Zoyi ZT-MD1 - new LCR Tweezers - Page 1
Forum section: electronics / testgear

author: slavoy
author_rank: Regular Contributor
timestamp: July 31, 2024, 09:28:46 am
content: I don't see any detailed specs yet. Just this short info, and the price $48https://thedmm.com/shop/zt-md1/

author: TheDefpom
author_rank: Frequent Contributor
timestamp: July 31, 2024, 09:32:29 am
content: They are supposed to be sending me one to review... so watch this space :-)

author: Phil1977
author_rank: Frequent Contributor
timestamp: July 31, 2024, 10:33:37 am
content: Wow, they feature adjustable accuracy. That's something I really miss even at high end test gear, to select between 0.5%, 2.5%, 10%, ... etc

author: Aldo22
author_rank: Super Contributor
timestamp: July 31, 2024, 10:56:42 am
content: Why do these devices only work from the μH range?70% of my SMD inductors are in the nH range.I can measure these with the NanoVNA, but it is a bit tedious.Or am I interpreting this wrongly?

author: Phil1977
author_rank: Frequent Contributor
timestamp: July 31, 2024, 11:22:28 am
content: Just because 10cm of straight wire already have 0.1μH of inductivity.To measure on this scale you need matched RF connections - so using a NanoVNA seems very legit, though not really comfortable.The other reason is that only inductors over a certain "strength" behave ideal enough to be characterized buy a single μH-number. I´m no RF expert, but from my SMPS and denoising experience I think you need more than just the inductivity to characterize e.g. a ferrite bead that´s switched into the gate control of a power mosfet. You need the RF response including the Q-factors / absorption coefficients. But that´s out of the scope of a simple LCR-meter and it can again be solved by measuring with the VNA.

author: watchmaker
author_rank: Unknown
timestamp: July 31, 2024, 03:19:01 pm
content: Here is a video "review":

author: iet
author_rank: Frequent Contributor
timestamp: August 01, 2024, 08:14:43 am
content: Watched the video. At 3 minutes, measuring a 1000 uF capacitor. Multimeter-785 uF, tweezers-551 uF. Too big a difference compared to the nominal value.

author: indman
author_rank: Super Contributor
timestamp: August 01, 2024, 09:12:35 am
content: iet, this 1000uF capacitor is faulty, this can be clearly seen by Rs=2.192 Ohm and D=0.7599.For a working capacitor of such capacity, these parameters should be an order of magnitude smaller. Check out my photo below.The ZT-703S multimeter showed a capacitance of 795 µF then 785 µF, which also shows that the capacitance is not in order. The fact that the multimeter showed a higher value is also understandable, since the principle of measuring capacitance in multimeters differs from the principle of measurement in bridge-type LCRs.

author: iet
author_rank: Frequent Contributor
timestamp: August 01, 2024, 11:18:26 am
content: It turns out that if you measure the capacity with a multimeter, the capacitor is slightly outside the 20% tolerance. If you measure with tweezers and without additional parameters, it is clear that the capacitor is faulty. Even taking into account the faulty capacitor and the different measurement principle, the difference of 234 uF is very large.

author: indman
author_rank: Super Contributor
timestamp: August 01, 2024, 01:45:05 pm
content: Quote from: iet on August 01, 2024, 11:18:26 amYou are mistaken, on faulty capacitors of this type, the capacitance measured with a multimeter and a LCR bridge-type meter can differ by more than 1.5-2 times. If a faulty capacitor has a leak, the multimeter may, in some cases, show a capacitance that exceeds more big 20% tolerancethe rated capacitance. This fact is well known to experienced radio amateurs.

author: tonyalbus
author_rank: Super Contributor
timestamp: August 14, 2024, 04:37:56 pm
content: Here my Hands-On video, it arrived this week.Just like with the first types of the Scopemeter from Zoyi, its seems for now only available at AliExpress SNAKOL store.that seems like their early release store. again no branding on the box, that on later models prob. willZT-MD1https://go.tonyalbus.com/ZT-MD1

author: indman
author_rank: Super Contributor
timestamp: August 14, 2024, 05:14:43 pm
content: tonyalbus,Thanks for the quite informative video!This product still leaves many mysteries and questions. It is difficult, of course, to demand any high characteristics for such a low cost. Your video showed that the tweezers are quite fast in measurements and the RLC recognizes the main denominations with confidence.But there are big doubts about the reliability of the secondary parameters Rs, D, Q. This difference is especially clearly visible in the test where you measure a capacitance of 4700 μF. The D parameter of the tweezers is shown as 1.5, but on your Rioshui 4090 it was determined to be 0.6? The difference is almost 3 times!!!Have you checked the reliability of the tweezers readings at frequencies other than 1 kHz? And also with a different test signal level of 0.3V?

author: tonyalbus
author_rank: Super Contributor
timestamp: August 14, 2024, 06:08:35 pm
content: @indman4700 uFMD1. 0.6V - 1KHz : 4100 uF / D:1.3627MD1 0.6V - 100Hz: 4140 uF / D 0.17634090C 1V - 1KHz : 3755 uF / D 0.61814090C 1V -100Hz : 3943 uF / D 0.0923On the 4090C changing the voltage did not matter, did not try on try on the MD1The MD1 seems consistant with his (wrong?) valueI must add, i did not calibrate and used the 4090C for a while..

author: indman
author_rank: Super Contributor
timestamp: August 14, 2024, 06:14:46 pm
content: tonyalbus, Thank you, but do you agree that such testimony raises questions? Could you measure a few more examples of high-capacity capacitors, for example 1500-3300 µF?

author: tonyalbus
author_rank: Super Contributor
timestamp: August 14, 2024, 06:26:12 pm
content: @indman,At this point, i am not that into D and Q values, so i am not sure what i it should read.Myself i will not be using the product to much as i have the 4090C ready on the desk, and will be moving on the the next device in my queueTheDevpom will be receiving one also, i understand, he usualy dives deeper into the details, especialy now reading your commentsso who knows maybe he will.

author: indman
author_rank: Super Contributor
timestamp: August 14, 2024, 06:31:31 pm
content: Do I understand correctly that ZOYI sent you these tweezer for review?

author: Phil1977
author_rank: Frequent Contributor
timestamp: August 14, 2024, 06:50:44 pm
content: Do you know the reference resistor these tweezers are using? Is it switchable at all?As far as I know most serious LCR meters switch the resistor that´s in line with the internal AC source and that´s also used as the current shunt. For low resistance, high capacitance or low inductance you want low reference resistance and vice versa.I could imagine these tweezers only use one value or a very limited set of values. Then it´s no surprise that large capacitors (and especially their ESR) can not precisely be measured.Anyhow, these things seem much more versatile than the DMM-like tweezers.

author: indman
author_rank: Super Contributor
timestamp: August 14, 2024, 06:55:24 pm
content: Quote from: Phil1977 on August 14, 2024, 06:50:44 pmThis is true, but if the secondary parameters Rs,D,Q cannot be trusted, then they become a useless addition and can mislead you, right?

author: Phil1977
author_rank: Frequent Contributor
timestamp: August 14, 2024, 07:58:14 pm
content: Quote from: indman on August 14, 2024, 06:55:24 pmHard to tell without trying this thing.With conventional LCR-meters I always like to see the phase angle because it easily tells you how ideal a component is. A resistor with nearly zero degree, an inductor with 90°, a cap with -90° means you don't need to worry about anything parasitic.This plausibility check alone would make the secondary display worth to watch. And if this plausibility check is not working, then I honestly would also not trust the main value.

author: indman
author_rank: Super Contributor
timestamp: August 14, 2024, 08:03:48 pm
content: Quote from: Phil1977 on August 14, 2024, 07:58:14 pmD,Q also provide very useful and valuable information about the quality of the component.

author: ZhuraYuk
author_rank: Regular Contributor
timestamp: August 14, 2024, 10:45:33 pm
content: Seems to have identical specs to FNIRSI LCR-ST1. Similar design, just UI is different. I wonder if they share same board.Would be great iftonyalbusdid the teardown, that would be truly exclusive content.

author: tonyalbus
author_rank: Super Contributor
timestamp: August 15, 2024, 07:04:48 am
content: Quote from: ZhuraYuk on August 14, 2024, 10:45:33 pmFNIRSI sending me a LCR-ST1 too, its on its way, so can teardown both

author: Feuerbard
author_rank: Contributor
timestamp: August 15, 2024, 04:59:17 pm
content: Quote from: ZhuraYuk on August 14, 2024, 10:45:33 pmboard not the same but soc similar .

author: indman
author_rank: Super Contributor
timestamp: August 15, 2024, 06:15:53 pm
content: Artery AT32F403ACGU7 - ARM Cortex-M4F. Freq. - 240MHz, FLASH-1024 Кb, SRAM - 96+128 KbThe price in China is approximately $2 per unit.

author: TimMc
author_rank: Newbie
timestamp: August 19, 2024, 01:32:17 am
content: Quote from: tonyalbus on August 15, 2024, 07:04:48 amThank you for your demonstration and review! You inadvertently convinced me to get a DMMCheck Plus Rev 8.Are they both using a 4-wire method for measuring resistance? Would this be necessary given the size of the tweezers?

author: tonyalbus
author_rank: Super Contributor
timestamp: August 19, 2024, 08:44:53 am
content: Hold-on buying the DMMcheckPlus yet..i am trying to get discount vouchers for my viewers.Will release a video sooni am not sure what you mean with the 4 wire, the DMMcheckPlus is verified with a 4 wire indeed, if the tweezers uses it i am not sure, i need to open it,and i prob will at some point.

author: tonyalbus
author_rank: Super Contributor
timestamp: August 20, 2024, 06:24:51 am
content: On the DMMcheckPlus, at Welectron you get a 5% discount with voucher:tonyalbus5https://www.welectron.com/DMMCheck-Plus-Rev-8-Multimeter-Calibration-Referencepaying with banktransfer another 2%enjoy!Have not heared back from US yet

author: TimMc
author_rank: Newbie
timestamp: August 20, 2024, 07:29:01 am
content: I mentioned your Zoyi ZT-MD1 video on my DMMCheck Plus order from the US website (this one?) and Russ said that they would check it out.

author: tonyalbus
author_rank: Super Contributor
timestamp: August 20, 2024, 09:27:57 am
content: Quote from: TimMc on August 20, 2024, 07:29:01 amCool, thanks for mentioning my video , yes i emailed Russ, but he is a busy guy, hope he will get back to me and we can do a nice discount for US too.

