Analog VS Digital Scopes for Glitch Captue

Another Twitter question, a demo of the vast superiority of digital oscilloscopes compared to analog scopes when detecting infrequent glitches. And the importance of Persistence mode in debugging.
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#ElectronicsCreators #Tektronix #oscilloscope

[@DrFrank-xj9bc]

Once upon a time, there were pure analogue scopes, which had a special cathode-ray tube with analogue persistence, i.e. storage tubes.

[@jenniferwhitewolf3784]

I still use one... Tektronix 7734, 400MHz, 4 bay modular analog scope. I have an array of vertical amplifiers to choose from, and it is equipped with 2) 7B92A time base plug-ins. When it was new, it cost more than my house.

[@andye2005]

Horribly expensive! Very good for capturing fast pulses, but the storage decayed away quite quickly. Going back nearly 40 years now, so if I remember correctly there was a fine mesh screen in front of the phosphor which was "Lit" by a separate electron gun a " flood gun " this charged up the mesh or maybe discharged it, when the normal electron beam hit the mesh it changed the charge on it, and that's what the phosphor showed. The mesh slowly lost it's charge, and then the image washed out. (I remember the display slowly getting brighter all the time) So you frequently needed to erase the image and start over. Not something that you would leave on for hours at a time, maybe a minute or two if you were lucky. I've probably got some of that backwards, but you will get the idea. Andy

[@MrSlehofer]

@@andye2005 properly adjusted storage tube can store a waveform reliably for hours without the "washing out" effect you mentioned (it all depends on the flood gun emission and its colimation, which has a sweetspot where it maintains the waveform nicely, too much the image got brighter and eventually washed out, too little and the image would slowly dissapear). Also as with all analog instruments, for maximal accuracy you need to let them warm up for some time (hour or 2), so in your case if you just turned the instument on to capture some waveforms without letting it warm up first then the flood gun emission was likely out of cal and cause all those issues you mentioned.

[@EEVblog2]

They were neat, but still not as good as a digital scope for this purpose.

[@andye2005]

@@MrSlehofer Interesting, The scope in question was some sort of Tek, and as far as I know it was never able to store a image for more than a few mins. As it was the only one of two such scopes in the company, it wold not surprise me if it had some sort of fault on it. I found the second storage scope (an HP model) on the bottom shelf of the "dead" test equipment racks. The repair cost for it was so high that it was still there when I left the company. Andy

[@joehubler4965]

The technique I used on an analog scope back in my day, required a time exposure with a polaroid. yep, I'm that old.

[@marcosfeddersen5114]

Analog persistence mode

[@shanesrandoms]

Or the Bil Herd way, stare at the scope, then look at a blank wall and you will see the faint glitches 😉🤣

[@KeritechElectronics]

I'll have to try that; got a Soviet S1-64 analog scope that appears to have long-ish afterglow.

[@andye2005]

Used to do just that when looking at Radar tubes. We have a 3ft long tube that you shoved over the display and there was a hole at the other end for the camera. So no problems with focus and so on. Open the shutter, count to 4 and then release. Worked very nicely. We also has "adaptors" to use the camera on scopes. Andy

[@ianm144]

Yip I used black and white polaroid to catch glitches in the day (early 90's). Opened shutter on camera, ran test software, when error detected close shutter, develop film, wave it around, wave it a bit more and there it was, in black and white, a 10ns runt pulse on the write line of a FIFO causing the empty and full flags to get out of step. One cause was ground bounce, as pulse was value of data related (no of 1's in the word) and other only seen when using the outer output pins of GALs. Those were the days.

[@sefarkas0]

First to trigger

[@bobcarter6143]

Takes me back 40 years to when I had to create an almost identical test signal, runt and single bit jitter, to test an early hard disk head amp signal detector board….

[@w2aew]

Dave - you know that you can "swipe" those un-displayed Math waveforms off of the screen.... Just swipe the "badge" off the bottom of the display...

[@EEVblog2]

Well now I know.

