Analog versus digital oscilloscopes 2

[rauldm]

 think an advantage analog oscilloscope is for waveform with sweep I remember is nice to view it, I had a Tektronix  2247a, with 1 ms sweep rate the visualization is nice, if compared sweep waveform even with MDO3054 is better in analog oscilloscope, AM signals looks similar even in my low cost siglent with SPO tecnology. Finally I sold that scope for is big an heavy, measurements and cursors have poor accuracy.

I have  Tek MDO3054, TDS3012B agilent dsox2002a, siglent 1104x-e, GW GDS2202E all with DPO SPO or every name that's means Phosphor emulation, Also I have Scopemeter Fluke, this scope is not has phosphor emulation therefore waveform visualizaion is bad compared with analog scope.
Maybe low cost DSO and analog was a good combination when phosphor emulation was very expensive, but visualization performance for example in siglent 1104x-e is so good like TDS3012B, I think analog scope can works for comparing repetitives waveforms with DSO, non repetitive waveforms in analog oscilloscope is imposible, display is little compared with moderns DSO, is extremely limited on functions and triggers, I want an Iwatsu 7811 or lecroy 302 only for this propuse, but big size is limitation because takes same space a power supply and bench multimeter or waveform generator, are very noising, probe attenuation is other problem, only 10 or 100x with readout pin, arbitrary attenuation is imposible, active probing? imposible, some high frequency signals must be analized with active probe, pasive probe change drastically its impedance with high frequency even inside bandwidth.
Single shot function is impresindible for diagnostic or other specialized function, I only work in repair industrial and agriculture electronics, capturing for my is essencial, but all people has different needs, I think analog scope can be only optional, if space is not a problem, if you can buy a scope for a good price in work conditions can be good buy. up to 200 usd maybe 250 usd good price, near to 400 USD can you get a SDS1104X-E.

[Doctorandus_P]

First, is it even possible to buy a decent New analog oscilloscope anymore?
I had a look at the pintek site mentioned earlier, but they don't list prices, which is an instant dismissal for me.
When you look at "regular" sites (batronix, saelig, reichelt, welectron, digikey) then you can't even buy a decent analog scope anymore.
Digikey lists the Ownon AS201, which turns out to be a 20MHz single channel digital scope trying to mimick an analog schope (Why would anyone buy that for USD250?)

I did find:
https://www.conrad.nl/nl/p/voltcraft-analoge-oscilloscoop-ao-610-10-mhz-1-kanaals-122413.html
But that toy has only one channel, 10MHz and a screen so small it's just silly and with a price tag of EUR255 it's more expensive then an entry level digital scope, such as this (rebranded as) Peaktech scope for EUR220.
https://www.reichelt.nl/nl/nl/digital-speicher-oszilloskop-20-mhz-2-kanaele-peaktech-1402-p321524.html?&trstct=pol_6&nbc=1

Those bulky things have really gone the way of the dodo.

Talking about PRICE, a good Analog scope is MUCH better than a good Digital Scope.

I'm not sure what is the analog scope with the highest bandwidth, but up to 500MHz, a good analog scope will cost between 1/3 or 1/10 of a Rigol MSO5074 or Siglent SDS2104X Plus (hobbyist or officially upgraded) and 1/10 or 1/30 of a Tektronix, Keysight, Rohde & Schwarz, LeCroy, etc.

Comparing some 20+ year old analog scope to a new digital tektronix / keysight / R&S etc, is a quite silly comparison. Some people may be addicted to analog scopes, but the biggest market will be people with a tight budget, and there is a plethora of decent digital scopes starting around EUR 350, and those are a much better choice for beginners. DSO's just have too many advantages over those analog beasts to be taken seriously.

There probably is still a niche for people who really need 500MHz, but can't afford a DSO with that bandwidth, although you can get a 300MHz DSO below EUR 700.
https://www.reichelt.nl/nl/nl/digitale-oscilloscoop-met-geheugen-300-mhz-2-kanalen-rigol-ds2302a-p327496.html?&trstct=pol_0&nbc=1

[Kleinstein]

There are essentially not new analog scopes for a reason.  Even the entry level ($300-$500) DSOs are better than most analog scope excepts a few old high end models that can offer a little better BW than the cheap DSOs.
The XY mode is a bit weak with some DSO models, but it is rarely used anyway.
A used analog scope may still be available relatively cheap, if one can live with the limitations - with some experiance one can work around some, but not all.
Especially very slow signals and single/rare events is where an analog scope fails.

