I am working on a project that involves a simple device that plays a 5 second audio track (consisting of a man speaking) when a switch is turned on. I am using an Atmega328 chip with an Arduino bootloader to read a WAV file from an SD card and stream that audio data as a PWM signal to a LM386 audio amplifier set for 200 gain and the whole thing powered by 5x1.5V batteries . The application works however the outputted volume is a little low for the purpose of the application (this device will be placed in a open outside pedestrian area and is supposed to be clearly audible to a person sitting right next to it). I have added more batteries all the way up to a total of 12 v and increased the volume a bit more but it is not quite satisfactory and i would also want to avoid using more than 5 or six batteries on it.
I was thinking i can use a Class D amplifier since i understand that they are great for low power portable applications. Since i see that these amplifiers take analog signals as inputs my question is how can i interface the pwm audio signal that i have with it? Do i use a simple low pass filter, do i need a DAC or is there a simpler way to do this. Can the volume be increased noticeably this way or is it strictly dependent on how much juice i put through it in the end.
Thank you in advance for your response.
I was thinking i can use a Class D amplifier since i understand that they are great for low power portable applications. Since i see that these amplifiers take analog signals as inputs my question is how can i interface the pwm audio signal that i have with it? Do i use a simple low pass filter, do i need a DAC or is there a simpler way to do this. Can the volume be increased noticeably this way or is it strictly dependent on how much juice i put through it in the end.
Thank you in advance for your response.