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 ...
The circuit in this Design Idea makes a voltmeter that reads to 0.99V. The idea uses a counter IC to drive two sets of four LEDs (Figure 1). Each of these two sets represents a BCD ...