LCR Tweezer Fnirsi ST1 vs. Zoyi MD1

[DaneLaw]

Fnirsi's ST1 LCR tweezer and how it stacks up to Zoyi MD1 - pro & cons between them.
They do differ more than I expected, even though the test fundamentals are the same. (AC 0.3v 0.6v & 100, 1k, 10k Hz)
Will try to highlight some of the differences.

Values on these two units.
ZOYI MD1 =
0.6v AC (597.6mV)
0.3v AC (298.9mV)
100Hz = 100.4Hz
1K = 1004Hz
10k = 10.040Hz
[FW1.7]

Fnirsi ST1 =
0.6v AC = 604.9mV
0.3v AC = 302.7mV
100Hz = 100.8Hz
1K = 1008Hz
10k = 10.080Hz
[FW1.5]


* On the Fnirsi ST-1 you can toggle secondary parameters. [D, Q, Z or X] by pushing the jog-wheel, Im not familiar with that you can do that on the Zoyi MD1?..
* ST-1 datalog your values by hitting HOLD-button to an excel sheet on its internal memory.
* MD-1 does the same logging with HOLD (from fw1.7) but uses a txt-sheet.
* ST-1 indicates in the manual that you (at least to an extent) can zero/relative your value with a short push on the turn-on button.
* ST-1 has a significantly more pointy gold-plated tweezer tip than MD-1, same goes for the angled tips that come incl. with the bag-bundle, MD1 also comes with extra
   gold plated tips, but looks like the same variant as the fitted ones.
* The thicker tips on the MD1 are more firm, than the longer & sharp ones on ST-1.
* ST-1 is fitted with 1 metal finger-screw at each side, and one secondary guide hole/connection point.
* MD1 tweezer tip is fitted with two inserted screws at each side, and the resistance reading on Zoyi MD1 do seem more stable than my ST1-unit that tends to bounce,
   depending on pressure, & the connection points from tweezer tips to handle.
* ST-1 has a magnetic back, so you can attach things to it or hang it away on a metal surface.. it comes with an included metal disk with adhesive.
* ST-1 weighs 44g and MD-1 37g and a tad shorter-.
* MD-1 is significantly more stable in its reading than Fnirsi ST1.
* Would have preferred a 2-screw tipblade-fitting on Fnirsi ST1, as we see on MD1 and ST42 and most other LCR tweezers
* You can adjust the screen brightness, buzzer volume, screen orientation, time-delay for auto-off, and both units rely on the common TypeC charging interface for their
   internal LIPO cell, while FW-update, is the same run-of-the-mill .bin file to root-folder.
* Zoyi MD1 Modes: Auto, Res, Capacitor, Inductor, Diode, Continuity buzzer with a given Ω value.
* Fnirsi ST1 Modes: Auto Res, Capacitor, Inductor, Diode/Continuity buzzer.

Overall I like them, though also worth having in mind, I dont have any other LCR tweezers, so some of the fondness could be down to a honeymoon LCR tweezer phase.
The MSRP on the Chinese market seems to be 138CNY (19.5$) and doesn't look to be any significant price difference between them in China, while on the western optimized reseller sites. the Fnirsi ST1 seems to be a tad more expensive, both use a 4wire kelvin measurement AC approach.

[DaneLaw]

You can adjust the screens update rate on the Fnirsi ST1, as the update-rate seems to be sensitive to the selected frequency, so way faster update-rate at fx 10.000Hz (3 to 5 times per second) than fx 100Hz selected (around 1 time per second) while 1K/1000Hz is around 2 to 3 times per second.
This behavior ain't the case on Zoyi MD1, which stays around 1 update per second on all selected frequencies..

Video example with 100Hz, 1k, and 10K Hz and screen update rate that changes with frequency..+ toggling through secondary parameters. https://i.imgur.com/mXXOhh0.mp4

Zoyi MD1 [Atm latest firmware 1.7]
FW = https://zotektools.com/firmware-update-md1/
Manual = https://drive.google.com/file/d/1uJsOOQG1xBg4W1QcAgkmIN8IeYh9oZYz/view

Fnirsi ST1 [Atm latest firmware 1.5]
FW = https://www.fnirsi.com/cdn/shop/files/LCR-ST1-V1.5.zip
Manual English: https://static.eleshop.nl/mage/media/downloads/LCR-ST1-Manual.pdf
Manual CN/Eng. = https://www.fnirsi.com/cdn/shop/files/LCR-ST1-Manual.pdf

[skander36]

ST1 fw. is 1.5 and still can't test diodes. It show 0.65V in both both directions.

[DaneLaw]

I don't think I have tested either of them on diodes yet, It's kind of an uphill battle with 0.3v and 0.6v.

