good accuracy inductance meter using arduino (inductance measurement)

[pee-tr]

hi,

I know about the DE 5000 situation...
including that a usable (for guitar pickups) inductance meter need be designed for the purpose...

in any case, I've found DIY inductance meter using arduino...
(arduino is a fun thing, for sure, but sometimes it is only being sued to display a number, like in the case of a gauss meter using a HAL sensor -- which could be read using a DMM and a simple calculation, BUT in this case it seems to my layman eyes as a potentially good project... )

see the PDF: https://www.siliconchip.com.au/Files/Samples/Silicon Chip June 2017 p28-53.pdf
(opens in new window, and you can download it or just open it)

this webpage (another source) also describes this project, too (back in 2011, as a matter of fact):
https://reibot.org/2011/07/19/measuring-inductance/

my Question:
could this be used with pickups with reasonably good results?

they say in the reibot.org article:

"Now micro controllers are terrible at analyzing analog signals. The ATMEGA328 ADC is capable of sampling analog signals at 9600hz or .1ms, which is fast but no where near what this project requires."
which is great news, cause one cheap LCR meter (in fact, two) exists based on ATMEGA328...
so, this one must be better

also, they say in the Silicon Chip article:

"It offers automatic digital measurement of both inductance (L) and over a wide range and with 5-digit resolution.
Measurement accuracy is better than ±1% of reading over most of the ranges."



they say it has very high accuracy:

Features & specifications
Inductance range: ........................... 10nH
Capacitance range: ......................... 0.1p to 100mH+
F to 2.7μ F+ (non-polarised only) digits in either mode
Range selection: ............................. automatic
Sampling rate: ................................ approximately one measurement per second
Accuracy (when calibrated): ........... ±1% of reading, ±0.1pF or ±10nH
Supply voltage: ............................... 5V
DC @ <65mA (including backlit LCD)
Supply type: ................................... USB
charger or the USB port on a PC

[Helmholtz]

An inductance range of 10nH doesn't make sense. Even a short piece of wire has more inductance than that.

Typical PU impedances are between 2H and maybe 6H, so a range of 10H should be fine for most PUs.

[pee-tr]

thank you,

I was superficial enough not to realize that nano thing
but it is up to 100mH and more... almost there... "100mH+"

I still hope the project is viable...

on the other page, I read:
"then this method is definitely not for you due to parasitic capacitance, which isn’t taken into account"

does this apply for us?

[Helmholtz]

on the other page, I read:
"then this method is definitely not for you due to parasitic capacitance, which isn’t taken into account"

I understand the measurement principle works by calculating the inductance from the resonant frequency of the inductor with a µF capacitor.
As parasitic capacitance is in the pF range, it should not have a noticeable effect on the result.

but it is up to 100mH and more... almost there... "100mH+"

Well, 10H is quite a bit more than 0.1H.

[pee-tr]

thank you

EDIT:

sort of by accident, I've bumped into this project...
its inductance measurement range goes as high as 20H ...

https://www.electronics-lab.com/proj...nced-lc-meter/

[pee-tr]

conclusion
________________________________________________________ ____________



that link I'd posted yesterday turns out to be based on a Hungarian project, from 2009, called LCM3
see: https://www.hobbielektronika.hu/cikk...oseg.html?pg=7

and it is very well documented...
the developers used to sell it as a KIT, but only in Hungary (I happen to be Hungarian, as a matter of fact),

the developers did make the "hex code" available, several versions of it...
as I understand, it is "complied".. so, kit is not the source code... but binary...
these are available today, too...
also the parts list and the PCB plan...

the entire project is pretty transparent, and easily accessible...
I'm going to buy one as a one piece, fully finished product...

........................................................ ......................

EDIT:
I've been reading about it, and two absolutely competent guys explained that
it is NOT accurate when measuring inductance

one guy told about a test of a transformer that was for sure 4,7H...

• a DMM gave: 1.7H
• the LCM3: 1,3H
• LCR-4 (ATMEGA tester): 3,5H
• then he used 6,5 V AC and a resistor, and measured voltage drops, and made calculations, which gave him: 4,65H

I think I'll go for this latter method
I only have to learn how to

[Helmholtz]

[B]
right now I'm waiting for the key info whether of not this device can be used for our purposes...

An inductance accuracy of +/- 5% is not that great but should be sufficient.
It is essential that the measuring frequency is low. Must not be above 1kHz!

[pee-tr]

as you mentioned low measurement frequency as an important factor, I thought about the "transformer + resistor" resonant frequency method @ 50/60Hz...
and now I'm completely attracted to measurement methods like that... hoping to avoid buying a DE 5000

and on this page, they sample 4 (?), two simple ones and several sophisticated ones...

starting at figure 3.

(the text is obviously from 1968, and it is hard to read because it was (very probably) copied from a PDF file,
and spaces and hyphens went everywhere but it seems to be a very very good source, for all that)

I wonder what you think about the first two methods?
viable? make sense with pickups?

[Helmholtz]

The method shown in figure 3 would work, but involved formulas and calculations are awkward.
The method requires 2 resistance and 2 (better 3) voltage measurements and errors add.
E.g. transformer voltage varies with mains voltage.