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measuring current — Parallax Forums

measuring current

edlikestoboogieedlikestoboogie Posts: 71
edited 2007-12-06 01:00 in BASIC Stamp
I need a way to accurately measure current from a solar panel cell ( the current will probably be between 0 to 200mA) and I need it down to a .1 mA accuracy.· I'm sure this has been covered a million times, I was just wondering if someone could post me a link real quick that I can read up on.· Thanks guys.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2007-12-06 01:00
    Current is usually measured by putting a small resistor in series with the current and measuring the voltage across the resistor. Typically, you'd use an op-amp to amplify the small voltage involved to something closer to a 0 to 5V range which could be the input to an analog to digital converter. You'd need a 12 bit ADC to get the resolution you want (0.1mA over a 0 to 200mA range). Whether you'd get the accuracy you want would depend on the op-amp, the resistor, the reference voltage for the ADC (often supplied internally) and the stability of the power supply for the op-amp and ADC.

    Start with the "Basic Analog to Digital" tutorial from the Stamps in Class section of Parallax's website. Also look at www.emesystems.com.
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