An ATmega328 based portable home made oscilloscope with ADC from Creative Engineering:
It is basically a small scaled digital oscilloscope. It is capable of displaying all type of waveform like sine, triangular, square, etc. It’s bandwidth is above 1 MHz and input impedance is about 600K. The device is mainly using the ATmega328 micro-controller as the heart and is assisted by a high performance ADC (TLC5510) which is capable of taking up-to 20 mega samples per second and thus increasing the span of bandwidth which can be analyzed by our device. In addition to that, in-order to make the device portable Li-ion battery is used , which will be suitable to be fitted into a confined space.
See project details on Creative Engineering blog.
Check out the video after the break: