Question about analog oscilloscopes vs digital oscilloscopes - Page 1
Forum section: electronics / testgear

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 20, 2016, 02:45:44 pm
content: I've seen many videos about analog scopes but the one main thing that bugs me is about the sampling rate and how blind an oscilloscope is. Im not talking about digital scopes with cathode ray displays, i know they're awesome in their responsiveness.So if i have a variable wave coming in and i want to measure in real time to see changes (i dont want to store data) and put it through an oscilloscope, will a digital oscilloscope sample the wave continously or will it sample part of the wave instead? Would an analog oscilloscope show all the wave as its form and have theoratically infinite sampling rate?

author: nctnico
author_rank: Super Contributor
timestamp: June 20, 2016, 02:50:53 pm
content: Both an analog scope and digital scopes have blind time. Both will need to wait for a trigger before writing a signal on the screen. On an analogue scope with on screen cursors some time is needed to write the cursor information on the screen as well. All in all there is very little difference in blind time.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 20, 2016, 03:06:01 pm
content: So you're saying that even an analog scope that if i set to continuously measure a wave or basically spit out everything that comes into the input it will still have blind time?I get that there is a delay for things to get to the screen but shouldnt an analog scope work in less dependent way such that any input would get shown on the screen just the way it is + screen adjustments?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 20, 2016, 03:20:18 pm
content: Quote from: System Error Message on June 20, 2016, 02:45:44 pmAs nctnico said, every scope has blind time, there's no way around that. Analog scopes were pretty fast (up to 600k wfms/s) but that didn't compensate for the long list of shortcomings compared to a decent digital scope.QuoteWhat makes you think this is the case? In fact, pretty much the only real high waveform rate DSO with CRT screen was the HP/Agilent 54600 Series with MegaZoom ASIC, but the majority of the DSOs back then had much lower update rates (often in the 10's or 100's per second).QuoteA digital scope will sample continuously until the sample memory is full, and then wait for another trigger after which the cycle starts anew.QuoteNo, because even an analog has dead time (caused by the trigger circuit).

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 20, 2016, 03:22:06 pm
content: So other than a cathode ray display an analog scope has no actual benefit over a digital scope?

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2016, 03:39:59 pm
content: - Potentially lower noise floor - it has no bits so 'theoretically' infinite Y resolution.- No aliasing when the timebase is set too slow (potential trap for the unwary).- Easier to see mixed low and hight frequency signals eg. when you have mains hum superimposed on a faster signal.- Potentially faster to interpretIFyou're experienced with them ie. Easier to twiddle a few knobs by 'feel' to work out what's going on in a strange situation.- Absence of an Autoset button- (Edit:) You can do all sorts of 'magic' if you're long experienced with that type of scope (learned out of necessity). DSOs these days are easier for the normal user.

author: tggzzz
author_rank: Super Contributor
timestamp: June 20, 2016, 03:41:32 pm
content: Quote from: System Error Message on June 20, 2016, 03:22:06 pmAll tools have characteristics. Whether a particular characteristic is an advantage or disadvantage depends on the circumstances. One recent thread about scopes, for example, washttps://www.eevblog.com/forum/projects/5mhz-ttl-clock-oscillator-giving-20hz-what%27s-wrong/Ignore people that make absolute claims that X is better than Y. Take notice of people that give a balanced view of a tool's characteristics in different circumstances.If you want to stretch your imagination and capabilities, then imagine how you would developtest and measurea new tool such as the world's fastest scope. In doing that you will begin to appreciate that, with imagination and understanding, you can often use a relatively simple tools to do remarkable things; you don't always need the latest and greatest.

author: Keysight DanielBogdanoff
author_rank: Unknown
timestamp: June 20, 2016, 03:45:57 pm
content: I personally prefer the digital screen over the CRT because you have a lot more flexibility with persistence and more capabilities like cursors, automatic measurements, etc.Working with an analog scope has some unidentifiable draw though. But I'll invariably pull out a digital scope before an analog scope if I have to get stuff done.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 20, 2016, 03:54:51 pm
content: thanks for the info, im trying to compare how an analog scope performs compared to a digital scope in measuring an input signal when both scopes have equal frequency and digital has high sampling rate.So an analog scope would be better when measuring very tiny changes and over a large timebase because of no aliasing and theoratically infinite y resolution? It seems you can take a signal generator and use an oscilloscope to look like an arcade video game.

author: nctnico
author_rank: Super Contributor
timestamp: June 20, 2016, 03:59:37 pm
content: Quote from: System Error Message on June 20, 2016, 03:54:51 pmWhen using a DSO make sure to enable peak-detect and you won't have aliasing problems.

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2016, 04:01:44 pm
content: QuoteOh yes, you can make a lot of very pretty pictures (and hopefully still understand what's going on)!I should probably qualify my points with the statement that a DSO is better for pretty much everything else these days, but for these few items I still think and analogue scope excels.

author: guenthert
author_rank: Frequent Contributor
timestamp: June 20, 2016, 04:16:15 pm
content: Quote from: Wuerstchenhund on June 20, 2016, 03:20:18 pmWhat good will do me such a high update rate, unless I attach a (very) high speed camera to the screen? How unlikely a glitch will I be able to identify without burning away the phosphor with the periodic signal?I wonder whether there existed a device where an e-beam is projected on a narrow (quasi single dimensional) screen, deflected in one axis and a (long) film was moved continuously along the other? I'm sure it did, but how was it called (if it didn't exist, let me travel back in time, invent it and call it 'permascope') ?

author: nctnico
author_rank: Super Contributor
timestamp: June 20, 2016, 04:38:34 pm
content: Quote from: Gyro on June 20, 2016, 03:39:59 pmIf you forget about the fosfor being too slow to catch a lot of the spikes and non-linearities and distortion in the Y amplifiers. Don't forget the signal fed into an analog scope has to be amplified a lot before it has enough amplitude to drive the deflection plates.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 20, 2016, 06:28:16 pm
content: Quote from: System Error Message on June 20, 2016, 03:22:06 pmNot sure I would call a CRT a "benefit". I certainly won't miss the blooming, the flickering, the burn-in, the fragility and (on color CRTs) the often dreadful convergence problems of a fish bowl.As to the benefits of an analog scope, the only advantage I can think of is X/Y/Z mode. Almost all modern DSOs can do X/Y mode (and many do it nicely) but hardly any DSO does Z mode (brightness modulation) as well. In fact, the only digital scopes I'm aware of that can do that are the Rohde & Schwarz RTM/RTE/RTO scopes. Which is very likely because there is little demand for X/Y/Z mode these days.Quote from: Gyro on June 20, 2016, 03:39:59 pmBut it requires a lot of amplification of the original signal to get it to display on the screen, and that comes with added noise (which isn't necessarily visible on the CRT!), non-linearities and other issues.As to the resolution, it is only 'infinite' in theory because the CRT alone limits what can be displayed - and there are many things that an analog scope will hide from the user.QuoteTrue in general, but that comes down to knowing your kit, its limitations and what you're doing. And without that there are lots of traps that an analog scope offers which can easily mislead you.QuoteCan't say that this is true. A somewhat modern, decent DSO shouldn't have much problems resolving mains hum on a fast signal.QuoteNot sure how a graticule showing the waveform only on a CRT (analog scope) should be easier/quicker to interpret than a graticule with the waveform plus all relevant signal parameters shown on a color display.Also, interpretation by the user is pretty much the only way to get sensible information out of an analog scope, as there isn't a lot in terms of 'measuring (and even if there was, the poor specs of most analog scopes would make them of little use).Analog scope vs. DSO is like measuring voltage with a light bulb instead of a DVM.QuoteI guess you also frown upon computers with graphical user interfaces then?QuoteNot just easier, a decent DSO can offer a lot of information that is extremely difficult (best case) or completely impossible to gain from an analog scope.Analog scopes have been the mainstay of electronics for several decades simply because back then they were the best tools available, but technology has made a lot of progress in the last few decades which is why world & dog has moved on to DSOs. Most people that still use them either want them for their nostalgic feeling, because their knowledge about DSOs is still stuck in the late 80's or because they can't afford something better.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 20, 2016, 06:36:16 pm
content: Quote from: guenthert on June 20, 2016, 04:16:15 pmVery little (and frankly, these days we have better methods to find glitches than staring at a fishbowl).But then, the waveform update rate is generally overvalued anyways, and is so because a certain manufacturer that shall not be named has made update rates its main marketing argument. After all, high waveform rates are no longer the domain of analog scopes, in fact some DSOs vastly exceed the max waveform rate an analog scope can achieve.

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2016, 06:41:21 pm
content: QuoteI knew I would regret replying to this thread!I probably used the wrong words when I said " 'theoretically' infinite Y resolution" what I should have said was absence of visible steps (against an 8 bit scope anyway).

author: DimitriP
author_rank: Super Contributor
timestamp: June 20, 2016, 07:00:01 pm
content: Quote

author: guido
author_rank: Regular Contributor
timestamp: June 20, 2016, 10:36:21 pm
content: Turned into an analog vs digital discussion againObviously a digital scope has way more options, but an analog one could also get the job done, depending on what the job is. And i could not determine the job at hand.Quote from: System Error Message on June 20, 2016, 02:45:44 pmWhat is variable in this case? Frequency? Amplitude? Both? I'm assuming a wave is a sinewave (?). Are you sure you need a scope in the first place?E.g. if it is only amplitude you might be better off with a modern dmm with logging capabilities. Zero blind-time and a nice rolling graph (ok, you are blind inbetween samples but it is nothing like the blind time of a scope).As to the light bulb statement, i think the better comparisson is between an analog volt meter and a modern dmm. Where the dmm has peak hold, freeze, min-max, logging etc etc. But both can measure voltage. And if you want to track slow changes, the analog one might be better for the job. Or a digital one with a graph-bar next to digitsPS some analog scopes even have an auto setup button

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: June 20, 2016, 10:44:49 pm
content: Some scopes, like the Tek 2232, even have both a standard analog sweep AND a digital storage function (displayed on the CRT) with at least basic measurements like voltage, period, frequency, etc. It has averaging and peak detection as well.

author: tautech
author_rank: Super Contributor
timestamp: June 20, 2016, 11:00:16 pm
content: Quote from: guido on June 20, 2016, 10:36:21 pmYes they are DSO's with a CRT display.

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: June 20, 2016, 11:11:29 pm
content: Quote from: guido on June 20, 2016, 10:36:21 pmPretty sure that was the whole point of the thread? "Questions about analog oscilloscopes vs digital oscilloscopes"

author: nctnico
author_rank: Super Contributor
timestamp: June 20, 2016, 11:17:00 pm
content: Quote from: tautech on June 20, 2016, 11:00:16 pmGuido wasn't joking: the Tektronix 2445A comes to mind.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 20, 2016, 11:21:58 pm
content: Rather than permascope how about calling it a strip chart recorder.I am not sure what defines an oscilloscope. A box with some sort of programmable input, DAS and display? I would guess the dead time is not always going to be the case and more dependent on your requirements. For example, if you only needed a 1 hour sample rate, I am pretty sure I could get you something with reasonable sample jitter and store for a very long time with no dead time.Quote from: guenthert on June 20, 2016, 04:16:15 pm

author: guido
author_rank: Regular Contributor
timestamp: June 20, 2016, 11:35:16 pm
content: Yes, tek 24x5A or B. Or the last ranges of Iwatsu analog scopes.I know the question is about scopes, i'm wondering if that is the right question in the first place. For sure it was not the generic beginners question we see over and over. Were the answer is obvious.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 20, 2016, 11:54:46 pm
content: Quote from: guido on June 20, 2016, 10:36:21 pmAre you saying that a bench DMM with graphing capability has almost no blind time?By variable wave as in both frequency and amplitude.

author: rstofer
author_rank: Super Contributor
timestamp: June 21, 2016, 12:04:39 am
content: Quote from: System Error Message on June 20, 2016, 11:54:46 pmOf course a multimeter has blind time but it also has a capacitor for storing the peak voltage being measured. Then it takes quite a long time to convert the reading and display it.As to analog versus digital multimeters, the analog is clearly superior for seeing variations. My classic example is checking the voltage drop on a battery while the engine cranks over. The needle bounces around and while it doesn't give a quantitative result, it gives a very good qualitative result. Even with a bar graph, the DMM can't give a result anywhere near as useful.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 12:09:00 am
content: This is more about oscilloscopes rather. I was under the impression that a digital oscilloscope had much less blind time than a digital multimeter and that analog scopes and meters would catch any change.So it seems like an analog scope is pointless in the face of a good digital oscilloscope.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 21, 2016, 12:45:38 am
content: If you really need continuous sampling, as stated the DMM tied to a PC may work for you. Hard to say without some requirements. If you wanted to look at something slow like a car cranking current, seems like that would be simple enough to pull off. Even audio is no problem. Start getting into the tens of MHz, still doable. Hard drive space is cheap, add compression and some memory along the pipe... Who knows how fast/long you could sample without missing a beat.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 01:15:48 am
content: what i want to do is measure variances in a DC supply voltage when under various different loads. I want to learn to build an ultra stable DC PSU. One of the common causes of failures for something like a router (such as router freezing or not working) is almost always the PSU.

author: tautech
author_rank: Super Contributor
timestamp: June 21, 2016, 01:41:36 am
content: Quote from: System Error Message on June 21, 2016, 01:15:48 amThe correct tool for that job is a logging DMM.Generalisation:All scopes can easily display repetitive waveforms (to BW limits), that's their strong point and those with advanced trigger suites and high sampling rates, memory depth and wfms rates will allow some accurate logging if the user knows how to fully drive their scope. But mostly a DSO is a far more capable tool than a CRO.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 21, 2016, 04:06:20 am
content: Quote from: System Error Message on June 20, 2016, 03:06:01 pmNo,as well as a delay prior to triggering,there is also retrace time.The beam needs to return to the left side of the screen,& during that time,the CRT is blanked,so we don't see an annoying retrace line,just as is done with analog TV.Another thing that people forget,is that with normal multichannel analog 'scopes,there is only one beam.In order to show multiple displays,the channels are multiplexed------at long time/div settings,a "chopped" display can be used,with small segments of each applied signal appearing on the screen as the various channel displays,(sampling,in effect).At faster timebase settings,this runs into aliasing problems,so an "alternate" display is used.This displays one sweep of say,ch1,then one sweep of ch2,one sweep of ch3,one sweep of ch4 & so on.You can see that there is "blind time" in each case..

author: David Hess
author_rank: Super Contributor
timestamp: June 21, 2016, 04:51:00 am
content: Quote from: System Error Message on June 21, 2016, 01:15:48 amIf you are doing transient response testing of a power supply, then either an analog or digital storage oscilloscope will work fine; real time sampling is not even required. In theory a digital storage oscilloscope could use its FFT function to provide insight into the impulse response however you have to pay a lot for a digital storage oscilloscope which provides the necessary functions like differentiation and FFT phase unless you go with something old. If you are really interested in this, then the best option might be a USB oscilloscope from Syscomp Electronic Design which has built in VNA capability but you can do the same thing manually with any oscilloscope and a function generator.If you want to make RMS noise measurements, then oddly enough an analog oscilloscope might be better although the procedure is tricky; some DSOs have problems making RMS measurements on noise and at low signal levels. It is kind of weird that this is one place where I trust an analog oscilloscope more than a digital storage oscilloscope. It reminds me of the difference between a slide rule and calculator; with a slide rule I might only get 2 or 3 significant digits but with a calculator, it is easier to be off by multiple powers of 10. I assume high end DSOs have no trouble with this but it is not something I have had an opportunity to evaluate.A digital storage oscilloscope is definitely the thing to use if you want to watch for power glitches which could cause problems. In the best case, you can trigger on the digital reset or fail signal while recording the power supply output. This was one of the first things I used a DSO for 20+ years ago.None of these things require a high waveform acquisition rate.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 21, 2016, 05:09:55 am
content: Quote from: guido on June 20, 2016, 10:36:21 pmYeah, a thread titled "Re: Question about analog oscilloscopes vs digital oscilloscopes" turns in a discussion about analog vs digital scopes. Who would have thoughtQuoteYes, but your average analog scope doesn't really "measure" anything, it's pretty much down to the user's interpretation of the screen display. You have a course scale but together with the generally shoddy time-base stability and the limitations of the vertical stage you'll find in most analog scopes you're not getting much of precision out of it. So an analog volt meter, which can come with a precision scale and often reaches similar precision as a decent DVM, isn't a realistic comparison for an analog scope in my opinion.Also, not all DSOs are low-end/entry-level basic scopes. If you compare some mid-range or high-end analog scopes with their modern digital counterparts it should be clear why I said the analog scope is the equivalent of measuring voltage which a lightbulb, because there really is a world of difference. Most stuff you can do with even a good modern mid-range scope is simply not possible with an analog scope.QuoteWhy?QuoteIndeed, and some also have some very rudimentary measurement capabilities.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 21, 2016, 05:20:59 am
content: Quote from: System Error Message on June 21, 2016, 12:09:00 amExactlyYou have to remember that analog scope vs DSO isn't really the choice of two contemporary instruments, analog scopes are pretty much antiques, tools of yesteryear. All major manufacturers have given up making analog scopes more than a decade ago, simply because there was no longer a market for it. For a buyer of a new scope, there hasn't been a question of analog vs digital scope for a very long time. These days, even an entry level DSO from the big brands is vastly more capable and useful than any analog scope (and that is even true for most cheap scopes from China as well!), and if you go higher (mid-range, high-end) then you'll find scopes that actually are very sophisticated waveform analyzers which can give you a vast range of information that you simply can't ever get from any analog scope.Of course that doesn't stop some people spouting nonsense, like analog scopes being "high fidelity" or any such BS, and while some niches like the world of HiFi vodoo (aka audiophools) still prefer analog scopes (not because they are realistically better but because these groups consider everything digital as "imperfect") that doesn't mean that the sane part of the world hasn't moved on a long time ago.As I said before, would you buy a black & white TV today? The analog scope is pretty much the equivalent of the black & white TV when it comes to scopes.

author: DimitriP
author_rank: Super Contributor
timestamp: June 21, 2016, 06:28:23 am
content: QuoteThey have been rumors that some digital scopes have such a good display, it's almost as good as a CRT

author: guido
author_rank: Regular Contributor
timestamp: June 21, 2016, 07:47:23 am
content: Quote from: Wuerstchenhund on June 21, 2016, 05:09:55 amBecause it is easier to see slow changes on an analog voltmeter (this remark was about a voltmeter, not about a scope).So "ultra stable DC PSU". Ultra stable with regards to what?The voltage needs to be stable in 6 digits regardless of aging and temperature? Then you indeed need a logging DMM, a scope (analog or digital) is usesless.If you want to see dynamic behaviour (e.g. when you apply the load, what happens at that moment to the output), you need a digital scope. Which you trigger on that single event and it will show you this one moment. Discussing blind time is rather useless as it stopped sampling.So yes, i'm aware of the thread title and the initial question. But I'm still not convinced it was the right title and question.

author: tautech
author_rank: Super Contributor
timestamp: June 21, 2016, 08:00:36 am
content: Quote from: guido on June 21, 2016, 07:47:23 amQuite right if fast waveform details and time correlation are needed, if not a logging DMM with external trigger input will do the job.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 08:37:41 am
content: i am mainly trying to figure out if there would be any benefit to using an analog scope of similar frequency to a digital one. I gave the PSU as an example because its one of those components that have waves that can vary or have noise whereas measuring a digital signal would mean seeing the bits, any noises to them and their frequency.Whether the supply is AC or DC they have their waveform + variances + noises. DC being a straight line but when conditions change such as load, temperature the straight line isnt so straight anymore. Since the oscilloscope can measure voltage this also means you can than store and compare the outputs of different conditions.I still havent gotten my oscilloscope but i have been trying to learn how to use one and what can you do with it other than just seeing waveforms, been watching Dave's videos as well on how not to use one.What bothers me is that while you could log with a multimeter even DMMs have a sampling rate so when you're measuring voltage and amps i dont see how using a DMM would be better than an oscilloscope (comparing bench DMM to DSO). With digital oscilloscopes having USB and PC connectivity you could read the values from an oscilloscope instead.While analog scopes and meters are vintage and still useful i am trying to figure out if they are still useful even if you have a decent digital oscilloscope. So while analog scopes require someone with good eyes to take accurate measurements I would like to be able to bypass the DSO's buffer and use PC RAM instead to instantly save and store the measurements for things that it would be better for. Pretty sure DSOs are already good for many things i would like to get more use out of a bench oscilloscope. Having the oscilloscope be standalone unlike the analog discovery is nice but its also nice to be able to use the PC's resources to handle the load such as with math so i could combine the feature set and sensitivity of an oscilloscope with the computing power of a PC which you cant do with an analog scope.So other than measurements is there any sort of use or application in which having an analog scope of equal frequency to a digital one would be better? At the moment in the UK there hasnt been any cheap good used analog scopes like you guys get around the world or even in europe. Even buying the GW oscilloscope from Tequipment with the discount and add tax, import duty and shipping it is still much cheaper than buying it from the UK. So if it is worth the trouble i would keep an eye out for an analog scope not just in the UK but world wide.

author: ebastler
author_rank: Super Contributor
timestamp: June 21, 2016, 09:01:34 am
content: SystemErrorMessage, I am not entirely sure I understand your concern, but I think you may be worrying about a non-existing problem here.While DSOs do indeed sample the signal a discrete intervals only, there is always a low-pass filter at their (analog) input. So if an input signal has a very short spike, which falls in the middle between two sample time points, the DSO does not simply miss that spike. Rather, the low-pass filter will broaden the spike to a "bump" which has a low amplitude (since it is above the scope's bandwidth), but is many sample points wide. This will be captured by the DSO, and it will show up just like it would on an analog scope of comparable bandwidth.DMMs, of course, have a much slower sample rate -- by orders of magnitude. So they are no good if you are looking for fast glitches. But they have much better resolution: 14 to16-bit ADCs in a 4.5 to 5 digit DMM, whereas most scopes have only 8-bit ADCs. So you get much better amplitude resolution for small changes, at the cost of a loss in time resolution.

author: Gyro
author_rank: Super Contributor
timestamp: June 21, 2016, 09:16:05 am
content: Quote from: Wuerstchenhund on June 21, 2016, 05:09:55 amWell, if you don't know how to interpret the position of a trace against a calibrated graticule...Your average decent quality analogue scope, Tek etc. had *Specifications* for accuracy and linearity. The only difference between between a 3% accurate analogue scope and a 3% accurate DSO is that the DSO gives reassuringly precise looking digital readouts to lull the unwary into a false sense of security. On a typical 8 bit DSO you're looking at a resolution of 2 1/2 digits and that's before you even take the accuracy spec into account (7 digits at 2 1/2 digits display EDIT: assuming your waveform occupies the full ADC range)If you want accurate voltage measurements then use a DVM.The frequency and time measurements on a DSO are pretty good as they're derived from a crystal oscillator (f/w permitting). The only voltage readings really worth considering (above comments still relevant) are the ones attached to the cursors so that you can move them to where *you* think the various levels are, rather than trusting where the f/w thinks they might be.The only thing a scope (analogue or DSO) is good for is interpretation of waveforms - It you really think all those displays are giving you any sort of "precision" then you are sadly deluded.Any normal oscilloscope is a waveform interpretation tool. The DSO can obviously capture and freeze waveforms which is it's major advantage. The measurement readouts just come free with the f/w (you really wouldn't want to pay for them!).P.S. I just pulled out the instructions for my old Tek475A, a few specs:Vertical Deflection accuracy: Within 3% of indicated deflectionSignal delay between CH1 and CH2: 0.25ns or lessTrigger Jitter: Less than 0.2ns at 250MHzCalibrated sweep accuracy: +/-1% 5ms/div to 10ns/div, +/-2% 5s/div to 10ms/div (+/-2% when magnified to 1ns/div).Sweep accuracy degraded to +/-3% over -15 to +55'C temperature rangeNot quite the "generally shoddy time-base stability and the limitations of the vertical stage" that you were expecting maybe?

