Should I get an analog scope? - Page 1
Forum section: electronics / testgear

author: mojoe
author_rank: Frequent Contributor
timestamp: January 11, 2015, 02:50:45 am
content: Not too long ago, my analog scope died and I bought a Siglent 100 MHz, dual channel scope. I like the Siglent, but I wonder, is there any reason that I should also have an analog scope? Is there anything in particular that the analog scope would be better for than the digital scope?Joe

author: EEVblog
author_rank: Unknown
timestamp: January 11, 2015, 03:12:10 am
content: Not really. The analog will most likely gather dust.Old analog are a great $50 learning scope for a beginner, but apart from that any modern digital scope is infinitely more useful.

author: vk6zgo
author_rank: Super Contributor
timestamp: January 11, 2015, 03:22:31 am
content: You have a nice Siglent DSO--use it to find the fault in your analog 'scope.You then will have two Oscilloscopes.

author: aviphysics
author_rank: Contributor
timestamp: January 11, 2015, 03:44:30 am
content: I have a working BK Precision 2160 (analog 2 channel 60 Mhz) I have been trying to decide whether or not I want to keep. Before I even got it, I had been spoiled by the nice digital scopes in the college lab, so I have always had a love hate relationship with it (love having a scope, but constantly yearning for a decent DSO).Feels like there ought to be something useful to do with the old scope when the new one arrives, but I can't imagine what. Maybe give it away to a school or something.

author: Lightages
author_rank: Unknown
timestamp: January 11, 2015, 04:04:40 am
content: I have an old 20Mhz dual trace scope, one of the generic ones that were re-labelled many times. It is mainly a wall flower now and I seriously can't think of any use I would have for it over my DS1052E or DS1054Z for anything I do.I think I hold on to it mainly for nostalgia and it isn't easy to get rid of here where I live. It needs a total re-cal.The only reason I can see to get an analog scope is if you have a bare bones budget and don't already have a scope. Maybe another reason is to get a 500MHz scope for a budget price. Otherwise? Nah......

author: tggzzz
author_rank: Super Contributor
timestamp: January 11, 2015, 09:58:49 am
content: Quote from: mojoe on January 11, 2015, 02:50:45 amThe answer is implicit in your question: you haven't found a need for one, so why waste time and space?Having said that,sometimesanalogue scopes are more convenient and don't subtly lie - and in different waysthe same is true for digital scopes. Learn the imperfections of each and every instrument you own

author: tautech
author_rank: Super Contributor
timestamp: January 11, 2015, 10:00:38 am
content: Just asLightagessays, what could you use it for that your Siglent won't do?Maybe a 300 MHz + unit, a good step up in bandwidth from the DSO you have could be worth considering.But if you must, takevk6zgo's advice. Far more satisfaction gained from fixing your broken one than buying another.There is plenty of help available here for a repair on it.Start a new thread in The Repair board, have a look for the Service manual in the links in the Repair board......there's your new project.And when it's fixed and the yearning for an Analogue scope has been satisfied, sell it and DONT look back.

author: Howardlong
author_rank: Super Contributor
timestamp: January 11, 2015, 10:45:38 am
content: Maybe I'm too much of an old fart, but I find I use analogue scopes at least as much as digital ones.I regretted selling a 2465B some years ago, I sold it as I could do everything I needed on the digital scope I had. A couple of months ago I bought a 2467B and I find it gets used every day. It's the immediacy when setting the adjustments that I really like. But there's nothing it does that I couldn't do with the Agilent DSO sitting next to it.Of course, you could always forget about building and designing electronics, and just make a huge oscilloscope collection instead, I think there are a few of us on here who are like that. Four months ago I owned one scope, I now have eight. I blame EEVBlog, thanks Dave.

author: artag
author_rank: Super Contributor
timestamp: January 11, 2015, 01:36:58 pm
content: Quote from: EEVblog on January 11, 2015, 03:12:10 amThat depends a lot on the scopes, imho.Some of the advanced digital scopes Dave has been testing make a pretty good job of it, but at a price. I had a Rigol 1052E for a while and it stayed under the bench for most of the time, getting brought out for portable jobs and the occasional thing that actually needs storage. I'd always prefer an old Tek465.This is hardly surprising - the Tek cost $n000 in it's day and is still a delight to use. Furthermore, you can pick them up for less than a new cheap chinese scope.I've upgraded to an Agilent 7000 and now do use the digital for all its great features, more often than the analog. But it's not perfect - it still has too many menus, and lacks the interactive feel of the analog scope : it's using an awful lot of expensive hardware to try to emulate that.