author: infino
author_rank: Contributor
timestamp: August 20, 2024, 08:24:57 pm
content: tonyalbus5 does not work, it says that this code is one-time use

author: tonyalbus
author_rank: Super Contributor
timestamp: August 21, 2024, 06:45:48 am
content: Quote from: infino on August 20, 2024, 08:24:57 pmMaybe a hickup, for me it works.

author: Paul T
author_rank: Regular Contributor
timestamp: August 26, 2024, 07:58:26 pm
content: I'm now in possession of one of these meters now. Paid US$20 including a spare set of straight leads.I tested two dozen each resistors, capacitors, and inductors that I have reserved for calibration duty.I went into each dedicated R, C, L, and D mode to evaluate accuracy. For resistors I stayed at default 1KHz frequency. For L&C I went with 1K in the middle of the range and changed to 100 Hz for large L or C, 10KHz for low values. Output was set to default 0.6VFirst off, diodes are limited by the 0.6V output. No zeners, no LED's. The auto-polarity trick is nice, but the voltage drop is not very accurate, probably because of low output current. I get 0.37V across a Schottky (usually 0.19) and 0.52V across a silicon (usually 0.60). It probably pulses, I don't get a constant voltage or current from it.Resistance: it's extremely accurate for carbon or metal film resistors, no calibration of this unit will be needed! However, I assume because it uses AC output, it gets confused on wire wounds. It reads down to the milliohm and is within ±1% for everything I threw at it (10 milliohms up until 500KΩ). From 1MΩ on up, I found it's ±5%, mostly on the (-) side of things.Capacitance: Accuracy starts at 100 pF, below it jumps around too much. ±2% was found up to nearly 1 μF. Beyond that, up through my largest 22mF, I found it's ±5%, again on the (-) side of things. I wonder if the reduced accuracy has something to do with lack of DC bias for electrolytics?Inductance: Precision to 0.1 μH, accuracy starts way at the bottom. I measured the spectrum from 0.5 μH to 12.5 mH, my largest. I found it's a solid ±5% for everything!I'm very happy with the performance if this inexpensive pair of LCR tweezers. Amazing value! It has it's limitations, including terminal spacing, which made some of my components difficult to attach.Auto detection works really good in the LCR realm. Really fast! Don’t let the 1 second refresh scare you away. This is an impressive device for sorting a bowl full of SMD components quickly. However, components in the 10's of pF or nH range will require a different LCR bridge, perhaps using 100 KHz frequency.(I did not compare secondary measurements such as ESR, Q, D, etc.)Adding a plot of the % error results:

author: TheDefpom
author_rank: Frequent Contributor
timestamp: August 27, 2024, 03:08:03 am
content: I just received one of these also, will be doing a review video on them some time in the next couple of weeks checking them against my standards and comparing to other decent meters.

author: Paul T
author_rank: Regular Contributor
timestamp: August 27, 2024, 03:45:58 am
content: I started to check how well the secondary readings (Rs, D) compare to my ET431 LCR bridge at the same frequency / voltage settings.For D, they align sometimes, and other times can be widely different (2-25X difference).The ZT-MD1's "Rs" correlates well to the ET431's "ESR" very well for the electrolytics I sampled so far (within 10%).I'm wondering if they have a problem calculating D properly in the unit? I don't have a third LCR bridge for arbitration. Hopefully someone else can investigate this (please).By the way, I tried using it plugged in to charge. It functioned, but the readings were not as good. I recommend using it on battery only and not around EMF.

author: Phil1977
author_rank: Frequent Contributor
timestamp: August 27, 2024, 04:50:45 pm
content: Quote from: ZhuraYuk on August 14, 2024, 10:45:33 pmI just received the ST1. It´s much faster in detecting the component than all other multimeters with auto-mode I know. It instantaneously shows the value without any visible switching between measurement type or range. I don't see it as a highly precise measurement instrument, but as a very handy device to identify especially SMT-components.Probably the usefulness of the Zoyi is more or less the same.

author: indman
author_rank: Super Contributor
timestamp: August 27, 2024, 05:33:30 pm
content: Quote from: Paul T on August 27, 2024, 03:45:58 amSeehttps://www.eevblog.com/forum/testgear/fnirsi-lcr-st1-(inexpensive-lcr-tweezers)/msg5614289/#msg5614289

author: Paul T
author_rank: Regular Contributor
timestamp: August 27, 2024, 05:56:48 pm
content: Sorry I missed these discussions. Seems like a firmware update is desperately needed. My unit has v1.5.

author: Paul T
author_rank: Regular Contributor
timestamp: August 27, 2024, 06:46:03 pm
content: It appears they are getting ready to release v1.6. They have posted a how-to-upgrade video on YouTube.https://youtu.be/9sHBnaKmNdk?si=agKCKwcMEqPPoHWEEDIT: They added a link to the file. The PDF user manual link works now too.

author: TimMc
author_rank: Newbie
timestamp: August 28, 2024, 03:42:25 am
content: Firmware updates are linked on the product page:https://zotektools.com/products/zoyi-zt-md1/1.06: optimized the measurement speed for high resistance values

author: Paul T
author_rank: Regular Contributor
timestamp: August 28, 2024, 10:40:57 am
content: FIRMWARE V1.6 REPORTEasy to follow their directions and get the device updated.Previously, I was not able to measure some resistors above 1MΩ. I had assumed these must be wire wound, causing the issue. The meter now does these correctly, within 3% error.Sometimes the value "Rs" shows the value and the display shows "OL". Had this happen once on 2MΩ resistor and repeatedly on 20MΩ. At least the correct value is accessible at the bottom of the screen.As for the "D" value, I ran the series of capacitors I have and still found differences. All my caps are "good", such that the impedance angle is near -90 degrees for everything below 1 uF. In fact, sometimes my ET431 reports over 90 degrees and a negative ESR. This is where the devices disagree. I think both meters are trying their best to respond to a "fringe" condition, and "D" values several magnitudes apart from each other is not really the situation. They are just picking up the reactance differently. Perhaps it's wrong to expect both devices to have similar measurements.When I moved to capacitors 470 nF and larger, the ET431 and ZT-MD1 now agree on D value and Rs much more closely. These are electrolytics and tantalums and I am measuring at 100 Hz for most of them. I think the biggest difference is that the ZT-MD1 doesn't use a bias voltage on polarized capacitors.So my conclusion is both devices will have a different interpretation of the reactance when almost purely capacitive, and therefore may have what appears to be large differences in D. I don't think any firmware update is going to make either device appreciably better. Just realize what the D value represents and how it is calculated. Do the experts agree? Please let me know.

author: indman
author_rank: Super Contributor
timestamp: August 28, 2024, 11:39:34 am
content: Quote from: Paul T on August 28, 2024, 10:40:57 amThis tweezers is made with the most simplified circuitry possible in order to reduce production cost. It is silly to demand from it for 20$ reliable measurements in a large range and with fulfillment of all conditions of calculation of secondary papameters. Undoubtedly, the results will be different from professional bridge meters. We need to realize that and accept it.

author: Paul T
author_rank: Regular Contributor
timestamp: August 28, 2024, 10:38:19 pm
content: More good news - For inductance, I ran the series of inductors and found the Rs and Q values corresponded very well against the full-sized LCR meter I also have.I agree we may be expecting a bit much of an inexpensive device. For the price and size, it's pretty amazing to me how good it is.

author: Paul T
author_rank: Regular Contributor
timestamp: August 30, 2024, 11:23:24 am
content: A day or two later they have rolled out v1.7 firmwareUpdate details:1. Added the functionality to save and export measurement data.2. Improved the accuracy of low resistance measurements.3. Corrected spelling errors in English words.4. File name Tweezer01(4)(1).binhttps://zotektools.com/firmware-update-md1/I tried it, and can report success with the upgrade and correct spelling of "Language" in the menu.IMPORTANT WHEN YOU UPGRADE - Say "yes" to the format disk request to activate the export feature.The following video shows how to do that, halfway in:https://youtu.be/iKU4xQvX0q0?si=xNGRprcZwuxkkdSf&t=64Afterwards, your unit works like a 256 KB USB drive. Do not activate the USB boot feature to access export data - instead just turn on the device to measure screen an plug it into a computer.Every time you press "HOLD" the data will be appended to the "record.txt" file. You can start a new file by renaming the original text file or moving it off the USB drive.

author: Aldo22
author_rank: Super Contributor
timestamp: August 30, 2024, 12:51:48 pm
content: Quote from: Paul T on August 30, 2024, 11:23:24 amInteresting!I almost ordered the FNIRSI LCR-ST1 because it advertises "Data Hold & Log".Now the Zoyi can do that too.Still waiting for it...

author: TheDefpom
author_rank: Frequent Contributor
timestamp: September 01, 2024, 11:33:55 am
content: My review is here:🔴 Good LCR Meter ? - Zoyi ZT-MD1 LCR Tweezer Review - No.1274

author: TimMc
author_rank: Newbie
timestamp: September 03, 2024, 04:57:52 am
content: Here's a bit of a demonstration:

author: Paul T
author_rank: Regular Contributor
timestamp: September 08, 2024, 12:34:43 pm
content: A new video review, and also a different link for a more in-depth discussion. Two reviews for the price of one!ZOYI ZT-MD1 Bonus Review at KeepOnTesting

author: Aldo22
author_rank: Super Contributor
timestamp: September 08, 2024, 01:02:44 pm
content: Quote from: Paul T on September 08, 2024, 12:34:43 pmThanks for the video inhorizontalmode. Looks much better on the monitor.The LCR Tweezer is very nice and the price is good.Here I had made a list using the new save and export feature.https://www.eevblog.com/forum/beginners/questions-about-reference-resistance-at-aliexpress/msg5628211/#msg5628211

author: Aldo22
author_rank: Super Contributor
timestamp: September 08, 2024, 05:14:11 pm
content: Just found out that although the ZT-MD1 is not officially suitable for the nH range, it can be somewhat useful.It's not very precise, but it can roughly distinguish e.g. a 150nH from a 680nH inductor.Better than being totally blind.

author: Paul T
author_rank: Regular Contributor
timestamp: September 08, 2024, 08:55:43 pm
content: I found the same thing. I categorize (bin) my SMDs by the decade into little organizers. If the read 0.2 or higher I can put them in the bin. If 0.1 or below, I save them for my other LCR meter which does nH.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: September 09, 2024, 10:45:14 pm
content: Had one for a tad over a week, and first impressions are positive, not least with the price in mind.'Test with an older resistor board from a few years back (0.1% 25PPM)Its the very cheap variant of "precision resistor board" from Aliexpress, that can be had for under 3€ (incl 25%EUVAT & shipping)

author: Aldo22
author_rank: Super Contributor
timestamp: September 17, 2024, 10:12:57 am
content: Quote from: Paul T on August 30, 2024, 11:23:24 amHave you ever tried this?When I delete it, it writes a new file with the same contents as before.It seems to keep the data in memory.Not really a problem, I'm just interested in what it does when the 256 KB are full.

