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Arduino Inductance measuring meter

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eskoilola:
Ok.

The circuit cannot easily measure inductances below 10 microhenries or so and be able to measure indutances in millihenry class. That assuming You have the same capacitor all the time. For millihenry class inductance the capacitance might be neglible and for millihenry class and under all too large. This has an impact on the accuracy.

The frequency injection might be difficult as then You had to generate the injection frequency. On the other hand this might enable You to figure out the Q-value of the inductor.

Another way of figuring of the Q-value might be to use Your suggestion but adjust the gain of the amplifier somehow. Then just figure out where the circuit starts to oscillate and there You have Your Q-value.

picclock:
A quick test and a small bit of code and its starting to look very good. Clear ring with well defined frequencies. Will definitely make for keeps and power with a lipo or lithium ion battery.

Capacitor was 5x1uF I found in my scrap box, already soldered together, measuring 5.21uF.

Should finish the software over the next day or two.

Best Regards

picclock

picclock:
Well its finished. Seems pretty good to me. 100uH inductor measures 100uH - highly suspicious but its for real, 4mH choke reads 4.31mH, small inductor reads 6uH no idea what its supposed to be but scope and frequency seem to indicate correct measurement, likewise small mains txfmr primary at 124mH. 

Original schematic has been amended to include input protection resisters.

Hopefully source code attached (you will have to remove the .txt extension to make it a .ino file type for the arduino IDE).

Best Regards

picclock

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