EEVblog #86 - Page 1
Forum section: electronics / general

author: orbiter
author_rank: Frequent Contributor
timestamp: May 11, 2010, 11:40:15 am
content: Hey Dave, why not test that DSO Nano you love so much in your video? You know you want toj/kPlus I want to see it taken apart.PS.. I lol'd at the end of the clip where you were singingregardsorb

author: EEVblog
author_rank: Unknown
timestamp: May 11, 2010, 12:30:07 pm
content: If they want to send me one I'll happily slag it off!Dave.

author: Ferroto
author_rank: Frequent Contributor
timestamp: May 11, 2010, 04:29:14 pm
content: Since were on the topic of hand held scopes fluke has one of there own.http://us.fluke.com/fluke/usen/products/CategoryOSCILL?trck=scopemeterProbably worth a look, although I'd prefer a bench oscilloscope for ease of use.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 11, 2010, 04:35:52 pm
content: Well I just took a look on ebay in the EU.And found not that friendly prices about them.Even for the old ones .I am not aware if it worths to buy a damaged one and repair it some how.It looks to be many damaged ones at low prices, what possibly can damage one oscilloscope,would be my next question..

author: orbiter
author_rank: Frequent Contributor
timestamp: May 11, 2010, 05:14:37 pm
content: Quote from: Kiriakos-GR on May 11, 2010, 04:35:52 pmHow about this one Kiriakos my friend? Was even thinking of bidding for this myself...http://cgi.ebay.co.uk/Tektronix-100MHz-Oscilloscope-model-2235-/140406085058?cmd=ViewItem&pt=UK_BOI_Electrical_Test_Measurement_Equipment_ET&hash=item20b0dad5c2

author: Simon
author_rank: Unknown
timestamp: May 11, 2010, 06:41:59 pm
content: thats a very good buy but I think it may eek towards £ 200 at the last minute

author: hans
author_rank: Super Contributor
timestamp: May 11, 2010, 07:23:56 pm
content: I agree with you on the analog and digital ease of use. Personally I find a digital USB scope isharderto use than an old analog one. You really can't beat some knobs and buttons against graphs, toolbars, etc.I have used Analog, Digital and USB scopes on college before and personally I don't notice much difference between digital and analog one. Analog is even better in some ways, because digital tends to drag you down to a ton of menu's to unset things that the previous student has set up. You don't want that if you just want to measure something quickly..Now I also used an USb scope on 1 occassion before for measuring a step response of some system. It has like a 300ms step response transition, which you could measure with a digital or analog one with the cursor, but I thought it lacked inaccuracy (more crucially the models we used: memory, couldn't walk futher back than 250ms on the 10ms scale). So , I happened to know my college hada handyscope. We had to 50MS/s one, which is quite expensive (1050 euro's is more like $1350 or even 1500 aus $) and has a bunch of functionalities (including AWG built in, which works to quite high performance as well). I don't know how the input protection is, we don't do ripping apart on college, but I believe they aren't like crappy devices at all.Works quite nicely, plug in, get the software and off you go. Software was reasonably quick to learn if you know where to look and have experience with scopes. Got a excel data sample (CSV file) quite quickly with like 10k samples per second of the step response after just 30 minutes of fiddling. That wasvery veryaccurate, and very fast. I did like 20 samples (different responses) in like 15 minutes. That would otherwise have taken me a complete afternoon, with nearly as much accuracy. A digital scope could do this as well I think, but as these are designed for doing these kind of measurements, it was ideal.Sounds good, but I want to add something crucial that is lacking with USB oscilloscopes. One is, you have to know exactly what you are doing when you use one of theses. You don't want to do something like mess up the grounds or something, otherwise your PC that is measuring WILL have a problem too. Now that's not even the biggest issue. The biggest issue is that you need the PC. A normal scope is something you can just pick up and measure anything without the need of taking a laptop with you. Now an analog scope is heavier than a laptop (and bigger), but it measures right away, not after booting for 3 minutes. That's my biggest issue. You always need the computer, which is already very full of designs, datasheets, internet, media, mail, etc. that's open all the time.

author: Simon
author_rank: Unknown
timestamp: May 11, 2010, 07:32:32 pm
content: when at school I found the digital scopes (CRT versions) a nightmare and never used them. I was quite happy with an analogue scope and to be honest if your trying to use a scope properly instead of hitting the auto button then a digital one will be more baffling if you do not have a good foundation of using analogue scopes. I wish I had kept my analogue scope but had to sell it to part pay for the Rigol DS1052E