author: tautech
author_rank: Super Contributor
timestamp: June 21, 2016, 10:23:37 am
content: To quote the OP (SEM)QuoteThere is the problem....no scope experience.For his intended use:measure variances in a DC supply voltage when under various different loads. I want to learn to build an ultra stable DC PSU.At some point he will need a scope, pretty much any scope will allow him to see basic things like ripple, power on/off overshoot and switching spikes but he has a bit to learn of even basic scope use.A DSO will offer more capability, USB saved screenshots, captures (Single shot) and appropriate trigger settings to see/capture waveforms of interest all of which can be accomplished with very basic entry level DSO's.Name your brand....they'll all do it easy.Slow DC level transitions may be another matter, now you're in roll mode territory and small changes in levels may be more tricky to trigger on, this where channel V/div offsets might be handy and there's been recent threads on the traps for scope newbies.A DSO with an external trigger input may be of use if all channels are in use.@SEMBite the bullet, get a cheap DSO not CRO. Why?Screen capture, you'll find it invaluable as a scope newbie.PSI've tried to place a few keywords for you to Google for further understanding.Any scope usage measurement problem....start a thread and you'll have answers pronto.Check out the Tektronix website, they have some good tutorials and guides.Last but not least:https://www.eevblog.com/forum/beginners/oscilloscope-training-class-(long)/

author: tggzzz
author_rank: Super Contributor
timestamp: June 21, 2016, 10:31:03 am
content: Quote from: System Error Message on June 21, 2016, 08:37:41 amDepends on what you regard as "cheap" or "good".Two weeks ago I picked up a working 200MHz Tek475A+DM44 multimeter for £26 plus auction fees (and petrol to pick it up). (That's cheapandgood!)There's a Tek 475 going for £30, but you only have 2.5 hours to buy it.http://www.bidspotter.co.uk/en-gb/auction-catalogues/home-bpi/catalogue-id-home-a10243/lot-9fae1831-12f2-45ae-beda-a61f00ec20c2On Sunday I saw many scopes failing to sell at £30 at a hamfest. Personally I wouldn't regard them as good, but they would be a suitable vehicle for learning about scopes. Seehttp://rsgb.org/main/news/rallies/for local hamfests.

author: nctnico
author_rank: Super Contributor
timestamp: June 21, 2016, 10:33:51 am
content: Quote from: System Error Message on June 21, 2016, 08:37:41 amIMHO there is no benefit. 7 or 8 scopes ago I owned so DSO/analog hybrid scopes. These can be used as a DSO or an analog scope. Mine where always in DSO mode. I really wouldn't want to go back to using an analog scope.

author: Gyro
author_rank: Super Contributor
timestamp: June 21, 2016, 10:53:19 am
content: Quote from: System Error Message on June 21, 2016, 08:37:41 amYes, I'd probably go for the digital scope these days too as the good general purpose option. My point to Wuerstchenhund (or rather, rubbing his nose in it!) in my previous post is that it's completely wrong to push a DSO on the basis of the precision of its measurements. To take your PSU example, you need a scope to monitor it's noise level, turn-on, turn-off, load step response etc. But you need a decent DVM to check its accuracy and drift, a DSO simply can't do that.As tautech says, the DSO has the advantage in waveform capture etc.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 11:37:53 am
content: Thanks, so it means i wont have any use from an analog scope (not just for the use i am talking about). Going to see about getting a good bench DMM than or perhaps the analog discovery as it uses the PC instead of the built in CPU/RAM to do all the functions as it has 14bit DAC. So using both at the same time would probably be best.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 21, 2016, 12:03:38 pm
content: So the power supply was only an example and not something you need and you are more wondering if there is some place that an analog scope would be best suited. I think cost for the beginner may be one. The first oscilloscope I purchased brand new was a Hitachi. 100MHz, 4 channel, digital readout. I gave it away. After getting my LeCroy 7200, I never used it. You may find an old one no longer needed or in need of repair for free. Keep your eyes open.QuoteI admit that I am a sadly deluded person. A while back I made an attempt to see much I could ring out of one of my old scopes.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 12:56:52 pm
content: Quote from: joeqsmith on June 21, 2016, 12:03:38 pmYes im trying to see if an analog scope has any use when you have a decent digital scope. Otherwise i could spend the money for something else like the analog discovery or bench DMM or even the rigol DP832. measuring electricity will be one use i have in mind but i have many uses planned for an oscilloscope. Be rest assured i plan to use every feature possible for the fun of it but also to understand more about what goes on with these electrons.Ofcourse i plan to start with DC power output first because i want to make sure that my projects all will need some way to be powered other than always relying on bench PSUs, those things arent as portable nor do they come with DC input for solar. Sure i will use bench PSU when designing but after that if i have a solid PSU design i can just hook them up and use them after i finish. I would like to learn as much as possible with electronics which is why i focused on getting a decent DSO first as out of the available measuring tools a DSO is the most flexible and useful.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 21, 2016, 01:01:42 pm
content: 1: If you are doing any kind of electronics work or hobby other than the very most basic, you need an oscilloscope. The o'scope is the "King of Test Equipment" and no respectable workbench should be without one (at least!)2: If you are on a limited budget and cannot afford to spend at least 400-600 dollars US for a new-production DSO, then by all means look for an inexpensive, working, 2-channel analog scope in the 100 dollar range. It will serve you and teach you well while you save up your spare change, and when you eventually have enough to buy a digital scope you will appreciate it much more.3: If nothing else, you can use your new digital scope to help you repair your old analog scope if it breaks. The other way around... well, good luck with that.4: Low-end DSOs are not particularly good in x-y mode and rarely (like practically never) have a z-axis input capability. A nice old Analog scope can often do a much better job of x-y displays and can also help keep your laboratory warm in winter, especially if it is old enough to have a lot of valves (vacuum tubes) in it. For some special purposes a dedicated (and inexpensive) used Analog scope is hard to beat. See the scopeclock screens below, comparing the 400 dollar Rigol DS1054z DSO with the 125 dollar Tektronix 2213a analog classic.

author: Fungus
author_rank: Super Contributor
timestamp: June 21, 2016, 01:06:38 pm
content: Quote from: alsetalokin4017 on June 21, 2016, 01:01:42 pm5: Analog scopes fill up empty spaces nicely. If you think your workbench is much too big then analog is the way to go. DSOs are simply too small for this and not very stackable.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 01:10:01 pm
content: i already have a decent digital scope on its way, Im just trying to build my learning lab without having to spend too much. So if an analog scope is useless when i have a decent DSO than i can cross it out on the list so it can go towards getting other things instead.Other than the DSO and stuff i already have (that includes bench PSU) the stuff left on my list wasanalog scopebench DMMrigol DP832analog discoverya reflow soldering station like Dave mentioned in his tutorial video.Essentially none of these i need immediately for starting up. If there is no use for an analog oscilloscope when i already have a decent scope (which costed about $1000) than i can cross it out my list and get something else on my list instead that would be useful or maybe buy more capacitors for fun.Edit:Quote from: Fungus on June 21, 2016, 01:06:38 pmChallenge accepted, i will try to find some way to make my DSO stackable. Perhaps i could put it on my server rack or even on my desktop PC case.

author: tggzzz
author_rank: Super Contributor
timestamp: June 21, 2016, 01:10:59 pm
content: Quote from: Gyro on June 21, 2016, 10:53:19 amPrecisely. Overstated claims in one area bring into question the validity of claims in other areas.Use the best available tool for the job.

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 21, 2016, 01:13:23 pm
content: when the space is not enough to use an DSO + RMS Multimeter, use simply an analog scope

author: tggzzz
author_rank: Super Contributor
timestamp: June 21, 2016, 01:16:45 pm
content: Quote from: System Error Message on June 21, 2016, 01:10:01 pmDon't trust any tool too much. Use it, ensuring you work out where it is lying to you - and whether such lies are of any significant to you.Only after you havedeterminedthat the tools at your disposal are inadequate for your jobs, will you be in a position to know what you need next.Fundamentally, if you have to question the need for a tool, then you have already answered the question (you don't need it).

author: GK
author_rank: Super Contributor
timestamp: June 21, 2016, 01:55:04 pm
content: Analog oscilloscope technology, for all sakes and purposes, is as dead as the dodo, so some of the more strident pro-DSO zeal that invariably infects these threads doesn't come across as much lessthan anything posted by the other side.An analog scope has been mytraditionalgo-to instrument for any RF work (from LF to ~50 MHz) due to the freedom from aliasing and the ability to display AM and SSB modulation envelopes unmolested. It's taken DSO technology a long while to match the performance of analog in this regard, so if you're a HAM or a radio enthusiast procrastinating over which kind of secondhand shack scope to blow your limited budget on, the question of analog versus digital is still relevant. Just for example a $50 20MHz analog scope would serve you better for AM radio restoration than, say, Rigol DS1102CA.Suppose you want to view the SSB modulation envelope of a 20m (14 MHz) transmitter. Your modulation frequency is 400Hz. To view two full cycles (a period of 5ms) on the scope screen you'll need a horizontal timebase setting of 500uS/Div. To satisfy Nyquist, to resolve the 14MHz carrier without aliasing the sample rate must be 28M samples per second. That requires a memory depth of 5ms / (1/28M) = 140,000 points. Very few DSO boat anchors will do this.I've got a Rigol DS1202CA (200MHz, 2Gsa). It's completely useless for this kind of work (but that is OK, because this isn't what I bought it for). It's supposed to have a memory depth of 10k-points in single channel mode and 5k-points in dual-channel mode. Until this even I hadn't ever bothered to verify this claimed spec, but this evening just out of curiosity I tabulated the displayed sample rate for each timebase setting and calculated the memory points. This is in single channel mode and maybe I'm missing something because at no setting do I get 10k and it only does 5k on the lowest three decades.Some Tek 545B goodness for comparison:

author: tggzzz
author_rank: Super Contributor
timestamp: June 21, 2016, 02:21:11 pm
content: Quote from: GK on June 21, 2016, 01:55:04 pmErr. No. Provided you have a good sampler, you could sample that at 800Hz.How well would your DSO handle a QAM constellation diagram, especially with AGWN?Someanalogue scopes are famed for their overload performance, which is absolutely critical when looking at settling times. See Jim Williams for examples, of course!

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 21, 2016, 02:24:54 pm
content: you mean scopes like this?

author: GK
author_rank: Super Contributor
timestamp: June 21, 2016, 02:55:22 pm
content: Quote from: tggzzz on June 21, 2016, 02:21:11 pmClearly not what I was talking about. And no, the DS1*02CA series and a great many other DSOs do not have a "good sampler".How the Rigol renders a 400Hz 100% AM modulated 20m carrier, the only difference between the two screen shots is a slight variation in carrier frequency. If you carefully adjust the carrier frequency you can actually get a pretty reasonable looking static modulation envelope displayed, but that's a contrived test condition that has little relevance to real-world usage.EDIT: Ignore the frequency counter that's showing ~10MHz - it doesn't work properly at this timebase-to-frequency ratio.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 02:58:03 pm
content: Quote from: GK on June 21, 2016, 01:55:04 pmTypical engineer handwritingThanks though for the info, so it seems AM Radio still prefers analog scopes. I dont plan on doing AM or old TV radio but its good to know applications that prefer analog scopes.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 21, 2016, 02:59:12 pm
content: Quote from: System Error Message on June 21, 2016, 01:15:48 am*Rather than sitting there,waiting for a random different load to cause a variance,the logical thing is to switch in various loads,in a controlled manner while your DSO,CRO,or whatever is already operating.OK,you might miss the "one in a million " occurrence,but you will pick up the vast majority of problems.

author: nctnico
author_rank: Super Contributor
timestamp: June 21, 2016, 03:11:12 pm
content: Quote from: GK on June 21, 2016, 01:55:04 pmHint: peak detect

author: GK
author_rank: Super Contributor
timestamp: June 21, 2016, 03:12:09 pm
content: Quote from: System Error Message on June 21, 2016, 02:58:03 pmJust to be clear this is not outside the capabilities of DSO technology; just not the kind of DSO you're likely to pick up for the price of an old analogue boat anchor.

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 21, 2016, 03:29:56 pm
content: the old boatanchor scopes have still their place.When you make a mistake and put the hook in the high voltage you will understand that is sometimes better to use a glowing inputOf coarse the time of them is gone, but they are still useful and can help. I am collecting them, so I love to work with a 556 ...There are some specialities where modern DSO can get a problem to follow, by example: when your 545B is plugged with it`s 1A7 it will read 10µV/div. I want to see a normal DSO what can do that also.greetingsMartin

author: GK
author_rank: Super Contributor
timestamp: June 21, 2016, 03:35:27 pm
content: Quote from: nctnico on June 21, 2016, 03:11:12 pmIf the DSO has peak detect, yes, that may help. Incidentally, since I've never used my Rigol for this kind of thing I've never bothered to check/test if it has properly functioning peak detect. I just checked and it does and I am genuinely surprised at how well it works at resolving the above described modulation envelope, compared to what I've seen of other DSOs. Although the display update rate is crap and the resultant display is no where near as pretty when the modulation source is varying in amplitude rather than static.

author: Gyro
author_rank: Super Contributor
timestamp: June 21, 2016, 03:55:29 pm
content: Quote from: System Error Message on June 21, 2016, 01:10:01 pmAh, ok, I hadn't realised that you already had a (rather good sounding) DSO on the way. In that case you probably owe yourself a boatanchor Analogue scope anyway, firstly to see why it always provokes such heated argument, and secondly for the sheer joy of owning and using one.Clearly you should keep your spending priorities straight, but I wouldn't let that put you off keeping an eye out for a real bargain. As someone said, it's always useful to have a second scope for helping to fix the other one. From all your questions it's clear to me that you're desperately trying to find an excuse to get one anyway!If you have both, then you'll be ideally placed to take full part in the next heated debate... there should be another one coming along in about 3-4 weeks.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 04:38:57 pm
content: Well there are a lot of good advice and links in this thread. At least now i can totally ditch ebay which is very overpriced in the UK and very fake too. I havent used ebay for many months but since not only is the quality or legitimacy worrying but also they tend to be overpriced compared to other places. I even found electronics components from china much cheaper than ebay so while the quality and source may be the same at least the price is much less.Definitely looking forward to trying things and making sure i only blow up what im working on and not the scope or test meters. Is it safe to blow up electrolytic capacitors?

author: Fungus
author_rank: Super Contributor
timestamp: June 21, 2016, 04:49:44 pm
content: Quote from: System Error Message on June 21, 2016, 04:38:57 pmIt all depends on the size of the capacitor, the over-voltage, the available current...You probably won't die, if that's what you mean. Not unless you have a heart condition and die of fright from the bang. OTOH it can bereallyunpleasant; they make huge clouds of stink and fill the air with tiny bits of electrolyte-soaked paper that slowly settles all over everything in the room.If you ever manage to blow one indoors by accident you'll beverycareful around electrolytics after that - guaranteed!Edit: If the metal case hit you in the eye it could be nasty. I've seen a dent in a wall from quite a small capacitor that exploded.

author: nctnico
author_rank: Super Contributor
timestamp: June 21, 2016, 05:10:56 pm
content: Quote from: System Error Message on June 21, 2016, 04:38:57 pmNo. Blowing stuff up can go horribly wrong.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: June 21, 2016, 05:50:36 pm
content: Blowing up a selenium rectifier will leave your room smelling like garlic for weeks if not months.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 21, 2016, 05:58:29 pm
content: Quote from: System Error Message on June 21, 2016, 04:38:57 pm

author: guido
author_rank: Regular Contributor
timestamp: June 21, 2016, 06:41:11 pm
content: I've done that once with a tiny cap, which was in the wrong way around. Then you never do that again and check >three times if all is in the right way around. Now that you're starting to ask questions on blowing stuff up, i'm wondering how long your new scope will last.

author: robert_
author_rank: Regular Contributor
timestamp: June 21, 2016, 07:20:13 pm
content: Quote from: FlyingHacker on June 21, 2016, 05:50:36 pmWhat smells like garlic is mostly SeH2, which happens to be very toxic and it is best avoided to produce any of that (same applies to any Se compound).Quote from: Fungus on June 21, 2016, 01:06:38 pmDepends on the DSO. Modern low-end stuff is, but anything else is not exactly small. Both old and new, as soon as it gets anywhere mid-range or up, its gonna be large (which is good as it means a large display) and loud.6. Most analog scopes dont have a fan, and if they do its not as hugely loud.Now, my HP 1980B combines both analog and digital resulting in a device that is both analog and also hugely loud as it does have that 60mm 3-phase fan to blow out 200W of heat produced by approx. 2 square meters of PCB area packed incredibly full of THT components. It also has the digitizer option that can fill 512 poilts of storage in about 5 seconds with sequential sampling, or even single-shot at a few kS/s.Also it is the first analog scope to feature an incredibly crappy user interface, only to be exceeded in unusability by the first HP greenscreen DSO.

author: Jwalling
author_rank: Unknown
timestamp: June 21, 2016, 07:36:34 pm
content: Quote from: System Error Message on June 21, 2016, 04:38:57 pmAluminum cans are not so bad (depending on the size, of course) but wear eye protection! Tantalums on the other hand, get out the blast shield and fire extinguisher!Jay

author: robert_
author_rank: Regular Contributor
timestamp: June 21, 2016, 07:44:27 pm
content: Worst component to blow up IMO: these golden-coloured aluminium case 50-100W resistors. Resistance wire is wound around a ceramic rod, put into the thickwalled aluminium case and potted with some bakelite-like substance, which decomposed under overload and produces a very high pressure, until something BAD happens.At work we have the ceramic rod from one of these solidly embedded in the ceiling, missed someones head by just a few cm.Smelliest part: a can of expired surströmming in a campfire. Apart from that, polymer electrolytic capacitors (such as sanyo SEP). Small but stinks at least 26db worse than any regular electrolytic.

author: Jwalling
author_rank: Unknown
timestamp: June 21, 2016, 07:49:50 pm
content: Quote from: robert_ on June 21, 2016, 07:44:27 pmI must admit that I've never seen one of those blow up! IIRC Dale made those, yes?Jay

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 21, 2016, 07:53:28 pm
content: you guys are so enthusiastic, even more active than the computer networking forums lol, especially when it comes to tools, designs and blowing things up. Next thing we'll be discussing about buying uranium from amazon and enriching it.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 21, 2016, 07:56:26 pm
content: Quote from: guido on June 21, 2016, 07:47:23 amI see, I assumed this was about scopes not voltmeters. But no, that's correct of course.Quote from: Gyro on June 21, 2016, 09:16:05 am(Emphasis mine) Exactly, "interpret". Add to this the fact that the graticules on scopes are pretty coarse and on many analog scopes are sitting on a separate layer of glass or perspex which creates parallax errors and it should be obvious why you're unlikely to get more than pretty coarse results from it.QuoteWell, pretty much any serious test instrument has specifications, that doesn't mean they are not shit compared to modern gear.QuoteI didn't suggest you use a scope as a replacement for a precision DVM. But that doesn't change the fact that the analog scope relies on user interpretation, which is in general a pretty unreliable way to obtain results, especially in complex situations. This adds another layer of uncertainty on top of the already poor (by today's standards) specs of an analog scope.QuoteOn a decent DSO you don't use "read-outs" (cursors) for measuring standard parameters, you use the various measurement and analysis functions which actually use the sample data to derive the individual measurement results from. And at least on big brand scope that works pretty well and reliable, although on cheap Chinese B-brand scopes like Rigols YMMV of course (which isn't overly surprising when reading the "Yaigol" thread).I really only see people jumping to cursors when tasked with measuring standard waveform parameter is if they either don't know how to operate a modern DSO properly or the DSO they use is shit.But the frequency accuracy of a modern DSO is indeed pretty good (as are the various other parameters), even for cheap entry-level scopes, and magnitudes better than what the old analog critters offered (just look at the woeful specs of that Tek 475). Better scopes can also be locked to a high stability reference, which only improves the accuracy even further.QuoteOr maybe you need a reality check, because just because staring at a screen for glitches is all you know doesn't mean that's all there is. The fact that you assume that measuring waveform parameters on a DSO means "use cursors" tells me that your knowledge about DSOs is very likely stuck somewhere in the early 90's.QuoteFor you, maybe. Most time I spend with a scope is revolving around actually measuring stuff, i.e. signal variations, the various parameters you can find on non-monotonous waveforms, jitter, frequency composition, trending, deviation, you name it, and it's pretty much the same throughout the various labs I work in. Good luck deriving all these parameters from looking and "interpreting" a waveform.You really need a reality check re. what a decent and somewhat modern DSO is capable of. This isn't the 90's anymore.QuoteNo, it's actually as pitiful as I remembered it. If you think those specs are anything to write home about, then (borrowing your own words here) you're deluded.

author: Jwalling
author_rank: Unknown
timestamp: June 21, 2016, 08:00:58 pm
content: Quote from: System Error Message on June 21, 2016, 07:53:28 pmEspecially blowing things up!Quote from: System Error Message on June 21, 2016, 07:53:28 pmI've just reported you to Homeland Security!Enjoy your extended vacation in Guantanamo.Jay

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 21, 2016, 08:12:54 pm
content: the best blowing up is still a tantalum drop, not the stinky selenium rectifiers.I see that sometimes (in scopes)

author: Fungus
author_rank: Super Contributor
timestamp: June 21, 2016, 08:38:54 pm
content: Quote from: Jwalling on June 21, 2016, 07:49:50 pmThere's a lot of Chinese clones but the good ones are Dale brand, yes. Usually 1% tolerance.I've got a couple of 1 Ohm 1% Dale resistors for use as current shunts.I can't imagine what it take would to burst that thick aluminum case (but I'll bet it makes some noise when it happens!)

author: Fungus
author_rank: Super Contributor
timestamp: June 21, 2016, 08:39:59 pm
content: Quote from: Jwalling on June 21, 2016, 08:00:58 pmNo need. The NSA was already on it.

author: Gyro
author_rank: Super Contributor
timestamp: June 21, 2016, 09:51:17 pm
content: @Wuerstchenhund, it's pretty clear that we're not going to converge completely on this one. You have a pretty emotive way of putting things, and please remember that I was responding specifically to your 'lightbulb vs DVM' comment.Please remember also that I have already suggested to the OP that a DSO is his best option at this point.To cover your points:QuoteYou're implying worst possible case here. Since we're talking decent scopes, any decent analogue scope in the last 40 years has used a CRT with internal graticule - there is no parallax error. The only exceptions would be things like vectorscopes with oddball graticules but we're talking scopes here. With a standard 8x10cm graticule, each major division represents 12.5%, so it is pretty easy to read to the 3% accuracy figure. You might argue that the trace might not be scalable to full screen height, but the same applies when a DSO when the full bit depth of the ADC isn't in play.QuoteI've just scanned through the current Keysight offerings. Vertical accuracy seems to be pretty universally stated at 3% until you get up to the 10 bit Infinium-S series where it drops to 1%. At this point you're well outside the pocket depth of 99% of people reading this forum. 3% is exactly the same specified vertical accuracy as the Tek 475A.... 3% is 3%, you can't call one of them shit without calling both of them shit! I suspect that you don't want to do that.QuoteWell you did say "Analog scope vs. DSO is like measuring voltage with a light bulb instead of a DVM"Sure, open to interpretation, but with the parallax issue dismissed and the 'poor' vertical specs being equal to the DSO's then it comes down to the user's ability to read the screen. What this does do however is constantly remind you of the accuracy that the scope is capable of, the digital readouts can imply greater accuracy than the scope is actually capable of achieving.QuoteUnfortunately most people reading this thread probablyareusing Rigols.Relying on the f/w to correctly identify min/max/peak/overshoot etc. on all waveforms is a bit of an act of faith, and any scope can suffer a bug. I agree that with the ultimate scope you wouldn't need to use the cursors.QuoteI already said in my reply that the timing accuracy of a DSO is bound to be good (it damned well ought to be) due to its crystal clock.QuoteNot true actually.Ok, I'm playing devils advocate a bit here, I've already said that DSOs are pretty much superior in all respects these days. But goaded by your 'lightbulb' comment I felt the need to demonstrate that in terms of vertical accuracy (what else would you use a DVM...or a lightbulb for) they are both pretty much the same, andbothare pretty poor in DVM terms.

