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Topic: analogreference and resolution question (STILL NEED HELP) (Read 1 time) previous topic - next topic

jcarabet


EmilyJane

If you don't know how to hook up an op-amp, then you need to start a little closer to ground zero. I'd find a tutorial and learn a little.

In case you didn't get what Grumpy_Mike is trying to tell you: The minimum allowable Vref is 1.0 volts. You can't use 100 mV. You'd be better off using the internal reference, Vint, since you don't gain anything by supplying your own.

Magician

May be you can change shunt value, to get higher voltage?

EmilyJane

Normally shunt resistances are chosen so as to not effect the circuit they are measuring. The OP possibly doesn't have the option of raising the shunt resistance enough to help. If he doesn't want to amplify the signal, an alternative would be to use an external ADC with a large enough dynamic range to accurately handle the 0-50 mV signal and read it into the Arduino for further processing and display. A 24-bit ADC would give you about 0.1 microvolt resolution with a 1 volt reference. Ought to do the trick.

Magician

I can't agree with your logic. If OP have no knowledge to build simple OPA amplifier, how he/she could follow your advise to implement external 24-bit ADC? It doesn't make any sense.
I just assume, that OP probably doesn't work on something high power or high precision, when increasing shunt resistance wouldn't be desirable. The same time it is the easiest way for someone w/o electronics background. If shunt resistor "build-in" IC, there is always option to add external one.

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