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Education Hardware Technology

Cheap PC Oscilloscopes - Any Recommendations? 321

Missionary Man asks: "I'm an electronics teacher looking for a good (but reasonably cheap) PC based oscilloscope for classroom demonstration purposes. I've done a reasonable amount of research and come up with a few contenders. Ideally I'd like something with a bandwidth of up to 40MHz and 2 channels. Does anyone have any tales to tell regarding the use of any of these scopes (or any others I haven't found or mentioned) and can recommend a suitable device?"

"Here's the list of my findings so far:

  • The DS2200C from USB Instruments will do 2 channels at 12 bit resolution, but only to 200KHz.
  • The PCS100 from Velleman at QKits runs to 12MHz, but only 1 channel. It has a bigger brother, the PCS500, that has 2 channels and 50MHz bandwidth, but is a lot more expensive.
  • Picotech do cheaper ones, like the ADC-40/42, but these only operate in the KHz ranges.
  • Link Instruments sell the DSO-2102S that runs to 60MHz with 2 channels, but it's a bit out of my price range.
  • Finally, I found the bitscope which seems to be just what I'm looking for, combining a 2 channel scope and an 8 channel logic analyzer for a reasonable price.
I'm hoping to spend US$300-$400. I recognize the software is a fundamental part of the successful operation of these units and any comments regarding the bundled programs would be most helpful too!"
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Cheap PC Oscilloscopes - Any Recommendations?

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  • by lukewarmfusion ( 726141 ) on Friday February 27, 2004 @08:58PM (#8413502) Homepage Journal
    I see them on case modding sites occasionally. As far as your use, I'm not sure how they would measure up. Knowing the thriftiness of many modders, you may be able to find a decent recommendation there.
  • by MikeDawg ( 721537 ) on Friday February 27, 2004 @08:58PM (#8413505) Homepage Journal
    Check this one [softdsp.com] out. . . I don't know the price because their price page is broken. . . It looks like everything you need in a PC Oscillioscope.
  • winamp? (Score:5, Funny)

    by VegetariMan ( 162508 ) on Friday February 27, 2004 @08:58PM (#8413507) Homepage
    I think my media player has an oscilloscope...
    • Re:winamp? (Score:2, Interesting)

      by Anonymous Coward
      That brings up an interesting question. Could a circuit be devised that would take an external frequency outside of hearing range, and enable it to be fed into the audio input of a soundcard, so a media player's oscilloscope would work?
      • Re:winamp? (Score:3, Informative)

        by unitron ( 5733 )
        Beat it against a local oscillator set to a frequency such that the difference of the two lands between zero and 20 thousand cycles per second (Hz). It's called heterodyning and has been used to shift frequencies since the early days of radio if not before.
    • Re:winamp? (Score:5, Interesting)

      by seanadams.com ( 463190 ) * on Friday February 27, 2004 @09:08PM (#8413578) Homepage
      You know, for classroom demonstrations a sound card should be perfectly acceptable for all kinds of things... especially considering that there is also very nice free spectrum analyzer software available. On top of that, students can easily repeat experiments on their systems at home. Of course with a max sampling rate of 48KHz there's only so much you can do, but low speed osciallators, R/C circuits, switching power supplies and all sorts of things can still be seen to a useful extent.
      • Re:winamp? (Score:5, Informative)

        by FredGray ( 305594 ) on Friday February 27, 2004 @09:21PM (#8413666) Homepage
        You know, for classroom demonstrations a sound card should be perfectly acceptable for all kinds of things...

        My understanding is that sound card inputs are AC coupled, so you won't be able to see anything much slower than about 20 Hz. That might be OK, but it's not quite an oscilloscope.

