My first oscilloscope - Page 1
Forum section: electronics / testgear

author: mike_mike
author_rank: Super Contributor
timestamp: April 01, 2015, 05:22:12 pm
content: Hello. My name is Mike. I am new to this forum.I want to buy a oscilloscope for my electronics laboratory.I don't want to spend a lot of money because my budget is very limited.I am looking at Atten AT7016. It is about 150 euros. Worth to buy it ?Please tell me if you have any experience with this oscilloscope ?I want to use the oscilloscope to measure the ripple at the output of a linear power supply.

author: tggzzz
author_rank: Super Contributor
timestamp: April 01, 2015, 05:34:39 pm
content: Quote from: mike_mike on April 01, 2015, 05:22:12 pmThere are many many threads on exactly this topic on this forum, and some are currently active.A little research on your part will enable you to formulate questions that will be of direct use to you. Without that you will get standard generic replies.

author: tautech
author_rank: Super Contributor
timestamp: April 01, 2015, 07:41:39 pm
content: Welcome to the forum.Please place your country flag in your profile for local recommendations.DON'T BUY IT.It is a CRO and has very limited features for the money.If you MUST have a CRO get a SH Tek, Phillips, Hameg, HP etc.Don't buy SH unless you can source Operation and Service manuals.Everybody these days are getting DSO's for the mass of features they offer.How large is your budget?

author: pickle9000
author_rank: Super Contributor
timestamp: April 01, 2015, 07:46:52 pm
content: Not worth the money.

author: ebastler
author_rank: Super Contributor
timestamp: April 01, 2015, 08:13:25 pm
content: Quote from: tautech on April 01, 2015, 07:41:39 pmI fully second what tautech has written. Since you may be relatively new to this, and potentially a non-native speaker, I thought I'd add a little glossary: ;-)CRO = cathode ray oscilloscope (old style, analog cathoda ray tube - cannot store and display traces of rare events)DSO = digital storage oscilloscope (digitizes and sores data, display on an LCD display)SH = second-handIf our budget is below 300 Euro, a decent second-hand CRO is a good recommendation. You should actually be able to get entry-level models from the good brands tautech has recmmended starting at 100 Euros. If you can afford 300 Euros or a tad more, a DSO offers many additional possibilities. The Rigol DS1054Z currently sells at 299 Euro + tax, and is amazing value. (4 channels, upgradeable to 100 MHz bandwidth, many measurement and trigger options.)

author: Muxr
author_rank: Super Contributor
timestamp: April 02, 2015, 06:47:55 am
content: Yup. If you can stretch your budget to get a DS1054Z, that's what you should get, as it's the best bang for your buck.If not get a sub 100 euro used analog scope.Not familiar with it personally but Siglent's SDS1052DL is just above your budget and I think it would be ok as well.

author: pickle9000
author_rank: Super Contributor
timestamp: April 02, 2015, 07:08:57 am
content: If you can only get one scope a dso will do you well. I have a basic Siglent dso and it was worth every penny. I have other scopes I use daily but I use that one in the field. Even if you get another scope in the future it will still have value in the shop.I have one of the Rigols as well and 1054z is just killing everything close to it's price point. I have more expensive scopes but it's a good everyday scope no question.

author: miguelvp
author_rank: Super Contributor
timestamp: April 02, 2015, 09:43:20 am
content: +1 on modern DSOs, here is a pictorial example:vs:On the analog one, you have to do math to figure out things and you only get OK approximations.Signal using the x10 magnification in the time base module, so it's 5ns per division.A 26MHz clock has a period of ~38.46154 ns divided by 5ns that will give me ~7.7 divisions.Probe is x10 so voltage per division is 10 times larger.Edit: working it backwards as you would if you didn't know the source signal is.5ns x ~7.7 divisions = ~38.5 ns38.5ns / 1000 (us/ns) / 1000 (ms/us) / 1000 (s/ms) = 0.0000000385 secondsFrequency is the inverse so 1/0.0000000385 = 25974025.974025974025974025974026rounding off: 25974026 Hz or 25.974026MHzError: 25974 cycles per second (Hz). (On a well calibrated scope but you have to rely on your uncalibrated eyes and the lack of divisions that you wouldn't even see if they could display it on the analog scope)Digital ones just tell you what is what. no fuzzing aroundPlus you get more data showing you where noise or ringing is at (both measurements made with the same probe and with a spring ground as close to the OCXO as posible).Edit: Rigol is not a DS1054z, it's a DS2302 (300 MHz) but the same measurements are available I think on the DS1054z.Analog is a Tektronix 7613 (100 MHz) and the signal is magnified with the x10 zoom function with time setting at 50ns. Also I had to calibrate the tek by adjusting pots inside the scope, had to do nothing to the Rigol.Edit2: Don't get me wrong, I love the retro look of the Analog scopesEdit3: Note that I had to square the signal on the analog scope to actually make the measurements, on the digital one I didn't even bother that much, it takes more preparation on the analog one to actually measure what the signal is showing you.And this doesn't even touch the milliard other features the digital scopes bring to the table.

author: tggzzz
author_rank: Super Contributor
timestamp: April 02, 2015, 10:46:35 am
content: Quote from: miguelvp on April 02, 2015, 09:43:20 amOh dear. If only that was true.All instruments lie, albeit in different ways.Digital scopes do have significant advantages, but quite frankly if you can't interpret a unannotated graph (i.e. and analogue trace) then you should seek employment elsewhere. Maybe as a software "engineer" (and I use that term loosely). In addition, analogue scopes do have significant advantages in some situations, but this isn't the place to rehash that argument.There is a good argument that analogue scopes are easier for an beginner to understand becauseallthecontrolsand optional settings are directly visible on the front panel. I've seen too many beginners that are unable to use a digital scope because they didn't realise they needed to tweak the setting buried on the fourth menu of the fifth page.

author: miguelvp
author_rank: Super Contributor
timestamp: April 02, 2015, 10:52:39 am
content: True they lie, but they are more accurate for all purposes.As for usage, analog scopes have a lot of voodoo in them, digital ones are very simple to use in comparison for the same task.Ask any of these new guys that never used an analog one what the cal setting in most of the knobs do, they will be clueless.And how to set the delay or use the x-y. They will get bored by page 10 of the manual and they don't even need to read the manual for the digital ones (even if they should based on some of the questions they ask).

author: miguelvp
author_rank: Super Contributor
timestamp: April 02, 2015, 10:59:26 am
content: But let's not confuse one thing, all scopes have analog front ends and some modern DSOs have sub-par analog parts.But all being the same, DSOs can interpret the analog front end better than human eyes and they make the measuring tasks easier.case in point:Look at this signal:and come up with the actual frequencyAnd try the same thing with a 100MHz DSO like the DS1104z Rigol, who is going to be closer?And that's just one quarter of the scope's "stated" capabilities.

author: tggzzz
author_rank: Super Contributor
timestamp: April 02, 2015, 11:05:25 am
content: Quote from: miguelvp on April 02, 2015, 10:52:39 amNo: "all" is an inappropriately strong word in this context. People have given many examples of that, and I'm not going to rehash them here.QuoteThat entirely depends on the task.QuoteSo what?QuoteHaving taught people to use both, I've repeatedly observed that they learn faster and better if they start with an analogue scope. Once they are familiar with analogue scopes, they can make good use of the facilities a digital scope provides, and not fall into some of their traps.

author: tggzzz
author_rank: Super Contributor
timestamp: April 02, 2015, 11:17:48 am
content: Quote from: miguelvp on April 02, 2015, 10:59:26 amYes indeed. A 1GS/s scope should, of course, be able to see a 500MHz signal! And there's no way that a 40MS/s scope can see a 1ns edge, is there! How many times have I heard those misapprehensionsQuoteRubbish.Your statement is true for many common cases with well-behaved signals.But not in all circumstances. I've seen good scopes from reliable manufacturers beextremelymisleading unless you realise that it is necessary to tweakthatburied setting.One case that springs to mind was a "show me the analogue eye diagram" of a PRBS signal. The analogue scope instantly gave the correct answer. The digital scope gave aridiculouslywide envelope, unless you knew that youhadto change how it postprocessed anddisplayedthe captured signal. And at that point is showed the same display as the analogue scope.Many experienced analogue/rf engineers prefer to use an analogue scope when first looking at a signal. After they are convinced that "nothing funny is going on", they switch to a digital scope for detailed measurements. The school of hard knocks has taught them to do that.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 02, 2015, 11:26:32 am
content: Quote from: tggzzz on April 02, 2015, 11:05:25 amI heard that often, but quite frankly based on the large number of apprentices we (where I work) teach I'd say that is wishful thinking. We don't teach them on analog scopes for roughly a decade now, simply because it offers no benefit, and in contrast often caused more confusion than necessary. Most entry level scopes are also dead easy to operate, and students can learn all basics on digital scopes as well, and often even much better, aside from avoiding learning outdated practices that may have been useful in the old days but often are actually counterproductive on modern scopes.We still discuss analog scopes briefly and explain how they work, but the focus is on tools for this day and age and not for something from the past which has long been obsolete.I myself did learn on analog scopes during my school days, but was introduced to digital scopes early on. And quite frankly, knowing analog scopes really didn't help me in understanding and working with digital scopes.

author: tggzzz
author_rank: Super Contributor
timestamp: April 02, 2015, 11:39:50 am
content: Quote from: Wuerstchenhund on April 02, 2015, 11:26:32 amI think that is fair comment, except that it isn't "wishful thinking" on my part - it is merely what I've observed.However I do object to two points thatyouweren't making:that a beginner should avoid a cheap and available scope merely because it is analoguethat digital scopes arealwaysbetter

author: miguelvp
author_rank: Super Contributor
timestamp: April 02, 2015, 11:47:11 am
content: Quote from: tggzzz on April 02, 2015, 11:17:48 amYou probably mean, many experienced analogue/rf engineers expirience with the first generations digital scopes, right?I would not thing you are referring to the last ten years.But if it's something that has happened recently please do tell and link some info about it because it will make a very interesting read.Maybe you are right and they use just analog only tech to capture a trillion frames per second being able to capture light traveling.One thing is true, the world is analog but right now we must rely in the digital domain to make use of that analog information until someone comes along with an more efficient analog only counterpart.There must be a way to compensate for the unwanted noise.And yes, a digital scope with the same analog front end is better than a analog only scope, there is no doubt about that.

