How would one measure many (20-100) small voltages in the 0-80mV range with an Arduino? I will need to amplify them and put them into the ADC. But i also need to switch between them. I want to measure the lot in about 1 sec if possible, so an electric solution with no moving parts would be best.

What parts can be used to switch between the different measurement ports?

Additional Info: I want to measure Temperatures (in the range of 0-100 degrees) using Thermocouples (K-Type) for an Experiment I am conducting. I then want to plot that data on the PC. The arduino has an 11-bit resolution; meaning that in theory when I amplify those few mV from the Thermocouples i should (in theory) be able to get about 1 degree of accuracy (i am fine with even around 5 degrees though). I can think of multiplexers being able to do the job, however I have no Idea where to look for them.

  • How accurate should it be? The most basic arduino uno can measure that with 2mV accuracy. Can you tell what your project is? Do you want to add more inputs in the future? Is it battery powered? What are you going to do with all that data? send it to a computer? Please add the extra information to your question. Can you solder electronics yourself or design a pcb or do you prefer modules with (soldered) wires. Start here: gammon.com.au/forum/?id=11976 – Jot Mar 19 '19 at 21:03
  • I have no issues with soldering. Can a multiplexer forward such small voltages without significant noise? Or do I have to amplify each single singal before leading it into the multiplexer? – RIJIK Mar 19 '19 at 21:11
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    To measure with a thermocouple, the wires of the thermocouple should be connected close to a special chip: adafruit.com/product/269 I hope that someone else has a good idea, but with thermocouples and 1 degree accuracy this might be impossible. What object(s) do you want to measure? can you use a thermal camera? Please change the title, this is about measuring multiple temperatures with thermocouples (that is not the same as measuring voltages). – Jot Mar 19 '19 at 21:24
  • I actually already have one of these. I just don't want to buy that 50 times. Hence the switching. The chip works well enough. The material is almost closed off to reduce some dynamic effects. A Camera will require too much space that is why I would prefer Thermocouples. – RIJIK Mar 19 '19 at 21:40
  • you will get more precision/accuracy by switching amplified lines, but it's hard to say how much better that would be, if it's actually needed, or if you can trim out/compensate for artifacts caused by switching pre-amplification. I would try two n-channel logic-level mosfets that switch two inputs (D) to the amp (S) and see how well that works, if at all. – dandavis Mar 19 '19 at 21:50

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