author: nctnico
author_rank: Super Contributor
timestamp: June 21, 2016, 10:07:06 pm
content: With all the signal processing capabilities of a DSO (high resolution, averaging, and -if you are lucky- input filtering) you can clean up a signal nicely so it is easier to make cursor measurements but in many cases I just let the scope's measurements do the work.

author: egonotto
author_rank: Super Contributor
timestamp: June 21, 2016, 11:16:29 pm
content: HalloDavid Hess wrote:"If you want to make RMS noise measurements, then oddly enough an analog oscilloscope might be better although the procedure is tricky"How can this done???Best Regardsegonotto

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 22, 2016, 09:27:15 am
content: Quote from: Gyro on June 21, 2016, 09:51:17 pmProbably not. That's life.QuoteFTFY. I have no emotive feelings towards scopes or T&M gear in general. Having grown up on analog scopes, I certainly understand the fond feeling many hold for this type of scopes, but from a practical POV that's irrelevant.What I do find annoying though is when people who look for a scope get recommendations to go for an analog scope instead of a DSO, usually with some outdated or just simply incorrect BS attached to it (and we had some really good stuff in this regard in other threads, like claims that analog scopes are "high fidelity" instruments). All this does is cause some disappointment and (worst case) monetary loss with the poor soul asking the question.Analog scopes had their place back in the day, but the reality is that these days have long gone. Nowadays an analog scope is an antique, nothing more, and it should really not be peddled as if it was an alternative to a DSO, because it really isn't. An analog scope might be a good buy if you're completely broke and get one in fully working condition for $50 or so, or if you're into nostalgia and antique test gear, but aside from these niche cases it's pretty much just a waste of money.QuoteI'm fully aware of that, although I still have the feeling you miss the main point of this comment, which is that an analog scope (a tool you correctly said is for looking at waveforms) doesn't give you any numbers, similar to a lightbulb which doesn't give you numbers for a voltage (although an experienced lightbulb user may well interpret the brightness level to get a reasonably close figure of voltage). A DSO however does give you numbers, pretty precise ones (within its specified accuracy of course).QuoteYes, I'm implying non-perfect cases here, simply because non-perfect cases come up more often than expected in real life.And while I agree that many newer analog scopes have their graticule in the CRT glass, there are still many scopes around that haven't.Also, I didn't say parallax error is a major issue, or that all analog scopes are affected. At the end of the day, it's just one of many properties that increase uncertainty.QuoteYes, the vertical accuracy for an 8bit DSO is 3% but that's just one of many spec data points, and for others like linearity or horizontal accuracy the difference much bigger. Just look at the time base specs of your average analog scope, it's performance specs are shit even when compared to a bottom-of-the-barrel scope like a Rigol DS1054z (and Rigol hasn't exactly shown stellar engineering when it comes to the oscillating parts in their scopes). And for an instrument that was ultimatively designed to show or measure voltage changes in the time domain, a stable time base is pretty essential. The only reason it's not much of a problem on an analog scope is because results are generally dependent on user interpretation, which introduces even higher uncertainties than the poor specs of the scope itself.And as to the voltage accuracy of an DSO, many better 8bit DSOs offer high resolution/ERES modes which increase the vertical resolution to 10 or more bits (for example, R&S RTE/RTO scopes go up to 16bit), which is a viable way to increase vertical accuracy if the loss of bandwidth that comes with it is acceptable.QuoteThe number of Rigol threads could certainly suggest that, but I'm sure there is a very large number of people here that use something else. There are certainly a lot Agilent/Keysight users (DSO6k/7k, DSOX2k/3k, some Infiniium 548xx/8k/80k/9k users) here, a fair number of Tek users, and even a few R&S and LeCroy users, plus an increasing number of GW Instek users.QuoteUsing measurements on a DSO isn't a leap of faith, not much more as using any other function of any test instrument is (how sure can you be that your analog scope is still within even it's lacklustre specs, unless of course you fully calibrate it everytime before using it in anger?). Of course there can be bugs, but DSOs with automatic waveform paremeter measurements aren't exactly a new thing (even the old LeCroy 9400 from the late 80's could do that), and at least with the big brands that is generally reliable.But as someone who only superficially follows the various Rigol threads I can't say how mature the measurement functionality in Rigol scopes is, but personally I wouldn't touch a product, which at the end of the day is supposed to be a test instrument you want to rely on for your measurements, is thrown to market with such a large number of bugs and with the hardware idiocracies listed in the "Yaigol" thread. But I understand that the low price tag can be very tempting.

author: Nozzer
author_rank: Contributor
timestamp: June 22, 2016, 10:11:03 am
content: As someone whose had an analogue oscilloscope for years and am now looking to go digital, I'm astonished that anyone would consider an analogue over a digital scope. I've been equally astonished over the past few months what one can do with even a basic digital scope.I am a little baffled why digital scopes seem to have no chop button though, and what is all this about auto buttons, help buttons etc.....

author: Gyro
author_rank: Super Contributor
timestamp: June 22, 2016, 10:19:18 am
content: @Wuerstchenhund,Ah, more convergence than I thought then. I certainly welcome the transition from "shit" to "lacklustre"Yes, I've similarly gone through the evolution of test instruments from the fairly distant past to their current level of development.I think we're coming down to an educational information here, given the many recommendations for certain 'low grade DSOs' there is a tendency to see those magical digits on the screen as 'gospel' (I understand that some do have some f/w issues with AC measurements).I think the very large disparity between horizontal and vertical performance (something that didn't occur in analogue scopes) is part of the 'problem'. In an ideal world the displays would be maybe 7 or 8 significant digits of horizontal (timing related) measurements and 2 1/2 to 3 digits (yes you can do some clever stuff to squeeze a bit more) for vertical. Of course that would look silly, so horizontal readings get squeezed down and vertical ones pushed to the max. Of course this disparity also has relevance for slope measurements.When I'm doing audio stuff I use a low bandwidth 16 bit scope. Yes it has uV resolution and a noise floor of -125dB but I still have to remind myself occasionally that for all its 16 bits of resolution it still only has a Y accuracy spec of +/-1%. This remains a trap for the unwary (or uninformed).Just to inject a bit of controversy still, browsing through the rest of the 475A's specs, its Y section and trigger circuit performance does actually stand up pretty well in the modern world, even if it does lack the ADC and readouts.

author: tggzzz
author_rank: Super Contributor
timestamp: June 22, 2016, 11:02:30 am
content: Quote from: Wuerstchenhund on June 22, 2016, 09:27:15 amI agree, with the proviso that some people make similar un-nuanced OTT claims for DSOs.For example...QuoteThere are a few technical applications in which specific analogue scopes are still better than some DSOs, as has been mentioned elsewhere on this thread. There are many more cases where they can do the job just as well as DSOs. And as you note, some people (especially on this forum) can't afford a new scope.QuoteNonsense. OK, it doesn't spoonfeed you with digits, but the numbersarethere for the moderately intelligent. Or, if you aren't sufficiently intelligent to determine the numbers, then you aren't intelligent enough to use a scope in the first place!QuoteParallax has the benefit that it directly and visibly has to be understood. OTOH, it is very difficult to spot and correct problems with DSOs internal algorithms.You acknowledge that in...QuoteSo, it appears that your "DSOs are always best" kind of statements are implicitly presuming that the DSO is actually a high-end professional-gradeexpensiveDSO from a reputable manufacturer. In that case I probably wouldn't argue. Neither would I argue that a new Rolls Royce isn't better than a second-hand Ford Escort.But a Ford Escort will probably get you to your destination just as well - and much better if you can't afford a Rolls Royce! That's the kind of balance and nuance missing from your statements.

author: tggzzz
author_rank: Super Contributor
timestamp: June 22, 2016, 11:05:50 am
content: Quote from: Gyro on June 22, 2016, 10:19:18 amMy "IBM" 475Adoeshave readouts for voltage, resistance, time and frequency. And a nice <2ns risetimeSince it is surplus to requirements, how much do you think I can sell it for

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 22, 2016, 11:18:18 am
content: Quote from: Gyro on June 22, 2016, 10:19:18 amWell, you can put lipstick on a pig, but it is still a pig.QuoteI agree, but that pretty much comes down to people not knowing how to properly use the scope (which includes being aware of its limitations!), and this is a completely different (albeit still important) problem that has nothing to do with analog scope vs DSO.And while the analog scope in general lacks any (potential misleading) numbers, it comes with its own set of traps that in the past have even cought out many experienced engineers.QuoteThe voltage accuracy of a normal 8bit scope isn't much of an issue for most tasks (as you said correctly, a DVM is a better tool to measure voltage accurately), but the timebase accuracy is for a device that covers the time domain.QuoteTrue, but again, being aware of the limitations of your test gear is completely unlrelated to the topic (analog vs digital scope).QuoteNot sure about the Y section (*cough* linearity plus a glooming tube *cough*) but Tek's analog scopes come indeed with a great trigger performance, much better than contemporary HP scopes. It's a real shame Tek never really made the jump into the digital world, as their digital scopes have been mediocre at best.But I guess it only shows that what was great yesterday isn't necessarily something to write home about today.

author: Gyro
author_rank: Super Contributor
timestamp: June 22, 2016, 12:37:29 pm
content: Quote from: Wuerstchenhund on June 22, 2016, 11:18:18 amJust for curiosity's sake. Vertical linearity (displayed) less than 0.1 div. error at the centre of the screen vs upper and lower extremities. I make that <1.25%. Ok not stellar but pretty darned good for the complete analogue gain chain and electrostatic deflection using distributed Y plates in a high PDA tube (clever chaps in those days!). I'm not actually sure how that would compare with the linearity of the input amps and an 8 bit flash ADC, it's not a widely touted figure in DSO specs. You'd probably have to go to the ADC datasheet. ...and yes it's a real shame that Tek didn't manage to translate all that skill into the digital age.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 22, 2016, 02:41:40 pm
content: Can your low-end digital scope do this?(Stable display of two waveforms at different frequencies)

author: rstofer
author_rank: Super Contributor
timestamp: June 22, 2016, 03:17:15 pm
content: Quote from: alsetalokin4017 on June 22, 2016, 02:41:40 pmI must misunderstand the question... But, yes, I can push 4 digital signals that are binary submultiples into my DS1054Z and get a stable display. That's kind of the point.I don't have a source of two frequency related sine waves (and they have to be related if the display is to be stable) but I would expect the scope to work the same as it does on square waves.If there's a bigger question that I missed, I'm interested in knowing what it is. I have a lot to learn about DSOs. My vast 5 weeks of experience isn't all that extensive!

author: Jwalling
author_rank: Unknown
timestamp: June 22, 2016, 03:19:24 pm
content: Quote from: alsetalokin4017 on June 22, 2016, 02:41:40 pmAre they asynchronous?Does this count? (Single trigger mode - does yours do that?)EDIT: They are asynchronous...Jay

author: tggzzz
author_rank: Super Contributor
timestamp: June 22, 2016, 04:10:33 pm
content: Quote from: Gyro on June 22, 2016, 12:37:29 pmConfirmed on my 465, 475 and 485.Clearlysomeoneis comparing very good+expensive X with poor+cheap Y, and declaring X the winner. Some might argue that shows ignorance. In any case it is unimpressive - and completely unenlightening. I'm not a scope fetishist, honestly. I'm only going to keep the 485, so consider the 465 and 475 "on the market"

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 22, 2016, 04:20:30 pm
content: Quote from: rstofer on June 22, 2016, 03:17:15 pmNo, the signals I showed on the 125 dollar (used of course) Tek 2213a are _not_ related, or synchronous or binary submultiples. In fact they are coming from two different sources altogether. That is the point.The scope is using Vertical Mode triggering, hence it is triggering alternately on either channel.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 22, 2016, 04:22:28 pm
content: Quote from: Jwalling on June 22, 2016, 03:19:24 pmAnd how much did that scope cost? Although since the "high end" of DSOs can run to half a million dollars, I suppose anything that costs less than a new car could be considered "low end" for DSOs.

author: nctnico
author_rank: Super Contributor
timestamp: June 22, 2016, 04:43:38 pm
content: Quote from: alsetalokin4017 on June 22, 2016, 02:41:40 pmThe GW Instek GDS2000E has no problem with showing 4 different totally unrelated frequencies using alternate triggering. I used that feature recently BTW. I doubt it's little brother the GDS1000B series starting at less than $400 will have problems doing that as well.

author: Jwalling
author_rank: Unknown
timestamp: June 22, 2016, 04:58:29 pm
content: [quote author=alsetalokin4017 link=topic=69974.msg967824#msg967824And how much did that scope cost? Although since the "high end" of DSOs can run to half a million dollars, I suppose anything that costs less than a new car could be considered "low end" for DSOs.It's a TDS784D. New I think about $34K in 2000 or so. Now you can get them for $800 to $1200 US or so on Ebay. Even a TDS744A can do this; maybe $600.Jay

author: alsetalokin4017
author_rank: Super Contributor
timestamp: June 22, 2016, 05:01:29 pm
content: Quote from: nctnico on June 22, 2016, 04:43:38 pmThe GDS2000E series is of course quite a bit more expensive than what I'd call "low end".I don't see anything in the GDS1000B operator's manual that indicates it has alternate channel triggering capability.http://assets.tequipment.net/assets/1/26/Instek_GDS-1000B_Series_User_Manual.pdfHappy to be corrected if I'm wrong.

author: nctnico
author_rank: Super Contributor
timestamp: June 22, 2016, 05:54:48 pm
content: Quote from: alsetalokin4017 on June 22, 2016, 05:01:29 pmPage 107 of the manual says alternate trigger mode so you have to be corrected

author: tggzzz
author_rank: Super Contributor
timestamp: June 22, 2016, 06:48:53 pm
content: Quote from: alsetalokin4017 on June 22, 2016, 02:41:40 pmThis is of course true, but in how many circumstances is it useful? I've always regarded alt and chop modes as being a poor workaround for a lack of two beams - and that's dual beams/samplers is preferable.

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 22, 2016, 07:12:20 pm
content: 714L (disconnected, it makes me tired. The 7844 do the job better)But the internal display is greatful, better then the monitor.

author: Jwalling
author_rank: Unknown
timestamp: June 22, 2016, 08:16:14 pm
content: @Martin.MCan't see what's going on there...Jay

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 22, 2016, 08:37:48 pm
content: hello Jay,this may be one of the scopes what are better then the old analog scopes.But in the time I have the right setup on the DSO my analog is finished with the test..So that instrument have nothing to do, the analog scope is always runningI am to old for a change. The 400MHz Dual Beam will continue, its enough for home use.greetingsMartin

author: CustomEngineerer
author_rank: Frequent Contributor
timestamp: June 22, 2016, 11:53:52 pm
content: Quote from: alsetalokin4017 on June 22, 2016, 02:41:40 pm$250 Hantek DSO5072P can do this.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 23, 2016, 02:33:16 am
content: In early 90's I was properly introduced to the world of DSOs, and that wonderful HP54600 (IIRC) was beyond anything I could ever dream - obviously unattainable for the common hobbyist. Fast forward a few years and I finally got my own oscilloscope, an analog Kenwood CS4025 (20MHz, 2 ch) at the incredible "bargain" of US$800.00 - not the HP, but my workhorse for 15 years. During this time I drooled over the low cost Tektronix TDS1000 series, but starting at about US$1000.00 it was still a bit steep for my hobbies - not to mention the analog was much more responsive.In 2012, due to the eevVBlog's curse, I got the DS1102E at the unimaginable price of only US$400.00! I thought I was done with the analog, but after a while I still felt it was lacking the analog feel that my trained eyes were accostumed. However, the other advantages surpassed my old analog by a huge margin. It was not until Dave's review of the newly launched DS1054Z and its intensity grading that I felt a DSO would really make me feel at home again. I ended up getting a bigger guy (DS4014) at a bargain, although not in the same league as the other two, but this feature finally helped me put the analog at rest.This whole story is only intended as an example of how things have to evolve technically and financially to overcome the hump between two discerning technologies - also, for hobbyists like me the financial plays a larger role. I think that in the 90's Tektronix did that with their low-cost monochrome DSOs and, in recent years, Rigol has done that for two generations with their DS1000 and DS1000Z series.All in all, get an analog if you feel like playing with older tech, get the feel of observing the waveforms and require the extra bandwidth at a reasonable price. If you are working mostly with digital electronics, I would definitely recommend the DSO.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 23, 2016, 03:17:47 am
content: Quote from: tggzzz on June 22, 2016, 06:48:53 pmReal "dual beam" Oscilloscopes had the disadvantages of cost,circuit complexity,bulk,& in many cases,limited display size,so were not suitable for general use.Multiplexed channels using "chop" & "alternate" displays suited most purposes,& were more commercially viable.Cossor made a big thing of "true dual beam" instruments,but that advantage couldn't maintain sales against 'scopes which outperformed them in all other areas,& could even supply four "multiplexed" channels.Even Cossor tossed the dual beam CRTs & went to multiplexing eventually.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 23, 2016, 04:27:18 am
content: Quote from: rsjsouza on June 23, 2016, 02:33:16 amIn the early 1990s,HP & Tektronix came to my then work (a TV Studio),to show us their "latest & greatest" DSOs.I had seen a very early 1980s HP DSO which displayed a field rate PAL signal as a mess of random spikes like my untended back lawn,but I assumed the newer ones would be much better,so was as enthused as everybody else.Unfortunately,field rate displays (around 4 div at 5ms/div)were still useless,due to aliasing.The things had very little memory,so they dropped the sampling rate,until at that time/div setting,it would display simple waveforms only.Even PAL line rate displays were very poor.The Reps thought we were all "dinosaurs" because we weren't awestruck,& trotted out the script they were given,about it "being an equally valid way of looking at waveforms" etc,although that had nothing to do with the context of our misgivings.They came back in successive years,until the DSOs "almost" made it,but they gave up after that.We eventually got our first DSO---as a replacement for an analog Tek one which was a total "lemon".It had driven Tektronix to despair,so they were glad to do the swap.This DSO wasn't bad,------it saw field rate signals OK,but its sample rate at those settings interacted with the 4.433 MHz colour subcarrier,so it showed a non existent low frequency noise signal,which luckily could be disregarded.When we bought a new Oscilloscope for the Transmitter site,however,it was a 200MHz analog Iwatsu.We found the UIs on both Tek & HP 1990s instruments to be tiresome in the extreme,with often used functions needing to be accessed from menus.The UIs on modern DSOs have converged towards that of analog 'scopes,with many functions available as individual controls on the front panel,making the learning curve between CRO & DSO & vice versa much less steep.Modern DSOs of the DS1054z class & above can also handle complex signals at long time/div settings without aliasing problems.

author: tggzzz
author_rank: Super Contributor
timestamp: June 23, 2016, 07:02:32 am
content: Quote from: rsjsouza on June 23, 2016, 02:33:16 amThat's a balanced assessment, which seems reasonable.However, I'll put an alternative scenario for the last paragraph based on:there are very few digital systems; photon counting and femtoamp circuits come to mind. All other systems are analogue systems where the receiver(s) interpret the analogue signal by slicing it into two values. If the analogue input violate the requirements in any way (see data sheets), then the sliced value will be incorrect. That is summed up as "signal integrity", and is a bigbigproblem for professionals (with large and/or fast circuits) and amateurs (who don't understand inductors and transmission lines)modernjellybeandigital circuits such as a 74lvc1g04 can switch 5V into 50ohms in <1ns, i.e.significant spectral output above 500MHz, which that does get transmitted and (hopefully) received30MA/s and 5GV/s transitions; yes, megaAmp and gigaVoltaffordable, by people on this board, scopes often fall into two camps: old 400/500MHz analogue scopes or new 100MHz scopesGiven that, a sound development strategy is to:use a scope to ensure analogue signal integrity;onlya scope can do thatuse any means (including a scope) to debug the logical operationA modern 100MHz scope simplycannotdo the first, whereas an older analogue scope can. Neither scope isnecessaryfor the latter, although both are very helpful.Given a modern fast (and expensive) DSO vs an old analogue scope with the same bandwidth, I'd probably choose a DSO. If, like many people, I couldn't afford such a DSO, I would prefer to settle for the faster analogue scope.I wouldn't bother withany20/50MHz scope unless I was interested in audio or mechatronics or switch on/off transients. For the latter, a DSO is the only option.I wouldn't buy an analogue storage scope, although if one was available, I'd use it occasionally.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 23, 2016, 11:18:51 am
content: vk6zgo, although I haven't worked professionally with analog baseband video signals, I completely understand the frustration with the DSO's attempt at digitizing and displaying them. I think this particular application was one of the last entrenched fields where analog oscilloscopes were absolutely a breeze to work with. I don't have a DS1000Z, but I have a hunch it will still not display these signals with the proper level of detail required. I played a bit with my DS4014 but unfortunately early in my experiences my video source (a cheap DVD player) bit the dust and I haven't had time to get another one and start over. As far as I could tell the DS4014 was very promising in displaying the waveforms, but it is not really an entry level hobbyist oscilloscope (it is not a high end one either).

