I would like to build an emf detector like this and then connect it to a raspberry pi, I believe I can connect it through an adc which I know how to build so I just need help building the circuit.
http://io9.gizmodo.com/5875212/meet-the-emf-meter-the-little-tool-that-ghost-hunters-swear-by
http://io9.gizmodo.com/5875212/meet-the-emf-meter-the-little-tool-that-ghost-hunters-swear-by