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Topic: how to measure negative voltage (Read 395 times) previous topic - next topic


Dear all,
I want to use arduino to read an output of photodector. But the output voltage is on the negative voltage range and depending of incident light is in the range from -100mV to -1V. How to convert the signal from negative to positive region, idealy via 1:1 invertor. I have read about inverting operational amplifier (op), and how a question about connection of op, photodetector and arduino. How do do such a connection and which op it is better to use?


A three-resistor voltage divider may work for you.

But a much smarter thing for you would be to post more details in your project, as outlined in the sticky that you apparently didn't read or ignored.
Quality of answers is related to the quality of questions. Good questions will get good answers. Useless answers are a sign of a poor question.


Jun 15, 2018, 10:20 pm Last Edit: Jun 15, 2018, 10:20 pm by GolamMostafa
You may try this op-amp circuit. 741 is usually operated on dual (+/- : +5/-5 or +12/-12) power supplies. However, it can also be operated in single supply to get expected result. The ouput of the op-amp could be connected with Channel-A0 of Arduino UNO.

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