A year ago I’ve got the idea to build a simple mp3 player for my daughter. Now - more than a year later it is finally finished.
The player supports 144 songs which are saved on an internal sd card. You select the songs by choosing an “album” and then pressing one of the twelve buttons. Power is provided by an internal powerbank which can be charged via the usb connection on the back.
The first plan was to use punched cards to select the music album to play, The each card would contain 10 songs, and there would be multiple cards to insert into the player. The player was not usable and I’ve tried again with a much simplified Idea. Just using a rotary selection button to select the „Album“, and a LED to show the selection. Increasing the number of albums to 12 also allows you now to display it like a clock. And finished it is :-)
The player uses an Arduino for controlling the song selection. The mp3 playback is handled by a self containing mp3 module I found on the internet. To have enough outputs the LEDs are connected via two shift registers. To not empty the battery when nothing is playing (this was a problem on the first version). I’ve also included a electrical switch to be able to shutdown the player after a given time if it is not in playback.
The second player
After building the first player I build a second one where I simplified a lot of the construction. Main changes are that I use an Arduino Mini instead of an Arduino Uno, which simplified the pcb soldering a lot. The LEDs are still driven by a seperate LED driver board, containing two shift registers.