Digital Oscilloscope Does Its Best Analog Impression

Do you ever find yourself yearning for the days before digital storage oscilloscopes (DSOs)? Where even the basic scopes commanded four figures, and came in a bench-dominating form factor? No, of course you don’t. The DSO is a wonder of modern technology: for a couple hundred bucks you can have capabilities that previously would have been outside the reach of hobbyists, all in a package that’s small enough to fit on even the most cramped workbenches.

Which is why the good folks of the EEVblog forums are so confused about the OWON AS101, a modern digital oscilloscope that’s designed to look and operate like the analog CRT monsters of old. Despite the 3.7 inch LCD, users are treated to the classic analog scope look, and the switches and knobs on the front should trigger a wave of nostalgia for hackers of a certain age.

But this isn’t just some “retro” look-alike, OWON is committed to delivering on that analog experience by taking away all those modern digital features we’ve become so dependant on. This single-channel scope can’t save data to USB, doesn’t have any sort of protocol decoding capabilities, and forget about automatic…well, anything. It’s even limited to 20 MHz, just like the old-school CRT scopes that you pick up for a song at any swap meet. All for the low, low, price of $150 USD from the usual importers.

In the EEVblog thread, the best idea anyone can come up with is that the OWON AS101 is designed for educational markets in developing countries, where outdated equipment is so common that there may actually be a need for faux-analog oscilloscopes to match what’s already in use. These new-manufactured “analog” trainers can be used to get students ready for a professional life of using antiquated technology. It’s hard to believe, but sometimes we can forget how fortunate many of us are to have easy access to cheap tools and equipment.

Even still, when you can get a pocket-sized 10 MHz DSO for around $50, it’s difficult to imagine how this analog-digital hybrid could possibly attract any takers at 3x times the price. If any of our readers would care to shed some light on this unusual piece of gear, we’d love to hear it.

[Thanks to David for the tip.]

48 thoughts on “Digital Oscilloscope Does Its Best Analog Impression

  1. As said… Looks as usefull(less) as cheap chinese pocket oscilloscopes. But unlike them it’s big and unisolated (no battery power), which might cause troubles when used for education of students unaware of ground loops. Maybe someone will figure out how to flash it with custom firmware or something…

        1. Truth be told, I have not seen a green-phosphor ‘scope since my Tek 545, longer ago than I care to admit. And before that, my even older Heathkit. They’ve all been the blue-green since. Well, except for that LeCroy, with its gorgeous amber CRT.

          1. Had on old tek scope that had a genuine *blue* phosphor screen. Looked exceptionally cool, but a small screen (5″ circular) and weighed a ton. Valves and linear power supplies with proper iron transformers. Dual trace too (real dual trace, not chop or alt mode single trace).

            I’ve used those $50 handheld “scopes” and they are truly pathetic. The *only* thing going for them is their size (as in portability, not so good if you don’t want them to go skidding to the side when you let them go). At least this thing has real knobs that you can turn and twist. Now, just make it open source…

        2. Depends on your traditions. P1 and P2 phosphors were both brilliant green, and these were the dominant phosphors for general-purpose oscilloscopes in the 1940s and 50s, and well into the 60s. For applications needing long persistence, such as RADAR and spectrum analysis, P7 had a blue-white phosphor with yellow-green persistence, and P11 was a purple-blue phosphor with very fast response and decay, used for high-speed single-shot signal applications and flying spot scanners. Then came P31, which is a faster and more efficient blue-green phosphor, and replaced P1 and P2 in most oscilloscopes in the 1960s – 80s.

  2. In an ed environment, simple is often the way to go. For elementary exercises, like phase shift, decay curves for capacitors and inductors, and the like, the basic models have the advantage of not overwhelming students. They get a feel for what the timebase and input gain settings are for, trigger level, and so on, without confusing menus and features that will distract from the basic goal.

    This is a bit TOO basic, in my opinion, though. Two channels are dead necessary, and a single trace capture or screen ‘hold’ would make this a useful tool, even without the USB and decoders. Many, especially lower end, DSO’s have such involved interfaces, and such lag between the controls and the display, that they are unusable by someone not already intimately familiar with the concepts.

  3. A place where I worked 20 years ago, had a digital Tektronix o-scope. (Well, they had a number of various Tek scopes)
    I was unable to use it when I sat down at the bench where it was located. There was nothing “intuitive” about the controls from an analog perspective. I have seen better Teks since then, I don’t understand why that one was ever built…
    I own a couple of digital scopes (Nicolet) that are even older, but their controls and help menus make them easy to use.