author: franksanderdo
author_rank: Contributor
timestamp: April 02, 2015, 02:46:49 pm
content: hmmmm.....I am not yet sure that the (starting) argument will help mike_mike in his decision process.Knowing that all of you are much more experienced than I am, maybe you can help me out:Is it possible to build a kind of budget table which would give a hint for mike_mike?Something like:<= 50USD no chance, forget all the crap<= 200USD some second hand CROs or some entry DSO (Hantek???) with the a/b/c limitations<= 500USD entry level DSO i.e. DS1054 ...maybe this approach can help newbies as a starting point and then they have to investigate further?All the BestFrank

author: Michaela Joy
author_rank: Contributor
timestamp: April 02, 2015, 03:29:59 pm
content: @mike_mike: IMHO, buying an oscilloscope is like buying a car.You want it to be adequate for your immediate needs, and you don't want to outgrow it too quickly. If you buy a new scope, you get a warrantee. If you buy a used scope, you don't know what the previous owners did to it, and you don't know how long it will last before it needs to be repaired. If you buy an older scope, you may not be able to fix it, or the cost of repair may very well be too high to justify the purchase.As far as analog vs. digital scopes, each has it's place in the lab. If I could, I'd buy one of each. The ability to capture a sporadic event can be -very- handy.But good digital scopes are not cheap. Neither are good analog scopes.What area are you looking to work in? Digital? RF? Audio stuff? Do you need to see signals above 100mhz? The answers to these questions will help you decide what to buy.Also, try to learn as much as you can about oscilloscopes, How to use them, and what their limitations are.IIRC, there is an oscilloscope video posted here. Find it, watch it, and learn as much as you can from it.Only then can you make an intelligent decision as to what's best for your lab.:MJ

author: Fungus
author_rank: Super Contributor
timestamp: April 02, 2015, 03:48:10 pm
content: Quote from: franksanderdo on April 02, 2015, 02:46:49 pmThere's not much point IMHO.If we draw a graph with price vs. value for money there will be such a HUGE hump where the DS1054Z goes that you'd be silly to buy anything within $200 either side of it.That pretty much rules outanythingcheaper than the DS1054Z as being "good value for money" and you pretty much have to go up to something with 2Gs/sec to get anything better.Maybe if you can get an analogue scope for under $100 then it will keep you going while you save up for your DS1054Z, but, otherwise... keep saving up!A good bet is to find local electronic clubs, etc., and talk to people. Many of them have dozens of old analogue CRO scopes piled in their garage and would be happy to let you have one if you can convince them you're a good home.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 02, 2015, 03:48:28 pm
content: Quote from: tggzzz on April 02, 2015, 11:05:25 amFair enough, and I'm sure that learning on analog scopes was actually a benefit when digital scopes were still in its early days and analog scopes were still the dominant type of scope. But that hasn't been the case any more for a very long time.QuoteI didn't, because a beginner (especially if he/she wants to grow in EE) is generally better served with a modern entry level DSO than with an analog scope.Of course, if it's really cheap (i.e. <$100) and someone wants it for curiosity/interest then get an analog scope, why not. It can still be fun! But as a "learner's scope" it's no longer ideal as it doesn't teach techniques and appreciation for modern day scopes, which is what they*will*have to work with eventually.Even if someone is severely cash-strapped I'd recommend to rather save a bit longer and get a DSO than sinking $100 or so in what essentially is a museum piece with very limited use.QuoteWell, I'm sure one could construct a situation where an analog scope would still be better (i.e. something where beam intensity modulation aka Z input is required, something that is usually absent from digital scopes, although I'm sure that these days there are other alternatives for such tasks), but the reality is that there is essentially*zero*demand for new analog scopes for over a decade, and for that reason no-one makes them anymore. It's a simple fact. And it hasn't resulted in professional labs hording analog scopes, or prices for analog scopes skyrocketting, again simply because it's a obsolete tool that no-one really wants to use anymore.And frankly, considering what good digital scopes can do, this is hardly surprising. You really get a lot more information from a good DSO than even the best of the best analog scopes can give you. And it's not that the analog scope isn't occasionally lying to you, because it is. Users are often lured into a perceived "precision" that isn't there and merely exists in their minds.QuoteWell, I would say that either these RF engineers work in a very poorly equipped lab which only has some crap or antique DSOs, or they simply don't know how to use a DSO properly, which quite often is because people transfer things and practices learnt from analog scopes to digital ones without real appreciation of how a DSO works and what techniques are actually appropriate.

author: Fungus
author_rank: Super Contributor
timestamp: April 02, 2015, 03:56:37 pm
content: Quote from: Wuerstchenhund on April 02, 2015, 03:48:28 pmFarnell lists 10 of them, from various manufacturers:http://es.farnell.com/webapp/wcs/stores/servlet/Search?st=osciloscopio&catalogId=15001&categoryId=700000027004&langId=-5&storeId=101761150€ for a 2-channel, 20MHz 'scope??http://es.farnell.com/gw-instek/gos-622g/oscilloscope-bench-2ch-20mhz/dp/2450060

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 02, 2015, 06:56:41 pm
content: Quote from: Fungus on April 02, 2015, 03:56:37 pmThat looks more like old stock (and Farnell probably would rather keep it indefinitely at list price than selling it off very cheaply). As far as I know R&S (Hameg) has ceased analog scope production a while ago (IIRC the HM400 was their last one, mostly made for "emerging markets"), and I'd be surprised if the others are still in production (i.e. the Digimess is from 2003).I guess they are still marketing the remaining units instead of throwing them away but I seriously doubt that there are still factories pushing out those things.And it's not that any of the scopes listed are even good analog scopes, they all seem to be made to lowest costs, with mostly pretty poor specs. Unless it's really for some crude task where a digital scope is definitely not an option (if such thing even exists), anyone who seriously considers buying one of those needs his head examined.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 03, 2015, 06:09:21 am
content: Something to consider about CRT analog scopes -vs- DSO. This was written by Paul Rako at EDN. There are very good reasons why more than a few veteran engineers seasoned by decades of real world stuff still like analog CRT scopes and will use a DSO when the need is there. The both have their place in the world of T & M.http://www.rako.com/Articles/43.htmlThis was published not too long ago in EDN.http://www.edn.com/design/test-and-measurement/4389436/Readers-speak-out-about-their-favorite-instruments"Reader BobL also prefers analog oscilloscopes. He’s managed to keep two Tektronix 7904 analog oscilloscopes running in his lab. “Transients are sometimes impossible to see with a digital scope, but analog display is great.” An engineer using the name Opcom also has two Tektronix 7904s. “Lets face it,” Opcom wrote, “digital ones update sloppily and nothing is as good looking as an electrostatic deflection CRT. Digital scopes are useful for many things but the trace on a CRT can be interpreted in more ways than the digitized LCD image.”Based on the comments, I conclude that there is a whole group of engineers who still prefer analog oscilloscopes no matter how much digital oscilloscopes have advanced. Dave McGuire even had a message for the oscilloscope makers when he wrote that his favorites are “My Tek 2465A and 7904A oscilloscopes. Yes I have some fancy digitizing scopes (the Tek 222 is very handy on the road!) but nothing beats an analog scope for fast transients...analog and digital scopes are completely different instruments. Are you listening, Tektronix and Agilent?”Keep in mind, these comments are from folks who are working engineers at large corporations who can afford and has the most current test toys, yet more than a few are still using their decades old Tek & hp stuff.Bernice

author: smjcuk
author_rank: Frequent Contributor
timestamp: April 03, 2015, 07:47:53 am
content: Not a fan of new digital scopes. Four reasons I won't buy one as an amateur:1. Reliability. Check eBay. Every cheaper second hand one I've seen has dead channels/amps. Doesn't matter if its Rigol or LeCroy or anything inbetween. This leads on to...2. Complexity. The things are basically a small analogue front end, an FPGA and a computer. Also its all SMD devices and difficult to repair. Channel gone? Good luck fixing it out of warranty without a rework station and an expensive Farnell order (if you can actually get the parts in that small volume). Maybe aliexpress has the part: 29 day lead time...3. Crippleware. The hardware of the cheap stuff is capable but to tier the devices so you can pay for what you need and they can sell a small selection of base hardware configs, so you have software licenses to deal with. Or in the case of Tek, expensive feature modules that don't do anything other than switch a feature on. I think Rigol do this with license keys. Buy a Ferrari, find its limited to 60mph, then spend another $6000 on the 1000mph upgrade? Nope - no thanks.4. Trust. The first thing my electronics lecturer said to us at university was that "all equipment tells fibs and lies". To have vast swathes of information presented to you relies on certain algorithmic and mathematical assumptions which aren't really well documented. Coming from a professional software/math background this is a surprisingly complex and error prone area. There are as many rules as your average analogue scope there to consider. To package this up in something entirely trustworthy isn't possible. Perhaps 90% accurate but that's short enough not to want to make any assumptions about. A fine example is determining the frequency of a complex wave isn't as straightforward as it makes it out to be, even with an FFT in front of it and a tick on the feature list.If I was doing it professionally I would buy a new DSO. Then write it off as operating expense when it dies but as an amateur the investment is a bit of a problem.

author: tggzzz
author_rank: Super Contributor
timestamp: April 03, 2015, 08:51:28 am
content: Quote from: Rupunzell on April 03, 2015, 06:09:21 amThose are sensible, balanced points and articles - since they notebothtypes have advantages and disadvantages.Anybody that claims one is "better" that the othermusteither statewhenit is better, or be thought to be ignorant and/or unreasoning.

author: tggzzz
author_rank: Super Contributor
timestamp: April 03, 2015, 08:54:14 am
content: Quote from: smjcuk on April 03, 2015, 07:47:53 amOh, that's so true! It is all to easy to be burned by internal hidden algorithmic assumptions and short-cuts that only work with nice well-defined simple "theoretical" signals.

author: tggzzz
author_rank: Super Contributor
timestamp: April 03, 2015, 09:07:54 am
content: A rather nice summary from a professional technical writer:Quotefromhttp://www.rako.com/Articles/8.html

author: ebastler
author_rank: Super Contributor
timestamp: April 03, 2015, 10:00:09 am
content: Quote from: tggzzz on April 03, 2015, 09:07:54 amU.S. based writer?On a slightly more serious note -- we seem to have lost the original poster in this passionate discussion of CRO vs. DSO?

author: tggzzz
author_rank: Super Contributor
timestamp: April 03, 2015, 10:09:33 am
content: Quote from: ebastler on April 03, 2015, 10:00:09 amOh, yes, what a surprise!QuoteOh, yes, what a surprise!

