Hi everyone,
I found a circuit which convert PWM into audio signal.
First they used 2 cascade low pass filter and high pass filter, then LM386 audio amplifier with RC.
Could anyone please explain in more detail about the circuit ?
As I know, the first bandpass filter is used to attenuate the PWM.
I have tried to play the duty cycle from digital 0x00 to 0xFF.
The output from these band pass (before Opamp LM386) is shown.
The value is only about mV, although the PWM is 0-3.3V
Thanks for your help.
It will be very appreciated.