I’m also working on a new circuit tentatively called “Mood Spark” which acts kind of like the mood-rings of old, it’s got a temperature sensor and RGB LEDs and will change color as the temperature changes. No idea if it will work very well, but it should be fun to play around with!

UPDATE: I’ve made a tech details page for Sound Spark, you can go download the code, etc. Enjoy!

Heart Spark is almost ready to go on sale. I have received the first lot of boards from China, assembled and tested the first one (works!), so sometime this week you can expect to see a limited number for sale here. Currently I am assembling them myself, it takes about 30 minutes of delicate surface mount soldering per board, plus extra time for programming, testing and the all important attachment of the jewelry bits, of course .

I thought I’d share a little bit about the process of making the kits. It was the first time I personally had made kits and it was a very educational experience. At a very high level, it goes like this:

1. Figure out how many kits you plan to produce
2. Count the parts you have on hand and do the math to figure out how many parts to order
3. Track the parts as they arrive to make sure they’re correct
4. Do the part manufacturing – the North Paw has two custom parts, the armature and the enclosure, each with its own manufacturing process, and many of the other parts required processing
5. Pack the kits – ours have three nested levels: the delicate components which we put on static resistant foam, the rest of the components in the electronics bag, and everything else

Pretty straightforward, right? Well, at any stage in that process, there is an enormous amount of detail, and occasional snags. It’s pretty clear how getting the armatures sewn up could be highly detailed, I’m sure. Well it turns out that there’s complexity even in ordering parts. In many cases we could order parts from a number of different suppliers, with slightly different prices and different shipping times and costs. Bundling is necessary. Minimax for ALL the parts, though, fails when you run into someplace that is out of stock but doesn’t say that up front… especially if you have already placed orders with other vendors.

Must flash the code onto all the ATmega controller chips. We have a jig for doing this. For other parts, there’s a fair amount of chopping up to do! The velcro, the cabling, the heat shrink tubing, even the static resistant foam all come in larger pieces than required for the kit. This is really easy to do, but takes some time. When it’s time to pack the kits up, a bunch of little Dixie cups are great for sorting, and you can just pour the parts from the cup into the bag. Remember to print stickers to close the bags up with! Did a business card get into each one?

The one snag that is at all interesting is this. The acrylic enclosure is cut to fit precisely over the slots on the board. In this batch of boards, the inner corners were rounded, not square, so the acrylic didn’t quite fit all the way. I ended up grinding down these inside corners rather than trying to redesign the enclosure, so they should all fit perfectly again – if you find that yours doesn’t, it’s easy to use a tiny grinding wheel or even a small file to trim it a little farther.