DIY ULTRA-SENSITIVE EMF (Electromagnetic field) Detector
https://maker.pro/arduino/projects/diy-ultra-sensitive-emf-electromagnetic-field-detector
This device can also be called an EMF meter, as it can measure the relative strength of a field using a scale of 10 LEDs.
DIY Simple Arduino EMF (electromagnetic field) Detector
https://maker.pro/arduino/projects/diy-simple-arduino-emf-electromagnetic-field-detector
The emf detector described in this video has a minimal number of components, which means that it is simple to make, and does not require any tuning. It works great right from the first power on.
Electromagnetics: How to Make a Powerful DYI Coil Gun
https://maker.pro/custom/projects/make-coil-gun-without-camera
Learn how to make an electromagnetic projectile launcher without a camera.