        • Re:winamp? (Score:5, Interesting)

          by seanadams.com ( 463190 ) * on Friday February 27, 2004 @09:26PM (#8413693) Homepage
          Good point... I think you could probably address that by bypassing the cap on the input, but then your "zero" level would probably be 1.15V.
          • Re:winamp? (Score:3, Interesting)

            by Anonymous Coward
            what you can do is make an 'audio chopper'(easy to make.. see google). get the DC from your electronics and reverse polarity every 1KHz from the DC to make it AC. software can then reconstruct the original DC signal. Works ok (minus some chirps every 1KHz)...
        • Re:winamp? (Score:3, Interesting)

          by keeboo ( 724305 )
          plus i don't know any "winamp-like osciloscope" that stabilizes the waveform.. so what you see is not a pretty standing waveform but something chaotic and not really useful.

          not mentioning that you don't have the V measurement (ok.. i guess you can write in the monitor using a soft pen ;)

          since the guy is mentioning software i assume he doesn't feel (or is not able to) write one himself, so the soundcard option is not a good option for him.
        • Re:winamp? (Score:5, Interesting)

          by Rebar ( 110559 ) on Friday February 27, 2004 @11:18PM (#8414188)
          Depends on the size of the capacitors on the input side of the sound card - the larger the RC time constant, the lower the frequency signal that can be observed. My old SB compatible card could pick up as low as 3hz signals really easily - I had an animometer hooked directly to it and counted zero-crossings to determine the wind speed. The signal may not be that linear under 20hz, but it's still really easy to see.


          I agree with the parent post about a sound card being a nice classroom demonstration scope. For higher mhz, you can pick up a real scope from Ebay for much cheaper than a PC card solution.

        • by rsw ( 70577 ) on Saturday February 28, 2004 @12:57AM (#8414572) Homepage
          So modulate in hardware and demod to baseband in software.

          With a simple analog multipler (for example, the Analog Devices AD834 [analog.com]) and e.g. a 5 KHz oscillator, you can AM a band-limited (say, DC-500 Hz) signal, put it in your sound card, then do the demod in software (another multiplication will work).

          This will cost you, in total, about $5 (you can get free samples of the AD834 and you'll need some resistors, some caps, a couple op-amps, and some wire) and will give you DC-500Hz through your modulator or 20Hz-24KHz without it. Not too shabby, especially compared with $500.

          By the way, if you're going to spend $500ish anyway, why not pick up a Tektronix 2445 or 2465 on EBay? The 2465 has 350MHz bandwidth and is, IMHO, one of the nicest all-around scopes out there.
  • Bankruptcy Auctions! (Score:5, Interesting)

    by Supp0rtLinux ( 594509 ) <Supp0rtLinux@yahoo.com> on Friday February 27, 2004 @08:59PM (#8413512)
    Search google for bankruptcy auctions. I'm sure you can find what you're looking for. I work for a biotech that saved 75% of our initial budget by acquiring medical laboratory supplies from six other biotechs that went bankrupt in recent months. We did such a good job, our VC company gave us more than we asked for to buy the rest of what we needed.

    The only thing necessary for Micro$oft to triumph is for a few good programmers to do nothing". North County Computers [nccomp.com]
  • Tax purposes... (Score:2, Informative)

    by teledyne ( 325332 )
    This is a little bit OT, but you can write off any purchases required for work, this includes education. Perhaps writing off that expensive oscilloscope would be equivalent to not writing off a less featured model.
  • by Anonymous Coward
    For cheap demo purposes, consider using the analog sound ports (line-in). I have had good success doing that for lower speed (44.1K).

    I was looking for a PC based scope but couldn't find quite what I wanted.. I recently bought a used Tektronix 2215 for $50.

  • by ObviousGuy ( 578567 ) <ObviousGuy@hotmail.com> on Friday February 27, 2004 @09:04PM (#8413558) Homepage Journal
    I sometimes think back to my college days and really regret that I didn't focus more on the hardware side of computer engineering, primarily delving into the Computer Science land of algorithms and language design. In the last several years of my employment in the embedded space, I have come into contact with more hardware than you could shake a stick at, and without that grounding in hardware that I should have gotten in school I feel a little overwhelmed when faced with anything deeper than a block diagram.

    I also wish that teachers like yourself didn't have to worry about providing materials like this within such a tight budget. It doesn't sound like this is just for this year's class, but something that can be used year after year. $300 for a material that can be used multiple times seems very cheap, especially considering the intrinsic value of the tool. Schools should be at liberty to spend what is necessary to bring the classes up to exceptional levels. Considering how the U.S. lags behind most other modern Western nations in Math and Science, such tight-fisting seems to be one significant factor in this drop off.