author: Paul T
author_rank: Regular Contributor
timestamp: September 17, 2024, 10:55:10 am
content: When I renamed the file, I did so by changing the file extension to OLD.Did you leave the file extension the same? Perhaps if it's still TXT it will not start a new file.Not sure how the program would respond to a disk full. It's probably coded to do nothing - that seems to be the safest thing. I suppose you could add junk files and see what it does. On the small chance it would brick the unit - I'm not going to be the one to try this. I paid for mineQuote from: Aldo22 on September 17, 2024, 10:12:57 am

author: Aldo22
author_rank: Super Contributor
timestamp: September 17, 2024, 12:45:36 pm
content: I renamed it (-> record.old), then this file disappeared. The folder was empty.The next time it created a new record.txt, which was really empty!A drive check showed an error. After the fix, the record.old was there again. I deleted it and now everything seems to work.Strange nonetheless.

author: battlecoder
author_rank: Regular Contributor
timestamp: September 18, 2024, 11:44:00 pm
content: I got this device recently and I have to say I'm quite pleased. I already had a couple of LCR meters, but I was curious to see how this one would perform given its low price.The provided factory calibration was good enough, but I appreciate that you can calibrate individual ranges if you have good reference resistorsIt's also quite fast and stable. It honestly surpassed my expectations.

author: Aldo22
author_rank: Super Contributor
timestamp: September 21, 2024, 10:13:01 am
content: Just as a tip: The MD1 generates a really nice sine wave.So you can use it as a simple, very small signal generator if necessary (100Hz, 1kHz, 10kHz / 0.3 or 0.6 Vrms).In any case, the signal is much cleaner than that of my XR-2206 and DMMs usually generate square waves (if at all).Unfortunately, the frequency is not super accurate.

author: mawyatt
author_rank: Super Contributor
timestamp: September 21, 2024, 12:18:58 pm
content: From another post WRT can the tweezers DUT current be measured. Might be worthwhile to see how the different tweezers use/control the DUT test current.https://www.eevblog.com/forum/testgear/smart-smd-tester-ms8911/This can be measured relatively easy with a small DUT resistor, say 1 Ω. Attach a DSO across the DUT and observe the measurement waveform from the tweezer, or if a DSO isn't available use a DMM. Keep the frequency low for the DMM since they usually don't respond well at higher frequencies.Another option if one has a DSO with 50 Ω input impedance, is use the DSO 50 Ω input Z as the DUT and simply measure such with tweezers.Maybe some folks with these tweezers can perform this simple test and report th results, we would IF we had any tweezers, unfortunately we don't!!Best,

author: Aldo22
author_rank: Super Contributor
timestamp: September 21, 2024, 12:54:51 pm
content: Quote from: mawyatt on September 21, 2024, 12:18:58 pmIs that what you want to see?1Ω (1kHz / 0.6Vrms) measured with the probes (1x) results in 17mVpp or 5.89mVrms.

author: mawyatt
author_rank: Super Contributor
timestamp: September 21, 2024, 01:50:36 pm
content: Quote from: Aldo22 on September 21, 2024, 12:54:51 pmYes exactly, thanksHere you can see nicely the waveform and evaluate the current as ~8.5ma peak.So with a 1.0 mill Ω DUT one could expect ~8.5 microvolts peak across the DUT, this will be a difficult level to resolve accurately and repeatability for the tweezers due to the limited level of test current which questions the validity of such low Z measurements with these tweezers.Suspect the same for the other tweezers and why we prefer a Bench type LCR Meter for low Z measurements which can deliver much higher DUT test currents.Best,

author: indman
author_rank: Super Contributor
timestamp: September 21, 2024, 01:59:32 pm
content: Quote from: mawyatt on September 21, 2024, 01:50:36 pmAbsolutely right, with such a low signal(current) there can be no talk of any more or less reliable measurement(Z) of low milliohm resistances. Therefore, there is no need to show us fantastic photographs where 0.5 mOhm is measured with these tweezers.These results will change randomly with each new measurement and depend on the pressing force of the tips. Moreover, the 4-wire circuit turns into a 2-wire circuit on the measuring tips of the tweezers.

author: Aldo22
author_rank: Super Contributor
timestamp: September 21, 2024, 02:30:35 pm
content: May I remind you that I didn't even pay $20 for this little device (including replacement heads, bag and delivery) and that it is quite useful and convenient for many cases?No one questions that a more expensive device measures more accurately, especially in borderline cases.

author: mawyatt
author_rank: Super Contributor
timestamp: September 21, 2024, 02:31:37 pm
content: Quote from: indman on September 21, 2024, 01:59:32 pmWe've had difficulty even with Lab Grade LCR Meters like the Tonghui TH2830 and Hioki IM3536 which can deliver ~150ma peak making low Z measurements with the quality Tonghui TH26009B Tweezer Fixtures (also with Standard Type SMD Fixtures). This is because of the uncertainty in contact details as you mention.WRT the 4-wire to 2-wire transition at the tweezers tips, this is why we developed the Split-Kelvin Type measurement fixture for LCR meters for low Z SMD components.Here the Force and Sense (4-wire to 2-wire transition) connections are made by the SMD component end terminals, thus considerably reducing measurement uncertainty due contact variations. We can state this technique works very well indeedhttps://www.eevblog.com/forum/projects/different-type-lcr-smd-fixture/msg5061028/#msg5061028https://www.eevblog.com/forum/testgear/sensitive-lcr-meter-measurements/msg5582175/#msg5582175Best,

author: mawyatt
author_rank: Super Contributor
timestamp: September 21, 2024, 02:40:52 pm
content: Quote from: Aldo22 on September 21, 2024, 02:30:35 pmOf course that's the intended purpose in evaluating a particular component with limited accuracy, it's only when folks start to look to these tweezers for precision measurements that brings up the question of measurement validityWe might even get these for quick and easy SMD Component evaluations, but never for any type component comparisons and details measurementsEven with expensive bench type LCR meters as shown above, one needs to pay close attention and understand the test setup and details if one expects repeatable precision results with low Z componentsBTW where did you get your Tweezers for $20 from?Best,

author: indman
author_rank: Super Contributor
timestamp: September 21, 2024, 02:41:47 pm
content: Quote from: Aldo22 on September 21, 2024, 02:30:35 pmThese cheap tweezers will certainly find their buyers and supporters, primarily due to their low price and fast speed of work in determining the main values ​​of LCR components in a fairly wide range. Nobody argues with this. But comparing them in terms of capabilities with more serious competitors in the form factor of smart tweezers is also pointless.

author: indman
author_rank: Super Contributor
timestamp: September 21, 2024, 02:51:01 pm
content: Quote from: mawyatt on September 21, 2024, 02:31:37 pmYes, I saw your development, a very interesting solution!

author: Aldo22
author_rank: Super Contributor
timestamp: September 21, 2024, 03:15:01 pm
content: Quote from: mawyatt on September 21, 2024, 02:40:52 pmOn Aliexpress (Snakol Instrument Store) with a “Choice” offer.It's worth the price imo. Actually, the price is almost ridiculous.

author: u37
author_rank: Newbie
timestamp: September 21, 2024, 08:12:53 pm
content: Here I am looking at this surge of Chinese activity and I am amazed. For many years (many YEARS!) there was only the "Marcus tester" on the market and everyone was completely satisfied with it. It doesn't matter that the indicator can't show anything reliably, but how convenient it is - you can poke any part and immediately see something. It is quite clear that the "Marcus tester" can't show anything on reactive elements, because it is not (NOT!) capable of doing this at any "frequency" with a test signal. I do not use the term "measure" on purpose, because an "indicator" product is not capable of "measurements".Now to subj - it, like other clones (LCR-ST1, SK-BD1, QPLCR), is a normal bridge measuring device. Despite all the shortcomings of the implementation, they (the shortcomings) are not so critical as to recognize the product as inoperative. It uses one of the "classic" measurement methods and this mechanism is maintained. I repeat, unlike the indicators of who-knows-what "Markus tester".In terms of accuracy and reliability, and also what you should pay close attention to.The bridge immittance meter has two components - V and I. The greatest error occurs at the range boundaries, when the V or I component becomes so small that the intrinsic noise and external interference begin to prevail over the useful signal. That is, at very small and very large values ​​(resistance, inductance, capacitance). There is no point in evaluating anything at a strong level, everything will be linear and noiseless there. Yes, it looks great - 1.2335 kOhm - oh, how many numbers on the screen! But try to get 1.2335 uOhm, and even so that all the signs stand still. No way? )) ... And this "no way" will differentiate the real quality of different implementations, frankly speaking, of software intelligence. The hardware is the same type, only the software processing changes. And in general, I have suspicions that the same people write software here, for example, ZT-MD1 and LCR-ST1 have too much in common. However, the size of the firmware file varies greatly, one team does not do this. But, this is not interesting.Another thing is interesting, why has no one made "alternative firmware" yet? There is no need to disassemble anything here, although IDA and J-Link work wonders, this is not necessary in principle. The processor is defined, the electrical circuit is drawn with the left foot with your eyes closed, as far as this circuit is obvious. There is a connector for the debugger - erase chip and in Keil. The subj itself is a simple LCR constructor, already soldered. You just need to add water. Add it at your discretion, and you can easily fix the obvious shortcomings of the current software. There is no 100+ kHz in the subj, is this normal? The equipment supports it quite well. Yes, there will be an obvious deterioration on auto-balancing "I", which will reduce the expected benefit, but it will still be better. Or, say, do you know that the MOSFET capacitance should be measured at a frequency of 1 MHz? This is done in order to adequately measure the relatively small capacitance of the junctions with a small test signal voltage. And what does subj do? - 10 kHz, and this is the maximum. How 10 kHz relates to 1 MHz, you understand. At 100+ kHz it will also be "bad", but not so much. I tried to make LCR with a pilot signal of 1 MHz in the "mobile" version and you know, if 100-300 kHz turns out to be quite calm, then at 1+ MHz there are so many negative aspects that the cost of the device simply soars into space. And the matter is not even in the expensive IV amplifier, AD8099 is not that expensive, but in the overall device. The high-frequency signal begins to radiate in one place of the board and gets to another part of it. This requires very strict shielding and separation of the receiving and transmitting nodes far from each other. The board sizes grow and do not fit into the device case.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: September 21, 2024, 09:18:37 pm
content: Quote from: Aldo22 on September 21, 2024, 03:15:01 pmSame goes for EU..it aint a lot over those prices that before VAT are very close to regional CN prices (19.5$/138CNY), at least at sale' though with incl. 25%EUVAT (danish)Picked both up in August and MD1 was a tad over 23 and ST1 around 26$ both are the bigger bundle variant with spare tweezers & bag (Incl. delivery & also 25% EUVAT)and then you usually get around 5% back in further Paypal cashback when ordering from Aliexpress through a cashback site, (it takes around ½ year before the funds are booked) but then again I lose nothing by using it, and it certainly does add up' but worth having in mind, if you use "influencers" affiliate links, then they won't get any kickback, as it will be yourself and the end-user that gets that around 5% kickback, as it will trump a given affiliate link.