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 03, 2015, 10:57:21 am
content: Quote from: Rupunzell on April 03, 2015, 06:09:21 amOk, lets have a closer look what the author is saying:"My everlasting desire to use analog scopes is driven by two factors:1) Analog scopes rarely lie.2) The decent user interface of analog scopes.The first point is well understood..."Obviously not by the author, because analog scopes *do* lie, just in a different way than digital scopes (i.e. they hide information). Which seems to be widely ignored by analog scope users, as there seems to be a common belief that the analog scope is more "honest". Which simply isn't true.But at the end of the day all test instruments lie, which is why it's important that an engineer knows his instruments, what they do, how they are used properly, and where its limitations are.The author then goes on:"...Digital scopes alias and display artifacts that have nothing to do with what is really going on. All a digital scope does is take a sample periodically and store it into memory. You have to understand that some software geek has decided how to "connect the dots" between samples. What it displays may have nothing to do with what it is connected to."Artifacts and aliasing are mostly a sign of not knowing the specific's scope's limitation or how to use a DSO properly (which brings me back to my original point of applying analog scopes knowledge and techniques often isn't appropriate for using with digital scopes), and the author is clearly oblivious to the fact that it's not "some software geek" (note the derogatory undertone!) decides how dots are connected but simple basic maths which is parts of the fundamental knowledge about signal formation.But lets move on:"... Last week I had to take some picosecond rise-time measurements. A tech rolled up the Tek 11801B digital sampling scope. He gave a clearly sadistic grin and said "you should have a lot of fun with this". I soon understood what he meant. This scope is essentially unusable from the front panel.[..] "For those that don't know, the Tek 11801B is a modular sampling oscilloscope from roughly around 1992, so even at the time he wrote that article (2001) the scope was already roughly 19 years old!Also, the 11801B is a high bandwidth scope that was mostly meant for TDR measurements and which was never designed as a general purpose scope, a fact to which the author obviously was downright oblivious:Now the tech made excuses, saying the scope was really set up to do TDR (Time Domain Reflectometry) measurements and that it was intended to be run from GBIB, not the front panel. I still consider the interface to be not only bad, but downright evil.So one argument of the author why he prefers analog scopes in 2011 is that the 19 year old special purpose samling DSO made in 1992 which he clearly didn't understand had a terrible user interface? Seriously?There's more:"But don't think that you can't get the exact same information from a 20-year-old scope you got at a flea market for 50 bucks. This week I am putting huge current pulses into some transistors to observe the second-area breakdown effects. [..] Another factor in my use of the digital scope was that I wanted to send the data in an email. This particular scope had a floppy disk in it so it was easy to save the file as a TIFF standard file. Then I could use Photoshop to convert it to a GIF file so that I could send it attached to an email in a format any web browser and most email packages can display. "So the author again is talking about a scope that even when he wrote the article in 2001 was already 8 to >15 <ears old! The image also clearly shows the screen of a very old DSO using a mono CRT (maybe a Tek TDS3xx).And last but not least:"We are soon going to buy a 6GHz scope and it will be interesting to see whether Agilent, Tek or LeCroy has the most abominable interface. "Which is the long version of saying that the author has no clue how the user interface of a modern day digital scope looks like.So to summarize, the author prefers digital scopes because he had some bad experience with some >15yr old DSOs of which at leats one he even didn't understand the purpose (and demonstrated his own ignorance by ignoring his colleagues warning that this was a special purpose scope!) while having no idea of what a modern day scope looks like, and all while showing that the principle behind digital scopes is mostly voodoo to him.This is a prime example of someone stuck in the past who clinges on to the old tools he's grown up with because he never made the mental leap to the digital world.Quote"Update sloppy"? "nothing is as good looking as an electrostatic deflection CRT"? That's the level of comment you'd expect from a HiFi enthusiast when talking about record players or valve amps. Saying a DSO "updates sloppy" is a bold demonstration of utter ignorance and frankly, if your only concern is that a trace is "looking good" then you shouldn't really work as EE. Seriously.QuoteOh, yes, the Tek 222 which again is what, 20 years old? And calling a TDS220 "fancy" tells me the commenter has really no idea of what a modern scope is capable of.And this is the group you want us to listen to in terms of analog scope vs. modern DSO? Are you kidding me?QuoteReally? Where does it say that? All I saw where comments from readers of EDN, and not all EDN readers are leading engineers in large corporations. You seem to read some competency in what essentially are personal comments from random places which simply isn't there.Also, my experience working in exactly that environment (large corporations) tells me that these days the chance to see an analog scope in one of their labs is roughly the same as winning the lottery.EDIT: I just noticed that the first article was actually written in 2002 and only re-published in 2011. So that means this article is actually 13 years old! What a joke!

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 03, 2015, 11:47:18 am
content: Quote from: smjcuk on April 03, 2015, 07:47:53 amSorry but that is complete nonsense. Aside from the fact that there are tons of fully working DSOs on ebay as there are broken analog scopes, just because there are X number of scopes on offer with a dead channel doesn't mean you have the tiniest clue about how reliable this particular scope is simply because you know nothing about the number of scopes out there that are working fine and hence aren't sold for scrap.You could similarly reliable results from reading in fish guts.And btw, channels rarely go dead by themselves, usually it's users overloading them. Many better DSOs have switchable 1M/50ohms inputs which in 50ohms mode are usually limited to 5V or so. Usually there is overvoltage protection but that can't prevent excessive overloading.And it's not that dead channels are unheard of with analog scopes.QuoteYou obviously have never had the joy of finding one of the obsolete proprietary parts for certain analog Tek scopes. This aside, most analog scopes contain lots of components like mechanical switches and potentiometers that don't age well, and in case of the switches fixing them or finding working replacements can be a real pain in the arse.Modern DSOs, even cheap ones like the Rigol DS1054z that is often recommended to beginners, have the capability to easily exceed the lifespan of most analog scopes, because there are less components under mechanical stress, and ageing is compensated by self calibration routines.QuoteWell, like in most cases, car analogies are just silly. Of course it's price gouging by selling software unlocks, and it's debatable if it's morally ok (legally it certainly isn't) to circumvent the software locks, but staying with an analog scope that can't do shit while even the most basic DSO without any of the software options unlocked outperforms the analog clunker easily just because of the existence of software options is silly, really.QuoteIf your lecturer really belives this then maybe he should better stop teaching and go back learning the basics then, because the algorithms used in DSOs are pretty fundamental knowledge of signal processing, and there are swathes of documentation available if he could be bothered to do some research.QuoteAny test instrument lies, that's a fact. Digital scopes lie, even if used properly. How much they lie is declared in the specs, which if the scope is working fine and used appropriately are completely reliable. Analog scopes lie, too, but in addition they often age worse than digital scopes, and then there are external factors like the user having to read from a scale (which often introduces even more errors) and guestimating the value, while DSOs (if properly used) present you with a measured value that is correct within the constraints of the scope's specification (which for DSOs are regularly magnitudes better than for analog scopes).What makes a good engineer is being able to deal with the uncertainties of a test instrument instead of simply avoiding to deal with them alltogether.QuoteIt is, if you're aware that you'll only see a segment of the frequency spectrum and that frequency components below a certain amplitude aren't shown, and that's not a problem.That's where being an engineer comes into play, if you don't know the basics then a DSO won't help you to vercome your lack of basic knowledge.In addition an analog scope won't tell you anything. The signal may look like a sine wave but in reality it's unlikely to be the case, and the analog scope won't tell you that there are other frequency components in the signal.QuoteNot really. Even most cheaper scopes come with 3yr warranty, and most big brands allow you to extend that (some even let you buy manufacturer warranty for a 2nd hand scope you bought from ebay as long as it isn't too old and the factory seal is still in place, i.e. LeCroy).On the other hand, the $150 you might pay for an analog clunker can quickly turn into a write-off if the CRT goes or any of the hybrids or other unobtainium parts.Now count in the generally higher reliability of DSOs and the case for sinking money in an analog scope becomes even more unconvincing.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 03, 2015, 12:01:35 pm
content: Quote from: tggzzz on April 03, 2015, 09:07:54 amFrom the same article:"By Paul Rako © 1989"Seriously?

author: mzzj
author_rank: Super Contributor
timestamp: April 03, 2015, 12:38:45 pm
content: Quote from: smjcuk on April 03, 2015, 07:47:53 amWuerstchenhund already addressed these but this is so hilarious that I cant resist stir the pot a bit more...1. Most cheap secondhand cars less than 500 euros also burn oil, have broken transmissions and rust. You get what you pay for?2. And analog scopes are easy to repair? have you ever take a look inside analog scope? It's a ****** nightmare of intermitted switches, bad potentiometers(custom models with no replacement avail) criss-crossed circuit boards, mechanical gludges and obsolete or manufacturer custom made chips and transistors.

author: Muxr
author_rank: Super Contributor
timestamp: April 03, 2015, 01:56:11 pm
content: From my limited use of analog scopes I must say I really liked the tactile feel of the switches and the instant update with no input lag. The controls are also laid out intuitively. Analog scopes also look cool. Like Tek 465 is probably the sexiest piece of gear ever made imo.It took me about 20 minutes to get accustomed to my Hameg 605, while I needed a day or so to learn my way around the Rigol DS2072A.Now granted the Rigol can do way more, but the option layout is unintuitive in my opinion. Like it took me a while to figure out how to show something as simple as Vpp, because it's hidden in the 2nd left menu (you have to hit the menu button twice to get to it), why they just couldn't put it in the same menu is beyond me, especially since they have scroll buttons on both sides.The fact that this is even a discussion really speaks to how good analog scopes were for their time.With that said, digital scopes offer so much more utility they are a no brainer.

author: Zbig
author_rank: Frequent Contributor
timestamp: April 03, 2015, 02:23:07 pm
content: Given this topic seems already FUBAR, I thought, what the hell, I might just as well throw in my two 0.01 PLN.I learned on analog scopes in my technical college. It helped me getting a reasonably good understanding of what the timebase, gain, X and Y deflection, etc. really means. It was easy for me to visualize how the thing really works, e.g. how the timebase setting affects the sweep rate, which really meant how fast the beam traveled physically from left to right. Or how the sweep circuit actually waited for the trigger condition to be met until it fired up the beam across the screen. It all made perfect sense so when I got my first DSO years later, I had no trouble understanding all the UI analogies. So the brief encounter with CROs and all the theoretical background I had to absorb learning them, certainly didn't hurt in my case. I tried to imagine how my learning curve would look like had I started with DSOs from the clean slate and - frankly - I have no idea. But I tend to think that I would just take more things on "oh, it's just the way they've done it" basis, without imagining the travelling beam of electrons below the phosphor layer, etc. But would that necessary be a bad thing? Im not sure, really. Perhaps just reading on some history in the Internet would be all I ever needed.That said, I did, in fact, at some point (years before I got my DSO) aquire some old, battered CRO from the technical university, when they were in the process of replacing their gear. The damn thing weighed a ton and took half of my desk. It had a nasty case of "noisy" pots, almost all of them. Not your usual, garden variety pots, mind you, but some ganged-up (sandwitched, if you will) type. The general crustiness and appearance of the thing made me chuck it in the corner of the room and never look at it ever since. Besides, I was mostly into digital and debuging of rare/one-off events so it would be of dubios help, at best.Let's be frank, when in this year an age some new guy goes like "I'm new to electronics, please advise", you can, without any further questions, pretty much assume he'll most probably start with something along the lines of Arduino lighting up an LED based on an I2C sensor data (and I don't mean that in the derogatory way) rather than building an FM receiver from discrete parts. Knowing that, projecting your "ye-olde ways I'm used to doing things since forever" on the guy is just ill-advised. If anything, this could make him get some old non-functional, irreparable or marginal at best, piece of junk, which wasn't well suited for the kind of work he's into in the first place on eBay, and then losing all interest in electronics because "screw that, that's too hard". When someone is into woodworking, you don't tell him to go get an oldest, broken, pre-WWII hammer with a handle falling off.EDIT:And there are the hipster types, I've encountered those too (not a reference to anyone here): "Oooohhh, it's sooo vintage. From now on, I'll pretend I'm old enough to remember using those (when his parents were still kids, apparently) and will keep telling everyone analog is the only way to go (in low voice, stroking his beard)". Those guys, I just give a quick laugh and move along.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 03, 2015, 03:49:48 pm
content: Quote from: Zbig on April 03, 2015, 02:23:07 pmThis a thousand times!It's fine when some forum members seem to be unable to make the mental leap in the modern age and want to cling on to their old habits, fair enough. Just don't drag newcomers down to your outdated methodology and ruin their experience. And when we're at it, maybe also stop justifiying your obsession about your perceived superiority of analog scopes with articles from over a decade ago. It's a little embarassing and if anything just shows that you're stuck in a past that has long left behind by most of the world.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 01:16:18 am
content: If you understood how to repair that This Tektronix 465, you might actually know something about electronics. If you're such a electronics smarty pants, can YOU design a Tek 465 from scratch with no help from google, books, or any other assistance?BerniceQuote from: mzzj on April 03, 2015, 12:38:45 pmWuerstchenhund already addressed these but this is so hilarious that I cant resist stir the pot a bit more...1. Most cheap secondhand cars less than 500 euros also burn oil, have broken transmissions and rust. You get what you pay for?2. And analog scopes are easy to repair? have you ever take a look inside analog scope? It's a ****** nightmare of intermitted switches, bad potentiometers(custom models with no replacement avail) criss-crossed circuit boards, mechanical gludges and obsolete or manufacturer custom made chips and transistors.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 01:20:38 am
content: Was that the year laws of Physics changed for you?Wanna another roll like this one, lipstick on the wave blunder?https://www.eevblog.com/forum/testgear/used-spectrum-analyzers-for-under-$1k/120/BerniceQuote from: Wuerstchenhund on April 03, 2015, 12:01:35 pm

