I'm trying to prototype a hobby project on a breadbaord.
I'm using an electret microphone + opamp to feed MCU ADC with audio signal. When I'm using a regulated power supply I get good signal with relatively low noise.
Now I wanted to power it with battery using a step up boost converter - but got a serious noise problem on the amplified signal.
Since it's a hobby project I don't have the equipment (scope) to find the exact characteristis of this noise, I only know it's bad enough to completely ruin my audio input, and that it comes from the boost converter since I don't get it when I use regulated power supply or when connecting the circuit directly to batteries.
Tried to add decoupling caps, but it didn't help much. I even tried adding another low dropout regulator (s81230ag) before the opamp and adc analog power but the noise is still there.
How would you recommend to proceed?
- Is there a simple way (small number of components, on a breadboard) to filter this noise with the existing components this and this?
- Should I try a differnt boost converter, perhaps with switching frequence high enough so it could be filtered by the mic amplified circuit?
- Pehaps I should use a differnt amplifying circuit for the mic which is less susceptible to power supply noise?