author: Paul T
author_rank: Regular Contributor
timestamp: September 21, 2024, 09:24:33 pm
content: That’s right. The influencers will tell you it costs you nothing to use their affiliate links. This is only true if you do not use cash back plugin or browser. Sometimes I like supporting their channel and appreciate their information, so I use their link. I purposely avoid doing so with the clickbait types.

author: mawyatt
author_rank: Super Contributor
timestamp: September 21, 2024, 11:14:03 pm
content: Just ordered a Zoyi for $25.84 including tax. Couldn't find the Sankol store so ordered from the Official Zoyi Store which seemed legit!!Anyway, should have some interesting measurements awaiting when it arrives. BTW agree with folks, seems this is an amazing bargain.Best,

author: Aldo22
author_rank: Super Contributor
timestamp: September 22, 2024, 07:19:07 am
content: Quote from: mawyatt on September 21, 2024, 11:14:03 pmFunny, they now sell a version with "SNAKOL" printed on it and call it “SK-BD1”.Everything else seems to be the same.https://www.aliexpress.us/item/3256807359089613.html

author: gamalot
author_rank: Super Contributor
timestamp: September 22, 2024, 10:08:33 am
content: Quote from: indman on August 15, 2024, 06:15:53 pmIt’s not that expensive, in fact you can easily buy it in China for less than $1.

author: Paul T
author_rank: Regular Contributor
timestamp: September 23, 2024, 01:54:05 am
content: On the 1st of every month AE has promotions, including coupons. I took advantage of such a sale: Mine cost USD$19.77 which that included shipping, tax and the set of extra tips.

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 24, 2024, 01:40:27 pm
content: Here are some higher resolution pictures of it´s inside:

author: DaneLaw
author_rank: Frequent Contributor
timestamp: September 24, 2024, 07:26:53 pm
content: Quote from: Phil1977 on September 24, 2024, 01:40:27 pmLooks surprisingly decent with the price in mind. (good sharp pictures)

author: u37
author_rank: Newbie
timestamp: September 24, 2024, 08:41:20 pm
content: Hm.If you look at the photo a little more closely, you'll see something interesting. If the FNIRSI LCR-ST1 uses a classic design (two channels, two instrumental amplifiers, a switch, PGA), then for some reason everything is broken in Zoyi. First, a switch, then ONE instrumental amplifier, PGA. I wouldn't switch "inputs" even in my worst nightmare, then you'll end up with a lot of crosstalk, but Zoyi isn't afraid of that.I wonder why they did that?

author: Phil1977
author_rank: Frequent Contributor
timestamp: September 25, 2024, 06:28:37 am
content: Quote from: u37 on September 24, 2024, 08:41:20 pmThat probably also explains why the Fnirsi is double as fast as the Zoyi.I can't see any significant differences in accuracy though. I´ve done rudimentary comparisons to a tabletop DMM and to a handheld LCR meter and both tweezers match the results of the bigger instruments within 0.25% - that´s most impressive! Though I must admit I´ve tested quite "central" values only (10Ohm-100kOhm, 100pF-10uF).

author: mawyatt
author_rank: Super Contributor
timestamp: October 09, 2024, 05:45:03 pm
content: Just received the MD1, 1st impressions are quite good considering the price, actually even at twice the priceOne of those "Hidden Electronic Gems" everyone is looking for, like the SDS800X HD and KWR102 & 3.Best

author: Aldo22
author_rank: Super Contributor
timestamp: October 15, 2024, 11:34:51 am
content: Today I tried to measure an SMD inductor declared as 22μH.The measurement with the default settings of the MD1 seemed to be pretty far off. I played with the frequencies, but no change.Then I wanted to see if the DUT might be way off.I don't really have a better LCR meter, but I do have a GM328A and a NanoVNA-H.The GM328A has low precision, but what it reads seems accurate so far..02mH = 20μH / 800mΩThen I tried it with the NanoVNA-H. This is more precise: 23.5μH / 764mΩ.Rather by chance, I then lowered the voltage on the MD1 to 0.3V and suddenly the measurement was much better: 25.3μH / 782mΩ.Why is that? Is it a bug, or can it be explained?P.S. I don't expect miracles, a few percent difference is OK.Thank you.

author: indman
author_rank: Super Contributor
timestamp: October 15, 2024, 11:52:16 am
content: Quote from: Aldo22 on October 15, 2024, 11:34:51 amThe GM328A can measure such inductances much more accurately. If interested, private message me or check out the global thread on $20 tester clones.

author: Paul T
author_rank: Regular Contributor
timestamp: October 15, 2024, 11:59:05 am
content: @Aldo22Was the SMD inductor mounted on a PCB? Typically the lower voltage is appropriate for in-circuit testing.

author: Aldo22
author_rank: Super Contributor
timestamp: October 15, 2024, 12:13:45 pm
content: Quote from: Paul T on October 15, 2024, 11:59:05 amNo, it was separate, fresh from the packaging.

author: Aldo22
author_rank: Super Contributor
timestamp: October 15, 2024, 12:14:19 pm
content: Quote from: indman on October 15, 2024, 11:52:16 amThanks, I'll check that later. But the NanoVNA-H is actually the best I have, even for the nH range.

author: mawyatt
author_rank: Super Contributor
timestamp: October 15, 2024, 04:48:15 pm
content: Quote from: Aldo22 on October 15, 2024, 11:34:51 amWe just checked all the inductors we have as test DUTs, they range from under 0.1uH to 2.5mH and all readings seemed reasonable. We don't have a specific 22uH, closest is 10uH and 100uH, and they seem OK.We'll be happy to measure one with our various LCR Meters & Tweezer if you send, but likely someone in your area can help better.That does seem like a significant error in Ls and Rs, and makes one wonder if it's unique, or for all MD-1 units??Best,

author: Paul T
author_rank: Regular Contributor
timestamp: October 15, 2024, 05:12:35 pm
content: Quote from: Aldo22 on October 15, 2024, 12:13:45 pmI assume this is a small black rectangle type? I have found the same thing using 22 uH in this package. However, if I do the same test to a 22 uH exposed-wire spool copper winding, the voltage doesn't have as much of an effect.I found the following web site while looking for "voltage dependent inductance". It shows how these are actually wired inside. Sort of like a MLCC but with connections between layers to make a spiral instead of adjacent plates. It also cautions to avoid operating in the self-resonant range. So I would suppose there is a combination of inductance AND capacitance in this type of construction. And I have heard that ceramics can have a strong voltage dependence. Perhaps the lower voltage reduces such effects.https://www.doeeet.com/content/eee-components/passives/smd-inductors/Looking at my parts inventory, I don't have many little black chip style inductors over 10uH. Most of what I have are the spool type. Therefore, I would assume 22 uH is on the high end of the available range? Perhaps the unwanted voltage effect is a reason this high of an inductance isn't as common in small SMD packages.

author: indman
author_rank: Super Contributor
timestamp: October 15, 2024, 05:19:47 pm
content: Quote from: Aldo22 on October 15, 2024, 12:13:45 pmCan you show us a close-up photo of this coil?

author: Aldo22
author_rank: Super Contributor
timestamp: October 15, 2024, 05:46:08 pm
content: Thanks for all the answers!Here is just a quick picture of the SMD, more later.Quote from: Paul T on October 15, 2024, 05:12:35 pmYes, it is the highest value of these.

author: Aldo22
author_rank: Super Contributor
timestamp: October 15, 2024, 06:12:25 pm
content: Here the same with 10μH.The effect is smaller, but the lower voltage still matches the NanoVNA better (9.29μH)Btw. NanoVNA uses 160mVrms.

author: Paul T
author_rank: Regular Contributor
timestamp: October 15, 2024, 07:48:08 pm
content: OK then, 10 uH. Here's what I found comparing two different inductor constructions using a handheld LCR meter.BTW, nice homemade screen protector!

author: indman
author_rank: Super Contributor
timestamp: October 15, 2024, 07:54:01 pm
content: Quote from: Paul T on October 15, 2024, 07:48:08 pmIn this case, the closest value to the nominal value for the ceramic inductance would be at a test voltage of 0.5-0.7V.

author: Aldo22
author_rank: Super Contributor
timestamp: October 15, 2024, 08:17:31 pm
content: Quote from: Paul T on October 15, 2024, 07:48:08 pmThank you, that explains the observation.There are a few variables (frequency, measurement voltage etc) and it's not always easy to keep track of everything, especially if you don't know what the correct value should be.In this case, of course, the deviation was obvious because I knew what the approximate value should be.With the tweezers, it's also not always easy to keep the pressure constant to get a clear measurement, which is why I sometimes wonder whether more accurate tweezers are really that much more useful.Quote from: Paul T on October 15, 2024, 07:48:08 pm

author: Paul T
author_rank: Regular Contributor
timestamp: October 15, 2024, 08:22:24 pm
content: I learned something today.It seems little SMD devices continue to have their limitations and may behave differently than anticipated.Not everything can be shrinked without compromise.

author: indman
author_rank: Super Contributor
timestamp: October 15, 2024, 08:30:30 pm
content: Quote from: Paul T on October 15, 2024, 08:22:24 pmIt's true, you'll also learn and learn a lot if you can correctly determine with tweezers the true capacitance of MLCC ceramic capacitors. Their capacitance is also highly dependent on the applied voltage.

author: Paul T
author_rank: Regular Contributor
timestamp: October 15, 2024, 08:34:32 pm
content: I made the mistake of using MLCC capacitors with DC bias once. Couldn’t figure out why my circuit didn’t work right. Replacing with a tantalum fixed the issue!

