The only one I have is a 1 ohm that measures 1.6 ohms (assuming that measurement from the same Fluke meter is good).
For now I'll just take the measurements at face value from the meter as I've always done. I did a test by saying if each DMM causes a drop that I fear may interfere with my current measurement, let me see if I put 2 DMMs in series do I get an increased error.
I saw about a 2% drop in the current reading of the fluke when I added another cheap current meter in series (each meter on its own caused the 0.4v drop) so it looks like my best bet for now is just take the readings and not worry about how it works.
The meters wouldn't be very useful if they didn't give good readings at low scale so I have to hope I'm just thinking about it too much.
Hi again,
Oh i see, ok, well you know you can get resistors at quite a few
places that sell electronic parts, or online in several places.
Another idea is to use linear interpolation...
With this, if you measure 220ma with 2.9v then you will measure
3.3/2.9*220 or about 250ma if the voltage was really 3.3v as it
normally has. This is a good approximation if the circuit load
behaves as a linear load, and probably not too bad even if it doesnt,
unless of course it draws constant power in which case it will draw
less than 220ma. If you put two meters in series and the current
drops even lower than the 250ma estimate probably isnt too far off.
There's also a 'compensated shunt' which maintains the same voltage,
but you probably dont need that much accuracy anyway.
So to recap:
If you measure 220ma at 2.9v when it should be 3.3v then the corrected
current value is probably close to 250ma.