u/gcappaert

Not sure how many actual orthos patrol this subreddit, but here is my question:

Let's say a patient needs a total knee replacement. This particular patient is an archaeology fanatic. She already has plans to be interred in a peat bog or bone dry desert to preserve her remains for as long as possible in hopes that future archaeologists will one day dig her up.

If that patient asked you very nicely to engrave a short message into the cortex of her tibia during the surgery, would you do it?

This is my first ever circuit/PCB that is more complex than a basic LED or something.

It's a DIY magnetic stir plate using stationary electromagnets rather than a magnet stuck to a computer fan (which seems to be a common DIY method). I wanted to try this because it seemed like a good way to learn some electronics and because the fan approach seems inelegant.

Power supply: 12V/2A switching wall wart

Electromagnets: ~150 coils of 24G magnet wire on 5mm soft iron core

PCB is a single layer to make it easy to produce on my desktop CNC.

I have made a couple drafts/prototypes and have gotten here. It spins the magnetic stir bar, though there are some issues I still need to work on: the MOSFETs get hotter than I'd like and the stir bar loses coupling pretty easily. Interested in any advice about how to improve my circuit and PCB layout (though still limiting it to one layer). Thank you!

schematic

pcb (red zone is power, blue zone is ground)

Wasn't sure whether to post here or to r/PCB but this seems like the better place to get feedback