      1. I feel like there are some basic UI design choices that vary heavily between manufacturers, and once you like one it’s hard to switch. I love my lecroys and am the only person at work who uses them regularly. Everyone else loves Tek. Our Agilent sits largely unused because people think it’s weird, and our Yokogawa was given away because everyone hated its UI so much. We likewise have one other person who loves Rohde & Schwartz scopes, so he has both of those on his bench, and all the rest of us find them confusing. In almost every case, those preferences are determined by the equipment we originally learned on.

  4. There are a lot of old electro-mechanical devices out there that need regular adjustment, with an old tektronix scope to display waveforms and a laminated instruction sheet on how to adjust the machine, given the waveform on the display. The machine and its instruction sheet are still good decades later, but where do you get a replacement scope? All those fancy features just get in the way.

    Depending on the task at hand this scope is perfectly adequate and may even be the best tool for the job. Clearly something is driving its demand.

  5. I would *love* to get my hands on a new scope that was as intuitive to use and responsive as a classic 80s-era Tek or even my elderly hybrid LeCroy 9400 (though even it has its issues).

    Modern scopes have controls that are so overloaded with functions that it’s a major cognitive chore to do even basic tasks. Buttons are all mushy rubber and all feel the same. Encoders replaced potentiometers and detented knobs with real endstops. And don’t get me started about having to stab a touchscreen to get something done.

    On a modern scope you push a button, and it may or may not have the function it had two minutes ago, and it may or may not have some non-deterministic delay before it does anything, and it may send the device spiraling into a mode that takes a few more stabs to back out of.

    You get the distinct sense that the people who design the user interfaces for these things don’t actually use them very much.

    I for one think the sentiment (if not the execution) of this is a step in the right direction.

      1. I’d rather fewer features than more if I had a room full of kids trying to follow along. How many times have you accidentally set some mode or tweaked some paramer somewhere down the deep menu tree on a full-features DSO and had to hunt for it to undo it. Now imagine trying to undo 20 different such accidents made by kids who had never touched a scope before this class and had not yet acquired the lingo or the intuition to even describe what’s wrong with what their display shows vs. the teacher’s. If every setting has a visible knob and there is zero hidden state this problem gets easier. If there are only a half dozen knobs it gets easier still. I imagine that’s what they’re after.

        It’s like the idea of simplified phones for kids and old people, except applied to a scope.

    1. I love my stack of LeCroy 94xx’s (50, 14, and 24) but their encoders go out too and wowie is that annoying. Luckily for me, scopes with broken front panels are even more dirt cheap, and GPIB control isn’t really that difficult to implement.

    2. I also prefer analog scopes.

      The action of the old scopes is, in a sense, “visceral”. You click the timebase to the right and the signal is instantly expanded, click to the left and it is compressed. Modern scopes use screen pokes and auto ranging, which severs that connection between the user and the display.

      All the extra functionality (protocol decoding, for example) is good, but in the race to fit as much functionality as possible, the makers have sacrificed a lot of user friendliness.

  6. Would be cool if it went higher than 20MHz. But if it’s limited to that, why wouldn’t I just go and get an actual retro one for way less and have a real CRT to boot? Seems like that would be better in every way for anyone who might want this.

    1. Except that you can not get a purchase order for a bunch of old outdated (no matter how good and useful teaching tools they are. ) Oscilloscopes. Schools and other organizations live and die by multiple purchases, and purchase orders,
      so this fills a real need.
      Laurin WB4IVG

      1. True.

        The bureaucrats and business people are literally destroying our world with all the resources that are directed to a hole in the ground because of their paperwork requirements. Each and every one of them should take a long hard look at themselves and realize that they are the problem.

      1. This is what I got by Googling it – perhaps you should take your own advice.

        Digital Sampling Oscilloscope, samples measurements and displays or stores them
        Digital storage oscilloscope, which stores and analyses the signal digitally
        Dynamic Shared Object, in computing
        Drakensang Online, the online computer game

  7. Nope. Does not act like an analog ‘scope. He doesn’t show what happens if you disconnect the input signal. On an analog scope, the trace would either disappear, if triggering in “normal” mode) or go flatline (if in “auto” mode). I’m betting that in “normal” mode, this just holds the last triggered waveform. So if students are getting used to having the last waveform just stick around forever, they’re going to run into trouble if they have to use an analog ‘scope in the field.

