Well, I have a couple of projects and I would like to make this next one open source!
As you may know, in my day job I do a lot of programming and stuff with micro-controllers. Well, I have designed an ultra small portable amplifier with digital volume control. This one is designed to be powered by a single 3.7v Li-Ion and charged from a USB port using a MicroUSB or MiniUSB connection. It will be offered in two small programmable packages using a DS1803 for volume and an MSP430 micro-controller for analog to digital control conversion. The used potentiometer is going to be a cheapo linear slider for maximum thin-ness and cheap! There will be a 3.7v to 5V step-up converter, just to give better voltage swing. I will also include a piece of code and a version eventually for those of you who may want to use an Arduino because coding is easier to understand and you can make a DIY version in DIP.
Just know, you can buy an MSP430 for a lot cheaper, lower power, does not require an external crystal, built in pull up/down, and a full programmer will only be $4 shipped. It is however, much harder to program and not as widely available.
The board I am talking about will use all SMD parts for thinness and size considerations. Right now, I am trying to make it so that there will be absolutely no capacitors/inductors in the signal path and it works in theory.
Will get my PCB’s made by FusionPCB ($20 + shipping for 10 PCB’s – yay!). When it is ready, let me know if you want a PCB and I will gladly sell it to you at cost.