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Digilent Analog Discovery 2 as a resistance meter.

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PeterFW:
I am trying to build a improvised 4 wire resistance meter with a Digilent Analog Discovery 2 and i am wondering is i am missing anything obvious here or if this approach is terrible. 
This is just to learn and experiment, to see if this would be possible and how well it might work.
Basically i have 2 differential ADCs, a programable power supply and 16 digital IO pins that i can program.

My basic idea was to just buy a decent reference resistor on the power supply to get a somewhat stable and and adjustable current source. 

And ADC1 goes across my reference resistor, ADC2 across my DUT with proper kelvin probes. 
I can measure the current over my reference resistor and the voltage across my DUT. 

I found this  100 Ohms ±0.02% ±0.2ppm/°C resistor, bit worried that there is no solder profile in the datasheet but a standard temp profile should not disturb it too much. 
https://www.digikey.de/de/products/detail/vpg-foil-resistors/Y1630100R000Q9R/4231501

Already have a bunch or proper resistance meters around to check it against, to make some comparisons how well that works. 

Maybe a passive lowpass filter on the ADCs might not be a bad idea with a jumper to see how it impacts the measurements. 

croma641:
Peter,

Your solution is

->  https://www.eevblog.com/forum/projects/impedance-analyzer-build-and-experiments



->       (and all the other videos)




a pcb,  few € of components , fantastic solution for capacitors, resistor, impedances....


one of the most underrated project ever seen (100% working), super precise


bye

Andrea

egonotto:
Hello,

I think the accuracy of the voltage measurement of the Analog Discovery is not sufficient for a ±0.02% resistor.

WaveForms already has an impedance analyzer

Best regards
egonotto

croma641:

If advanced VNA correction algorithms are implemented, with an active plugin,  as in this case, the result is very different

"Impedance analyzer" was created to overcome the deficiencies of "Waveforms"

Please read the whole abovementioned thread.


regards



--- Quote from: egonotto on December 22, 2023, 07:23:56 pm ---Hello,

I think the accuracy of the voltage measurement of the Analog Discovery is not sufficient for a ±0.02% resistor.

WaveForms already has an impedance analyzer

Best regards
egonotto

--- End quote ---

G0HZU:

--- Quote ---one of the most underrated project ever seen (100% working), super precise
--- End quote ---
I agree. I've been using the AD2 and this SW (by TheStuffMade) for quite a while now.

I mainly use it to measure lumped components across LF through to about 100kHz.

It really is a great piece of work and I'm very grateful for it.

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