New DMM/DSO, Fnirsi DST-210, 1ch 10MHz/48MSps (March 2025) - Page 1
Forum section: electronics / testgear

author: tunk
author_rank: Super Contributor
timestamp: March 07, 2025, 05:30:30 pm
content: Today's new Fnirsi:- 10MHz/48MSps (also model DST-201, 1MHz/5MSps)- 10mV/div ~ 10V/div- 50ns~20s/div (DST-201 500ns~20s)- DMM 20000 count- signal generator 0-50KHz (DST-201 0-10KHz), 0.1V-3.0V, 13 waveforms- 2.8" screen- size 177×87×35mm, weight 300g- price around US$60 (DST-201 $50)https://www.fnirsi.com/products/dst-210-dst-201Manuals:https://cdn.shopify.com/s/files/1/0694/8310/2426/files/DST-210_Manual_ZH_EN.pdfhttps://cdn.shopify.com/s/files/1/0694/8310/2426/files/DST-201_Manual_ZH_EN.pdf

author: the Chris
author_rank: Regular Contributor
timestamp: March 08, 2025, 06:38:19 am
content: They obviously have a typo on the main label. Should read "My time eater", I guess

author: BillyO
author_rank: Super Contributor
timestamp: March 08, 2025, 04:31:12 pm
content: What are the chances they have 19mm spacing on the jacks?

