Oscilloscopes For Modern Engineers? 337
Every few years someone asks this community for advice on oscilloscopes. Reader dawning writes "I've just graduated with a degree in Computer Engineering (and did a Comp Sci one while I was at it) and I'm finding myself woefully under-equipped to do some great hardware projects. I'm in major need of a good oscilloscope. I'm willing to put down $2,000 for a decent one, but there are several options and they all seem so archaic and limited. I'm happy to use something that must be controlled through a PC if that gives me more measuring features. What would you, my esteemed Slashdot colleagues, get for yourself?"
An old Tektronix is fine for a modern engineer (Score:4, Interesting)
Re:An old Tektronix is fine for a modern engineer (Score:4, Informative)
A new Tektronix oscilloscope will work as well. When I was an undergrad my colleagues were convinced that you need analog ones to make proper measurements, but I've had great success using digital ones. I actually prefer them.
Without a definition of what "good" means or what your needs are, I don't think that anyone can give you any sort of advice. I personally would never use one that had to be controlled through a PC. Having to drag a laptop or something all around the electronics of an experiment would be a major pain. (I've only used them in the context of the detector and apparatus signals in physics experiments.)
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I like the Tek 2430/2432/2440 scopes a lot, and used one for years in conjunction with a 2467, for those cases where analog-scope performance was needed. Apart from a few considerations like record length, this combination could easily stand up to any DSO costing less than several thousand dollars.
With the 2430-series scopes, the key points to watch out for are 1) make sure it passes its power-up self tests, as the CCD chips used for acquisition are no longer available; 2) avoid the original 2430s with no
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Just about everything Tektronix made was a thing of beauty.
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We have a Yokogawa DL-750 [yokogawa.com] at work. Thermocouples, Strain input, Voltage. Up to 1 Ghz sampling rate (on 1 channel). 40GB HD. Should be just under $40k :).
Spark fun [sparkfun.com] has quite a few inexpensive ones. They probably have everything else you need for your hardware projects too. Looks like it's a signal generator too. Or for 'on the go' stuff, this pocket one at SparkFun looks good.
Here's a generic one for $65 [virtualvillage.com]
Even the most basic ones at Tektronix start out at over $3k (that I was finding).
But it all depends on wh
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The more I use the modern digital scopes the more I hate them. yes they have many useful features like storage (although I did have an analog storage scope at a place I use to work) and the ability to make screen snaps and the like, but there is something about that analog phosphor glow that makes me all warm inside :-) and sampling sometimes has its issues !
Re:An old Tektronix is fine for a modern engineer (Score:5, Informative)
I work for Agilent. Trust me. They still call them scopes...
And for the original poster, be sure to check out how many waveform per second the scope can store. That is the reason that some people do NOT like digital scopes is that they first used a digital scope that cannot trigger and re-arm again in a reasonable period of time. Let's assume that you have a waveform that has an occasional glitch, but you can't set a trigger for it, so you have to catch it by chance. If your scope can capture 10,000 waveform per second, you stand a 10x greater chance than one that can only capture 1,000 waveforms per second. I believe that Agilent wins in this category.
Not really... (Score:5, Interesting)
I have a very nice, for me, rackmount 350MHz 4 channel Tek scope with some very killer plugins.
The scopes I used at work today are really beyond anything needed for home use, unless you're into some extremely expensive hobbies.
The portable scope is a 3054B; 500MHz x4 channels. (~$10k, with options) The good one is an 11GHz x2ch Lecroy ($ almost 6 digits), I made picosecond-order measurements with it today.
The differential probe was $5k each; (wasn't that what gov. spitzer paid? lol.) our newb has killed two. (4Vmax) $2k each to fix.
If you can afford it for home use, I'd recommend the Tek 3054 or a lower bandwidth cousin. They're very easy to use.
If you can get surplus scopes coming out of downsized companies, you can get a deal; that's how I got my rackmount and a stack of plugins for $130. It was a production fixture at a missle plant in the 90s. :)
Digital is great, as long as you realize the limitations; digital displays lie sometimes. If you're going to base a paper on it, use multiple measurements with different equipment. :) I've seen fresh engineers embarrassed by artifacts.
Re:An old Tektronix is fine for a modern engineer (Score:5, Insightful)
Ah, but you are likely working as an electrical engineer. This fine young man will most likely get a job in IT. My suggestion to him is to hold off on the hobby scope for a couple years. By that time, his soul should be crushed sufficiently that he gives up on ambition entirely and has no need for the device.
