Measurements in the nanohenry range. Tweezer FNIRSI ST2 and others.

[Gyro]

Where can you find inductors in the nanohenry range? One common source is circuit boards from various electronic devices. These inductors typically lack markings, so I rely on the board's component designations and the physical dimensions of the parts. If there is any doubt, I can verify the measurements using a different inductance meter.
3 nH inductor (0402).

Ls 2.9736nH  Rs 4.6835mR   


@Grandchuck, you really weren't trying were you!


@iet: You really need to develop an understanding of physical and mechanical properties materials and electronic component, you are so naive.  Just look up the temperature coefficients of resistance and thermal expansion of copper. I'm not going to bother working out the decimal places but you are probably going to need jaw positioning accuracy in the nm range and hold the temperature within the mK range to achieve those resolutions. [Edit: Also, measuring 3nH at 100kHz, seriously?

You need to develop a sense of scientific credulity.

[iet]

Just look up the temperature coefficients of resistance and thermal expansion of copper. I'm not going to bother working out the decimal places but you are probably going to need jaw positioning accuracy in the nm range and hold the temperature within the mK range to achieve those resolutions.

You are overcomplicating things. This isn't a NASA lab.These are standard measurements for this type of tweezer. The LCR Pro1 Plus model is an upgraded version of the LCR Pro1, specifically enhanced for the nanohenry range.
I was missing a 3 nH inductor, but now I can transfer it to the test board.
As for resolution, we should keep things in perspective—I notice some people getting a bit worked up about it. For me, a single digit after the decimal point is sufficient. If the display shows 2.9 nH or 3.1 nH, that is enough to gauge the inductance value.
The UT622C is even simpler in this regard; it displays 0.003 uH without additional digits. This corresponds to its resolution of 0.001 uH, or 1 nH.
I am not familiar with other tweezers that measure with a resolution of 0.01–0.001 nH, so I cannot compare nanohenry-range measurements with other devices. I hope such models appear in the future, perhaps if the Chinese brands we know develop a more advanced LCR tweezer with improved nanohenry capabilities.

[Gyro]

Unfortunately I'm not over-complicating things. The chances of accurately resolving +/- 0.1nH at 100kHz are pretty much zero. In fact I am skeptical of single digit nH readings.

Just as a scientific credulity exercise, what is the reactance of 0.1nH at 100kHz?... and how does it compare to the contact resistance variation of the probes?

[Grandchuck]

No one is overcomplicating.  Mawyatt has repeatedly asked for a test current measurement.  The point is that nH measurements in a small, battery powered instrument are mostly vapor and an insult to the art of metrology.
... and 5 digits of resolution

I will concede that small, battery powered VNAs can work well ... but forget about 5 digits of resolution.

[iet]

I am skeptical of single digit nH readings.

That’s why I use two inductance meters with identical measurement parameters: sine wave, 100 kHz, 1 V.
For me, measurement repeatability and stability are what matter.
I’d like to add that the UT622C is a very good LCR meter. It’s fast, has excellent calibration, and offers high stability. It works well with various fixtures and has fully met my expectations.

[iet]

I decided to run a rather specific test—purely as a hobbyist project, of course. The goal was to at least attempt to measure an inductance of less than 0.1 nH.
I used 0.08 mm wire. To verify the repeatability of the results, I performed measurements under different conditions.
The result in both cases was the same: 0.08 nH.

[iet]

A second LCR meter(UT622C), confirmed that it is a 3 nH inductor.