Author Topic: True analog scopes  (Read 50463 times)

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Offline adam4521

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Re: True analog scopes
« Reply #250 on: December 20, 2022, 09:17:51 pm »
I think, to summarise this energetic thread, that ‘true analog scope’ aka CRO has for some time transitioned to heritage technology. If you are a hobbyist, it depends a bit on what form or direction your hobby takes, but for someone learning modern electronics, a DSO is surely the right proposition if you can get one. There are still compromises at the very bottom end, but if you reach for the Rigol/Siglent/Instek/Micsig arena, the machine will be very functional, modern, with warranty protection.

I thought I would make a comment though about the historic significance of the CROs. Everyone who has used one will have cranked the timebase to maximum time, and watched the bright dot process smoothly across at constant speed, left to right, before flicking back and tracking across again.

But now at fast (but not exceptional) timebase of 20ns/div — get your calculator out to check me — the same beam is tracking horizontally at 500000 m/s, a horizontal line speed of more than 300 miles/second! And the thing that remains astounding for me is that it can repeatedly trigger and track the same groove on the screen, with calibrated speed and mm accuracy. Outside of a physics lab, I’m not sure if anything on earth moves that fast!

This humble vacuum tube ‘etch-a-sketch’ enabled us to see and study things in the natural world that were impossible otherwise. It must surely be one of the most significant inventions of the 20th century, shaping our contemporary world, including the world of computers and, of course, making DSOs possible.

So even if CRO is not for electronics any more, the concept, what was achieved with these machines, still worthy of respect. Might help explain why some of us still hang on to them.

 
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Offline joeqsmith

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Re: True analog scopes
« Reply #251 on: December 20, 2022, 10:21:04 pm »
5" screen, 10 div, 20ns per div or 200ns to travel 5".  That's 25,000,000 in/sec or 395 miles/sec. 

I suspect my first analog scope was maybe 1MHz at best.  As we got faster scopes,  I found myself turning off the lights to see the trace.  We had phosphor storage and our poloroid cameras which I guess helped.  How many of us were triggering the scope with our custom delayed trigger to sequence though the sweep, collecting all those photos, allowing minutes to expose, then digitizing that..... 

Then again, the first DSO we had was a Tek 7000 maybe mainframe.  From my memory, the downtime was more than the uptime. 

Considering used vs new,  a 500 MHz is $5890.   22 years ago, I bought my LeCroy  7200.   I think I paid $600 back then.  I had to hack in a different hard drive.   To be fair, I have had to repair it a few times over the years.   It still runs today and I fire it up from time to time when making videos.   The analog BW is 4GHz.  For non-repetitive waveforms, it has a 500MHz BW and can sample one channel interlaced at 2Gsps.  It has a fair amount of built in math functions along with TDR measurements. 

Then again I'm talking about a product produced in the late 1980s, and I'm sure the scope you mention would out perform it in many ways. 

Offline bdunham7

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Re: True analog scopes
« Reply #252 on: December 20, 2022, 10:55:52 pm »
But now at fast (but not exceptional) timebase of 20ns/div — get your calculator out to check me — the same beam is tracking horizontally at 500000 m/s, a horizontal line speed of more than 300 miles/second! And the thing that remains astounding for me is that it can repeatedly trigger and track the same groove on the screen, with calibrated speed and mm accuracy. Outside of a physics lab, I’m not sure if anything on earth moves that fast!

Well, it really isn't 'moving', so there's no limit, not even the speed of light.  A Tek 2465B can move the dot (mostly vertically) over 8cm in 700ps.   That's about 71,500 miles per second or ~0.4c.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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Online tautech

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Re: True analog scopes
« Reply #253 on: December 20, 2022, 11:22:03 pm »
But now at fast (but not exceptional) timebase of 20ns/div — get your calculator out to check me — the same beam is tracking horizontally at 500000 m/s, a horizontal line speed of more than 300 miles/second! And the thing that remains astounding for me is that it can repeatedly trigger and track the same groove on the screen, with calibrated speed and mm accuracy. Outside of a physics lab, I’m not sure if anything on earth moves that fast!

