$25 Color Oscilloscope! The Incredible DSO138 (4K)

I wish I had this when I was learning electronics in high school. After the resistor, capacitor, and inductor basics, oscilloscopes are almost indispensable in next stage electronics. Most electronic equipment contains oscillators, from clocks to computers, and an o-scope is a critical diagnostic tool.
Video of it in use with joule thief and frequency generator: • Using The $25 DSO138 O...
$23 Fnirsi-138 Pro Vs. $25 DSO138 Oscilloscopes • $23 Fnirsi-138 Pro Vs....
This one cost about $25 with the case (but I'd skip the case next time). It has many of the functions of my $600 scope.
Personal Observations: Its upper limit is 500KHz, but is better starting at 400KHz down. It is not automatic, you have to be close with the timing before it syncs and gives good detail data.
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INFO I HAVE SCRAPED TOGETHER. Supplied "as is". You take all the risks for how you use it!
OPERATIONS:
[SEL] button: Selects parameter to change. Selected parameter will be highlighted blue. Press on [+] or [-] button to change parameters options. Press & hold SEL to save settings.
[OK] button. Quick press: Run / Stop. Long press: detail measure on/off.
[CPL] switch: Sets coupling to GND, AC, DC. If GND, scope input is isolated from input and connected to ground (0V input).
[SEN1] & [SEN2] switch: Adjusts sensitivity. The [SEN1] X [SEN2] = actual sensitivity. Displayed at panel lower-left corner.
[RESET] button: Resets system & reboots the oscilloscope.
TRIGGERS / MODES
[AUTO] MODE: Is the same as Normal mode, except it forces the oscilloscope to trigger if the trigger conditions are not met.
[NORMAL] MODE: Displays a waveform when the trigger conditions are met, otherwise the oscilloscope does not trigger and the display remains unchanged. Normal and single modes are useful for capturing sparse or single waveform.
[SINGLE] MODE: Is the same as normal mode except that oscilloscope will enter HOLD state after a trigger has been detected and waveform display has been updated.
TURN ON/OFF MEASUREMENT DETAIL: Press [OK] button for about 2 seconds.
WAVEFORM SAVE/RECALL:
a) Press [SEL] & [+] simultaneously: Save displayed waveform to non-volatile memory.
b) Press [SEL] & [-] simultaneously: Recall saved waveform.
0V LINE ALIGNMENT
If the 0V line (the trace corresponding to 0V input voltage) does not match the VPOS indicator at the screen left border, it can be fixed by performing the “0V line alignment” function. 1. Set the [CPL] switch to GND position. Then press [SEL] button until VPOS indicator is highlighted and hold down [OK] button for about 2 seconds. The trace with be aligned to VPOS indicator when you release the [OK] button. It is normal for some residue mismatch to remain at the highest sensitivity settings.
PROBE CALIBRATION
Problems may need calibrating for more accurate results at high frequencies.
1. Connect the clip to the test signal terminal and leave the black clip (ground) disconnected.
2. Set [SEN1] switch to 0.1V and [SEN2] switch to X5. Set [CPL] switch to AC or DC.
3. Adjust time base to 0.2ms. You should see a square waveform. If traces are not stable adjust
trigger level (the pink triangle on right screen border) until it is stable.
4. Turn C4 (capacitor trimmer) with a small screw driver so that the waveform displays sharp right angle.
5. Set [SEN1] switch to 1V and [SEN2] switch to X1. Keep all other settings unchanged. Adjust C6 until a sharp right angle waveform is displayed.
TEST MODE: Is used to find possible opens (for all port pins) and shorts (for pins PB0 - 15, PC13-15). It first checks PB and PC pins with special patterns to find possible shorts. LED will blink fast if found. Otherwise, it will generate 3.3V and 0V alternatively at each port pins (PA, PB, PC, PD) at about 4 seconds. These signals can be used to check for opens.
How to use: Hold down SW4 and press RESET to enter Test Mode.
If LED is blinking fast that means there are shorts on PB or PC pins.
Find out the shorts before continuing.
If LED is blinking slowly, use a volt-meter to check each pin related connections that are suspected open. If there is no voltage change at a point which should be connected to a port ppin there may be open between the point and port pin.

