A very simple oscilloscope based on STM32F103 MCU that anyone could build designed by Martin Loren.
I designed a small pcb that sits on top of a STM32F103 module (blue pill). It’s the HS101 version and I used a 3.5mm female jack as the probe input.
Enter your email to download the gerber files for my pcb and the .stl files for the enclosure. The BOM for my board is here.