    Good luck in finding the right tool.
    • Schools should be at liberty to spend what is necessary to bring the classes up to exceptional levels.

      I have two words for you: lowest bidder.
    • by aastanna ( 689180 ) on Saturday February 28, 2004 @02:42AM (#8415054)
      Sounds to me like the question is from a high school teacher. I seriously doubt spending any more on a scope would be worthwhile, since I'd bet it's primarily going to be used to show students wavy lines, or maybe as a glorified multimeter (he's only buying one, so it's not like the students will be using it regularly). I wish the poster gave a few examples of the types of projects his class works on.

      That said, I wish schools would stop blowing their entire budgets on computer labs. I hate to see a school paying for a computer that isn't at least two years old when the money could be going to text books that aren't twenty years old and falling apart.

      It would be really nice to see high school electronics courses teaching students how to properly work a scope, but you'd need enough for an entire class. It's amazing how many engineering students get 2 years into a computer/electrical engineering program and don't know how to use a scope to read important parameters from a circuit.
  • Educational device (Score:5, Insightful)

    by Rosco P. Coltrane ( 209368 ) on Friday February 27, 2004 @09:04PM (#8413559)
    Two thoughts about your question:

    - Do you really need 40MHz for educational purposes? Unless this is a device to be used in a college or higher education class , you can display sub-10KHz signals to teach a class how to use a scope.

    - When I was at school, I learned how to use a real scope, with knobs and buttons and a not-so-perfect green screen, and I reckon it was way better to touch these dials and controls and have a direct feel for what they did on the screen than set some virtual thing and grab perfect-looking samples, to understand how things actually worked.

    In short, any old regular scope that's well explained by the teacher is probably better than any interface+software setup that "isolate" the student from whatever electrical phenomenon he's trying to expose.
    • by Enuteez ( 728192 )
      Do you really need 40MHz for educational purposes? Unless this is a device to be used in a college or higher education class , you can display sub-10KHz signals to teach a class how to use a scope.

      They might need the higher bandwidth - seeing what the kids these days are doing in every aspect of technology, blows away anything I ever came close to. A good tech teacher won't stick to old curriculum, but try to expand the class as close to the leading edge as they can.

      As far as getting a scope, I too
    • by Rolo Tomasi ( 538414 ) on Friday February 27, 2004 @10:08PM (#8413908) Homepage Journal
      Scope bandwidth - you can never have enough. If your budget is limited, you're better off with a good old analog scope. Digital bandwidth is too expensive. Calculate 10 samples per Hz of the signal that you're sampling. So, if you're looking at a 40 MHz sinewave, you need 400 MSPS. And that's just to roughly make out the shape of the waveform, 800 MSPS would be better. Just imagine what a single period of a sinewave looks like when it's divided into only 10 discrete levels. Looks like a staircase.

      The other thing to consider is the input amplifier bandwidth (this applies both to analog and digital scopes). This is also known as slew rate. It describes how fast the input amp can follow a signal change. Imagine an ideal square wave with zero rise time. It has infinite bandwidth. What does this mean? If the signal has a faster riset time than your input amp, your edges will be smoothed out. If I look at the output of a 40 MHz TTL oscillator (which outputs a squarewave) with my 60 MHz scope, I see what is almost a sinewave. "60 MHz scope" means the scope can display a 60 MHz sinewave. The sinewave is the waveform with the slowest slew rate. All other 60 MHz waveforms will also look like a sinewave on this scope. If you want to analyze square waves, your scope will only show a halfway accurate depiction of the signal if it has upwards of ten times the bandwidth of the signal.

      There are also problems when measuring high bandwidth signals. Above about 80 MHz, you need to use BNC jacks on both sides, properly terminated with 50 Ohms, or the stuff you see on your scope screen will have very little to do with the actual signal. Not many outputs can drive 50 Ohms. You need to build special prototypes of your stuff that are intended for scope measurements. You can't just take a scope to your CPU or stuff like that.

      If I had to make a recommendation, get a 60-100 MHz analog scope in good condition. Tek 465 is a good model.

