Just when you thought you’d seen an Arduino do everything, [birdyberth] built an Arduino powered Electrocardiogram (ECG or EKG). Electrocardiography is a non invasive method of studying the h… ...

Since the ECG is many times more sensitive to EMF than the Arduino, this turns out to be a quick and easy way to make sure he’s not barking up the wrong tree.

Back to the design description, the D13 signal output pin (TP4), which is logic-low (L) by default, shifts to a logic-high (H) state for a while when an object appears within sight of the infrared ...