Source for current-sense resistors?
Charles Linquist email (remove spam text)
Really low-ohm resistors are difficult to do, because even the solder
connections to the part change the resistance. Individual calibration of
each sensor becomes mandatory if you want any decent accuracy.
Have you thought of using the Allegro hall-effect sensors (like the
ACS750SCA-100) instead? I use them all the time with great results.
I use one op-amp to move the normal Vcc/2 offset to near gnd, and
amplify the output by about 1.8. I then take that output and feed it
into my PICs A/D. I have a "calibrate" button that takes the A/D
reading at zero current and stores that value in EEPROM. All subsequent
readings subtract out that value.
No pots, no adjustments and 2% accuracy to 100A.
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See also: massmind.org/techref/power.htm?key=current