EEVblog

[@liambradymusic]

Hi Dave, that delay line blog triggered a memory from my colour television service time back in the '70's, a figure of 63.943uS comes to mind which is a half cycle short of 4.43361875MHz and was used to separate the R-Y ande B-Y colour difference signals for demodulation, it's all a bit vague now but that's what I remember, thanks for all your blogs Cheers Liam

[@movax20h]

Around 28:53 interesting things happen, you will see a bump on input transciver at 2*delay_time. These is back reflection captured back by input transciver. Cool. Leter you see bump at 3*delay_time at output transciver. Makes perfect sense.

[@Dibblah1900]

It is usable - Look at SAW touchscreens. Very cool in kiosk applications where you need them to be vandal proof. There is a significant amount of post-processing of the signal as well as wave guides laser cut in the glass. Cool video again!

[@Falcrist]

This is an amazing video for gaining an understanding of glass delay lines. It's clear, you're enthusiastic, and it seems to me to require some concentration from the viewer. These are all hallmarks of excellent educational content! Thumbs up, Dave.

[@Pieh0]

I was hoping to see some hard core silly-scope action from the delay lines, I was not disappointed.

[@gamccoy]

I did watch Mike's video and it was excellent. I loved this one, too. I also watch the "signal path" blog. I feel like a kid in a candy store with so many opportunities to get good information about EE. Keep 'em coming !!!

[@EEVblog]

Yes, it works like a circular access memory just like any other delay line type.

[@EEVblog]

That's the beauty of engineering. One product like that camcorder would be enough to spawn dozens or even hundreds of videos on various aspects of things!

[@scotttaylor215]

Fantastic description, thanks!

[@CMKenneth]

this video is absolutely fascinating, the whole component is pretty darn clever and obviously pretty robust on its operation quality. if it failed, or didn't perform up to spec the whole product would be useless.

[@StephenOwensTV]

I just wanted to say, your videos are a fantastic source of entertainment to me. On this channel and my others, you really do a great job ;) Steve

[@TunioMir]

Hey that last part, when Dave is squeezing the glass, is that how force gauge work?

[@ArumesYT]

No. When he touches the glass, the refraction properties change. Refraction index is always a result of two interacting materials, so glass/air has a different refraction index from glass/skin. His skin just absorbs a part of the signal, it is no longer reflected on the inside of the glass surface.

[@bulwinkle]

Surely at each reflection there's going to be a change of phase and a differential one to boot as each wave hits the reflective surface at an angle so that each wave hits the reflective surface progressively across each wavelength.

[@dougfgd]

First made by Telefunken a big bit of glass, ultimately cost reduced by treating as sliced bread i.e a single loaf of glass with piezo transducers sliced by a multiblade saw. Rough surface the result of the sawing process. Doug

[@laernulienlaernulienlaernu8953]

With things like this I always think of the clever guy who first thought it up and got it to work.

[@Jenny_Digital]

Intriguing... I fancy making a circuit that recycles some data though it to see how many times it'll go through before being mullered. I know it wasn't made for it but my obsession with vintage computing makes this into a good project for me. Keep uo the good vids Dave!

[@gavincurtis]

These are neat little devices. I still have an analog stereo TV (my first big purchase) from 1986 and there are 3 of these in the comb filter

[@EEVblog]

I had a try but could not get any internal reflection. Would likely have to coat the external edges with a mirror.

[@flubba86]

Do you think it would be possible to turn the squeezing-dampening effect into a pressure sensor of sorts? The attenuation of the amplitude looks very linear to your squeeze force.

[@Deckardsvr]

Yes, these devices are facinating !

[@WhitentonMike]

Dave, can you make a quick little video using a laser pointer pointed down the wave path? The inner child in me really wants to see the laser reflecting off all the angles as it goes down the wave path. Thank you Dave.