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 11, 2010, 10:27:21 pm
content: Quote from: orbiter on May 11, 2010, 05:14:37 pmI was looking for something compact like 60MHz dual .. but I am not willing to spent any serious amount of money so to get one, simply because I do not do any projects that needs it.And even if I was getting one , I would probably use it, to just check for ripple in DC power supply's .

author: saturation
author_rank: Super Contributor
timestamp: May 12, 2010, 03:28:25 pm
content: While I think analog scopes are better general purpose ones, I don't think a newbie should just pellmell jump into getting one without knowing some caveats Dave did not make apparent.http://electronicdesign.com/article/communications/does-anyone-still-use-an-analog-oscilloscope-14793.aspxMany old devices use alotelectrolytics caps that are at most, rated for 20-30 years. If you get such a device, particularly a scope, its likely due to fail very soon, and every day it works is a blessing. Those caps would fail sooner if the scope was used in extremes of its operating temp, such as in the winter colds or summer heat, if taken as a field instrument. Also, how much abuse has the inputs already taken? and was a scope 'stored' because it wasn't useful anymore or it stopped working?Tektronics built in the 1990s and up, are increasingly difficult to repair and use specialized parts, while older ones use more 'generic' technology but are very likely to fail from sheer age.A quick review of eBay shows many such scopes are sold AS-IS, and there is no way to ascertain it will even power up, nor that it even works near to spec. Those that are refurbished are a better bet, but they are going for $300-400 to start, because the seller has gotten it back up to snuff, in which case you're getting mightly close to a Rigol 1052E.So, I can see a seasoned hobbyist getting one knowing a repair is likely in order, but a newbie will likely be less served by getting one.If you inherit a scope from a good user, or a school, it at least can be examined, and the donor may likely know something about how it works and its caveats. And free is free.That said, if a newbie is just getting his feet wet in electronics, a DSO nano isn't such a bad bet, given it should work out of the box, and can show them what a basic wave form looks like.Also, a lot of folks I read here discussing equipment that can easily resolve 1MHz and up, postly elsewhere about design issues that are barely cogent for competent audio frequencies design, that I just can't see what all this extra bandwidth is going to do for someone who is challenged by Horowitz and Hill.Don't turn off a newbie by making the barrier for entry into the hobby high. If they outgrow the DSO nano, then good, but I feel a newbie will learn electronics by exploring the limits of their gear. $300 reserved for a good scope, used or new, can be used to furnish almost an entire learning lab given the cost of basic lab equipment from China: DMM, evaluation board, power supply, a cheapie scope, signal generator etc.,

author: charliex
author_rank: Frequent Contributor
timestamp: May 12, 2010, 04:37:05 pm
content: Analogue scopes just look cooler too, I like my digital Tek TD but there's nothing quite like a bright CRT trace with a lot of fancy dials and stuff to geek out on. Playing starwars on the XY mode works a lot better too!I like the little fpga4fun scope toy, but only as something interesting to build like the xmas tree lights from velleman etc. There's also the problem of isolation and so on. I have a spare fpga4fun flashy, i'll send you that for a review dave even though i already know what it'd bebut featurewise it'd get beat by a soundcard scope. honestly, it'd get beat by an etch a sketch and a half dozen cups of coffee.Wouldn't mind seeing you review a picoscope though, they're fairly popular in automotive but thats because they provide a lot of comparison wave forms and tools designed for automotive diagnostic, and lots of people have them. I tried one out and wasn't into it all, the software was pretty poor, but its like apple stuff, its simplistic and works in its specific area for specific people. My curiosity piqued when I saw the software could do a compression test.

author: Simon
author_rank: Unknown
timestamp: May 12, 2010, 05:22:50 pm
content: how do you play starwars on a scope ?

