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[Question] Precision Voltage and Current Measurment ways for E-Load

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IamSynthetiC:
Greetings,

I have recently received an Electronic Load Kit from eBay, very standard stuff as eBay electronic loads go. But, in the past few days i have been trying to design an arduino centered controler with en external precision ADC and DAC mounted on a custom-build-pcb aruino mega. it is a big project all-around, and as it is still at its infant stages, any ideas are free to be as "destructive" as they need to be.

The features i want to implement are the following:

* Temprature Monitoring.
* Fan speed control.
* Interfacing and Data-logging.
* Precise Voltage and Current measurment.
* Software controled CV,CP,CR Modes.
* Varius safety features.
Before i describe my problem, i need to point out that i am a beginer, and i need to be treated as such. (google has allready filled my mind with fancy electronic terms and words that i do not understand, i feel like i had enough :D).

My problem lies in the voltage and current measurment area. I want the load to receive voltages up to 30-40 Volts and perhaps 10 Amps (unlikely, i know).
I do not want to simply linearly scale the input to the ADC, as i feel it is "lazy" and lowers the resolution.
I have found and article named "Optimize High-Voltage Measurements with Self-Adjusting Attenuator", and the Self-Adjusting Attenuator
immediately cought my attention, as it seems to be everything i need.

link to article: https://www.electronicdesign.com/technologies/test-measurement/article/21801410/optimize-highvoltage-measurements-with-selfadjusting-attenuator

Allas, i have been googling the word Attenuator for the whole evening and i get nothing.
I have though about replicating the schematic, but the voltages and currents seem (to my undestanding) too much for the comparators, and the OpAmps. Wouldnt they just break? . And wouldnt such a design affect the current measurment ? (or the current measurment, would affect the voltage ?)
Pplus, all this talk about the impedance of the load completely goes over my head.)

So, to conclude. Is the self-adjusting attenuator a good idea? Is there any other good and reliable way to accurately measure voltage and current?

Thanks for you time.
Have a good day.

MasterT:
I think, the correct name is "folding adc architecture". Idea was around since 1956, according to Analog Device:
https://www.analog.com/media/en/training-seminars/tutorials/MT-025.pdf
Not really good, since it's just extending existing ADC resolution by 3 more bits, same time linearity of the analog circuitry has to be better than LSB, or 0.01% with arduino 10-bits internal ADC. Easier to use 18-24 bits SigmaDelta external converter and common Resistive Divider.

IamSynthetiC:
Thanks for the info. Folding ADC architecture does show more results on google, plus the link you provided is filled with information. I am going to to read more into them tomorrow.

Regarding the ADC, i forgot to mention i had already selected the TI ADS1262IPW Precision, 32-bit, ΔΣ ADC .( why 32bits? for further experimentation).
32-Bits are more than enough to measure voltages accurately accros the range of 0-50 V, therefore i'll have to aggree that a simple voltage divider is the simpest solution.
But i can not help but feel that it is an inelegant solution (even if it isnt). I feel like some of the resolution will be wasted, and while there is plenty of it to waste, i would like to have to option of preserving it with smaller ADC's.

Also, wouldnt a voltage divider change its behavior with a variable load ?


MasterT:
Not sure I understand a question. Voltage divider scales input range to norm acceptable by ADC.  Be realistic, resistive divider is usually most accurate part, well after calibration. There are more things susceptible to errors,  voltage reference, interference, temperature etc.
 How precise voltage measurements needs to be? Microvolts at 40V level?

IamSynthetiC:
I was talking about this :

am i missing something ? (link is : http://hyperphysics.phy-astr.gsu.edu/hbase/electric/voldiv.html)

As for the resolution, i really dont need microvolt range, millivolts are fine. I am asking though, for ways i can use the hole spectrum of an ADC for a set signal, outside of this project, for when using an arduino 10-Bit ADC for example.

For the voltage measurment i'll stick with the voltage divider as you have suggested.

For the current measurment, i am aware of two options.

* Some integrated sensor
* Shunt
I have worked with integrated sensors before on the arduino. I used an INA226 (CJMCU-226) module and it was extremely precise and accurate downt to the millivolts. The code however explained that the sensor is old and can take a measurment every 2-3 seconds or so. I tried taking data from it every 1 second but they would always arrive after 1.3 to 2 seconds. Data rate will play a major role in the software controlled modes, therefore i scrapped the idea of using this. Are there any other alternatives ?

*EDIT: The INA226 Datasheet clearly states that Convertion and Averaging times can be scaled from ms down to μs, so clearly i need to do some more research on the library i used to set these times.

As for the shunt method, it seems like a more complicated circuit based on a very simple principle. I have never worked closely with amplifiers before and i dont really know what to expect. I am waiting on some LM386 (audio amp), LM324N (Quad OpAmp) and LM393P (Dif-Comparator) ICs to play around with.

But until then, aren't these sensors/modules based on the same principle as the standaloen shunt? and if so, what are the advantages of building my own circuit, when i can get a specialized and optimized one for my type need ?

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