This is my first Instructable, so be kind! Right, here goes...
I was trying to sleep one night, but couldn't. I wanted to listen to music, but fnd headphones uncomfortable at night, so I decided I needed a small speaker, and the Hi-Fi in my room would be too loud; so I gathered together some stuff I had lying around, and after about 30 mins, I had a mini MP3 speaker!
It's not very loud, as it's powered purely from the headphone jack, meaning that the tiniest amount of soldering is required, and you don't need to make a PCB.
Speaker (I used an 8 ohm, 0.5 watt one pulled from an old walkie talkie;
3.5mm Headphone Jack;
3.5mm Male to Male Cable;
Step 1: Making the Shell
First, mark out your panels on your cardboard. the sizes I used are:
12x10cm for the front and back panels,
4.5x10cm for the two side panels,
4.5x12cm for the top and bottom panels.
After you've marked the panels out, use scissors to cut them.
Measure the diameter of your speaker. Mine was 2 inches (5cm). On one of the 12x10 panels, draw a circle of a slightly smaller (couple of mm) diameter than your speaker, and cut it out using whatever you feel works best, I just used scissors.
Step 2: The Wiring
In this step, all the wiring/soldering takes place.
First, get your headphone jack, and solder one leg to one wire from your speaker, and the other leg to the other wire on the speaker. Then plug one end of the 3.5mm male to male cable into the jack, and the other end into your MP3/iPod and play some music just to check it all works.
If all is working, mount the speaker into the hole made in the front panel in the previous step, and use hot glue/blu tack/tape to hold it in place. Then, make a hole in one panel (I used the top) of about 4mm, and use tape to mount the headphone jack.
Step 3: Sticking the Panels Together
Now is time to stick all the panels together. Simply add several bits of tape to the panel with your speaker in (on the opposite side to the wires), and add on the other panels in a net. Then it's a simple matter of sticking them together so that they form a box shape.
After that, plug in your music player and listen to your music!
Hope I taught you something in this Instructable. :)