[@ottoodell_dell]

The LC groups are adding a little correction to the del.time +a bandpass filter of course ,extremelly important with the NTSC color systems ,and not quite so strict in the PAL (phase alternating lines)color encoding mode.

[@EEVblog]

On my youtube channel page, blog page, and in every mailbag video.

[@WhitentonMike]

Interesting, at 29:00 in the video we are seeing an echo in the source where the output reflected the signal backward through the delay line put a little blip on the input.

[@ElectronicsPubVideos]

Dave! Why do they use this delay lines in first place!?

[@eried]

Hi, this is a quick follow up vi--- 30+ minutes. Hahah! thanks for the lengthy videos!

[@WhitentonMike]

Bummer. Maybe a black marker would do the trick. If not perhaps some silver or chrome metallic paint. Worth a shot. Thank you for trying Dave.

[@JayLikesLasers]

I didn't see the first video. I'm not an EE. Didn't know what I was looking at, but heard that the thing transmitted analogue colour video signal and was like whoa technology...

[@elvishfiend]

Seems to me that the blip is a double reflection - from the input, reflect from output, reflect from input out output. The delay looks to be about 3 times the delay time, from the previous pulse

[@MisterNiles]

I'm here because I was looking at digital delay units to replace the lLine 6 DL4, which is notoriously breakable. Some "engineer" decided to use actuators and switches instead of just switches. The switches are small and mounted to the board. They break. Now I'm fantasizing that this would work with audio. Thinking about how different types of glass would sound. How large one of these would have to be to make audio delays? My most common open loop time is between 4 and 8 seconds. Yeah. Pretty huge, and more breakable than my guitar pedal I imagine.

[@EEVblog]

I doubt it's linear over any usable range. And there would likely be all sorts of horrible edge effects on the channel(s) it's compressing or whatever. And the range would be very limited. I think you'd find that looks are deceiving here.

[@Fake0Name]

Jeeez, turn the hold-off on your scope up! That triggering jitter is driving me nuts.

[@EEVblog]

Yes, but it's 192us in this case.

[@Pieh0]

There's lots to choose from :P

[@bryanmullins2063]

You would expect the waves to interfere with themselves at each crosspoint, I wonder why it doesn't or perhaps thats where that little shadow comes from

[@Quadraphonicsoul]

I had the transcript up here is one of the funny lines 7:30 the train houston here because the tightest tonight a properly

[@EEVblog]

No, this has nothing to do with circular access memory. I didn't have any time in the last video to do any measurements on the thing.

[@jspencerg]

Dave: excellent presentation. Unfortunately, the delay line link at Morgan technical is gone. Is there a way for me to get this paper?

[@Tadesan]

you don't expect any more out than you put in? nice work.

[@yasirnoori4848]

That's amazing Dave, thanks a lot. I do similar stuff with photonic wavelengths. We call them slow light delay lines.

[@EEVblog]

That's always the intention...

[@mattcysiewski111]

hmm this delay could also be used as a very crude pressure sensor

[@Pieh0]

Not everything in electronics is fun and exciting.

[@frollard]

it seems to affect the amplitude but not the delay, fancy.

[@WhitentonMike]

Check the video at the 29:00 mark give or take 10 seconds. Sure looks like an echo to me.

[@EEVblog]

That's the idea :-P

[@FrankenPC]

Yeah, interesting. So is the drastic change to attenuation.

[@aptsys]

Mike already did it.

[@WhitentonMike]

Sorry, didn't catch that you were replying to me. My bad.

[@killernoob756]

Whats the adders to send you stuff?

[@jschroedl983]

but why do you need this?

[@marshaul]

Watch part 1.

[@noname_atall]

analog colour video decoding, for instance. at least PAL signals require that.

[@SummerFunMan]

Wow, I wonder if the bachelor's-degree version of electronics engineering technology at ITT Technical institute would've taught about these, because I surely didn't get it as part of the associate's degree. I wonder if they teach this during AAS at UVSC/UVU.

