Just a little update to keep you guys in the loop.
There is quite a lot of private stuff going on with me right now, so development is super slow. But I think I have the PCB schematic now where I want it to be. I had a **** ton to learn about ESD and EMI management I had not payed attention to so far, but I want to deliver the best product possible so I read through a wealth of forum posts and company white papers.
PSA: if my research is correct, most split keyboards are NOT ESD SAFE!
An ESD is a high voltage and therefore high energy pulse shocking a system due to electro static discharge. It is the same as touching a door handle and getting shocked. The Let's Split, Levinson Rev2 and Corne PCB all do not have ESD protection on the TRRS jack. Touching the contacts of the TRRS plug can easily raise the voltage level to several thousand volts and fry the circuits on the PCB.
Disclaimer: I think this should only be possible if the PCB has an active ground connection, meaning the USB is plugged in or there is another connection to ground, and if a TRRS contact other than the ground (usually sleeve) receives the ESD. Also I am a novice regarding this topic and have not done any actual ESD testing so far. I will however install the recommended measures to the Ellipsis PCB, since that boils down to just adding appropiate TVS ICs between signal path and ground.
Besides that figuring out how to connect the main cluster PCB to the PCB for the angled part took some tinkering and digging around. Since the angled PCB is not symmetrical but mirrored between sides I wanted to have it be flippable. I think I have a solution which should work, but I will have to see during actual layout if I have the space.
Speaking of space, there needs to be another revision for the top parts of the case to add more space for the angled PCB, which is currently to small for Kailh hotswap sockets.
And last but not least the angled part should support an encoder in any of the three positions and there might even be up to 8 different encoders available in the main cluster. This depends on a new QMK feature and I am not 100% certain that this will work as I currently understand. Fingers crossed that everything works out.