Build the "TAPIR" electrosmog detector
The TAPIR — Totally Archaic but Practical Interceptor of Radiation — is an E-smog detector capable of detecting and audibly pinpoint any source of electric or magnetic field. Its application area extends from home use to professional use. It’s even suitable as a first SMD soldering project — with your (grand)child — since it’s so easy (and fun!) to assemble.