Hello @here,
A few months ago, I built an automatic transfer switch using solid-state relays to test their performance. The system had been working well until recently when I stopped receiving readings for both my mains voltage and current measurements.

Initially, I suspected that the ADC pin might be damaged. To verify this, I applied 3.3V directly to the ADC pin and displayed the readings on the LCD. I was able to get 4095, confirming that the ADC pin is still functional.

Next, I tested the LM324, which I’m using as a differential amplifier to measure AC signals. The IC appears to be working fine as well.

At this point, I’m unsure what could be causing the issue. Has anyone here worked with AC voltage sensing using op-amps? If so, have you encountered a similar problem before? Any insights would be greatly appreciated!