New (toy?) DSO, Fnirsi-138 Pro: 2.5MS/s, 2.4" screen - Page 1
Forum section: electronics / testgear

author: tunk
author_rank: Super Contributor
timestamp: March 02, 2022, 10:46:42 pm
content: New pocket DSO from Fnirsi:- 2.5MS/s, bandwidth 200kHz- 2.4" screen- with or without batteryA youtube review, saying the real bandwith is 50-100kHz:https://youtu.be/c7s6_YIaUJcFnirsi "official" store on aliexpress:https://www.aliexpress.com/item/1005003839624513.html?spm=a2g0o.store_pc_groupList.8148356.5.24c3718bE1TX09

author: Fungus
author_rank: Super Contributor
timestamp: March 03, 2022, 01:05:11 am
content: Looks like a repackaged one of these:https://www.aliexpress.com/item/1005003666640863.htmlThey're horrible. Not so much the 'scope (what do you want for $20?) but the user interface.

author: Brumby
author_rank: Unknown
timestamp: March 03, 2022, 01:38:48 am
content: I picked up a JYTech DSO138 as a kit (like the one Fungus linked to) so I could get in some SMD soldering and have something useful as a result. (There are clones and fakes out there and JYTech were keen for people to know how to tell the difference.)The UI is awkward, but it does work as a scope. It is limited in what it can do, so don't expect anything serious from it and you won't be disappointed.I did use it in anger once for a situation where I nothing else I had could do the job safely. I wanted to see the operation of a certain signal (around 5V amplitude) in a circuit that floated at a couple of hundred volts - so I powered it from a battery, attached it and set it up before applying power to the DUT. It performed perfectly for the task ... as a fully floating scope.One day I might spring for some differential probes.

author: tunk
author_rank: Super Contributor
timestamp: March 06, 2022, 11:28:05 pm
content: A very short review and a PCB photo here:https://www-ixbt-com.translate.goog/live/instruments/fnirsi-138.html?_x_tr_sl=ru&_x_tr_tl=en&_x_tr_hl=en&_x_tr_pto=scFrom the video and link above it uses a WCH CH32F103C8T6which is a 72MHz Cortex-M3 SoC with 64k flash and 20k RAM:http://special.wch.cn/en/mcu/According to this datasheet the ADC conversion time is 1us(run through google translate), so the 2.5MS/s claim may be inflated:http://www.wch.cn/downloads/CH32F103DS0_PDF.html

author: pcprogrammer
author_rank: Super Contributor
timestamp: March 07, 2022, 07:07:11 am
content: Quote from: tunk on March 06, 2022, 11:28:05 pmMost likely a clone of the STM32F103C8, and if so it has 2 ADC's. When used in interleaved mode they can get 2MSa/s. Still a bit lower then 2.5. But we know FNIRSI is not shy of lying about the capabilities of the equipment they sellBy the looks of it, and already stated by Fungus, it is very similar to the JYEtech scopes. I have a wave 2, the 2 channel version and don't like it due to the restless screen. When measuring it flickers quite a bit.

author: Oilngas
author_rank: Contributor
timestamp: March 08, 2022, 03:32:59 am
content: Quote from: pcprogrammer on March 07, 2022, 07:07:11 amI have a Wave2 and updating the firmware to 113-15801-080 from the JYETech site largely reduces the flickering issue. I see that the latest firmware is now 113-15801-092.

author: icezebra
author_rank: Contributor
timestamp: July 19, 2025, 05:08:25 am
content: I bought the version ofFNIRSI 138 Prowith no battery.I added a few components in the depopulated footprints to add the following (footprinted) functions:Li-ION Battery charge controller3.7V to 5V Boost ConverterMOSFET CHARGE/BOOST Cutover CircuitI noticed that the circuit designer put the isolation resistor before the chip power supply decoupling caps, so I added an electrolytic to smooth out the boost chip supply and went with a ferrite bead instead of a 0.3R isolation resistor. Also, instead of a separate RED and GREEN LED for CHARGING and CHARGED I placed a single RED/CREEN LED CHICLET because - coolness factorConstruction steps:1) Reflow the base of the power chip. It has a big metal plate on the bottom so a hot air chip tool or (crude) heat gun will be needed. Solder power chip pins and check for shorts to the power pad.2) Move the Tantalum from C49 to C30 and add the BOOST SUPPLY inductor.3) Add the Chiclet RED/GREEN LED4) Add the Caps, Diodes, Resistors, Electrolytic and depopulate the zero ohm resistor5) Add in a Li-ION Battery (Mine is 1500maH)See movies and photos attached here and post following for detail

author: icezebra
author_rank: Contributor
timestamp: July 19, 2025, 05:11:33 am
content: More photosI cannot load the movie showing the LED change from RED to GREEN upon charge complete, it is too large.

author: Peabody
author_rank: Super Contributor
timestamp: July 19, 2025, 09:31:38 pm
content: Going slightly off-topic, @pcprogrammer and @Oilngas, can I ask about your Wave2? I have one too, and I can't get it to work in Single mode. If I'm in Auto or Normal, and touch the probe to the test output on the top edge of the scope, I see the squarewave. But in Single mode I just get a single spike, then nothing. Do yours do that too? I've tried several recent firmware versions, including 092, but get the same result. If yours work ok, what setting do I have wrong that would cause this.Edit: Going back on-topic, the Zeeweii DSO154Pro costs more, but offers a lot more capability than this 138. I think the world has moved on since the DSO138 and DSO150, as useful as they were. But you can now get much more than 200KHz for not much more money, assuming you are buying from somewhere other than the US.

