Voltmeters aren’t terribly expensive, but it’s always more fun to build your own devices. YouTube DIYer Educ8s builds a cheap voltmeter for less than $10 using an Arduino and a voltage sensor.

The voltmeter has a fixed measurement range from 0 to 100 VDC, the only switches on the board are for powering it on and a hold button, which freezes the value currently being shown in the three ...