Well, it really isn't 'moving', so there's no limit, not even the speed of light.  A Tek 2465B can move the dot (mostly vertically) over 8cm in 700ps.   That's about 71,500 miles per second or ~0.4c.
Which without some form of persistence is arguably of no use to anyone.
It only needs be as fast as we can see which for a repetitive waveform gets multiple writes to the display faster than we can observe.
In a DSO we still have Normal and Single to see and capture these fast events.
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Offline David Hess

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Re: True analog scopes
« Reply #254 on: December 21, 2022, 06:32:19 am »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

https://web.archive.org/web/20110926020847/http://www.oregonlive.com/silicon-forest/index.ssf/2011/09/a_tektronix_oscilloscope_that.html
 
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Offline Fungus

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Re: True analog scopes
« Reply #255 on: December 21, 2022, 06:44:11 am »
But now at fast (but not exceptional) timebase of 20ns/div — get your calculator out to check me — the same beam is tracking horizontally at 500000 m/s, a horizontal line speed of more than 300 miles/second! And the thing that remains astounding for me is that it can repeatedly trigger and track the same groove on the screen, with calibrated speed and mm accuracy. Outside of a physics lab, I’m not sure if anything on earth moves that fast!

It's like typing a laser pointer to a spinning motor and watching how fast the dot "moves across" a screen a few miles away. It'll be very fast* but it's not a miracle of engineering.

(*) Maybe even faster than the speed of light...!
 

Offline H713

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Re: True analog scopes
« Reply #256 on: December 21, 2022, 07:45:21 am »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

https://web.archive.org/web/20110926020847/http://www.oregonlive.com/silicon-forest/index.ssf/2011/09/a_tektronix_oscilloscope_that.html

But now at fast (but not exceptional) timebase of 20ns/div — get your calculator out to check me — the same beam is tracking horizontally at 500000 m/s, a horizontal line speed of more than 300 miles/second! And the thing that remains astounding for me is that it can repeatedly trigger and track the same groove on the screen, with calibrated speed and mm accuracy. Outside of a physics lab, I’m not sure if anything on earth moves that fast!

It's like typing a laser pointer to a spinning motor and watching how fast the dot "moves across" a screen a few miles away. It'll be very fast* but it's not a miracle of engineering.

(*) Maybe even faster than the speed of light...!


The fact that the beam can scan faster than the speed of light isn't an engineering miracle, but making it happen in at tube that is less than 30 inches long, and having it be readable with the naked eye is. The 7104 CRT (and the 7104 in general) is a true engineering masterpiece.
 

Offline tggzzz

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Re: True analog scopes
« Reply #257 on: December 21, 2022, 10:13:21 am »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

Oh, don't spoil tautech's assertion...

Which without some form of persistence is arguably of no use to anyone.

And definitely don't ask him how people with skill and imagination did and can use such equipment to make quite astounding advances.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline BillyO

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Re: True analog scopes
« Reply #258 on: December 21, 2022, 01:58:28 pm »
Well, it really isn't 'moving', so there's no limit, not even the speed of light.  A Tek 2465B can move the dot (mostly vertically) over 8cm in 700ps.   That's about 71,500 miles per second or ~0.4c.
The electric field is changing, but it it doing so very much further back in the beam where the rate involved is very much lower than the speed of light.
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Online Njk

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Re: True analog scopes
« Reply #259 on: December 21, 2022, 06:37:14 pm »
I think, to summarise this energetic thread, that ‘true analog scope’ aka CRO has for some time transitioned to heritage technology.

For those interested in heritage tech. Excellent free books about the USSR scopes (the nomenclature seems comparable to Tek and HP combined). Describes every related design house, lists all (as the authors claims) Soviet designs, and the post-Soviet scopes, up to 2019 I presume.