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 23, 2016, 12:13:15 pm
content: well this post is enlightening, so basically for an ASO vs DSO of the same frequency the ASO still has some uses (few or niche) and cost less perhaps? lets take the human interpretation of the screen values and storage/recall functionality out of the equation and compare basically the scopes of same frequency. So a DSO will do everything an ASO except not as well for a few areas but better in other areas. If anyone who owns many scopes just like as seen in EEVBlog videos could comment that would be helpful.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 23, 2016, 12:20:12 pm
content: tggzzz, thanks for your comment. I confess my last paragraph was written a bit in a hurry as I was already tired of writing my post on a tablet - obviously by digital systems I meant a sliced and quantized simplification of our analog world, not true discrete systems such as the photon counter.Your approach to solving problems is what I usually recommend as well. That is in fact one of the most thoroughly discussed points around here: DSOs (especially the earlier generations) may oversimplify the real world while giving psychologically reassuring absolute measurements that may trap users of all ages (that is also why I cautiously specify logic analyzers to entry level hobbyists).On the other hand, I don't think a typical hobbyist will need to be concerned about timing issues with sub nanosecond transitions in his/hers Arduino or Launchpad. If that is the case, a 500MHz analog scope will be a bit better to display the waveform but will lack the convenient features of even entry-level DSOs. If that doesn't cut it, you would then have move higher in the food chain and find a new and high maintenance love...I agree the sale price for a higher bandwidth analog scope (a 2465A or B, for example) is still averaging around US$200 on eBay US - attainable for hobbyist work but somewhat of a gamble given the age of these instruments. That also tips the scale for a brand new DSO despite their limitations and (sometimes) unpolished design.I also agree with you: given the choice of similar specifications I would go for the DSO, although an analog scope is incredibly useful when compared to nothing - and no, Wuerstchenhund, it is not like a light bulb versus a DMM but exactly like a VOM versus a DMM (sorry, I couldn't resist)

author: tggzzz
author_rank: Super Contributor
timestamp: June 23, 2016, 12:46:11 pm
content: Quote from: System Error Message on June 23, 2016, 12:13:15 pmAllclasses of instrument (e.g. scope vs spectrum analyser, or analogue vs digital), types of instrument (e.g. Tek7603 vs Tek465), and individual instrument (your Tek 485 vs my Tek 485) have differences that can trap the unwary. That's doubly true when RF is considered, i.e. anything above, say, 50MHz.That's whyengineers/technicians(i.e. not hackers) should learn their relative merits, and ensure they are aware of their limitations.And then choose the right tool for the task at hand. Frequently several tools are adequate for any given task.

author: tggzzz
author_rank: Super Contributor
timestamp: June 23, 2016, 01:43:18 pm
content: Quote from: rsjsouza on June 23, 2016, 12:20:12 pmIn many logic circuits the shortest important time interval is the hold time, and that's independent of the clock period. The Arduino's ATSAM3X8 GPIO pins have a setup+hold time of 3ns. Even my wimpy 16MHz Arduino Trinket (ATTiny85) has 4ns transitions (i.e. 1000MV/s), so noticable frequency components at 90MHz.A 100MHz scope (3.5ns risetime) is barely adequate. An RPi might well be faster.And then if there is any other logic hanging off the GPIO pins, that will determine the speed. My measurements indicate that a jellybean inverter (74lvc series) has transition times of around 700ps; certainly less than 1ns.QuoteSometimes temptation istoohard to resist

author: oldway
author_rank: Super Contributor
timestamp: June 23, 2016, 06:26:05 pm
content: Quote from: tggzzz on June 23, 2016, 07:02:32 amIn my opinion, CRT technology is at his best up to about 200 Mhz.Above this range, sophisticated technology must be use as distributed deflection plates, micro-channel plate (MCP) and meshless box lens CRT.CRT's with post accelerator voltage is far better. This is used in oscilloscope above about 30 Mhz.I don't like storage CRT's, that's a too sophisticated technology, not good at all.But for measuring switch on/off transients, you can use a long decay phosphor CRT.I have an old Philips PM3233 dual beams with a long decay phosphor for this use.For digital electronics, there is no match between DSO and analog oscilloscope...DSO is the winner, no doubt about it.An analog scope can still be useful for analog electronic, power electronic, repair, and hobbies.

author: nctnico
author_rank: Super Contributor
timestamp: June 23, 2016, 07:16:29 pm
content: There is no such thing as digital electronics. It is all analog. I also don't see how an analog scope is good for on/off transients. A DSO with a reasonable amount of memory you can capture a single shot and zoom in on all the transient details you like. This is especially handy if the transient is likely to cause damage or difficult to repeat (like examining arcing in a relay).

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 23, 2016, 07:38:54 pm
content: no question, the DSO is the perfect way to check transients.In the old time that was made with a 7104 and a mounted polaroid camera.Today I cannot buy fresh films for the camera, so this become history. Only when you have not the money for a 1GHz DSO, the old 7104 will come back to do the job for lessAnd analog storage scopes was mostly not fast enough to make that good.But go in a music studio to repair a analog mixer desk with a very lot of channels (I have to do that sometimes), there is nothing faster then a batterie operated µTek ( Type 213 ), of coarse a full analog scope, ground free, with a very accurate DMM what will read directly from the hook voltages and signal levels. Every thing have it`s favorite place.modern DSO have only 2 problems: 1.) they are too much expensive and 2.) no easy repairgreetingsMartin

author: JPortici
author_rank: Super Contributor
timestamp: June 23, 2016, 07:48:01 pm
content: as if all the teks that are worth having didn't have unobtanium parts

author: oldway
author_rank: Super Contributor
timestamp: June 23, 2016, 08:23:25 pm
content: Quote from: nctnico on June 23, 2016, 07:16:29 pmWith a long persistence CRT, one can see a transient even in single shot.It's not as comfortable as with a storage oscilloscope, but it is possible, in particular to verify that there is no transient at power on/off of a power supply or to measure startup overcurrent.Behaviour of PID can also be verified as you can use a low frequency input signal. (1 or a few Hz)As to check the voltage across an arcing contact, I do not advise a lot to do this because it's a great way to destroy your oscilloscope input attenuator and amplifier.Just provide either a free wheeling diode (dc voltage), a RC and MOV (ac voltage) on the inductive parts.I work with power electronics and I have never needed to verify that with the oscilloscope.I sometimes feel that some people work in reverse: they want to invent unnecessary uses to justify the resources of their measuring equipment.

author: nctnico
author_rank: Super Contributor
timestamp: June 23, 2016, 08:31:16 pm
content: Quote from: oldway on June 23, 2016, 08:23:25 pmJust wait until the question ends up on your plate! And no, there wasn't a simple answer for the problem at hand.

author: oldway
author_rank: Super Contributor
timestamp: June 23, 2016, 08:38:34 pm
content: Quote from: nctnico on June 23, 2016, 08:31:16 pmAnd what help using an oscilloscope in this case ?You know the contact is arcing....You don't have a lot of solutions...choose the right relay or contacts, eliminate all LdI/dt, reduce the nominal voltage, reduce the current, use a 2 stages off circuit, ....And even if I should have to measure overvoltage on arcing contacts, I should use the MAX function of my Fluke 87V instead of an oscilloscope. It is far more secure.

author: nctnico
author_rank: Super Contributor
timestamp: June 23, 2016, 08:52:22 pm
content: Quote from: oldway on June 23, 2016, 08:38:34 pmThe question in this case was: how much can a particular relay handle and is it possible do something to make it handle more. This information was necessary to create an economically optimal design for a mass produced circuit which also needed to be absolutely reliable. Using a DSO was essential to get screenshots of what kind of voltages and currents are flowing during arcing; I literally cooked a few relays during these tests so repeatability at the limits was hard to achieve. I can't go into much details (NDA) but it was an interesting thing to measure and just using a DMM would not have been sufficient to get all the information I wanted.BTW A differential probe is an easy way to isolate the scope's inputs from circuits misbehaving.

author: AR
author_rank: Contributor
timestamp: June 23, 2016, 09:55:47 pm
content: Hello nctnico,I this relay testing for breaking DC or AC voltage across the contacts.

author: oldway
author_rank: Super Contributor
timestamp: June 23, 2016, 10:49:48 pm
content: Quote from: nctnico on June 23, 2016, 08:52:22 pmFor me, your explanation is nonsense.First rule to have an "absolutely reliable" equipment is to use parts below specifications of the manufacturer (max ratings)."How much a particular relay can handle", no need to worry, that's technical specifications of the relay." is it possible do something to make it handle more"...for sure, not, you cann't use it above it's max ratings in a "absolutely reliable" circuit.You also forget that in a"absolutely reliable circuit", you must choose a security factor for max current and max voltage.

author: oldway
author_rank: Super Contributor
timestamp: June 23, 2016, 11:07:13 pm
content: Quote from: AR on June 23, 2016, 09:55:47 pmProbably DC as AC is far easier to interrupt.I worked with electrical cabinets with relays and contactors interrupting 250Vdc...It was a nightmare even with 3 contacts in serie.

author: David Hess
author_rank: Super Contributor
timestamp: June 23, 2016, 11:15:37 pm
content: Quote from: System Error Message on June 21, 2016, 12:56:52 pmQuote from: System Error Message on June 21, 2016, 01:10:01 pmSince you already have a DSO on the way, I would consider an analog oscilloscope superfluous unless it fulfills a specific but general need like high bandwidth. No DSO feature can make up for lack of bandwidth when it is needed. What is the least expensive new DSO with 350 MHz or more of bandwidth?There have been a few times where I have used an analog oscilloscope to do things that few or no inexpensive modern DSOs could do but the situation is rare enough to be generally ignored. Examples include reliable wideband RMS measurements, alternate triggering (some inexpensive DSOs can do this), displaying small snivets, and large range offset measurements.QuoteI have never had a problem stacking my DSOs as illustrated by this photograph although currently in that spot I have a 2232 analog/DSO stacked on a 2247A analog oscilloscope which has considerable automatic measurement capability. Also in reference to alternate triggering which I *have* found to be useful in the past, you could always buy two separate inexpensive DSOs which is sort of what I ended up doing although not for that specific reason.

author: nctnico
author_rank: Super Contributor
timestamp: June 23, 2016, 11:17:25 pm
content: Quote from: oldway on June 23, 2016, 10:49:48 pmThe reason is simple: because I can't give out all the details to make sense of it all. You just have to accept that from other people on a forum every now and then.The point however is that I needed to make measurements on a non-predictable system which is where a DSO in single shot mode really shines. Capture once and study the event in detail with the help of long memory and zoom. An added bonus is the ability to make screenshots with cursor measurements and math traces to put in a report.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 24, 2016, 12:09:11 pm
content: Quote from: tggzzz on June 22, 2016, 11:02:30 amIn short, it solely relies on user interpretation. Thanks for confirmingBesides, I wouldn't exactly consider clinging to yesteryear's test gear a sign of intelligenceQuoteNo, it isn't, at least not if you have a rudimentary understanding as to what's going on.QuoteNo, I don't. In fact, people were pretty quick identifying the various bugs in their Rigol (or Siglent) gear. The issue wasn't identifying the bugs, the isse was that the products in question were clearly not mature enough to be released, and the slow response of the manufacturer in fixing the bugs.QuoteNo, my "these days investing money in anything else than a DSO is silly" kind of statements are implicitly presuming that the DSO isn't made by some crappy B-brand which regulary releases products full of bugs but by a reputable big brand. That neither implies "high-end" nor "expensive", unless you consider entry-level scopes like the R&S HMO1200 or Keysight DSOX2000 "high-end". Or an old HP 54600 Series scope for that matter, which despite being roughly 20yrs old, still tops most analog scopes. And these scopes regularly go for a couple of hundred dollars these days.Also, let's talk about prices. That Tek 475, which actually*was*high-end back then, did cost around $1700 in the mid-70's, that's roughly $10k in today's money. The broad base of scopes however weren't 200Mhz high-end scopes, these were mostly simpler models in the 20Mhz to 60Mhz range, with generally inferior specs. A lot of them were pretty shit even when they came out, like some of the USSR made low end scopes that were sold under various names around the globe, or (as a younger example) the various analog scopes made by GW Instek, Atten and other outfits.What that means is that even what once was a high-end analog scope has already difficulties keeping up with a somewhat decent entry-level DSO. Now imagine how much worse the other crop of analog boat anchors compare against them.I've seen a lot of scopes throughout the decades, and even back then in the analog scope days not everything was great, and these old scopes didn't get better now that they are antiques.QuoteJust that the equivalent to the analog scope isn't a Ford Escort, it's pretty much horse and buggy, and (like the analog scope) it lacks all technological achievements made that are available in its successor, i.e. powerful brakes, heating, crash-safe body, occupant restraining systems, rubber tires, electrical lighting, cruise control, stability and tracktion control, on-board entertainment systems, satnav, whatever (like the analog scope's lack of even the most basic measurement and analysis capabilities, or even very basic stuff like proper storage). And I'm not sure horse and buggy can generally be seen as a viable means of transport these days.The Escort equivalent would be an earlier DSO like the HP 54500 Series, because like the Escort it can pretty much do all the basics that are expected from a car today, it just comes with inferior performance (acceleration, economy, crash performance) and lacks most of the options that are available in newer cars (ESP, ABS even depending on the model, side airbags, pre-crahs warning and so on), and it looks old.But, and this is why car analogies are seldomly appropriate, I'm not sure a new DSOX2000 can be considered the equivalent of a Rolls Royce (that would be something like the Keysight DSO-Z or the LeCroy LabMaster, both scopes that come with a 6 digit price tag). A modern day entry level DSO is more like cars like the Skoda Fabia, VW Up or Dacia Sandero.Anyways, I know we're unlikely to agree on this, but at the end of the day that doesn't matter. The fact is that the analog scope is dead, period. All major manufacturers have stopped producing them, most of them a long time ago (Iwatsu held on for longest due to contractual requirements to keep them available). There hasn't been any new development in analog scopes in more than two decades, and there won't be any new models coming out. It's dead, period. Reality is that the world of engineering has long moved on to DSOs, which in on way or another have more than fully replaced DSO throughout the various industries, and this isn't changed just because some few hold-outs still cling to their old boat anchors. That is how it is.Considering that analog scopes are dead, it's silly to buy one for anything else than curiosity if you have a somewhat decent DSO already. As for the common example of the broke student/hobbyist, an analog scope can still be fine if it's free/very cheap (<$100 for better models), however, considering that older DSOs like the HP 54600 Series can often be found for a couple of hundred dollars, saving up a bit longer is in my opinion the better choice, rather than investing even an lower amount in a scope that has been obsolete 2 decades ago.

author: tggzzz
author_rank: Super Contributor
timestamp: June 24, 2016, 01:11:58 pm
content: I'll ignore your strawman arguments and where you stretch analogies beyond reasonable limits, and concentrate on...Quote from: Wuerstchenhund on June 24, 2016, 12:09:11 pm... and so eventually you, rather grudgingly, come to some balance and implicitly acknowledge the points other people have being making.I have used many top-of-the range HP digitising scopes (and other equipment) in the past, and have worked with the person that designed many of their digitisers, Tom Hornak (incidentally, his Czech name is usually misspelled: it should have an upside down circumflex on the n). Idohave a clue in this area.Being retired, I currently use a 350MHz Tek 485 and a 60MHz HP54621 - of the type you mention.I am familiar with both.IMNSHO, the HP54621 isuselessfor digital circuits - with modern jellybean logic its bandwidth is simply too low to assess signal integrity and timing violations. OTOH the 485 is OK, and even a 475 is adequate. Nor would I use any scope to debuglogicaloperation? No, a scope is th ewrong tool for that. Once I had assured signal integrity, I flip to debugging a logic signal using logic-based tools.For mosying around an unfamiliar circuit when debugging, the 485 is faster. In addition, the 54621 can be downright misleading in some circumstances, for example checking signal envelopes.OTOH, the HP54621 is better at catching turn-on transients - but even my Analog Discovery is adequate for that!Now, let me dispel some of your assumptions and implications...We are not offering opinions to professional engineers; they have better sources of information and ought to be able to assess their requirements without our help. We are offering opinions to beginners and amateurs, and we should act accordingly.Most analogue scopes you see around (e.g. 10/20MHz TV scope) aren't worth more than £20, if that. I've never said or implied otherwise. I've advised several people against buying such things. But I know several people that are reluctant to afford even £50 and are only interested in audio and mechatronics. For them such a scope may be the best way to contiune with electronics - especially when you consider that if they have to wait too long, they may well lose interest in the subject.However, a decent working analogue scope, e.g. Tek 465 or later, are available for £100, and they are worth having. And IMNSHO they are more useful than a low-end DSO.

author: rstofer
author_rank: Super Contributor
timestamp: June 24, 2016, 04:57:49 pm
content: Quote from: tggzzz on June 24, 2016, 01:11:58 pmAnd in the case of starving students, "saving up" isn't an alternative. If the scope is going to be of benefit, it needs to be timely. There will be opportunities down the road to upgrade.Yes, I know that colleges have labs - I went there once. It's just so much more convenient to experiment when time is available - usually the middle of the night, as I recall...

author: nctnico
author_rank: Super Contributor
timestamp: June 24, 2016, 05:18:37 pm
content: Quote from: tggzzz on June 24, 2016, 01:11:58 pmYou keep hammering on this but for the parts to achieve that performance they'll need very good decoupling and driving ideally terminated PCB traces. And even if those conditions are met you'll also need to have the right probes to measure the effects. But before all that you have to ask whether all of that is actually necessary and quite frankly: I don't think so. If you put a gate here en there as auxilary logic to drive a led or something like that there isn't going to be any trouble. Things are different if you have a large board with 100 or so logic chips but I don't think such boards are designed for commercial purposes nowadays.

author: tggzzz
author_rank: Super Contributor
timestamp: June 24, 2016, 05:40:03 pm
content: Quote from: rstofer on June 24, 2016, 04:57:49 pmPrecisely. I'm annoyed I forgot to mention timeliness.

author: tggzzz
author_rank: Super Contributor
timestamp: June 24, 2016, 05:49:46 pm
content: Quote from: nctnico on June 24, 2016, 05:18:37 pmI "keep hammering" on about it because I keep seeing people fail in this way - as I said, the last time was ~22hours ago!Of course appropriate probes are needed. What's new? You also need an appropriate scope.Of course decouplingoughtto be "good". What's new? But someone has to verify that the everythingis"good enough" - and not everybody gets it right, especially beginners.Of course 100 chip systems are few and far between. What's new? But nowadays many systems are made from multiple boards cobbled together, with all sorts of ensuing problems.I've even seen people say "there's no problem" (on a 60MHz scope), only to see a very visible problem (a static hazard) on a 350MHz scope. Bad design? Sure. So what; that's why we have scopes.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 24, 2016, 06:10:51 pm
content: Quote from: tggzzz on June 24, 2016, 05:49:46 pmIf you are referring to me, I agree with nctnico. As I said before, IME the sub nanosecond measurements you mentioned a few posts ago are not very relevant for hobbyist-level applications. To get an accurate measurement of the the slew rates you talked about you will definitely need something much more expensive than entry-level oscilloscopes and alligator clip probes - again, all this is applicable to hobbyist-level projects. Peace.

author: tggzzz
author_rank: Super Contributor
timestamp: June 24, 2016, 08:20:43 pm
content: Quote from: rsjsouza on June 24, 2016, 06:10:51 pmOnly if you were building a CNC machine in Hackspace yesterday!No,"seeing a person make the mistake" is "in the flesh", not "virtual", unfortunately.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 24, 2016, 09:23:42 pm
content: Quote from: tggzzz on June 24, 2016, 08:20:43 pmAh, ok. Our discussion happened at about the same timespan you mentioned and our experiences diverge...

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 25, 2016, 05:48:18 am
content: Quote from: rsjsouza on June 24, 2016, 06:10:51 pmhello friends,excuse, I am the hobbyist herea sheet metal worker, collecting all kind of scopes, mostly old and very old systems.In my opinion the testing of sub nanoseconds slew rates are requiering the knowlegde what I am doing there. This can be high upside from the knowledge of a hobbyist.I would select a 7104, plugged with 7A29 (this is a Tek oldie of 1GHz, I will store my shot with a camera) and a nice Fet probe to do that, but when I took the hook on a near to trustful rectangle generator (284) to see what my scope can do for me I see sometimes that is not a hundret per cent rectangle. There is some effects of reflectometry as a part of my signal. So I need at first the best possible setup to make shure that I will see what I will get.The knowledge of this effects is imho upside from hobbyists, you as EE can understand what is "true" on the display and what is "false". A fast DSO will show us the same, I am pretty shure in thatSo I think the most hobbyists will not get a good measurement of slew rates, also when they use a high rated DSO. So it`s very good that this tests are not very relevant for hobbyist-level applications.Today it is possible for a hobbyist to buy a 7104, or the 7844 Dual beam, at the time of this systems is was a dream, they was the high laboratory class and ultra expensive.greetingsMartin

author: tggzzz
author_rank: Super Contributor
timestamp: June 25, 2016, 06:22:20 am
content: A DSO and analogue scope with the same bandwidth should indeed show the same signal.You can find agoodold 350MHz analogue scope for EUR280 (Tek485). An equivalent DSO is significantly more expensive. That's an advantage to the analogue scope, but of course a DSO would have different advantages. Whether the advantages are benefits depends on individual's requirements and position. My objection is to people that ignore (and in some cases deny) the advantage and benefit, and presume everybody else is in the same position as they are. Imbalanced..I'll note that for many purposes, particularly with jellybean digital logic, a "low impedance Z0" probe is technically as good as a FET probe - and is more robust and probably cheaper. The major exception is with differential digital signals where a differential FET probe is necessary.

author: nctnico
author_rank: Super Contributor
timestamp: June 25, 2016, 07:53:57 am
content: Quote from: tggzzz on June 25, 2016, 06:22:20 amNo, you can buy a 500MHz DSO (which works fine but needs some cosmetic fixing) for less than that and the DSO will be much newer. Been there, done that.

author: GK
author_rank: Super Contributor
timestamp: June 25, 2016, 09:23:52 am
content: QuoteIf the DSO has a high enough sample rate. On my bench at work sits a Lecroy LT344, which was a kinda hot thing when it was bought brand new back in 2003 (I need to start pestering for an upgrade, but that is a different topic). Far from the pinnacle of DSO technology, but a good and well optioned performer in its price bracket. Its analogue bandwidth is 500MHz but I sure as hell wouldn't shift my equal-bandwidth 7904 off my home bench if I managed to pick up an LT344 or equivalent for a good price. The LT344 has a sampling rate of 500MSa. In real-time sampling mode that's a whopping 5 sampling points at 1nS/div. Suffice to say it's RTS waveform "fidelity" (for want of a better term) at the highest sweep rates hardly compares to that of my 7904. Yes there is ETS/RIS but they are workarounds with other drawbacks/limitations. It's takes a pretty high-end DSO to have a RTS performance that won't potentially leave one wanting over the high frequency waveform reproduction capabilities of a 7904, let alone a 1GHz-bandwidth 7104. You should see the stupid prices test equipment re-sellers down here still try to flog in-house-calibrated secondhand DSOs like the LT344 for.

author: tggzzz
author_rank: Super Contributor
timestamp: June 25, 2016, 09:31:07 am
content: Quote from: GK on June 25, 2016, 09:23:52 amI'm not going to argue withanyof that!But some will, I suspect.

author: System Error Message
author_rank: Frequent Contributor
timestamp: June 25, 2016, 11:32:30 am
content: so other than the occasional low priced 2nd hand bargains i supposed analog scopes arent much use other than a bargain for getting something of high frequency.Now that i have my DSO it is very decent and being able to freeze/store and than take measurements with the cursor including other tools it has i think makes it far better than an analog scope however i think the only issue with the DSO is sampling rate and aliasing which analog scopes dont do. Being able to connect to PC for further analysis is also a good thing because that 800x600 resolution doesnt compare to 1080p or 4K. Not sure if one would argue that CROs have the resolution of a photon. The features on a DSO are quite impressive.So im guessing when comparing an ASO do DSO of equal frequency the only use of an ASO is measuring signals where sampling is an issue?So other than the bandwidth what is the limiting factor of an ASO in picking up signals? Is it that it has to be processed to be shown on the screen making some sort of arbitary sampling rate or does the signal get converted into photons directly in order to give a theoretically infinite sampling?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 25, 2016, 11:36:25 am
content: Quote from: GK on June 25, 2016, 09:23:52 amNo, the WaveRunner LT344 wasn'ta hot thingin 2003. Not evenkinda ofThe WaveRunner LT344 came out in 1998, and in 2003 it had already been succeeded by two generations (WR2LT, WR6000). Most of the original WaveRunner LT scopes were bought for non-EE tasks like physics or mechanical engineering where the low sample rate wasn't an issue, and IIRC production of that series stopped at the end of 2001 or early 2002 as it didn't sell becasue the successor (WR2LT) offered much better specs (sample rates from 1GSa/s to 4GSa/s) and more performance for the same price. The WR2LT came out in 2001 btw.In 2003, the LT344's successor WR2LT was already in its last production cycle as the WR2LT's successor WaveRunner 6000 came out the same year. And the WR6000 (a Windows2000 based X-Stream scope with sample rates of 2.5Gsa to 5GSa/s) was a huge step up from the older WR2LT.If you really bought a LT344 in 2003 then you simply bough an obsolete out-of-production scope.QuoteNo, not really. Not even back in 2003. I agree that the LT344 pales in comparison to the Tek 7900 in terms of real time performance, but as I said the LT344 is pretty old technology (1998 vintage), and even back in 1998 it wasn't exactly the epithome of digital scopes, not even from LeCroy (the WRLT was pretty much LeCroy's new mid-range series back then, they also had their LT Series of high-end scopes with up to 1GHz BW and 8GSa/s sample rate). However, a WR2LT already offered much better RTS performance than the old WRLT, and in 2003 the actuala hot thingwould have been a WaveRunner 6000 (and the 7904 wouldn't look exactly great against a 1GHz WR6100).And then there's the thing that 1GHz is pretty much the upper BW limit for analog scopes, while even back in 2003 you could get fast real-time scopes with 6GHz and sample rates of 20GSa/s.And it didn't take that long until DSOs even exceeded the waveform rates of analog scopes.QuoteYes, but that's pretty much true for all obsolete pieces of test gear. Just have a look on ebay at the sometimes mind-blowing asking prices for gear that these days can easily replaced by newer and cheaper gear. But used T&M brokers live in their own bubble, one where competition and technical progress (which regularly brings us better performance at lower prices) doesn't exist and where old crap gains in value like good wine. They also don't seem to mind that they're sitting on their stock that is pretty much depeciating its already low value every day it just sits there. The rules of economics have already sorted out many of them, and in the days of ebay many have realized that these days it's better to sell stuff fast and cheap with little profit margins than hang onto it for years to wait for that one buyer who really needs a certain piece of kit and who's willing to pay hyperinflated prices.

author: GK
author_rank: Super Contributor
timestamp: June 25, 2016, 12:13:18 pm
content: Quote from: Wuerstchenhund on June 25, 2016, 11:36:25 amI wrote "a kinda hot thing". And you appear to have missed my following sentence:"Far from the pinnacle of DSO technology, but a good and well optioned performer in its price bracket".Quote from: Wuerstchenhund on June 25, 2016, 11:36:25 amAny DSO with a 1GHz analogue bandwidth and an 8GSa/s sample rate is pretty damn "high-end" from a general hobbyist/home lab owners perspective (which was the context of the discussion), be it a 13 year old design or a current production model.But this is taking the discussion off track. I simply used the LT344 vs the 7904 to raise atechnicalcontention with tggzzz's assertion that "A DSO and analogue scope with the same bandwidth should indeed show the same signal" as these are "same bandwidth" scopes that I handily have first hand experience with. It's nice that you "agree that the LT344 pales in comparison to the Tek 7900 in terms of real time performance" but I don't know why the contribution in addition to that is necessary.And yes we really did buy a LT344 "brand new" in 2003. If it was already out of production for a year or two as you claim then it would have been stock that the distributor was keen to shift, which is likely why I recall the favorable price vs performance standpoint. "Obsolete" or not it satisfied our requirements.Quote from: Wuerstchenhund on June 25, 2016, 11:36:25 amAnd your point is? I haven't seen any sellers down here trying to flog 7904's for $5000 plus. I am also not aware of any affordable (compared to what I payed for my 7904 and the wrecks to serve as a life-time supply of spare unobtanium) current production 1GHzBW/8MSa/s entry-level DSOs.

