We live in a time where there’s virtually no excuse not to have some kind of oscilloscope. As [IMSAI Guy] shows in a recent video, for what you might expect to pay for a decent meter, you can now get one that includes a scope. There are several options out there but it is hard to know how much to spend to get the best possible product. The Zoyi ZT-702S that he looks at costs under $80. But is it worth it?
Scopes that connect to your PC are often very inexpensive. You can also find little toy scopes that use a microcontroller and a little LCD screen. Even though the specs on these are usually appalling, they will still let you visualize what’s happening in a circuit. Sure, you want an expensive bench scope with lots of channels sometimes, but often, you just need to see a signal in broad strokes. Having a scope and a meter together is very handy.
The little meter claims 10 MHz bandwidth and 48 megasamples per second in scope mode. The meter claims true RMS and 9999 counts. The internal battery charges from USB-C. As you might expect, the meter portion works well enough for a basic meter. The scope reacts well up to 5 MHz. It isn’t necessarily the best scope in the world, but for $80 it seemed quite adequate. The probe compensation wasn’t able to quite make a square wave square, but you still got the idea.
As commenters on the video pointed out, there is a newer model that has two channels (at a slightly higher price tag). They also point out that there are dozens of similar devices at different price points, and everyone has their favorite.
If you have hobby-level cash, we’d suggest a higher-end scope meter like an OWON or Hantek since the professional brands are still very expensive. We wonder what the designer of 1983’s Pocket-O-Scope would think of these modern devices.
Price still separates toys from instruments
I once read an anecdote about how someone like Eric Clapton decided to play along with an opening act. They didn’t have a great guitar, but it turns out an expert is still an expert even on a mediocre instrument.
That isn’t to say an expert isn’t even better on a truly great instrument, be it a musical one or a measurement one, but sometimes you use what you have and don’t look down your nose at a tool that works.
The most realistic anecdote Ive heard is that most players just “sound” like their own style regardless of numerous overvalued factors. Sure Hendrix on a cello would sound different than guitar, but the real substance is Jimmy himself. No gear maketh a musician better except their own faculties and body.
My inner child needs toys, so what?
There’s a vast amount of problems where any scope or any DMM is good enough – I have a Tek scope & an Agilent DMM on the bench but I also have a ton of $10 DMM’s that live in drawers, tool boxes, car glove boxes where they are more than good enough for checking if electrons are doing roughly what they should be.
Likewise a cheap “toy” scope is more than good enough to see if a signal is doing roughly what’s expected – is a serial or I2C line sending data or silent, are pulses from an ABS or crank sensor there or not, that sort of thing – I wouldn’t want a 5k scope in my garage, but I can find a ton of uses for a $20 toy one.
Phyzzi’s story is also true – buying the expensive guitar doesn’t make you Eric Clapton.
You can do a lot with 10MHz bandwidth and being battery powered and not earth ground referenced you don’t need to worry about putting the the meter ground lead on a live connection. Saves you from having to buy a differential probe or separation transformer for your oscilloscope or DUT.
I think on AdriansDigitalBasement he said that the trigger doesn’t always work, so it may not be great for timing critical measurements.
There is now also a dual channel version Zoyi ZT-703S for around 100 Euro (with 2 probes) on Ali.
EEVblog 1597 does a unpack / test on it.
“But it’s not a proper oscilloscope like an £2k Agilent”. That’s irrelevant, the only relevant question is whether you understand the capability of what you buy and whether it suits your needs.
I sold my old Fluke 97 scopemeter which was starting having problems for £150, and spent £60 on a new Zeewei DSO3D12, and do not regret it. I had never used the Fluke anywhere near it’s 50 MHz capability anyway, and the cheap Zeewei works great for what it is and is great value. Also has colour screen and built in rechargeable battery, so way more portable too.