author: Howardlong
author_rank: Super Contributor
timestamp: January 11, 2015, 01:45:34 pm
content: Quote from: artag on January 11, 2015, 01:36:58 pmAgreed, an example is setting up XY mode on a DSO. It took me quite some time to get the right settings on the DSOs I have here, and they're all a bit different. You need to be mindful of display and acquisition settings including memory depth and persistence, whether to draw lines or dots, whether to have sin(x)/x on or not. Some of the DSOs need to be triggered, which makes no sense in XY mode. In contrast, all the analogue scopes were setup in less than five seconds.

author: G0HZU
author_rank: Super Contributor
timestamp: January 11, 2015, 02:00:23 pm
content: There's no 'one size fits all' answer to this but in my case I still have a Tek 465 analogue scope here because my main interest is RF/analogue.I also have a DSO and I swap between them depending on what waveforms I want to look at. DSOs tend to become hard work to set up when trying to display certain complex waveforms although they seem to get better with each passing year as new models of DSO are released.Maybe one day I'll find/buy a better DSO that means that my old Tek 465 will only be used part time and will spend a lot of time on a storage shelf but for now it still commands a permanent position on my workbench.However, I would suggest that the vast majority of EEs stopped using analogue scopes many years ago.

author: egonotto
author_rank: Super Contributor
timestamp: January 11, 2015, 02:18:51 pm
content: Hi,if you show the curves from an transistor-curve-tracer on an scope than an analog scope is far better than most DSOBest regardsegonotto

author: torr032
author_rank: Regular Contributor
timestamp: January 11, 2015, 02:29:10 pm
content: Quote from: aviphysics on January 11, 2015, 03:44:30 amIf you don't know what to do with it then give it to me pleaseI would be more than happy to own a scope like that. Scope prices are very high in my country and I can't afford to buy one.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 11, 2015, 03:08:59 pm
content: Quote from: mojoe on January 11, 2015, 02:50:45 amTo the question "Is there anything in particular that the analog scope would be better for than the digital scope?", the answer is simple: Those analog ones are still unsurpassed with regard to intensity grading. DSO's today have still hard times (and have hard to work) to emulate that and often lie with that. Especially with analogue work the intensity grading holds a lot of useful information. DSO's are basically storage scopes that come in handy for digital work. Most of the extra features of DSO's are tailored to digital work and have more complex UI's.It depends largely on your needs. If it is just analogue work, well a good second hand analog one will do and spares you the hassle of digging through useless features, just to recognise you don't need them. If it's mainly digital work, almost any DSO will do, select one for your needs and budget. If you do both you are going to the higher level (and more expensive) DSO's with reasonable intensity emulation and large update rates.It's funny that all the DSO makers work hard today to make the image as much analog like as in the old days. Something to think aboutI myself use the Rigol DS2102 for more than a year now as an all-rounder for my private own use. Its intensity grading is far away from a pure analog one but I can live with it. For digital (micro controller and programmable logic) work it is far more convenient and productive than my old TEK465B. But for adjusting my turntable with a test record my TEK may shine

author: aviphysics
author_rank: Contributor
timestamp: January 11, 2015, 08:21:35 pm
content: Quote from: Pjotr on January 11, 2015, 03:08:59 pmDSO's also have advantages in analyzing intermittent analog signals, like the ouypu of particle detectors. I think you would probably need to build some kind of analog delay to get a good look at some of the signals I deal with an anolog scope (largely cause the energy analyzer doesn't output a trigger until the peek is gone.) You would also need a scope with a good persistance option or a camera setup to look at single shot events.

author: KedasProbe
author_rank: Frequent Contributor
timestamp: January 12, 2015, 10:54:06 am
content: I did buy an analog (not new) after having a DSO.My reasons were:- Higher bandwidth and update rate for lower price (an AM signal looks right compared to my DSO Hameg)- Having a second opinion, not having to believe the digital version.- And I admit some nostalgia, feeling closer to the electronics than with a digital processed signal.Having said that, if I can only keep one I would keep my DSO.

author: pedroteck
author_rank: Contributor
timestamp: January 12, 2015, 12:50:02 pm
content: Whats great about analog scopes is that they can be easily fixed , also the CRT screen is very durable .

