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measuring mv and ma with a BSII or sx28 — Parallax Forums

measuring mv and ma with a BSII or sx28

CenlasoftCenlasoft Posts: 265
edited 2008-11-09 03:39 in General Discussion
Hello,
I am trying to make a resistivity meter. I need to measure millivolts and milliamps. Does anyone have any thoughts? I have a 0831 ADC for possibly measuring mv. I was thinking of using a capacitor and resistor (RCTime) to measure current (ma). Any help would be appreciated.
Thanks,
Curtis

Comments

  • CHIPKENCHIPKEN Posts: 45
    edited 2008-11-09 02:14
    Use a DS2760 or buy the Parallax thermocouple sensor. You can detect +-64 mv.

    Chuck
  • VelocitVelocit Posts: 119
    edited 2008-11-09 03:26
    Make a sigma-delta ADC with an RC network and measure the voltage across a resistor (1% tolerance) using SX/B's RCTIME command. Now that you know the voltage and resistance of the system, just use Ohm's law to deduce the amperage.

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    -Paul
  • ercoerco Posts: 20,260
    edited 2008-11-09 03:39
    Or, just buy a cheap CEN-DYNE multimeter from Harbor Freight for $3.99 or less. I have got to admit, they're cheap and quite useful. I have 3 that I keep in different places, and although I have pricier meters, I reach for the cheap ones first, and rarely use the "good ones".

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    ·"If you build it, they will come."
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