Re:An old Tektronix is fine for a modern engineer (Score:4, Informative)
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Despite the rather "textblock"ish formatting of the above post, I do believe that the Rigol DS1052E is one of the best entry-level choices right now, and is GREAT bang-for-the-buck. I have one and it has proven very useful. My only regret is that I purchased it before it got price-dropped to $400. (I paid around $530 plus New York State sales tax from Saelig.)
FYI, Rigol is the manufacturer of Agilent's entry-level units at this point.
To the article poster: You indicate you've done some looking and have
Heathkit of course, bitch! (Score:3, Funny)
As for your question, who the fuck knows?
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outsource it to india (Score:2, Funny)
have them take the measurements for you.
itll give you great experience in The Real World.
Kazkek (Score:5, Informative)
May I suggest you get a DAQ usb card and Labview from National Instruments. Probably some of the best investments you can do. You can do many things with a DAQ card and Labview including building your own digital Oscilloscope.
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While I'm a gigantic LabVIEW fanboy, those USB DAQs don't have the bandwidth of a real oscilloscope. IIRC, most of those USB ones sample at 50 - 500 kS/s. Your low end digital scope will have a bandwidth of 20 MHz or more.
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Bullshit!
Unless the OP uses LabVIEW at work or school (and is allowed to take a copy home to play with) it's a hell of a lot more money than a decent Tek o-scope. Daq cards are fine for some things but troubleshooting isn't one of them. Stay away from used HP scopes since the damn things never triggered right even when they were new.
Re:Kazkek (Score:5, Informative)
By all means, buy National Instruments hardware. It is fantastic. I have deployed it on a number of production systems that run for days and days and days without a glitch.
As for Labview, stay the fuck away from that steaming pile of dogshit. It is a great way to waste lots of time and give up your sanity (and possibly your anal virginity) unless you feel like fucking around at your lab bench and drag-n-dropping some blinky lights and text boxes to impress your PHB. Oh yeah, and it's also great if you enjoy having fresh-out-of-college, inexperienced National Instruments tech support fuckwads (i.e. never having done any actual work with data acquisition or signal processing in their lives) repeatedly tell you, "OMG, change the way you think! You're so wrapped up in the text-based language tunnel vision! LOL!" whenever you get frustrated because Labview actually slows you down and doesn't help you get your results.
Oh yeah, I almost forgot, it will also cost you an arm and a leg. A hardware and software (i.e. Labview) package will let you look at signals in the 10MHz range and above will probably run you at least $10-15k.
In my day to day work, I prefer to remain in the "text-based language tunnel vision." That is, I prefer to use a well-designed C or C++ API to write programs that actually work in a predictable and reliable manner. (The NI-DAQmx API is actually very powerful and easy to use.) That way, I don't have to scroll around in a blinding maze of brightly colored connector lines and boxes and stuff, just because some National Instruments fucktard decided that "text-based languages" are just too, like, texty and complicated and not very much fun, yay! Yuck.
Did you ever bother to learn properly? (Score:3, Informative)
I've been a LabVIEW programmer for close to 10 years. I have also been a C and C++ programmer for quite a long time now. I did large projects using both, sometimes using both in the same project. I can call myself a qualified programmer using both languages.
It is perfectly possible to create very large applications, using multi threading and proper design patterns. However, just like you had to spend years learning to write powerful and correct C++, you need quite some time to learn to program LabVIEW corre
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As someone who writes VHDL, Verilog, C++, and Matlab on a daily basis, I understand both
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In one of my previous jobs, I had the task of getting a test setup controlled by LabView working in our facility.
Tiny little differences in our setup completely broke LabView, and the "point, click, drool" GUI really insulated you from what was going wrong and how to fix it.
I was able to almost rewrite the whole damn thing in Perl, including adding new test instrument classes to Jeff Mock's long-unmaintained Perl GPIB modules, in less time than it took to try and fix that thing.
Even though Jeff's libraries
Re:Kazkek (Score:5, Informative)
And don't get me started on the fuckwads who recently tried to convert me to UML as a better way to do real-time programming. What a crock of shit dreamed up by computer theorists who've never actually run one of their programs.
dumpster diving (Score:2, Insightful)
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its funny that electronics engineers throw out their broken electronics.
Re:dumpster diving (Score:4, Interesting)
Not really.
If they need it accurate and traceable they'd have to pay a lab to calibrate it after it was fixed. Such a lab would reject it due to it being fixed (and charge a pretty penny with no calibrated scope at the end of the process.) So they're stuck.
(This reminds me of a story my wife tells about a lab PC that had a bad case of infant mortality. The local techs wanted to fix it themselves. She pointed out it was still in warranty - so the thing to do was send it back for fix-or-replace for free, rather than void the warranty and maybe end up with a broken machine and nothing (but wasted engineer time) to show for it.