Now that company is behind the PicoScope brand so the information is from the horse's mouth.

The books are in Russian but there are a lots of images and it's not a paper scan so I think an automation can be used for translation.

https://eltesta.com/publications
 
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Online tautech

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Re: True analog scopes
« Reply #260 on: December 21, 2022, 07:31:00 pm »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

Oh, don't spoil tautech's assertion...

Which without some form of persistence is arguably of no use to anyone.

And definitely don't ask him how people with skill and imagination did and can use such equipment to make quite astounding advances.
With the all limited skill and imagination I could muster some years back I never found an easy way to get a waveform capture that was simple to take and quick to email, one of the primary reasons I assigned CRO's into the past. Even a manually initiated capture was far more advantageous to anything a CRO could provide let alone engaging a Single shot !

Experienced users might discount the need for captures as frivolous but they aren't to the novice as is proven by the numerous captures on this forum of those seeking help to understand what they see.
Here on the blog and some 20+ yrs later collecting screen captures with phones and uploading them is commonplace while substandard to having settings plainly visible on the display.

Those that haven't yet embraced DSO's are also unaware how user focus changes once some muscle memory develops your eyes rarely leave the display as settings are displayed there rather than need to have eyeballs walk around a CRO to arrive at how it was set up.
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Offline tggzzz

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Re: True analog scopes
« Reply #261 on: December 21, 2022, 07:38:06 pm »
I think, to summarise this energetic thread, that ‘true analog scope’ aka CRO has for some time transitioned to heritage technology.

Many CROs are actually digital/digitising.

(Cathode Rays are part of the output technology, whereas analogue/digitizing is the input technology).

Some Cathode Ray Oscilloscopes are both analogue and digitising, usually called "combiscopes" or similar.

Quote
So even if CRO is not for electronics any more, the concept, what was achieved with these machines, still worthy of respect. Might help explain why some of us still hang on to them.

All technologies have advantages and diaadvantages.

Newer technologies hopefully have advantages over older technologies. That doesn't mean older technologies are useless. Neither does it mean newer technologies don't have disadvantages.

Engineers should be capable of choosing the most appropriate (in a very wide sense) technology no matter what buckshot salesmen and managers utter, and should be able to make the best of whatever is available.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline tggzzz

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Re: True analog scopes
« Reply #262 on: December 21, 2022, 07:50:36 pm »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

Oh, don't spoil tautech's assertion...

Which without some form of persistence is arguably of no use to anyone.

And definitely don't ask him how people with skill and imagination did and can use such equipment to make quite astounding advances.
With the all limited skill and imagination I could muster some years back I never found an easy way to get a waveform capture that was simple to take and quick to email, one of the primary reasons I assigned CRO's into the past.

Wow. What a revealing assertion!

When not in my own lab using my own equipment, a camera is the fastest, simplest, and easiest way to capture a waveform. Imperfect example taken quickly under non-stop circumstances but one where the information has been admired by those interested in more than prettiness:


Even in my own lab, it is fast and easy!

Or are you unable to use a digital camera and attach a photo to email?! Is that beyond your imagination?!

« Last Edit: December 21, 2022, 07:55:50 pm by tggzzz »
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Offline tggzzz

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Re: True analog scopes
« Reply #263 on: December 21, 2022, 08:04:14 pm »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

Oh, don't spoil tautech's assertion...

Which without some form of persistence is arguably of no use to anyone.

And definitely don't ask him how people with skill and imagination did and can use such equipment to make quite astounding advances.
Those that haven't yet embraced DSO's are also unaware how user focus changes once some muscle memory develops your eyes rarely leave the display as settings are displayed there rather than need to have eyeballs walk around a CRO to arrive at how it was set up.

Those that have used digitizing scopes in anger for non-trivial measurements know:
  • many important settings are not shown on the display
  • the pain of chasing through multilevel menu to find/access a relevant setting
  • settings that are shown are often cryptic and difficult to understand, except by those familiar with the specific scope's display

It is easier, of course, if you are only selling using one manufacturers scopes. Most of us are using scopes from several manufacturers, each with their own GUI and quirks.