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 01:24:43 am
content: Wow, some one who actually UNDERSTANDS why there is a need for both analog and digital time domain instruments.Reality is, they actually COMPLEMENT each other.BerniceQuote from: tggzzz on April 03, 2015, 08:51:28 am

author: nctnico
author_rank: Super Contributor
timestamp: April 04, 2015, 01:35:24 am
content: Quote from: WuerstchenhundI couldn't agree more.About 2 decades ago I bought a Tek 2030 which was an analog/digital oscilloscope. One where you could push a button to select between analog and digital mode. Not long after that the analog/digital button stayed in digital mode until I sold it. I have been buying DSOs since then.

author: Wim_L
author_rank: Regular Contributor
timestamp: April 04, 2015, 01:46:08 am
content: Quote from: Rupunzell on April 04, 2015, 01:24:43 amThey used to. Analog scopes used to be the standard general-purpose tool, and were quite expensive. Digital was for special purposes (the things analog couldn't do well), and even more expensive. High cost, sometimes awkward user interface and sluggish performance meant they weren't suitable as general purpose devices.Today, digital scopes are much cheaper than they used to be, even cheaper than analog scopes used to be, and the analog scopes are becoming extinct. Digital scopes are now the new general-purpose device, and their user interfaces have changed to reflect that reality. They're no longer the cumbersome beasts they used to be. Features like fast sampling, deep memory and peak detect modes also make some of the old pitfalls (aliasing) avoidable.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 02:14:42 am
content: DSO's actually fit the current generation of digital design and computer centric needs better then CRT-analog time domain instruments.Learning how to interpret the display on a analog CRT display is likely one of the most difficult skills to acquire along with proper test-set up and understanding what happens to the DUT when probed.It is the difficult with interpretation that makes DSO's so very appealing in many ways. Other factors, analog folks do not need to know precise timing and absolute amplitude accuracy as the information presented happens between 0 to 1 is what matters, not 0 or 1.How many modern DSO's offer 10uV per division differential inputs, or can be over driven by more than 8-10 display divisions and not present false information? I'm still very suspicious of how much digital noise comes out of any DSO. Meeting emissions requirements along is not a assurance these digital devices does not dump digital switching noise into the power mains and overall test set up. Digital folks might not care, analog folks who are dealign in nano volts/nano amps do. Then we have user interface, I can operate a Tek 7000 by feel as each knob, button has a fixed location and fixed function which means there is a fixed map of what each control does.. instead of scrolling over menus, poking at soft keys or poking at a touch screen to drive the thing. Oh, it is not as easy to get an analog CRT scope to lie about what is happening. If there is mis-information, better figure out why for both analog CRT or DSO.Then we get into the mixed domain DSO where the added feature is FFT, which IMO becomes jack-of-most trades and master of none. As for the data export to Matlab and such, kinda handy no? Except, is that test set-up actually honest and telling the truth?Point being both analog CRT and DSO have their place and those who are wise will apply the appropriate instrument for a given measurement requirement.BerniceThey used to. Analog scopes used to be the standard general-purpose tool, and were quite expensive. Digital was for special purposes (the things analog couldn't do well), and even more expensive. High cost, sometimes awkward user interface and sluggish performance meant they weren't suitable as general purpose devices.Today, digital scopes are much cheaper than they used to be, even cheaper than analog scopes used to be, and the analog scopes are becoming extinct. Digital scopes are now the new general-purpose device, and their user interfaces have changed to reflect that reality. They're no longer the cumbersome beasts they used to be. Features like fast sampling, deep memory and peak detect modes also make some of the old pitfalls (aliasing) avoidable.

author: Wim_L
author_rank: Regular Contributor
timestamp: April 04, 2015, 03:29:41 am
content: Quote from: Rupunzell on April 04, 2015, 02:14:42 amThe vast majority of analog scopes do not offer those features either, you're talking about some very specific plugins for certain analog mainframes here. Now, if you're willing to use some fairly expensive external tools, just put a sensitive preamp in front of the scope and any model, analog or digital, will do it. Something like this:http://www.thinksrs.com/products/SR560.htmAbout the noise, well, it depends. I've seen digital scopes which were terrible, and some which were quite good.This might depend more on the type of power supply than on the measurement side.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 03:46:17 am
content: Tektronix 7A22. Initially offered as a 1A7A circa mid-60's. Tek the offered this same differential section as 5A22N and for the TM500 as AM503, 5030 dual beam oscilloscope. Adding a "pre-amp" is not as easy as one might believe as this Tek offering has 120db CMMR, adjustable LF * HF bandwidth limits (1 Mhz)and DC offset all at once.The Tek 7A13 has much the same performance as the LeCroy-Teledyne-Preamble differential amplifier add on. Current market cost for the 7A13 plug in about $50 USD, check the current market price of the LeCroy-Teledyne-Premable 1855. The performance of these two differential amplifiers is limited by what is possible in silicon JFET technology.How many time domain instrument users need these capabilities and do they know how to get the very most measurement capability out of them?This is some of what separates highly experience and skilled users from lesser users.BerniceQuote from: Wim_L on April 04, 2015, 03:29:41 am

author: miguelvp
author_rank: Super Contributor
timestamp: April 04, 2015, 05:45:14 am
content: Well,The 7A13 differential comparator was $2,865 in 1983. (source:http://en.wikipedia.org/wiki/Tektronix_analog_oscilloscopes#7000_series)Rigol's 100MHz differential probes are $750 (source:http://www.tequipment.net/Rigol/RP1100D/Active-Differential-Oscilloscope-Probes/)They offer lower bandwidth probes for as low as $450 new if 25MHz is good enough for you, or 50 MHz for $650. Of course you can apply the EEVblog discount code.As nice as the 7A13 is, it takes a full bay, the Rigol accessory doesn't limit the number of channels your scope can have since it attaches to the channel you want to use.BTW I just got a 7A13 and yes it's nice but only because it cost me peanuts, I got all those 3 modules for $36 total shipped, the one of the left is actually a 7A11 but the pull tab was missing, I have a single channel 7A15A that is a mess with broken knobs etc, so I re-purposed the tab (some whiteout and drawing a 1 on top will do)The 7A11 has a built in probe inside with accessories hiding behind that yellow backed bnc connector.

author: miguelvp
author_rank: Super Contributor
timestamp: April 04, 2015, 06:12:12 am
content: Oh, and mine didn't come with 10 uV per division just a mere 1 mV which is better than the usual 5 mV most modules have.I do prefer the DSO since it can show the noise the 7613 with the 7A13 hides.Edit: BTW that is a 40mVpp signal using an x10 probe, so it should show 4 divisions like the Rigol instead of 2. Weird.Edit2: Also the 1KHz test signal using the 40mVpp signal is not really 1KHz.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 06:21:30 am
content: Rigol's diff probe has 50db CMMR at 1 Mhz as spec. What is might the CMMR be at say 100Mhz, it will not be 50db.http://www.tequipment.net/Rigol/RP1100D/Active-Differential-Oscilloscope-Probes/No spec for noise, over drive recover time, dc shift due to over drive and .... There is a bit of spec's game with their max CMMR voltage.Compare that to a Tektronix P6046, spec'd at 60db @100 Mhz.http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%20P6046%20Instruction.pdfThese cost a lot less on ebay and at swaps. I have several of them and they all get used. They are FRAGILE if abused and the user must know how to use this probe properly. This is part of their performance tradeoff -vs- being robust against user abuse. Calibrating them is GREAT fun as with adjusting the attenuator to have good overall CMMR at HF. and they can be applied to as many inputs as available.That 7A13 is the older version with the mechanical comparator voltage readout. The later ones have a DVM in place of the mechanical system. They both work equally well. A DVM can be connected to the Vc out to get more accurate reference readings if needed. Have several of these too. Note worthy about the 7A13 is it's over drive recovery time and CMMR. It's limitation is once the DUT is moved away from the input connectors, the CMMR becomes degraded. A reality that holds try for most any diff input device. This is where using the P6046 properly is the better way. Regardless, using these specialized diff input devices are not for the common everyday measurement. One more interesting feature about the 7A13, on the left hand side of the plug in is a switch that removes the input attenuator termination resistor. This results in very high input impedance (kinda close to infinity) limited by the input current match between the two 7A13 inputs. What modern time domain instrument diff amplifier has this feature? Consider what this feature might be used for?Tektronix also made a current probe plug in for the 7000, 7A14 that is designed to be used with their transformer based current probes. Eventually, Tek introduced the Type 134 with much the same abilities. These can be applied to as many channels as available.There was also an A/D sample hold plug in for the 7000, 7D12 with modules.And the host of sampling plug ins, TDR plug ins and...BerniceQuote from: miguelvp on April 04, 2015, 05:45:14 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 04, 2015, 06:32:59 am
content: Your 7A13 is out of whack or there is a problem else where. 7A13 goes down to 1mV at 100Mhz. The 7A22 goes down to 10uV at 1 Mhz.If time permits, I'll post some similar images of the 7A13 and 7A22.As for DSO noise, post processing will have an effect of displayed noise.. as the data will be filtered in some way. How, that depends on a host of DSO settings, manufacture choices and related. How does one know, measure or confirm the amount of digital switching noise that is coming out of a DSO's switching power supply that is getting back into the test set up's mains power and else where (via ground currents)? What about switching transients from the DSO's inputs, how much isolation does the DSO have between the A/D, it's internal digital processing and it's inputs and chassis ground?Would I trust using a DSO for noise measurements on the analog stuff, not really.BerniceQuote from: miguelvp on April 04, 2015, 06:12:12 am

