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I have a piece of tech that uses somewhere between 50-200mA, and I want to continuously measure the current used. To this end I have found this:

Sparkfun ACS712 breakout board

Allegro ACS712 chip datasheet

I've hooked up the supply voltage to an arduino 5V and the GND to the corresponding GND on the arduino. The reason I've chosen to use my Arduino for the supply is that it gives a stable 5V all the time. I've connected both of the IP+ channels to each other and the two IP- channels together aswell. After this i connected it to my unit like this:

[12V PWR 1A]+ --> [[IP+]CIRCUIT[IP-]] --> [+[The piece of hardware I want to measure]-] -->[GND]

I have to set Vref on the board when the thing is disconnected by measuring the voltage over V0 and GND and turning the Vref until it says 0V. But then what? What do i do next?

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  • \$\begingroup\$ 66 to 185 mV/A output sensitivity if you're using 50ma, it could be a very small voltage close to 0. \$\endgroup\$ – kenny Jan 24 '13 at 13:15
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According to the Sparkfun web page:

The ACS712 Low Current Sensor Breakout outputs an analog voltage that varies linearly with sensed current. To calibrate, first set the output offset to the desired level (with zero current on the sense lines, read output with a DVM). Then with a known current input (a 100mA limited supply works well for this), set the output deflection with the gain pot. Sensitivity is then calculated as (Vref - Vdeflect)/(current input).

You've done the first part, now do the second part.

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