Personally I've only used HP, Tektronix, Digilent, Rigol digitizing scopes. I haven't used the ones you sell, Siglent; maybe they are perfect.
« Last Edit: December 21, 2022, 08:12:50 pm by tggzzz »
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Offline H713

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Re: True analog scopes
« Reply #264 on: December 22, 2022, 05:19:15 am »
Tautech does bring up a solid point, and what is IMO the MAIN reason to use a DSO over an analog scope, and that's the ability to capture single-shot events.

If you're dealing with anything that is pulsed, an analog scope is a PITA. Pulsed systems are all over the place now - power supply startup behavior, communication that happens in response to a user input (button push, etc).

You could use an analog storage scope. You could use a triggered scope camera. I sure wouldn't want to though...

And if you need to change the time base after taking the shot? Out of luck.




Also, let's differentiate between scopes with CRTs and analog scopes. The HP 54600 and Tek TDS380 both have CRTs, but have a lot more in common with a modern Siglent than they do with a Tek 465 or any other analog scope.
 

Online tautech

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Re: True analog scopes
« Reply #265 on: December 22, 2022, 07:12:08 am »
Tautech does bring up a solid point, and what is IMO the MAIN reason to use a DSO over an analog scope, and that's the ability to capture single-shot events.
Correction, to capture any event !

Greybeards just can't get their heads around this as they already know it all  ::) and never need to put a waveform capture in front of a mentor or here on the forum to seek advice/explanation of what they see.
All the skill and imagination of someone less experienced will never solve something they don't understand until that skill and imagination is gained from experience.
Which raise an old and valid question, which came first the chicken or the egg ?

Quote
If you're dealing with anything that is pulsed, an analog scope is a PITA. Pulsed systems are all over the place now - power supply startup behavior, communication that happens in response to a user input (button push, etc).

You could use an analog storage scope. You could use a triggered scope camera. I sure wouldn't want to though...

And if you need to change the time base after taking the shot? Out of luck.
100%
What today isn't pulsed in one manner or another ?

Quote
Also, let's differentiate between scopes with CRTs and analog scopes. The HP 54600 and Tek TDS380 both have CRTs, but have a lot more in common with a modern Siglent than they do with a Tek 465 or any other analog scope.
No, it's simpler than that as the main basic types of general purpose scope are just 2 types, DSO's or CRO's.
Some older CRO looking scopes are DSO's with a CRT display.

So just 2 main types, boat anchor CRO's with an analogue signal path through to the CRT display or the more capable DSO of which modern ones use LCD displays.
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Online tautech

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Re: True analog scopes
« Reply #266 on: December 22, 2022, 07:43:25 am »
The Tektronix 7104 can sweep faster than the speed of light, while at the same time being visible with a single sweep.

Oh, don't spoil tautech's assertion...

Which without some form of persistence is arguably of no use to anyone.

And definitely don't ask him how people with skill and imagination did and can use such equipment to make quite astounding advances.
Those that haven't yet embraced DSO's are also unaware how user focus changes once some muscle memory develops your eyes rarely leave the display as settings are displayed there rather than need to have eyeballs walk around a CRO to arrive at how it was set up.

Those that have used digitizing scopes in anger for non-trivial measurements know:
  • many important settings are not shown on the display
  • the pain of chasing through multilevel menu to find/access a relevant setting
  • settings that are shown are often cryptic and difficult to understand, except by those familiar with the specific scope's display
Skill and imagination resolves all these issues.
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Offline alm

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Re: True analog scopes
« Reply #267 on: December 22, 2022, 08:56:45 am »
Correction, to capture any event !

For repetitive events, you just take a picture of the screen. Which as tggzzz showed is also often the fastest on a DSO if you don't have connectivity set up beforehand. This technology existed then and it's even easier now.

