Voltmeter

A voltmeter measures the voltage U between two points, in volts (V). Connect it in parallel with the component or supply you want to measure. Its high input resistance lets it draw very little current; an ideal voltmeter draws none. Swapping the probes in a DC measurement reverses the sign. On this center-zero analog voltmeter, positive voltage moves the needle right and negative voltage moves it left.

For DC voltage measurements, the black lead belongs in COM and the red lead in V. Choose a suitable range and, on a meter with selectable modes, DC voltage. Do not use the current input for this measurement. The voltmeter measures a supply’s voltage; it does not power the circuit.

SparkVille’s clock keeper checks the battery for the tower’s lanterns. The voltmeter stretches its two probes across the battery terminals, and the lanterns stay connected. A little number helps the keeper get everything ready for the evening glow.