I am using this stethoscope circuit
I want to give TL072 butterworth filter output to Arduino Due ADC which input is max 3.3 but the supply of the mentioned circuit is split +9-0-(-9) volts. How can I interface this?
I tried to shift reference voltages with two back to back diodes but it did not give output
My question is what is the best way to interface this circuit to arduino due ADC so that we can sample data there
Thanks
Best Answer
If you can modify your circuit, you can remove R15 and then take the output from C6 and add a simple DC bias circuit as described. C6 will already "isolate" the circuits. You have to make sure not to set R11 too high.
simulate this circuit – Schematic created using CircuitLab
If you can't modify the stethoscope circuit, then you can simply add another capacitor like C6 from the output, essentially like the circuit in this answer.