[@w2aew]

@@EEVblog2 Same thing for the measurements - you can swipe them off the screen to the right. Also, if you have no measurements and want more area for the waveforms - touch/click the small vertical group of three dots on the right edge of the waveform graticule - this will collapse the measurement badge area, expanding the waveform view. Tap the dots again to re-open the measurement badge area.

[@harbselectronicslab3551]

I'd just like to say TEK 2467BHD Bright Eye........that is all

[@OneBiOzZ]

Something i would like to see (and have been bitten by) is if you can actually run these scopes for a week while they capture in either infinite persistence or in masked pass/fail mode without crashing/locking up/overheating

[@EEVblog2]

I've done it many times. Never had a scope lock up on me.

[@jenniferwhitewolf3784]

This is why I have a Tek 7834, Storage scope. It has 'persistence' too, long before Tek, actually Hiro Moriyasu at Tektronix, invented the digital scope. I happen to own Hiro's personal 7704A/P7001 digital scope, and a Tek 7D20 Programable Digitizer for 7000 mainframes. Surrounded by the high end 7000 series mainframes, the 2247A with digital co-processor, is my only pure digital scope, a Siglent 200MHz SDS2202x-E. It mostly gets used in FFT mode being fed from the residual out of an analog Tektronix AA501A distortion analyzer.

[@NivagSwerdna]

now... reverse engineer the glitch generator... !

[@cnxunuo]

Great use case for a Tek 2467B MCP CRT!

[@reinerfranke5436]

The microchannel plate in Tek 2467 and 11300 can show rare events.

[@jspencerg]

Yep, the 2467 had its "brighteye" micro channel intensifier running at 350 or 400(2467B) Mhz. I'm lucky to have this classic, still great analog scope.

[@w2aew]

And don't forget the 7104...

[@borislipschitz2740]

I clearly recall older Tektronix scopes (digital ones) having "peak detect" sampling mode. This helped A LOT with spotting glitches.

[@humgar]

HP 54616B also have peak detect sampling mode.

[@kevingilbaugh6278]

Suggest you turn on digital mode on the Fluke.

[@reedreamer9518]

Dave - you left out the Siglent SPO (Super Phosphor Oscilloscope) effect! Being a SPO fan-boy I feel a little left out - whaaaaah ; (

[@RogerWilco486]

Dave, does this thing not have some kind of "runt" trigger mode to help capture these kinds of anomalous events?

[@LutzSchafer]

Yeah but a decent analog tek scope also has a dual time base and holdoff. If setup right you can dim the first time base and then see your runt pulse.

[@proluxelectronics7419]

I don't get it, a pure analogue scope would not be taking time to do things like on-screen graphics, just the phosphor decay and high speed eyeball refresh rate, (what happened to emoji smily face)

[@Evergreen64]

So now is there a better use case for an analog scope. Something that it will catch or see where a digital scope won't see it?

[@kei_otake]

I’m sorry, but something about these new scopes and tapping screens like a low-rent knockoff tablet will always give me the heebie jeebies. Give me peak detect on an analog over this weird, unfriendly digital interface any day.

[@TheDefpom]

Isn’t that fluke scope digitising the capture first? I’ve had better results from a true analogue scope (dick smith 60MHz job) over my digitising 300MHz tektronix 2432A

[@EEVblog2]

Nope, pure analog.

[@Retep4565]

Analog scopes with digital readout like the one in this video have some dead time during which instead of the waveform the text on the screen is drawn. Turning off the readout avoids this dead time. Would it make glitches clearly visible? Probably not.

[@belesiu]

Great video! QQ - does the Tek-2 have a glitch trigger? Many of the ‘scopes at work have a trigger mode setting (usually single sweep or “normal”, not auto) to fire when a narrow pulse occurs. I’ve used this feature for years on Tek and H-P/Agilent/Keysight ‘scopes and I suspect the Tek-2 might have this feature as well.