What today isn't pulsed in one manner or another ?

Oscillators? Power supply ripple? Signals used in analog audio? Most kind of test signals coming from a function gen or pattern gen?

Also, many 'single-shot' events can be made repetitive (excluding destructive tests like nuclear fission tests). Drive the button input using a pulse train. Trigger the reset of a system using a function generator.

I have actually done that with a DSO just because it makes testing changes, like adding a cap, much quicker than manually resetting the test.

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Re: True analog scopes
« Reply #268 on: December 22, 2022, 10:01:41 am »
Correction, to capture any event !

For repetitive events, you just take a picture of the screen. Which as tggzzz showed is also often the fastest on a DSO if you don't have connectivity set up beforehand. This technology existed then and it's even easier now.
That's the thing with only using old equipment, you guys are missing out on so much capability now that memory is so cheap.
Not so much in the sub$1k bracket but many midrange save to internal memory if you don't have a USB stick installed. Then in menus so many seem to despise, within the File manager you can grab those captures remotely or transfer them to a later installed USB stick.
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Offline tggzzz

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Re: True analog scopes
« Reply #269 on: December 22, 2022, 10:04:37 am »
Tautech does bring up a solid point, and what is IMO the MAIN reason to use a DSO over an analog scope, and that's the ability to capture single-shot events.

If you're dealing with anything that is pulsed, an analog scope is a PITA. Pulsed systems are all over the place now - power supply startup behavior, communication that happens in response to a user input (button push, etc).

You could use an analog storage scope. You could use a triggered scope camera. I sure wouldn't want to though...

And if you need to change the time base after taking the shot? Out of luck.

Fully agreed. One-off events have always been the USP for storage scopes.

Analogue storage scopes always were a PITA, only used because there was nothing better. Early digitising storage scopes capitalised on that pain, even though they were suboptimum for other purposes.

Having said that, with analogue waveforms it is usually possible to make them repetitive. Less so with digital dignals, but you would normally use a logic analyser for those.

Quote
Also, let's differentiate between scopes with CRTs and analog scopes. The HP 54600 and Tek TDS380 both have CRTs, but have a lot more in common with a modern Siglent than they do with a Tek 465 or any other analog scope.

Agreed - again.

I find it sad that people who claim to know a lot about the subject deliberately continue to make that faux pas even after it is pointed out to them.
« Last Edit: December 22, 2022, 10:06:40 am by tggzzz »
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Offline tggzzz

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Re: True analog scopes
« Reply #270 on: December 22, 2022, 10:15:30 am »
Also, let's differentiate between scopes with CRTs and analog scopes. The HP 54600 and Tek TDS380 both have CRTs, but have a lot more in common with a modern Siglent than they do with a Tek 465 or any other analog scope.
No, it's simpler than that as the main basic types of general purpose scope are just 2 types, DSO's or CRO's.
Some older CRO looking scopes are DSO's with a CRT display.

So just 2 main types, boat anchor CRO's with an analogue signal path through to the CRT display or the more capable DSO of which modern ones use LCD displays.

Still confusing the front-end technology with the display technology?! Remarkable and sad.

H713 is right, and IMNSHO insisting otherwise doesn't increase your credibility.
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline tggzzz

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Re: True analog scopes
« Reply #271 on: December 22, 2022, 10:21:41 am »
Correction, to capture any event !

For repetitive events, you just take a picture of the screen. Which as tggzzz showed is also often the fastest on a DSO if you don't have connectivity set up beforehand. This technology existed then and it's even easier now.

What today isn't pulsed in one manner or another ?

Oscillators? Power supply ripple? Signals used in analog audio? Most kind of test signals coming from a function gen or pattern gen?

Also, many 'single-shot' events can be made repetitive (excluding destructive tests like nuclear fission tests). Drive the button input using a pulse train. Trigger the reset of a system using a function generator.

I have actually done that with a DSO just because it makes testing changes, like adding a cap, much quicker than manually resetting the test.