[tautech]

I don't think I have tested either of them on diodes yet, It's kind of an uphill battle with 0.3v and 0.6v.

Just how ?
Any half decent diode test will display Vf regardless of value.

[DaneLaw]

I don't think I have tested either of them on diodes yet, It's kind of an uphill battle with 0.3v and 0.6v.

Just how ?
Any half decent diode test will display Vf regardless of value.

As emphasized, haven't tested diodes with either of these, so what it does and doesn't do in regards to diodes - and if its a half-decent diode-tester after a given criteria - its all up in the air.

You could get one and find out - if these 19.5$ LCR tweezers are "half decent" diode-testers after your own criteria of half-decent....I somewhat doubt it... do recall an obs-notice in the manual about the use' when testing diodes. (*manuals posted above)
I usually turn to other items when testing diodes, but that's another matter... these LCR tweezers ain't targeted lighting LEDs or a wide aspect of diodes.. with the power they operate with, you're poking at the knee region of many diodes with the ltd current.
You also got a continuity buzzer., like most half-decent LCR SMD tweezers should have.. 

// Here buddy...https://www.keepontesting.com/post/zoyi-zt-md1-bonus-review   
I found an article that tested numerous diodes with the Zoyi MD1, so you can read that feedback, and see if it's your "half-decent" diode tester.

I haven't tested diodes with it, so can't help you, though, do have in mind, it's not the ST1 as Skander36 refers to, but the other MD1 model in this thread..
The article does highlight limited current when dealing with certain diodes... 

[Aldo22]

Just how ?
Any half decent diode test will display Vf regardless of value.

I think it's somewhat useful for determining polarity in-circuit "while you're at it" and if Vf isn't too high (Zoyi MD1).
For everything else I would use a transistor tester.
I wouldn't use the word “decent” for this feature.

[tautech]

Just how ?
Any half decent diode test will display Vf regardless of value.

I think it's somewhat useful for determining polarity in-circuit "while you're at it" and if Vf isn't too high (Zoyi MD1).
For everything else I would use a transistor tester.
I wouldn't use the word “decent” for this feature.

Yeah well, just what do you need other than polarity and Vf ?

[Aldo22]

Yeah well, just what do you need other than polarity and Vf ?

It's not really accurate and Zoyi is apparently not really proud of it either:

The product's diode forward voltage measurement value is for reference
comparison only, with a measurement range of Vf 0.1V~0.6V. Values beyond
this range will display "OL." For higher measurement requirements, select a
more professional diode measuring instrument.

But yes, in many cases it will show you the polarity.

[Frex]

Hello,

I own too the Finrsi LCR-ST1 and I don't understand the complain about the diode test.
I have latest firmware (1.5) and the diode test work well, it display voltage drop
and a picto on screen show the direction of the diode (no need to take care about polarity).
Right, displayed Vf value are (much) higher than expected, but for checking purpose I think it's sufficient.
And I like also, the continuity test mode  allowing easy short circuit find (R<50Ohms).
Very good value for money IMHO.
Regards.

Frex

[awakephd]

The Zoyi MD1 will display the diode direction (and voltage drop? I think? I didn't pay much attention to that, as I was only interested in polarity) for an ordinary silicon diode, but it cannot test an LED. Frankly, with only .6V, I am surprised it can get over the threshold for an ordinary diode!

[skander36]

The complain come from the fact that diode function is behave like is not working. The voltage is the same in both directions!
On Fw1.3  the minuscule diode icon on left is not changed at all. So with that behavior for someone used to check a diode with a DMM this function seem to not working.
I have installed 1.5 fw and indeed now the icon is rotating to show the sense of diode. But the voltage is still the same in both directions. Is the same AC signal (0.6V AC)  used to check the LCR components so maybe they should apply a separate voltage for diode.
Anyway for his price this device is pretty good because they manage to read LCR values with reasonable precision in most of the cases.

LE - In this video at 6:14 the diode test realized by one youtuber. -

[awakephd]

Since it gives you the polarity, it seems to make sense that it shows the same voltage either way - it is giving the voltage drop (perhaps not very accurately), and indicating the direction of that voltage drop with the icon on the left. Or at least, that is how I understood it - ?

[Aldo22]

How do you interpret that?
GM328A says 705mV, AN8008 says 621mV and ZT-MD1 says 520mV.
The diode was a 1N4148. The datasheet says Vf=1V, if I read that correctly.

Are they all off, or what does that mean?

[KungFuJosh]

How do you interpret that?
GM328A says 705mV, AN8008 says 621mV and ZT-MD1 says 520mV.
The diode was a 1N4148. The datasheet says Vf=1V, if I read that correctly.