      If you want to look at digital stuff, get a logic analyzer. There are some interesting DIY projects on the web.

      For higher frequency or RF stuff, a spectrum analyser can't be beat. But good ones cost more than a luxury car. If you're really serious, there are DIY projects on the net for that, too.

      • by R2.0 ( 532027 )
        For used scopes:http://sphere.bc.ca/test/

        While you are at it, grab some slide rules and Nixie tubes.

      • by cybermace5 ( 446439 ) <g.ryan@macetech.com> on Saturday February 28, 2004 @01:04AM (#8414600) Homepage Journal
        A 465 is good, but a 465B is better. The Tek 465 is about 30 years old now, and the 465B is only 20 years old. I was able to pick up a nice 465B with all manuals and accessories on eBay for $100 recently.

        If the poster really wants a digital oscilloscope, head on over to fpga4fun.com [fpga4fun.com]. There's some neat little FPGA projects, based on a little FPGA board the guy designed and is now selling for $50. One of the applications is a digital sampling oscilloscope; it actually looks pretty neat. With the FPGA board and ADC board, it's pretty cheap too.
    • by I don't want to spen ( 638810 ) on Friday February 27, 2004 @10:36PM (#8414027) Journal
      Very off-topic, but I remember seeing a demonstration 10-15 years ago of the latest Spectrum Analyser, where the salesman made a big deal of the battery backed RAM saving the settings when the device was switched off. One of the older engineers said "we've got that on the analogue spec analysers, we call it a knob."

  • Remember that the oscilloscope bandwidth close to the frequency of the waveform being measured distorts that waveform. (In phase if the frequency being measured is a sine wave.) You need an oscilloscope bandwidth maybe 3 times the highest frequency being measured.

    ICs often have very high potential bandwidths, and, when something goes wrong, even an audio IC can have sometimes have parasitic oscillations at extremely high frequencies. If you are working on a circuit, you need to be able to see those parasitic signals.

    I don't like this fact, because it is expensive, but 100 MHz seems to be a good oscilloscope bandwidth. I bought a very old Tektronix scope to get the needed bandwidth at a reasonable price.
    • by Anonymous Coward on Friday February 27, 2004 @09:10PM (#8413598)
      it's *5* times the signal.

      see the tektronix documentation, for ex. 2x is the standard shannon-nyquist theory, but to get proper results, go 5x. tek has a huge document on it, quite informative.
  • Educator? (Score:5, Informative)

    by StupaflyD ( 729788 ) on Friday February 27, 2004 @09:08PM (#8413585) Journal
    If you're truly an educator:
    *Here is a link to Agilent's educator page complete with educational discounts etc.
    http://www.educatorscorner.com/index.cgi?CONTENT_I D=66
    *Write to sales reps at different companies, Tektronix, Agilent, etc... and plead for donations.
    *Write/apply for a grant for add'l $$ (after all, you get what you pay for in regards to scopes)
    *If all else fails, peruse *cough* ebay, or *cough* broken windows at ___ Electonics Supply... [grin]
    • Re:Educator? (Score:5, Interesting)

      by NoseBag ( 243097 ) on Friday February 27, 2004 @09:26PM (#8413695)
      Ya left one out. Write/go to any local company doing e-tech type manufacturing or engineering. Ask if they'll donate their old obsolete eqpt that they've already written off. I've never been in an engineering lab yet that didn't have at least one dinosaur in it.
      • Re:Educator? (Score:3, Informative)

        by afidel ( 530433 )
        Good point. I know my last client was a wireless equipment manufacturer and when they went from 900MHz for 802.11 to 2.4 Ghz for 802.11b their old equipment was worthless because it mostly topped out at 1GHz. The old equipment was sold off to employees but they probably would have been just as happy to give it to an educational institution if they had been asked.
  • Not PC (Score:5, Informative)

    by linuxwrangler ( 582055 ) on Friday February 27, 2004 @09:08PM (#8413587)
    OK, I know you asked about PC based scopes but if a plain old scope will do the job consider used.

    A friend of mine bought a couple at a ham radio swap meet from a guy who buys surplus lots. IIRC they were dual-trace and something like 20MHz (he ended up getting one for me and for several other interested friends).

