The git repo should be pretty well up to date, but I forgot to grab an image of the schematic. I also updated the BOM spreadsheet to include most of the components. Highlights:
- Changed to a 3.3VDC boost converter. I should be able to run a single CR2032 pretty much down to nothing that way. This one appears to fit the bill, provides enough current, doesn't need a lot of external parts, etc.
- Moving to 3.3VDC means taking a smaller voltage drop across the resistors, so the whole deal should be more efficient. I mathed it out a bit too and it appears that a 68-ohm resistor will work for all of the LED elements (the higher voltage drop InGaN devices also consume proportionally less current, which is _great_). That means I can use common-bus resistor networks to hopefully save some space on the board!
- Still using shift registers (verified they work at 3.3vdc) and an ATtiny85. It looks like the 595s sink the same current high and low, so I'm going to stick with the common-cathode LED configuration at this point.
- Added a hardware on-off switch between the battery and the converter. I like switches.
I'll post a fresh image at some point, but I'll probably get to work on layout soon. I have around half of the pad patterns sorted, so that shouldn't be too far off. Hopefully it all fits in 1 in^2.
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Ah hah! I was Feed-Lagging. Nice work!
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heh -- <old-fart voice> Back in my day, LEDs were rated for 20mA, but if you actually wanted to *see* it, you wouldn't settle for less than 30... You spoiled kids!</old-fart voice>
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Hahaha take that LEDs! Boom!
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