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 12, 2010, 09:32:52 pm
content: Quote from: Simon on May 12, 2010, 05:22:50 pmLOL ..I had a conversation today with some friends electronic engineers ,they told me the same stories about oscilloscope age , dying from age screens ,limited support about parts etc etc ...And they advised me to go for a Hameg , German build, reliable ones , and there is parts for them and good support even today.

author: saturation
author_rank: Super Contributor
timestamp: May 13, 2010, 12:01:22 am
content: Hameg models are very good scopes. CRT are quite reliable, so a most common issue is the deterioration of the discrete capacitors in its boards, especially the electrolytics. I know CRT phosphors fade with age and use, but its hard to say how much life is left in a CRT.http://www.hameg.com/446.0.html?L=0HQuote from: Kiriakos-GR on May 12, 2010, 09:32:52 pm

author: charliex
author_rank: Frequent Contributor
timestamp: May 13, 2010, 12:55:36 am
content: Quote from: Simon on May 12, 2010, 05:22:50 pmI used to be an electronics repair tech at funland in blackpool, the XY boards on the old vector starwars machines would break a lot, so we used to check the game logic was working by connecting it to a XY scope, even better if it had a blanking input since then it was basically exactly the same look, just on a small screen. Works for any true vector based game.this one

author: EEVblog
author_rank: Unknown
timestamp: May 13, 2010, 01:33:26 am
content: Quote from: saturation on May 12, 2010, 03:28:25 pmI still maintain that $80 spent on the DSO nano is pretty much money down the drain on a toy.Aside from the obvious caveats about buying old second hand gear, the basic fact that for the same $80 you can get say a proper 20MHz dual channel analog oscilloscope that (provided it still works) will still be a useful and valuable tool in a few years time. The Nano almost certainly won't be.And then there is the old adage that you learn the most when your you have to troubleshoot things and figure out what's going on. If for example you buy an old second hand scope and one channel starts playing up, the skills learned bya) recognising that's it's playing upand b) investigating it and possibly fixing itcan be invaluable.No such luck with the toy Nano out of the box that won't even teach you much about how an oscilloscope actually functions.But hey, if the Nano floats your boat, then go for it.And like I've said before, I hope your next project DOESN'T work!Dave.

author: Unknown
author_rank: Unknown
timestamp: May 13, 2010, 08:25:18 am
content: I guess the DSO nano appeals to people because it has more sex-appeal than an old CRT scope, especially for people used to modern electronics like ipods. This is one thing they got right compared to most DIY projects. Plus it takes up very little space (the reason why I don't have an analog scope, although I've got an excellent DSO so I don't really need it). But I agree that it's absolutely useless as a scope.It's true that troubleshooting is very educative (especially since some of the older scopes from companies like HP and Tek have excellent documentation). An issue with learning troubleshooting on a scope, however, is that you (often) need a scope to fix a scope. No big deal if one of the vertical amplifiers dies, but you're screwed if it's the horizontal circuit or the power supply.

author: tecman
author_rank: Frequent Contributor
timestamp: May 13, 2010, 05:30:23 pm
content: Dave:I would disagree with you. I have plenty of scopes in my lab, from the ultra transportable TEK 547 on to my new Rigol 100 Mhz 1052. BTW the 547 is still the finest analog scope that I have ever used. A bit temperamental at times with the old tubes, but when it is up and calibrated, nothing beats it. Anyway I have a TEK 214 and a Fluke Scopemeter that I use for "away from home" needs. Both work great. But I got a NANO just because it was cute. Very limited, I agree, but show me something that I can literally slip in my pocket and take a few readings if needed. Granted most of my professional work is under 500 Hz, so bandwidth is not an issue, but on the off chance I need to see something, it is certainly not a toy. No I would not recommend it to anyone as a first or only scope, but for the convenience and the price, tough to beat.paul

author: Simon
author_rank: Unknown
timestamp: May 13, 2010, 06:19:04 pm
content: as a first scope you need something reliable that can cover anything. Personally I find the Rigol small enough to tow around with me. if you want the gadget and know exactly what limited use you are using it for sure get the nano but this is all about beginners first scopes !

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 13, 2010, 06:45:08 pm
content: Quote from: Simon on May 13, 2010, 06:19:04 pmThats true , the professionals who does repairs , does not need any scopes at all.There no any more available, schematics with test points of oscilloscope curves, in them.

author: Simon
author_rank: Unknown
timestamp: May 14, 2010, 06:47:55 am
content: Quote from: Kiriakos-GR on May 13, 2010, 06:45:08 pmNo because they expect you to dump the unit and buy another one

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: May 14, 2010, 01:34:48 pm
content: Quote from: Simon on May 14, 2010, 06:47:55 amI agree , but they had win, mostly by not offering parts.Thats why I am avoiding of getting any goods , who follows the same philosophy .And yes, my choices are narrowed by allot, but at list I support the ones who worths to be supported.

