Schematic:
.-----------------.
| Arduino |
| |
| | Vminus
|pin_in_minus=A1 | --------o-----------.
| | | | R2=100000
| | | |\| | R1=10000
| | 100k '----|-\ | ___ ___
| | ___ | >---o--|___|--o---|___|---.
|pin_pwm_minus=D10|-|___|---o----|+/ | |
| | | |/| | |
| | --- | |
| | 100n --- MC33201 | |
| | | | |
| | | | |
| | === | |\| |
| | 100k GND '---|-\ |
| | ___ Vplus | >----o
| pin_pwm_plus=D9 |-|___|--o------o-------------------|+/ |
| | | | |/| |
| | --- | |
| | 100n--- | unknown |
| | | | |
| | | | |
| | === | |
| | GND | |
| | | |
| pin_in_plus=A0 |---------------' |
| | Vout |
| pin_out=A2 | ----------o---------------------o---------'
| | ___ | |
| pin_load_1=D12 | --|___|---o Rload_1=47000 --- C3
| | ___ | --- 1u
| pin_load_2=D11 | --|___|---o Rload_2=4700 |
| | ___ | ===
| pin_load_3=D8 | --|___|- -' Rload_3=470 GND
'-----------------'
C3 is needed if op-amp oscillates (e.g. CA3130)