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 25, 2016, 12:55:43 pm
content: a 7904 (empty frame without plugins) is good for 100$ / €.If you need spare parts it is a good idea to ask in the Tek collectors communitys if they have, like the "TekScopes" at yahoo or my wellenkino.deWe collect not only scopes, also the little spare bags and boxes from oregon.greetingsMartin

author: joeqsmith
author_rank: Super Contributor
timestamp: June 25, 2016, 01:11:49 pm
content: The roll off may not be at all the same. Long gone are the days of 0.35....Quick Google search "rise time bandwidth modern DSO filters", first hit:http://www.edn.com/design/test-and-measurement/4340453/Relating-wideband-DSO-rise-time-to-bandwidth-Lose-the-0-35-Quote from: tggzzz on June 25, 2016, 09:31:07 am

author: joeqsmith
author_rank: Super Contributor
timestamp: June 25, 2016, 01:25:05 pm
content: Quote from: Wuerstchenhund on June 24, 2016, 12:09:11 pmThere is no sign of intelligence here... All of my test gear is from yesteryear. My newest scope is 10 years old.But wait. Don't you own a 7300 and 64xi? I think you need to send those old relics to me or people are going to start thinking you too are less intelligent!

author: GK
author_rank: Super Contributor
timestamp: June 25, 2016, 01:37:11 pm
content: Well a high enough sample rate is just one requirement; probably (actually not really probably) a great deal more potentially significant than whether or not the rise-time/bandwidth relationship between two scopes with the same specified -3dB bandwidth differs by 0.35/RT to 0.4 or 0.5/RTQuote from: joeqsmith on June 25, 2016, 01:11:49 pm

author: tggzzz
author_rank: Super Contributor
timestamp: June 25, 2016, 03:01:43 pm
content: Quote from: nctnico on June 25, 2016, 07:53:57 amWhich ones, out of curiosity?

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 25, 2016, 03:02:07 pm
content: Quote from: GK on June 25, 2016, 12:13:18 pmBut that's the point, in terms of real-time performance it simply wasn't. Not in 1998, and a lot less in 2003.QuoteI gess the various owners of LeCroy LC Series scopes in this group would beg to differ, and these scopes often go for way below the $1k mark (nothing for the broke student, but well into hobbyist territory, which also are pretty much the only people that buy these old scopes today).QuoteBut they aren't the same BW scopes. The LT344 doesn't have 500MHz real-time bandwidth, that's merely the analog bandwidth of the front end. A DSO's usable BW however is determined by not just the FE but also the acquisition system BW, and for the LT344 in real-time mode the latter is <250MHz.QuoteThat is well and fine, but again, I was just addressing your"Far from the pinnacle of DSO technology, but a good and well optioned performer in its price bracket"statement. In terms of real-time performance for a 500MHz DSO, the LT344 was sub-par already the day it came out. Which makes a comparison as real-time scope against a 500MHz+ analog scope rather pointless.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 25, 2016, 03:26:02 pm
content: Here is another fairly decent article on filtering if interested.http://cp.literature.agilent.com/litweb/pdf/5988-8008EN.pdfQuote from: GK on June 25, 2016, 01:37:11 pm

author: GK
author_rank: Super Contributor
timestamp: June 25, 2016, 03:51:45 pm
content: Quote from: Wuerstchenhund on June 25, 2016, 03:02:07 pmThe real-time performance is only one performance parameter. For the going price in 2003, compared to a host of alternative and immediately available offerings for the same $ on loan for evaluation from the distributors that we compared it to, it was exactly what I wrote.QuoteI qualified my statement with the word general; obviously in vain. If the hobbyist in general had ample opportunity to go out and simply buy a practical 1GHz/8MSa/s DSO for "way below the $1k mark" then the RIGOL threads around here would not run into 100 pages. Everyone would say "go buy a Lecroy XXXXX", not "go buy a RIGOL DS1054Z"!QuoteYes they are the same bandwidth scopes - the 500MHz analog bandwidth combined with RIS makes the LT344 a 500MHz scope (with limitations). And FFS I know that the LT344 doesn't have a RTS bandwidth of 500MHz and is Nyquist limited to <=half that. That was the whole freaking pointQuoteThe utterly elementary, uncontroversial technical point that I made w.r.t. bandwidth (analogue) and sampling rate and high frequency waveform reproduction has absolutely no contingency whatsoever to the technical caliber (one way or the other) of the LT344 (or any other DSO for that matter) 13 years ago, today, yesterday or at any other point of time in history.

author: Someone
author_rank: Super Contributor
timestamp: June 25, 2016, 11:36:46 pm
content: Quote from: GK on June 25, 2016, 03:51:45 pmMr W seems to be in a special world where Lecroy products are available at huge discounts to the open market, not that they'd share with us how to get these amazing bargains. When us regular people compare eBay or other auction prices the traditional rule of "you get what you pay for" still applies.

author: G0HZU
author_rank: Super Contributor
timestamp: June 26, 2016, 12:56:39 am
content: It seems like every scope thread like this gets trashed by the sausage dog one way or another...FWIW I still have a Tek 465 on my workbench and it one of only a few select items that never leaves my workbench. My background is RF and I've got some decent (and fairly modern) RF test gear here. But the 40 year old Tek 465 is still very useful when doing quick/casual sanity checks on a modulated RF waveform or a LF waveform that may have issues with RF instability in parts of the waveform.QuoteThat probably places me into the moron category because I still have (and use) a 50 year old HP8405A 1GHz vector voltmeter and a 50 year old HP431C/HP478A 10MHz-10GHz RF power meter.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 26, 2016, 03:34:33 am
content: Inappropriate post removed. We don't do provocking eath other on this forum, I don't have time to sort the shit storms out it causesSimon

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 26, 2016, 05:17:54 am
content: Consider this image of Jim Williams, five years later for a moment:http://www.edn.com/design/analog/4442194/Remembering-Jim-Williams--5-years-later"Despite Linear Tech making high-performance analog chips, Williams used classic test equipment, like vintage Tektronix oscilloscopes and old HP equipment. That may have been inspired from his work at MIT as a young man, keeping the lab equipment working and designing custom circuits. Paul Grohe, a friend and fellow application engineer at Texas Instruments notes, “Jim’s love of old hardware may be due in part to the fact that you can still fix those old scopes. The new stuff is full of hybrids and proprietary chips that can only be repaired at a factory service center.”It appears the current generation of electronic folks who are digital/software/code centric simply do not have an appreciation of this analog stuff, appreciation of how rational state of the art test gear designs from the golden era really is and the fact many of these classics are timeless.Being the owner-user of an hp 8505A vector voltmeter and numerous other vintage test gear that required understanding and ability from the user, not just knowing how to access each and every feature on the display or writing code to drive each and every measurement.Study the working of the hp 4815A vector impedance meter circa 1967.. and be surprised is inside and requirements for accuracy. What can be learned from this classic impedance measurement instrument?http://people.wallawalla.edu/~rob.frohne/Radio%20Schematics/HP%204815A%20Manual.pdfBernice

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 26, 2016, 07:01:41 am
content: hello Bernice,I think the friends here will only roll their eyes when we begin to talk about vintage scopesIt will be a good idea to move that to my tread of restoration pictures here in the forum.We are not modern.greetingsMartinthis picture is for remembering to something from yesterday.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 26, 2016, 08:01:46 am
content: After staying away for 6 months, little if anything has changed. It appears each and every time the topic of Analog Real Time CRT based O'scopes -vs- DSO, the same tiresome items appear, same individuals, same attitudes resulting in much of nothing except the war of words, egos and similar. Life is too short for individuals who are learning resistant and entrenched an blinded by their individual myopia.Facts are folks, both have their place depending on the specific needs. Using the correct tool for the requirement IS what should be done, not falling into the fantasy one is always better than the other.Bernice

author: Fungus
author_rank: Super Contributor
timestamp: June 26, 2016, 10:15:54 am
content: Quote from: Rupunzell on June 26, 2016, 05:17:54 amSure, he would have has a collection of thebestvintage equipment, a large collection of probes to go with it, a shed full of spare parts to keep them running, the knowledge to pick the right probe for a job, the knowledge to set the controls properly, the knowledge to interpret the results shown on the screen, etc.The average electronics newbie? Not so much.Telling newbies they should be scouring eBay for used Teks? Very bad advice.

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2016, 10:24:36 am
content: Quote from: Rupunzell on June 26, 2016, 08:01:46 amHint: nobody drives in a model T Ford for their daily commute. Advising young engineers to stick with old and clunky equipment isn't helping them.I grew up with analog scopes too but using one nowadays? I really see no reason to do so because a DSO can do everything an analog scope can and does it much better.

author: Jwalling
author_rank: Unknown
timestamp: June 26, 2016, 10:47:15 am
content: Quote from: nctnico on June 26, 2016, 10:24:36 amI'd say "I really see no reason to do so because a DSO can do everything an analog scope canand moreand does it much better."Jay

author: G0HZU
author_rank: Super Contributor
timestamp: June 26, 2016, 11:39:16 am
content: But isn't this a thread about 'looking' at the display so see fluid changes in a waveform? The OP wasn't interested in storage of the waveform.So this is a human factor question. A traditional analogue scope is a wonderful tool for 'observing' erratically modulated RF waveforms, eg human speech fed into an AM or SSB transmitter for example.You can get a wonderfully fluid display from pretty much any analogue scope from the last 50-60 years assuming it has enough bandwidth.I really don't think I would reach for a DSO here if there was an analogue scope next to it. The old CRO will do a very good job here.If you actually wanted to capture the modulation and post process it rather than just look at it then the analogue scope can't help at all and the DSO would be the tool of choice.

author: coppice
author_rank: Super Contributor
timestamp: June 26, 2016, 12:48:23 pm
content: Quote from: Rupunzell on June 26, 2016, 08:01:46 amIf these older machines are so indispensable for certain applications, I wonder why nobody makes them any more? You would think there would be a market for them.

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2016, 01:06:37 pm
content: Quote from: G0HZU on June 26, 2016, 11:39:16 amThe thing is that just looking at something usually doesn't result in quantifyable measurements. It can look OK but it is really? With a modern DSO you can use the FFT function to look at modulated signals and quantify whether it is within limits or not.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 26, 2016, 01:20:54 pm
content: Quote from: Someone on June 25, 2016, 11:36:46 pmOnly in your mind. In reality, there are lots of good 2nd hand deals out there for those that aren't lazy:500MHz 4Ch for less than $600:http://www.ebay.com/itm/LeCroy-Waverunner-LT354M-Oscilloscope-500MHz-1-GS-s-DSO-/231903891732http://www.ebay.com/itm/LeCroy-Waverunner-LT354M-Oscilloscope-500MHz-1-GS-s-DSO-/231910736019(BTW: these have 4M sample memory, not 250k as stated in the text!)There was also one with a few scratches on the protective transparent plastics screen (which isn't difficult to replace) for $460, so pretty much DS1054z money. There's no serial decode but as compensation you get 500MHz BW, 1GSa/s on all channels, and (depending on which software options are enabled, which isn't clear from the text) advanced FFT with up to 1Mpts, jitter/timing analysis, history, statistics and a ton of other math and analysis functions.1GHz and 8GSa/s for a bit over $1k:http://www.ebay.com/itm/Lecroy-LC584AL-1GHz-and-8GS-s-in-perfect-working-condition-/272224857602(BTW, all the software options for that scope canlegallybe enabled for a few bucks/free, as LeCroy has made them available to hobbyists years ago!)2GHz, 16GSa/s and 32M sample memory for $1600:http://www.ebay.com/itm/LeCroy-WavePro-960-Series-2-GHz-4-Channel-Color-LCD-Display-Digital-Oscilloscope-/2523920282954Ch 500MHz 5GSa/s 24Mpts plus lots of very advanced waveform analysis functions and serial decode for a wide range of standards for less than $1500:http://www.ebay.com/itm/LECROY-WAVERUNNER-6050A-500MHz-QUAD-5GS-s-DIGITAL-OSCILLOSCOPE-/231965700171www.ebay.com/itm/LECROY-WAVERUNNER-6050A-500MHz-QUAD-5GS-s-DIGITAL-STORAGE-OSCILLOSCOPE-/231977345364All within the price range of your average hobbyist gear, with best regards from my "special planet"However, in case you were talking about new gear, I guess you missed that I explained, many times btw, that the best way to get bargain prices for kit from any big brand is to go through the manufacturer, talk to their sales staff and start negotiating. Base price for scope plus a range of options thrown in is pretty easy to achieve. There often are also demo scopes which often go for a lot less than 70% of the original price, plus they usually are loaded with options.If you go through resellers (which want their slice of the cake) then worst case you'll pay list price and best case you get a few bread crumps.This of course doesn't work everywhere, i.e. countries where the manufacturer has no office, in which case you'd have to go through the importer. If you happen to live at such a place, bad luck.So no, it's neither "my special world" nor a secret.QuoteThat rule pretty much always applies, but if you can't find any bargains then maybe, just maybe you're simply not looking hard enough? There's no such thing as free lunch, and if you want to find good deals, no matter what brand you're looking into, you have to do your homework.If you can't be arsed to do that then you'll pay premium. It's as simple as that.However, all this is unrelated to the topic of this thread. If you truly want to talk about how to find bargains then I'd suggest you start a new thread.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 26, 2016, 01:22:00 pm
content: Pretty much every post I make is intended to provoke members.Quote from: joeqsmith on June 26, 2016, 03:34:33 am

author: chris_leyson
author_rank: Super Contributor
timestamp: June 26, 2016, 01:26:43 pm
content: QuoteI would second that.I have two TEK 7854s, I have to re-cap the second one, but for 35 year old kit they're OK they do what I require from a scope but they need constant adjustment or repair. For higher frequency work I have the option of a 7L12 spec-an plugin or I use HP54610 (750 MHz BW) depending if I'm working in the frequency or time domain. Both scopes under sample so they are good for repetative signals but no good at all for capturing single shot transient events. As for FFTs on sampling scopes, OK for a quick look but I can get an extra 30dB dynamic range from a traditional swept analyzer. It all depends on what you want to measure.

author: G0HZU
author_rank: Super Contributor
timestamp: June 26, 2016, 01:46:14 pm
content: Quote from: nctnico on June 26, 2016, 01:06:37 pmYou might also want to look in the time domain at the RF envelope to see how an ALC/AMC circuit is performing when fed with human speech. Sure, it's just a quick/casual 'visual' measurement in real time but the CRO is very good at this.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 26, 2016, 02:15:55 pm
content: Quote from: G0HZU on June 26, 2016, 12:56:39 amYeah, I get that for some (mental) oldtimers in here facing reality might hurt. I also get that personal attacks are clearly an easier way to deal with it than facts and arguments (not that this is surprising, after all the world currently has to deal with the fall-out caused by a bunch of people that were completely oblivious to facts and arguments).But still, reality is on my side as clearly no-one really makes analog scopes any more, which wouldn't be the case if they were really so useful as the analog scope proponents claim them to be. Maybe manufacturers are all idiots, but I'd guess more likely they know that in the real world they just wouldn't sell.QuoteGreat for you. So you really wanna suggest that this is a sign of intelligence?Just to make it clear: there's nothing wrong with using old or even antique test gear if it suits you. But there's a lot wrong in talking beginners into sinking money into archaic pieces of test equipment no-one makes any more despite it's aleged aleged superiority, which is what happens pretty much every time the question re. analog scopes comes up. It's poor advice by any standards, and while it might massage your ego that another 'young one' could be saved to follow the old paths, it only serves to hurt beginners.

author: G0HZU
author_rank: Super Contributor
timestamp: June 26, 2016, 02:50:54 pm
content: QuoteThe thread wasn't about who still makes analogue scopes. It's about how fluid the display is when looking at fast changing waveforms.Can you suggest an affordable DSO that will provide me with a display as visually fluid as my Tek 465? The Tek 465 cost me about £50 back in the 1990s.QuoteMaybe you need to email the people of low intelligence at Keysight and the various NIST calibration houses that still use the HP478A power sensor (designed in the 1960s) as a transfer standard to calibrate modern RF power meters.AFAIK some NIST calibration houses use the HP8405A vector voltmeter (designed in 1965?) to cross check various atomic frequency standards over time. They may use something newer today but up until recently the old VVM was a classic tool for stuff like this. I bought it to measure/verify negative impedances for some study work but maybe you also need to email the people who use 1960s VVM technology (to cross check atomic standards) to tell them how dumb they are.

author: tggzzz
author_rank: Super Contributor
timestamp: June 26, 2016, 04:23:08 pm
content: Quote from: Rupunzell on June 26, 2016, 08:01:46 amYup. Dogma is simplistic and annoying.The only change I would make is to say "using thebest availabletool for the requirement". A working scope in the hand is worth two on ebay

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2016, 04:38:32 pm
content: Quote from: G0HZU on June 26, 2016, 01:46:14 pmIf I may interpret 'seeing fluid changes' as slow phosphor response then I have to say a DSO can do the same by adjusting the persistence time.

author: Fungus
author_rank: Super Contributor
timestamp: June 26, 2016, 05:05:41 pm
content: Quote from: Wuerstchenhund on June 26, 2016, 01:20:54 pm+$300 shipping...Quote from: Wuerstchenhund on June 26, 2016, 01:20:54 pm+$683.63 shipping...(And let's hope customs don't spot it or it'll be 25% more on price+shipping)

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2016, 06:03:46 pm
content: The shipping costs can be reduced if the seller is willing to use USPS. Otherwise a forwarding service can be cheaper.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 26, 2016, 06:05:25 pm
content: Quote from: Fungus on June 26, 2016, 05:05:41 pmThese might be the shipping costs to your place (wherever that might be, since you didn't state location), not to everywhere. As to customs, here in the UK I pay 'just' 20%, not 25%, which is because VAT rates vary by country.If you buy from abroad then shipping and customs need considering. If you buy products made abroad then you pay at least some of the cost to get the item into your country through the inflated sales price. That's just how it is with international trading.Besides, it shouldn't be surprising that US buyers get some of the best prices, because this is pretty much true for the majority of technical goods and has been this way for a long time. If you don't live in the US then in generally you'll pay more, that's simply how it is.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 26, 2016, 06:36:51 pm
content: Quote from: G0HZU on June 26, 2016, 02:50:54 pmNo, the thread was about if there are any advantages in buying an analog scope in addition to a decent DSO, and some of the analog proponents claimed that an analog scope still maintains various advantages over a modern digital scope.The point is that if that were true, then this would raise the question why no-one makes analog scopes any more. Something which of course so far none of the analog scope proponents has answered.QuoteIf staring at waveforms is your thing then one nice example would be the HP 54645A, which was HP's first DSO with MegaZoom ASIC and pretty much the first DSO with high waveform rates and does intensity grading. It has the same BW (100MHz) as the Tek 465, and replicates the 'analog' feel very well IMHO (much better than many other DSOs).Ebay UK tells me that these days Tek 465s sell for somewhere in the region of £80 to £190. It only found one HP 54645 on ebay UK, which went for £216, but that was the 'D' version (the MSO version), and it came with the logic cable+pod (which alone go for quite a bit of money).I'd expect a 54645A to fetch something around £120 to £150 in the UK in good, fully working condition. With some patience, you could probably even get one of the later Agilent 54600 scopes, which offer a few advantages over their HP predecessors, for similar money.QuoteTalking about dumb people, you know that reading comprehension is generally considered a sign of intelligence?So let me just repeat what I said in my last post (the part you didn't quote):QuoteThe relevant part is highlighted, and the part you should have paid more attention to is underlined.So your blathering about what old kit calibration houses use is completely irrelevant, because they're not the ones who try to talk beginners to sink money in antique test gear.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 26, 2016, 07:19:09 pm
content: Most amazing discover in this pile of text...Laws of Physics and how this electronics stuff has changed to accept and discover the newest and latest IS the greatest.Imagine that...Bernice

author: G0HZU
author_rank: Super Contributor
timestamp: June 26, 2016, 07:31:34 pm
content: QuoteNo it wasn't. It gave me an opportunity to demonstrate your ignorance about 50 year old test gear and how even the top RF companies still use tech this old.QuoteCome on, admit it... you had a rush of blood and went into 'put down' mode and then typed out the drivel above.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 26, 2016, 07:32:46 pm
content: This was the intro from years ago, Aerospace engineer, Really-Honest ?https://www.eevblog.com/forum/chat/new-member-please-introduce-yourself/msg182870/#msg182870BerniceQuote from: Wuerstchenhund on June 26, 2016, 06:36:51 pm

