voltmetros

A voltmeter is a measuring instrument used to determine the electrical potential difference between two points in an electric circuit. It is a fundamental tool in electronics, electrical testing, and power systems, allowing technicians and engineers to quantify voltage levels for design, troubleshooting, and validation.

Volmeters come in two broad families: analog and digital. Analog voltmeters display a continuous value on a moving scale, typically using a galvanometer and a high input resistance to minimize circuit loading. Digital voltmeters (DVMs) sample the signal with an analog-to-digital converter and present a numerical readout, often with auto-ranging and higher input impedance. Some instruments combine both functions in a multimeter.

Measurement principle and connection: a voltmeter is placed in parallel with the element or portion of the circuit whose voltage is to be measured. In an ideal voltmeter, the input resistance is infinite, drawing no current. Real voltmeters have finite input impedance, which can load the circuit and introduce measurement error, especially in high-impedance or sensitive circuits. Many modern digital meters provide input impedances of 1 MΩ or greater to reduce loading.

Ranges and accuracy: voltmeters offer selectable voltage ranges. Accuracy is specified as a percentage of reading and often includes a range-dependent error plus a temperature coefficient. True-RMS digital voltmeters can measure non-sinusoidal waveforms more accurately than simple average-responding meters.

Applications: voltmeters are used in laboratories, field service, electrical maintenance, and manufacturing for DC and AC voltage measurements, circuit verification, and safety checks. The term derives from the volt unit, named after Alessandro Volta.