Fixing a scope adequately for home use is another matter. Then, if you ever need serious accuracy, you can do the same sort of compensation hacks that were done back in the tube days, when stuff drifted all the time and you couldn't just have a lab tune up anything complicated and expect it to stay tuned.
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What lab will reject an instrument "due to it being fixed"?! Most contemporary instruments are calibrated without opening the covers, you could literally replace everything inside and just make it emulate the original instrument and no one would be any wiser.
Re:dumpster diving (Score:5, Insightful)
What lab will reject an instrument "due to it being fixed"?!
You used a 10% resistor that seems "close enough" the original was 1%. The calibration lab is used to making "minor tweaks" but having to twist all those trimmers practically all the way is going to take forever and piss them off. On the other hand, in Moms Basement, watching a Star Trek movie marathon while calibrating a scope is considered fun, not a waste of time.
You used inductive metal film resistor which screws up the high frequency performance instead of the specified non-inductive carbon comp resistor. It'll never work above 90 MHz again. The calibration lab will throw a fit because it won't calibrate at 100 MHz. However in Moms Basement you are thrilled to own a "90 MHz scope" even if the front panel label claims its a 100 MHz scope, especially since the highest clock frequency you'll likely subject the thing to anyway is probably low double digits.
You used the totally wrong temperature comp capacitors, and trimmed the rest of the scope so it'll work fine at 70 F. Unfortunately the industrial specs say it has to be calibrated from 32 F to 125 F so it simply can't pass calibration. The calibration lab will throw a fit, although it works fine in Mom's temperature controlled Basement.
That's before you start trying to mix old Tektronix scope silver bearing solders with traditional Pb/Sn and with modern lead free. I understand old fashioned Pb/Sn solder will corrode the plating off the Tek silver solder ceramic things.
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I completely understand what you're saying, but you list some very specific circumstances. A cal lab nominally is supposed to calibrate, not repair, so they'll simply give up when they use up the adjustment range and they're still out of spec. That's hardly rejecting "due to it being fixed" -- any number of things, including simple passage of time, can make an instrument do this. They won't try to understand why it doesn't work, just that following the cal procedure (usually with lots of in-house clarificat
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Our calibration company seals up all edges of the device that give access to its insides after it has been calibrated. Break those seals, and you're in trouble... they'll refuse to calibrate it in the future because of the risk it's been altered. This is forgiven if you provide paperwork from the OEM that they themselves did the repair on the unit.
I don't know that all calibration houses are this strict, though. You could probably find one that would pass your modified instrument if you really wanted.
modern engineers solve problems. (Score:2, Funny)
Like: How am I going to stop some big mean mother hubbard from tearing me a structurally superfluous new behind?
You, sir, are no engineer.
What do you need it for? Frequency range (Score:4, Funny)
Without know what frequency range, voltage range, connectivity requirements (is computer connection USB or serial port?) I cannot help you in your selection.
OTOH you can give me the $2000 and I can give you my blessing.
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Not just funny, also correct. What is your application?
Digital or analog?
What speed signals?
how many channels?
Do you need any fancy triggering (often needed for digital)?
Are you using to for data acquisition or to debug circuits?
I'm not trying to make this tough, but the more you know about your application the better you can do at buying what you need and not a lot more.
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Forget him!
I will give you my blessing for $1000.
O-scope experiences. (Score:2, Informative)
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I recommend NOT buying a Hantek USB oscilloscope.
I got a DSO-2250 which sounded good for the money. I would have spent more time reading reviews, this review sums it up [iinet.net.au].
The software for windows is buggy and limited. They seem to have largely rewritten the software between version 6 and version 7 but have just replaced old bugs with different bugs.
The most frustrating bug is that it gets stuck and stops triggering until you close and reopen the software. It's really annoying to have your hands full poking th
Tek 1012B (Score:4, Insightful)
I'm rather fond of the low-end Tek scopes. The LCD screen is a little slow, and there's only 2 channels, but these are not huge limitations for most basic work. I use these teaching physics and intro electronics to undergraduates - they're easy to use, lightweight, and can store data through USB or pen drives. 100 MHz for about $1200, which is OK for general use.
Re:Tek 1012B (Score:5, Interesting)
Or you can get a $370 Rigol DS1052E [dealextreme.com], and software-hack it to enable 100MHz mode. Not quite as good as a Tek, but significantly cheaper and well worth the money, especially if you're on a smaller budget. I recently got one (it's about time I bought a scope) and I've been quite happy with it for my purposes.
Info on the hack here [eevblog.com].