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 12, 2015, 03:22:40 pm
content: A big difference is also, analog scopes display signals real time, DSO's do not or semi real time. This comes in when looking for infrequent signals like glitches and noise spikes.When a DSO samples a signal. the signal is stored in fast memory. Data from that memory needs to be processed and transferred to video memory (or display memory you may call it). That takes time and during that time de scope is "blind" for incoming signals for say more than 90% of the time. The chance to capture a random event in time is low by that. With analog scopes the signal is send directly to the vertical deflection plates. The horizontal time axis is a simple sawtooth waveform. Retrace can be very fast, much less than 10% of the total time, leaving near all the time to trigger and capture the waveform. So chances are much higher to see an infrequent signal.A solution to this with DSO's is to use a large segmented fast memory and record a long time period continuous to it without processing it (not displaying it). A nice example how this works is given in this video:(from app. 18 min). This only works when the scope has proper tools to detect, find and lookup an infrequent event in a huge memory. Without it, a large memory for recording signals is almost useless. An example of how this can turn out is demonstrated in this video:(from about 35 min. on).

author: nctnico
author_rank: Super Contributor
timestamp: January 12, 2015, 04:54:15 pm
content: Quote from: Pjotr on January 12, 2015, 03:22:40 pmDSOs worked that way 25 years ago or so. The higher end ones have had high waveform update rates since then. Besides that analog scopes (especially the ones with on screen cursors and so on) have a large dead time as well.

author: c4757p
author_rank: Super Contributor
timestamp: January 12, 2015, 04:56:42 pm
content: Quote from: nctnico on January 12, 2015, 04:54:15 pmYep. Many analog scopes have a dreadfully low trace duty cycle. It makes sense - they're not exactly meant for capturing single events.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 12, 2015, 05:25:04 pm
content: It is not exactly the update rate by itself but the chance for the scope get to trigger properly on infrequent signals.Although high update rates are claimed in the order of 50K to 200K for DSO's, in reality you get most of the time much less dependant on memory length in use at the moment. And you need a lot of samples to get a reasonable intensity grading.I am not pushing anolog in favor of DSO, but there is much more under the hood people are not aware of. With a DSO the risk ofnotseeing what you looking at is simply higher. You need to be more aware of what the thing is actually doing.And we are not talking about high end DSO in specialMost of the debate is more about the affordable entry level ones. Many make a mess of modulated signals.

author: Andy2
author_rank: Contributor
timestamp: January 12, 2015, 07:23:57 pm
content: There are a few things that analogue scopes do that even expensive DSO's struggle with. A while back I got myself a DSO (200 MHz b/w, 1Gs/s) and it was great for audio and digital stuff and capturing slow stuff was a breeze, but it just refused to display a sensible rendition of an amplitude modulated carrier wave. IIRC it was passable up to about 10 or 20 MHz, but above that it collapsed into a tangled mess of aliasing and rubbish. We had a long thread on this a while ago......

author: tautech
author_rank: Super Contributor
timestamp: January 12, 2015, 07:31:38 pm
content: Quote from: Pjotr on January 12, 2015, 05:25:04 pmYou shoud be.You've obviously used both to come to this level of understanding.But RTFMThe one area were DSO's excell is their Trigger suite. Even entry level.Proper informed use of the triggers available leaves Analogue CRO's in the dust.

author: wreeve
author_rank: Unknown
timestamp: January 12, 2015, 07:57:08 pm
content: I've just bought an analogue 'scope to allow debugging of old Atari vector arcade games; many analogue 'scopes have a Z input which is needed as a blanking input for displaying XY vector plots! £10,000 infiniium isn't much use for this!

author: tautech
author_rank: Super Contributor
timestamp: January 12, 2015, 08:10:17 pm
content: Quote from: pedroteck on January 12, 2015, 12:50:02 pmThat's a reasonable statement, but as in all equipment some areas are under higher stress than others.PSU's for example, but a CRO also has HV supplies that are well known to be troublesome on some scopes. There is also the Plate output amps that often are swinging signals in the 150 V range. These fail too.DSO's by comparison have little that operates at any high voltage, only the backlight for the LCD display.While they may be more complex in the signal path, the frequency of failures is extremely low.I've had a good few CRO's and had to repair all of them at some time.Some of the HV transistors and other HV componentry is getting harder to find now and this is a good incentive to move to more reliable DSO's IMO.