In the sub $100 range a used analog scope may be still atrractive over a cheap DSO with a tiny screen and often quite some limitations.

[vk6zgo]

There are essentially not new analog scopes for a reason.  Even the entry level ($300-$500) DSOs are better than most analog scope excepts a few old high end models that can offer a little better BW than the cheap DSOs.
The XY mode is a bit weak with some DSO models, but it is rarely used anyway.
A used analog scope may still be available relatively cheap, if one can live with the limitations - with some experiance one can work around some, but not all.
Especially very slow signals and single/rare events is where an analog scope fails.

In the sub $100 range a used analog scope may be still atrractive over a cheap DSO with a tiny screen and often quite some limitations.

In the early days of DSOs, relatively slow, but complex signals, like field rate analog video were their "Achiile's heel".

Long time/div settings reduced the sample rate to a few tens to hundreds of kHz, making them totally unuseable for a signal with 5MHz components.

Even when I first joined this forum, that was a limitation of some really cheap DSOs.

The really cheap "toy" things like DSO 138s & the like still offered, all suffer from that problem, whereas the litte analog referred to by Doctorandus_P still offers an honest 10MHz, even if it does look like something designed to be used by "Cabbage Patch Kids!"
It is, however, ridiculously priced!

If the thing doesn't actually lie to you, like the early, & the later "toy" DSOs, you can do useful work with the most basic of instruments.

[tggzzz]

Especially very slow signals and single/rare events is where an analog scope fails.

Except where you have an anaogue storage scope, preferably dual beam. But that is scraping the barrel; analogue storage scopes were a pain. (Having said that, I surprised at how much I don't dislike my Telquipment DM63!)

Single shot events always were the killer use case for digitising scopes. But for a long time the number of samples captured in a digitising scope was a real limitation, especially coupled with the lack of "peak display".

Nowadays a drawback for a beginner is the complexity of all the sampling and display modes which can drastically affect what you see/discover in a digitising scope. Doubly so when the config is hidden 4 levels down in a maze menu hierarchy.

[Doctorandus_P]

I browsed a bit around on Aliexpress, and some new analog scopes are still being offered. The 20MHz scopes cost about the same as their DSO counterparts and there even are some 100MHz CRO's, but they cost over EUR 700.

What finally does them in is the shipping of the big and heavy things. They're probably also a lot more vulnerable during shipping.
I've bought quite a lot of stuff from Ali, but I won't buy a scope there. Buying locally is about the same price (Even inclusive the 20% EU tax) and buying local gives you normal warranties and such.

[rstofer]

Nowadays a drawback for a beginner is the complexity of all the sampling and display modes which can drastically affect what you see/discover in a digitising scope. Doubly so when the config is hidden 4 levels down in a maze menu hierarchy.

Just like any analog scope, the important controls are V/div and t/div.  I suppose a few channel selections are important like 1x vs 10x but that's pretty easy to find.  Trigger controls are quite similar (which channel, trigger voltage).  One shot is different because analog scopes can't even do that (mostly).  But it's pretty simple!

All of the stuff buried deep in menus is related to advanced functions that analog scopes can't even do.  These settings can be easily ignored until the feature becomes necessary.  Maybe that comes up some day, maybe it doesn't.

I don't find the menu system of the Rigol DS1054Z to be all that complex.

Of course, the user could try the old fashioned approach and RTFM.  It's all there...

Incidentally, I have had a Tek 485 for nearly 20 years and I still don't know what all of the controls are for.  I do know where to find V/div, t/div and trigger threshold.  The other features just haven't been that important for me.  Other opinions will vary wildly.

ETA:  Don't overlook the 'Auto' button on the DSOs.  It will get a display on the screen.  Maybe some settings need to be tweaked, maybe not.  The purists will probably laugh at anyone professing to use the button.  Go ahead, laugh, I use it all the time because I don't always remember what I did to the setup when last used a few months ago.

[tggzzz]

Nowadays a drawback for a beginner is the complexity of all the sampling and display modes which can drastically affect what you see/discover in a digitising scope. Doubly so when the config is hidden 4 levels down in a maze menu hierarchy.

