I combined my Arduino with a text to speech module and a simple 12W audio amplifier. However, now whenever I let the Arduino dim th ebacklight of the LCD I get this anoying continuesly high peeping noise through the speaker.
My grounds all come from a central point (my +5V do not) and I already tried shielding each and ever cable having to do with audio. No success here. I did figure out the potentiometer I have put in between the amplifier and the sound input does not affect the peeping volume.
I guess the noise is generated by the PWModulation of the back light of the LCD being dimmed?? Am I correct?
Anybody have any idea what I can do next to try to stop this beeping?
I can remove the beeping by always setting the backlight either completely on or off. But that's not what I want.