These old training videos destroy anything produced today. If anyone wants to see some great explanation of antenna theory, look up the old videos titled "Antenna Fundamentals"
@ianirvingthorsonc Жыл бұрын
If i binge watched these videos 20 years ago in college, things would have been different 😅❤❤❤ magnificent..
@DonzLockz Жыл бұрын
These old videos explain principles and examples so much better than modern videos! 👍🍻
@aardrock2 жыл бұрын
Best explanation of transmission lines I ever saw. Simple, clear, concise, complete, tranquil, structured. Leads by example.
@lisizecha97594 ай бұрын
Old, but gold
@RoboGenesHimanshuVerma3 жыл бұрын
This is such a well made lecture !
@desawung38807 жыл бұрын
Great video, and great job explaining this concept from the ground up.
@MrSparker959 жыл бұрын
Thanks for the video! That's what i've been looking for.
@nizaribrahim8647 Жыл бұрын
this is the best video I have ever seen about impedance matching, thank you !
@Aemilindore5 жыл бұрын
Bless your mind for uploading thid! Lots of love!
@mrhoho11 ай бұрын
it is stupid that this video is more clear up to me than google search on 2023 and my elec engineering course.
@manueljenkin954 жыл бұрын
Thank you very much for sharing this gem.
@6alecapristrudel7 жыл бұрын
This is so amazing yet simple at the same time. I was wondering wtf that 50 Ohms thing was, the video makes it so intuitive>
@kevinkane76675 жыл бұрын
A fantastic lesson, a masterpiece of explanation.
@chung-fanyang40488 жыл бұрын
Better than tutor I met before. Thanks for the video.
@benthayermath5 ай бұрын
Fantastic!
@philradford271710 жыл бұрын
Cool video. I think we had an o scope like that in school in the 70's.
@vidasvv3 жыл бұрын
Great video ! TNX 4 the upload !
@atsdroid10 жыл бұрын
This should be required viewing for any radio amateur seeking a license beyond technician-class.
@Avalanchanime4 жыл бұрын
*Beautiful.*
@LUGUIM4Күн бұрын
Magnificent
@vargas00334 жыл бұрын
Thanks for sharing this video.
@jackyappu9 жыл бұрын
it have been explained well....now i had go idea about transmission line...thanks
@yoramstein7 жыл бұрын
Great video !
@victorogunjimi22069 жыл бұрын
Well presented and fun explanation - good job.
@LeKulverstukas5 жыл бұрын
And here I thought I got recommended a sick techno track. Bamboozled again!
@joet4348 Жыл бұрын
That’s really funny
@budimulyanto79975 жыл бұрын
great video. seeing is believing.
@techmakerandhacker786711 ай бұрын
nothing less than pure gold
@WistrelChianti4 жыл бұрын
That was an awesome video!
@TheAlfieobanz6 жыл бұрын
Wow...the vid was amazing.
@cevansinz Жыл бұрын
Ok. With a title like that I thought it was gonna be an electro-industrial track.
@StefanT41 Жыл бұрын
Amazing! i watched this with plesure
@mrhoho11 ай бұрын
thanks for sharing
@ZaphodHarkonnen2 жыл бұрын
Ohhhhhhhhhhhhhhhhhhhhh.... so that's what termination is. This video makes things so much clearer.
@mouseminer29783 жыл бұрын
Timeless
@carlosanvito3 жыл бұрын
Wish I had this video when I was in engineering school "a million" years ago.
@matthiasburger12772 жыл бұрын
Lernen unter optimalen, ist gleich beruhigenden Bedingungen. Sprecher, Musik, Geschwindigkei, perfekt.
@vidhyadhar64 Жыл бұрын
very good explanation...
@dancodella79115 жыл бұрын
They don't teach like this anymore
@TimPerfetto Жыл бұрын
Is this a transmission line? Is that a transmission line? Am I a transmission line? Are you a transmission line?
@RAndrewNeal Жыл бұрын
Now I finally understand transmission lines, characteristic impedance, and reflections. Now to apply this knowledge in the real world to RF and in helping better understand antenna theory. Though I still wonder why impedance matching and reflections aren't an issue at low frequency, with electrically short conductors (transmission lines). Particularly in the Audio world where power amp output impedance is ideally 0 Ohms, going into a load of a few to a few hundred Ohms. Oh, is it that the characteristic impedance of a transmission line is high enough to be negligible at low frequencies?
@iLoveEatingPie6 жыл бұрын
Is mayonnaise a transmission line?
10 жыл бұрын
that was my first experiment with an oscilloscope 6 years ago
@liryan9 жыл бұрын
Point 95!
@SquantoTerror8 жыл бұрын
+3 dB
@ElectricEvan7 жыл бұрын
Do we know who the narrator was?
@ch0vits10 жыл бұрын
where can i find this kind of old videos bout electronics and communication? please help!
@thewolfin10 жыл бұрын
On VHS in ancient school library archives.
@bobweiss86827 жыл бұрын
Looks a good deal older than VHS. 16mm film, maybe...
@user-ht1iz9xh5d4 жыл бұрын
There are some youtubbers like eevblog by Dave Jones and W2AEW about spectrum analyzers, mixers, rf signals, etc
@kennethwandall8375 Жыл бұрын
The current (electrons) are not moving lightning fast, the field (volt) is
@thecriticalpoint4 жыл бұрын
University programs are mostly overpriced trash. More often then not someone has to get over a language barrier before they can start to understand and integrate the basics. I love these videos.
@VideosLGful2 жыл бұрын
True, I learn a lot more watching these videos than a professor explaining about theories and mathematical calculations, without the most basic foundations, unfortunately universities today only form a bunch of illiterates, sad that.
@mejoe44411 ай бұрын
At 14:18 can someone tell me why those two waves on scope screen do not combine?
@bud8492 ай бұрын
The two waves do not combine because each occurred at a different time. The horizontal axis of oscilloscope is a range of time, not a single moment.
@Funkylogic6 жыл бұрын
More Tek Awesomenessness!!! Why would you buy any other CRO if you had the money!
@JoseSanchez-xd1oz Жыл бұрын
All wires are transmission lines.
@TechTins_Projects10 жыл бұрын
Jamie well done! fantastic find. Do you know if there are any more old videos like this anywhere?
@tonyfremont2 жыл бұрын
I'd have never guessed that Ronald Reagan knew so much about transmission line theory. Must have been between Hollywood gigs. ;)
@lwilton Жыл бұрын
Ronnie was a smart guy and knew quite a lot about quite a few things. He may well have known how a transmission line worked. However, I highly doubt he went up to Beaverton to voice this video. :-)
@stummstefan97353 жыл бұрын
wait...its all transmission line?!
@PaulMarostica2 жыл бұрын
For a short circuit, the return signal was said to be reflected. But aren't the short circuit's 2 emitted pulses each just transmitting through the short circuit to cross to and return in the opposite line, which explains the short circuit return signal's opposite polarity?
@lwilton Жыл бұрын
Well yes, but the major point is that the signal doesn't disappear at the end, it returns. And by convention we call that return a reflection when talking about transmission lines, regardless of the exact mismatch phenomenon causing the return. (If we were talking about radar, the reflection of the energy from the target is called a "return", just to be confusing.)
@PaulMarostica Жыл бұрын
@@lwilton Thanks. I think that, because there really is no reflection in a short circuit, to avoid further confusion, the convention should be changed. I don't find the radar reflection to be confusing, since it really is a reflection.
@pitdog75 Жыл бұрын
Guy sounds a bit like Spock.
@thewolfin11 жыл бұрын
watch?v=DovunOxlY1k This one's better, but doesn't have the same feel.