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Error Chart Compilation: Inductance

Writer's picture: Paul TaylorPaul Taylor


Here's the results comparing the few inductance measuring devices I have. I hand picked coils which are evenly spaced on a logarithmic graph.


Below 100 uH, it was clear to me the East Tester ET431 handheld meter was doing the best. Best resolution, stability, and matched the markings on the components.


For most of the right side of the chart, the results from the most consistent devices were averaged. It seems the better of the tweezers is the ZOYI ZT-MD1. However, all these tweezers fail to provide sufficient resolution on the left side of the chart. The FNIRSI LCR-ST1 was a little less dependable for low inductance values.


The Joyit LCR-T7 component testers had some issues. 10% accuracy only occurs at 500 uH and above. Sometimes their are failures: Where there are 3 missing test points, the device reported the coils as diodes!


The Corestorm HU-053 didn't do too badly, despite being a kit build. It reports XXXXXXXXX.X uH, but only starts reading values above 1 uH. It is only potentially spot-on around 25 uH.


The first measured-error graph is +/- 50%.



The second graph drops isolates the better performers at +/- 10%:



These 4 units have selectable test frequency. The left side of the chart utilized 10 kHz up to 4,700 uH. The right side around 0.8 H and above was 100 Hz. Everything in between was 1 kHz. The ET431 also required appropriate selection of series or parallel bridge mode.


The ESR value (equivalent series resistance) was acceptably close for all the different devices that report this value. For the purpose of this presentation, only the inductance value was reported in microHenries. I noted that not only the inductance value is affecting by test frequency, the ESR can be very sensitive to test frequency as well.


For more accurate low inductance measurements, a 100 kHz test frequency is required. These units generally cost at least twice as much as their 10 kHz counterparts, and would be appropriate for someone working in the RF field.


That's all for today, I wanted to get this comparison out for to complement the other comparisons.

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