author: mawyatt
author_rank: Super Contributor
timestamp: October 16, 2024, 02:04:53 pm
content: Quote from: Aldo22 on October 15, 2024, 08:17:31 pmExactlyTweezers are intended for "Casual" not Precision Measurements!We get a kick out of seeing discussions about making milli Ω Resistor and nano-henry Inductor measurements with these Tweezer types.One should note the lack of available test current from the Tweezer. Also the 4 wire Kelvin Connection is made at the back end of each blade finger on the PCB side after the blade attachment bolt(s). This means the blade finger, the attachment bolt(s) and the DUT to blade tip contact on each DUT connection (there are 2) is totally "Outside" any Kelvin compensation.The attempt to compensate for this low Z measurement uncertainty is the Zero Ω or Short Calibration which is subject to the same conditions as the DUT and thus subject to Zero Ω uncertainty. One should try and get repeatable measurements when shorting the tweezers tips together from time to time, we can't get anything within a few milli Ω and the result jumps around and as expected is highly dependent on the finger pressure!! This condition is also present with the expensive Tonghui TH26009B Tweezers for Lab Bench LCR Meters.With measurements like small pF range SMD DUT caps, the Kelvin Connection and DUT contact impedance issues aren't much of a problem since this is high Z measurements, however the placement of the users fingers on the tweezer handle influences the measurement and introduces uncertainty due to the unshielded 4 wire Kelvin active signal lines traveling down the handle (thin doubled sided PCB within the handle). The mentioned TH26009B Lab LCR Meter tweezers address this and have shielded lines within the handles up to the blade connection, but still fall well short of what a proper SMD LCR Meter Fixture can produce with a quality Bench LCR Meter where one can produce repeatable results in the fF region with small pF SMD capacitors.We've posted numerous threads on various fixtures for these different type Low Z and High Z measurements including a DIY technique we call "Split-Kelvin" where the SMD DUT terminals make the Kelvin connection thus removing the DUT contact issue which gives repeatable low milli Ω measurements in the micro Ω region, and verified by others.Anyway, these comments are not intended to bash tweezers, as every serious Pro and hobbiest should have a pair as they are highly convenient to make quick casual measurements just like a handheld DMM, however it's also good to see others question these tweezers wrt precison measurements at the Z extremesBest

author: Aldo22
author_rank: Super Contributor
timestamp: October 16, 2024, 03:00:22 pm
content: @mawyattThank you for your answer.As not even a hobbyist, I have made myself a very, very ugly clamp so that I can measure things with my NanoVNA-H for which I have no other instruments.The example in the attachment is a 27nH SMD inductor.The NanoVNA shows a stable 26.5nH, because I don't have to apply any pressure.What more could you want for $50?

author: mawyatt
author_rank: Super Contributor
timestamp: October 16, 2024, 03:23:50 pm
content: That works!!Maybe this technique could be applied to the NanoVNA?https://www.eevblog.com/forum/projects/different-type-lcr-smd-fixture/Best,

author: Aldo22
author_rank: Super Contributor
timestamp: October 16, 2024, 03:38:33 pm
content: Quote from: mawyatt on October 16, 2024, 03:23:50 pmThat looks very nice, of course.I'm just afraid it's a bit beyond my capabilities.

author: mawyatt
author_rank: Super Contributor
timestamp: October 16, 2024, 06:21:50 pm
content: Quote from: Aldo22 on October 16, 2024, 03:38:33 pmIt's not that difficult nor expensive, just a repurposed cheap Kelvin-Clip box from AliX (~$38), a Lever Arm Plunger also from AliX ($2~3) a custom PCB (~$4) (which we provided the Gerber for) and a couple 3D printed items (also provided files for), all toll less than $50One could replace the Kelvin-Clip box with a custom 3D printed box with 4 BNC connectors which should work fine, altho shielding with Al box won't be quite as good with 3D printed box.Also, this earlier version works well.Honestly this is so easy to do and inexpensive, which produces such an improvement in low Z measurements, it's a shame others haven't taken advantage of this Split-Kelvin technique.Besides this gives you a good excuse for getting a nice Bench LCR MeterBest,

author: notrhj
author_rank: Newbie
timestamp: October 20, 2024, 01:05:26 am
content: Does a real nice job testing small speakers. Tone, R and L

author: Aldo22
author_rank: Super Contributor
timestamp: October 25, 2024, 12:37:42 pm
content: Has anyone tried firmware 1.8 yet?Any idea what has been changed?https://drive.google.com/file/d/1eH6QX8KMslyW1YgegCdnmXhHu3Q_rLMa/view?usp=sharinghttps://zotektools.com/products/zoyi-zt-md1/

author: Paul T
author_rank: Regular Contributor
timestamp: October 25, 2024, 12:52:25 pm
content: I found out about it yesterday. I installed it and did not notice any changes yet. The log the device creates continues to omit series resistance Rs.I will post an update after retesting my sample components.I did need to manually reformat the internal storage FAT. Not sure if it was my computer’s fault when moving from v1.7 to v1.8. The data file was unreadable/corrupt until I did this.

author: Aldo22
author_rank: Super Contributor
timestamp: October 25, 2024, 01:36:52 pm
content: I have now also done the update.I can't see any obvious changes.However, the record.txt file works as before.

author: Paul T
author_rank: Regular Contributor
timestamp: October 25, 2024, 11:17:23 pm
content: I rechecked all my reference RLC components with the new firmware and as-supplied calibration in place. See attached image.I had to expand my chart out to 10% to capture some of the extreme values, was previously 5% for the same components.Resistance accuracy has improved, but electrolytic capacitors have more error for sure.My wishes for V1.9► Rs in the data log!► Beep on first connect of a diode► Automatic hold with a stable reading - that can be switched on or off. Beep when acquired.► Improve capacitance accuracy above 10 uF.

author: Aldo22
author_rank: Super Contributor
timestamp: October 26, 2024, 02:55:37 pm
content: Quote from: Paul T on October 25, 2024, 11:17:23 pmAre you sure that was better before?All I know is that these little testers are pretty off the mark with, say, a 470µF electrolytic capacitor.ZT-MD1 and GM328A show 430µFTC1 shows 440µFDMM: ZT-224 and AN870 show 445µFDSO-TC2 shows 463µF (1-3), which is closest to the specification.My measurement with the oscilloscope and the SG shows that the capacitor has pretty much the value it specifies (I hope I did everything right -> attached screenshot).

author: Paul T
author_rank: Regular Contributor
timestamp: October 26, 2024, 03:13:54 pm
content: My previous test results are here:https://www.eevblog.com/forum/testgear/zoyi-zt-md1-new-lcr-tweezers/msg5619277/#msg5619277I suspect environmental conditions may be slightly different. My reference values are based on average results from trusted devices, not from the labeled value. The error I found to the label is actually worse.I have noticed electrolytic measurements are not highly repeatable and can be influenced by tests done to other meters in between or by sitting without use. Even so, the trend is for this meter to under-report them.

author: Aldo22
author_rank: Super Contributor
timestamp: October 26, 2024, 03:39:20 pm
content: Quote from: Paul T on October 26, 2024, 03:13:54 pmYour new measurements agree with mine.But your old measurements...At 470µF it would have been less than 3% deviation (attached picture). So 456µF for example.I think mine was always further off.Can I put the old FW 1.7 back on it?

author: Paul T
author_rank: Regular Contributor
timestamp: October 26, 2024, 04:34:45 pm
content: It seems that testers like this are not the best thing to be using on electrolytic capacitors.“The effective capacitance of an electrolytic capacitor can fluctuate significantly under AC conditions without a DC bias”Perhaps that explains why each subsequent test is different and slow to stabilize.It would be awesome if they could provide some DC bias. That’s my firmware wish.I think I will avoid using this device on polarized caps unless that happens. It may be damaging the capability of the capacitor to store charge. Same with my HRM-10 internal resistance tester, which is also pure AC.“The alternating polarity of AC voltage continuously stresses the capacitor's dielectric layer, which can lead to breakdown or thinning over time, causing increased leakage current and potential failure.”

author: Aldo22
author_rank: Super Contributor
timestamp: October 26, 2024, 05:14:51 pm
content: Quote from: Paul T on October 26, 2024, 04:34:45 pmThey all do something different.I have just looked at 3 of them with the oscilloscope.The ZT-225 (DMM) remains in the positive voltage range.GM328A and DSO-TC2 also test the negative range.

author: Paul T
author_rank: Regular Contributor
timestamp: October 26, 2024, 05:24:01 pm
content: The handheld LCR ET431 I use has a polarized capacitor mode. Engages the DC bias voltage to maintain a positive voltage at all time.I suspect little transistor testers also use an AC signal since they do not have polarized inputs.

author: Paul T
author_rank: Regular Contributor
timestamp: October 29, 2024, 11:51:54 am
content: I reformed all my electrolytics, let them sit for a day, then measured them all with polarized, DC biased testers.Then I went about testing them with the ZOYI ZD-MD1 v1.8, followed by other testers without DC bias.With new averaging baseline, here is the capacitance error chart for the ZOYI. Improved, but still a trend continues to be low on larger capacitors.BTW all capacitors were remeasured and average adjusted, not just the polarized ones.

author: Paul T
author_rank: Regular Contributor
timestamp: October 29, 2024, 09:23:47 pm
content: I should have shared more information. Looking at my testers that did well at measuring capacitors, none of them did everything well. See attached image.In general, when measuring capacitance, the typical multimeter with a capacitance function did best above 0.1 uF. But you'd have to get out the LCR meter to get ESR.The LCR meters were most accurate below 0.1 uF, down to ten of pF, not really needing 100 kHz to give an accurate result.Although it takes quite a bit of time to measure 25 capacitors on 34 devices, including settling time, it's very satisfying to be able to look at the results and know which meter works best when I need an accurate measurement.

author: Aldo22
author_rank: Super Contributor
timestamp: October 30, 2024, 10:39:34 am
content: Quote from: Paul T on October 29, 2024, 09:23:47 pmYes, that seems similar to me.The ZT-MD1 is very good in the lower range (pF) up to approx. 10µF.I have more accurate measuring devices above that.I find the DSO-TC2 astonishing in the µF range, I had never compared it in this way before.Examples DSO-TC2 (compared with the declared value, not verified).100nF -> 97.84nF1µF -> 997nF10µF -> 10.2µF33µF -> 34.86µF220µF -> 228µF470µF -> 461.6µFThis seems quite reliable, compared to the other “cheapos” I have.

