Hello everyone,
I need to design a circuit to sense the output voltage and output current of an amp, the power is around 400W 4 ohm.
For the output voltage, I try to divide the voltage by 10 simply by potential divider and use peak detector to provide the information to the ADC
For the output current, I try to add a 0.02 ohm sense resistor along the output and get the voltage before and after the sense resistor. Divide both voltage by 10 and use op-amp subtractor to get the difference, then peak detector again to provide information to the ADC
However, problem here. For 0.02 ohm, I only got 0.2V difference even at full power. If divide by 10, difference will become 0.02V only. I can't distinguish the difference from the ADC for smaller output. Any suggestion to solve this?