Here is a useful circuit for Arduino lovers and experimenters. It is a simple digital voltmeter, which can safely measure input dc voltages in 0 to 30V range. The Arduino board can be powered from a ...

[Artlav] wanted to build a digital camera, but CCDs are expensive and don’t respond well to all wavelengths of light. No problem, then, because with a photodiode, a few stepper motors, the obligatory ...