author: mir0tvorec
author_rank: Newbie
timestamp: October 30, 2024, 04:27:21 pm
content: Hello! I recently purchased such a meter. I found an error when measuring inductances. If you take and measure an inductor on a dumbbell, and then swap the contacts, the measured inductance will be different. For example, having measured an inductor of 100 μH, I got a value of 101.5 μH. Then I turn the inductor, swapping the contacts, I get 102..102.1 μH on the same inductor. Is it only my device that works this way or is it the same for everyone?

author: Paul T
author_rank: Regular Contributor
timestamp: October 30, 2024, 04:40:43 pm
content: Quote from: mir0tvorec on October 30, 2024, 04:27:21 pmWhat frequency did you use? This seems to be a repeatability issue. 10K may be more consistent at this low inductance.

author: mir0tvorec
author_rank: Newbie
timestamp: October 30, 2024, 06:55:03 pm
content: Yes, both at 1 kHz and at 10 kHz it’s the same thing, the difference is 0.3 - 0.5 μH. Moreover, such an effect is observed only on dumbbell-type inductors, starting from 30-40 μH, I have checked with others now, there is no noticeable difference.P.S. I understood the dimensionality: if you hold the tweezers perpendicular to the coil axis, you get this effect. If along the axis, it measures the same.

author: koendv
author_rank: Contributor
timestamp: November 01, 2024, 06:43:57 am
content: This looks like an eminently hackable device. Does anyone have a dentist in the family who could take an x-ray of the pcb?

author: Exosia
author_rank: Contributor
timestamp: November 02, 2024, 01:10:24 pm
content: I must admit, this is one of the most useful little tools I’ve ever purchased

author: miegapele
author_rank: Contributor
timestamp: November 17, 2024, 01:30:02 pm
content: This has interesting resistor raging.Most ranges are 10,000 counts. starting from 999.9mΩ to 99.99kΩ. However next range is only 900.0kΩ (strange). And then higher ranges are 1.99MΩ and 20.0MΩ (only 200 counts)

author: koendv
author_rank: Contributor
timestamp: December 28, 2024, 11:34:34 am
content: Soldered spring pins on the tweezer tips. Easier for measuring small components.Perhaps it would be better if the spring pins were slightly angled inward.Also, this is an opportunity to reduce cost: make a slot in the tweezer leg pcb. Solder the spring pin holder in the tweezer leg. Custom tweezer tips no longer needed,

author: Paul T
author_rank: Regular Contributor
timestamp: December 28, 2024, 01:53:13 pm
content: Quote from: koendv on December 28, 2024, 11:34:34 amSoldering a pogo pin socket in parallel and exchanging out tips is an excellent idea I've been using for a while. The cheap capacitor test pens come with raw brass or nickel plating. They are awful to use. By the time you squeeze hard enough the component goes flying. The pictures below show different pins (soldered directly without the socket) as an example of such a upgrade.A gold-plated spring probe can be used straight (compressing the pogo pins), or sideways (better to use pogos with a shorter throw). I sort of wished they made a medieval-ball-and-spikes club style pogo or ribbed to act like the FNIRSI.It's truly amazing how much better gold makes contact than these other surfaces. The force required to make electrical contact is reduced by about 25X. This is why I was dismayed when I saw how fast the MD1's tips lost their gold and was down to bare nickel. The plating's gold layer adhesion just wasn't good and led to flaking demise. They should seriously consider a quick-change pogo type solution.Side note: The other thing about these SMD tweezer pens is their propensity to break a connection inside when the cord rotates relative to the body back and forth.It fatigues the wires where they are soldered. Some hot glue on the end prevents the spinning.I add this as soon as I receive them.

author: u37
author_rank: Newbie
timestamp: December 28, 2024, 07:23:13 pm
content: At one time I tried to use pogo pins as a "contact" tool in my LCR, and gave up. The problem is not even in the poor contact surface of the pogo pins, the problem is more serious. When the mood takes you, measure the input-output resistance of the pogo. If you did not feel the horror, then squeeze it and repeat the measurement. Press it in different ways. Using pogo pins in LCR is (like cats being naughty in slippers).It is curious that I had 4 pogos, Kelvin connection, and still the damage was great. Here they offer "simple non-compensable" nonlinearity.Think about whether it is worth ruining even such a product.

author: Paul T
author_rank: Regular Contributor
timestamp: December 28, 2024, 08:29:39 pm
content: True about that. You need to carry the 4-wire setup through the pogo pins because they can be "scratchy" inside.Here's an example of standard test leads with piggyback pogo and a bunch of heat shrink tubing. See pictures attached.The shorter sharp metal object on each pen is the non-moving sharp stainless steel tip from the original leads (sense). The shiny part is a movable gold pogo pin, set to be longer than the stationary probe (force).The measurement method is to push on the pad with the primary post and to make sure the longer pin also hits the pad at the same time. The little bit of deflection of the longer probe moves it off of it's seat and assures a good connection in parallel with the one you are delivering with finger force.If you can connect with the secondary attachment for each probe in the MD1, you could accomplish the same thing. The standard probe is the stationary one, and the piggyback probe is the second wire of each lead which undergoes some deflection.The trick is to get them close enough that the measurement technique is not encumbered by making simultaneous attachment.

author: koendv
author_rank: Contributor
timestamp: December 29, 2024, 07:20:49 am
content: Some weeks ago I managed to short two adjacent pins while measuring. The board died. I ended up ordering new components and reworking. That is the day I decided my tweezer tips were going to be smaller.

author: Quincy
author_rank: Newbie
timestamp: February 05, 2025, 04:32:50 am
content: I acquired also one of these tweezers due to cost-effectiveness.It came with firmware V1.8 pre-installed and I just checked it out a bit:While I was playing around it always switched off after the set timer even when I just had been measuring something. The timer seems to reset when pushing buttons e.g. switching frequencies or modes and using "hold", though. Some more activity detection during active measurement would be useful IMHO, to have some "switch off when forgotten" functionality instead of "limit my measurement time in same mode" one. So I have to turn this function off until the Zoyi software engineers think the same...

author: Paul T
author_rank: Regular Contributor
timestamp: February 05, 2025, 11:39:00 pm
content: Typical for devices to look for proof of life as a button press or something else that clicks.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: February 06, 2025, 05:21:53 pm
content: Size Compare with the other 2 cheap LCR tweezers where the tip-spacing is quite a bit wider on MD1.LINK1S, MD1 & ST1None of the other seems to go as low as MD1, but they also got finer tips.

author: BrianR
author_rank: Newbie
timestamp: February 23, 2025, 05:43:45 pm
content: I have tried to like these but am seeing an issue when set to Capacitor reading. It bounces around with nothing connected. Reached out to the company for a reply ....https://imgur.com/gallery/broken-tool-EQAwNho

author: Paul T
author_rank: Regular Contributor
timestamp: February 28, 2025, 11:01:33 pm
content: Quote from: BrianR on February 23, 2025, 05:43:45 pmIn the auto mode, it's reporting OL, which indicates there isn't a valid connection for evaluation. When you switch to a dedicated mode, it's going to do it's best to try to report a value for you, reporting the effects of environmental noise. Do you have problems with terminated measurements? Your unit looks fine to me.

author: andre3d
author_rank: Contributor
timestamp: May 16, 2025, 01:25:01 pm
content: New firmware has arrived v2.0 .Update: 1. Added 0.1V measurement gear; 2. Added Z and X sub parameters.New button control.Delete ".txt"

author: Paul T
author_rank: Regular Contributor
timestamp: May 16, 2025, 01:27:28 pm
content: After this upgrade to v2.0 the data log is corrupt even if I reformat the drive!I am using safe eject and checkdisk only deletes the record.txt.Went back to v1.8 and everyting is OKI was able to read Record.txt one time (forgot how I did it) and Rs was not logged... still.Also, this 2.0 release does not have beep on diode (never has)I'm going to start recommend the FNIRSI if ZOYI can't get their sh1t together.

author: Aldo22
author_rank: Super Contributor
timestamp: May 16, 2025, 02:23:23 pm
content: @Paul T: Can you upload version 1.8 here?I'm not sure I've saved it and won't upgrade until I know I can go back.Thank you!

author: Paul T
author_rank: Regular Contributor
timestamp: May 16, 2025, 02:27:21 pm
content: @Aldo22Drop the .txtDisclaimer to all - I'm not responsible for the contents of the file. Use at your own risk

author: Aldo22
author_rank: Super Contributor
timestamp: May 16, 2025, 02:45:46 pm
content: Quote from: Paul T on May 16, 2025, 02:27:21 pmThank you!How does your problem manifest itself?I have now done the update and the logging seems to work.Previously I had 7 measurements from V1.8 and now I have measured a 50Ω load resistor and the measurement is there under point 8Code:No. Type Level Frequency Value D1 R 0.6V 1000Hz 11.4mR 18.54702 L 0. 6V 1000Hz 88.77H 43.14543 C 0.6V 1000Hz 963.6uF 0.39124 C 0.6V 1000Hz 964.9uF 0.38995 C 0.6V 1000Hz 8.5pF 0.58226 C 0.6V 1000Hz 48.47uF 0.19097 C 0.6V 1000Hz 3.8pF 1.10698 R 0.6V 1000Hz 50.37R 392.4744

author: Paul T
author_rank: Regular Contributor
timestamp: May 16, 2025, 02:55:03 pm
content: I double click on record.txt and windows tells me the file is corrupt an I must run chkdsk

author: Aldo22
author_rank: Super Contributor
timestamp: May 16, 2025, 03:25:09 pm
content: Quote from: Paul T on May 16, 2025, 02:55:03 pmI don't know, I'm on Linux and everything works here.I also deleted the record.txt content. No problem.I'm rather positively surprised that you still get new features for a $20 device months later, such as 100mV measurement.I still have to read up on what Z and X are good for, but that's great!EDIT: Attached 100mVrms/1kHz setting.

author: Atlan
author_rank: Frequent Contributor
timestamp: May 17, 2025, 07:34:23 am
content: Why doesn't it save the last settings?

author: Aldo22
author_rank: Super Contributor
timestamp: May 17, 2025, 08:26:52 am
content: Quote from: Atlan on May 17, 2025, 07:34:23 amI'm not sure if I wanted that.Just because I measured a capacitor at 100Hz last time doesn't mean I don't want to measure a resistor at 1kHz next time.It always starts with Auto/1kHz/600mV.