    They were selling for ~$20 which means you could have a scope for every student in a class of 20 and still stay in your budget.
    • Re:Not PC (Score:3, Insightful)

      by drinkypoo ( 153816 )
      I was thinking that one advantage of a PC scope is that you could project it. It would be neat to project that, and then next to it project an enlarged view of what you're doing, say probing a PC board. I don't know if this person is doing this or not but it's certainly one option to consider. Projectors are getting cheaper all the time, they're pretty readily available now.
  • Must it be PC-based? (Score:5, Informative)

    by Hayzeus ( 596826 ) on Friday February 27, 2004 @09:09PM (#8413588) Homepage
    You can generally get excellent deals on analog, non-pc based scopes on eBay. I use a Tektronix 2235 100mz dual trace unit that only ran me around USD $200 -- and this was a few years ago.

    I also have an Ozi-Fox handheld that has a PC and/or palm-based interface. It only does 20mhz and is single trace, but they are fairly inexpensive (< $90.00 USD) -- you could buy multiple units for classroom use. The display on the unit itself is not great, but works well for quick-and-dirty work.

    Good luck -- m

  • by NotQuiteReal ( 608241 ) on Friday February 27, 2004 @09:09PM (#8413590) Journal
    I haven't messed with it in a while, so I don't even know if there is software out there for modern OS's. But back in the day, if you are willing to use a real pc as your input device, and get a "good" sound card; with a high SN ratio and some software to be a "cheap scope".

    After all, a DSO is "just" a D/A, and the input of sound cards is the same.

    Maybe the sample rate on sound cards is not high enough, but the specs on some of the latest SoundBlaster (creative labs) cards are impressive (106dB...).

    If you really need a good scope, you'll likely have to spend money. But if you are a hobbiest who just needs to see basic waveforms, maybe there is some good, cheap software out there that takes advantage of commodity soundcard hardware?

    • 106dB isn't a sample rate, that's gain...

      I think the real issue with using a soundcard *is* the sampling frequency (44kHz? 96kHz maybe?) and you'll probably let out the magic smoke if you plug more than a few volts into it so you need some sort of voltage divider there for many signals. Plus I don't know how much filtering is done on the line-in side.

      That said I'd say it may be more cost effective to get some used stuff. I spent about $100 on ebay for an old Tek 465. 100MHz, good condition. And I can
    • One thing that everyone overlooks with a soundcard 'scope'. It's AC coupled only - there is no way to measure DC offsets.
      The other thing that should be mentioned is the fact that the line input doesn't exactly qualify as calibrated. Whilst this doesn't always matter too much, it is still a limitation. You'd need a good known signal level (AC signal, obviously) to provide any form of (non-NIST-traceable) calibration.

      Also, don't forget that the input range is very limited. In order to provide a useful volt

  • Why PC tethered? (Score:5, Informative)

    by Jeff DeMaagd ( 2015 ) on Friday February 27, 2004 @09:11PM (#8413604) Homepage Journal
    It seems people on slashdot are a bit overeager to buy PC based devices that can't be used as a standalone device. So far that I've seen, the benefits are mostly just cost, at the expense of portability, usability and quality.

    I'd just find a real scope on surplus somewhere.

    I just have a 'scope on "loan" from a local EE guy. Just an analog one. Effectively it is mostly a gift, but there are times he wants an analog scope so he wanted the understanding that he can get it back on occasion. For most uses, a digital one does fine.
  • by Jerk City Troll ( 661616 ) on Friday February 27, 2004 @09:11PM (#8413608) Homepage

    It is not difficult to find a veritable mount of cheap oscilloscopes [ebay.com] on eBay. You say you only need it for demonstration purposes, so why do you need something shiny and new? It can even be argued that the older analog oscilloscopes are better than newer digital ones. As always, resort to eBay if you need something not so good, and fairly cheap. Chances are you can find it there.

  • by G4from128k ( 686170 ) on Friday February 27, 2004 @09:14PM (#8413619)
    If a 2 channel audio frequency scope is all you need, then Oscilloscope 2.5 for Windows [phys.msu.su] might do the trick. It uses the inputs on a standard sound card to grab 2 channels at up to 20 kHz. Disclaimer: I've not used it and a bit of Googling may find better alternatives.

