New to Arduino.. and am wantign to replicate an effect I saw on a little McDonalds Avatar toy.
where the PCb has some sort of 'flat' sensor..that either using audio or vibration and transmits it back to the PCB >> to light an LED in 'time' with the audio/vibration around it.. (I believe it also uses PWM as the brightness varies on loudness)
The flat disc connected to the board is a piezo sensor, which turns knocks into a small voltage that can then be measured. They are commonly used in cheap electronic drum kits etc
The black circle on the PCB is actually a chip, which is created on the board itself ( a very cheap way of mass producing these items ).
The method you suggest of reading the value from the ADC in a loop, and setting the brightness of the LED accordingly should work.
It's not the most accurate way of doing things, but for a simple device it should work just fine.