author: TurboTom
author_rank: Super Contributor
timestamp: May 24, 2025, 02:40:22 am
content: Chances for the "correct" spacing are nil -- the connectors are 17.5mm apart...Well, just for fun and to take the chance to have a really light-weight "universal" meter for the road, I gave this "Fnirsi" a go.It's quite peculiar what a mixed result and impression this instrument leaves. Actually, I'm really not sure how I should rate that thing. Considering the price of approx. 50€ that I paid for it, the expectations were low. Then again, once in a while there come really useful gadgets for little money from the "underdogs", just think of the "nanoVNAs". They don't claim (and nobody would expect it) to be professional gear, but useful anyways for some jobs. So that was my approach when I bought this item.So what have we got here? Basically, its a quite accurate multimeter in a rigid plastic box that's partially rubberized (appears to be silicone inserts and not that ugly soft-touch coating that always gets sticky after three years). The dial is not as "snappy" as on many other inexpensive far-eastern multimeters, it's rather a dampened an not as noisy cogging feeling, not unpleasant... Grouped around the dial switch are eight silicone rubber keys with a real membrane switch below. On the right side, there's another such key (power and menu function) and a small flap that hides the USB C charging / communication port and a hole to access the reset switch (didn't have to use the latter yet).The first test with my 10V reference showed the DC voltage range to be spot-on, just like many of the "cheapo" Chinese multimeters. They appear to take the initial calibration serious. After that test, a teardown was mandatory, so here's what I found:- build quality is really respectable, I didn't find any botches or reworked components on the accessible side of the PCB. I didn't remove the PCB from the casing since I didn't expect any substantial circuitry on the other side.- The DMM section is completely isolated from the Scope / Generator circuitry and the charge and USB section as well. I'm not too sure if the dielectric strength and the creepage distances are anything to rely upon (I rather err on the safe side so this instrument won't get used on any high-energy stuff).- Both amp ranges are fuesd, yet with soldered SMD fuses. I didn't expect HRC fuses but two small sockets wouldn't have blown the parts bill... Interestingly, the 10A range shunt is an SMD component (10mOhm) as well and is hidden beneath the light blue plastics cover for the input connectors.- The two "main" semiconductor devices have their markings laser engraved over, so identification isn't easily possible. Yet, I could identify the DMM chip to be an SDICmiro "SD7501".- The SOC section is arranged around a TQFP100 chip that I wasn't able to identify so far. The scope's analog front end utilizes a 3Peak 3PA1030 50MSa/s 10bit ADC of which the lower two bits apper to stay unused, hence the sampled signal appears to have pretty low noise. The analog range switching is accomplished by a relay, a 74HC4051 analog MUX and two H&Msemi HM8091 high-speed opamps. All this seems not too shabby and works reasonably well. Triggering appears to be arranged via a 3Peak TP1961 high speed comparator.- I couldn't find any DAC or R-2R ladder that could give a hint how the waveform generator is set up. There may be a DAC integrated in the SOC, but since I couldn't identify it, I cannot tell for sure. It seems the output driver is a HM8091 (or possibly a pair of them -- one may be installed on the other side of the PCB) once again. The software is stored inside a Winbond 25Q64JV 8MByte flash chip.Further tests and findings:-Bootup time is acceptable (the first reading appears approx. three seconds after pressing the Power switch).- The "low" measurement ranges are rather limited: Unlike with many other DMMs, there's no mV and µA range. So the least digit in the most sensitive range resolves 100µV resp. 1µA.- There is no relative measurement.- There doesn't seem to be a dedicated "Reset" function for the permanent Min / Max registers. Toggling "Live" Mode on and off resets the Memories.- The "Graphic" DMM mode permits storage and display of around ten readings which can be very useful.- Auto ranging appears to be reasonably fast, but then the displayed value still needs a moment (approx. three readings) to settle.- The "bargraph" display is useless since its update rate isn't any faster than the digital display and it even needs the same settling time, so there's no lower resolution but fast ADC used in the design.- the "Auto" mode is a nice gimmick that works fairly well for voltages > 800mV, DC voltages less than 600mV get interpreted as resistors. AC/DC selection works okay as well. But it wouldn't have been a big loss if the function wasn't there either...- AC voltage gets displayed at levels starting at 50mV. Below that, the display shows "0". But that can be considered normal for virtually all digital RMS converters. AC measurement is accurate up to 1kHz, and this includes the harmonics as well. Hence a 1kHz square signal reads well 20% low... Sine is pretty accurate, though.- The frequency measurement is nothing to write home about. It works up to approx. 25MHz but requires a level of 8Vpp to produce a reading at that frequency. Further sensitivities are: 4Vpp @ 20MHz; 1.3Vpp @ 10MHz; ~1Vpp @ < 1MHz- The type K thermocouple function appears to be spot-on vs. my process calibrator.- The oscilloscope function works as one may expect from an "el-cheapo" device like this. The trigger works fairly accurately and the sensitivity ranges from 10mV/div to 10V/div. One 100MHz x1 / x10 probe gets supplied in the kit, and the scaling factor can be entered in the instrument.- Since the sample memory is rather limited, one cannot expect miracles from this "toy". Nevertheless, when stopped, the horizontal adjustment range cover a ratio of 1:100 which means the waveform can be stretched by a factor of twenty and compressed by a factor of five. I'ld say, stretches above five result in duplication of samples, but on the small screen, the result still looks acceptable.- complex signals (i.e. an amplitude modulated carrier of a freq. ratio of 100:1) can be recognized as such, but stable triggering is virtually impossible and the carrier aliases badly on the screen. Higher ratios result in unstable, unidentifiable nonsense on the screen...- 3dB frequency is round about 15MHz (where triggering gets unstable); the specified 10MHz work well. The input filter appears to do a decent job, a square wave of 10MHz looks almost like a sine and aliasing products are basically absent.- the scope application permits multiple measurements that can be enabled / disabled individually- trace rate is abysmal, especially at slower time base settings- A frozen trace can be stored and downloaded to a computer via a function in the system menu as a "screenshot*.bmp". Resolution is 320x240.And now for the worst part of this gimmick...:- The wave generator can only output levels between 0V and 3V! This means, all signals have a positive offset. The offset cannot be adjusted. An amplitude adjustment always keeps the lowest part of the waveform at ground level, only the most positive parts are adjusted according to the amplitude setting. To generate a symmetrical signal, a DC blocking capacitor is required externally.- The signal is very granular. It seems this rather affects the temporal quantization than the amplitudinal. It seems a waveform consists of only round about 100 samples.- The output frequency is rather limited (50kHz at max). What's worse: If the signal frequency is set above 1kHz and the oscilloscope function is enabled while the generator is active, the signal frequency gets reset to 1kHz. This doesn't happen when the multimeter function is enabled. Yet, it's possible to output a waveform generator signal while one of the measurement functions of the "toy" is enabled. This makes me assume that the "big chip" isn't an FPGA but rather an SOC or powerful microcontroller of some sort. An FPGA wouldn't require to share computation power between the apps...My Take-away: I think, considering its price, this gadget may come in handy once in a while at situations where I normally wouldn't have a DMM, a scope or a (sort-of) waveform generator with me. Also, when travelling abroad, the small form factor and low weight are definitely a plus. The screen is fairly well readable, yet in direct sunlight you won't have a chance. If the chinese engineers only wouldn't always use a mix of Times and Courier fonts for the texts but some nice sans serif typeface instead, it would appear so much nicer and more professional. But I'm sure they will eventually learn. I'm equally sure that then, such gadgets won't get sold for 50€ anymore...I attached some photos and screenshots to accompany my monolog above.Cheers,Thomas

