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Which oscilloscope and/or logic analyser?

Discussion in 'General Electronics Chat' started by earckens, Aug 31, 2016.

  1. earckens

    earckens Member

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  2. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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  3. earckens

    earckens Member

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    Rise time is related to frequency? 50MHz should do I think. Accuracy: it is for hobby purposes, so nothing fancy. Sensitivity: 1mV I guess would do?
     
  4. dave

    Dave New Member

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  5. JLNY

    JLNY Active Member

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    Among USB oscilloscopes, I have used the Hantek 6022BE and the DDS120, and both of them are nearly identical as far as I can tell. I would say I slightly prefer the DDS120 simply because it is a bit smaller and only uses one USB port.

    The next model up from these would be the Hantek 6052BE and the DDS140, which are rated to 50MHz and 40MHz, respectively.

    Personally, though, I find that the triggering on both oscilloscopes can be very finicky and unreliable even at frequencies in the single MHz range, and the software interface, while good, is still kind of clunky compared to a traditional oscilloscope with knobs and buttons.

    Honestly, for the same price range as the 6052BE, unless portability or limited space are your main concerns, I might be a contrarian and recommend going for a used, traditional bench oscilloscope. Not too long ago, I was able to acquire a working Tekronix TDS 340 (100MHz, 500MS/s) for about $100, and I'm sure there are other oscilloscopes to be had in that price range that will have better features and interfaces than most USB oscilloscopes if you stake out Ebay and wait for the right opportunity.

    If that is an option, I can give recommendations as to what scopes I have used and what to look for if you want to go that route. I would actually recommend staying away from the TDS series as a first oscilloscope, as they tend to have a high rate of capacitor failure in the power supplies and can be a pain to fix.
     
    Last edited: Sep 1, 2016
  6. earckens

    earckens Member

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    JLNY thanks for the input, it is most valuable. I have been considering new versus used, and personally would prefer going with an analog oscilloscope. Just finding a good one indeed will take time, patience and careful screening. I have worked with Tektronix many years ago on a professional basis and have always been impressed with their quality.
    And yes you would do me a favour by giving your recommendations from experience.
     
  7. JLNY

    JLNY Active Member

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    My pleasure. I tend to work more on analog applications, but I also have some experience with microcontrollers, so my experience can hopefully shed some light on what you might look for. If you have professional experience, then you probably have a reasonably good sense of what you want already.

    My first oscilloscope was a Hitachi V-1100 (also sometimes called a V-1100A, although I have never heard of a V-1100B), an analog scope with 4 channels @ 100MHz. It has two channels with full functionality, and two with limited voltage sensitivity settings, and also has an on-screen display with a frequency counter and voltage/time markers. It seems to be roughly equivalent to the more common Tektronix 2200/2400-series analog scopes, but similar to the TDS series, the 2200/2400-series tend to have power supply problems. Avoid any listings that do not show the screen turned on or that show the screen being out of focus, as this tends to be a sign of failing capacitors. The main feature these lack is sample holding or storage of any kind, which can be a really nice feature to have for digital applications where you need to capture one-time signals. I got my V-1100 for about $100 about 7 years ago, and it is still working fine.

    In addition to the TDS 340 I got recently, I have used several TDS-series scopes over the years, including some of the newer color 4-channel ones. They have a really nice balance of features and a good interface, and the sampling for one-shot signals is really excellent, but they can be a real gamble on Ebay due to the aforementioned capacitor problems. If you decided to look at any of those, I would be very careful to only go for listings that show the unit on and working, preferably with an image of the "self-test passed" message on startup. I got burned a while back on an "untested" TDS 684C that was DOA.

    The HP alternative to the TDS line is the HP 54000 line. It has quite a few entries, some of which are more digital-focused and others which are more like traditional analog scopes, so you can look around at what's out there. A co-worker of mine has one (a 54600B, IIRC), and he has had no problems with it as far as I know. AFAIK, I think they have a slightly better track record for reliability, but the HP name can sometimes raise the price.

    The only other scope I have used, and which I don't recommend AT ALL, was an old boat-anchor of an HP 140A, which is actually a general-purpose display mainframe that can take various kinds of plug-ins for either oscilloscopes, spectrum analyzers, Time-Domain Reflectometers, and several others. I bought it so that I could use the scope plugins to calibrate the display unit in my spectrum analyzer, and as a spare display mainframe in case my main one breaks down (the HP 140/141 mainframes are very cranky, old units, so they tend to pop fuses and transistors in the power supply from time to time). The massive round display is actually surprisingly nice to look at once you calibrate the power supply and the focusing, but the limited frequency range will likely exclude most "boat-anchors" from your search. I have never actually tried using it in my 141T storage mainframe to see how well it works as an analog storage scope, but if my experience with the spectrum analyzer is anything to go by, analog storage can be extremely finicky to get just right so that the signal "sticks" without being too bright and blooming out the screen.

    I'm sure others on this forum can give their reference points on what scopes they have used. Tektronix and HP tend to get a lot of attention, but I would be interested to hear what experiences folks have had with the more "off-brand" scopes like my Hitachi.
     
    Last edited: Sep 1, 2016
  8. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    I have an analog HP 200MHz scope and an old TDS digital 60MHz scope.

    For anything < 60 MHz, the TDS is my goto scope, with all the automated measurements that make it worthwhile. If you are familiar with aliasing and sample rates, this speeds up learning curve. Triggering is excellent. Calibration is auto. No problems in 20yrs.

    I like LeCroy for nanosecond and automated measurements.

