single channel arduino ~150kHz oscilloscope
This is a single channel oscilloscope using arduino capable of ~150kHz sampling rate on ATmega328 with 16Mhz crystal.
It is heavily based on Girino project by Cristiano Lino Fontana (http://www.instructables.com/id/Girino-Fast-Arduino-Oscilloscope/).
This is the arduino code for the project, it samples the input and sends the data over usb serial to computer.
It was tested on Arduino Uno and while a bit jittery it does work at ~150kHz.
You can find the small-scope shield and software in their repos.