author: Aldo22
author_rank: Super Contributor
timestamp: May 24, 2025, 09:13:48 am
content: Thanks for the review!Although I probably won't be buying the device. Soldered fuses...Quote from: TurboTom on May 24, 2025, 02:40:22 amWhat do you mean by “normal”?For example, my Owon CM2100 also has no mV range, but can still display e.g. 3.2mVAC.

author: TurboTom
author_rank: Super Contributor
timestamp: May 24, 2025, 11:20:27 am
content: There are a few situations that producing a display at so low range readings may be useful, i.e. to figure out a tendency. But in my books, it doesn't make much sense to expect a half-way accurate reading below 10% of the range. This Fnirsi gadget starts outputting values at 2% of the maximum range reading (40mV in the 2V range, see photo -- i was a little "generous" with the 50mV figure in my last post) at an accuracy of approx. 2.5% of the measured value. This figure very quickly improves as the measured value exceeds 5% of the range.I'm used to this behaviour / configuration even on much higher quality bench multimeters, hence my take of this as "normal" - I should have been more clear here. Personally, I don't care if the instrument displays anything below such a low threshold. What can be argued is if it's a good idea to display "0" below such a threshold. An indication "Underrange" would make much more sense. But this may be nitpicking.For completeness, I added a few more photos / screenshots that would have exceeded the limit of my last contribution:By ripple frequency measurement, I was able to prove the temporal qantization of the waveform generator signal to be 100 samples per period -- his appears to be identical for all the included waveforms. Moreover, you will find a photo of the 10A shunt and of the LiPo charger circuitry.Cheers,Thomas

author: Aldo22
author_rank: Super Contributor
timestamp: May 24, 2025, 12:58:07 pm
content: @TurboTomOf course the limits are obvious.But the Owon still gives reasonably informative measurements, e.g. at approx. 20mVpp (100Hz square).The oscilloscope measures 9.34mVrms (AC coupling) and the Owon 0.0093Vrms.In any case, this tells you more than Fnirsi's “0”.

author: TurboTom
author_rank: Super Contributor
timestamp: May 25, 2025, 01:10:26 pm
content: Recent findings reveal that it's highly likely the "incognitized" CPU in this gadget is aWCH CH32V307VCT6 or rather a CH32V303VCT6-- at least the footprint matches and the performance would be adequate for the job. The ADC is connected to PB0~7, OSC, power and USB connectivity fits...

author: geonicz
author_rank: Contributor
timestamp: August 14, 2025, 03:56:45 pm
content: In addition to fnirsi's "accurate specs" there're hilarious overall experience. Mine is so perfect that this 'company' got a forever ban from me.As a person which had 4 devices from fnirsi, 3 of them dead or faulty right from their store or within a week(scope which showed 3.7v on 5 DC - 1013 maybe model; sag-55 hot air gun with random temperature right from the shop; dead power supply after plugging typeC cable in it dps150) , I'd avoid this company totally.