After some searching, I ended up using a microcontroller and a piece of code borrowed from the web that I tweaked and adapted. The microcontroller-based concept was chosen because I wanted to scale ...

An Arduino can measure time, a coil and a resistor will create a delay proportional to the circuit values, and metal around the coil will change the coil’s inductance.

Mitsubishi Electric Corporation (TOKYO:6503) announced today that it has developed what is believed to be the world's first* compact metal corrosion s ...