acs712-05B should produce 185mV each ampere; here I'm interested to a range of 0-3A so the purpose of amplification here is to increase the divisions that adc can see and for arduino is 1024 over a 0-5V range.
Follow lab results where Vin is the voltage produced by acs712, V1 is the voltage after first opamp stage (filtered), V2 is the voltage after second opamp stage.
LAB RESULTS
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without filter I had Vpp of 0.8 while filtering Vpp reduces to 0.1
using current = 0 ; 1 ; 2 ; 3 (A)
VOLTAGES
Vin = 2.51 ; 2.67 ; 2.83 ; 2.99
V1 = 0 ; 0.48 ; 0.97 ; 1.46
V2 = 0.3 ; 1.21 ; 2.27 ; 3.24
SLOPES
Vin = 0.16 ; 0.16 ; 0.16
V1 = 0.48 ; 0.49 ; 0.49
V2 = 0.91 ; 1.06 ; 0.97
FEATURES ( sensibility ; divs ; resolution )
Vin ( 160mV/A ; 98divs ; 30.5mA )
V1 ( 487mV/A ; 299divs ; 10.03mA )
V2 ( 980mV/A ; 602divs ; 4.98mA )
