With multiple uses, these devices typically combine the functions of a Voltmeter, Ammeter, Ohmmeter to measure the voltages that pass in a circuit, the current in the circuit or the resistance of the circuit. There are the analog multimeters that nowadays have fallen into disuse due to the appearance of DMM - the first ones used a galvanometer to present the values read in an analogical way.
In the world of digital multimeters there are those that need to be fixed to scale and those that have a scale that adjusts itself to the values that are being read.
The Multimeter is generally composed of three parts:
- the Display;
- a Selector;
- the Ports.
The Display is responsible for displaying the values that are being read.
The Selector allows you to establish how the Meter is operating.
In the ports the probes are connected so that it is possible to touch the components, circuits or plugs where the measurement is to be made.
It is the fundamental tool for any activity related to electrical or electronic circuits. The costs of these equipments range from a mere 5 euros to a few hundred. This depends, of course, on the accuracy of measurements that are being taken as well as on the types of values that are to be read.
- Measure the value of resistors. It is important to note that the values when the resistance is mounted in a circuit may be different from the isolated measurement of the same resistor.
- Check the conductivity of the circuit. In this mode it is also possible to check LEDs.
- Measure Voltages. The multimeter measures both positive and negative voltages (if the probes are switched the read value appears negative)
- Measuring Currents. In order for the currents to be measured, the multimeter must be placed in series with the current circuit.
Multimeters typically come with a fuse so that when something goes wrong in the measurement, the fuse will “burn” and not all of the equipment electronics. If it isn’t working check the battery and also the fuse.
Functions that may influence the choice of a multimeter:
- Have self-adjusting scale;
- Have Backlight;
- Have auto-off;
- Have decent probes.