    Its slow, but is free (assuming you have the sound card).
    • You've got limited voltages when using a sound card based solution. Free is good, but it's usability is near nil. Not to mention that a sound card's dsp may muddle the input.

      RS232 is 9-11 volt in of itself...

      Also, if they're doing PIC or 8051 work, having at least a MHz or 10MHz scope is handy to follow any of the bus / etc lines.
  • by John Miles ( 108215 ) * on Friday February 27, 2004 @09:16PM (#8413630) Homepage Journal
    ... can download free/open-source plotter emulation software at http://www.qsl.net/ke5fx/misc/7470.zip [qsl.net]. This may be helpful to you if you buy an older scope from eBay. It will let you grab screenshots, overlay them, print them, and save them in several formats including their original HP/GL-2 plotter language. You can see some typical screen captures at http://www.qsl.net/ke5fx/synth.html [qsl.net].

    I use a Tek 2430A on my own bench. These are great scopes -- you can get 150 MHz bandwidth for about $400-$600. A National Instruments GPIB adapter to interface it to the PC will set you back another $100.

    I'm trying to add support for as many instruments as I can to this package. Any interested parties should feel free to email me...
    • 2340A ... (Score:3, Informative)

      by __aadkms7016 ( 29860 )
      Happy memories of my 2340A, but I dunno if I
      would recommend spending cash to buy one on
      the used market ... they ran so hot, and their
      mean-time-to-failure reflected it. We had a few
      dozen under our control (research lab + class lab),
      and there would always be a few with little yellow
      Post-Its on them waiting to be sent out for repair.
  • Try the USRP (Score:5, Informative)

    by gustaffo ( 598224 ) on Friday February 27, 2004 @09:17PM (#8413641)
    If my understand is correct, some of the guys from the GNU Radio Project [gnu.org] have developed a USB based software radio device that works with in linux. It is called the Universal Software Radio Peripheral. [comsec.com] I think the first prototypes have shipped. The cost is pretty close to your price range. You can see it in action running an oscope program here. [comsec.com] And of course it can be extended to do many more exciting things.
  • Bitscope (Score:5, Informative)

    by GigsVT ( 208848 ) on Friday February 27, 2004 @09:19PM (#8413657) Journal
    Since no one who's replied has answered your question, instead choosing to talk about unrelated things, I have to say that I'd go with the Bitscope.

    Visit #electronics (our electronics+open source channel) on irc.freenode.net if you want to discuss.
  • nyquist frequency (Score:5, Informative)

    by jonniesmokes ( 323978 ) on Friday February 27, 2004 @09:23PM (#8413679)

    Missionary Man asks: "I'm an electronics teacher... ...Ideally I'd like something with a bandwidth of up to 40MHz and 2 channels.


    The bitscope only has a 40MS/s data aquisition rate. Assuming that that's for both channels - 20MS/s each, then your left with a nyquist of 10Mhz. And you really need to oversample a waveform a lot more than x2 to see what it looks like. The analog bandwidth of the bitscope is high, but the A/D conversion will result in a lot of aliasing. That said. Its a really impressive unit for $400.00. I didn't think you could find something nearly that fast for under $700. Not exactly what you're looking for.

    The software for a scope is pretty important - but without the raw A/D speed and resolution you won't get very far.

  • by pvera ( 250260 ) <pedro.vera@gmail.com> on Friday February 27, 2004 @09:40PM (#8413753) Homepage Journal
    DRMO = Defense Reutilization Marketing Office

    This is the military agency that sells surplus equipment to the public. They usually have stuff like what you need.