3.2 inch screen running 10$ DSO kit firmware I guess it works, still use my (free, but 1988) Kenwood CS-8010 but thats just me
I just don’t know when I see something thats a 200khz kit running the same firmware on something to claim 120Mhz, cost seems irrelevant, it probally picks up a 3.5Mhz color burst signal just as well, as in a worthless blur
I have both an old Tektronix analog ‘scope and a little Xprotolab scope-on-a-DIP-module — exactly the sort of microcontroller and screen called a toy — and the latter got a lot more use just because it was less hassle to set up.
(I built a little carrier board for the Xprotolab to turn it into a Eurorack module, so it could always show waveforms of my musical stuff — until the OLED screen abruptly burned out. Unfortunately you can’t buy them assembled anymore, and I haven’t gotten up the nerve to try to either replace the OLED or build a kit version with all the SMD soldering.)
About two months ago I got a similar model, but it’s a Zotek 702S instead. Same number, different name. And the brand name is nowhere on its box. Maybe it’s a Chinese rip-off of a Chinese product?
Anyhow, it’s been getting a lot of use, especially since I’ve been working with 8-bit microprocessor stuff lately. The first thing I did with it was use its frequency counter to find that not only was a crystal not working, but it was oscillating at 100Khz without the 4MHz crystal.
It’s been well worth the 80 bucks, and I haven’t even tried to use it as a meter yet.
Dave Jones of EEVblog fame has revirwed it (and tore it down) as well a few months/a year ago. Both units. I got the dual one too. i love it, even thoigh I hatdly use it. It sits in my work bag though, so always have it with me. Thaymt alone is a great feat.
The best meter is the one you have with you :)
Now if only some great hackers start making/porting some great foss software too it … (which reminds me to check for firmware update again).
Dave Jones of EEVblog is one of those “if it’s not worth 2 grand, I’ve already made up my mind that it’s garbage before I’ve even had a look at it”.
A lot of us are not pro and just need something cheap and cheerful to do the odd repair.
If your job is to test UHF on a daily basis, of course this is not for you, but if like me you never go beyond occasional HF work, then why would you spend more on something you don’t actually need.
So I agree with you and I’m satisfied with my cheap Zeewei. It doubles as a multimeter too. The last time I needed to check something, I used it instead of digging out the Fluke 97 because it was just there on the table and did the job just fine.
I just saw this and I was like “wow, I just the same exact thing except it says Zotek”
It’s been good to me so far, as my inexpert usage has gone.
I very much like the Kerry Wong review of the Hantek and Owon. Both dual channel scopes. With a 2 channel scope, you can compare the input and output of a circuit with each other, and I would consider 2 channels an minimum. A quick check, the Owon HSD242 can be bought in the Netherlands for EUR130. And with it’s claimed 40MHz bandwidth it’s fairly decent for the price. This pricepoint is apparrently the border between toys and usable equipment. An instant thumbs down for the claimed 10MHz bandwidth, while it can’t even display a sinewave of that frequency without serious “wobbling” (@06:55). I don’t care much what the actual bandwidth is, but if the manufacturers are lying in their basic specifications, then it is an instant thumbsdown and I will not ever buy it. It is the only way to force manufacturers to stop lying, and comparing stuff is difficult enough already when the gadgets meet their specs. For this reason I will never buy a “fnirsi” gadget. If you can’t trust what you see on the screen, you’re constantly second guessing your instrument instead of focussing on your project.
I still don’t know what to think about the “DSO Shell” a.k.a “DSO 150”. It is also clearly a toy with it’s 200kHz bandwidth and very limited triggering. I bought one just for fun (Also have Siglent SDS1104X-E) DSO-Shell is mostly lacking in trigger stability and noise. It’s quite bad as a toy scope, but even then, it’s still a fairly decent development board for an STM32 with TFT. It also gains some extra points for the availability of the schematic and partially open sourced software. (It looks like you can tweak the GUI, but the actual sampling is done by a pre-compiled library). I have not looked deeper into the software, but this probably makes it relatively easy to use it as a permanent display in some custom / diy / hacked instrument.
