Zoyi ZT-MD1 - new LCR Tweezers

[slavoy]

I don't see any detailed specs yet. Just this short info, and the price $48

https://thedmm.com/shop/zt-md1/

[TheDefpom]

They are supposed to be sending me one to review... so watch this space :-)

[Phil1977]

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

[Aldo22]

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?

[Phil1977]

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.

[watchmaker]

Here is a video "review":

[iet]

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.

[indman]

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.

[iet]

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.

[indman]

Even taking into account the faulty capacitor and the different measurement principle, the difference of 234 uF is very large.

You 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.