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DIY Electrolysis - Assembly
Components
There are several parts you need to source yourself. These are as follows:
- 4x M3 14-18mm countersunk screws
- Tens pad
- Tens cable (with the pin connector and 2.5mm jack)
- 0.96in SSD1306 OLED (colour doesn't matter, but the pins do! Ground, VCC (power), SCL, SDA.)
- 2x 3.5mm jack
- Foot pedal (optional, but strongly recommended)
- Enough wire for the stylus and foot pedal (I used about 3m total for the foot pedal and 1m total for the stylus)
- D-Sub Female Contacts (24-20 AWG, loose and not in a connector)
- Electrolysis needles, see usage page on what to buy
- 3.7V 350mAh 1S LiPo battery with JST-PH connector
The D-subs can be annoying to get. I got some Harting ones from eBay, but other electronics retailers like CPC, Farnell, DigiKey, and Mouser should stock them. They vary in shape but should all work as long as they are the individual contact and not a whole connector.
The needles themselves are consumables and can be expensive. Both Ballet and Sterex will work. I recommend F4/F4S needles since they're a little more versatile but F5 should work too and might be a little better for coarse hair.
Assembling the PCB
Place the OLED and battery into their respective connectors on the PCB. Make sure your battery connector has the correct polarity, you can just make sure the red wire connects to the + on the board and the black one to the -. You should also make sure the OLED's pins match what is on the board, or you could fry it.
Soldering the pedal and stylus
The D-sub (needle holder for the pen, aka the follicle electrode) should be connected to all the connections on a 3.5mm jack with approx. 1m of wire.
If you are building the optional foot pedal, then the normally open (NO) terminal of the foot pedal switch should be soldered to the tip of the other 3.5mm jack with approx. 1.5m of wire, and the common (C) terminal to the sleeve of the same jack with the same amount of wire.
3D Printing
Print the parts in the 3dprint folder in the repo. The parts are designed to be printed with a layer height of 0.2mm and 20% infill with a 0.4mm nozzle and should not require supports when printed in the provided orientation. PLA is suitable.
Put the PCB with screen and battery into the main/top piece and secure the bottom piece over it with four M3 screws. If you have no screws, glue is ok.
Put the soldered D-sub with wire into one half of the printed stylus and glue it in place. Wait for the glue to cure before gluing the other half of the stylus. Once the stylus is assembled, you can (CAREFULLY!) put a needle in.
Firmware
Pre-compiled release firmware is in the Github releases page. You can also download the source and compile it yourself.
Plug the board into your computer via the USB-C port. It should enter DFU mode automatically if it's the first time it is being flashed, but if it isn't you can make it enter DFU by holding down the BOOT button and while holding it, briefly pressing RST and then letting go of BOOT.
Mac OS & Linux
Install dfu-util using your package manager of choice. On Mac, use Homebrew: brew install dfu-util
Then, in the terminal, run: dfu-util -a 0 -s 0x08000000:leave -D firmware.bin
Windows
Install stm32cubeprogrammer from ST's website. Open it and in the top right drop down menu set it to USB mode.
Then, click Connect. Click the Open file tab and select firmware.bin. Set start address to 0x08000000. Click Download.
You can also use Zadig with the WinUSB driver and dfu-util.exe.