author: Pjotr
author_rank: Frequent Contributor
timestamp: January 12, 2015, 08:33:24 pm
content: Quote from: tautech on January 12, 2015, 07:31:38 pm:grinn:Oscilloscopes are industrial tools (not intended to be home toys) where productivity is first place. If the industry demands analog oscilloscopes because of unsurpassed productivity, they didn't fade away from the market. Most of the average DSO's can do 95% of the work needed. The other 5% is dedicated/special area.

author: tautech
author_rank: Super Contributor
timestamp: January 12, 2015, 08:54:12 pm
content: Quote from: Pjotr on January 12, 2015, 08:33:24 pmExactly.And you won't see any CRO's mentioned as suitable in this thread:https://www.eevblog.com/forum/testgear/professional-scope-purchasing-criteria/

author: Howardlong
author_rank: Super Contributor
timestamp: January 12, 2015, 11:44:36 pm
content: So here's a thing. Doing my usual pottering today, I just finished an hour or so ago, started reading this thread again, and the only two scopes that went on today were an HP 1980B and a Tek 2467B. I was debugging and testing some firmware in a board I made up based on Microchip's PIC32MZ series, a 200MHz MCU, to do with PWM, but some of the speeds were up to 100MHz getting the clocking right.It never even occurred to me to turn on the DSOs sitting adjacent. Yes, they'd do the job too, but the ease of twidlin' them knobs on a CRO, seeing the immediate response, and dealing with it right there and then, is like nothing else.Choose the best -available- tool for the job.

author: Howardlong
author_rank: Super Contributor
timestamp: January 12, 2015, 11:52:48 pm
content: Quote from: wreeve on January 12, 2015, 07:57:08 pmHere's my Asteroids on a PIC I hacked together a few days ago. The Infiniium is at 00:00:54. It took me at least ten minutes to set up XY reasonably. Among other things, that SOB requires a trigger to work in XY mode, which is nonsense.http://youtu.be/BXOHyjeLAXM

author: tggzzz
author_rank: Super Contributor
timestamp: January 13, 2015, 12:30:38 am
content: Quote from: Howardlong on January 12, 2015, 11:52:48 pmSome HP scopes have asteriods as an Easter Egg. But I'm sure you knew that!

author: Howardlong
author_rank: Super Contributor
timestamp: January 13, 2015, 12:40:34 am
content: Strangely enough, it was the HP scope that had asteroids that led me to buying the Infiniium, via a rather circuitous and possibly over-analysing way!

author: monksod
author_rank: Contributor
timestamp: January 13, 2015, 03:52:34 pm
content: Quote from: EEVblog on January 11, 2015, 03:12:10 amWhere do you find these "$50" scopes? I keep my eye on eBay/gumtree etc but never seem to find anything at that price, apart from "non-working/sold for parts" etc...

author: c4757p
author_rank: Super Contributor
timestamp: January 13, 2015, 03:57:14 pm
content: Quote from: monksod on January 13, 2015, 03:52:34 pmPatience! I get 'em for $25ish broken, and see them regularly for $50ish in good shape.Keep in mind people will often sell them as "for parts" or some other label that doesn'tactuallyclaim it's broken to avoid having being held responsible for makingsureit works.

author: PaulAm
author_rank: Frequent Contributor
timestamp: January 13, 2015, 11:02:13 pm
content: I've bought a lot of test equipment listed "for parts or repair" that actually worked just fine or only needed minor repair. If they're completely dead, it's often a power supply issue.It is something of a gamble though. The odds aren't bad though; I've only been skunked a couple of times. I also like fixing 70s-80s era equipment, which doesn't hurt.Since you're in the US, keep an eye on craigslist for cities within driving distance. I picked up a Tek 7603 for $10 that way (that was was broken, but I wanted it for parts anyway). I did pick up a working Tek 422 for $35 once. You need to be patient though; it may take a while for one to show up.Also, check on available documentation. You don't want to end up spending more on a manual than you spent on the scope.