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It's also worth pointing out that Rigol apparently makes some of Agilent's low-end scopes [circuitben.net] for them, so the fact that they aren't a household name doesn't mean all that much.
The Rigol scope has a lot of nice features that you wouldn't expect to find on a cheap scope -- it can take screenshots and store them to a USB thumb drive or print them to a USB printer, you can connect it to your computer to control it or acquire data via USB or RS-232, etc. It actually oversamples at 1 Gigasample/second -- there hav
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I can second that. I've got a 1012B and I couldn't be happier. It's got hard buttons and knobs for the important stuff, and the menus are easy to use. Plus it's portable if I need to use it in the field (rare).
See Slashdot circa 2001 (Score:4, Informative)
Building a Cheap Oscilloscope Using Your PC? [slashdot.org]
There are some interesting suggestions there.
I'm thinking that some of the more adventurous open hardware folks might think about working on a completely open hardware scope. I mean, what's better than being able to use open tools to build open projects?
Answering myself... (Score:3, Informative)
Actually, there's at least company with open hardware oscilloscopes:
http://www.bitscope.net/ [bitscope.net].
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Are you suggesting that unlike essentially any other kind of electronics, there has been exactly 0 development with regards to oscilloscopes for the last decade? That things cost exactly the same as then, you get exactly the same features and exactly the same models?
If not - why bother pointing to an article that is close to a decade old?
Ebay (Score:4, Insightful)
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50 MHz RIGOL DS-1052e (Score:2)
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And you can software-hack it [eevblog.com] into a 100MHz DS1102E, the hardware is the same.
Converter kit (Score:2)
Depending on what you are using it for it may vary. But a good answer is to buy one of those probe kits that has an AD converter and then plugs into your computer. The computer becomes the oscilloscope via software. There a lot of ups to that like logging and being able to print the output etc. Much cheaper than buying a full oscilloscope and if you plug it into a laptop it is portable.
Get a Digital Radio (Score:3, Interesting)
Probably the best deal would be to get a digital radio. If you can live with ~150Ms/s (a tad slow, but hey), then a cheap thing to do would be to get a digital radio (SDR) system. Say Mercury SDR. Those things typically have a good, 16 bit 100+Ms/s ADC front end, feeding into an FPGA that can do a lot of processing goodies, with low noise, and you should be able to hook up a Tek 7k plugin as a front-end after a few tweaks (simply to get going). You can get everything for $700. You have open source software, full documentation, and you can put a lot of very interesting signal processing on the FPGA. Keeping sampler's speed limitations in mind, you can otherwise easily match performance of many lower-end spectrum analyzers, and $20k+ scopes.
There are no $2k digital scopes with any decent feature set to speak of, even second-hand ones.
If you're into tweaking analog, then a Tektronix 7k mainframe with proper plugins gives you everything you may need. Heck, you can even get a simple logic analyzer for those. With *analog* zoom, no less.
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To get the basics going, you need a working SDR receiver -- you just buy the thing. My coworker recently got one -- the post-processor card with USB output (Cyclone II based), the sampler card with Cyclone III and 16 bit 160 MSPS LTC ADC, and a backplane and power supply. The first two were assembled.
This is quite a decent *receiver*, it has a dynamic range that's pretty much unheard of on oscilloscopes. Would make a half-decent spectrum analyzer, too. Once you add a DC-coupled front end, you may as well ha
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Hardly a multi-year R&D project. If you're handy with VHDL, it can be a couple weekends worth of work -- and remember, most of the hardware is already there for you.
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I'd say that a decent scope must have at least the following:
- zero hold-off time (cheap CCD-based scopes like TDS1k series take maybe a hundred sweeps a second, any scope that can do faster than 100k sweeps/s is either in $10k+ range or is analog)
- very good input overload recovery times (100ns) -- there are no production scopes AFAIK that can offer that, you need a used sampling scope/plugin for that, or you need to look at some LTC appnotes ;)
- proper antialiasing
Once you "splurge" on those, you may as w
Scopemeter 199C (Score:3, Insightful)
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I would second Fluke as a general brand, last I looked they had some sweet portable scopes. All I have is a fluke 87, old meter, but works nicely. My first scope was a heathkit someone else built. second one was a tube type (hey, it was cheap, dual, and HF) tek. I now have a somewhat newer dual trace tek. have had to fix it twice tho. dual trace has unexpected advantages... makes it easy to compare and find the problem when one side goes down ;)
Don't settle for USB scopes (Score:3, Informative)
The USB scopes are maddeningly horrible at triggering, at sample rates, and at aliasing. You're much, MUCH better off going with a stand-alone scope (LeCroy, Tektronix, Agilent) than any of the ones run by PC. LeCroy doesn't seem to provide much in the way of repair schematics, but Tektronix and Agilent are pretty good in that respect. I'd spring for one of the nicer Agilent/HP or Tektronix scopes, frankly, or even a LeCroy, but never something which is limited to being run by PC solely.