[@rich1051414]

Maxx Fordham Well, it is your responsibility to continue learning relevant information for your field after you graduate. No one knows everything they need to know for their career on graduation day, but are given the tools needed to figure it out as you go :) ITT Tech was much better at teaching relevant material than a proper university was, so i seriously doubt they taught these either, unless they just happen to come up for a project.

[@SummerFunMan]

But, Richard Smith, other than being given the knowledge "tools" you needed to know about something like this at a job that had them, you wouldn't know to look for something like this and learn more about it if you didn't even know it existed in the first place. Maybe a college-level school somewhere taught about these in a bachelor level.

[@JohnDoe-qx3zs]

They were in textbooks for ordinary TV repairmen back when still in use.

[@SummerFunMan]

Ahh, okay, cool. But now I just remembered that I think there are specific repair manuals that authorized repair shops can get. Right? Happy Rio Olympics! Don't forget to watch some during these next 2 weeks.

[@realcygnus]

way cool channel......+ the dude just cracks me up

[@msjaxp]

Nice :)

[@NicklasUlvnas]

just check out /watch?v=VVMHXO0-VGY&t=12m21s and you have it both in text and audio...

[@aptsys]

Posh equipment, but unable to use it... Lol.

[@fos5932]

Dave, your understanding of resonant modes is a bit lacking! I know you're an engineer but you're slightly misleading your viewers about the theory behind the response of the system.

[@katatonos1]

I've heard him say repeatedly that anyone with more accurate information should pipe up.

[@SirDrinksAlot69]

Could another variable affecting the delay not be your greasy Australian fingers leaving stuff on the surface of the glass? ;)

[@billysgeo]

I like how you say "just a quick video" and it turns out to be half an hour! LOL!!!

[@bpa5721]

wow, so beautiful because it's so simple

[@mkubiak67]

I love watching your videos there vary good... I remember taking one of them apart in our old JC Penny VCR from 86~87 that was when I was 15 years old. I didn’t know what they where till i stumbled on to your Video now thanks! P.S. Watching your videos have stared me getting all my electronics stuff out of the dust and started looking for new equipment.

[@FrankenPC]

I wonder if there is a reflection from the pickup transducer that travels all the way back then reflect back again to the pickup. A blip which has an offset of 128micro seconds.

[@jaimeesg]

Hi, what happens at 14,7 khz (1/68usec) and at 7,35khz (maybe a resonance...)?

[@TheUbuntuGuy]

Trying to show up mike, are we?

[@HeartOfGermany]

Wow, how many Videos about that camcorder!!! o.O

[@天津勘三郎]

I was making also in our company.

[@chemtype]

Although your testing methodology is undoubtedly accurate, wouldn't is have been much easier to use two channels on your scope reading the same signal? With one probe reading the delay-line and the other being a direct path? and using the scope to show a comparison of the two channels? It seems like it would be a simpler and more robust solution.

[@Shroommduke]

I wonder if light frequencies will have an effect the signal more interesting stuff... Storing 32 bits of data in a piece of glass November 9, 2012 By Brian Benchoff 32 Comments

[@FrozenHaxor]

Excellent! I love how Dave is mastering the scope, making everything so easy in just a blink of an eye!

[@dinkc64]

I absolutely love this kinda stuff, thanks from Michigan, u.s.!

[@HeartOfGermany]

I'd love that as a job! That'd keep me busy for nights!

[@killernoob756]

ok tnaks

[@martinexex]

Hi, could anyone explain me why is still the green signal at 19:05 and what is "capacitive coupling"?

[@neut1121]

he's using a breadboard to do the testing.. breadboard has parallel metal contacts which are close to each other acting as a capacitor.. this capacitor will high pass signals across terminals.. Google breadboard stray capacitance for more info :)

[@tixiv23]

Dave, you need to stop repeating your self all the time. I often get bored then, and only skip throught the rest of the video. You need to condense the information more. Look at mike's Videos. He knows how to do that.