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 26, 2016, 07:34:25 pm
content: Appears that way, have a look at history of post.BerniceQuote from: G0HZU on June 26, 2016, 07:31:34 pm

author: tautech
author_rank: Super Contributor
timestamp: June 26, 2016, 08:36:52 pm
content: Quote from: coppice on June 26, 2016, 12:48:23 pmThey do. Many obscure Asian manufacturers still have new CRO's on their websites but I've not seen any over 100 Mhz BW and I'd still choose a DSO over a new low BW CRO.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 26, 2016, 08:47:44 pm
content: From my point of view there are a few common denominators across these discussions of oscilloscopes:- a used analog oscilloscope is nowadays not recommended for a beginner to invest a somewhat large sum of money (=their "oscilloscope money") given the risk of getting a worn out (=close to failure) or faulty equipment. Conversely, if the price is low and/or the availability is restricted =(nothing else can be had), then the principle of "something is better than nothing" prevails- a used analog oscilloscope may be a great second equipment for hobbyists above a minimum level of experience, given the opportunity they bring tolearn aboutimprove the process of interpreting waveforms andimprovingthe skills to get a "feel" for what is shown on the screen.- a used digital oscilloscope is trickier for a beginner to get it right, given there are additional specifications (other than bandwidth/channels) that play an important role in the usability of the instrument. These specifications (SPS, resolution, acquisition memory, waveforms/s, etc.) are added to other less obvious but still important usability treats, such as interface responsiveness, startup times, etc. All are related to the built-in processing speed of the equipment - after all, they became actual computers in an oscilloscope's skin.- despite that, a digital oscilloscope for a beginner is closer to what they will face in the marketplace, therefore it may leap they learning curve.- a new digital oscilloscope can be bought today with some decent specifications at a reasonable price. That reduces the risk beginners investing a larger sum of money.- no matter how you look at it, digital oscilloscopes are almost hopeless to be repaired (certain analog scopes are easier, but you frequently need part donors) - that is mostly applicable to dedicated and programmed ICsWell, hopefully the overall idea is here, but additions are welcome.

author: Fungus
author_rank: Super Contributor
timestamp: June 26, 2016, 08:59:12 pm
content: Quote from: tautech on June 26, 2016, 08:36:52 pmFarnell lists 12 of them.GW Instek will sell you a 20MHz analog scope for $530:http://www.newark.com/gw-instek/gos-620fg/oscilloscope-bench-2ch-20mhz/dp/64M4798

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2016, 09:23:28 pm
content: Quote from: rsjsouza on June 26, 2016, 08:47:44 pmIMHO this a myth. Any higher end oscilloscope analog or digital will contain proprietary parts. I have run into this problem when trying to repair both analog and digital scopes.

author: tggzzz
author_rank: Super Contributor
timestamp: June 26, 2016, 09:29:53 pm
content: That is pretty sane and sensible, with the caveat below.Quote from: rsjsouza on June 26, 2016, 08:47:44 pmI don't understand what you mean there, unless you are thinking of just voltage / time / frequency measurements. Interpreting an oscillogram to understand what's happening in a circuit doesn't change too much between analogue and digital.Quote

author: Jwalling
author_rank: Unknown
timestamp: June 26, 2016, 09:43:12 pm
content: Quote from: Fungus on June 26, 2016, 08:59:12 pmJay

author: tautech
author_rank: Super Contributor
timestamp: June 26, 2016, 09:53:29 pm
content: Quote from: nctnico on June 26, 2016, 09:23:28 pmIn your opinion maybe, but all must acknowledge that for DSO's of today, schematics are generally not available whereas most scopes (CRO's and DSO's) of yesteryear they are.For the novice with very limited understanding of the basic building blocks involved schematics are very important if one has to have any hope of repairing a scope.The beginner really only has PCB swap options to repair a busted scope and those with modular construction are then a big plus.For those with repair experience and the "tools" this in not such an issue if parts can still be sourced, most but not all can.Therefore best advice for those without scope experience that can't/won't buy a modern DSO is to ensure schematics are available and there is a minimum (preferably 0)of unobtainium parts required if/when they might be needed.

author: nctnico
author_rank: Super Contributor
timestamp: June 26, 2016, 11:39:28 pm
content: Quote from: tautech on June 26, 2016, 09:53:29 pmIMHO a novice shouldn't get a (likely) broken scope (or any gear) other than for the purpose of fixing it while using a scope which works and is reliable. Sure I like to have schematic of my gear but the reality is that in many cases proprietary parts for older equipment can not be bought so schematics aren't helping much. Also service manuals for newer equipment usually contains a detailed block diagram which is just as usefull as a schematic. Sure a block diagram doesn't have the part values but on the other hand it clarifies how the signal flows through a piece of equipment more clearly than a schematic does.

author: David Hess
author_rank: Super Contributor
timestamp: June 27, 2016, 01:23:21 am
content: Quote from: tautech on June 26, 2016, 09:53:29 pmService manuals with schematics vanished sometimes in the early 1990s. I have heard various justifications for this but the best was that detailed design documentation was fueling an increase in patent lawsuits.QuoteI would not go quite that far. Only a minority of problems involve custom parts and even with them, it will almost always be significantly less expensive to buy a parts mule if necessary than a new instrument with equivalent capability.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 27, 2016, 02:24:24 am
content: I was hoping to get a PM showing where I had crossed the line as I really don't know. I was a thinking he was in sales, never would have guessed Aerospace engineer. I did a quick google search and found this:horsemeatburger 3/29/13That's actually written by me ;-) I'm glad you liked it.. . .Hello folks,I just saw a nice review of a LT224 scope on the EEVBLOGforum site here:https://www.eevblog.com/forum/testgear/lecroy-waverunner-lt-224-review-and-%28partial%29-teardown/I suspected it was the same person by their tone. This was basically part of what I had posted. Let's see if it gets pulled.Quote from: Rupunzell on June 26, 2016, 07:32:46 pm

author: joeqsmith
author_rank: Super Contributor
timestamp: June 27, 2016, 02:28:39 am
content: Wuerstchenhund, I was curious why you never post about anything you have actually done. This is partly why I was guessing you were in sales. I had watched your video and had not realized you sold the 64xi. So you never tried the SSD or repairing it?This was basically part of my post. Was this the problem?

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 02:29:59 am
content: Quote from: Someone on June 25, 2016, 11:36:46 pmGeography is important. I spent some time scourging the domestic second hand market down here to no avail before deciding to buy a new Rigol 1202CA (200MHz/2GSa/a) a few years ago. That cost me a little over a grand AUD and was a much better $/performance deal than anything I could find used, even without factoring in that the Rigol was new and warranted.My 500MHz BW 7904 goes down to 1nS/div. There is currently a (local to me) Lecroy 7200A 500MHz/1GSs/s DSO boat anchor listed on ebay for a rich $900. This is typical. I wouldn't consider this dinosaur to be a significant advance over my Rigol and even so the sampling rate satisfies Nyquist for the 500MHz bandwidth it is still far from the equivalent real time performance of my 7904; 1 sample per division at 1ns/div sweep time just wouldn't cut it.To match the 7904, 500MHz/5GSa/s would be the minimum required spec. The "entry level" new DSO bracket has not technically progressed this much since I bought my 200MHz/2GSa/s 1202CA and the options for sensibly priced second hand DSOs in this performance bracket on the local market are generally non existent.The only worse thing is trying to find a decent used spectrum analyser.Buying from the US from a private seller is an uncomfortable gamble for anything upwards of $1k for a whole host of reasons. You can of course buy used but "guaranteed and operationally checked" from a test equipment reseller with the assurance that you're not going to be sent a dud or something packaged for international shipping in butchers paper, but you will typically pay through the nose for the privilege. That is often enough to make the used option economically unviable even before factoring in often stupid "handling" and shipping charges.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 27, 2016, 02:35:49 am
content: The last comment I had made was about still running the SSDs in the two old DSOs along with the 1G Ethernet for well over a year now contrary to Wuerstchenhund's advice of the potential problems. Getting the data off that old 8K at a decent speed has been great.Maybe this is what did it?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 27, 2016, 02:43:52 am
content: Quote from: GK on June 27, 2016, 02:29:59 amBuying in the US can be a bit of a gamble. I always assume the seller is not capable of fully testing the device and it will be bad. I've bid on some fairly high priced equipment but have always made sure there was something written down about a trial period and such. Normally, the higher end stuff was not a problem.I think pretty much every peace of TE I purchased used off eBay had a problem. Relays, caps, mechanical connections and switches were by far the most common problems.

author: tautech
author_rank: Super Contributor
timestamp: June 27, 2016, 02:46:26 am
content: Quote from: joeqsmith on June 27, 2016, 02:24:24 amOffensive or personal comments that a moderator agrees are such will get a response and get deleted.It all stems from a "Report to Moderator" action unless a moderator is closely watching the thread.Unles the moderator "deems" it's serious you won't get notified.Some discussion of moderators actions get discussed here:https://www.eevblog.com/forum/chat/moderation-reports/

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 27, 2016, 03:13:07 am
content: For those who are entrenched in the belief and idea that there is zero value to repairing great classic test gear, try designing a O'scope from scratch. This would include designing the CRT, mechanicals along with each and every aspect of the instrument. Much will be learned in this process. What is not often appreciated by the current generation of "electronics" folks is just how much can be learned from what has been done in the past to push the absolute limits of device technology and laws of physics.Try this and be humbled by how cleaver great designers from the golden era of test gear really were. Much of what is done today even in the absolute state of the art instrumentation is really an extension of what was done and established in the past. Gaining a deep and complete understanding of these fundamental designs have extremely great value to anyone wanting to learn electronics.Many if not most of the very best circuit designers I have met, known, conversed with and shared with have all studied stuff like this and all have learned a great deal from them. Much of this knowledge and expertise is NOT found in any text book or academia based education.This is why one of the very best things any novice or anyone interested in electronics should learn from history.BerniceQuote from: nctnico on June 26, 2016, 11:39:28 pm

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 27, 2016, 03:21:01 am
content: Wuerstchenhund intro'ed as Aerospace Engineer doing Radar and etc...EE bud has not been having good results with new LeCroy stuff, They fail a lot and too many software bugs complete with quirks.BerniceQuote from: joeqsmith on June 27, 2016, 02:28:39 am

author: joeqsmith
author_rank: Super Contributor
timestamp: June 27, 2016, 03:34:59 am
content: I guess everything I write could be offensive to the right person. Not sure why Wuerstchenhund would have a problem with me pointing out other public materials they have posted or for stating the changes I had made to my DSOs were still working fine.Or why anyone else would have reported the post.Then again, I have seen a few members accounts get banned and after reading the threads could not figure out why. Kiriakos-GR was similar to Wuerstchenhund. Both provided some good info. Both had strong opinions. One gets kicked.Really strange.Quote

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 27, 2016, 05:39:48 am
content: Quote from: joeqsmith on June 27, 2016, 02:35:49 amAll I can say is that I don't know why your posts have been removed, and pointing out that you haven't seen any of the problems I said could happen when plugging in the network card and older revisions of a certain Transcend SSD certainly isn't something I'd report (nor is it anything that should be removed!).I've reported posts a few times in the past, but most all of them were just for off-topic threads with a request to move it to the appropriate forum, and two instances because a certain member was specifically trying to provoke dissent.I certainly would never report a posting just disagreeing with me.QuoteNo, I'm not in sales, although I happen to spend a big part of my professional time buying loads of test gear, in addition to more managerial stuff these days. As to what I do, one of my and my employers' rules are that important work stuff stays at work, and that includes details about the projects I work on, or where they are located.I'd gladly talk about more mundane and general stuff (i.e. buying test gear in general, or not work related technical things), though.As to the WR64Xi, as stated the last time we discussed the SSD topic I did put one of the newer Transcends with the 44pin UDMA fix in the scope, and like yours it ran fine (but then, as stated back then this was a problem with older versions of that SSD and the 44pin cabling of the WRXi which doesn't support higher UDMA modes). I also had the acquisition board connectors fixed, I shot the shoddy video when the scope was back in fully working condition.Unfortunately a former colleague saw the scope when visiting, and talked me into selling it to him. That bastard!QuotePretty much all my personal test gear was bought from the US via ebay, simply because prices and availability were so much better than here in the UK or in mainland Europe. The only things I bought in the UK were my Agilent E3632A PSU and my Agilent E4406A VSA. Never had a problem, but I check feedback and what else the seller has sold. But buyer protection on ebay works very well in general, if an item fails then you've 45 days to complain, and if the seller doesn't return your money then ebay will do so forcibly.QuoteHey, no reason to get offensive!

author: Someone
author_rank: Super Contributor
timestamp: June 27, 2016, 10:08:21 am
content: Quote from: GK on June 27, 2016, 02:29:59 amInternational shipping isn't cheap like it used to be but its still viable for dealing with the US and many European nations, but we've got some examples from Mr W now to show whats around.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 10:22:24 am
content: Quote from: Rupunzell on June 27, 2016, 03:13:07 amCRTs are no longer used nowadays so that technology is rather obsolete. In the front end part of a scope much remains the same but using different technology (JFET input opamp instead of a discrete JFET) and the input divider also faces the same challenges but when the ADC kicks in the worlds is entirely different. As a coincidence: the (paid ofcourse) project I'm currently working on is a 'simple' DSO for a specialistic purpose.

author: tautech
author_rank: Super Contributor
timestamp: June 27, 2016, 10:28:12 am
content: Quote from: nctnico on June 27, 2016, 10:22:24 amNot available over the counter?Please tell us more.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 27, 2016, 11:13:29 am
content: Quote from: Wuerstchenhund on June 27, 2016, 05:39:48 amI have never reported any posts nor have I seen a reason to. Maybe splitting it up, it seemed like less of a direct attack. I don't think there was anything else in there. I think I had asked if you were in sales. Oh well..Quote from: Wuerstchenhund on June 27, 2016, 05:39:48 amI would guess that you are not alone in not disclosing work stuff. My pile of junk I have at home is only for my hobby. I just happen to actually use it and post from time to time things I build or work on that I think may be of interest. These are way outside of what I do, so there is no conflict of interest. My home business model of buying meters to stress test has not proven profitable so I can't quit my day job anytime soon!I assumed you have some equipment at home for a reason other than to look or make crappy videos of the update rates. This seems like something a person in sales or management would do. Let's see some of these skills you have honed in action!Quote from: Wuerstchenhund on June 27, 2016, 05:39:48 amBastard! I have grown to like the little scope with it's bent up case. It gets used a fair amount and there have been no issues with it. Good to hear you installed that drive and it worked out. If you don't remember, mine was basically an image and removed the swap file. It will be interesting to see when it finally fails. I've had brand new hard drives fail this quick.Quote from: Wuerstchenhund on June 27, 2016, 05:39:48 amI figured this topic was spent. If not, sorry for the detour.

author: rsjsouza
author_rank: Super Contributor
timestamp: June 27, 2016, 11:31:56 am
content: Quote from: tggzzz on June 26, 2016, 09:29:53 pmI shouldn't type these things on a tablet with kids running around... You are absolutely right that both types show an oscillogram that can be interpreted in a similar way. I meant toimproveas in: "(...)given the opportunity they bring to improve the process of interpreting waveforms and skills to get a 'feel' for what is shown on screen."Quote from: nctnico on June 26, 2016, 11:39:28 pmnctnico, you probably missed the disclaimer highlighted above, which brings high end analog scopes to almost the same realm as DSOs, apart from the availability of schematics. As tautech said, a very experienced engineer can venture in doing component-level repair on anything without the schematics, but a beginner will be hopelessly lost and will requirea lotof handholding from eevBlog's forums... That is the point where we agree older test gear is not suitable for beginners.Obviously this particular point is almost irrelevant with equipment that uses discrete or simpler IC technology and has schematics available (my 20MHz Kenwood's circuitry can be read as a book). They can become a great learning opportunity for more advanced hobbyists, which intersects Bernice's point of learning from the circuit itself.

author: tggzzz
author_rank: Super Contributor
timestamp: June 27, 2016, 11:57:29 am
content: Quote from: rsjsouza on June 27, 2016, 11:31:56 amYou'll miss them when they're gone: regret w.r.t. the kids and relief w.r.t the tablet.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 27, 2016, 12:09:37 pm
content: Quote from: joeqsmith on June 27, 2016, 11:13:29 amI certainly can't see any attack in what you posted.Quote from: Wuerstchenhund on June 27, 2016, 05:39:48 amYes, probably.QuoteWell, you've certainly shown some interesting stuff.QuoteYes, I indeed bought the gear for doing some real work other than the occasional demonstration, and I do have a few projects in mind. What keeps me off it is simply a lack of time. Due to my work and status there I work a lot of extended/stupid hours, with a fair amount of travel. On top of that are other duties (i.e. maintaining certain licenses, req'd for work), plus the amount of sleep my ageing body requires, and the truly pittiful rest of time has to be split up between family and friends.The other issue is that, living in a typical British house with shoebox-size bedrooms and a few sqft of garden, I'm currently a little bit space-constrained. We had plans to buy something better but now that the Brits have knifed their economy it would probably pay out to wait as house prices will most certainly fall. If we stay in the UK, that is, as our business is likely to reduce our stake inthe UKEngland, and move most work to somewhere else.Oh well...Quote from: Wuerstchenhund on June 27, 2016, 05:39:48 amYes, it worked absolutely fine, and you're right, the WRXi is a great scope. I also have an Agilent Infiniium DSO8064A (the one in the video where I used it to measure the WRXI's update rate), which was pretty much Agilent's direct competitor to the WRXi Series (both scopes are even from the same era). The DSO8064A is a nice scope (especially after hacking the options) but it really feels like two steps back compared with the WRXi.The main reason I parted with the WR64Xi was that mine had no options, and when I need a scope I mostly just use my WavePro 7300A, which is stuffed with options, so it mostly collected dust anyways. At least I know the new owner will make use of its capabilitiesQuoteSame here, had hard drives fail after a few hours.I also just cloned the original hard drive to the SSD, but I didn't use the SSD's full capacity (left 2GB unused for wear levelling). However, I only disabled background defrag, but I left swap alone.QuoteI concur. Back to topic

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 27, 2016, 12:12:20 pm
content: Quote from: GK on June 27, 2016, 02:29:59 amWhy?

author: coppice
author_rank: Super Contributor
timestamp: June 27, 2016, 01:03:53 pm
content: Quote from: Wuerstchenhund on June 27, 2016, 12:12:20 pmOnly a small number of 7903 and 7904 chassis were purchased with plugins faster than 100MHz, so being able to get 500MHz bandwidth out of one is not the common case. It must have worked out easy for Tek to get 500MHz bandwidth from the chassis electronics and tube, as the chassis wasn't too expensive, but 500MHz plugins were.

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 01:25:18 pm
content: Quote from: coppice on June 27, 2016, 01:03:53 pmMine is currently equipped with a 7A19 and a 7A24 plug-in. The former has a -3dB bandwidth of 600MHz, achieving 500MHz -3dB bandwidth in combination with the mainframe while the latter does 350MHz.

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 01:40:37 pm
content: Quote from: Wuerstchenhund on June 27, 2016, 12:12:20 pmI can see 1GHz on my 7904, it's just that the amplitude is reduced. Furthermore a 1GHz sinewave still looks like a clean 1GHz sinewave, not some time-varying triangular approximation. Think of an equivalent real-time-sampled display that simply satisfies Nyquist for the -3dB bandwidth (1GHz sampling); that will not be the case.To put it another way a significant amount of waveform detail displayed on the CRT of a 500MHz analogue scope can be contained in harmonic components extending significantly beyond 500MHz.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 01:49:51 pm
content: Quote from: GK on June 27, 2016, 01:40:37 pmWhich is why even modern high frequency oscilloscopes have an equivalent time sampling mode. My Tektronix TDS744A and TDS510A (from the early 90's) had >100Gs/s equivalent time sampling and their triggering systems worked well beyond 1GHz and due to the Gaussian roll-off it had no problem at all to work with signals over 1GHz but ofcourse these got attenuated since both are 500MHz scopes.And don't say equivalent time sampling doesn't count because the signal must be repetitive; in order to see any signal stable on an analog scope it has to be repetitive as well.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 27, 2016, 02:20:11 pm
content: Quote from: GK on June 27, 2016, 01:40:37 pmYou don't need 5GSa/s to get a true sample of an 1GHz sine wave, slightly over 2GSa/s (i.e. 2.5GSa/s as offered by some entry-level scopes) is more than sufficient. A higher sample rate will also not result in an increase of details.In addition, to capture a truly repetitive waveform, pretty much any somewhat decent DSO made in the last 20yrs or so can also use ETS/RIS, which increases the effective sample rate to somewhere between 10GSa/s and 200GSa/s.QuoteAny DSO that satisfies Nyquist-Shannon, i.e. which samples at least at 2.2GSa/s, adequately resolves a 1GHz sine wave.QuoteThat's also true for DSOs, which often have an analog bandwidth much larger than what is specified. For example, the elsewhere mentioned 600MHz WR64Xi had a measured bandwidth of slightly over 1GHz, and my 600MHz Agilent DSO8064A has been measured with a BW of 1.25GHz. The latter one also has a max sample rate of 4GSa/s, and even that is enough to appropriately resolve the true analog bandwidth.Asking for a 5GSa/s sample rate for 1GHz BW is nonsense.

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 02:31:50 pm
content: Quote from: Wuerstchenhund on June 27, 2016, 02:20:11 pmSorry, but you don't know what you are talking about. Why do you think that reputable manufacturers like Lecroy make DSOs with real-time sampling rates ten times the -3dB (analogue) bandwidth if it is "nonsense" even to sample at five times the BW?A "2.2 GHz" sampling rate will not accurately reproduce a 1GHz sinewave unless there is a brick-wall anti-aliasing filter/re-construction filter, which there isn't. This is not analogous to digital audio.

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 02:37:24 pm
content: Quote from: nctnico on June 27, 2016, 01:49:51 pmI won't say that ETS doesn't count, but it still comes with limitations. I regularly view non-periodic but repetitive waveform bursts at 1nS/div on my 7904 that would potentially play havoc with ETS; there are also triggering limitations.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 02:42:33 pm
content: Quote from: GK on June 27, 2016, 02:31:50 pmBecause they use the same sampling hardware for various bandwidth models. Every DSO manufacturer does that!Anyway discussing signal components far beyond the bandwidth is moot because there will also be phase shifts due to the various components doing the filtering (either on purpose or by functional limit).

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 02:52:35 pm
content: QuoteYeah right, that's all there is to it.Quote from: nctnico on June 27, 2016, 02:42:33 pmThis response was entirely predictable and quite wrong. I've identified/found 1GHz and slightly higher instabilities on my 7904 that would have been lost on an equivalent analogue-bandwidth DSO without the sampling rate to properly resolve these signals.