author: miguelvp
author_rank: Super Contributor
timestamp: April 04, 2015, 07:15:13 am
content: Much better now (with ground spring), although it keeps on jumping to two division, but changing the Volts/div to 2 mV and back to 1 mV get's it back.Lowered the intensity to see more detail on the 7613:I just hope is not the miniature relays that is causing the volts/div to half every now and then or I'll have to deal with this:(with google translate from German to English)https://translate.google.com/translate?sl=auto&tl=en&js=y&prev=_t&hl=en&ie=UTF-8&u=http%3A%2F%2Fwww.amplifier.cd%2FTest_Equipment%2FTektronix%2FTektronix_7000_series_amplifier%2Famplifier_7A11.htm&edit-text=And this to find out which ones are broken:http://ik1zyw.blogspot.co.at/2007/09/tektronix-7a13-broken-relays.htmlBut it seems the 7A11 I got, also has the same relays.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 04, 2015, 08:18:29 am
content: Quote from: Rupunzell on April 04, 2015, 02:14:42 amDSOs actually fit both, digital design as well as analog design much better than analog scopes.QuoteTrue, but you can learn that equally well with a DSO.QuoteThat's simply not true. There are lots of applications where timing and amplitude of an analog signal is relevant.QuoteHow many analog scopes do (the answer is very few)? This aside, as already mentioned there are external amplifiers like the LeCroy 1855A which do that.And the only reason you have to overdrive the inputs in an analog scope is because it's the only way to see more details of a part of the signal. That archaic method is completely unnecessary on a DSO which easily zooms to any part of the signal that interests you.QuoteThat's nonsense. First, "digital folks" very much care about noise, because just because digital systems are generelly less sensitive to noise doesn't mean it's a non-issue. Second, I can't talk for bottom-of-the-barrel DSOs but any proper DSO from the big brand offers very clean voltages on their PSUs secondary side, something that can't always be said about analog scopes.And just because your analog scope doesn't show noise doesn't mean it's not there. Especially noise is often not shown on analog scopes because it just goes under in the overall glooming of the trace on the phosphor.QuoteI don't know what you guys have with user interfaces but even on my high end LeCroy scope I wouldn't have to use the touch screen or go into any menu if all I wanted was to use the scope in the same way as an analog scope. And that is a scope that due to the sheer amount of capabilities (it's more a signal analyzer than a scope) does have a lots of menus and settings.Basic scopes like the Rigol or Agilent DSOX also have all relevant buttons on the front, and if you were to overcome the aversion against anything digital in your mindset then it shouldn't really be difficult to use one of these DSOs.QuoteAnalog scopes lie, a lot, just not in a very obvious way (they tend to hide information). Digital scopes only lie if you ignore the fundamental limitations of the particular scope (i.e. sample rate), and if they do it's usually pretty obvious (to somewhat experienced users at least).I've lost count of the occasions where some engineer who grew up with analog scopes thought the DSO must be lying when it fact it was that the DSO was showing signal components he never saw on his analog scope.QuoteNewsflash: Mixed Domain is *not* FFT. Most of the early day DSOs (the ones from 20 years ago you usually take as examples to explain why DSOs suck!) didn't have FFT or only as an option, but for the last 15 years or so FFT has been pretty much a standard feature of DSOs.Mixed-Domain refers actually refers todigital inputs (i.e. logic analyzer) which a MSO offers in addition to its analog inputs.(Tektronix) scopes with integrated Spectrum Analyzer.QuoteYes, it is. Like every test instrument it's only as truthful within the constraints of its specs, but a DSO is still much more truthful than any analog scope can ever be.QuoteYes, analog scopes have their place, which in these days is a museum. I appreciate that this is difficult for you to understand (since your awareness of DSOs seems to be limited to what was available >15 years ago) but in 2015 there is really no reason why one should choose an analog scope over a DSO.EDIT: mixed up MSO and MDO - corrected.

author: miguelvp
author_rank: Super Contributor
timestamp: April 04, 2015, 09:32:13 am
content: One more thing, DSOs are analog scopes on the front end, because there is no other way around it.Front ends now are much better than back then, the sampling is way higher than old DSOs and the menus are intuitive, at least they are for me.But because analog only scopes do hide information, they are cool to use for vector graphics based on sound. Digital ones can't really hide well the low level traces connecting what is intended to be viewable.

author: GK
author_rank: Super Contributor
timestamp: April 04, 2015, 09:55:49 am
content: My old Philips analogue scope is way easier to service than any crappy fancy schmancy DSO. Still going ~70 years on! Ha! End of discussion.

author: tautech
author_rank: Super Contributor
timestamp: April 04, 2015, 10:24:43 am
content: Quote from: GK on April 04, 2015, 09:55:49 amNot really.BW?But really nice ol' Tek Glen.

author: G0HZU
author_rank: Super Contributor
timestamp: April 04, 2015, 11:04:45 am
content: Quote from: Wuerstchenhund on April 04, 2015, 08:18:29 amI'm not really that interested or clued up about the modern scope related marketing terms but I thought that 'mixed domain' was a Tektronix marketing term for a range of their scopes that offered both time and frequency domain measurements to be made together.i.e. a mixed signal scope (MSO with analogue and digital inputs) combined with an FFT based spectrum analyser = MDO.

author: miguelvp
author_rank: Super Contributor
timestamp: April 04, 2015, 11:07:55 am
content: Quote from: GK on April 04, 2015, 09:55:49 amFor servicing, Nothing beats a Tek 5110 with 5A24N modules (2 MHz)Well, nothing other than a string and some cans

author: Howardlong
author_rank: Super Contributor
timestamp: April 04, 2015, 12:13:30 pm
content: Quote from: G0HZU on April 04, 2015, 11:04:45 amThat is my understanding also. Mixed domain, as in measurement in both time and frequency domains, much as we say an regular oscilloscope is a time domain instrument and a spectrum analyser is a frequency domain instrument.

author: mzzj
author_rank: Super Contributor
timestamp: April 04, 2015, 01:03:14 pm
content: Quote from: Rupunzell on April 04, 2015, 01:16:18 amOne may understand how to fix POS Tek 465 and another understand how to fix it and why its not worth of fixing

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 04, 2015, 01:54:14 pm
content: Quote from: G0HZU on April 04, 2015, 11:04:45 amYou're right, my bad. MDO is indeed a marketing term coined by Tektronix for their scope which have an integrated Vector Spectrum Analyzer (which isn't quite the same as the FFT functionality in most scopes).FFT on the other side has been pretty standard in most DSOs at least since 2000.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 04, 2015, 01:55:32 pm
content: Quote from: mzzj on April 04, 2015, 01:03:14 pmHow true. Not everything that can be fixed is actually worth fixing.

author: G0HZU
author_rank: Super Contributor
timestamp: April 04, 2015, 02:35:17 pm
content: QuoteYup.One party trick the old Tek 465 can do is to connect the rear panel 'CH1 vertical out' to the RF input of a conventional spectrum or signal analyser (with a limiter inline for safety)This way you can use the 465 to probe with a scope probe in the time domain and also look at the frequency domain with the analyser. The analyser could be configured to show the frequency (or time) domain and also to demodulate the signal. All from the same scope probe. The 465 effectively becomes a variable gain RF probe with a time domain display (scope) built inYou can do similar with a modern DSO by displaying an FFT but it isn't going to deliver the same performance as a decent spectrum/signal analyser if you are looking for very small signals near very large ones.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 04, 2015, 06:04:44 pm
content: Quote from: G0HZU on April 04, 2015, 02:35:17 pmIt's been a long time since I touched a Tek 465 but if my memory serves me right the Ch1 Vert out on the rear didn't provide the signal at the Ch1 input at the front but the resulting vertical signal after the preamp and attenuator stages, and therefore was limited to the dynamic range of the scope's internal amplifiers. I very much doubt that the resulting dynamic range was any better than what you can see on a DSO using FFT, especially when considering that the Tek 465 didn't had the most sensitive input section anyways.

author: paulie
author_rank: Frequent Contributor
timestamp: April 04, 2015, 07:31:56 pm
content: Quote from: mike_mike on April 01, 2015, 05:22:12 pmAs usual forum noisemakers totally ignore content of the oiginal post. Most probably don't even bother to the read even the previous post before shooting off. Then they ask "Where did OP go? How rude!". LOLAnd did I ever mention very free with other peoples money? In this case not a single answer so far to the question "Can you get a DSO for under $100". Well, it's "No", unlike hundreds of analog deals ranging $20-$50.Ignoring all the apples/oranges he says she says, bottom line is DSO lets you peek past and future whereas analog is for NOW!! All the other garbage is pretty much blah blah blah for most hobby use. Of course the 0.01% hobby snobs posing from in front of their wall of over-priced gear will disagree.

author: G0HZU
author_rank: Super Contributor
timestamp: April 04, 2015, 07:44:02 pm
content: QuoteI hope that wasn't aimed at me?The old Tek 465 can be bought for peanuts these days if you are patient. I paid about £50 for mine way back in the 1990s.I still use it today and a 465 is definitely worth considering as a cheap first scope if the budget is low.It can still be useful even to a professional and I gave an example trick it can do. The OP could do the same with a soundcard to replace the RF spectrum analyser at the rear CH1 vertical.So, if we consider the original requirement of the OP you can probe a PSU for ripple in mixed domain using a 465 and any old PC from the last 15 years that has a soundcard and is running a basic (freeware) spectrum analyser program. Just connect the PC soundcard to the rear Ch1 vertical input of the 465 and you have a low frequency spectrum analyser for free as you probe with the scope and a x10 probe or a direct screened/shielded connection or a differential probe. You could also capture the ripple with the soundcard as a wav file and postprocess it and look at it in the time domain or frequency domain.

author: Wuerstchenhund
author_rank: Super Contributor
timestamp: April 04, 2015, 08:07:55 pm
content: Quote from: paulie on April 04, 2015, 07:31:56 pmHad you actuallyreadthe thread, instead of just ranting ahead, then you might have noticed that the OP's question has been answered within the first number of replies (and many people recommended to save just a bit more and get a DS1054z instead of getting an old analog scope now). This way You also would have noticed that there where some questions for the OP to clarify, too, to which he never replied, but yeah, I understand that I'm probably expecting a bit too much there.

author: paulie
author_rank: Frequent Contributor
timestamp: April 04, 2015, 08:16:18 pm
content: Funny you should mention soundcard. For the purpose of this thread there are dozens of software based scopes available for free download. You can't get much cheaper than that. And even considering hardware stand-alone DSO I should take back about not getting for under $100. Those DSO201 ARM based "pocket scopes" can be had for about half that:http://www.ebay.com/itm/Portable-Mini-Nano-ARM-DSO201-Pocket-sized-Handheld-Digital-Storage-Oscilloscope-/251801605488?pt=LH_DefaultDomain_0&hash=item3aa08b9570Certainly adequate for what mike-mike needs and for that matter the even cheaper (~$30) AVR based dealies would suffice.

author: tautech
author_rank: Super Contributor
timestamp: April 04, 2015, 08:24:00 pm
content: And while we are looking at cheap measurement options for the OP, if he has a reasonable DMM, it should give him a good idea of ripple on a PSU if the ripple is within the frequency range of his DMM.AC mV.

author: paulie
author_rank: Frequent Contributor
timestamp: April 04, 2015, 08:35:40 pm
content: True, DMM will be quite useful for judging how much ripple. Unfortunately in many cases, as hinted in a recent electronics thread, the waveform can be even more important. Specially for a switcher and you want to determine if it's working properly and best way to fix if not. Or if it is working but noisy and you need to filter.

author: G0HZU
author_rank: Super Contributor
timestamp: April 04, 2015, 10:06:47 pm
content: QuoteI think it's front end sensitivity is quite good. Maybe you can give me some figures for what noise figure you think it has across most of the 100MHz input bandwidth?When coupled to a spectrum analyser it can also easily display two test tones and show about -75dBc 3rd order IMD levels (for a signal waveform that fills the CRT) and this is probably 15dB better than many 8 bit DSOs can manage in FFT mode.Then there is the issue about annoying alias terms in the DSO FFT that won't be there in a conventional spectrum analyser connected to a 465. So far fewer annoying phantom alias terms to worry about.I usually use an active RF probe straight into the analyser for stuff like this but not everyone has a decent RF probe. The Tek 465 can act as a very robust RF probe with variable gain via the front panel Y controls and this can feed a hobby spectrum analyser or a counter or a receiver. Its front end can provide some signal gain as well and I can easily look at signals of <<0.5uV amplitude this way (i.e. arriving at the 465 CH1 and then displayed on the analyser via the CH1 rear output) .Note: it's best to fit a DC block and a limiter inline between the 465 and the analyser if the analyser doesn't have an internal DC block and also has a lowish damage level.It's a cheap and effective option

