I'm currently stuck on trying to figure out how to cram all of the electronics on this board together with means for installing 4xAA NiMH batteries. It's like the HOODMICRO all over again. This one is going to be designed around the dimensions of a standard Altoids tin. Altoids tins are pretty close to the form factor desired and they are very easy to obtain. If it worked for Lady Ada, it should be good enough for us too, right?
A set of 4xAA batteries fits nicely inside the Altoids tin. If you lay down a standard thickness PCB with DB25F connector attached, the lid closes perfectly. But there is no room left to spare. There is definitely not enough space for a plastic battery holder. Anything that makes the PCB slightly thicker makes the lid fail to close. We're going to have to try keeping a flat space on the bottom of the PCB, one big enough for the batteries to rest in. We're also going to need some springs/tabs for connecting to the battery terminals. I think this might be possible to do with existing parts available from Digikey/Mouser, but I haven't gotten all of the details worked out.
The other alternative is to use smaller AAA batteries. I don't really want to go that route though. AA batteries pack far more power in each cell and don't cost much more than AAA batteries. A single AAA NiMH battery holds up to 850mAh of power, while AA NiMH batteries hold up to 2600mAh and only cost $0.45 extra.
Moved the Helix MP3 Decoder link to the FAQ. MP3 is not the main focus of TRAXMOD.