[@BlackEpyon]

My first analog scope (Beckman Industrial 9020) got more "glitches" from dirty pots than anything. Still have it. One day, when I get around to it, I'd like to take it fully apart and give the thing a good cleaning so I can pass it on to somebody else, because it served me well for years, and is a very nice entry-level scope.

[@byronwatkins2565]

Turn up the vertical gain on the analog scope so the brightest horizontal lines are off-screen. This avoids burning the phosphors and makes your eyes slightly more sensitive to the rare events. If you suspect a glitch, this often makes it visible. You can also tweak the focus (and astigmatism if it is equipped). Older analog scopes had less brightness limitation to protect the phosphors and were more useful for this... but required more care to avoid damage.

[@-szega]

A 7603 from 50 years ago will vastly outdo this newfangled Tektronix because it does around 1.5 million waveforms per second. Okay, they're all averaged together so you don't actually see them... but still. Millions of waveforms per second! 60s technology!

[@billjohnson3344]

Good video Dave. The scenario you demo here is nice, but not always is the 'good' signal perfectly periodic like that. With a dynamic signal, runts like this are often hidden anyway and not so easy to spot. The other thing that runt generator is good for is testing the scope's smart triggering. With this scope, can you set up a smart trigger to consistently catch the glitch?

[@trevthea5781]

This is a good video. Thanks Dave. 😊 I was initially impressed by the form factor but am not impressed by its functionality. It's a bit meh.

[@LogiForce86]

Thought about getting a 50 euro Tek 2205 secondhand but it's big and it's analog (which is clearly a downside). So I might want to save up for a modern digital jobbie that doesn't take up the desk realestate.

[@gerardoromano3436]

Hi at 2:50 It´s electron not Photons LOL, anyway, great video Dave! Cheers

[@mengisi]

Try to use Tektronix 2467B, with "B" letter.

[@Seiskid]

This is a good video - had no idea my scope had this feature - just checked - it does indeed.

[@Neuroszima]

what does exactly mean "milion waveform updates per second" Also Signal Path already did a video on this issue, and he got reallly frequent glitch updates, to the point that he isolated this pretty much exclusively

[@helmuthschultes9243]

Poor variable persistence design there, should use fadeout time constant not sudden blanking to do variable persistence.

[@rkan2]

Ah yes, next these scopes can go into 500Hz displays too :D (They are just coming to market for gaming)

[@NivagSwerdna]

I really should upgrade my first and only scope which I bought after watching a review by some aussie bloke back in kzbin.info/www/bejne/oZXNoZWNgc5qi6s that video doesn't even have a number! Would be interesting in any views of current entry level 4CH scopes if any new and affordable ones appear.

[@antoniomonteiro1203]

I'm curious about Tektronix's response to this video...

[@StreuB1]

Furst? Edit: That was REALLY interesting!!!

[@KeritechElectronics]

Interesting. I saw that glitch on your previous video and gotta say it's a pesky little bugger.

[@EEVblog2]

It's a very handy test signal!

[@KeritechElectronics]

@@EEVblog2 true, no matter if it's intended functionality or not :)

[@Meiestrix]

When you think that there might be a glitch you could also try the Mask Test / Pass Fail Test.

[@MichaelKingsfordGray]

I bailed after the 42nd "ahh..." at 5 seconds in.

[@delatronics3257]

Interesting to actually see what jitter looks like.

[@antoniomonteiro1203]

At 2:55 you meany electrons, not photons...

[@gamerpaddy]

have you ever looked at a dscope u3p100 usb oscilloscope? i had the very first dscope which required windows to disable driver signature enforcement and only had like 200MS/s but did a great job but replaced it with a siglent entry level scope, still the dscope had better fft, better ui but less math functions, specs, channels and voltage range at the time

[@mikejones-vd3fg]

Cool,Im looking into something like this, but almost $500 is alittle much and the reason i was looking into something like this was for it to be a lot cheaper, and did find a similar thing for around $100. Its software was terrible and so are the specs but the opensource software for it was reportedly good. Some guy said it chagned the oscilliscope, which had me thinking how much of it is dependant on hardware and how much software? What the bare minium hardware you'd need to get this data for a computer to interpret? Could an Arduino solution be good enough? I was looking into something like this aswell kzbin.info/www/bejne/gqHFfIOfrJtolbM

[@indian.techsupport]

For running it long pass/fail mode is better

[@reddcube]

How is this not a main channel video?