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 05, 2015, 02:40:29 am
content: How does a gaussian response system (real time) from input connector to CRT phosphor hide noise?Down load the service manual and do the performance checks. Before that omit the probes going direct from a calibrated level test generator direct to the inputs.BerniceQuote from: miguelvp on April 04, 2015, 06:12:12 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 05, 2015, 03:16:03 am
content: Here is what the 7A13 should look like at the 1mV/Div at 100Mhz and 5Mhz with a FG input. The un-used input must be set to ground or terminated or set to internal Vc or to the same impedance as the used input or the displayed amplitude could be what you're observing will be wrong. This is a basic rule of using diff input amplifiers.Text book measurements like these are of extremely limited information and telling of what the 7A13 can do in real world test set up requirements. These basic measurements are what the modern DSO's do so very well at complete with a on display box full of data. No user interoperation needed. This is the great appeal for the vast majority of time domain instrument users. These are the types of measurements that have the lowest meaningful data and usefulness for the stuff I do.7A13, 1Khz sine, 1mV/Div, 100 Mhz, single ended input:7A13, 1Khz tri, 1mV/Div, 100 Mhz, single ended input:*Notice the over shoot spike at the peak of the triangle wave.7A13, 1Khz tri, 1mV/Div, 100 Mhz, single ended input:7A13, 1Khz sine, 1mV/Div, 5 Mhz, single ended input:7A13, 1Khz tri, 1mV/Div, 5 Mhz, single ended input:7A13, 1Khz step, 1mV/Div, 5 Mhz, single ended input:For comparison, Tek 7A22.The noise spectra can be determined by usual observation in real time, in these time exposure images that data is mostly lost as the exposure time integrates the noise camera exposure time. The peak noise and much more visual information is not visible in these images. A video would illustrate this better than still images.7A22, 1Khz sine, 10uV/Div, 1 Mhz, single ended input:7A22, 1Khz Tri, 10uV/Div, 1 Mhz, single ended input:7A22, 1Khz step, 10uV/Div, 1 Mhz, single ended input:7A22, 1Khz sine, 10uV/Div, 100 Khz, single ended input:7A22, 1Khz tri, 10uV/Div, 100 Khz, single ended input:7A22, 1Khz step, 10uV/Div, 100 Khz, single ended input:*Some one with a modern new "fancy dancy" DSO need show-prove this exact measurement at 10uV/Div, 1Mhz BW and 100Khz BW at the DSO's input. NO ADD ON, Pre-amps or external aids.These inverted contact Tektronix relays were used in a LOT of tek instruments. They have very good BW and very low coupling from the coil to contacts. Over time like most all mechanical devices, they can wear out. Do wiggle them in their sockets as the sockets are know to become intermittent if the instrument is not used. Replacements can be the original Tek part or Teledyne T0-5 relays. Send me a PM if you need help with these.BerniceQuote from: miguelvp on April 04, 2015, 07:15:13 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 05, 2015, 03:19:52 am
content: Yes, the vertical amplifier sections can be cascaded to increase sensitivity. The objective of this is NOT to increase dynamic range, it is done to increase input sensitivity at the trade off of lower BW. The input might not be that "sensitive" but the inputs are low noise and low noise makes all the difference.BerniceQuote from: Wuerstchenhund on April 04, 2015, 06:04:44 pm

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 05, 2015, 03:29:27 am
content: Guess we are gong to have another roll. Try replicating the LM317 & LM337 noise current and internal band gap switching measurement posted else using your fav DSO. The image results are going to look like this, The prime trace of interest in the one in the center which is 10mA/Div. The peak current off screen is >100mA, current noise on that trace ranges from less than 1mA to just over 10mA.And.. I'm waiting for YOU to post an image of your fave DSO at 10uV/Div with a 20uV peak to peak signal.Stop typing for a moment and show us your test and measurement skills and understanding of what is happening and why.BerniceQuote from: Wuerstchenhund on April 04, 2015, 08:18:29 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 05, 2015, 03:41:27 am
content: Once an individual becomes closed minded and learning resistant, the possibility of knowledge gained is lost and the malignancy or ignorance, prejudice and discrimination within that individual simply grows.It is so very easy to criticize what one does not understand and discount the knowledge and expertise offered. If the scientific community had this attitude and ideology, the very foundation of science and technology would mostly fall apart.These statements also says much about those who wrote them.BerniceQuote from: Wuerstchenhund on April 04, 2015, 01:55:32 pm

author: tggzzz
author_rank: Super Contributor
timestamp: April 05, 2015, 07:01:35 am
content: Quote from: Rupunzell on April 05, 2015, 03:41:27 amTrue, unfortunately.

author: mzzj
author_rank: Super Contributor
timestamp: April 05, 2015, 07:50:22 am
content: Quote from: Rupunzell on April 05, 2015, 03:16:03 amSOME of the old analog scopes definitely have nice to have features but how many analog scopes out there you can find with 10uV/div sensitivity?This side of the pond ie. tek 7000 is nearly impossible to find, I have yet to see mainframe scope in their natural habitat. Your situation in US might be better.Back then I had to use external preamp with my analog tek 475 and still have to use external preamp with my current DSO.

author: miguelvp
author_rank: Super Contributor
timestamp: April 05, 2015, 08:46:43 am
content: Well I did move the 7A13 to my 7603 because the screen is bigger than the 7613.And I fed it a 26MHz 4Vpp signal, because at 1KHz you have all the time to sample that. Also because the only FG I have (Tek FG504) gave up it's magic smoke and my attempts to fix it have not succeeded yet. (Back plane transistor failed taking out who knows what on the module, fixed the backplane and replaced a on board fuse and more smoke came from somewhere else)Anyways, the 7A13 had no trouble at all with the 26MHz signal, I even use the x10 magnification on the time base to look at the signal in detail with 5ns divisions. Probe is still a x10 probe so the voltage divider is set at 100mV and the signal is AC coupled.Looks good, so I took the probe bnc and attached it to the Rigol, but to make things fair I did set it to 100MHz bandwidth limit.The signal looks very similar, other than the Rigol starts with a sharper rising edge and a sharper falling edge, other than that, pretty close, if you don't take into account the extra 4 horizontal divisions and that the Rigol can still go to 2ns and 1ns per division.So I took the bandwidth limit off and I see closer to the square wave I'm expecting from the 26MHz OCXO.I know, they do make mainframes and modules that can go to a higher time base but the 7A13 is limited to 100MHz and the 7A22 which is nice that it can do 10uV per division, but is limited to 1MHz.But then again at 10uV, 1 us per division should be plenty.Btw I'll receive a 7A22 sometime this coming week since I did purchase it a few days ago along with a couple of dual trace amplifiers. Got all three for $12 a pop including shippingOnly thing is that the 7A22 is missing the pull tab.

author: miguelvp
author_rank: Super Contributor
timestamp: April 05, 2015, 08:53:48 am
content: Quote from: mzzj on April 05, 2015, 07:50:22 amI got a 7613 for under $50 and extra modules for about $12 a pop shipped and I already had a 7603. Nobody seems to want them because they are heavy and bulky and unless you find one locally it would be too expensive to ship.The thing is that I don't know how usefull 10uV/div is at just 1MHz, but I guess I'll find out since I have a 7A22 heading my way.Btw, my plan for the 7613 (rackmount) is to get it all nice and calibrated and giving it away to the local hackerspace. (That is if they want it, if they don't I'll see what I do with it). But I'm keeping the 7603 and of course the best modules.

author: mzzj
author_rank: Super Contributor
timestamp: April 05, 2015, 09:02:36 am
content: Quote from: miguelvp on April 05, 2015, 08:53:48 amThis. Last time I checked the shipping to europe would have been something like 600 USDVertical amplifiers would be small enough for transport if there is a reasonably easy hack to use them on the dreaded DSO's

author: KJDS
author_rank: Super Contributor
timestamp: April 05, 2015, 09:03:29 am
content: Blimey, a bloke asks about buying an old Ford Cortina, which will do the job ok providing he can wield an oil can and a set of spanners and we get pages of discussion about the various merits of a Ford RS200 vs a Toyota GT86

author: miguelvp
author_rank: Super Contributor
timestamp: April 05, 2015, 09:29:12 am
content: But one thing is for sure, my DSO is lying to me on the BW limiting to 100MHz because it seems it's only filtering part of the signal.I do like both analog and digital scopes but I have no need for just an analog one because most of the things I do require time precision and memory to see all those fast bits going by on current protocols. No Ethernet nor USB yet and for that maybe an analog scope will be better than an expensive DSO that can do a good eye diagram, I know mine is slow as molasses for that task.So here are some pictures merging both technologies and that shows my DSO is not filtering the signal:Sorry they are not 100% squared because I didn't want to take time correcting for the angle of the 7603 picture, but it's close enough, and the truth is not in between those signals

author: GK
author_rank: Super Contributor
timestamp: April 05, 2015, 02:18:54 pm
content: Quote from: tautech on April 04, 2015, 10:24:43 amNot much beyond audio.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 06, 2015, 02:42:10 am
content: Check for shorted dipped tantalum capacitors in that FG504. Tek gear from that era was notorious for using short prone tantalum capacitors (those blue blobs that short can get hot and surprise).About 100Mhz is pretty what the 7600 series will do The attraction of the 7603 is CRT display size. Using a wider BW plug-in will not increase the effective overall system BW. A 7603 or 7633 or 7623 makes a nice host for the 7A13, 7A22, 7A18 with the 7B53A dual time base. These also work well with the sampling, TDR, logic analyzer, digitizing vertical and spectrum analyzer plug ins. It's limitations is BW. IMO the ideal 7000 series is the 7904A and 7104 or if dual beam is needed 7844.Careful if the pull tab is missing, that is the locking latch. If it is missing and the plug in is installed into a MF, it can get stuck and not fun to remove. Replace the pull tab, make a similar pull tab in place of the original or remove the locking latch parts and spring on the bottom of the plug-in.If the dual trace verticals have what appears to be intermittent attenuators, I have the cure. The cure is not cleaning the switches alone. Let me know.BerniceQuote from: miguelvp on April 05, 2015, 08:46:43 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 06, 2015, 02:49:54 am
content: Don't hack up a 7A22 just to be used with a DSO (DSO's are NOT dreaded, they have their place and are invaluable for specific measurement needs) get a Tek AM502 for use in a TM500 main frame. These have the same identical innards as the 7A22, 1A7A, 5A22N except configured to be used as a stand alone amplifier.http://w140.com/tekwiki/wiki/AM502These have much the same performance and relevant features as the Stanford Research Instruments SR560.http://www.thinksrs.com/products/SR560.htmThe Tek AM502 has adjustable DC offset the SR560 does not, it has more filter options as feature fillers IMO.BerniceQuote from: mzzj on April 05, 2015, 09:02:36 am