What are you looking for? (Score:3, Informative)
This is a bit light on the requirements, but there wasn't exactly a defined need.
So generally speaking you should form some criteria.
Number of inputs, frequency spectrum, what comparative features do you need.
Next, if you are willing to purchase something used and have it tuned/repaired there can be considerable savings. Up one level from this is a direct refurbishing company that guarantees a functional and re-tuned unit.
Now, we all enjoy new and shiny toys, but the trick is being honest with yourself.If it's going to be used for hobby grade activities then don't fall into the trap of wanting the same things you might use at the office. While I would like some of the severs I actually have at work I would not spend the several thousand it would take to actually purchase one of them.
That said I would generally avoid ebay because most refurb shops will sale you the same thing on their site without the wait.
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Indeed, "I need a scope" is very much like asking "I need a computer".
Can you tell us anything more about what sort of projects you want to work on? The problem is that a lot of modern technology now involves signal frequencies that are high enough that the test equipment needed to deal with it is both obscenely expensive and very special purpose.
Some years ago Agilent made a very sexy combination logic analyzer and scope for around $5K (IIRC) which I was lusting after for quite a while. These days their st
USBee (Score:3, Informative)
USBee [usbee.com] has usb-based, software-driven oscilloscopes and logic analyzers to plug up with your computer. Not exactly the old, free-standing devices, but it might work for you. The price looks about right, too.
My take (Score:5, Insightful)
Don't skimp. Get a good one, name brand (Tek, Agilent, LeCroy, etc.) at least 100 MHz bandwidth (the higher the better), 4 channels if you can afford it, some way to get data off the scope and onto a USB drive/network. Everything else is fluff and you can pay for it if you want, but I'd say the above are non-negotiable.
Don't even think about a PC-based scope. A scope is a standalone instrument, always has been, always will be.
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I disagree about "Don't skimp". I've got a 100MHz 2-channel scope from Owon in China, and it is great. Only set me back $300. I could buy ten of them for the price of a single Tek. I also have an old analog Tek but it never gets used.
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Re:My take (Score:4, Informative)
I agree with Andrew. I like having a stand alone instrument that data can be sent to the PC. It really depends on what you're going to be doing as to what you should buy... For $2k you can get a great deal on a used one (like from ebay) but you'll need to do some research first.
Dave does some good reviews here:
http://www.eevblog.com/episodes/ [eevblog.com]
Re:My take (Score:4, Interesting)
Yeah, but the 'scope is a dedicated application with dedicated front panel controls. Windows is merely a widget provider. I've used them, and they're very nice as they support modern hardware and printouts/screenshots are a breeze. But you have to buy the ones with the full front panels - the ones that are just PCs are just... useless and you spend way too much time mousing around clicking virtual knobs. Painful.
$2k can get you a nice basic scope. That's all you need. For the rare times you need something fancy, there are many places that'll rent you the high end scopes for days or weeks. Sure you're paying a good chunk of money for someone else's loan, but unless you can ante up the $10-100K+ for those things, it's far more economical. Get what you can (surely you should be able to find a nice 500MHz scope used?) with what you have to do most of the debugging. When it comes time to debug that obscure thing, rent it.
This way you'll get a good scope for normal use, rent a oh-so-beautiful GHz level scope when you need it or even the fancy-smancy "analog digital" combined scope plus logic analyzer. Those let you analyze bus signals in standard 0's and 1's, while seeing actual signals at the same time. Plus, they can capture the analog signals with the digital, so you can trigger on some oddball logic condition on the bus and see any odd analog waveforms at the same time. But those are expensive - your best bet is renting until you can afford to buy one 10+ years from now.
And if your scope only collects dust instead of signal, you've avoided wasting a pile of money.
Handheld (Score:5, Informative)
I used to be a certified electronics calibration technician, and I've never noticed a difference between the analog and the digital.
If $2k is your budget, and not having any idea what you're going to be using it for, I highly recommend a handheld Fluke. They were just as reliable as the old analog ones, but with more features.