author: Aldo22
author_rank: Super Contributor
timestamp: May 17, 2025, 08:32:54 am
content: Since the terms are getting confusing for me, I googled a list here, but I think it's AI.Is that correct?Rs (Equivalent Series Resistance):The resistance component of the impedance, often displayed in a series equivalent circuit model.D (Dissipation Factor):Dissipation factor is a measure of the power loss in a component. It's calculated as the ratio of the resistive part of the impedance (real part) to the reactive part (imaginary part), essentially the ratio of energy dissipated to energy stored.Q (Quality Factor):Quality factor is the inverse of the dissipation factor (Q = 1/D). It indicates how well a component stores energy without dissipating it. A high Q value means a good quality factor, indicating a primarily reactive component with little energy loss.Z (Impedance):Impedance is the total opposition to the flow of alternating current (AC) in a circuit. It's a complex value, meaning it has both magnitude (resistance) and a phase angle relative to the applied voltage, indicating how much the current is "out of sync" with the voltage.X (Reactance):Reactance is the component of impedance that opposes the flow of current due to inductance (for inductive components) or capacitance (for capacitive components). It is the imaginary part of the impedance.

author: tautech
author_rank: Super Contributor
timestamp: May 17, 2025, 08:34:17 am
content: Quote from: Aldo22 on May 17, 2025, 08:26:52 amSure but others expect this especially when power saving functions put the tweezers to sleep.With a single button press they should wake up as you last used them.

author: Aldo22
author_rank: Super Contributor
timestamp: May 17, 2025, 08:49:18 am
content: Quote from: tautech on May 17, 2025, 08:34:17 amThat would certainly be nice (An option: “Start with last settings”, “Start with default settings”), but on my priority list, it would be behind the wish to log all secondary parameters (Rs, X, Z).

author: Martin72
author_rank: Super Contributor
timestamp: May 17, 2025, 08:51:49 am
content: Quote from: Aldo22 on May 17, 2025, 08:32:54 amYes.There is another useful diagram for the ESR, which also shows impedance.Basically, LCR meters always measure impedance and calculate the values accordingly.

author: Aldo22
author_rank: Super Contributor
timestamp: May 17, 2025, 09:23:00 am
content: Thank you!Quote from: Martin72 on May 17, 2025, 08:51:49 amDo I understand correctly that in this case "Z" is “raw data” for the LCR meter, which does not directly give me any additional/useful information about the DUT?

author: tautech
author_rank: Super Contributor
timestamp: May 17, 2025, 09:38:46 am
content: Quote from: Aldo22 on May 17, 2025, 08:49:18 amNeither is required with a well designed menu and measurement type selection process.Boot as last used is standard/normal.Research how ST42 tweezers work, pretty much as standard in the professional smart tweezers industry for near 2 decades.

author: Martin72
author_rank: Super Contributor
timestamp: May 17, 2025, 10:58:05 am
content: Quote from: Aldo22 on May 17, 2025, 09:23:00 amExactly.The Keysight/Agilent “Impedance Measurement Handbook” provides a good insight into this topic in the first two chapters.https://assets.testequity.com/te1/Documents/pdf/keysight/impedance-measurement-handbook.pdf

author: Atlan
author_rank: Frequent Contributor
timestamp: May 17, 2025, 11:11:37 am
content: Does it save by pressing HOLD? And the data is written to the file when the device is turned off. I formatted MD1 as FAT. WIN11 does not report a problem. fw2,0

author: Aldo22
author_rank: Super Contributor
timestamp: May 17, 2025, 02:51:06 pm
content: Quote from: tautech on May 17, 2025, 09:38:46 amOK, still, that's not something that bothers me about these $20 LCR Tweezers.I think the device has a lot to offer for the price.If such details were important to me, I would spend more money on a more comfort-oriented device.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: May 17, 2025, 04:17:54 pm
content: Quote from: Aldo22 on May 17, 2025, 02:51:06 pmIt would likely bother you, if you only had one button, and you had to cycle around with that single click-jogstick as on ST42 lite, on a tiny graphical display, though you can combat that with a good UI, and according to users it seems to be the case on ST42 lite.but these modern LCR tweezer got a decent size RGB LCD display with numerous buttons, so I don't have an issue that MD1 and ST1 start up in 1K 0.6V Auto.The QPLCR LINK1S that unit does save your settings., so it will start up in fx 100 kHz 0.1V if that was the parameters you last used..

author: indman
author_rank: Super Contributor
timestamp: May 17, 2025, 04:59:23 pm
content: Quote from: Aldo22 on May 17, 2025, 09:23:00 amThis is a distorted understanding. ImpedanceZis the same important parameter as all the others that you listed above.It is especially indicative in the sound industry, for example, it is very important to know the impedanceZof headphones or acoustic speakers.

author: Martin72
author_rank: Super Contributor
timestamp: May 17, 2025, 05:05:51 pm
content: QuoteI have ST42 tweezers and the joystick control takes a little getting used to at first, but after about five minutes you can operate the tweezers blindly with your thumb.

author: Aldo22
author_rank: Super Contributor
timestamp: May 17, 2025, 05:42:20 pm
content: Quote from: indman on May 17, 2025, 04:59:23 pmIn this context, yes. That's why I worded it a little carefully.With these tweezers, SMD components come to mind first, rather than speakers.But i tried it out with my loudspeakers (6Ω) now.100Hz: Z = 20.9Ω1kHz: Z = 10.42Ω10kHz: Z = 7.4ΩWhat does this tell me? Are these plausible values for a speaker declared as 6Ω (Nominal Impedance)?

author: Martin72
author_rank: Super Contributor
timestamp: May 17, 2025, 06:03:44 pm
content: This can also refer to the lowest or average impedance, but this is a topic that should be discussed separately, e.g., in the general technical chat area.

author: indman
author_rank: Super Contributor
timestamp: May 17, 2025, 06:10:30 pm
content: Quote from: Aldo22 on May 17, 2025, 05:42:20 pmThis indicates that the Z value for headphones differs at different frequencies and this is an important parameter.This also indicates that the standard for measuring Z in acoustics is 1kHz.I agree that this is a separate topic for discussion.

author: Paul T
author_rank: Regular Contributor
timestamp: May 20, 2025, 09:59:01 am
content: According to the video for 2.0 firmware, it specifically states the user will need to do a resistance calibration!What about people who don't have the proper resistors?!?!? :'(https://zotektools.com/products/zoyi-zt-md1/Evidently the file system is a windows 10 problem. Anyone else have the problem?

author: Simmed
author_rank: Frequent Contributor
timestamp: May 20, 2025, 10:21:05 am
content: Quote from: Aldo22 on May 17, 2025, 05:42:20 pmit would be interesting to be able to export a plot

author: Aldo22
author_rank: Super Contributor
timestamp: May 20, 2025, 12:45:14 pm
content: Quote from: Paul T on May 20, 2025, 09:59:01 amGood question and thanks for bringing it to my attention.I have been able to adjust the most relevant ranges with my cheapreference board(0.1%).For 1R and 1M I used 1% SMD resistors and for 10M I connected a few resistors together and compared the value with the ZT-225.That should be good enough.

author: DaneLaw
author_rank: Frequent Contributor
timestamp: May 20, 2025, 02:36:04 pm
content: Which values do it ask for, beside 1R and 1M and 10M.?And is it only 0.1V it calibrates, though likely not, since it seems to be the main calibration menu it asks for in this crude video.How deep is the calibration on MD1? Will it be overwritten by "restore" that will take it back to fx system cal values?Positive to see that they keep bringing out new FW and even implementing new features, that is far from the norm on cheap Chinese products..

author: Aldo22
author_rank: Super Contributor
timestamp: May 20, 2025, 03:16:03 pm
content: Quote from: DaneLaw on May 20, 2025, 02:36:04 pmThis is in the manual:Quote from: manualHowever, you can also skip values if you do not have a reference.Quote from: DaneLaw on May 20, 2025, 02:36:04 pmQuote from: manualQuote from: DaneLaw on May 20, 2025, 02:36:04 pmAbsolutely!

author: Aldo22
author_rank: Super Contributor
timestamp: May 20, 2025, 05:29:14 pm
content: Quote from: Paul T on May 20, 2025, 09:59:01 amI just tested it on Win10 and it can read the file.You said you reformatted the drive.Did you do that with Windows?

author: Paul T
author_rank: Regular Contributor
timestamp: May 21, 2025, 01:52:48 am
content: Yes. I accept the windows default FAT.

author: Aldo22
author_rank: Super Contributor
timestamp: May 21, 2025, 06:01:48 am
content: Quote from: Paul T on May 21, 2025, 01:52:48 amYou could try FAT16.By entering "format X: /FS:FAT/Q" at your command prompt, where X: is the drive letter of your USB flash drive, you may format the disk to FAT16.https://recoverit.wondershare.com/file-system/format-usb-to-fat16.htmlI don't know, but mine reports as FAT16 (vfat) on Linux.EDIT: Or 12 bit?I get the following output from linux command "sudo file -s /dev/sdd"/dev/sdd: DOS/MBR boot sector, code offset 0x3c+2, OEM-ID "MSDOS5.0", Bytes/sector 2048, reserved sectors 2, root entries 512, sectors 128 (volumes <=32 MB), Media descriptor 0xf8, sectors/FAT 1, sectors/track 1, heads 1, reserved 0x1, serial number 0x96a971be, unlabeled,FAT (12 bit)

author: Paul T
author_rank: Regular Contributor
timestamp: May 21, 2025, 07:07:09 pm
content: My device is now in a moving box. I hope they sort out the issue and I can try again in a couple months. Hopefully there will be a v2.1.One of the first things I will do is check to see how badly the resistance calibration went out of whack.Basically v1.8 was stable, and v2.0 ruined the factory accuracy and made the logging unusable. Therefore I recommend any shopper buy FNIRSI. The grooved leads are don’t make radial lead devices spin during test, and that one feature has led me to prefer it more recently.

author: Aldo22
author_rank: Super Contributor
timestamp: May 21, 2025, 07:37:59 pm
content: Quote from: Paul T on May 21, 2025, 07:07:09 pmAren't you being a little negative now?Does anyone else have problems with the file system?I'm still happy with the Zoyi for the price.I also think it's great that you can calibrate it yourself.The resistance measurements are now very repeatable.No.Type Level Frequency Value D1 R 0.6V 1000Hz 1.013R 832.11982 R 0.6V 1000Hz 9.995R 538.50123 R 0.6V 1000Hz 100.0R 1563.22394 R 0.6V 1000Hz 1.000kR 400.00755 R 0.6V 1000Hz 10.00kR 4459.74466 R 0.6V 1000Hz 100.0kR 255.8525

author: Paul T
author_rank: Regular Contributor
timestamp: May 21, 2025, 11:45:53 pm
content: Fair enough. At least it’s not bricked!

