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Emg

Created by @omegon0

July 12th

Used the Hackaday schematic as a starting point. Also added an ESP32 module and some power management (battery charging and power switching is HARD). Schematic is done, just need to add footprints and then make the PCB.

Schematic

Time spent: 4h

July 13th

Fixed all errors and passed ERC. Also added footprints to all components. Threw stuff into PCB, organized everything, and autorouted. Everything fits onto the top layer 65mmx42mm! It's looking more like a gauntlet sort of than a slim band but that's ok since it's using a lot of larger components.

PCB

Time spent: 5h

July 14th

Caught a few mistakes here and there, and generated production files. Still need to mess around with JLCPCB assembly and see what can be done there.

Time spent: 2h

July 15th

Made BOM from scratch because I didn't know Kicad could do it. For the IC footprints that I used, I don't know the pitch... I'll need to fix everything with the INA128.

Time spent: 4h

July 16th

Done with BOM, fixed everything. But there were some crazy high MOQs so I found ones that didn't have that.

Some components are to be hand soldered: resistors and the power switch. The additional BOM is here:

Item Quantity Price Link
JS202011JCQN 1 0.84 https://www.digikey.com/en/products/detail/c-k/JS202011JCQN/6137630?s=N4IgTCBcDaIFIGUwAYUEY1wMIEUByIAugL5A
0805 resistors 1 depends but I have them N/A
tactile switches 2 again, depends but I have them https://www.digikey.com/en/products/detail/cts-electrocomponents/222AMVBAR/5227982
ESP32 S3 N16 1 5.92 https://www.digikey.com/en/products/detail/espressif-systems/ESP32-S3-WROOM-1-N16/16162647
SD0805S020S0R5 1 0.34 https://www.digikey.com/en/products/detail/kyocera-avx/SD0805S020S0R5/3749524

Also J2 is supposed to be a solderable header so nothing is needed there

Problems

I uploaded everything to JLCPCB and it turns out that the ESP can't be mounted with economic assembly so that's another one to add to the list. Diode that I used was a BAT54 but the footprint was 0805 and its better to do that on my own so that's added to this extra BOM Some ICs were rotated -90 degrees so I fixed that in the CLS file

I am now discovering the extended component fee. I'm switching to stencil and doing it myself, and I'll figure it all out tomorrow

Time spent: 6h

July 17

Switching the project to Highway so I can get more funding. I can now get everything assembled in PCBA ideally (except the resistors because JLC genuinely doesn't have most of them) BOM updated to have every part Got renders of the PCB Also there's no case/CAD because electrode placement varies from person to person.

render1 render2

Time spent: 4h

Total time spent: 25h