simple and superb.
Step 1: Needed Components
speakers 4 inch 3 watt
batteries 4v 1ah -2 or 4
capacitors , ic, resistors are specified in circuit.
soldering iron and lead
other: Sun board
Step 2: Circuit Work
Step 3: Silver Jumper Wire to Every Component
solder the 5v input of the mp3 module to the output of the regulator circuit.
and audio output of the mp3 module to the jumper wire and connect thou the the amplifier circuit.
Step 4: Sun Board Cutting
also cut for the speaker .
when I took this photo the speaker was already fixed.
after cutting fix them in place hot glue and screw them.
then attach the Sun board to the lid of the plastic box.
Step 5: Connecting
Step 6: Charging
but if you want to use 12 volts adapter, you have to add the above circuit.