Are they all off, or what does that mean?

"Forward voltage: IF = 10 mA, VF 1V (max)"

The datasheet says to expect 1V maximum Vf with If at 10mA.  You're under that, and I'm assuming it's unknown what the test current level is.

[Aldo22]

"Forward voltage: IF = 10 mA, VF 1V (max)"

The datasheet says to expect 1V maximum Vf with If at 10mA.  You're under that, and I'm assuming it's unknown what the test current level is.

That's right, thank you. I had forgotten about that.
So:
An8008: 1.4mA -> 620mV
GM328A: 4.2mA -> 714mV
ZT-MD1: 0.058mA -> 520mV

This is somewhat consistent with the data sheet.

[KungFuJosh]

That's right, thank you. I had forgotten about that.
So:
An8008: 1.4mA -> 620mV
GM328A: 4.2mA -> 714mV
ZT-MD1: 0.058mA -> 520mV

This is somewhat consistent with the data sheet.

The first two look okay based on Figure 4, but the MD1 looks high looking at Figure 3. 60µA looks like it should be 475mV...but whether that's off because the MD1 isn't great, or because of ambient temperature is another question. Was it -25C while testing? 😉

[Aldo22]

The first two look okay based on Figure 4, but the MD1 looks high looking at Figure 3. 60µA looks like it should be 475mV...but whether that's off because the MD1 isn't great, or because of ambient temperature is another question. Was it -25C while testing? 😉

I don't know that. It could be that the hand warms it up.
But maybe I measured it wrong.
The MD1 uses sine waves to measure diodes.
I'll have another look tomorrow.

EDIT: If I measure the AC current (TRMS), I get 0.14mA. That looks better

[Paul T]

I described the diode function (and other things) in my blog here:

ZOYI ZT-MD1 Bonus Review

[Aldo22]

I described the diode function (and other things) in my blog here:

Yes, I had already read it.
Very nice review!
And yes, I also didn't understand why Rs and Q are not logged.

[Paul T]

I suggested a firmware update contains Rs logging and beep on diode detection.

I'm thinking I need both. 

[DaneLaw]

Continuity buzzer.
MD1 got a dedicated buzzer mode, while ST1 beeps in Diode-mode.
MD1 do in fact also raise the screens update-rate with higher frequency-selected (at least in some modes)

*Click the speaker-symbol for sound, the Zoyi MD1 is maxed out on its buzzer level, to give an indication of max volume..
Zoyi MD1 - Quite a difference in reactiveness, between the Hz-modes.. Here with 10K vs 100Hz to elevate the difference in screen-response

Fnirsi ST1  (*Btw can you toggle the secondary parameters Q,D,Z,X on the MD1, like exampled here with ST1?)

[Phil1977]

I just have both tweezers of the thread title available for comparison.

Beside being a very similar product in general, the Fnirsi ST1 is significantly more responsive. Especially in Auto-mode the ST1 may take 0.5s to show a reading after making contact with the DUT. The MD1 takes maybe 1s. It´s really not a big difference, but big enough to make a difference for me.

PS: Just checked with a potentiometer and video camera: The ST1 has an update rate of ca. 2Hz, the MD1 ca. 1.2Hz. Both devices have been set to Auto, 1kHz, 0.6V. What´s impressive with both devices is that they both do not show any visible delay for range or measurement type switching. That´s so much better than most "smart" DMMs which usually take seconds to recognize if they are connected to a cap or resistor and then have to try different ranges.

[Phil1977]

I have both tweezers available up to next week. If someone has and idea for something interesting to compare then please tell me.

In the dedicated Zoyi thread was mentioned that the ST1 uses a more classical AFE with two instrumentation amplifiers before a switch while the MD1 puts the switch first to save on the BOM. Maybe this explains why the MD1 seems to be slower.

[TheDefpom]

I just recorded a review for the FNIRSI and found that I could not zero them, the manual states it can be done, but in my case is doesn't actually zero, but goes down to NEGATIVE mOhm's, from power up it does -38mOhm when shorted, if I put a 100mOhm resistor on it I get about 67mOhm... trying to zero gets WORSE, down to negative 66 or so, and then negative 102mOhm or so ! if I then put the 100mOhm on it, I get about 2mOhm !

Tried all different things, no good.

It's on V1.3, tried to install V1.5... firmware doesn't take, I get the disk on the computer, and have boot loader 0% on screen, but copying the firmware .bin over results in no change at all, nothing happens, again tried doing it different ways, no good, probably because I am on a Mac rather than a PC.

UPDATE tried on a PC and got firmware updated, didn't fix the zeroing issue though, that is no different.