Thursday 28 February 2013

Prototype Version 0.5b

As I recover from my accident I have been doing a little work progressing the prototype hardware to the next version. This version incorporates a few user suggestions, improves the look, and is slightly easier for me to make.

A summary of key changes from version 0.4b:
  • A new case based on the Dangerous Prototypes Sick of Beige DP5031. This is slightly smaller than a tic-tac box in length and width, but it is a little thicker. The extra $1.50 compared to a box of tic-tacs is worth it, considering that final assembly is easier, it is noticeably smaller, and it looks way cooler. A few people have mentioned that they are concerned that the sides are exposed. I am not. If you are, just put the whole thing in a small ziploc bag or 40mm heatshrink. 
  • I have switched from mini USB to micro USB for the charging point. This is the same as pretty much every Android device and it should be easier for most people. The connector is a little more flimsy, but I have been generous with the amount of solder I use to keep it on. 
  • I have changed the battery type to a 35x30x6mm 600mAh LiPo. This smaller capacity is a compromise based on what was available (I could not get more of the old one) and what would fix in the new case. The battery life is now around 12 hours, which is still way more than is really needed. 
  • The new PCB layout is a little neater. All of the LED's are lined up on the side. The RN42 antenna does not hang over the edge of PCB. Apart from looking cooler, this results in the device being easier to make.
  • I have changed a few of the tantalum capacitors to ceramics. This has reduced the electrical noise by about 10%.
I have only made a small run of prototype version 0.5b. There are a few available through the order site. See the image below:

Prototype version 0.6b is in the works. It will be very similar to version 0.5b, but with a few more PCB layout tweaks to make it even easier to manufacture. I intend to release the complete design files for that version under some sort of permissive free licence (including PCB gerbers, schematic, and PIC24F code).