[@JAKOB1977]

Any reason you use that demo board for these glitch test as I guess not many have those, whereas cheap crude signal generators are all around. If I wanted to replicate it, with fx a signal generator ( (a cheap 65 USD FY6900-60Mhz)to see how my own scope stacks up in the same situation, how would I achieve it to make it as close to that situation as this tek-demo board..? just to get myself an overview of how my own scope stacks up in a likewise situation. I often do that, as a way to learn as a newcomer.. simply try to replicate tests from more skilled people, and then learn while I do it... but these special demoboards you have.. its all relative' what actually takes place..

[@dsfryda]

What about the Rigol 1054Z, is that scope able to pickup that defect, would be curious how that famous entry level scope competes with these newer ones.

[@mepacrina9291]

2:53 ... the electrons ... But this is not the subject. The thing is that on some analog Tektronix you probably will see much better the glitches ;) Not to mention the analog (mesh) memory type . The digital is better, you are right but the lower cost have still problems (aliasing, arming delays, software bottleneck after some hour of use ... and so... only the high price ones are actually better in every aspect).

[@worroSfOretsevraH]

More scope videos!

[@So-Flo]

It's surprising how much these things cost considering how infrequently they bring out new models

[@ernestb.2377]

Nice video on how to use the persistence function 👍 Maybe you could also see the glitch with the averaging function?

[@derkeksinator17]

a couple of seconds of persistence in dot mode is better than interpolation as well! At lewast for the people that actually want to put 1GHz into a frontend.

[@JAKOB1977]

when you in perstance mode.. wouldnt color intensity be able to highlight that rare glitch even better and give you an indication of the rarity after the fact, if you let it run for a long time-

[@MLX1401]

I'd love to see this Tek test board featured at Mr. Carlsons lab 😄

[@milk-it]

Love it. You should write a course on how to use an oscilloscope ;-).

[@jeanyvespochez]

and is the old combiscope in digital mode able to detect these glitches ????

[@bradbrown620]

What about a "digitizing " scope?

[@1010tesla]

what is the failure that causes a runt pulse? I can't say I have ever seen one in the wild, only on demo boards.

[@w2aew]

Runt pulses often happen with "bus contention", where two devices try to drive a bus line simultaneously (to opposite states).

[@sfred]

This was very helpful.

[@michel5148]

dtb? delayed time base?

[@benedienst]

Unfair comparison between analog and digital would be with a Tek 7104 or 2467 with MCP CRT.

[@w2aew]

I have a 2467 - I might have to do this... ;-)

[@benedienst]

@@w2aew there was so much wizardry involved with the 246x series. Absolute peak of analog scope tech.

[@raymonddompfrank1789]

MCP CRT-equippped 'scopes like a Tek 7104 or 2467(B) have no problem showing those rare events happening at 1/10000 - 1/1000 duty cycle. Problem is that the brightness (of the regular signal) would have to be set rather high, adversely affecting lifetime of the MCP CRT. On a Tek TDS3000-series 'scope (3kwfms/s) runt triggering and using longer persistence helps a lot - but you have to wait till it catches the event!

[@oskimac]

Almost there. You won

[@catalinalb1722]

Dave... Are photons real or is just waves? 🤔

[@EEVblog2]

Depends if you are watching or not.

[@catalinalb1722]

@@EEVblog2 😂

[@outronomem297]

Are waves real or just photons?...

[@bluegizmo1983]

No, your wrong! Analog Scopes are the only real scope, if the signal doesn't show up on an analog Scope it's not really there!! AHHHH!!! 🤣😂🤣 That's what all the analog purists are screaming right now

[@KA6WKE]

Typo in title - Capture :) Great video though!