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. The BOM for my board is here.