I am curious as to the nature/relationship between PWM and audio output.
I have played around with several projects/circuits.. and have tried to do simple PWM on ANY PWM enabled pins..and can always 'hear' it through the speaker over the music..
I have played with:
Arduino & Waveshield.. trying to PWM leds..and can 'hear' the PWM through the speaker..matching the led fade..etc
PWM output (using the SimpleSDAudio lib).. and when I also try to PWM a few leds while playing a quick audio clip.. you can hear the PWM fade as noise over the clip/speaker..
Tone output using a small amp to boot the volume a bit... fade an array of leds through a transistor..(powered from separate pack, and GNDS tied together..etc)....and again, you can HEAR the pwm/fade.. when it stops the buzz/noise/static over the clip stops as well..
so Im trying to get a base/foundation of why this stuff happens..
(hopefully not a bunch of equations and links to filters/calculators...etc, looking for a more general understanding to build from) why Im posting hte gneral section.. mot audio.. to keep in the beginner arena.
obviously some kind of noise due to the PWM'ing...
but how does one go about fixing this?
is this where isolation/opto-isolators come in? (which is all new to me still)
I have a project that i want to get back to soon..
more or less Arduino + Adafruit Waveshield.. but I need to make a custom PCB for some MAX7221 chips to contol a MATRIX of leds (2 x MAX chips, 60 leds on each chip).. so a voltage regulator, iSet resistor for the current..... some pads for the battery pack and Arduino 'control' line/pin...etc..
so I wanted to talk it out in hopes of learning what I can do to ensure better audio output..