    In the early days of digital ‘scopes, Tektronix developed something called a “digital phosphor” display, which is a digital storage ‘scope that acts like a variable-persistence analog storage CRT – waveforms fade away gradually, rather than showing just the most recent samples. They’re still making these, with their “DPO” series. I doubt many people would know why, these days. The reason was that on analog ‘scopes (whether variable-persistence storage type or just plain CRT), if you had a glitch that happened now and then, let’s say a pulse that happened once every few seconds, you could see it on an analog CRT due to both persistence of the phosphor and persistence of vision. With ordinary digital storage ‘scopes, glitches might show up between screen refresh cycles, missing infrequent glitches. This was a distinct advantage of analog ‘scopes, and one of the few things that kept people buying analog oscilloscopes, and since Tek was phasing out all of their analog models, they didn’t want to lose market share to companies still doing analog, and this was what they came up with, and it was considered the best of both worlds. Of course, with most modern ‘scopes, the triggering modes let you catch things like this, but you have to know what you’re looking for.

    1. Bingo — this is why I keep my LeCroy and Tektronix 545A around analog scopes around. Years ago working a consulting job involving a black-box communications bus, and scant documentation in German (I took high school Spanish) I had no clue what was going on and triggering was a challenge. What does the waveform look like? What do I trigger on? There are also no sampling artifacts and other vagaries with my analog scopes; nothing between zero and one was lost. And bus noise was easily confused with desired signals until I knew what data was being transmitted. Oh, and AC slave power was transmitted over the same 2-wire communications bus in a distributed ordnance system.

      The time saved by using the analog scopes to see the actual waveforms with very little machine distortion was what made profit possible.

      I did buy a Link Instruments DSO to capture the waveforms after I figured out what was going on; Polaroid film for my Tektronix Scope Camera was elusive, and the bandwidth was not as great as my DSO. The LeCroy was faster (100MHz) than both, but I had no camera for that one. Digital waveform capture was perfect. BTW, Link Instruments makes nice hardware (no cheapie Chinese parts of questionable origin), so check them out (and no I am not affiliated with them in any way.)

      The only downside to the DSO was it interfaced with a parallel port, and even with a serial to USB converter from Link Instruments, I ultimately ran into driver issues in recent windows versions. I can now run it only in an XP virtual machine. A perfect DSO that is practically useless because operating systems changed. And it was not cheap. The LeCroy was even more expensive, but suffers no software issues. Both were more than paid for by the task at hand.

      I prefer the green trace, too. The natural color (without the filter) tends to be bluish on my 545A, but that green filter just feels like home. Just for reference, my 545A is a couple of years younger than me and my 575 curve tracer is about my age. Yeah, they’re OLD.

  8. There is some irony in the fact that I reach for my cheap(ish) USB scope before the fancy state of the art Tek scope because it’s much more intuitive and way easier to capture traces that I inevitably have to email out..

  9. I imagine that it’s merely a PSU display board with some ADC/GPIO connections broke out to potentiometers, switches, etc. A teardown would be “educational”. Perhaps a firmware hack along with a Battery power upgrade would make it more reliable too. A lower pricepoint would make it more desirable for hacking, I agree it’s an over priced, low feature not-so-DSO.

  10. Old scope: turn switch wait half a minute to heat up, then use it
    New scope: booting… requester… menu… hitting the wrong “button” on the overly sensitive touch screen filled with too many tiny squares representing buttons.
    The scope in this article: turn on switch and use it without significant delay

    I can see the appeal!

    1. It’s funny – in the 1990s, makers of digital scopes were working hard to give analog scope users everything they already had, so they wouldn’t lose market share to makers of cheap analog scopes. Now, digital scope makers are coming up with scopes that behave like analog scopes, so they don’t lose market share to 40-year-old Teks and HPs! I STILL don’t have a DSO, although I have an embarrassing number of analog scopes of every size and capability. This came about because I found myself with no oscilloscope at all a few years ago, and went shopping for DSOs. Finding them all either too expensive or too mickey-mouse, I went looking for used scopes instead. This led to me buying pretty much every model of scope I had wanted but could not afford when they were new.

      I must be younger than some here, though, since all of mine are all solid-state except for the CRT, and except for one (early Tek 321A) with a Nuvistor front-end. Not interested in the 545 or its contemporaries – I had to lug them up and down stairs too many times in the Air Force. There was a reason they had TWO handles on top.

  11. You can have all that shiny stuff on this basic scope!

    Poor Man’s Storage Scope; With nothing more than an oscilloscope [such as this one], a video camera nd a VCR [or maybe an old smartphone and a custom 3d-printed mount], hobbyists can have many of the advantages of fancy logic analyzers and digital storate scopes.