This is the model I'm referring to:
Fluke 125 [aikencolon.com]
Official Fluke 125 page [fluke.com]
aero2600
Got One! The Memory is the Key (Score:2, Informative)
NI Data Acquisition (Score:2)
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Many DAQ cards are notorious for their aliasing problems. You'll be lucky if you find a 2nd order lowpass before the ADC. I've seen cards with 250kHz sampling rate (at 16 bits) that are significantly sensitive (think 30dB down) to stuff at 10MHz. Those are very good -- that is if you want to find cables that have good (low) common mode to differential mode conversion ratios.
It depends on what you're designing. (Score:5, Informative)
I'm an EE who does electronics design for a living, and I've done audio, SMPS, digital, FPGA, you name it. And in each case, the "best scope to use" was different:
- For analog work, or for simple microcontroller debugging, something like a USBee will work great.
- If you're doing higher speed analog, lower-frequency RF or switching power supply design, I'm a huge fan of the Tektronix DPO series. I use a TDS3032.
- For digital work (debugging serial/parallel interfaces and whatnot) I use an old 100MHz "Mega Zoom" HP logic analyzer.
- If I'm doing a design with a big FPGA, bringing lots of extra signals to the FPGA during layout time and using something like Chipscope Pro (on Xilinx FPGAs) to watch what's going on has been extremely handy. No test equipment required!
Re:It depends on what you're designing. (Score:4, Insightful)
- If you're doing higher speed analog, lower-frequency RF or switching power supply design, I'm a huge fan of the Tektronix DPO series. I use a TDS3032.
If you're doing RF you're going to want a spectrum analyzer sooner rather than later.
If you're doing low freq / high power discrete analog (aka SMPS) you're going to want a curve tracer sooner or later, to fool around with if nothing else.
The original article poster has it all wrong, in that a lab that has nothing but an empty desk and a $2K scope simply can't handle the jobs that are easy in a lab with a $500 spectrum analyzer, $250 scope, $750 worth of Hakko (de-)soldering gear, a universal eprom/uC programmer, a logic analyzer, maybe a low end HP protocol analyzer... etc. Don't forget the "obvious" material handling equipment like $500 worth of lights on arms, magnifying glass on arm, low power binoc microscope, ESD protection gear, etc.
Get a used Analog Scope (Score:2, Interesting)
I picked up a used Tektronix 7904 for under $100. Of course, the four probes that I needed cost rather more than the scope, but that's life. The 7904 (with the modules that I have) is a 350MHz unit -- which is great for doing radio work. This setup could easily have cost $10k new.
Buy one of these online and the shipping will kill you. You need to find someone local who wants to get rid of one.
Has anyone tested these? (Score:2)
Digital Oscilloscope DIY Kit [sparkfun.com]
DSO Nano - Pocket-Sized Digital Oscilloscope [sparkfun.com]
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I've built and used the DIY kit. It's a fun, functional project to build but falls short for anything but the most basic o-scope work. It's better than nothing, but its single channel, no trigger input, tiny screen and limited processing power will leave you wanting more.
After almost forty years in the business (Score:4, Insightful)
An employer. Seriously. Every piece of test equipment I've ever owned (some costing upwards of $5000 1978 dollars) was a lousy investment.
Especially when you consider that I have a lab at $WORK with scores of tools costing more than I make in a year, it's stupid to spend my own money on them.
Writing the fine print (Score:2)
Unless you have a personally-negotiated employment agreement, they do anyway. It's not the equipment, it's your time -- which they're paying you for.
$200-300, not $2000... used Tek scope on ebay (Score:3)
You should be able to buy a decent used Tektronix scope on ebay for $200-300, not $2000. Something in the 2200 series, or 400 series. Digital storage scope with 2 channels, A delay B horizontal, 100Mhz bandwidth.
Mod parent up (Score:2)
Unless you're experimenting with some really, really interesting stuff at home, I'd strongly recommend looking through eBay for some slightly used Tektronix gear. I have a TDS420A that I picked up for just over $400, and it does everything I really need. (I do wish it had a USB port for saving screenshots - I hate keeping floppies around just for the scope.) Seriously, it's a great little scope. Save some cash and put it towards other gear, like a used programmable power supply, or a function generator,
For what it's worth! (Score:3, Informative)
Another +1 for Tektronix (Score:2)
I got a DPO4034 and its great. 350MHz, 4 channels, can do I2C/CAN/SPI bus decoding and Wave Inspector rules.
Solved (Courtesy of Peter Hiscocks at TLUG) (Score:5, Informative)
... at http://gtalug.org/wiki/Meetings:2005-12 [gtalug.org], Peter demonstrated the virtual oscilloscope and virtual function generator applications, which are available as open source.
The hardware unit (approx 3 x 6 x 1" thick) is available at http://www.syscompdesign.com/CGR101.html [syscompdesign.com]
--dave
Spoiled engineers! (Score:2)
If you can find one get a digital O-scope.
