SparkFun Current Sensor Breakout - ACS723

Spark Fun delivered on time with no problems. Good price. The current sensors work very well with low noise. I am using it to measure current through a Stepper Motor winding. Works great!

I bought this intending to use it for a custom linear power supply I've built. I was planning to read voltage from it using an arduino analogRead() as proxy for DC current flowing through it, as it was designed.The product manual on the ACS723 indicates it has 400 mV/A output, so does this product. Using the circuit they describe here: file:///Users/deansanders/Downloads/ACS723-Datasheet%20(2).pdf I tested this module.With highly accurate volt-ohm meters I wasn't able to get a >4mV delta with ~106 mA flowing through it (i.e. 5V across a 47 ohm resistor). If the output scales linearly with amperage it should be 40mV not 4mV. This is far to low of resolution for an arduino to effectively read current... I wanted 10 mA resolution, not worse than 200 mA.I thought it might just be a badly machined part, so I returned it. Got another, tested it, got the exact same result. They are NOT sensitive for low amperage DC applications, which again is not mentioned in the datasheet. If your looking for an accurately scaling low amperage I.C. go for something else. I just ended up a using a cheapo current meter I have laying around, it works way better than this.

the potentiometer is super hard to reach