author: Simon
author_rank: Unknown
timestamp: May 14, 2010, 06:16:23 pm
content: I no longer buy cd players because they have a failure time of a year or less, I'm pretty certain that the laser head is specifically chosen of low quality so that it fails, becuase this one part fails a completely usable machine is dumped !In our house our main CD player is an old PC CDROM drive that is powered from an old power supply and runs through my dads main amp which is older than me and still works (which is no surprise as it was made when stuff was made to be bullet proof)

author: slburris
author_rank: Frequent Contributor
timestamp: May 14, 2010, 07:00:30 pm
content: I can't believe that people are arguing that you should get a DSO first or insteadof an analog scope.Unless you spend your days looking at sine waves, you need at least 10Xoversampling over your frequency of interest to accurately reproduce thewaveform. Why? Because anything except for sine waves contain higherorder harmonics.And don't tell me that you just use "equivalent time sampling" to build upthe waveform. That only works if the waveform is repetitively stable.How do you know it is? Isn't that part of the reason you are lookingat it with a scope in the first place?I've had jittery signals that look confusing on a DSO, but puttingthem on an analog scope made the issue much clearer.Don't get me wrong, I love my DS1052E, especially since it's nowacting like the 100Mhz model, but it's just another tool in my toolbox.It adds to but doesn't replace my Tektronix analog scopes or logicanalyzers.The DSO nano is really cute, but except maybe for audio circuits, Ican't think of anything I do which will fit in its bandwidth restrictions.When I was a beginner, I couldn't afford a scope at all, so I startedout with a Radio Shack logic probe. It's amazing what you can debugjust seeing if a signal changed or not, but you have to think.I learned more about how things worked with that little probe (which Istill have 30 years later) then I would have learned had I justpushed an auto button on a DSO.One guy's opinion, anyway.Scott

author: adam1213
author_rank: Regular Contributor
timestamp: June 10, 2010, 02:53:32 pm
content: In terms of a general purpose oscilloscope I agree that the DSO nano isn't the best choice. However the DSO nano does have other features if you are interested in developing software for its hardware (such as having a nice colour screen) You could even write a game for it. (so what if its a toy - as long as you realise its limits)- I was thinking of adding some features to it (eg RMS voltage) - all of which require learning how an oscilloscope actually calculates things.- I appreciate that the code for the DSO nano is available (well at least until one of the newer version) However the C code for the DSO nano is terrible. The code has lots of global variables with one letter names and a uses arrays where it should be using structs)

author: charliex
author_rank: Frequent Contributor
timestamp: June 10, 2010, 03:43:48 pm
content: i looked through the 2.31 code, doesn't look that bad, nice short formatted functions, separated into file groups. I was quite surprised expected it to be a lot worse.there were quite a lot of commented out code/functions but that sometimes can be ok, not too neat but quite forgiveable for an evolving product.its ok thats its a a toy, but its not sold as a toy. like the fpga4fun scope is good for getting your feet wet with fpga's but its not expected to actually be used as a scope, then its limited on where you can go with it after that, which is both good in the way its simple, and bad that by simple its more limited than a typical fpga dev board.

author: adam1213
author_rank: Regular Contributor
timestamp: June 10, 2010, 11:48:06 pm
content: I personally like very high quality code (with lots of abstraction) and about 100 lines per file.- the dso nanos main function is over 500 lines long.The reason I am unhappy about the code quality is that bad variable names with global variables not only make the code hard to change but make it very easy to make mistakes.For example moving the trigger down will cause the software to crash / move the trigger passed the headings.if((Key_Buffer==KEYCODE_DOWN)&&(Item_Index>(MIN_Y+5+Item_Index))){// other codeItem_Index--;}

author: charliex
author_rank: Frequent Contributor
timestamp: June 12, 2010, 12:58:21 am
content: Personal preference I guess, 500 is the upper limits but its not terrible, abstraction doesn't seem terribly useful for the dso nano though its a good thing to do in moderation. 100 lines per file would annoy the hell out of me and slow down our compile times like crazy, and it'd be a pain to deal with the source control, so it seems excessive to me. i don't see the gain about having to load a new file everytime i want to look at another 100 lines of code, I typically group them into what the function does, by file, and split them into sub groups if they're getting out of hand. but for a project of 500,000 lines of code, you're suggesting 5,000 files ?I don't see the problem with the globals, its single threaded and no OS, they're often faster and less code/space, often the same for arrays vs structures, but the proper thing to do is check if its important and what the end result looks like, or even if it matters.Compared to some of the code i've seen come out of OS projects, or ones like this, it ranks reasonably high. It's fairly easy to read through.Again personal prefs on short variable names, people prove and disprove the usefulness of things like hungarian notation, i'm a believer in that code out to be readable and understandable with short variable names, if the variable needs to describe what it is, doing, then the code is either overly complex or poorly documented.I'm sure if you futz around with the code you'll find a million ways to break it, as few asserts here and there wouldn't hurt, but i don't know what the code/data space is like on it, so i can't really comment conclusively about that.