author: Oilngas
author_rank: Contributor
timestamp: July 22, 2025, 06:00:21 pm
content: Quote from: Peabody on July 19, 2025, 09:31:38 pmI see a single spike too, same as yours. I'm still on firmware version 113-15801-080.

author: Peabody
author_rank: Super Contributor
timestamp: July 22, 2025, 07:24:44 pm
content: Thanks very much. At least it's not just me. Well, I've notified a contact at JYETech about it, but I'm sure the Wave2 is nowhere near the top of their "important things" list these days. But if you see firmware later than 092, they may have fixed it.Actually, I think JYETech has been a solid supplier all these years. Their DSO138 kit kinda created a new class of product. And the DSO150 was even better for not much more money. I converted my 150 to battery power, and have gotten a lot of mileage from it. But the market has moved on since then. If I heard right, on that Zeeweii DSO154Pro, you can even zoom in.

author: icezebra
author_rank: Contributor
timestamp: July 23, 2025, 12:44:16 am
content: Quote from: Oilngas on July 22, 2025, 06:00:21 pmRegarding FNRSI 138 PRO trigger sensitivity in NORMAL mode: I noticed that the smaller the time scale, the less reliable and sensitive the trigger becomes on AC or DC coupling.Example: 50us wide pulse repeated every 158 to 170ms (i.e. at a frequency OTHER than a harmonic of the oscilloscope's time base with some frequency jitter.) On the 10us time scale setting the pulse rarely (if ever) appears on the screen and when it does it is typically less than 50us wide, indicating that the trigger fired more or less randomly.As time scale is widened to 20us then 50us the waveform appears more frequently, but the width is incorrect and variable and it is harder to measure the narrow pulse accurately, as the pulse gets more and more compressed on the time scale of course. AUTO mode is not much better.Regarding firmwarefor the FNIRSI 138 pro, I seem to have v25.5. Does anyone have this firmware download file or any other firmware download file for the FNIRSI 138 pro? I tried asking FNIRSI customer support however, they are radio silent.Also, I did an Internet search of reviews (nothing found pertaining to pulse trigger performance) and asked Google AI about the triggering for narrow pulses on this product. FWIW printout of response attached.Finally, this review I found in Russian language claims it is possible to use the USB interface to capture screen shots:https://www.ixbt.com/live/instruments/fnirsi-138.htmlI have not been able to reproduce this functionality

author: gre
author_rank: Newbie
timestamp: October 11, 2025, 03:39:21 pm
content: Bin ganz neu im Forum und Besitzer eines Fnirsi-138 Pro und bitte um Hilfe bzw. Hinweise, wie ich das empfohlene Firmware update bewerkstelligen kann.Rechner ist ein Windows 10 PC. Bisher bin ich nur soweit gekommen, dass sich im upgrade Mode befindet, unten auf dem Display FNIRSI blinkt, aber weiter nichts passiert.Über den libususb-win32 - Treiber sehe ich AIR01 mit USB\VID_0483&PID_002A (libwdi autogenerated), aber da fehlt wohl noch etwas, oder der Treiber ist nicht "zuständig".Im Voraus besten Dank.

author: BillyO
author_rank: Super Contributor
timestamp: October 11, 2025, 06:48:48 pm
content: Did you actually find firmware for it? Is there a problem you are trying to fix?With FNIRSR products, the usual way to update firmware is to plug the device into a PC, turn it on while holding some button (the "OK" button in this case), then a disc drive should appear on your PC. You then copy the firmware into that drive and the update will proceed automatically.However as far as I know, no firmware has been released by FNIRSI for this model. I have one of these and don't see anything that needs fixing. It fully meets it's specs, unlike what is mentioned in the first post of this thread, and all functionality works as described in the manual. Kind of unusual for a FNIRSI product, actually.

author: gre
author_rank: Newbie
timestamp: October 16, 2025, 04:24:04 pm
content: Danke für die Aufklärung. Zunächst zum Stand: Das Gerät funktioniert; da die Auswahl der Betriebsweise nicht mit dem Manual zu bewerkstelligen war (und diesem nicht entspricht), hatte ich gehofft, dies mit dem im Manual empfohlenem Firmware Update zu verbessern.Ich habe keine Firmware-Software und konnte keine Quelle entdecken. Und, wie beschrieben kann ich zwar das FNIRSI-138 in den update Modus versetzen, aber es passiert nichts, außer dass im Gerätetreiber die in meiner ersten Nachricht genannte Device auftaucht, mit der aber mit den vorhandenen Treibern nicht kommuniziert wird (die demzufolge im Windows-Explorer nicht erscheint.Wenn an dieser Situation nichts zu ändern ist, bitte ich erfolgreiche Nutzer des FNIRSI-138 dazulegen, wie man gezielt DC-Mode, und Triggermethode) einstellen kann (Bei mir sind Änderungen nur der Auto-Taste möglich und laufen dann automatisch verschiedene Varianten durch. Danke für Eure Geduld.