I'm trying to flash an LED when an AC current is over 4 amps. To do this, I'm using a current sense resistor of 0.01 ohms. That gives a threshold of 40mV. But I can't figure out how to use this voltage to trigger the DC LED flashing circuit. I thought of an optoisolator, but 40mV isn't enough to run it. Any other ideas on how I can "connect" the AC to the DC LED circuit?