Nowadays, single measuring devices are becoming less and less common on the market. Multifunctional meters called multimeters are in widespread use. These devices combine various measuring instruments in one housing.

A multimeter is equipped with two test probes, usually black and red. The black probe is always connected to the black COM socket (common), while the red probe is connected to one of the three red sockets of the meter, depending on the measurement we want to perform and the meter model. The maximum permissible voltages and currents for individual sockets depend on the meter model, so you should always make sure that the voltage or current connected to a given socket does not exceed the maximum values of the multimeter. In addition, when measuring an unknown voltage or current source, for safety, select the highest measuring ranges.