I need to use my Arduino to check the output from this environmental sensor I have. It provides this output in the form of a voltage between -5v and +5v.
Based on my searching thus far an analog Arduino pin cant take the negative voltages. So I'm thinking I will need to wire up a circuit that splits the output signal and sends 0v to +5v to one pin on the Arduino and then inverts any 0v to -5v signals and sends them to a different pin.
Does that sound correct?
If so; can anyone point me to a circuit that will do this?
No
Although it might sound simple converting a +/- signal to a single ended one is not something you can do easily.
A lot depends on if you have access to the negative supply voltage and if it is floating with regard to the arduino. If it is and you have then connect the -5v rail to the arduino ground and pass the signal through a potential divider with equal resistors. However I suspect this is not the case for you.
So the positive and negative leads coming out of the black box sensor (that has its own power source) connect to the inputs on the left side of the diagram thereby sharing ground with the ardy? When it goes negative wont that be bad though?
As long as it's safe to connect the two grounds together, then you don't have to worry about it "going negative" as only the top connection point goes negative relative to the bottom one, which is assumed to be 0V on both systems. The Arduino (and the op-amp) will never see the negative voltage in this circuit since the op-amp keeps its input pins at about 1.66V.
Negative is a relative term When you say "positive" or "negative" it is always relative to some point that you arbitrarily denote to be 0V (commonly, and many say incorrectly, called "ground"). So by connecting "grounds" together we're just saying the 0V point on both systems is considered to be the same node in the circuit.
Now, without knowing more about the sensor, it's tough to say whether it's safe to connect grounds together. If the sensor is powered off a battery then it should be safe because it's floating.
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When you say "positive" or "negative" it is always relative to some point that you arbitrarily denote to be 0V (commonly, and many say incorrectly, called "ground"). So by connecting "grounds" together we're just saying the 0V point on both systems is considered to be the same node in the circuit.