[@tsbrownie]

I have added what I have found on the internet in the description. I don't know how reliable the different sources are, so use at your own risk. Some things found since the video: The two "Sen" switches are multiplied to give the volt setting in the lower left corner. Video of the walk around of this o-scope: kzbin.info/www/bejne/f2bNp62KhMp7gcU $23 Fnirsi-138 Pro Vs. $25 DSO138 Oscilloscopes kzbin.info/www/bejne/j3_HZGZ4epmKgsU USB oscilloscope: kzbin.info/www/bejne/jmqsf4WpmMmnhdE USB Pros & Cons: kzbin.info/www/bejne/nJS4l2SjZ82ee9U

[@macmccune21]

Tour was interesting and helpful as could possibly be! I am a novice / inexperienced with this sort of thing, bought a soldering iron a a few practice kits last month. Saw this old DOS138 on Aliexpress for like, 5 bucks and always wanted an Oscilloscope since 2011! This video confirmed my purchase was a sound one, assuming I dont fry it putting it together!

[@tsbrownie]

Good luck. I have some videos on soldering that might help.

[@vasyasmanager2you]

Hey, nice review. As for the manual, i found them easily. Google censors any direct links, so just give the directions. The footer of official Jyetech site is referencing their official reseller Accudiy. There you can find your model and on your model's page you'll find links to official Jyetech manuals (including calibration procedures) and full schematics etc. (More docs for DSO138mini models than for older DSO138.) Best Regards 👍🏼

[@tsbrownie]

Very interesting. Thank you for this!

[@SirSteveFury]

I got this to ding around with. I just couldn't resist at $12. My wave forms distort beginning around 30khz. Good for audio work I guess. My main scope is a Tektronix 2246 and old BKP 1477. Yes, This would have been wonderful in the 1970s when I started fixing stuff.

[@tsbrownie]

I will have to try it out against my "real" scope and see. Will be interesting.

[@uni-byte]

There are better choices these days, but this was a breakthrough back 3 or 4 years ago. BTW, your probe is not properly compensated. It can be done but it's an rather drawn out iterative process. Your happy, so no worries.

[@teddypreston5525]

Thanks for sharing. Do you happen to have the pdf file for this particular version (V1.5)? I have been looking all over the internet for the pdf version. Thanks in advance.

[@tsbrownie]

I have it, but legally I can't distribute other people's stuff. The file names I found are DSO138UserManual_138_new.pdf and DSO138UserManual_138mini_HJ.pdf. Note that many companies make this same product, so these manuals may not be for your exact model (they were not for mine), but they are close enough to get 95% of the functions.

[@teddypreston5525]

@@tsbrownie Thanks. I got a print-outs that came with the unit. I probably scan them (in high resolution) and will save them as a .pdf format. Not as good, but it will do the job. Thanks again.

[@ddelker]

Interesting video. I just got my DS0380 today and have been searching for a decent manual online. Most instructional info seems to be several years old, and software changes in the menuing system make it difficult to figure out the current functions. One thing you showed was the SEL action that changes parameters to be adjusted. Your scope goes from what I'd call the vertical position setting (pointer on the left) to the X1 / X10 "probe setting" that would be useful if using a 10X attenuator probe on the scope. Unfortunately, my version skips from the pointer on the left directly to the timebase setting. The X1 legend shows on the screen, but I can't see a way to change it. Anyone else have that issue? Another difference in my software version is that your display shows V1.5 at the upper left, while my screen is blank in that area. The only exception is that occasionally I've seen a red "0 Calib" legend in that field. (I can't remember what condition caused that). Finally, there seems to be a strange condition that occurs sometimes when I first connect the scope after powering it on: the "trace" seems to be completely above the top of the screen until I mess with the vertical position setting. Sometimes this happens; sometimes it doesn't. Anyway, those are the mysteries I'm still trying to figure out. Let me know if you discover anything related to these issues. Thanks again for an informative video!

[@tsbrownie]

Interesting, thanks. I wonder if there's 1 company making the hardware and a bunch of distributors putting their own software on it. It happens with big computer hardware.

[@ddelker]

@@tsbrownie I've read that the original oscilloscope design was pirated by several other companies who now sell knock-offs online, each with their own "features" and peculiarities. I'm not surprised that your DS0380 and mine have different user interfaces, even though they are essentially the same age!