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 06, 2015, 03:33:14 am
content: The DSO is not quite "lying", it is more the, "Mr. Gibbs" effect. Information systems that reconstruct information from points of data will need to have these points of data connected in some way (filtering) to re-construct the the information that was acquired. Once the BW is limited in these systems, the Gibbs phenomenon becomes reality and becomes more pronounced when the required information to be reconstructed approaches the Nyquist limit (two samples). For DSO's that have plenty of reserve BW, they can be tailored to deliver Gaussian response at the trade off of absolute BW capability. This is why DSO's can "lie" and true Gaussian response analog CRT O'scopes do not have this issue. In the case of this Rigol DSO, some one in the design process had to decide and make a choice between BW limit and displayed response. With the BW limit on, the Mr. Gibbs ears appear on the trailing edge of the step response and the leading edge is not quite Gaussian response.The BW limited images with notes:The full BW image with notes. The near identical match of sweep linearity between the analog Tek and Digital Rigol says much about how good the sweep generator is in the 7B53A as they are near identical in length and overall linearity. Mr. Gibbs is clearly visible on the leading and falling edges of the DSO trace. Does this matter, it depends. For doing digital stuff where timing precision matters, measurement ease and features are key, those Gibb ears often make NO significant difference at all. For high speed, wide BW analog designs, it can be a serious limitation rendering this DSO mostly useless as it would be extremely difficult to know if the Gibb ears are adding or subtracting from or to the DUT's actual response. Beyond this, user must be be extremely aware if the aberrations are test set up related, instrumentation issues or meaningful information.This is a 10mV, 25Mhz step (square wave) from a Tek 2101 pulse generator to the Tek 7104, 7A29 & 7B10 with proper cables and terminations . This system offers 1Ghz real time true Gaussian response. Note the symmetry of the step response up/down and low noise even at 10mV/Div.On the Tek 7603 image, that bump at the top of the step response could be due to probe reflections or other test set up related.BerniceQuote from: miguelvp on April 05, 2015, 09:29:12 am

author: mtdoc
author_rank: Super Contributor
timestamp: April 06, 2015, 03:45:50 am
content: Great stuff Bernice. Thank you!No longer will I think of that guy from Pirates of the Caribbean when I hear "Mr Gibbs"

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 06, 2015, 03:48:09 am
content: 7A22, 1Mhz, 10uV not just for audio.*Electro-mechanical systems.*HUGE array of sensors from microphones, hydrophones, optical sensors, vibration sensors and...*Thermocouple effects including their time constants.*Current sensing resistor testing.*Dielectric testing of materials.*Biological-electical phenomena.*Chemical-elecrical phenomena.*Power supply noise and regulation testing.*Low noise amplifier design.*Charge pump design.*Frequency discriminator design.And a whole lot more limited by imagination, creativity and a deep understanding of how to apply an instrument with these capabilities. Beyond all that, the specific measurement needs and how to gain accurate and useful information about the DUT becomes what matters.BerniceQuote from: GK on April 05, 2015, 02:18:54 pm

author: nctnico
author_rank: Super Contributor
timestamp: April 06, 2015, 04:04:43 am
content: With an external amplifier you can do the same low level stuff with a DSO. And since most have FFT and other goodies life is much easier when using a DSO.It's great you are enthousiastic about your analog scope. IMHO the modular system Tektronix offered in the past where a great way to turn a mainframe into a versatile tool. Nowadays most of the useful features are integrated into a DSO. For example: I wouldn't want to live without cursors which tell me the time difference, frequency and amplitude of a signal as a number.

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 04:34:15 am
content: Quote from: Rupunzell on April 06, 2015, 02:42:10 amThanks I might get around fixing it, it's a pretty good FG, and the TM503 is not a monster size-wise.Quote from: Rupunzell on April 06, 2015, 02:42:10 amIt is what I have, a 7603 that had a busted dual trace that I just repaired:https://www.eevblog.com/forum/repair/repairing-tektronix-7603-oscilloscope/And a 7613 that I just got at auction last week (with a 5110) that were in pretty bad shape:But I just finished cleaning them:My purpose for the 7613 is to donate it to the local hackerspace, I still need to calibrate it and decide what modules to give with it.The 7603 I'm keepingThe 5110 will go to the hackerspace as well as soon as I find a time base module for it. As I got it, it has an amplifier (2MHz) driving the horizontal. No idea how they where using this thing without a time base module, it doesn't work that great as an X-Y low frequency tracer. I mean it does work somewhat but it's a weird configuration how it came.That would be good for Audio or to use it as an X-Y display or a curve tracer. The display is pretty nice and big.Quote from: Rupunzell on April 06, 2015, 02:42:10 amI have long pair of straight and narrow tweezers that can reach the release button via the pull tab hole and press it up to release, but I have an extra 7A15A module that I'm using the tab that it had on modules that don't have a tab.Found tabs online but not with the pin or the spring, maybe I'll ask a friend to 3d print some for me, or make a mold and make some copies.Quote from: Rupunzell on April 06, 2015, 02:42:10 amWell, not sure about the dual trace verticals, but the 7613 intensity readout is intermittent. It mostly works but the readouts disappear when I'm changing the intensity.The dual trace amps should be here sometime this week, probably tomorrow. I also got a 7D15 225MHz Universal Counter/Timer that I got from ebay and that will arrive sometime this week as well.Don't get me wrong, I love old gear, and so far I did spend $160 on the 7613 and the 5110 with 7 modules, on top of the 3 that the 7613 came with and the 2 the 5110 has.But the only reason I'm getting this is to help a bit the community a bit and because I hate equipment go to waste when it's pretty useful still.

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 04:36:32 am
content: Quote from: Rupunzell on April 06, 2015, 03:48:09 amHe was not referring to the 7A22 but his 70 year old valve Philips Analog Scope:https://www.eevblog.com/forum/testgear/my-first-oscilloscope/msg644542/#msg644542

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 04:43:01 am
content: Quote from: Rupunzell on April 06, 2015, 03:33:14 amI'll take some of the credit for calibrating the 7B53A and adjusting the gain of the 7A13 to match the Rigol and my DMMBut yeah, they match because I used the Rigol as the reference since I don't have other references (yet).

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 04:47:58 am
content: Quote from: mtdoc on April 06, 2015, 03:45:50 amAnd I agree, great information!My oscillator was 4 Vpp same probe on both readings x10 Rigol probe with ground spring, distance on the OCXO between the signal and ground was 0.4 mils (4 breadboard holes)The OCXO is a Vectron OCO700-13B 26.000MHz powered by an HP E3615A set at 4V 0.65A current limit and my DMM UT71B was reading 4.04V out of the PS, same reading as the Rigol at full bandwidth.At 100MHz BW limit the Rigol was showing 4Vpp so I adjusted the 7613 to match it.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 06, 2015, 04:59:14 am
content: Simple, easy test to try with the 7A13, power supply testing.*Put a 10x (compensated to the 7A13's input) or 1X probe to the + input of the 7A13.*Ready a power supple for test, note it's voltage to be tested.*Set the Volts/Div on the 7A13 to two or so Volts/Div of the power supply's output voltage.*Set the trace to a reference line using the 7A13 vertical position knob. There is a button in the center of the vertical position knob that puts both inputs to zero. Depress this button and set the trace to a reference line position.*Select DC coupling on the +input for the input probe.*Set the comparator voltage control to zero.*Select Vc for the -input.*Connect the probe to the power supply output. This should cause the trace to move to the power supply output voltage.*Adjust the reference voltage control (+/- switch to + for positive volts to be measured) to offset the trace back to the reference line position.*Increase the vertical sensitivity per division using the volts/div knob.*Adjust the reference voltage control to offset the input's test voltage to a high a sensitivity as required.*Further 10X magnification can be had by pulling on the red center knob of the volts/div switch. Doing this increased the voltage comparator volts by 10X. There is a mechanical stop at 10mV when the red knob is pulled.The voltage reference display decimal point will move/scale depending on the volts/div setting and if the red center knob is pulled out.*If the noise becomes excessive apply the 5Mhz BW limiter.*When the desired sensitivity and display configuration is reached, the small changes in power supply voltage and it's regulation response will be easily visible along with all the stuff living on the power supply's output.*If the power mains is on a variac, wiggle the power mains voltage up/down to see how well it regulates line-load.Why all this instead of simple using AC coupling at the input, using the 7A13's voltage comparator feature is allows precision measurements of power supply regulation, noise and related. This is the same measurement capability as the LeCroy-Teledyne-Preamble 1855 diff amplifier add on at a small fraction of it's cost. The 7A2s is capable of this same test without the precision voltage reference.There is a test request.Would it be possible to connect one of the 7A13's input to the input of the Rigol's input to look for A/D switching and related digital switching noise coming out of the DSO's input?BerniceQuote from: miguelvp on April 05, 2015, 08:53:48 am

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 06:36:46 am
content: That worked a treat, so as long as my UNI-T is calibrated right I have the 7A13 agreeing with it, the HP E3615A is out of cal according to the Rigol and the UNI-T so I should calibrate it one of these days.Quote from: Rupunzell on April 06, 2015, 04:59:14 amDo I have to terminate them both? at the moment I can only find a single 50 Ohm terminator.But if not I see nothing if I connect both inputs together with a 4ft coax, what am I expected to see? and do I have to do anything else other than just hooking both up together?

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 06, 2015, 07:03:20 am
content: How much "stuff" was found on that power supply under test and how good was it's regulation?This why the LeCroy-Teledyne_Premable diff amplifier add on is made today, for test like this. To think having this identical test capability for $20 USD? not too bad eh..There are a LOT more test that can be done with the 7A13. Do make up a set of matched probes for it. The probes will need to be attenuation matched and frequency response matched and probe length matched. The goal is to preserve as much of the common mode performance at the 7A13's input connectors? Once the matched set of probes are found (shorter probe cable length is better if possible), make up a equal length of sizable copper braid for a ground strap with a banana plug on one end and a nice stout copper clip on the other end. Tie wrap all three together as a single bundle with the smallest grouping that fits at the 7A13 input connectors and the smallest reasonable grouping (about 6" probe spread or less if possible) at the probe end. This is done to help reduce field pick up and help preserve CMMR. Clip the ground strap to the DUT chassis ground and/or tie the probe ground leads together or keep them separate depending on what is needed for a specific test set up. Compensate each probe individually, then tie the probes together and drive them common mode. Tweak one of the probes to balance out CMMR as much as reasonable, It will never be ideal, but can be quite good.No 50 ohm termination initially for that test. If switch noise or etc is found, then try adding the 50 ohm termination to see if there is any difference. Run the volts/div to 1mV at full BW if needed or possible.Use a short a BNC cable as possible. Low capacitance matters here. Ideally, a much wider BW analog scope would be used with a FET probe to the DSO's input. Roll the input attenuator controls up/down and repeat with the other panel control to see if all that makes any difference.BerniceQuote from: miguelvp on April 06, 2015, 06:36:46 am

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 08:09:05 am
content: Quote from: Rupunzell on April 06, 2015, 07:03:20 amThe regulation was good, but the power supply displayed output was and has been off. I did rely on my DMM for accuracy.I kind of didn't follow the instructions to the letter.I did trim the voltage gain in the 7A13 to match what the DMM was reading, but once I did that, it tracked the power from 4 V to 0.01V just fine.The Comparison Voltage higher digit rolls back on the higher digit but I just ensured that both knobs were at their full counterclockwise position.Quote from: Rupunzell on April 06, 2015, 07:03:20 amI do have extra probes around and I always get them in pairs. I also have some old tek probes but not sure if I'll find two alike in my bag. As for copper braid I do have desoldering braid but I'm running short of it, maybe I should pick up more. But one thing what is CMRR used for in practicality? I guess I can look it up but it's late now so by the time you reply I might have read about it.Quote from: Rupunzell on April 06, 2015, 07:03:20 amI do have a FET probe (7A11 but unsured of it's calibration, even if it has a green round sticker over a Rejected sticker with reason: Balance DC Noise Problem, dated 11/12/93), it's the middle module on the cleaned up 7613 scope. But it's late so it must wait.Tomorrow back to work so I'm not sure how much time I'll have to check this.

