SparkFun Current Sensor Breakout - ACS723

The SparkFun Current Sensor Breakout is a high accuracy board that utilizes the ACS723 for moderate AC and DC current sensing applications. This sensor is not recommended for current sensing lower than 10's of milliamps. The SparkFun Current Sensor Breakout measures both DC and AC currents all the way up to 5A, has full electrical isolation of measured and sensed circuits, and has a base sensitivity of 400mV/A. Although the analog output is adjustable to 80kHz. The ACS723 sensor uses a Hall effect sensor to output a voltage relative to the current flowing through the IP+ and IP- pins on the board. The advantage of using a Hall effect sensor, specifically, is that the circuit being sensed and the circuit reading the sensor are electrically isolated meaning that, although your compatible with Arduino is running on 5V, the sensed circuit can be operating at higher DC or AC voltages! You should keep in mind how much power your resistors can handle though! If not, they'll end up a bit toasty... With 5V and 100mA, the power would be 500mW or 1/2W. The small resistors in the kit above can only handle 250mW or 1/4W at most. But, wait! A resourceful engineer knows you can still use the 1/4W resistors, you just need to split the power dissipation.