JYE Tech DSO 138 review and performance testing

[fubar.gr]

I made this video review of the JYE Tech DSO 138 mini oscilloscope.

At just 100 KHz bandwidth, that means that even a 10 KHz square wave will be badly distorted, and I'm explaining why

[crispy_tofu]

Very cool. 

[Gyro]

A nice demonstration of the effect of limited bandwidth, but a little unfair on the poor little DSO138.

I built one at Christmas as a little stocking-filler present and yes it is a bit of a toy, but at least at a toy price (unlike all those pocket MP3 player based pocket DSOs!). I was wondering about doing a mini review but wasn't sure if I dare put it in the Test Equipment section. 

It's actually not that bad, yes its limited bandwidth makes it only suitable for looking at audio, 555s and power supply ripple, but the screen and UI are pretty good (quite cute) given the button limitations. The TL084 based analog section is manually switched (the s/w reads the switch positions to reflect the correct v/div and voltage readings on screen) which means that the cursor can be left on timebase most of the time.

It's useful in the same way as having a cheap DMM kicking around is useful (or a $20 LCR ESR Transistor checker?). You can float it on a supply (battery pack or isolated mains adapter) to monitor something while you're doing other stuff. The on screen readouts are quite useful.

P.S. JYE Tech have released a new 060 s/w version that corrects the time / frequency measurements to work on average input rather than zero crossing, so no missing measurements on DC coupled now. It now also has single button auto trigger level setting. Unfortunately they have also added an annoying anti piracy/cloning message (aimed at Chinese clones, primarily Saintsmart) that pops up at startup. Is nothing sacred.

Edit: It even seemed worth the effort of putting into a box...

[cdev]

The capacitor tester kit of theirs that I built is just as accurate as my UT61E and it only cost $9.

[fubar.gr]

Just a little piece of advice, before buying one, make sure it is the genuine JYE Tech one.

I first bought a Sainsmart branded one and the board was internally shorted at several places (possibly due to bad ground pour). I spent hours desoldering various parts thinking they were shorted, only to realise the short was within the board itself 

I think I will make a new video, running some more tests to figure out why it has such a small bandwidth.

@Gyro,
 That's a nice enclosure, where did you get it from?

[Gyro]

Yes, I agree (mine is a genuine one) still quite fiddly to solder, not quite sure why, I think maybe the pads are a bit small.

It's a bit surreal to see a Chinese company being ripped off by other Chinese companies, I feel sorry for them because they are obviously a small company which is trying to do good things at really sensible (low) prices. They make Manuals, schematics and f/w updates, tech notes etc freely available on their website and get ripped off. Apparently Sainsmart bought one sample from them, simply copied the PCB and put their own brand name on it, pretty blatant stuff! 

The case I used was this one...
http://cpc.farnell.com/hitaltech/dt-080-0-0-g-0/desktop-case-grey-148x87x36mm/dp/EN82833?ost=EN82833&categoryIdBox=&selectedCategoryId=&categoryName=
Hopefully there is enough manufacturer information to identify other sellers. I had to raise the slide switches (2mm headers and some vertical brass shim between the switch and the mounting holes for mechanical support. I also used buttons with long actuators (didn't bother with the reset button or trigger led). The only problem is that it isn't big enough to fit batteries in the bottom... well maybe a LiPo.

P.S. There's a mod to improve noise performance (the -050 s/w was introduced to address this, but the board mod is still valid), JYE Tech accidentally decoupled VDDA to the digital plane rather than the analog one. You can find details here:
http://forum.banggood.com/forum-topic-61279.html?page=3#quick_post

[Muxr]

I bought one of these a year ago for giggles. Will need to put it together sometimes and check it out. Thanks for the review. Neat toy.

[tino_so]

Very nice review Fubar.GR, and very nice case Gyro!

Thanks for sharing the info. I also bought a kit last year, it really sharpens your soldering skills quite a bit!

I think these type of inexpensive kits are incredibly useful as a learning tool. The manual is very clear, and it includes also a very nice schematic that would allow anyone to look under the hood and see how all is glued together.

Obviously it will not be of much use on your bench as a scope, but I think it can inspire beginners to dig deeper into their passion for electronics. One thing I have yet to try, is to update its firmware. I am sure that will be another nice little project for these long winter nights. 

[broderp]

Good God man,  Your comparison and criticism is crazy.   You are comparing a high production scope to a scope designed to teach the fundamentals of many things to the beginner, such as soldering, schematic reading and troubleshooting as well as general scope use.  For less than $25 this little thing ROCKS.   

Just like your Rigol 1052E has limitations,  so does this.  Would you use your scope in an environment that requires superior performance or more features?  Of course not.   I'd say the same thing to the $14,000.00 NASA grade scope review if they were slamming your sub-$500 scope.

The important thing is that the user recognizes their limits (for constriction) as well as knowledge and buys a scope that fits their requirements.   This would have been great to have back when I was in school.  If I had decided not to get my EE degree, then I would not have wasted a lot of cash.  It would make a nice tool or gadget for the hobbies.

BTW, you must have a knock off or old firmware.  I just bought one and not only does mine state the firmware during boot, but I do get the readings in the DC CPL mode.?

