The Sonik Sound Dock was just a little thing I threw together in my spare time. Seeing iPod sound docks costing upwards of 20 bucks spurred my need for portable, sharable sound. It's great for carrying to smaller parties/get togethers, or just when you're studying in a different room from your computer.

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I found this little speaker sitting at Goodwill for 3 bucks. Originally meant to hook up to a surround system, this is just a speaker and a box. No power, amplifier, nothing. Just hooking this up to an iPod will produce sound, but it'll be incredibly quiet. Like "put your ear to the speaker to listen to it" quiet. closed
So I decided to build a small amplifier and house it inside the speaker box itself, to keep everything compact and portable. closed
The amplifier is the LM4950, lovingly known as "My First Chip Amp". It is an amazingly versitile chip, and can be driven off a simple DC input voltage. closed
What this means is, you hook up the chip to power, audio input, and a speaker, and you're ready to go. The only other components are a capacitor and resistor combo to remove unwanted noise, and a few more resistors to set the gain and bridge the load. closed
The schematic can be found in the LM4950 datasheet. http://www.national.com/mpf/LM/LM4950.html The only thing I modified was changing Rina, Rinb and Rfb to 4.7Kohms, and Rfa to 47Kohms. This sets the gain to 10x, so the chip can drive the speaker a little louder. Making a circuit board for this would just increase the complexity without any real benefit, so I just soldered the oomponents up on protoboard. closed
I hacked off an old pair of headphone to get a 3.5mm stereo headphone jack that could be plugged into anything. Also hooked up a pretty generic DC input to the back, that fits 12VDC power adapters that can be found in anyone's house. No switches or buttons, it just turns on when you plug in power, which can be anything from 6-12V, as I tested. You can make a little battery pack for portable applications too. closed