    Rise time is 1/3 of 1/f bandwidth.
     
  9. spec

    spec Well-Known Member Most Helpful Member

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    I can recommend the Tektronix 2235A and they are available for a reasonable price second hand.

    spec
     
    Last edited: Sep 2, 2016
  10. fourtytwo

    fourtytwo Member

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    Hi I recently bought an Owon VDS1022 and so far am very pleased with it, one thing to watch that's not in the spec is it goes into auto mode above 50mS/div and that stops you single shotting slow events. Otherwise the triggering is excellent as I believe it's done in hardware. Although it has two USB plugs on my Laptop it runs happily on one. Noise not bad, Isolation excellent but again using a LT on batteries don't need it. OK you can push it to the risetime limit in some circumstances and it would be no good for debugging very fast data buses (>66Mhz) and it's a bit dodgy on very fast power mosfet switching. I believe streets ahead of the Hantek products that rumor has it are based on the doddery old FX2 USB chip. The Owon has an Sparten XC3S200A and M3U156 32 bit arm processor so a bit more potent on board processing. There's a few other wrinkles when compared with lab type scopes costing thousands but not so significant I can remember them :) I think there's a review I remember reading out on the web somewhere.
     
  11. earckens

    earckens Member

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    Thanks for all your inputs; it looks like I will be patiently searching for a used Tektronix (JNLY and spec), and if I do not find any in the foreseeable future go with fourtytwo's advice.
     
  12. Rich D.

    Rich D. Member

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    I am searching for a scope, and I found this pretty affordable digital scope. Don't know your budget but this is not too crazy, $300. http://www.mcmelectronics.com/product/TENMA-72-2580-/72-2580
    Some basic specs: only 3" deep, comes with 2 probes, pretty big 8" screen, up to 30MHz and 10,000 sample memory. Only does 5mV per division though.

    I haven't decided for sure yet, for the same price this one is 50 MHz and goes to 2mV per division. Slightly smaller screen and a much deeper box. http://www.mcmelectronics.com/product/GW-INSTEK-GDS-1052-U-/72-11990
     
  13. earckens

    earckens Member

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    The second offering looks more interesting; however I am not decided yet on whether to buy good used (contradictio in terminis?) and new.. I am not pressed, so time will tell.
     
  14. Rich D.

    Rich D. Member

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    That's cool. The more info you have and the more choices you have, the better your decision will be.

    For me, there are some really good bargains with newer technology, I could never go back to the old analog scopes. I tried at work recently to look at the two phases of a stepper motor, only to realize that the CRT type scopes alternate between multiple traces (unless they have a chopper mode), so there was no possible way to see both waveforms at the same exact time. That's why I'm looking into a scope for work. I use a digital at home.
     
  15. schmitt trigger

    schmitt trigger Active Member

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    I use a Saleae logic analyzer. The hardware is very well made and the software is so intuitive and straightforward to use, that you'll be doing digital analyzes a couple of minutes after you plug the unit.

    There are many Ebay knockoffs of the Saleae unit, at perhaps 1/10 of the price. But I decided to by the legitimate unit and don't regret my decision.
     
  16. JLNY

    JLNY Active Member

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    What kind of scope was it that it didn't even have a chop mode? Pretty much all of the analog scopes I have ever seen do have a chop mode. I mean, even my ancient 140A has a chop mode, and it's got vacuum tubes in it!
     
  17. Rich D.

    Rich D. Member

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    CORRECTIONS:
    If anyone cares, this above statement by me is not true. Upon further research, the Instek model is only about 5.5" deep (140mm). The MCM website has the wrong dimensions.

    B&K 2120B (30MHz) DOES have a chop mode actually, but since I was looking at PWM waveforms from current regulated motor drivers I couldn't get a clean picture of the pulses of the driver outputs. Since these were not repetitive waveforms from a single step of the motor accelerating then stopping, the signals of interest flash on the screen and just as quickly evaporate. If it had phosphor persistence, maybe I could have seen them. I know this is a very specific application, but there are times when a digital scope outshines an analog scope. With the price of them being obtainable from all but the very budget minded, why deal with focusing those blurry beams?
     
  18. JLNY

    JLNY Active Member

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    This is very true, and that is probably the main advantage of DSOs over analog scopes. The inability of analog scopes to capture non-repetitive signals is a real issue, especially in digital applications, which is why I specifically mentioned it as a drawback of things like the Tek 2200/2400 scopes.

    Analog storage displays can alleviate this issue in some applications, but analog storage scopes come with their own set of challenges, and are difficult to use in comparison. I also find that storage displays really need to be properly calibrated in order to function correctly. These days, analog storage is often more trouble that it is worth compared to digital storage IMO.
     
  19. spec

    spec Well-Known Member Most Helpful Member

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    All quite true, which leads to the logical conclusion that, just like an analog and a digital multimeter are nice to have, so are a traditional scope and a digital storage scope. As you say analogue storage scopes were a bit awkward to use.

    spec
     
  20. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    DSO prices are slightly proportional to BW
     
  21. StellarRat

    StellarRat Member

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    You didn't specify a price range. I bought a Rigol 1054Z for around $400 on my brother's recommendation (he works at an engineering firm.) It seems capable of a LOT. I will be the first to admit that I haven't used all the features, but for the stuff I have done it seems very adequate. I had a USB hobby one before that, but there really is no comparison in the ease of use, features, etc... Looking back I wish I had just bought a standalone to begin with.
     
    Last edited: Sep 26, 2016

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