Hello, I'm trying to amplify an audio signal using an LM324N in a non-inverting configuration. I'm not trying to build an audio amplifier to drive speakers, I just need to amplify it a bit for another project.
The problem is when the opamp is on a signal supply (12V to GND) and the input signal goes below 0V the opamp saturates positively (Figure 1) when I expect it to saturate negatively. However when I use a bipolar supply (12V to -12V) it works as anticipated. In my application I would only be able to use the signal supply. I checked the datasheet and the minimum input CMRR is 0V so isn't that an indication that it should be able to swing all the way to the negative rail? I'm not sure what's the issue with the single supply vs the bipolar supply and saturation.
How can I fix this circuit to work on a single supply (Figure 1) and saturate negatively when the input signal goes negative?
EDIT 1: Added biasing and AC coupling on input and output(figure 3)
EDIT 2: Connected R4 to Vcc/2 (Figure 4)
EDIT 3: Changed AC coupling caps to 100uF