After the depressing reality of my broken $300 PCBs, I decided to take a new tack. I wanted to try my hand at assembling these myself, so I build a slightly simplified version that had more through hole components. I still went with SMD ICs, though I chose SOIC packages, as they seemed like the easiest SMD package to solder at the time.

These boards are glued to laser cut stands from ponoko, and can be seen fully assembled on the main happyfuntouch page.

In addition to this, the boards are designed to be daisy chained together for ease of connection to a microcontroller. Daisy chained shift registers enable individual LED switching and control the enable bit of each multiplexer. 4 IO lines select the channel on the active multiplexer and are shared among all boards. Each board contains 16 multiplexed phototransistors and 6 IR LEDs.

The complete design can be seen both on the happyfuntouch page and in the picture below. It’s not easily seen, but there is a 3mm acrylic waveguide sitting on the laser cut stands. (all the optoelectronic elements are optically coupled to it)

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