The input is a matched differential (-/+) 1us LPF amplifier that needs matches short wires in a twisted pair to avoid AC hum pickup. You can go for maximum gain.
The Op Amp datasheet is here
Excellent dc performance (B grade)
- 50 μV max, input offset voltage (not resolution)
- 0.6 μV/°C max, input offset drift
- 1.0 nA max, input bias current
- 100 dB min ...
I didn’t manage to amplify the signal I need to amplify.
If you are talking about amplifying the coil signal (previous post) then I see where you possible went wrong. I've downloaded the schematic and added what you need to add: -
Basically, as I understand, you connected your coil directly across both inputs. If you do this then you need to add bias ...
In general, when amplifying small signals, you but the main gain stage first to get the signal up to a usable level. This makes the system more noise immune, and also (if the source is high impedance) performs impedance conversion.
In this case, reversing the order would mean connecting the source (looks like the human body in this case) directly to the ...