Just like any analog scope, the important controls are V/div and t/div.  I suppose a few channel selections are important like 1x vs 10x but that's pretty easy to find.  Trigger controls are quite similar (which channel, trigger voltage).  One shot is different because analog scopes can't even do that (mostly).  But it's pretty simple!

All of the stuff buried deep in menus is related to advanced functions that analog scopes can't even do.  These settings can be easily ignored until the feature becomes necessary.  Maybe that comes up some day, maybe it doesn't.

Not necessarily.

With an digitising scope I rapidly find the need to set it to "show me all samples not just the average, so I can see what is really there". I conjecture that many beginners haven't displayed the peaks, and so miss that the reason their circuit "isn't working" is that it is oscillating much faster than they thought possible.

Ditto finding how to set "show samples, don't draw straight lines between samples". I've seen the latter unnecessarily give very confusing and pessimistic display.

Basically I hate tools that attempt to "know what I need", because they always get it wrong one way or another. One bete noire is the fuel guage on my 1993 Toyota; there's an effin' computer between the sensor and the display. I park on a slope, and that means that it "reads low". I can deal with that. Unfortunately it doesn't read correctly when driving along horizontal roads - unless it has been parked on the flat for several hours. In the worst case it thoroughly confused itself, with the result that the car refulled itself while travelling at 70mph on a 5km bridge across the River Severn.

I don't find the menu system of the Rigol DS1054Z to be all that complex.

You can get used to any tool, even Windows

Of course, the user could try the old fashioned approach and RTFM.  It's all there...

An experienced user can do that; whether they do do that is a separate issue

But not beginners. They are rapidly overwhelmed by all the options, and don't have an internal conceptual framework for understanding why they are there nor when they would use them. The same is true for analogue scopes, but they are simpler and everything is "in their face".

Incidentally, I have had a Tek 485 for nearly 20 years and I still don't know what all of the controls are for.  I do know where to find V/div, t/div and trigger threshold.  The other features just haven't been that important for me.  Other opinions will vary wildly.

ETA:  Don't overlook the 'Auto' button on the DSOs.  It will get a display on the screen.  Maybe some settings need to be tweaked, maybe not.  The purists will probably laugh at anyone professing to use the button.  Go ahead, laugh, I use it all the time because I don't always remember what I did to the setup when last used a few months ago.

I don't laugh at auto; it is a more sophisticated variant of the "beam finder" button. I do dislike it leading to lack of thinking about what ought to be visible in the circuit.

[David Hess]

There are essentially not new analog scopes for a reason.  Even the entry level ($300-$500) DSOs are better than most analog scope excepts a few old high end models that can offer a little better BW than the cheap DSOs.

Performance has nothing to do with why DSOs replaced analog oscilloscopes.

Analog oscilloscopes depended on established technologies like electrostatic deflection CRTs and wide bandwidth high voltage vertical CRT amplifiers which do *not* benefit from increasing semiconductor integration.  These established technologies were as cheap as they were going to get.  DSOs were primarily limited by semiconductor integration for price and performance, which means they followed the geometric increase of integration just like computers did, resulting in low prices.

Early DSOs had a large cost premium over analog oscilloscopes, but some people were willing to pay it in selected applications where digital storage and processing was worth the cost.  Later DSOs were so cheap, because of increased semiconductor integration, (1) that they completely replaced analog oscilloscopes, whether they had better performance or not.

(1) Displays become cheaper also, and still are.

[David Hess]

With an digitising scope I rapidly find the need to set it to "show me all samples not just the average, so I can see what is really there". I conjecture that many beginners haven't displayed the peaks, and so miss that the reason their circuit "isn't working" is that it is oscillating much faster than they thought possible.

Ditto finding how to set "show samples, don't draw straight lines between samples". I've seen the latter unnecessarily give very confusing and pessimistic display.

Basically I hate tools that attempt to "know what I need", because they always get it wrong one way or another.

I think a display mode which duplicates the fidelity of an analog display but also highlights peaks is possible, but manufacturers consider only checklists of increasingly less important features, including maximum possible record length for a given investment in RAM, even if it lowers performance.  Customers purchase based on record length, and not human factors engineering.

[rstofer]

Of course, the user could try the old fashioned approach and RTFM.  It's all there...

An experienced user can do that; whether they do do that is a separate issue

But not beginners. They are rapidly overwhelmed by all the options, and don't have an internal conceptual framework for understanding why they are there nor when they would use them. The same is true for analogue scopes, but they are simpler and everything is "in their face".

