How Can I Measure Negative Voltages With Arduino UNO?

How Can I Measure Negative Voltages With Arduino UNO?

Connect a voltage divider to 5volt instead of ground.

Post the voltage (range) you want to measure, so we can give better advice.
Leo..

Wawa:
Connect a voltage divider to 5volt instead of ground.

Post the voltage (range) you want to measure, so we can give better advice.
Leo..

-1,0 e-4 approximately, I have to amplify the signal with a LF353

That opamp needs a dual rail supply.
Easier to use a single supply opamp with a common mode range that includes ground, e.g. LM358.

+input to ground.
Resistor#1 from output to -input.
Resistor#2 from “voltage to measure” to -input.
The opamp tries to make the -input the same voltage as the +input (ground).
A see-saw/teeter-totter with ground as a pivot point.

The resistor ratio is gain.
e.g. with two 2k2 resistors: -5volt in = +5volt out.
Change R#2 to 3k3, and you can measure (3k3/2k2) * 5volt = -7.5volt.

This opamp needs at least a 7volt supply to be able to output 5volt.
Leo…