    Build the Quad Tracer; Gain the advantages of an expensive multi-trace oscilloscope at a fraction of the cost. It displays three additional traces on any single- or dual-trace oscilloscope.

    Build a Signature Tracer; Improve the troubleshooting capabilities of your oscilloscope

    If you really hate yourself.

    1. Signature analyzers were “the new best thing” for about a week in the 1970s. These were supposed to replace training of technicians; devices just ran self tests and told the repairman what module to replace. Of course, not all electronic devices were computer-controlled, so signature analyzers generated test vectors, and the service manual contained long sections of signature tables, indicating the failure. Then they discovered that there was just no way to predict every single possible failure mode for a device, resulting most failures returning “unknown failure” results, leaving the untrained repairmen with nothing to do but call tech support.

  12. Oh I want to tear one down and start on a new bit of firmware for it… Some screen measurement, capture, better triggering, maybe an FFT, expanded sample memory… If I didn’t have a job… *sigh*

  13. “These new-manufactured “analog” trainers can be used to get students ready to a professional life of using antiquated technology. It’s hard to believe, but sometimes we can forget how fortunate many of us are to have easy access to cheap tools and equipment.”

    now that’s condescending. pretty high horse you have there sir.

    please explain us how inferior we are, and how fortunate you are

        1. Well, my point was that I can be still be fortunate without having a digital oscilloscope, despite the implication in the article, but I don’t want to leave you in suspense:
          1) Tek 7704A with 2x 7A26 dual-channel amplifiers, 7A13 differential amplifier, and 7B85 timebase. Nope, didn’t get a 7104; those were just a little too bleeding-edge for me, and the microchannel faceplate was prone to intensity variations across the screen; the 7704A is a solid workhorse that can handle anything I want to look at in the time domain.
          2) HP 1726a 275 MHz portable with triple timebase (main plus two delayed timebases for making differential time measurements). This was the pinnacle of the HP’s 1700 portable series.
          3) HP 1741A 100 MHz portable with variable persistence storage. Just because. I usually shy away from storage scopes, because their CRTs are easily burned-in, but for capturing single events, they can’t be beat. I got lucky; the CRT on this doesn’t have any bad burn-ins.

          Those are the high-performance ones. I also have some niche instruments:
          3) Sonly/Tek 323 and 326 battery-powered scopes. The 323, in addition to being an ultra-portable scope (for its day), is also a companion display unit to the Tek 1401A spectrum analyzer. However, this was not a particularly high performance SA – it was made for the cable TV industry, and it topped-out at 500 MHz, and the resolution bandwidth wasn’t much to speak of, so I haven’t looked for one of those.
          4) Tek 321A. The first battery-powered Tektronix scope. All solid-state except the CRT, which was also a first for Tek (at least the newer models – the older ones used a Nuvistor in the vertical preamp stage.)
          5) HP 140S spectrum analyzer mainframe with P7 phosphor, with 8554 RF (100 kHz to 1250 MHz) and 8552b IF sections. Not technically an oscilloscope, but it was just a minor variation on the HP 140A, adapted for use with spectrum analyzer plug-ins. It can still use standard 1400-series plugins, if I could find any, but then, as an oscilloscope it wasn’t anything special, anyway.
          6) Tek 432. This was an oddball instrument – electrically it was nearly identical to the low-cost T900 series, but while the T900s had a form factor similar to the one in the article, this was set up horizontally, allowing stacking with other instruments. Plus, the T900s had really ugly plastic cases, which caused some of us to refer to them as “Electroluxes”. But the really special feature of the 432 was the extra range on the horizontal magnification. While many analog scopes had 10x horizontal magnifiers, the 432 had magnification up to 50x in 1-2-5 steps, and this was coupled to the sweep speed switch in a pull-to-turn way that made it function like a poor man’s delayed sweep system. This made this one of my favorite low-performance scopes.

          All of these are fully working except the 323 and 321A, both of which have minor problems that I just haven’t gotten around to fixing, and the 432, which was in a flood, and may never work again. The 321A I’m considering converting from germanium to silicon transistors, and the 323 and 326 from NiCd to Li-ion batteries. We’ll see.

  14. I like the quick simplicity of the old fashioned controls but I also like the nifty modern features for doing more advanced stuff. I have to agree though that going totally retro has to be an idiot move. Even if the students are being trained for a life with antiques, I would point out that adding SOME modern features in these scopes would make them desirable sought-out improvements for out in the field.

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