author: edavid
author_rank: Super Contributor
timestamp: April 06, 2015, 03:39:59 pm
content: Quote from: miguelvp on April 06, 2015, 04:34:15 amYou should keep the 7613 if you think you might get a curve tracer (7CT1N or external) or a spectrum analyzer w/o storage (7L12 or 7L13)... the analog storage is very helpful for that kind of low rep rate display.Get another 7603 for the hackerspace

author: paulie
author_rank: Frequent Contributor
timestamp: April 06, 2015, 06:36:51 pm
content: Quote from: KJDS on April 05, 2015, 09:03:29 amLOL This gives new meaning to the term "hijack". Not only has OP failed to respond in this thread but probably soured on the forum as a whole. Well done dudes.

author: miguelvp
author_rank: Super Contributor
timestamp: April 06, 2015, 07:15:52 pm
content: last active tomorrowHe got his answer and probably made his mind, as for the merits of Analog vs Digital, what is so wrong talking about it since it relates to the OP's question.So if he was only going to look at:QuoteWhat device is better? He might never have the need for the extra capabilities of a DSOAnd I'm learning as well to appreciate the Analogs that I usually put aside.

author: Rupunzell
author_rank: Frequent Contributor
timestamp: April 07, 2015, 04:10:36 am
content: The reference voltage control knob is not too difficult to use, intuitive and quite accurate. Inside of that assembly lives a bunch of matched 0.1% or better resistors with very low TC. To keep things accurate there is high precision and temperature compensated zener diode. The stability and accuracy of this internal VR will surprise many who delve into it.Take the side cover off to reveal the gold plated pc boards with every active device on high reliability sockets and every component is designed to be serviceable. The input source follower's gate pin is soldered to a teflon standoff to keep that node away from stray currents in the pc board. This is how the 7A13 can achieve very, very low input bias currents. The inputs are voltage clamped with a extremely low leakage diode to limit damage to the input FET from input over drive.This level of quality design and construction and attention to detail is not practiced often at all today's world of disposable techno widgets.Here is what a set of differential probes looks like using hewlett packard miniature probes. This is a x1 set about 1 meter long. x1 probes only require matching attenuation (measure the resistance from probe tip to BNC connector for match) and equal length and manufacture model. x10 probes require matching more parameters and they must be adjusted to achieve proper common mode rejection at HF. Tradeoff, the x1 set has much higher loading with increasing frequency as there is no lead-lag network to aid in reducing probe tip capacitance. For the x10, loading is less with increasing frequency trading off lower common mode rejection (CMMR or CMR) due to the difficulty with keeping the probes and probe assembly matched.The ground braid is about 1/2" wide copper with a banana plug soldered on the 7A13/7A22 end with the hefty clip on the other end. This ground strap must be hefty. Solder wick will not do, that is WAY too small and thin. The probe grounds can be tied together as shown here and the Ground strap tied to the DUT chassis ground.An alternative is to leave the probe grounds off using the common mode rejection ability of the diff amp (7A13/7A22) to sort out the common mode noise and mess. This tends to subject the diff amp to more difficulties, but can work better under some test conditions.The FET probe would be better as it would reduce the loading on what could be HF noise and etc coming out of the DSO's input connector. If the FET probe has DC offset problems, it is often due to the input FET at the probe tip getting zapped by the previous user. This is a very common problem with active probes as the input device is quite fragile and can be damages easily. Quick check is to put a DVM on the FET probe tip and probe ground shell to check for DC. If the FET's gate has been damaged significantly, there will be some DC present at the probe tip (Gate pin of the FET).For now, the easies and simplest test is to connect the two together with the shortest possible coax and go looking for switching and other HF transients and noise.BerniceQuote from: miguelvp on April 06, 2015, 08:09:05 am

author: GK
author_rank: Super Contributor
timestamp: April 08, 2015, 02:13:03 am
content: Quote from: Rupunzell on April 06, 2015, 03:48:09 amI was replying to a question about my 1940's Philips oscilloscope.

author: aargee
author_rank: Frequent Contributor
timestamp: April 08, 2015, 08:08:18 am
content: I imagine poor Mike_mike has no idea where his thread went.

author: Mike60
author_rank: Contributor
timestamp: April 19, 2016, 08:44:57 am
content: HiWhat you are think about :DSO-201http://www.sainsmart.com/sainsmart-arm-nano-dso201-oscilloscope-mini-storage-digital-pocket-sized-portable-kit.htmlI need for low frequency, DC/AC. I am sure i will not work with RF or audio signal.I need to test output voltage from OLD plating rectifiers who are working on 3phase.It is very nice for my work - build in battery ( portable ).Thank you in advanceMike

author: tautech
author_rank: Super Contributor
timestamp: April 19, 2016, 08:53:34 am
content: Expected voltages?I'd be worried about YOUR safety.What do you need a scope to display?Won't a DMM do what you need?

author: Fungus
author_rank: Super Contributor
timestamp: April 19, 2016, 09:49:24 am
content: Quote from: tautech on April 19, 2016, 08:53:34 am^^ Whathesaid - why do you need a 'scope for that?A true RMS multimeter would be the correct tool for the job.

author: JPortici
author_rank: Super Contributor
timestamp: April 19, 2016, 10:06:59 am
content: Meanwhile, on april 1st the OP grabbed a sack of popcorn

author: Mike60
author_rank: Contributor
timestamp: April 19, 2016, 01:13:21 pm
content: I have TRMS meter but it is better & easier to show to my boss if one of this 3 phase are bad. 3phase on low voltage.rectifiers for plating are no more like 20V/2000A. We have some new rectifiers but are switched electronically. So I don't need for them.The are filled with plenty of diod and 3phase secondary transformater. To test if one low voltage phase are bad it is easier with graph.Old factorySo - please.It is better DSO201 or DSO202 for what I am asking or NO ? I suppose I can save the graph and show him.Best RegardsMike

author: Fungus
author_rank: Super Contributor
timestamp: April 19, 2016, 02:15:58 pm
content: If you want to look at phases then you really need two channels.There's no way I'd recommend one for general EE work. The user interface on those things is awful, but... if you only want to use it with one type of signal you can set it up once and leave it.The inputs are rated for 80V so in theory you'll be OK on a 20V tri-phase supply. OTOH I assume there might be something wrong with your supplies otherwise you wouldn't be looking at them. Anything with windings and inductors can producebigvoltage spikes. I'd hack together a 10x resistor divider and connect the probes to that instead of connecting them directly to the power supply. Maybe even add a 10V Zener diode to clamp the voltage to 10V after division.It's not perfect, but for your application, and for something the boss can look at, then ... why not?

author: Mike60
author_rank: Contributor
timestamp: April 19, 2016, 03:09:08 pm
content: Every time he told me power / voltage are not correct.BUT - all the time he see chemicals are wrong. Who make chemicals every time he makes mistake and I want to be OUT from this circuitIf i show him i have all 3phase then he stay calmI will post some pictures with our OLD rectifiersI spoke with him to buy new but ....I found on Aliexpress for 1000$ with delivery. He can buy from here with ~ 8000£He don't have trust in China but all ours rectifiers are made in ChinaRegardsMikePS. This oscilloscope i will buy with my £ so ar my propertyI play with oscilloscopes plenty of years ago ..... LONG TIME AGO. I am not so young. So this new are like gadget for me

author: oldway
author_rank: Super Contributor
timestamp: April 19, 2016, 04:42:09 pm
content: I also worked on these old rectifiers for electrolysis.It was a 20V rectifier 12.000A I changed into 2 units of 20V 6000A by adding a new control.Primaries were controlled by thyristors. (There were 2 transformers)The secondaries and the diodes were watercooled.What you need is an ac/dc current clamp.This allows to check the current balance in the phases and in the diodes.I would choose an analog scope as Tektronix 2235.It is relatively light weight and easy to carry.

author: Mike60
author_rank: Contributor
timestamp: April 19, 2016, 06:49:14 pm
content: We have clamp-meters but i don't like and I can not see if one phase are down.No space rear and on both sides to open and measure inside.If I have final voltage on buss bars like attachment I am sure all 3 phases are working properly.All rectifiers are only with diode air-cooling. Only one smaller has water-cooling. There are manual with mechanical control. Maximum amperage for this are 2000A / 15V.I make many electrical changes from old non-working analog meters to digital to be accurate and better visible.So I don't need some more expensive device to buy for this job.What I invest in this oscilloscope are from my pocket.RegardsMike

author: Fungus
author_rank: Super Contributor
timestamp: April 19, 2016, 07:22:00 pm
content: Quote from: Mike60 on April 19, 2016, 06:49:14 pmYou have very clear requirements and this will do the job. I say go for it.

author: oldway
author_rank: Super Contributor
timestamp: April 20, 2016, 07:08:54 am
content: Old rectifier, but I did not mean that old

author: Mike60
author_rank: Contributor
timestamp: April 20, 2016, 07:20:21 pm
content: Your rectifier are build LAST YEARMy, 40 years old or moreMike

author: oldway
author_rank: Super Contributor
timestamp: April 20, 2016, 07:56:25 pm
content: Quote from: Mike60 on April 20, 2016, 07:20:21 pmI made this change in 1993 on a rectifier which already dates back more than a decadeI split the 12.000 A rectifier in two 6.000A rectifiers.On picture rectifier1, you can see lefthand the old control and righthand the new one.From top to bottom:(new primary phase control)3 x ultra fast fuses for thyristor's protection and 3 fuses of the transient filter3 x 100/1A current transformers and transients filterFull controlled bridge (6 SCR's) 120A3 x auxiliary transformers and fusesnew three-phase control circuit.watercooled diodes

author: IconicPCB
author_rank: Super Contributor
timestamp: April 20, 2016, 08:16:28 pm
content: Mike get three CTs and monitor rectifier input currents.Use lamps in parallel with CT load resistors for immediate visual comparison.Inexpensive and self powered.I made my own hot and cold press with three phase heating cal-rods and settled on a current transformer bi-color LEDS for ON OFF indication

author: Mike60
author_rank: Contributor
timestamp: April 21, 2016, 09:33:45 am
content: HiI need to write about this on another topic with different testing devices not here on " Oscilloscope " ?Moderator can move what are not for Oscilloscopes ?" oldway"You have plenty of amperage with this rectifiers. We don't have and don't need.But Yours are new comparing with mine.Like I write above.I don't have space to take down lateral or rear wall and work inside rectifier.So I can not install nothing inside. I need only outside to do something. If i see output DC-graph i am sure are ok.I have some cheap and perfect working displays from Ali... but are for AC. I have and for DC but i need to install shunt.What I install are with very low cost. China but working.Another picture with one new rectifier on top on older ( not working anymore - input primary transformer short ) rectifier. Same capacity & power.If I will buy one small oscilloscope i will play with him and home when i have free time from my wifeRegardsMike