[brainwash]

I have one of those as well from a year or so ago. I use it to visualise slow-moving waveforms when I can't get a large scope (like in the shared garage). And I'm throwing it in my backpack when I'm travelling somewhere and know will be tinkering. It does the job fine as long as you have a charged battery. I 3D printed a case and added a 20-cent 9V connector to 5.5mm cable. That's the 'off' switch.

The caveat is that there are a few versions of those. I got one that's supposed to be original, but on the parts list a resistor was wrong (1.5k instead of 15k or something like this). So I replaced it with the one marked on the schematic. However, I found out later that the schematic was wrong (old?) and I was supplied the correct resistor. I think the effect is that the measured voltages are not correct, at least not for me.
Another problem is that the pin headers they use to connect the display make imperfect contact. That has been the problem so far with all displays that I've used connected via a pin header. Reseating the display board helps, for a while.
Current consumption is a bit high (~100mA) so with a typical 9V battery you might be able to get just 2h of usage.
For 12V automotive applications this is generally ok, you'll want to see dropout there and how good the filtering is, the noise is usually well below 10kHz.
There is a bug in the firmware: if you go to long time ranges (>1s) the controls will freeze until the unit acquires the data. So if you go 1s, 5s, 10s and then realized you've made a mistake you have to wait 16s + 10s + 5s to go back to the 1s time range.

I'm waiting for someone to design a BLE version that feeds data to a smartphone app. The new ESP32 looks perfect for this. There is already a product that does this (Mooshimeter) but the price of those is already into the USB scope range.

[analogix]

I'm considering this oscilloscope as I currently have no test gear apart from a Uni-T UT61E digital multimeter and need to figure out what's wrong with a synthesizer (as in musical instrument that is). I don't have many electronic projects and as this is just a hobby for me I'd rather not spend lots of money on a "professional" scope, and finding a used one at a reasonable price appears to be hard.

So, having virtually no experience with a scope from before (and not quite knowing which specs to look for), would the DSO-138 be suitable for the above use? I'll be following the schematics and using the scope to see where the signal gets broken, thereby locating the malfunctioning component(s). I guess a better questions is: in which situations is the DSO-138 NOT capable of doing the job?
Oh, I noticed from the company's website and on eBay that there's now a DSO-150 (around US$ 35 with housing) which has improvements over the DSO-138. Any opinions on that one?

[Teledog]

Just received a DSO Shell kit, including case (aka: DSO 150) from Amazon.ca, with an X1-X10 scope probe.
All SMD parts were already soldered on board, just had to do the thru-hole parts.
Firmware xxxx-053 , not going to bother upgrading to xxxx-055..unless I'm bored.
It's a nice little unit! Easier than dragging out the old CRT unit for small quick checks.
Note, the header pins on the PCB "sandwich" connections are ~1mm too long, clipped, & it makes the boards and case fit much better (still a tight fit though).
Also, you'll need a 4.5-5mm long DC plug (a short barrel DC plug doesn't work after installing the boards into the case)
and ..almost forgot..drilled a tiny hole into the 1kHz test tab..as it "needed fixin"

[cdev]

Very nice little package.

>Just received a DSO Shell kit, including case (aka: DSO 150) from Amazon.ca, with an X1-X10 scope probe.
All SMD parts were already soldered on board, just had to do the thru-hole parts.

[brainwash]

Make sure you calibrate the input and follow the instructions. As wrote above, my instructions demanded some resistor substitutions which I've ignored. With the mods in place, the voltage reading is now correct.
I think it's great for automotive work (you rarely need above 20kHz there) and can be powered in a more convenient way. I switched from a 9V NiMh rechargeable to a USB->9V converter, but, looking back, you can just buy the 5V->9V cable on aliexpress for ~4$. Having anything other than a LiPo is asking for trouble, it's always flat exactly when you need it....

[Gyro]

I just wanted to make DSO138 owners aware... JYE are in the process of updating the F/W to include triggering on slow timebases.

They've put a couple of test versions on their forum now and are asking for user test feedback before releasing the official update.

More testers needed (as I seem to only one so far!).

Forum thread:  http://www.jyetech.com/forum/viewtopic.php?f=18&t=1101&sid=1791466c2f4e49f28ae75456ed53656d  The latest version is on the second page.


P.S. Given how long they've taken to find the time to do this update, it's probably worth the effort of ensuring that it's right. I wouldn't be surprised if this is the last release they ever do.

[mikegleasonjr]

They've put a couple of test versions on their forum now and are asking for user test feedback before releasing the official update.

Thanks I tried this firmware and found a bug. I registered on their forum but I have not yet been accepted so posting here:

The trigger level readout is wrong. The value is a fraction of what it is supposed to be (seems to be tied with the sensitivity).

I would love more testers on board so that the final firmware would be released. The anti-piracy boot time is too long.

Thanks!

[Skilldibop]

Does anyone know where to find a schematic for one of these? This was noticeably missing from the kit.

I built one of these a while back and it's never worked. I've decided to revisit it and try and get to the bottom of the issue.
I fixed one issue of it blowing up 5v regulators, but now has the opposite issue of not drawing any current, bar the backlight LED despite now having stable voltages in the places I'd expect.

Their forums aren't much use and there's not much in the way of a troubleshooting guide, so fault finding is proving pretty frustrating without a schematic to know what I'm looking at! 

[Gyro]

Here you go. It's on the last page...

https://ufile.io/r3vu0


P.S. Lack of schematic probably means that you bought a non-genuine one, it was included on the JYE kit instructions.