I am new to both Arduino and this Forum so please take it easy on me ;) I'm using Arduino Uno to learn electronics (i'm a computer programmer by trade) and my first project was to follow the below links to create an EMF detector: http://www.instructables.com/id/Arduino-EMF-Detector/ http://www.aaronalai.com/emf-detector
This works perfectly when powered from the Laptop over USB or from a 9v battery. But when I plug it into a USB charger or more importantly into my Raspberry PI then I see the EMF reading jump all over the place and give consistently high readings.
I need to connect to the PI over USB so I can use the USB Serial to send EMF data to the PI. I tried even using the battery at the same time as the USB connection, knowing that the Arduino would use the Battery first. However this still gave the interference.
What I have also found is that touching the USB ground shield drops the interference significantly and therefore I presume this interference is coming from the ground source.
Does anyone have any ideas on how to either stop the ground interference or shield the EMF sensor from it?
Any help is greatly appreciated.