author: adam1213
author_rank: Regular Contributor
timestamp: June 12, 2010, 01:22:17 pm
content: in my opinion if comments are needed to describe the code then the code could often be written better.- if the variable names describe what the code is doing so that you don't need comments then you have done well.- the advantage of having only 100 lines is that you don't have to scroll up and down the file - it fits on one screen. If the file contains a collection of related tasks then you don't have to keep going between files to look at related things.- also it may speed up compile times (as you only have to compile the files that have changed and then link them together)Can you please give some examples of projects with 500,000 lines of code.- anyway I 5,000 files doesn't sound too bad provided they are put in sub folders (as opposed to a 500,000 line file)- I know xilinx ISE is very big (~5 gb) in my opinion its because they duplicated code and programs (the installer for 11.1 installs two copies of gcc and java)

author: charliex
author_rank: Frequent Contributor
timestamp: June 12, 2010, 09:48:11 pm
content: There's a difference between people who just auto comment for the sake of it, when the code's perfectly readable and using a typical function header that is parsed with say doxygen, or specific comments that note something thats unusual, or may have an unintended consequence. Generally programmers who don't write function type documentation get too busy to sit down and write proper documents, so it never gets done. A lot of people give out libraries/api's and not source code so its very useful to have well documented code that can be parsed. Its a nice structure.There are varying arguments on each side of using expressive variable names to describe what something does, i follow the answer you gave about comments since effectively its the same thing, you say if it needs commentary it probably needs to be written better, of course that entirely misses the part about autodocumenting, then the same goes for variables, if the variables need to be explictly written out as what they are, then it could be better code.This is a general statement, and not a specific one, so there are of course individual cases where extensive variable name is needed, some programmers do write good documentation and get the time to write code then properly document, or have departments that do it. But doing it as you go along means you remember more about the process, you can get people using it earlier and so on. Its a good habit to get into.100 lines of code isn't hard to work through, there isn't a lot of difference in an editor from clicking a scroll bar, to opening a file, usually the latter is a longer process and can take up valuable desktop space, which is better suited for looking at code etc.You're not serious about asking about a project with 500Kloc of code right ? Even it it was a 10Kloc program, it'd still be an excessive amount of files. Sure precompiled headers help but compilers are faster at compiling one file with a few functions, vs two files with one function.Then you've got all the hassles of source control, merging etc. Its potential for a just a huge mess, for a very small return in my view, not scrolling down a page or two ?

author: Fezder
author_rank: Regular Contributor
timestamp: June 12, 2013, 02:56:19 pm
content: First, sorry about reviving ''dead'' topic, but, slap me in the case of being dumbass...I'we personally gotten now total of 6 CRT scopes for free, well, 3 are broken, different faults, but i dont discuss about it here, they have their own place. But, i remember first one wich i got, it was supposed to be easy to use, 10mhz/2 channel. Nothing big, my first thought was oh crap, its broken, gotta change it next day. THEN i just saw, density was off, and ray's position was off screen, no wonder nothing showed up!. And, teacher was right, its pretty darn hard to destroy these things, well, its possible yes, to kill yourself with these but you get my point. I messed around with this 10mhz version long time, got used to it like my DMM.When i helped at school, testing other scopes, many different models, all have same basic idea and ''operating system'' so to say it, pretty easy to use many, or all, once been using one for long time.Now that i have 150mhz/4chan models, i had to learn again using, theyre pretty different than 2chan models, but now, they are pretty easy to use, well, couple things are still mystery.Sorry if this post was pointless, just had to say this, dave's video reminded, my starting position was exactly this poor-student-amateur, which doesn't have 300 dollars to spend on scope, no way!. I never used digital scopes even yet nowadays, but i wish someday i have one.