    If you can find something that has a HPIB/GPIB bus connector (IEEE-488) then you can connect it to a PC and use program your own interface (the libraries are very simple and very well documented). We did this both in the Army and also at a commercial satellite communications company (ours was to interface with HP spectrum analyzers thru IEEE-488).
    • ...and the old PCIIa GPIB-interface cards for the PC (they have a 8bit ISA bus!) are supported by linux-gpib since not long ago!

      http://linux-gpib.sourceforge.net/

      They are no longer supported by national instruments since windows 3.11/DOS, so you can get them very cheap (or for free) and they work very well under linux!
  • by francisew ( 611090 ) on Friday February 27, 2004 @09:56PM (#8413843) Homepage
    softdsp.com
    I bought one two years ago (around 800$ canadian)
    it's pretty good, does 200 MHz / (5 GigaSamplesPerSecond equiv., whatever that means), two channel, USB.
    The software isn't great. I don't think there is a linux port... I'm lazy, haven't checked recently.
    The actual device is really sweet. If I haven't blown it up in two years, it is pretty solid! (I'm a chemist, and I do things like attach 400V power supplies to it randomly, I'll feel bad if it dies. Or me.)
    Good luck!
  • Labview (Score:3, Informative)

    by Anonymous Coward on Friday February 27, 2004 @09:56PM (#8413846)
    If you really want to give your students a head start, I'd suggest finding any cheap scope with a GPIB interface and get an educational copy of the LabView software

    http://www.ni.com/academic/edu_dsct.htm

    (you should double check that the educational version actually supports GPIB because I don't recall if it does).

    There's a hell of a lot of corporations out there that use LabView for all their test equipment, so there's a good chance your students will run into it when they get jobs.
  • PCI based oscope (Score:5, Informative)

    by Triode ( 127874 ) on Friday February 27, 2004 @10:01PM (#8413868) Homepage
    Many people make them, and they are real oscopes on
    a PCI card... but the ones I have used were GaGe...

    http://www.gage-applied.com/

    Should not be too pricey, and I think they have
    educational discounts. They are the best option
    I have seen to get a real oscope in a computer, and
    the sampling rate and digitization will beat a sound card hands down.

  • by Ho Kooshy Fly ( 561299 ) on Friday February 27, 2004 @10:07PM (#8413892)
    Personally you have to be careful about many of the "PC" based scopes that are out there. They usually suffer from bad analog bandwidth and short memory depth. Also you have to pay particular attention to many of the voltage/impendance limits of "PC" scopes.

    Personally taking a trip down to your local electronics swap meet is not a bad idea if you have one nearby. Hear in SiValley there are a few around on the weekends where you get some older Tek/HP *cough* Agilent scopes for pennies on the dollar. Sometimes they need some work but most people are honest about it.

    -Ho
  • Why do you need 40 MHz?

    There isn't anything you can do at 40 MHz on an o-scope that you can't do at 2 MHz that won't be sufficient as a demo for the kids.
  • One to Avoid (Score:5, Informative)

    by certsoft ( 442059 ) on Friday February 27, 2004 @10:34PM (#8414014) Homepage
    I bought a PC Multiscope from Jameco and found out that it didn't actually sample both channels simultaneously, making it basically worthless. One of the things you want to be able to do is to look at clock and data lines and measure the timing between them, and for that you need simultaneous sampling. Needless to say, that pile went back to Jameco.

    I bought a DSO-2100 from Link Instruments and have been very pleased with it. Probably one of the best investments I've ever made.

  • Optascope (Score:5, Informative)

    by GarthSweet ( 514087 ) on Friday February 27, 2004 @10:41PM (#8414047)
    I have an Optascope 81M USB scope from
    http://www.optascope.com
    I recommend it highly. Nice software and really works well for me. Also only $189.00!

    Specs are:
    1 Ms/S Maximum Sample Rate (500Ks/s 2 channels)
    200 KHz Bandwidth
    20Vpp Max Input for CH1 & CH2
    8 Bit Vertical Resolution
    2 Channel
    External Trigger Source
    Trigger on Rising or Falling Edge at Any Voltage
    Variable Trigger Voltage on DSO channels
    10%, 50% and 90% Horizontal Trigger Position
    Auto or Normal trigger modes
    USB interface
  • Dupe! (Score:5, Informative)

    by bishr ( 262019 ) on Friday February 27, 2004 @10:48PM (#8414072)
    This was covered a few years ago; no surprise that most people forgot. The answers are mostly the same; still a good read though: http://ask.slashdot.org/article.pl?sid=01/12/07/19 1220&mode=thread [slashdot.org]
    -----
    Trogdor the Burninator!
  • by Wansu ( 846 ) on Friday February 27, 2004 @11:22PM (#8414205)

    There are a quite a few used Tektronix 465 scopes going for about $200. Check newsgroups, eBay and go to some Hamfests.
  • cheap 40 MHz scope (Score:5, Informative)

    by RadioDude ( 619834 ) on Friday February 27, 2004 @11:27PM (#8414226) Homepage
    The most common source for these type of PC-card "instruments" is National Instruments.