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 03:11:34 pm
content: Quote from: GK on June 27, 2016, 02:52:35 pmI've read that before but for once I'd like to see the proof why such signals would be lost on a DSO. If the signal is visible then it will be picked up just the same. You'll see an irregulatity in the signal (part of the signal won't 'converge' into a waveform in ET mode) just like on an analog scope.

author: GK
author_rank: Super Contributor
timestamp: June 27, 2016, 03:28:20 pm
content: Quote from: nctnico on June 27, 2016, 03:11:34 pmA 1GHz oscillation burst is more faithfully transcribed and much more readily discerned if it is sampled at 5GHz rather than 1GHz. I don't think that this should be a contentious fact.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 27, 2016, 03:47:02 pm
content: CRTs are still used in the Photonics industry as image converters, micro channel plate image intensifiers and more. Other CRT variants include photo multiplier tubes and IR imager tubes. Much like speciality RF and Microwave tubes, these vacuum tubes have no solid state equivalent. CRTs are no longer used in mass market displays does not mean CRTs are an obsolete technology, that technology has migrated to where it is most effectively used and applied.For those who labor under the mis-guided belief Op-Amps can replace all discrete device amplifiers, this is another mis-guided idea and belief. We have had this discussion once before on eve-blog under a different heading. Rather than drag out those previous barbs, it would be far better to allow discovery of what limitations of Op-Amps are and can be. What is fact, there are no Op-Amps that can ever replace speciality discrete device amplifiers in high performance analog systems..... This is quickly encountered and realized once any higher performance data acquisition system is attempted.Simplest form of a DSO could be a single analog to digital converter (signal conditioning & filtering included) streaming data to a host computer with display. Even more rudimentary would be a Digital Volt Meter or any similar conversion device. Given the large number of devices easily available on the market today, is there retinal justification to design a, "simple DSO" even if it is a specialty item?What is clear based on what has been written, these are ideas based on cook book systems designs that are essentially picking building blocks much like Lego blocks then slamming them together using simulation software to predict what and how the completed system might work, As the system is put together as a real word device, problems are encountered limiting the potential system performance or numerous other problems occur due to design myopia.Design excellence rarely happens using this methodology.BerniceQuote from: nctnico on June 27, 2016, 10:22:24 am

author: nctnico
author_rank: Super Contributor
timestamp: June 27, 2016, 04:36:22 pm
content: Quote from: Rupunzell on June 27, 2016, 03:47:02 pmI agree; sometimes I take the discrete device route myself.QuoteYes. The DSO I'm working on is 'just' a signal monitoring feature in a large data acquisition system to be used in (electrically) very harsh environments. I'm not designing the entire system (only doing FPGA and wireless power) but there are very few manufacturers of this particular kind of systems.

author: joeqsmith
author_rank: Super Contributor
timestamp: June 28, 2016, 12:37:04 am
content: I think Duddell had it right. Forget the CRT.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: June 28, 2016, 05:42:11 am
content: Quote from: GK on June 27, 2016, 02:31:50 pmReally?Here's a 1GHz sine wave sampled @ 20GSa/s:Here at 10GSa/s:Here at 5GSa/sHere at 2.5GSa/sHere at 1GSa/sThat's a 1GHz signal from an Anritsu MG3700A Vector Signal Generator fed into a 3GHz 20GSa/s LeCroy WavePro 7300A scope (the BNC cable I used had a flaky connector which resulted in slight amplitude variations but I couldn't be bothered to unpack a new cable).I guess we agree that it's obvious why the 1GSa/s screenshot looks like shit, so please go ahead and point out to me the additional details you believe you see on the shots sampled at 5GSa/s and higher vs the 2.5GSa/s shot.Yeah, there aren't any.Next time, before you tell others they don't know what they're talking about, I recommend you get a at least a basic understanding of waveform math and signal physics, because the simple fact is that a continuous-time sine wave that is sampled at >2xf0can truly reproduced using sin(x)/x interpolation, and any increase in sample rate will not result in additional details. The math behind it doesn't lie.Quote from: GK on June 27, 2016, 03:28:20 pm(emphasis mine)Yes, a 1GHzburstrequires a higher sample rate than 2.5GSa/s (or 5GSa/s, for that matter), as due to its non-continuous properties it will contain frequency components that are much higher than f0. But it also requires an analog bandwidth of a lot more than 1GHz, so the 7904 is utterly useless for such signals. You might seesomething, but it won't have much to do with how the input signal really looks like.QuoteSimple, really:- As nctnico said, most scope series contain higher bandwidth models, and a 1GHz scope requires a faster sampling rate than the 350MHz model. You'll also find that for some scope series, the lower BW models come with a much lower sample rate (i.e. the LeCroy WaveRunner2 LT, WR6k(A), WR6zi, WP7Zi(-A))- Higher than required sample rates allow the use of oversampling techniques to increase vertical resolution to up to 16bit (i.e. R&S RTE, RTO Series)- While low-end scopes usually use standard components for ADCs, mid-range and high-end scopes usually use ADC hybrids that are inhouse developments of the scope manufacturers, which makes them pretty expensive. To keep costs down, they are often re-used across scope ranges, with as few as possible variants- A high sample rate looks impressive on the spec sheet

author: GK
author_rank: Super Contributor
timestamp: June 28, 2016, 07:01:29 am
content: QuoteYAWN. I was specifically NOT talking about interpolation processing (that ruins the fluidity and real-time display of a complex, varying waveform).QuoteBollocks to the nth degree. Even in an ideal case it is only the first and last cycles of a 1GHz burst of several cycles is significantly corrupted in a 500MHz bandwidth (the bandwidth for the transition in and out of DC is theoretically infinite, but the rest of the cycles pass for all sakes an purposes unscaved).I recently had one very such HF burst - occurring right at the crest of a ~200MHz fundamental-f arbitrary but periodic and repetitive waveform. It was due to op-amp oscillation. Only a handful of cycles. This instability was clearly visible on the 7904 and when I dialled the timebase setting down to 1ns/div and fiddling a bit with the trigger I could easily make a ~+/-10% measurement of the frequency of instability right off graduated graticule. How, pray tell, oh wise and all-knowing one, does that make my 7904 "utterly useless for such signals"?

author: GK
author_rank: Super Contributor
timestamp: June 28, 2016, 08:26:17 am
content: Quote from: Wuerstchenhund on June 28, 2016, 05:42:11 amETS, RIS, linear and sin(x) interpolation are not substitutes for greater than Nyquist sampling, they are workarounds for when you need to compromise. They all come with limitations and potentially severe shortcomings (if not used wisely) which simply do not exist when you can sample sufficiently far above Nyquist.It is not mere marketing, “specsmanship” and hardware rationalization that DSOs with sampling rates well above Nyquist exist. All else being equal, a 500MHzBW-1GSa/s DSO is not an equally versatile and capable high frequency measuring instrument as a 500MHzBW-5GSa/s DSO.

author: tggzzz
author_rank: Super Contributor
timestamp: June 28, 2016, 08:45:24 am
content: Quote from: Rupunzell on June 26, 2016, 05:17:54 amUnfortunately understanding is not highly prized.As for DSOs being easier to interpret, easier to make measurements, and easier for a beginner to understand, have a look at the screen dump in the link below. I would hope and expect that even a beginner might question the measurement. But what about a less obviously "suboptimal" measurement that might be lurking?https://www.eevblog.com/forum/beginners/my-new-(i-suspect-faulty)-ds1054z/msg963322/#msg963322Please don't let this degenerate into a "what do you expect for $400" discussion. My point is about the need for understanding.

author: Fungus
author_rank: Super Contributor
timestamp: June 28, 2016, 09:28:51 am
content: Quote from: tggzzz on June 28, 2016, 08:45:24 amHopefully even the greenest of newbies would realize there's no wires connected to channel 2's input BNC, that maybe the number can be ignored.Yeah, it's not a great feature but picking up AC mains (or whatever) is to be expected whenever you have a floating input to a very sensitive op-amp.The 'bug' isn't in the number on screen, the 'bug' is that it doesn't simply display zero whenever ground coupling is enabled (would that be cheating?)Quote from: tggzzz on June 28, 2016, 08:45:24 amIf there were any other "suboptimal" measurements? I'm sure you'd be posting them here every five minutes.

author: tggzzz
author_rank: Super Contributor
timestamp: June 28, 2016, 09:45:44 am
content: Quote from: Fungus on June 28, 2016, 09:28:51 amIn the context of that screendump, I cannot see the relevance of either statement.QuoteMeasurements of DC and sinusoidal waveforms are trivial on either an analogue or digitising scope. Where a DSO's measurement capabilitiesoughtto be a significant advantage are in more complex waveforms, e.g. non-sinusiodal and/or with various forms of noise.With such waveforms I don't know how I would notice a 10% error, let alone a beginner.

author: Fungus
author_rank: Super Contributor
timestamp: June 28, 2016, 10:58:10 am
content: Quote from: tggzzz on June 28, 2016, 09:45:44 amYetyouposted the screendump as evidence of something?

author: joeqsmith
author_rank: Super Contributor
timestamp: June 28, 2016, 11:09:31 am
content: " have a look at the screen dump in the link below. " Read his post.Quote from: Fungus on June 28, 2016, 10:58:10 am

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 28, 2016, 11:29:29 am
content: Quote from: Fungus on June 28, 2016, 09:28:51 amof coarsealso engineers want to smile sometimes.

author: tggzzz
author_rank: Super Contributor
timestamp: June 28, 2016, 11:37:29 am
content: Quote from: joeqsmith on June 28, 2016, 11:09:31 amQuite. I don't think he had had his first dose of caffeine

author: rsjsouza
author_rank: Super Contributor
timestamp: June 28, 2016, 11:44:43 am
content: Quote from: tggzzz on June 28, 2016, 08:45:24 amA bit more subtle error that emphasizes the importance of correctly interpreting the waveform on screen before blindly trusting measurements is in the snip of one of my videos below:https://youtu.be/mw9H1NinDeQ?t=23m14sI suspect that chances are higher that a less experienced user will suspect the signal source is wrong simply because "the number" tells it so.

author: tggzzz
author_rank: Super Contributor
timestamp: June 28, 2016, 11:51:07 am
content: Quote from: rsjsouza on June 28, 2016, 11:44:43 amWow. That's ... um, surprising.Any idea what causes it? (My Spanish isn't up to understanding anything you say!)

author: nctnico
author_rank: Super Contributor
timestamp: June 28, 2016, 12:42:06 pm
content: I did some tests with a 2.1GHz burst (8us burst, 50ms silence) fed into a 1GHz 2Gs/s scope in ET mode. In the first one I forgot to switch the probe factor back to 1:1 because the signal is fed in from a 50 Ohm source.

author: Fungus
author_rank: Super Contributor
timestamp: June 28, 2016, 12:58:07 pm
content: Quote from: tggzzz on June 28, 2016, 11:37:29 amThe first clue is in the tiny symbol shown on channel 2. I know it's small so I've highlighted it here:That seemsveryrelevant to my second statement:"the 'bug' is that it doesn't simply display zero whenever ground coupling is enabled"Understanding the rest of it will mean you have to read the entire thread where this issue was discussed. Bummer, right?

author: rsjsouza
author_rank: Super Contributor
timestamp: June 28, 2016, 06:30:58 pm
content: Quote from: tggzzz on June 28, 2016, 11:51:07 amMy best idea is that the amplitude was too low for the frequency counter to trigger properly, but I didn't think about that the day I shot the video nor I remember now.BTW, you were close... the language is Portuguese and I can babble as much as Dave.

author: tggzzz
author_rank: Super Contributor
timestamp: June 28, 2016, 07:31:42 pm
content: Quote from: rsjsouza on June 28, 2016, 06:30:58 pmDamn! I looked at "souza", considered Portuguese, and rejected it because of the US flag!

author: vk6zgo
author_rank: Super Contributor
timestamp: June 28, 2016, 11:40:00 pm
content: Quote from: Wuerstchenhund on June 28, 2016, 05:42:11 amA burst does not necessarily contain "muchhigher frequency components" than a CW signal of the same frequency.It is all dependent upon the envelope shape of the burst.For instance,the 4.433MHz colour burst in PAL TV contains very little harmonic energy--line & field rate sidebands,yes,harmonics no.OK,that is a specially "tailored" envelope,but naturally occurring intermittent bursts of oscillation tend to build up over time,rather than just suddenly appear full amplitude,with the result that the envelope rise is also fairly gradual.Add to this,the frequency limitations of the circuit the problem appears in,& those "much higher frequency" components will be well attenuated before you go anywhere near it with an Oscilloscope.

author: G0HZU
author_rank: Super Contributor
timestamp: June 29, 2016, 03:23:50 pm
content: QuoteQuoteQuoteA high sample rate is good for various reasons and one of them is to prevent alias terms from corrupting the displayed waveform. A typical 500MHz scope will have a graceful frequency rolloff with flat group delay so the amount of alias rejection will be limited if the sampling rate is only 2 or 3GHz. Therefore, if I had to choose a DSO to replace a 500MHz analogue scope and I wanted the same frequency (and flat group delay) response then I'd want a high sampling rate to minimise the influence of alias terms when looking at complex waveforms that have spectral content up in the GHz region.So I think 5GHz sampling would be a good/safe choice. Go down to 2.5GHz sampling and I think that the alias effects will begin to degrade the display of the wideband waveform compared to what you would see on the analogue scope. I guess it depends on how accurate you want the display to be? Some people will be happy to live with the degraded display at the lower sample rate. They might not care if it isn't quite right and the degradation is negligible to them?The other option would be to choose a scope with a steeper filter rolloff (eg max flat response) as this will be less prone to alias issues. So you could use a lower sample rate and have less problems with alias terms. But this won't have the same frequency response characteristics as the analogue scope. It's up to the user to decide if this is a good/bad thing for the range of things they want to use the scope for.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: June 29, 2016, 03:59:03 pm
content: Heading down a road previously traveled...https://www.eevblog.com/forum/testgear/recommendation-request-new-rigol-ds1054z-or-used-tektronix-2467bhd/msg798701/#msg798701https://www.eevblog.com/forum/testgear/my-first-oscilloscope/msg645726/#msg645726Little if anything has changed.Bernice

author: rsjsouza
author_rank: Super Contributor
timestamp: June 29, 2016, 07:43:52 pm
content: Another thing that usually does not change...Quote from: KJDS on April 05, 2015, 09:03:29 am

author: nctnico
author_rank: Super Contributor
timestamp: June 29, 2016, 09:50:07 pm
content: Quote from: G0HZU on June 29, 2016, 03:23:50 pmThe older digitizing scopes like the Tektronix TDS500/700 series DSOs (and probably others) typically have such a Gaussian roll-of but these use equivalent time sampling to overcome the limits of their sampling rates (500Ms/s to 2Gs/s). For looking at the waveforms you are suggesting they work just as well as an analog scope WITH all the benefits of a DSO.

author: GK
author_rank: Super Contributor
timestamp: June 30, 2016, 01:00:38 pm
content: Quote from: G0HZU on June 29, 2016, 03:23:50 pmModern DSOs with lower sampling rate to -3dB bandwidth ratios (say only 4:1) have tailored, non Gaussian responses which flatten the response prior to the -3dB point, but provide a steeper roll off and greater attenuation afterwards. This helps prevent/minimize aliasing issues, even when using sinx(x) interploation. This modified response is discussed in that article joeqsmith linked to; where the traditional (Gaussian) relationship BW=0.35/RT no longer holds. I suggest a 500MHzBW-5GSa/s speced DSO as an equivalent "real time" performer to my 500MHzBW 7905 as this is the kind of DSO that is most likely to have an analogue frequency response beyond -3dB best matching that of the old analogue. Additionally, I did not cite 1GHz as the highest frequency visible on the CRT of a 7904. It just is what I have actually seen and it also happened to be a convenient figure to quote because I was completely anticipating being otherwise duly informed that a 500MHz DSO only needs a 1GSa/s sample rate (due to what Nyquist allegedly says) to display anything that my beloved 7904 can. I'm sure that my 7904 is already rolling off at more than a -6dB rate by 1GHz, but I wouldn't be surprised if I could see significantly further than this if I had a test signal source of such frequencies handy. That visible ~1GHz parasitic op-amp oscillation I mentioned was from an old GHz-GBWP part #"CLCxxx" (Comlinear corporation?) CFA (in a DIP!) that I dead-bugged as a voltage follower with too small a feedback (f-compensation) resistor between the output and the inverting input pin, so it wasn't entirely happy. Come to think of it I might borrow one of our 3G radio telemetry/data modems from work with an SMA-to-BNC adaptor. Incidentally at a sampling-to-bandwidth ratio of 10:1 or more sinx(x) interpolation is mostly superfluous. An old boat-anchor DSO with that ratio need only have the processing power for passable-performance linear interpolation.Incidentally#2: The distributed deflection plate CRT system of the 7904 is -3dB at ~1GHz on its own. I forget the model number but Tek made a passive vertical "amplifier" plug-in that was installed by disconnecting/bypassing the vertical amplifier in the mainframe, connecting the passive plug-in directly to the deflection plates. You needed a soldering iron to do the installation. The specified vertical bandwidth was then 1GHz min. but there was obviously not much flexibility in the sensitivity.

author: G0HZU
author_rank: Super Contributor
timestamp: June 30, 2016, 03:14:18 pm
content: Quote from: nctnico on June 29, 2016, 09:50:07 pmYes, I have an old HP 54540C here (500MHz 2Gs/s) and it has a mode called 'Repetitive' and I assume that this is a form of ETS. I've not used this scope much but the repetitive mode seems surprisingly useful. I expected it to be a fussy waste of time but it copes quite well with quite a range of waveforms. Obviously, ETS can/will fall over on lots of waveform types but on an old scope like this it does help a lot sometimes.

author: Martin.M
author_rank: Frequent Contributor
timestamp: June 30, 2016, 03:19:11 pm
content: Quote from: GK on June 30, 2016, 01:00:38 pmthis means a 7A21N (N of coarse, a passive input can`t generate any readout)7A21N is not more useful then a good restorated 519greetingsMartin

author: G0HZU
author_rank: Super Contributor
timestamp: June 30, 2016, 03:38:29 pm
content: QuoteYes, I'd agree with that. However, I'm really not a scope guru or enthusiast so I only know the basics about any potential tradeoffs wrt sampling/filtering/adc/interpolation/etc when choosing the right DSO for a task.Here's some basic info about my old HP54540C. This isn't a scope I'd recommend to most people for various reasons but it has 2Gs/s and a 500MHz BW when used on a single channel.The frequency response does look to have a gradual rolloff and if I put it in repetitive mode and stick a sig gen into it the response falls by about 17dB by 1300MHz. It still displays and measures the frequency correctly in this 'repetitive' mode. But 1300MHz is obviously way past the Nyquist limit for 2Gs/s when in real time mode.I really don't think you would be impressed by this DSO if you saw it in real time mode when trying to display a 500MHz sinewave. It looks bad in real time mode once you get up above 300MHz. I assume the interpolation struggles a bit here as there is a lot of wobble on the signal. However, I don't have another one to compare it to so this degree of wobbliness may be a slight fault.It's not a nice scope (or a great performer) overall although it has some powerful analysis modes and the keypad system is very powerful/useful with the blue shift key. The fan noise is particularly annoying as it emits a low pitched drone from the back that easily dominates all my other test gear. I don't think the fan is worn or faulty, I just think the size of the fan and the overall scope enclosure gives it this droning quality. I salvaged it at work as it was destined for the skip. Nobody else wanted it and I think I now know why

author: Jwalling
author_rank: Unknown
timestamp: June 30, 2016, 05:14:19 pm
content: Quote from: G0HZU on June 30, 2016, 03:38:29 pmI'd be very surprised if you couldn't upgrade that scope to a 54542C and sample @ 2Gs/s on all four channels simultaneously. That scope uses the same attenuators and A/D FISOs that are on the 54810A through 54825A scopes. See a post I made to the HP/Agilent group on Yahoo a while back:https://groups.yahoo.com/neo/groups/hp_agilent_equipment/conversations/messages/60910You'll have to look around to find the strapping resistor - look for a 50MHz oscillator for starters. If you'd like, I'll have a look at a 54542A ACQ board I have in my scrap pile and see if I can identify where it's located. Let me know...Jay

author: G0HZU
author_rank: Super Contributor
timestamp: June 30, 2016, 05:57:05 pm
content: Quote from: Jwalling on June 30, 2016, 05:14:19 pmYes, I'd be interested in this, thanksI did have a look through the firmware a while back to see if it could be done this way but I think it would be too time consuming to work out the code changes. The hardware does look to be very similar in the documentation.I've not taken the covers off it so I don't know how accessible all this stuff is but I really should take it apart to check the PSU caps for leakage etc.If the upgrade is possible then it would be nice to get the full performance on all 4 channels.I'm not too worried about bricking it if things go wrong. It didn't cost me anything.

author: Jwalling
author_rank: Unknown
timestamp: June 30, 2016, 06:28:43 pm
content: Quote from: G0HZU on June 30, 2016, 05:57:05 pmOK, My money would be on R744. Note the bit of dicking about on the solder - it looks like there was a resistor there at one point. R745 also appears to have been removed - not sure about this one. There's only about five resistors with reference designations, the rest have nothing. Very telling, in IMHO.Messing with these resistors will be more difficult than on the 548XX scopes where all you have to do is remove the cover. You'll have to pull the ACQ board, which is about a 30+ minute job depending on your expertise in this particular scope. IOW a PITAEDIT: (trimmed), One thing- I'm not completely sure this is a 54542A and not a 54540A, but looking at your ACQ board will reveal a difference, hopefully.Jay

author: G0HZU
author_rank: Super Contributor
timestamp: June 30, 2016, 08:28:10 pm
content: Thanks for the info and the closeup imageI wonder if some of the labelled resistors may be select on test resistors to optimise something during production test? The value of R703 (and the shape of the PCB track it connects to looks a bit odd for something that is a config resistor.I'm assuming that the idea is to change a clock multiplier to step up the sampling rate?There's an image of the 54540C board on a current ebay auction. it says 542 in places on the board but it has a white 54540 sticker on the PCB edge.http://www.ebay.com/itm/54540-66511-Main-PCB-for-HP-54540C-/261677319734?hash=item3ced2f0636:g:5-wAAOSwubRXIiV0I'll have a close look at it and I'll have a look in the manual to see how easy it is to take it all apart.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 01, 2016, 05:50:37 am
content: Quote from: GK on June 28, 2016, 07:01:29 amNo, it doesn't, unless your DSO is from the 90's. Pretty much every somewhat modern DSO reaches high waveform rates when using sin(x)/x, and that includes entry-level scopes like the Agilent/Keysight DSO-X2k/3k, or cheap ones like the Rigol DS2000 (all which aren't even new designs).Quote from: G0HZU on June 29, 2016, 03:23:50 pmThat is true for low bandwidth DSOs (<=350MHz) which usually come with a Gaussian frequency response similar to analog scopes, however most 500+MHz real-time DSOs have a flat response with brick wall like sharp rolloff at the top end. A typical 500MHz DSO will have a -3dB point at somewhere between 700MHz and 1GHz, with a cut-off I'd expect at some where below 1.2GHz (which only requires fs>2.4GSa/s)QuoteI agree, however there is is no point in a sample rate that is higher than what's required to resolve the highest frequency component your scope can actually "see", which slightly over 2x f0. Anything higher will not result in additional details (as clearly visible in the example screenshots I posted), all it does is filling up your sample memory more quickly.On a DSO, rather than an excessive sample rate, it's important to have a large enough sample memory to avoid dropping your sample rate (and therefore your usable real-time bandwidth) on longer time bases.QuoteOn a 1GHz BW signal? No, it wouldn't, as demonstrated.QuoteAssuming they even understand the real degradation and don't assume that, just because something is visible on the screen, that this is necessarily a true representation of the input signal.Operating test gear in the border areas of its specifications or confirmed performance envelope isn't really a good idea.QuoteDon't forget that the 7904 vs DSO discussion was about a 1GHz sine wave initially, and a true continuous-time 1GHz sine wave is, by nature, BW limited. And as demonstrated, there's zero use in sampling a 1GHz sine wave at more than 2.5GSa/s.And as staed above, the other question is how much use is in using a scope, especially one with Gaussian response, beyond it's rated (specified) BW, considering how the vastly attenuated and potentially phase-shifted frequency components in the border areas of it's frequency response very likely results in a distorted waveform on the screen, something that is also true for analog scopes. Especially if the true performance beyond the specified 500MHz BW has never been properly measured/assessed, as it seems to be the case with GK's Tek 7904.

