Use an Arduino microcontroller to sense invisible electromagnetic fields using wire, a resistor, and an LED.
Aaron ALAI’s EMF detector project is awesomely simple to make and fun to use. An upgraded version can be built using an LED bargraph for more ‘meter-like’ functionality.
original project can be found here –
additional info, and Arduino sketch –
audio/video by Collin Cunningham
Duration : 0:3:23