An isolated analog input for Arduino

Giovanni Carrera designed a circuit that accepts input voltage from about 20mV to 5V or a current of 4 to 20 mA and converts it to a isolated frequency signal.

A voltage to frequency converter can realize an opto-isolated analog input for Arduino or other microcontroller systems. This circuit is particularly suitable for industrial control plants with 4-20mA sensors.

An isolated analog input for Arduino – [Link]