How would I go about measuring an analog signal on my arduino mega that has both positive and negative voltages
Here is my try at this: if your voltage source doesn't mind sinking
something like 150&nbsp;µA, you could try something like this:







simulate this circuit &ndash; Schematic created using CircuitLab

This should map the input range [−70&nbsp;mV, +50&nbsp;mV] to
[0.04&nbsp;V, 4.06&nbsp;V].