i would like to make a "voltmeter" to read from +2V to -2V and connect it to an Arduino ADC ( 0V to 5V ).
I found different configurations for do this job:
From this site:
Bipolar to unipolar converter, a summing amp:
The last approach use:
- instrumental amp
- full-wave rectifier
- low pass filter
- inverting opamp + gain
The signal i need to read it's "stable", the ECG circuit i suppose it's too complex for this job. But i'm interested to compare the instrumental amp Vs opamp.
What is the best configuration for my porspose?
For the Vref, I have this question:
In this video & this article are show how it works.
In the article he say, for example:
Vref at 5v -> 0-5 V has 4.9 mV resolution
Vref at 3.3v -> 0-3.3 has 3.2mV resolution
But in the video does not say that, he used Vref at 1.1v and apparently does not have any problem.... probably the solution is here in the code.