Spot on. Just so. Not difficult, really.

I don't think you'll get tautech to acknowledge that though. He has too much invested in believing otherwise.

(Having said that, I have had to fault-find a power-up problem that required a 6 hour off period for the problem to re-occur. To nobody's surprise a storage scope was highly beneficial in locating the source of that problem :) Right tool for the right job, and all that. )
There are lies, damned lies, statistics - and ADC/DAC specs.
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Offline baldurn

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Re: True analog scopes
« Reply #272 on: December 22, 2022, 05:03:48 pm »
Tautech does bring up a solid point, and what is IMO the MAIN reason to use a DSO over an analog scope, and that's the ability to capture single-shot events.

I feel this statement is so very wrong. The MAIN reason to use a DSO is every reason just about. You need to find reasons the other way around: is there still any reason at all to use or own an old analog scope?

One of the reasons stated in this thread is about beginners and poor people. The thing is that beginners absolutely do not want to get stuck with an old boat anchor. In the HAM community some older people do their very best to tell every newcomer that they need that old boat anchor. Luckily they usually fail and the new guy gets something much better. When pressed, this seems to be mostly about the old guys not wanting to learn about DSO or they have experience with some very old DSO that is nothing like a modern DSO.

I take part in a small maker space community with an electronic lab. We do some teaching, usually teaching other members. We do have some old analog scopes on the floor (donated to us) but nobody knows if these things even turn on. Why would we care? We have some Rigols and I recently got an Siglent SDS1104X-E + SDG1032X for the maker space, so we could do bode plots. I am not going to teach the new guy how to operate the boat anchor and then by the way, if you want to do bode plots, or thousand other things, you also need to learn the DSO. That makes no sense at all.

About poor people, in our area I would just recommend them to use our lab for free. Of course we live in a rich country. But for the guy that survives on 1 USD/day in Africa? - he sadly probably is not going to be very concerned about scopes at all. There is a very small pool of people that have enough to have a chance for learning and needing a scope, yet can not afford even a used DSO nor get access to free options. Especially students have options to use the facility of their learning institute with no costs.
 

Offline tggzzz

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Re: True analog scopes
« Reply #273 on: December 22, 2022, 06:03:54 pm »
Tautech does bring up a solid point, and what is IMO the MAIN reason to use a DSO over an analog scope, and that's the ability to capture single-shot events.

I feel this statement is so very wrong. The MAIN reason to use a DSO is every reason just about. You need to find reasons the other way around: is there still any reason at all to use or own an old analog scope?

That is a standard mistake in logical thinking. Just because X implies Y, it does not mean not-X implies not-Y.

In addition, your implication that people are advising not to use digitising scopes is incorrect.

Use a tool that satisfies the requirements. Analogue and digitising scopes are equally good at many important tasks.
« Last Edit: December 22, 2022, 06:07:48 pm by tggzzz »
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Offline baldurn

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Re: True analog scopes
« Reply #274 on: December 22, 2022, 06:20:59 pm »

That is a standard mistake in logical thinking. Just because X implies Y, it does not mean not-X implies not-Y.

I am not quite sure what you are trying to say with that. But if we must, the MAIN reason to use a DSO includes:

Single shot capture
Zooming on a captured waveform
Programable triggers of many kinds
Serial decoding
MSO
Statistics displayed on screen
FFT
Network connectivity
Programability by scripting / remote control
Much better display
Auto setup
Multiple acquisition modes
Math modes
Mask tests
Power analyses / other kinds of analyses
Bode plot

The list just continues. There is so much the analog scope can not do. Especially the analog scopes available cheaply.

On the other hand, the MAIN reason to use an analog boat anchor is:

NONE - for most of us.

Other reasons might be:

Analog scopes is the only thing I know and I do not need or wish to learn any of the new stuff
Analog scopes is what I got and I do not wish to spend any money
(Old) Analog scopes is a hoppy

And THAT explains why nobody is producing analog scopes anymore.
 


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