I did a physics lab for E&M at UCSD and the physics department works with analogue O-scopes... they were the source of all my hate that quarter, all of it.
I then heard from an engineering buddy that over in their dept. they had digital O-scopes that didn't need to be calibrated or adjusted! and they had units on the lines! The time I could have saved working with LCR's with a digital... I can only imagine!
Re: (Score:2)
I grew up with analogs and have no problem using them now. In my experience, the best part of having a digital 'scope is that it's small and light. :)
Triggering is the gold standard (Score:5, Informative)
The difference between a 'scope that is a joy to use and one that is useless and frustrating is triggering. Good triggering is what gives you ease-of-use. You can't see it if the 'scope can't trigger on it. This is especially true when you are trying to catch a glitch.
In my experience, Tektronix 'scopes have always been easier to use because they triggered better than the competition. We got a bunch of money once and decided to buy new oscilloscopes. Since we worked for the government, we had to write up a tender so there could be a fair competition. It drove us nuts. The specifications for the other brands were as good as those of the Tek 'scopes. We had used the competing 'scopes and hated them. We had to bend like pretzels to get a specification that would ensure that we got the 'scopes we wanted. The specifications just don't do a good job of describing how usable an oscilloscope is. (ditto for spectrum analyzers)
The Tek 'scopes were bullet proof. I could throw my 'scope in the back of a station wagon, drive to the airport, hop on a rented plane, fly five hundred miles, hike up a mountain and the Tek 'scope would ALWAYS work when I got to the job site.
These days, with digital 'scopes, a good test is to throw a nasty waveform at the 'scope and press the autoset button. If you're looking at something useful, the 'scope is good. If you're looking at garbage, the 'scope is garbage.
These days, I have an ancient Tek (circa 1970) 'scope on my bench at home. It works great for most of my home projects. At work, I have access to 'scopes that will do 1 GHz. My buds at the NRC have a 'scope that does 6 GHz. Somehow all the 'scopes are Tektronix.
Since I started in the industry in 1974, Tektronix has made the best oscilloscopes. Some of their other stuff is crap IMHO but nobody else can touch their 'scopes. I'm teaching college now and we prefer to buy as cheap as possible. Whenever we've tried something other than Tek, we've regretted it. The Tek 'scopes have the advantage of being student proof!
For other test equipment, I would choose other manufacturers. HP/Agilent would be my choice for almost everything else that isn't an oscilloscope.
Complete setup for under $1200 (Score:3, Informative)
Scope? (Score:2)
Without stereotyping any more than necessary, and lacking any detail about the projects you have in mind, I'm going to guess that with your background (CE+CS) you're probably working more toward the digital side of things - that is, you're more likely to need the scope for debugging why your I2C transactions are failing than checking if your homebrew PLL is working. In this case, rather than a fancy scope you might be best off with an 8- or 16-channel logic analyzer that happens to include basic scope funct
Define what you need, go to ebay (Score:5, Informative)
One reason I mention these is because newer scopes, particularly the Tek 3000-series, while incredibly useful because of their size, weight, and connectivity (they have a linux-based OS that includes a webserver so you can plug one in with a cat5 and control it from your desk remotely: pure awesome!) are just about impossible to repair. Everything, *everything* is in custom silicon. On a LeCroy you can swap out the input amps if you burn one, swap out the timebase card or the A/D cards for each channel. It's like working with an old PC, as opposed to an ipod.
Also, budget for probes. Get probes rated for at least 1.5 times the scope's bandwidth: usually people ship probes that have the same bandwidth as the scope's max, but the spec on them actually means they're at something like -3dB and pretty fuzzy at that bandwidth. I got 500's for my 350mhz scope and they're beautiful. A lot of people sell broken probes and I've found, in the three I've purchased, that in every case it was a broken solderjoint where the probe cable met the board that attaches to the scope BNC. I reflowed it (no added solder for fear it'd mess with the tuning) and got three new probes for cheap.
There are people selling vintage scopes on ebay that have NIST certification, if that's important to you, but you can also get it independently certified if you need it. Newark.com has cal services, to my surprise. (They're who we use at work.)
I personally dislike Yokogawa scopes because their interface doesn't make sense to me. I can sit down at an Agilent or Tek or LeCroy and get it to do what I want pretty quickly (digital LeCroys are weird about horizontal offset) but Yokogawas I spend a lot of time reading the manual. But they're nicely engineered.