Here is an EPIC thread where a new user buys a scope and then decides to test EVERY feature, one by one.  The link starts less than half way through the pages and there are a lot of pages but we cover a LOT of ground.  I had never used the scope to show the integral of a waveform.  What a trip!

https://www.eevblog.com/forum/beginners/what-an-oscilloscope-recommended-for-a-woman-passionate-about-electronics/175/

Charlotte buys a Siglent SDS1202X-E at post 150 (page 7) and it goes on for another 30 pages.

It IS possible to work through many of the examples in the User Manual without even having a signal source.  The compensation signal can be used for many demonstrations including the FFT feature.

[tggzzz]

Of course, the user could try the old fashioned approach and RTFM.  It's all there...

An experienced user can do that; whether they do do that is a separate issue

But not beginners. They are rapidly overwhelmed by all the options, and don't have an internal conceptual framework for understanding why they are there nor when they would use them. The same is true for analogue scopes, but they are simpler and everything is "in their face".

Here is an EPIC thread where a new user buys a scope and then decides to test EVERY feature, one by one.  The link starts less than half way through the pages and there are a lot of pages but we cover a LOT of ground.  I had never used the scope to show the integral of a waveform.  What a trip!

https://www.eevblog.com/forum/beginners/what-an-oscilloscope-recommended-for-a-woman-passionate-about-electronics/175/

Charlotte buys a Siglent SDS1202X-E at post 150 (page 7) and it goes on for another 30 pages.

It IS possible to work through many of the examples in the User Manual without even having a signal source.  The compensation signal can be used for many demonstrations including the FFT feature.

Charlotte was clearly interesting and exceptional. I encouraged her early in the thread, then others took over:)

I don't think she affects the basic points..

[tggzzz]

With an digitising scope I rapidly find the need to set it to "show me all samples not just the average, so I can see what is really there". I conjecture that many beginners haven't displayed the peaks, and so miss that the reason their circuit "isn't working" is that it is oscillating much faster than they thought possible.

Ditto finding how to set "show samples, don't draw straight lines between samples". I've seen the latter unnecessarily give very confusing and pessimistic display.

Basically I hate tools that attempt to "know what I need", because they always get it wrong one way or another.

I think a display mode which duplicates the fidelity of an analog display but also highlights peaks is possible, but manufacturers consider only checklists of increasingly less important features, including maximum possible record length for a given investment in RAM, even if it lowers performance.  Customers purchase based on record length, and not human factors engineering.

I wouldn't want to claim that analogue scopes have greater fidelity than digitising scopes. Different tools have differing advantages and disadvantages. Digitising scopes, arguably, offer more than analogue scopes, but that comes at t cost of simplicity and basic usability.

That basic usability is often ignored by some people.

[tautech]

Different tools have differing advantages and disadvantages.

They do and the differences for a similar type of instrument can be vast.

Digitising scopes, arguably, offer more than analogue scopes, but that comes at a/the cost of simplicity and basic usability.

This I take issue with as it's very wrong.
Analogue or digital, they all have a V/div, s/div control, brightness/intensity, graticule, and trigger level and slope all the basic things you need to display the simple repetitive waveform.
Yeah a DSO looks different so will the next car you buy. Scopes are tools that come in many different colors and sizes but they all do the same basic thing, display electrical waveforms.

That basic usability is often ignored by some people.

Only those that haven't engaged their grey matter and let what they see in front of them cloud their judgement to what the tool can do.

[tggzzz]

Different tools have differing advantages and disadvantages.

They do and the differences for a similar type of instrument can be vast.

Digitising scopes, arguably, offer more than analogue scopes, but that comes at a/the cost of simplicity and basic usability.

This I take issue with as it's very wrong.
Analogue or digital, they all have a V/div, s/div control, brightness/intensity, graticule, and trigger level and slope all the basic things you need to display the simple repetitive waveform.
Yeah a DSO looks different so will the next car you buy. Scopes are tools that come in many different colors and sizes but they all do the same basic thing, display electrical waveforms.

That basic usability is often ignored by some people.

Only those that haven't engaged their grey matter and let what they see in front of them cloud their judgement to what the tool can do.

You deliberately and explicitly ignore the extra complexity, and choose to concentrate on some simp!e examples that suit your point and purposes.

Not impressive.

