ACS712 30A Hall Effect Current Sensor Module

The ACS712 measures current without breaking the circuit to insert a shunt resistor: a Hall-effect sensor inside the chip reads the magnetic field generated by current flowing through an internal copper conduction path, and converts that into a proportional analog voltage centred at half the supply voltage. On this 30A module, that means roughly 2.5V output at zero current, moving up or down as current flows in either direction - it measures AC and DC current equally well.

Sensitivity is 100mV per amp, which an Arduino's analog input reads directly with basic math to convert the voltage back into a current value, and the fast 5 microsecond response time is enough to catch short current spikes rather than only steady-state readings. A single 5V supply is all it needs to operate.

Common uses are battery current monitoring, power consumption logging for solar or automation projects, and overcurrent protection circuits where a microcontroller needs to know how much current is actually flowing rather than just whether power is on.