The USB scopes I've used were disappointments to me: the $ per mhz isn't competitive with a used scope, and they're typically pretty tied to the company software, which might not do what you want.
go for 4 channels (Score:5, Informative)
If you're a C.S. person, it's likely that you are a digital person, and you will most frequently use the oscilloscope to troubleshoot digital busses. Don't skimp on the channel count, go for 4! For things like serial busses (RS-232, SPI, I2C, etc.) you will want to watch clock, tx, and rx simultaneously. For a parallel bus, you can get your clock, chip select, and a couple addy or data lines. For most problems on your board, you can get by with the scope instead of an expensive logic analyzer if the scope has enough channels. The scope is better than the logic analyzer in many ways as you can watch for issues with noise, bus contention, etc.
Every engineer has their bias, I say go for Tek! LabVIEW and DAQ are cool for repetetive measurements under automation, but there's just no substitute for a physical front panel interface with knobs and buttons when you just want to spend a couple minutes looking at a few levels.
Try to find something with Ethernet or USB. Many of the used scopes on ebay have the old 3.5" floppy, and that becomes annoying when noone in the office remembers floppy disks and you need to get a plot off the scope to send to an FAE! :)
How much bandwidth do you need? (Score:2)
The basic question with an oscilloscope is how much bandwidth you need. Price goes up with bandwidth. 100 MHz is around $200. 80 GHz is around $24,000.
If you want to see what a PC motherboard or a cell phone radio is really doing, it's very expensive. If you want to see what an Arduno is doing, it's not so bad.
Do not invest so much (Score:2)
Scope is a thing of the past (Score:3, Interesting)
I hate to say this as a former Tektronix engineer, but you seldom need a scope, and if you do it is typically application targeted and expensive. So the general purpose scope that all self respecting EE's used to have on the lab desk is a thing of the past.
All digital work either has debuggers or with FPGAs, Chipscope Pro or other. No scope needed. And if you really need to see how the eye diagram looks with your 10GB Ethernet, the best scope may be your receiver chip. Hard to find a 40GHz scope anyway.
I actually had a Tek 2440 300MHz Digital Storage for at least a decade, but used it less and less. Became more a educational thing to show kids how AC looked. All serial interfaces are running at muli GHz speed, and RF development is more in the 5.7GHz range and higher (802.11n) Not many scope sampling at 4x or more at those frequencies.
Re: (Score:3)
I disagree. My basic Rigol DS1052E has solved many weird problems with microcontroller projects over the past months.
Without the scope I would never have figured out that my I2C master and I2C slaves for a project were playing "Bus Fighter I2C: Noncompliant Master". (I thought the firmware on the master was using hardware I2C mode, but it was actually using a bad software I2C implementation that actively drove the clock and data lines high. Bad Things happened if a slave tried to do clock holdoff.) I mi
Textronix Type 547 -- aka "the chick magnet" (Score:3, Funny)
The 547 is the Barry White of bench top instruments. Its muscular aluminum frame is massive, yet understated. Dual independent time bases tells the ladies you've got a light but agile touch on the trigger circuits.
Truly, this is a scope for a discerning bachelor geek. When you meet an interesting woman, casually mention you've got a type 547 back in your apartment and she's bound to fish for an invitation. Then if later she cannot, in an intimate moment, resist playing with the plug-in unit, propose marriage on the spot.
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Personally I find traditional non-storage analog scopes pretty much useless for digital stuff. Really you can only use them if you can arrange for the signal in question to output a simple pattern that repeats infinitely.
Never used an analog storage scope but from what I hear they aren't exactly great for high speed stuff either.
One exception: if you can stretch your budget to get a used TDS3000 or TDS3000B series scope, that would be a good way to go.
There is one listed on ebay buy it now right now for the
Re:Buy a cheap digital scope and a good analog sco (Score:4, Insightful)
Before plunking down good $$, I'd wait and see what sort of equipment is *really* needed. Scopes are a nice tool, but there are other tools like good spectrum analyzers (with waveform analysers) and other gear that can add up quickly. I'd say, let the need present itself, then invest to the need.
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Afaict Lecroy are generally regarded as the top brand in scopes but with a price tag to match with agilent (former HP) and tek taking up the middle of the range and the far eastern vendors covering the crappy end of the market.
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For audio stuff non-storage scopes are fine. Because when troubleshooting audio you would typically put a repetitive test signal in (or if you are building a synthisyser make it generate one).
For microcontroller work however you really want to be able to look at a fairly complex waveform. If you try this with a traditional scope even if you can arrange for it to be repetitive (which is sometimes quite difficult) the scope is likely to keep triggering at different poitns in the waveform. So you really want a
Because Women are tools you build in your garage? (Score:2)
nt.
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