[rstofer]

With an digitising scope I rapidly find the need to set it to "show me all samples not just the average, so I can see what is really there". I conjecture that many beginners haven't displayed the peaks, and so miss that the reason their circuit "isn't working" is that it is oscillating much faster than they thought possible.

In terms of getting dots versus vectors on the screen, it's a pretty easy button sequence (on the Rigol DS1054Z)

Press Display -> Type to set the waveform display mode to "Vectors" or "Dots".

No, I didn't know how to do it, never cared.  I just popped open the User Manual and searched for 'dots'.  The third hit was right on the money.  Didn't take even a minute.

Now, whether any dot is actually at the 'peak' is a different story.  But that's the problem with any sampling algorithm.  'Equivalent Time Sampling' comes to mind. If you have a lot of dots relative to the period of the signal, your chances of hitting the 'peak' are much improved.

[tggzzz]

With an digitising scope I rapidly find the need to set it to "show me all samples not just the average, so I can see what is really there". I conjecture that many beginners haven't displayed the peaks, and so miss that the reason their circuit "isn't working" is that it is oscillating much faster than they thought possible.

In terms of getting dots versus vectors on the screen, it's a pretty easy button sequence (on the Rigol DS1054Z)

Press Display -> Type to set the waveform display mode to "Vectors" or "Dots".

I've no reason to doubt that, but an equally valid counterexample is one I found on an otherwise decent and well respected HP series scope. There it was a couple of menus deep, and unforgivably reverted to the default when just about anything change.

When coupled with some other quite reasonable settings, the display was totally unrepresentative of the real world.

Complexity is something to be avoided as far as possible but no further.

No, I didn't know how to do it, never cared.  I just popped open the User Manual and searched for 'dots'.  The third hit was right on the money.  Didn't take even a minute.

Now, whether any dot is actually at the 'peak' is a different story.  But that's the problem with any sampling algorithm.  'Equivalent Time Sampling' comes to mind. If you have a lot of dots relative to the period of the signal, your chances of hitting the 'peak' are much improved.

There is no reason to believe an indicated peak is the actual peak, but that isn't too important. Analogue scopes have snalogous problems.

The point is that without something like the (appallingly named) peak display, a digitising scope actively conceals he complexity of reality+instrument.

[tautech]

DSO Peak detect and Persistence will display waveforms totally invisible to a CRO.

Go get a modern one and learn how powerful they really are.

[David Hess]

I wouldn't want to claim that analogue scopes have greater fidelity than digitising scopes.

I would claim it.  The proof is that the user can make a tangential measurement on an analog oscilloscope with just their eye to find a real RMS value in amplitude or time.  The display on an analog oscilloscope is a direct representation of a real otherwise difficult to perceive property.

One of the things I considered in my paper DSO design was displaying that RMS value as part of the display record of the histogram, instead of requiring the user to literally eyeball it.  If peaks are going to be highlighted on the display, then why not?  (1) Right now the only way a DSO can show part of it is with a gated RMS measurement.  (3) On the other hand it may be of questionable utility; how many users ever have a need to make a gated RMS measurement?  On the gripping hand, it does represent something real which is otherwise lost.

(1) Tektronix did something like this on one of their first DSOs, the 2232.  I think it works by applying a noise gate to the signal, but since it could not have been done during decimation, I am not sure how they got it to work as well as it did.  The result was removing the oscilloscope noise, while highlighting peaks.  Luckily it can be disabled, although it works surprisingly well.  (2) The photo below shows the impossible result.  I did not notice it at the time or I would have made recording with and without it enabled.  Ignore the vertical striping; that is a limitation of the 2232 display list processor.  I am using this as an example of display processing which either improves usability, or destroys, it depending on your point of view.

(2) I never saw this feature in another DSOs, by Tektronix or anybody else, so I wonder if Tektronix concluded later that it was a bad idea because it arguably makes the display less representative of what is really going on.

(3) High end DSOs can display a "slice" of the display histogram to reveal the distribution, but I do not remember seeing the calculation.

Different tools have differing advantages and disadvantages. Digitising scopes, arguably, offer more than analogue scopes, but that comes at t cost of simplicity and basic usability.

I do not think that tradeoff must be made, but some differences are for cost or space reasons, like having a single set of vertical controls for multiple channels.  Soft menu touch controls are cheaper than hard controls.

That basic usability is often ignored by some people.

I agree for the reasons I gave.