Hello every one!
I need to measure voltage with arduino analog pin, can anyone help with scheme with electrically isolated analog inputs of arduino?
Tell us exactly what you want to measure and your electronic/programming experience.
Weedpharma
Well, I want to measure signls with low intencity aproximetly 2mV-10mV, I use amp scheme to measure it(from data sheet from amp ina118), but I found that to achive good result I need isolated analog inputs. But I dont know how to do it. I can show my code to arduino to achiving high sample rate in my oscilope that works with RS232.
sketch_nov12k.ino (690 Bytes)
I do not understand what you are actually doing.
Give us a drawing of the circuit you are using and how you will be connecting everything.
If you are feeding this low level into an amplifier to give meaningful voltage levels, let us know.
Weedpharma
NikitaP:
but I found that to achive good result I need isolated analog inputs.
Where did you find this?
It is not true at all.
You are dealing with low level signals, but not really small signals, you say 2mV-10mV, so the op-amp can be used to increase the level of that input signal to something you can then read with on an Arduino analog pin.
What sort of sample rate do you need and tell us why?
Is fitering important to you, if so, how do you intend to do this, with a low pass filter on the op-amp, or in software?
You need to provide much clearer detail about what you have and what you wish to do.
Try not to skimp on short sentences, rather, provide as much concise detail as you can about what your project, otherwise we can only make assumptions and waste time asking you exactly what I am asking you now.
Paul
Well, you can not get much more shorter on words and cryptic than just suppling us a link.
It is good practice to describe what you link means, rather than again, letting us guess how it relates to your questions.
Right, so I finally found in the right side of the schematic a bit of writting there that says 'use and AD converer with electrical isolation'
And, also, you left it up to me to figure out why that is said.
The reason is that it is a circuit that is connected to teh human body, where electrical isolation is a requirement, but from my experience, only when your equipment is powered from a power source other than battery. That is, if it is connected in any way to the mains power.
Are you using this for measuring electrical signals from a human body?
NikitaP wrote:
but I found that to achive good result I need isolated analog inputs
This is still not true, you do not get good or better results if you were to have isolation, it is only there for safety.
Please explain what you have done in terms of tests and the results?
Have you tested this with a voltage calibration device where you set the volatge to represent the human body and then see what your Arduino gives as the result?
Paul
I use my laptop and program that i wrote like digit oscilope . Main reason is that I dont know should I do electrical isolation or not?
Second quastion is correct I conect outputs of the circuit to arduino?
I try to make zero point on scheme with simple divider of voltage and amp with negative supply.
but i didnt see anything only noise. Power supply with + and - of arduino.