I have a project where a sensor will provide me with a variable current from 0 to about 250uA. What would be the easiest way to measure it, as precisely as possible, with an Arduino?
I know about shunt resistors, but the current here is so tiny that perhaps using an additional external IC would help. I know there are "ammeter" chips around, but I don't know what to look for exactly, and most of the things I've come across are rated way higher. Perhaps I should just use an OpAmp?
Any kind of suggestion will be greatly appreciated, thanks
You need to specify this clearer. The simplest way for precise measurement with Arduino is to buy a precision meter with Arduino compatible interface
"as precisely as possible" is very fuzzy. How much precision is needed? +/- 1uA, +/-1nA, +/-1pA, more precision? How much resistance in the measurement appartus is admissible? Are you measuring AC and/or DC? How many samples per second do you need? Or would it be admissible to measure at very low sample rates (e.g. 1 sample per day)? What is the admissible price tag?
Udo, thanks for pointing out the lack of info about my requirements. I wrote the post in a rush, but anyway:
A separate meter is not an option, as my aim is to get everything packed inside a single box. The circuit I'm working on is supposed to have a 250uA FSD analog meter panel, but instead of that, I want the input to go to an Arduino that will eventually display the value on an LCD. Obviously I'll not use a "real" arduino in the final product, but only a properly programmed ATmega.
+/-1uA would be great. Even 2.5uA would do, giving me a scale of 0-100.
I'm measuring DC currents
It has to be at least 1 sample per second
The total cost should be limited, let's say a maximum of $20 for the measuring circuit
Hopefully, I made myself a bit more clear now
Thanks,
S.
P.S.: OpAmps usually amplify voltages... is there a way to directly use them to amplify a current, without first converting the current into a voltage?
