I tried to built a small pre-amp to use an electret mic as an audio input sensor for a project, but I am not getting the readings that I want from it. Full disclosure, I put the schematic together about a year ago, and only just recently got the PCB made. I thought it would be OK (everything else is working fine), but I didn’t do my due diligence on checking it out
My project uses a 3.3V Arduino core, so I put together a really simple pre-amp based on a 2n2222 to amplify the electret mic signal for analog reading. Trouble is, every reading I get is over 1000 (returned by analogRead())! I now know that I maybe should have gone the extra step and used an op-amp, but I’m just curious about why this didn’t work.
Its been a couple years since I’ve had any analog circuitry course work, so I don’t quite know what is wrong with the schematic attached. Can someone give me some insight about why I am getting nearly maxed out readings at all times with this?