[Dzl] and his rather serious looking son are metal detector enthusiasts ... This one differs by using an Arduino to read from the metal detecting coil. The circuit starts with an oscillator ...

[zaphod] had to research how a metal detector actually works. After reviewing the pros and cons of various approaches, the decision was made to go with a beat frequency oscillator (BFO) circuit.

An embedded process detector circuit which helps Integrated Circuit (IC) developers to address the problem of process variability on low-geometry CMOS designs. The process detector provides the means ...