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Topic: How to measure a small bipolar voltage? (Read 1 time) previous topic - next topic

renesis

Amazing!

Thanks a lot to you both!

I've calculated out the resistors, off to build the test circuit now.

Is there a particular op-amp I need? Or will a general one do? I take it I will need a negative voltage as well?

CrossRoads

Use a single supply op amp, like the LM358 on the Arduino boards.
http://www.ti.com/lit/ds/symlink/lm158-n.pdf

Want a 0-5V output when done to be compliant with Arduino ADC input.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

retrolefty


Use a single supply op amp, like the LM358 on the Arduino boards.
http://www.ti.com/lit/ds/symlink/lm158-n.pdf

Want a 0-5V output when done to be compliant with Arduino ADC input.



Is the LM358 a rail to rail op-amp? I don't think it is and that would limit it's ability to get to 100% measurement range of the ADC, if the chip is powered with ground and +5vdc. And if powered with a higher Vcc then there is always a risk of overvolting the input pin?

Lefty

CrossRoads

LM358 was an example. I think it'd be fine with some tweaking of the offset and checking for non-distortion of the output.
Or find a wider output single supply op-amp.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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