Low dc current with USB 6009

[tripper]

Hi all,

i am using USB6009 to measure low dc current(0 - 2A) .My question is which is better solution; Shunt,feedback shunt, cureent sensor or hall effect sensor.

Right now i am using 30m Resistor and getting good results with 20mA error.I need 1 mA resolution and just thinking if there is a room for imrovement.

Thanks

[johnsold]

tripper,

Do the math: 0.030 ohms * 0.001 A = 30 microvolts. USB-6009 resoltuion on +/-1 V scale is 244 microvolts.  You will need an amplifier or ither typs of sensor/transducer.

Lynn

[SnowMule]

Shunt resistor of a couple of ohms (if loading isn't an issue) with a current-sense amplifier and you should be set.

V=IR, and read over the datasheet for amplifiers... I try to target 0-5V or 0-10V depending on what voltages I'm running in the equipment (if I only have 5V, i'm going to configure it for 5V full-scale).

Hall-effect sensors are good for AC, I use those for looking at current coming into the equipment or as a check to see if other devices (heaters, fans, etc) are turned on.