[@michaelmounts1269]

There really hasn't been an update in construction or firmware since 2016...

[@sergei149]

Have spent 2 days looking for your comment. I have the same version as you and can confirm I cant change 1X and 10X probe settings as well as trigger indicator jumps way above screen after reset I think.

[@almotik8514]

Кто подскажет как подключить прямой вход на X и Y ?

[@tsbrownie]

Who can tell me how to connect direct input to X and Y?

[@JacobStevenson]

I have a "calibrate analog gain" function... have messed with this? know about what it does? because I ran it and I think I messed something up and I don't know how to revert it...

[@tsbrownie]

I don't have that. Have never messed with it. There's info in the description. Hope that helps.

[@johnstrawb3521]

The lack of a REAL manual is very bad news. Note for novices and near-novices: Whenever you're thinking of buying a device to use with or analyze electronics, find the manual online first and see if it makes sense to you. Equipment won't help you if you can't understand how and where and when to use it. --HOWEVER, JYE Tech does have a (too) short online manual. Search by [dso138 oscilloscope manual]. The current update is "Rev 05" for Revision 05. If you don't know oscilloscopes, see if you can make sense of this manual before buying.

[@tsbrownie]

I have put what I have found in the description. It is from many unknown sources, so I am not sure how good it is.

[@qwertykeyboard5901]

The screen with the frequency count, Vpp, and other stuff. How do you bring that up?

[@tsbrownie]

I had to go try it. It's the default. You push OK for about 2 seconds. I have a lot of that info in the description.

[@theAristocrap]

I am a complete amateur - could this be used to visualize wave forms for sound (specifically for a synth). Could a pass through probe be done easily (with basic soldering skills) to allow an audio signal to go through the oscilloscope?

[@tsbrownie]

Yes. As long as the input signal is within specs. Audio is easily within the range of this scope.

[@theAristocrap]

@@tsbrownie thanks! Will an off the shelf BNC to 3.5mm jack work?

[@tsbrownie]

@@theAristocrap It's hard to say without knowing what you are measuring. It likely will work. Make sure the output is not at dangerous voltage levels.

[@theAristocrap]

@@tsbrownie Basic headphone audio signal from a synthesizer.

[@Gavddotcodotuk]

is changing the PWM and duty cycle only altering the test signal that it outputs?

[@tsbrownie]

If I recall, yes. It has a built-in oscillator and frequency generator.

[@brunomoyano8727]

Hey i have the same one, is it me or the trigger is slow compared to others?

[@tsbrownie]

Can't say I've noticed. Will have to check.

[@kenzocanlas1135]

is it normal that the vrms also change if you change the voltage sensitivity ?

[@tsbrownie]

How much is it changing? 5% or 50%?

[@kenzocanlas1135]

i think its about 5 percent...as youre video shown..changing the voltage divsion the the vrms also change... same as my osciloscope

[@tsbrownie]

@@kenzocanlas1135 For the simplicity and cost of the scope, 5% is probably as good as you can expect.

[@kenzocanlas1135]

ok thankyou..but what i mean is check video 02:00 to 02:05... the vrms change value as you changing the switch for sentivity voltage... it that normal?. thats what i want to know :) hope you still answer me :)

[@tsbrownie]

@@kenzocanlas1135 This is from their manual (it's also in my description) "[SEN1] & [SEN2] switch: Adjusts sensitivity. The [SEN1] X [SEN2] = actual sensitivity. Displayed at panel lower-left corner." Does that help?

[@user-mj7mn1jy9h]

Здравствуйте есть у кого-нибудь прошивка на этот осциллограф на CH32F103C8T6

[@tsbrownie]

Hello, does anyone have the firmware for this oscilloscope on CH32F103C8T6

[@sohelahmed526]

How Can I Buy??

[@closertothetruth9209]

ebay, aliexpress

[@PSKResearch]

How bad could the case be? Show us the case.

[@tsbrownie]

The bottom of the case is visible. It's the top that's a problem. The top cover blocks the switches to the left, so only the tip sticks up and switching puts a lot of pressure on the (cheap) switch. It blocks the calibration output on top. And it makes the other switches either inaccessible or hard to use. I will include it next video.