I’m having some issues trying to process sound on my ESP8266 NodeMCU using a standard electret microphone (Electret Microphone Amplifier - MAX4466 with Adjustable Gain : ID 1063 : $6.95 : Adafruit Industries, Unique & fun DIY electronics and kits). The circuit is as simple as possible - 5V wall transformer connected to the wall powers the microphone, with the output directly into the analog A0 pin. Code is simply reading Serial.println(analogRead(A0)). This outputs the attached noisy signal.
Not only is the signal noisy, but it picks up almost no other sound. Only when banging the mic on the desk or tapping it directly do I see any sort of response. I’ve adjusted the potentiometer in all directions with barely any effect. I’ve tried a total of 3 identical mics and all are like this. I’ve tried multiple ESP boards, so it’s that.
Are these mics just terrible? Am I doing something wrong? Do I need some caps to reduce noise, or resistors somewhere? Most diagrams I’ve seen don’t include these. Any advice is appreciated, thank you!