Buy one: bit.ly/2OtsJP4
Or many? Who am I to set your limits?
Halp: / marcoreps
This tiny 2MHz Oscilloscope has everything it needs to be a real oscilloscope. Adjustable timebase, V/div setting, a lot of trigger and measurement options and freely draggable cursors.
Open source Arduino ECG Shield with schematic: www.olimex.com/Products/Duino...
2 авг 2017