author: GK
author_rank: Super Contributor
timestamp: July 01, 2016, 07:08:46 am
content: QuoteAnd a DSO from the 90's or a bit later was the context of my original comment and is specifically the era of a now well used / second hand DSO that could be had to match the equivalent real time performance of my 7904 (from the '70s) for about the same investment in $. An "entry level" scope like the DSOX3k with 500MHz analogue bandwidth is currently listed at $15,224 AUD. The DSOX2k series starts at a fraction under $5k AUD and doesn't get close to 500MHz. The DS2000 series while much cheaper than the Keysight only goes to 300MHz. A high BW to sampling rate ratio simply gives acceptable "real time" linear interpolation performance with limited processing power and a lot of these old DSOs didn't even have sinx(x) interpolation.Quote**without** reconstruction filteringQuoteThis is starting to get repetitive and boring. I don't think that anyone serious would dismiss the utility or fail to grasp the usefulness of still being able to identify parasitic oscillation and interference signals significantly beyond an oscilloscopes specified -3dB bandwidth. And I can assure you, a 7904 can "see" beyond 1GHz, which is only one octave beyond 500MHz.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: July 01, 2016, 09:04:58 am
content: Tek 7104, 7A29, 7B10@ 1Ghz:@2Ghz, on the threshold of loosing trigger.@3Ghz, amplitude still visible, loss of trigger.Tek 7904 or 7904A will still display a 1Ghz sine and a bit beyond with the amplitude reduced, loss of trigger with increasing input frequency decreased CRT display intensity (this is where the MCP on the Tek 7104 makes it a bit special). Been there done this.Much of this is mostly pointless and moot as the individual involved simply does not understand or value what time domain instruments of this type have to offer that is factually better than a DSO in specific applications. This example goes far beyond simple time domain instrument frequency-amplitude response, there will be probes, connections and test set ups involved which will have an effect of information presented on the time domain instrument display.... It is up to the user to interpret and believe or dis-believe what is presented on that display. If one were to play the utter Ghz game, it is possible to mix down or down convert said sine wave and filter as needed to display Ghz sine waves as needed. There are also sampling systems for the Tek 7000 that will easily go well into the Ghz range given the signals are repetitive. The other extreme is to put in a Tek 7A22 which goes down to 10uV/Div @ 1Mhz, how many modern DSOs or any DSO can do this stand-alone without external help?The market need for 5, 10 and beyond Ghz DSO's are driven by the Ghz data rate common in data transmission and digital stuff in general today, BUT not all of electronics is about Ghz data. As been previously mentioned to Ad nauseam, this obsession with DSO or Analog CRT absolutely depends on the application. It is also abundantly clear, many DSO users rely on the data box and converted data to interpret the information presented rather than understanding and developing the visual skills required to properly interpret the wealth of information available in a proper CRT display. The data box and covered data approach fits in nicely with design by 'puter software which tends to add an isolation layer to the design process.Now ponder how many home electronics folks are going to tinker with several Ghz data and similar systems? Just trying to probe a system like this without altering system behavior is not going to be simple.And no, trying to convince an individual with a over blown ego of an alternative factual reality to what that individual WANTS to BELIEVE.BerniceQuote from: GK on July 01, 2016, 07:08:46 am

author: Fungus
author_rank: Super Contributor
timestamp: July 01, 2016, 09:42:07 am
content: Quote from: Rupunzell on July 01, 2016, 09:04:58 amYep. Buying the 'scope is only the first tiny step to measuring 1GHz+ signals.

author: GK
author_rank: Super Contributor
timestamp: July 01, 2016, 09:43:41 am
content: Quote from: G0HZU on June 30, 2016, 03:38:29 pmThis is exactly the kind of thing I had in mind. That scope is typical of its age and it isn't optioned with and/or doesn't have the processing power for fluid/fast proper-sinx(x) interpolation/reconstruction filtering as seen on modern DSOs. Yes, 500MHz will not look pretty with only 4 sample points per period and what is likely just some form of linear interpolation. The "wobble" you report is normal as the sampler isn't phase-locked to the displayed sinusoid. 200MHz with ten sample points likely looks quite acceptable though. On that model I believe if you turn off interpolation you just get a display of the raw sampled data points as dots? If that DSO had a sampling rate of 5GSa/s rather than 2GSa/s then it would compare much more favorably to the 7904 in terms of equivalent real-time performance and the displayed fidelity of high-frequency waveforms.

author: nctnico
author_rank: Super Contributor
timestamp: July 01, 2016, 09:55:46 am
content: Quote from: Fungus on July 01, 2016, 09:42:07 amYou can make a very simple 1GHz probe from a BNC to BNC adapter for a few dollars/euros. Secondly you don't really probe signals over 1GHz; you put a coupler or passive divider on the board which has an SMA (or similar) plug you connect to your oscilloscope.

author: Fungus
author_rank: Super Contributor
timestamp: July 01, 2016, 09:59:40 am
content: Quote from: nctnico on July 01, 2016, 09:55:46 amBut you still need to know a lot about electronics, sampling theory, signal reconstruction, etc., to interpret what you're seeing on screen.The oscilloscope is just a tool, not a solution.

author: nctnico
author_rank: Super Contributor
timestamp: July 01, 2016, 10:05:06 am
content: Quote from: Fungus on July 01, 2016, 09:59:40 amI wouldn't say you need to know a lot but as usual you need to have an idea about what kind of signal/reading you should get. This goes for any piece of test equipment. For example figuring out a DMM is set to AC when you see 0V while expecting to see a reading around 10V DC.

author: Jwalling
author_rank: Unknown
timestamp: July 01, 2016, 10:42:38 am
content: Quote from: G0HZU on June 30, 2016, 08:28:10 pmOK. Here's a few more close-ups. Yes it's a 54542A board, it would helped if I had only LOOKED at the damn sticker.The sticker reads 54542-66507. Underneath the sticker in etch, it's 54542-66501. On the second picture, the area highlighted is on the component/otherside of the board where the resistors are. I wonder if you could get wangs_trading to take a good close-up picture of the area in question - that would save you some time.EDIT: That last picture of the solder-side in that Ebay listing is close but no cigar... Just a zoom in on the area with the ceramic hybrid would do the trick!Jay

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: July 01, 2016, 10:59:32 am
content: Quote from: GK on July 01, 2016, 07:08:46 amHey, something wecanagree onQuoteAs I said, I'm not doubting it can "see" it. My doubts lie within its capabilities to accurately represent the original signal on the screen. Have you actually measured it's frequency response and phase accuracy beyond the specified 500MHz? How does the response curve look like?It would be really interesting to see some examples (screenshots, or a video) of how the 7904 performs at complex signals >1GHz, with the signal split between the 7904 and a capable high bandwidth DSO (as a reference how the input signal really looks like).

author: Someone
author_rank: Super Contributor
timestamp: July 01, 2016, 01:02:32 pm
content: Quote from: Rupunzell on July 01, 2016, 09:04:58 amA specialty plugin is not really "part of the scope", its entirely comparable to the (also Tek) ADA400:http://www.tek.com/datasheet/ada400a-differential-preamplifier-datasheetThough I've seen companies hold onto 7000 series mainframes just to use the plugins (using the channel output into a sampling DSO!). Having used 7A22's I was very motivated to get an ADA400 and modify it for use on modern scopes.

author: G0HZU
author_rank: Super Contributor
timestamp: July 01, 2016, 04:07:03 pm
content: QuoteLiterature from Agilent suggests that it is typical for scopes of <= 1GHz BW to have a Gaussian rolloff.Earlier you posted up some plots from your Lecroy scope showing the interpolation performance vs sample rate for a sine wave signal at 1GHz. Can you post up a brief (smartphone?) video of the 2.5Gs/s plot with the 1GHz sinewave to your youtube page to show us the 'fidelity' of the sine wave across numerous waveforms? How much wobble does it show on a video rather than a single shot screen grab?Then maybe someone can do the same with a decent analogue scope. I expect the analogue scope to look good and I expect your scope to look a bit wobbly at 2.5Gs/s.A picture is worth a thousand words but in this case I think a video will be worth even more.

author: G0HZU
author_rank: Super Contributor
timestamp: July 01, 2016, 04:09:39 pm
content: QuoteThanks for posting up more images.To me it looked like the PCB artwork was subtly different in various places on the ebay picture. Is the artwork for some of these resistors even there?

author: Jwalling
author_rank: Unknown
timestamp: July 01, 2016, 04:40:20 pm
content: Quote from: G0HZU on July 01, 2016, 04:09:39 pmWell, for one thing, the 54540C had an LCD interface while the A models had a vertically-mounted HV CRT board. That would account for a huge difference on the processor (left) side of the board. The area of concern around that hybrid in that Ebay listing looks the same, but the detail level just isn't good enough to make out what's what.Jay

author: David Hess
author_rank: Super Contributor
timestamp: July 02, 2016, 06:38:41 am
content: Quote from: Someone on July 01, 2016, 01:02:32 pmI like using the 7A13 with the 7000 mainframe's vertical output into a DSO and I even ended up making simple improvements in my 7603 to lower the output noise of the vertical output by 20+ dB. The improvements are documented somewhere on the forum here with suggested improvements and I would have linked them but the useless search function failed me.But the 7A13 is another plug-in to go along with the 7A22 where if you have to ask for the modern replacement, you cannot afford it; the ADA400 from Tektronix is a $2000 dollar item and the 7A13 equivalent from LeCroy originally made by Preamble is similarly expensive. On the other hand, I can find working 7A22s on the used market for less than $100 each and AM502s (a closer match to the ADA400) for not much more. I ended up with two 7A22s and one AM502 just buying other plug-ins and mainframes.Your comment about the vertical output reminded me of another analog oscilloscope function which cannot be replicated with a DSO or at least a modern one, the trigger (gate on an analog oscilloscope) output. Last time I checked, even Rigol was avoiding the term trigger output and I assume it was because it was misleading and someone in marketing was feeling unusually honest. I can use the gate output to trigger a modern DSO but I can't use the trigger output of a modern DSO to trigger an analog oscilloscope without massive jitter. I admit however that this function is useless to a vast majority of users although it may be one of those functions like differential comparator slideback operation where you never realize what it can do until you see it in action.

author: Someone
author_rank: Super Contributor
timestamp: July 02, 2016, 06:54:09 am
content: Quote from: David Hess on July 02, 2016, 06:38:41 amThe ADA400 is available easily second hand so prices for all the options are similarly in the couple of hundred dollars. Once you've used these functions you sure get used to having them aroundTry a curve tracer some time!

author: GK
author_rank: Super Contributor
timestamp: July 02, 2016, 07:33:01 am
content: Quote from: Wuerstchenhund on July 01, 2016, 10:59:32 amI don't recall stating that a 7904 will accurately transcribe a waveform with a 1GHz fundamental component, which it obviously won't. In your selective quoting you missed by prior sentence:"I don't think that anyone serious would dismiss the utility or fail to grasp the usefulness of still being able to identify parasitic oscillation and interference signals significantly beyond an oscilloscopes specified -3dB bandwidth"

author: David Hess
author_rank: Super Contributor
timestamp: July 02, 2016, 07:39:59 am
content: Quote from: Someone on July 02, 2016, 06:54:09 amThings I never really understood the utility of until I used them include dual delta delayed sweep, alternate sweep in various forms, slideback measurements, and gate B output.As far as curve tracers, I have a 7CT1N. It is not much but it works. One of my 7A22s came with the curve tracer.When I was evaluating a Tektronix MSO5000 series I asked one of the application engineers if it could do the equivalent of dual or delta delayed sweep or even alternate sweep. He was sure it had the equivalent of one of those capabilities but even between the two of us we just could not get it to happen. We did manage to get the oscilloscope into an unrecoverable state requiring a reset though.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: July 02, 2016, 08:20:27 am
content: Like this, using time base A triggered on Right Vertical, time base B triggered on Left vertical both running at different sweep rates and triggered independently. Effectively two individual O'scopes in one Tek 7000 main frame? This was first introduced by Tek in the 547(BTW, triggers to just over 250 Mhz with a vertical BW spec'ed at 50Mhz) as alternate sweep. This alternate sweep feature in the Tek 547 was done using Gallium Arsenide switching diodes designed in the early 1960's.Ramp volts on top, VCO output on bottom.Tek 7A22 was introduced to the world as the 1A7 plug-in (early 1960's) for the 500 series. The design evolved to become the 1A7A by the mid-1960's. Since that time, the design has been repackaged into everything from AM502, 5A22, ADA400 (CMMR degraded) and...There are similar offerings by Stanford Research Systems (digital controls are shut off to reduce internal digital noise once settings have been made and settled), and Preamble to this day. The trade-off in this design is driven by silicon device physics, physical realities of realizing this design and related. This is just one example of how properly done analog stuff lives on far longer than most progressive minded folks want to or could believe.BerniceQuote from: David Hess on July 02, 2016, 07:39:59 am

author: David Hess
author_rank: Super Contributor
timestamp: July 02, 2016, 08:57:44 am
content: I am only vaguely aware of the origin of the 7A22. It has been discussed over on TekScopes@yahoogroups.com at least once and I went through the schematics back to the 3A9 and 3A10 but stopped before the 1A7.The odd part about delta delayed sweep is that Tektronix continued providing this feature in oscilloscopes after the 7000 series for a short time. The 2247A series of portable analog oscilloscope has it, amazingly enough the 2440 series of DSOs has it, and I think the 2465 series has it as well but I did not really understand it until I got a 7000 mainframe. I do not remember if any of their later old DSOs had it.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: July 02, 2016, 03:52:25 pm
content: Tek 1A7 uses bootstrapping to increase common mode rejection on the front end and a number of other cleaver design tricks to get this performance in the original design. The guy at Tek who designed it is quite cleaver, creative and got it proper. Design excellence endures the test of time. Learn from this.1A7A has a common mode spec of +/- 400 volts at 10uV per division (AC coupled) when used in a 500 series main frame. This is one of the virtues of vacuum tubes. The dynamic range is far and above what modern solid state devices are capable of even approaching. Compare this to modern digital where desirable supply voltages want to be as low as possible to reduce power waste per transition and increase edge transition rates."Slide back" feature of the 7A13 can be found in the modern DSO as DC offset. This is only one of the features of the 7A13, it's real value is as a diff amp with just over 100 Mhz and good common mode at the BNC connectors. A matched pair of Tek P6055 probes were intended for the 7A13 as these probes have adjustable attenuation and HF/LF response to optimize common mode rejection at the probe tip.7A13 has an internal switch allowing the input resistors to be disconnected resulting in theoretical infinite input impedance when the voltage between + and - voltage exactly equals, essentially when the bridge circuit balances (theoretically zero current flow at bridge balance with exactly the same voltage at both half of the bridge) . Similar is found in Fluke differential voltmeters. Origins of the 7A13 goes back to the 1A5 diff plug in (+/- 500 volt common mode range possible) and that plug in has a input specific to the P6046 diff probe. They were developed together as a system. Eventually, Tek introduced the P6046 diff probe with amplifier box as a stand along system. Previous to the 1A5 was the type W plug-in for the 500 series.Delta time, delay sweep display was used for measurements / displays like this.Does this feature have any meaning or value to the modern time domain user, maybe. Most time domain instrument users today have different measurement needs and the way TD instruments are used is not the same, roots of why this never ending grand standing over analog CRT -vs- DSO goes on. They are very different beast for different wilderness.BerniceQuote from: David Hess on July 02, 2016, 08:57:44 am

author: nctnico
author_rank: Super Contributor
timestamp: July 02, 2016, 04:05:58 pm
content: Quote from: Rupunzell on July 02, 2016, 08:20:27 amI don't think anyone is debating or questioning well designed and proven analog solutions for which there is no better alternative today. Earlier this year I bought a Keysight 34461A 6.5 digit DMM. I'm quite sure that the analog section can be traced back to the 1970's or even earlier so from an accuracy point of view getting the latest model doesn't gain you much. The reason I bought the 'new model' and didn't go for a used one is because of the big TFT display, ethernet connection and the ability to create graphs & screendumps on the 34461A.On many DSOs you can use split screen (zoom mode) to see a large part and a smaller section of the same signal which basically is equal to what delayed sweep does and having different time bases. I can show the exact same picture of the pulse and the zoomed in section on my DSO.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: July 02, 2016, 04:50:01 pm
content: There are those who could care less about screen dumps and such...Why are these "discussions" often reduced to a contest or battle of what ever or who ever is the, "winner-victor?"This should NEVER BE about my techno widget is better than your techno widget in my toy box.6 months away from this sand box, same sand box upon return. Kinda sad, really.BerniceQuote from: nctnico on July 02, 2016, 04:05:58 pm

author: nctnico
author_rank: Super Contributor
timestamp: July 02, 2016, 05:06:04 pm
content: Well you keep claiming your old toys are better, can do things newer equipment can't do and are good enough for everyone. In my case having some screendumps from my 34461A in a report made a customer of me very happy and it didn't take any effort from my side. Screendumps matter to me because I make reports with measurements regulary or I just save the screendumps for future reference. It helps a lot to be able to look back at measurement results when a project needs changes or isn't behaving as expected.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: July 02, 2016, 05:32:32 pm
content: Examples and design history are NOT claims of better, they are what they are. If there is a perception older toys are better than new, look in the mirror.Reports and such, do all users of instrumentation require this?Look beyond your world's perspective and points of reference.BerniceQuote from: nctnico on July 02, 2016, 05:06:04 pm

author: David Hess
author_rank: Super Contributor
timestamp: July 02, 2016, 05:51:57 pm
content: Quote from: Rupunzell on July 02, 2016, 03:52:25 pmDSOs can make calibrated measurements directly so slideback measurements are not necessary although they can be more accurate. The offset range of most DSOs is a lot less than a 7A13 so I still find a use for it there.The other place I use slideback measurements is for Gaussian RMS noise both in voltage and time. High end DSOs can handle this just fine in one way or another and do a better job but they are a lot more expensive.QuoteHere again I only traced the 7A13 back as far as the 3A7. This information saved me some time so thank you; I have added the 1A5 and 1A7 to my notes now.Quote from: nctnico on July 02, 2016, 04:05:58 pmBut they have to work within the limits of their single acquisition record which admittedly is not as much of a problem now because record lengths are so much longer although interface performance suffers. With delayed sweep (delayed acquisition?), record lengths can be kept short for higher performance while not sacrificing sampling rate.There is the user interface issue as well. When we tried to duplicate this kind of capability on a Tektronix MSO5000 series which should have been able to do it, it was both difficult and eventually resulted in an unusable state requiring a reset. Magnifying just part of the existing acquisition record worked fine if that was all I wanted to do.

author: nctnico
author_rank: Super Contributor
timestamp: July 02, 2016, 06:11:12 pm
content: Quote from: David Hess on July 02, 2016, 05:51:57 pmWhether or not the UI gets slower depends largely on the oscilloscope's hardware so this is kind of a brand/model specific issue which can be avoided by choosing a different brand/model.QuoteI still don't understand what you where trying to achieve exactly with the Tektronix MSO5000.

author: David Hess
author_rank: Super Contributor
timestamp: July 03, 2016, 04:20:45 am
content: Quote from: nctnico on July 02, 2016, 06:11:12 pmIt came down to displaying two different signals with different timebases and different triggers. I actually wanted to do this with the same signal but it could not do that either or we just could not figure it out.I spent some time looking through various user manuals for currently produced DSOs and is it my imagination or do most of them lack support for trigger after delay? I did not find it for the Tektronix MSO2000, Rigol 1000Z, or Rigol 2000A series. I could not get a manual for the Tektronix MDO3000 or MDO4000 but their discontinued MSO4000 supports it so I am left to conclude that this is now a high end feature.

author: nctnico
author_rank: Super Contributor
timestamp: July 03, 2016, 07:50:21 am
content: My GW Instek GDS2000E series is the only scope I have I know can trigger on different signals with different trigger settings but then again I have not looked for that feature in my other DSOs. The zoom mode (with a split display) can be used for displaying the signals with different timebases.On a DSO the delayed trigger is 'hidden' in the horizontal position control which allows to scroll the trigger position off screen for pre or post trigger.

author: MarkL
author_rank: Unknown
timestamp: July 03, 2016, 03:26:04 pm
content: Quote from: David Hess on July 03, 2016, 04:20:45 amThe Tektronix TDS3000 has an A and B trigger, and you can use it to trigger on A and then display the waveform after a trigger on B. A and B triggers can come from different channels with different slopes and levels. Optionally, you can also set a time delay after A before B is enabled, or delay B triggering by the number of B trigger events.The MSO5000 says it has A/B edge triggering on the datasheet.The Agilent/Keysight DSO/MSO 3000X calls it "Edge then Edge" triggering, but it is the same thing.The old analog Tek 2465 with the CTT option can do all of the above too, and as a bonus can display the A and B triggered sweeps on the screen at the same time (well, really alternating, but it *looks* like it's at the same time).I do not see it on the Rigol 1000Z, but I don't think this is a particularly high-end feature. Your hardware has to have a little extra for the second trigger, so it may not be on the lowest priced scopes.

author: David Hess
author_rank: Super Contributor
timestamp: July 03, 2016, 07:28:31 pm
content: Quote from: MarkL on July 03, 2016, 03:26:04 pmI just took it for granted that low end DSOs which support a delayed sweep (Rigol actually calls it this) would also have a delayed trigger to go with it. They are rare but there are examples of single timebase analog oscilloscopes which have a delay function like the Tektronix 2213 and 2213A. I wonder if Rigol's delayed sweep is actually just scaling the original acquisition.I see now that with their (second? third?) recent website redesign, Tektronix moved the TDS3000 to the end of their list of DSOs; I thought it was discontinued with the MSO2000 or MSO3000 replacing it. I still cannot download their current manuals; their web site is broken again reminding me of the MSO5000 user interface.Almost all of the old analog Tektronix dual delayed timebase oscilloscopes have a B trigger with exceptions like the smaller portables and the T935. Some always use the A trigger source and others are much more flexible allowing a separate B trigger source like your 2465.The reason I was looking for the trigger after delay function on these DSOs is that on oscilloscopes which lack alternate triggering, sometimes the B timebase and B trigger can be used to provide almost the same functionality.

author: Muxr
author_rank: Super Contributor
timestamp: July 10, 2016, 06:21:04 am
content: I enjoy using the analog scopes for the haptic feel and nostalgia the same way I enjoy picking up and operating my old OM-2 Olympus film camera. In absence of a DSO an analog scope can still be quite useful. But a DSO is absolutely the way to go if you're in a market for a new scope.The number of convenient features even the lowest end DSOs have really make a big difference in what you're able to measure quickly.I would take an analog scope over no scope any day.. but if you gotta have only one scope than DSO is the way to go. Some of us are quite addicted to collecting scopes however, and a collection isn't a collection without at least a few analog scopes

author: tggzzz
author_rank: Super Contributor
timestamp: July 10, 2016, 07:40:24 am
content: Quote from: David Hess on July 03, 2016, 07:28:31 pmNot just Tek, of course. Certainly HP had them as well. But then they were aimed at the "high-end" market where you never knew what you would have to do in order to find out what was going on.Lesser (and cheaper) brands were aimed at markets where the range of tasks was well-defined (e.g. TV, audio), and they often didn't even have a delayed timebase.

author: Jwalling
author_rank: Unknown
timestamp: December 12, 2021, 10:56:33 am
content: Quote from: Jwalling on June 30, 2016, 06:28:43 pmI was wrong about the location. It IS possible, though...A fellow named Marco on the Agilent groups.io has figured it out. I'd link directly, but if you aren't a subscriber it won't work.So I'll repost here.QuoteA bit of a PITA to do the mod as you will have to pull the acquisition board.