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.

[Brett] from [Theoretically Practical] has done with his old MIG welder, adding premium control features with the help of an Arduino. The main features [Brett] were after is pre-flow, post-flow ...

LittleBits is aware of just how intimidating these make-it-yourself gadgets can be, so it has just launched its first software-programmable module, the Arduino at Heart.