    If you are teaching about electronics, you would be better off buying a used Tek 475 (or similar) analog scope, you can get a very good one for $300-400. They can learn about the actual circutry, timing, measurement error, etc. without
    getting heavily into sampling theory and digitial
    signal processing.

    If you want the students to learn "the new way" of
    electronic instruments, check with National Instruments about used/traded in cards, and software; they may have an educational discount.

    There are also some "poor man's" type of scopes made of surplus parts, old TV's, etc.. that you can find in the back pages of Nuts& volts magazine; I don't recommend these if you want the students to learn what they will use in the future, in real-world engineering applications.

    Finally, there are mixed-mode instruments that are analog with analog storage, analog with digital storage, analog with digital readouts added, various standard instruments with serial or GPIB interfaces, and s/w from the mfr or 3d party for
    control and analysis.

    See if you can find on some engineer's shelf a catalog/book from Tek or HP, say, from the 1980s
    or 90's, this is about the vintage that will work and be in your price range.
  • by John Jorsett ( 171560 ) on Friday February 27, 2004 @11:28PM (#8414234)
    If you were considering PC-based scopes just to get the cost down, perhaps you might consider an actual used oscilloscope. There are many used ones for sale on eBay, and there appear to be some that would more than fit your criteria. For example, this one [ebay.com].
  • by Spikeorama ( 724224 ) on Friday February 27, 2004 @11:47PM (#8414310)
    Check out the PCI/PXI/AT/USB/PCMCIA-5102 from National Instruments. I think they're about $1200 or so and 20 MHz 2-channel 8-bit, a little more than you wanted to pay but it's good stuff.
  • by Thurn und Taxis ( 411165 ) on Saturday February 28, 2004 @01:04AM (#8414601) Homepage
    You might want to check out the boards put out by Interface [interface-jpn.com], a Japanese company. Specifically, their PAZ-3161 board [interface-jpn.com] supports up to 40 MHz sampling rate (one channel; 20 MHz if you sample both channels). Not only does this company make excellent boards (my lab has several), they provide both Windows and Linux drivers for the boards.

    I've done some preliminary work on writing signal-analyzer software for their PCI-3525 board, which I would be happy to share (it's not close to being fully-functional yet, but we've got a student who may be using these boards, so that might change soon). I'm also happy to try to adapt this code to more general use. With these boards and existing code, your task might be much easier than you originally thought. Also, their sales engineers are very willing to help solve problems. I don't know the prices on their boards (ours were donated), but they are excellent devices.
  • by Ultra64 ( 318705 ) on Saturday February 28, 2004 @02:49AM (#8415076)
    Gameboy oscilloscope [elektor-el...nics.co.uk]
  • by KC7GR ( 473279 ) on Saturday February 28, 2004 @03:30AM (#8415239) Homepage Journal
    For the amount of money you're specifying, you can easily pick up a much better built and far more versatile O-scope in the form of an older Tektronix instrument.

    In fact, that price range will easily get you a 475 or 475A, good to 200 or 250MHz, respectively. It will also put you well within reach of a nice Tektronix 7000 series benchtop 'scope, like a 7704 or even a 7904.

    No matter what you may hear, the PC was never designed to be an O-scope, and no amount of external hardware, I believe, will ever turn it into anything that can compare, in terms of value for the $$ and quality of construction, with early Tektronix hardware.

    I believe it's also EXTREMELY important to teach would-be technicians and engineers that the PC is not the be-all and end-all of test gear. Never has been, never will be. Oh, it can be useful as an instrument CONTROLLER in automated test setups, yes, but it was never intended to replace the functionality of actual made-for-purpose test equipment.

    Give your students a real education. Get a real oscilloscope.

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