A voltmeter measures the voltage difference between two points in an electrical circuit. The device usually has a dial, a display, and two probes (red and black). Some voltmeters are analog, while ...

If you’ve never used a voltmeter to test electrical circuits on 12-volt farm equipment, cars or trucks, but wanted to learn, here’s how: Voltmeters cost from $15 to $300. $50 will buy an economy-grade ...