What I want to do
I'm trying to come up with a single-board prototype for Public Lab's Thermal Flashlight project. I'm trying to build on the great design ideas put forth in recent research notes -- the idea of adding a thermal flashlight shield to a Visuallight board, and the proposal to mash up the Sparkfun IR breakout board with a 32u4 processorand an RGB Led. I'm still rather new to designing boards, but I was inspired to do this mashup when I found Rui Wang's open source wearable computing project, which places an RGB, two rechargeable battery options (coin battery, or lipo via JST connector), and a piezo buzzer ('geiger counter' indications of temperature, whee!) all on a beautiful little board. Rui also added a light sensor, an ambient temperature sensor, a button, and has some nice large pin holes for attaching conductive thread. Those might be great things to include here, too, but I figured I'd drop them for now, for simplicity's sake.
My attempt and results
I've created a thermal flashlight board design github repo, where I'm working on an Eagle board. The basic layout idea was this:
Which, on the actual board, came out looking like this:
I've added four holes on the corners of the board -- I'm imagining that it can thus be attached to the end of a stick or cardboard tube, so that it feels like a 'flashlight' -- but then it occurred to me that it'd make a pretty cool "Iron Man"-style device, too:
Thermal fishing bob tie-in. I also figured that I should add a screw terminal to the board to allow for connecting a thermistor probe -- that way the same board could serve as a thermal fishing bob prototype (imagined here as simply sitting inside the translucent plastic 'powdered lemonade' container design, pioneered by Sara and Catherine):
Questions and next steps
Further work on layout and schematic. The design isn't finished yet -- still need to figure out the layout on the board, and I'm thinking that it might be a good idea to put breakout pins for a through-hole RGB LED for the thermal fishing bob case -- so that the LED could be bent at an angle and displaced away from the board, and would be more of a 'beacon' -- rather than being placed in the middle of the board. Also note: for the thermal fishing bob case, we could just opt not to place the IR sensor on the board, to make the design less expensive.
NOTE: in the github repo, the "32u4" design (which I think is where we should head) is the set of schematics / board designs that have "32u4" somewhere in the label.
Kit options. All of the board components are surface mount, except for the IR sensor and the screw terminal. So a good plan might be: have the board produced with only the surface mount components; then, when distributing a kit, include that board + a coin battery, and then additionally include a) the IR sensor, for a 'thermal flashlight' kit, or b) the screw terminal + a thermistor, for the 'thermal fishing bob' kit. Most folks could likely handle soldering those parts on themselves.
Anyone who knows something about Eagle design -- please feel free to download and tweak the board design and play around with the layout!
Why I'm interested
Seems like a single-sided, all-in-one thermal flashlight design would simplify production and reduce costs ... so here's my attempt at that ...