Current sensor amplifier and over current switch project is based on ACS714-30A current sensor and LM358 Op-amp, ½ of LM358 op-amp used as an amplifier for low voltage and 2nd 1/2 LM358 op-amp used as comparator which provides over current TTL output, trimmer potentiometer provided to set the over current limit. ACS714 sensor measures the current up to +/-30Amps, final output of the amplifier is 235mV/1A, and normally over current output is High-TTL, its goes low once the current over shoot than a set point. Circuit requires 5V DC and 40mA, Onboard LED indicates the power. Resistor divider R1, R3 provides bus voltage output for micro-controller interface to measure the bus voltage, choose appropriate value for R3, R1 as per your application and bus voltage, it’s should be less than 5V DC.
Current Sensor Amplifier & Over Current Switch – [Link]