Now before you even read any further. These are not really loud. Just so you know. They are great for sitting at your desk, but you would not want to have them as music for a party or anything. Now you could make a larger more powerful amp, but I didn't. Just FYI.
Here is a video of it playing with the MP3 player I made.
Step 1: Getting everything you wil need....
Then you will need the following:
One NES game of your choice. I only used Rush N Attack because it was the cheapest one I could find.
Two small speakers that will fit into an NES game. 1 Watt 8 ohm. ((0.5 watt are better.))**
Two LM386N ICs
Four 100uF caps
Two 100k resistors
Two 1k pot resistors
Two rectifier diodes
One ON/OFF switch ((Just get the smallest one you can.
6-12 votls worth of batteries. I used watch batteries ((6 volts worth)) due to the limited space. You could wire up a 9 volt and just have it on the outside of the game case. But it would look kinda weird. LOL
** I got these speakers out of an old Dell laptop I had sitting around.