author: Atlan
author_rank: Frequent Contributor
timestamp: May 29, 2025, 01:19:49 pm
content: New firmware 29.5? MD1http://www.szzotek.com/h-col-159.html

author: Aldo22
author_rank: Super Contributor
timestamp: May 29, 2025, 01:38:56 pm
content: Quote from: Atlan on May 29, 2025, 01:19:49 pmI don't think so.The JPG contained in the zip shows V2.0.

author: dmitrkov
author_rank: Contributor
timestamp: May 30, 2025, 05:01:24 am
content: Got a reply under the video from Zoyi about the need for calibration after upgrading to version 2.0Quote

author: Paul T
author_rank: Regular Contributor
timestamp: June 01, 2025, 12:11:29 pm
content: Re:Version 2.0 is the final release. Unless any bugs are discovered, there will be no further updates.I found some!Failure to boot drive with Windows,Export data missing Rs parameter.Plus, add beep on diode recognition.Please don't look away!

author: Aldo22
author_rank: Super Contributor
timestamp: June 01, 2025, 12:59:08 pm
content: Quote from: Paul T on June 01, 2025, 12:11:29 pmHas anyone confirmed your file system issue in the meantime?Quote from: Paul T on June 01, 2025, 12:11:29 pmThose are feature requests. I don't think that's going to happen.

author: hapless
author_rank: Regular Contributor
timestamp: June 27, 2025, 12:44:29 am
content: Tried connecting to a Windows 11 machine. On v1.8, pressing HOLD takes a snapshot, but, instead of turning off the device, it seems to be enough to unplug USB and plug it back in to be able to read it. The data file isappendedevery time, probably to minimize wear on the flash. Making the mistake of deleting the file forces the device create an invalid file that can't be read by text editors. Andchkdskremoves it. This is seems like a reliable way to reproduce the problem, at least for me. Reformatting using FAT does not help. Sothat'sdefinitely a bug.The way around it that works for me is to format using something other than FAT (I use exFAT) and reconnect. At this point the OS will ask to format the drive again like the first time, and the MD1 creates a valid log file again. I have not tried v2.0.As for feature requests... I really wish the meter would have some indication during HOLD when the measured data differs much from what's on the screen. Seems like an easy thing to program. (Being careful what I wish for though, since a bad implementation would have it beeping incessantly.)

author: gadgetmind
author_rank: Newbie
timestamp: August 31, 2025, 08:30:22 am
content: Hi, new member here.Thanks to everyone for a very informative thread. It's taught me a lot about my MD1s, but sadly at a time when the have developed a fault. They do odd things at low resistances, particularly with low voltages, and they show 0.5ohms with shorted probes at 0.6V and 3ohms at 0.1V. This won't calibrate away as they don't calibrate on anything < 10 ohms and I get a "NG" error almost immediately.Their failures coincided with me lending them to someone at a Repair Cafe to test caps on a TV PSU board, so they might have had a zap, or this might be a coincidence. Who knows.I have opened them up, worked through the circuit a bit, and have ordered some likely parts. The most likely to be dead is the INA286 instrument amplifier (marked IPDI) so I'll do that first. There is also a PGA113 programmable gain amplifier (marked P113) and a RS8552 dual op amp. I kind of assume the op amp is for the output side of things, but I don't really know.There are then SOT-23-5 devices marked LLVP and BKA, and some small 10-pin devices (four down each side, two at the ends) marked DSR, and I haven't worked out what any of these are or what they do.I've ordered anohther MD1 but will try and fix my old ones even if I then donate them to someone. I'll report on progress.Oh, and yes, I'm also gutted that V2 didn't include a diode beep. :-(

author: gadgetmind
author_rank: Newbie
timestamp: August 31, 2025, 08:32:51 am
content: I should also add that I've used my scope (Zoyi ZT-703S) to check the voltage on the probes, and I get close enough to 0.1V, 0.3V and 0.6V RMS to be happy that the output side of things is working.

author: Paul T
author_rank: Regular Contributor
timestamp: September 02, 2025, 02:23:41 am
content: I can't figure out the proper button-press sequence calibrate the resistances. The Zoyi-provided video is not helpful at all to me.I get frustrated with the poor results and just keep setting it back to factory settings.Interesting thing, this restores it's previous accuracy. Which is quite good.If anyone can put forth a good description or has found a more detailed video, please let us know! I'd like to master this just to see how perfect I can get the unit. If successful I might blog about my success or lack thereof.

author: Aldo22
author_rank: Super Contributor
timestamp: September 02, 2025, 08:46:59 am
content: Quote from: Paul T on September 02, 2025, 02:23:41 amI use the following descriptions for the buttons:LEFT: Left Button ("Left Arrow Key")MID: Middle Button ("Right Arrow Key")RIGHT: Right Button ("Power Button")- Long Press MID to enter Menu- Repeat MID until "Calibrate" is highlighted- RIGHT: Select "Calibrate"- MID: Select Range- LEFT: Start Calibration -> During calibration, you will see “Start” -> Image1- Wait approx. 20 seconds until calibration is complete -> OK -> Image2- RIGHT: Exit- Long Press MID: Exit MenuSee also the manual:Quote

author: Paul T
author_rank: Regular Contributor
timestamp: September 02, 2025, 10:26:21 am
content: Thanks Aldo22! I think the problem is getting a stable resistance for the 20 seconds. Mine keeps "failing". On their video, they have a fixture which has gold plated posts and lots of plastic holders to keep the device stable. I'm trying to hold things together with my fingers for 20 seconds and it likely succumbs to noisy connection. I'm going to have to make something up (wishing I had 3D printer). Perhaps I can trace the foam in the case.

author: Aldo22
author_rank: Super Contributor
timestamp: September 02, 2025, 10:30:32 am
content: Quote from: Paul T on September 02, 2025, 10:26:21 amSince I damaged my first one mechanically, I bought a second one.This one came with v2.0, so I don't actually have to calibrate anything.

author: Paul T
author_rank: Regular Contributor
timestamp: September 02, 2025, 10:47:45 am
content: I usually put a solid rod with gold-plated surfaces between the tips for a short. Here is the fixture they show in their video short.

author: lapinc
author_rank: Newbie
timestamp: September 02, 2025, 11:51:03 am
content: Is it possible to upgrade/convert this type of tweezers to the 4-wire measurement? I mean, if I am not mistaken, the AC source and voltage sensing terminals are connected to the same pair of probes, but what if we connect Kelvin clamps directly to the terminals in order to improve accuracy and stability in the low resistance region? Am I missing something?

author: Paul T
author_rank: Regular Contributor
timestamp: September 02, 2025, 02:27:52 pm
content: In theory you could convert the device to 4-wire Kelvin by removing the arms and soldering in kelvin clips. However, the capacitance and inductance of the wires may alter the results.See Kerry’s video near the endhttps://youtu.be/Lt-Pi3PwyZs?si=SKMgz89dBNUWLwEc

author: lapinc
author_rank: Newbie
timestamp: September 02, 2025, 03:14:10 pm
content: Quote from: Paul T on September 02, 2025, 02:27:52 pmI just thought that maybe it would be even possible to place somewhere a small connector like USB C or 4-pin 3.5mm audio jack to have an option either to connect Kelvin clips or to use the original probes. But indeed, the distortion in C and L measurements may be significant. The resistance measurements don't seem to be affected though.

author: iet
author_rank: Frequent Contributor
timestamp: September 02, 2025, 06:09:34 pm
content: Quote from: lapinc on September 02, 2025, 11:51:03 amTake a look here. You might find this interesting.https://www.eevblog.com/forum/oshw/lcr-tweezers-open-source-project/

author: andre3d
author_rank: Contributor
timestamp: September 08, 2025, 04:19:58 pm
content: MD1 next generation ZOYI ZT-MD2https://www.bilibili.com/video/BV1keekzfEAo/?spm_id_from=333.788.recommend_more_video.-1

author: bffargo
author_rank: Regular Contributor
timestamp: September 09, 2025, 09:03:23 pm
content: Looks like the same interface as the Alientek LT1 one I just picked up from AliExpress (Sweep test page and the wave generator). It hit ~$25USD after shipping with all the coupons + coins last month, now about twice that.https://www.aliexpress.us/item/3256809275828514.html

author: Paul T
author_rank: Regular Contributor
timestamp: September 09, 2025, 10:13:21 pm
content: For the AlientekAdds 120 Hz (but not 100kHz)Adds sweep test frequenciesAdds 1V (good for diodes)Adds voltage measurement up to +/- 5 VAdds series or parrallel test modesAdds signal generatorAdds auto-rotate 180 degreesReally good upgrade!

author: Paul T
author_rank: Regular Contributor
timestamp: September 09, 2025, 11:02:05 pm
content: Yeah thes specs are much different than the Alientek

author: Paul T
author_rank: Regular Contributor
timestamp: September 10, 2025, 10:23:40 am
content: These images show the frequencies, the band scan feature, and the signal generator.

author: bffargo
author_rank: Regular Contributor
timestamp: September 21, 2025, 07:44:08 pm
content: Version 2.1 is now available, released 3-SEPT-2025http://www.szzotek.com/h-col-159.htmlLook for: "MD1固件2025.9.3.zip"File contents:ZT-MD1_ZOYI.bin Bytes: 102,920 CRC: 5D670C36

author: Paul T
author_rank: Regular Contributor
timestamp: September 21, 2025, 07:49:27 pm
content: Hmmm. It's not being shown at the normal place yet.https://zotektools.com/products/zoyi-zt-md1/I'm not ready to get excited about this release. According to the log, it simply fixes the low battery icon that shows up for 1 second while booting.

author: Aldo22
author_rank: Super Contributor
timestamp: September 21, 2025, 09:22:46 pm
content: I installed v2.1.I think it only fixes the minor bug with the battery icon after startup, which was introduced in v2.0.I don't think this update is essential.

author: Paul T
author_rank: Regular Contributor
timestamp: September 27, 2025, 03:26:10 am
content: In my case, record.txt is now functioning in V2.1. Previously, V2.0 produced a corrupted text file that could not be opened.However, Rs is still missing in the log.

author: FantaBH
author_rank: Newbie
timestamp: September 27, 2025, 12:36:20 pm
content: I have them long time already. Using them very often. They are quite precise with what they doing. So far compared their measurement with more trusted different instruments and they never failed me. I love them more then zoyi DQ2 LCR meter. Tweezers are more easy to use, faster to use then dq2 with all constant need for calibration to be able to read different measurements.