The Owon handhelds are great: they basically all exceed their stated bandwidth if you’re considering the 3 dB point. They’ve also dropped in price significantly over time, so you don’t have to just look at the low end: on Banggood they’re like ~115/150/175/225 for the 40/70/100/200M versions.
Working with digital/VHF signals you’d be hard-pressed to need much more than the 200M. Honestly, the price increases for the features/bandwidth are reasonable enough it’d be hard for me to say “this is the sweet spot” other than just going straight for the 200M.
I have the 70 MHz Owon and I quite like it. Lots of great functionality for the price. The built-in function generator was probably what drove me to pull the trigger on it. For higher freq stuff, I have a couple benchtop scopes. But, the usefulness of portability/battery operation (with a single 18650 that can be easily swapped) can not be overstated, in my mind.
IMSAI Guy is putting out some great content (well he just did a bunch of radio stuff that I wasn’t interested in but…) most all of his stuff is worth a watch. He’s a good teacher to boot.
You could always go with this…
https://www.flickr.com/photos/31767011@N02/8679905826
I still occasionally use my GBDSO (Gameboy Digital Sampling Oscilloscope ;)). I also have a Siglent SDS1104X-E.
Well, the Siglent has a carrying handle and I would consider it portable, especially compared to my old Philips analog oscilloscopes, which also feature a handle. But, it does not have a battery.
On the other hand, the GBDSO has a battery, but has only 100KHz bandwidth and a 1 Msps rate.
I find that for things that I do ‘out in the field’, where I need a scope but don’t have power available (and often limited space), the GBDSO has always been enough for me. No need for anything more powerful. The original Gameboy does not have a backlight, but I find that it works perfectly with a Gameboy Advance SP, which does have a backlight (but a smaller screen).
For real lab work, electronics debugging, microcontrollers, repairing old computers, etc. I really do need the higher bandwidth of the Siglent. Signals are generally in the range of 8MHz up to 100MHz.
These kind of scopes with 5MHz or so bandwidth are of limited use in a lab, if you’re working with microcontrollers and e.g. video circuits. They cannot replace a serious scope, and imo they are a waste of money. Already useless for repairing e.g. a Commodore Amiga, which runs at 14MHz. 20MHz bandwidth is the minimum, I would say.
So don’t buy a scope like this for your electronics lab because if things get serious, you’ll buy a higher-bandwidth scope anyway and you would have wasted your money. But as a second scope, for portability and occasional work outside the lab, e.g. quick troubleshooting, they are great.
But I get around with my 100KHz GBDSO for those things. If it ever breaks, I might buy a new one, but would probably not spend more than $50 or so on it. And it must be battery-operated and be able to run for a few hours. Maybe a Fnirsi DSO153, which also features a signal generator.
GBDSO is on Github nowasays: https://github.com/pyroesp/GBDSO
The article can be downloaded here: https://elektrotanya.com/gbdso_gameboy-digital-sampling-oscilloscope.pdf/download.html
When you just need to view and not measure (accurately)
I have been working on a lot of motion control lately, I just need to see if I am getting step pulses or not, if so, roughly how fast. Sometimes I need to know roughly the pulse width.
I have high end scopes, but taking a simple device like this to the equipment is easier for me than taking a scope, even the simple DHO800, I rather take this first, if I need dive deeper, then a good scope.
i used to have a portable scope like this and i hated the buttons. i’m sure this one is better than the one i had, but the buttons were just plain crappy. i realized that even the cheap bench scopes like the ubiquitous siglent have like 7 dedicated knobs instead of making you go through a bunch of nested menus with mushy buttons, and i haven’t looked back. i was eager to get rid of that button scope.
of course, it helps that just about every time i really need a scope, i’m at my workbench. even my multimeter doesn’t leave the bench often and making a bench-mount pocket for that was a huge upgrade.
Right on. I’d love to see one of these cheap handheld scopes with a few clicky encoders rather than just buttons. The interface makes all the difference.