The multimeter consists of the union of three measurement tools (voltmeter, ammeter and ohmmeter) in one. This multiple instrument allows to measure voltages of alternating currents (AC), direct currents (DC), resistance, continuity, temperature, capacitance, transistors, etc. There are also multimeters with many more options such as oscilloscope, signal generators, among others. exist multimeters analog (with needle) and digital. Lately the most used are the digital ones, but without forgetting the analog ones that are also still used since they provide a faster response thanks to the movement of the needle.
In a previous article we discussed this versatile instrument in a general and introductory way. In this article we will indicate in detail how to use the Multimeter to obtain the desired measurement.
How to use a multimeter?
In the first place, you must always know what you are going to measure, in order to position the switch in one way or another.
The device has two terminals whose polarities are characterized by colors: Black (-) Y Red (+).
We can find mainly four types of measurements.
- AC V. Which is used for the measurements of alternating current voltages expressed in volts.
- DC V. For measurements of voltages of a direct current that is expressed in volts.
- DC A. For direct current voltages it is expressed in milliamps on the device.
- Ohms They are used to measure electrical resistance and check continuity in circuits.
Measuring electrical resistance with a multimeter
- Position the selector key on the sign “W“In such a way that the Multimeter becomes an Ohmmeter.
- Place the appropriate scale according to the size of the resistance to be measured. If you do not know the amount of ohms that the resistance to be measured has, you should start by placing the largest scale, and then gradually reduce until you get the scale that provides the best precision within the range.
- Take a resistor and connect the terminals of the apparatus at the ends.
- The number that appears on the screen will be the resistance value in Ohm (W).
Measuring AC voltage with a multimeter
- Set the selector to the function CV A highest.
- Touch the NEUTRAL side of the circuit with the tip of the black test probe.
- Touch the phase side of the circuit with the red test lead.
- The number that appears on the screen will be the voltage value. (V)
- If what you want to measure is absolute voltage, place the black terminal or probe on any ground, and the other probe on the point to be measured. If what you want is to measure voltage differences between two points, you only have to place one probe at each point.
Measuring AC current with a multimeter
- Attach the black test lead to the negative type (COM) connector.
- To measure currents up to 200μA DC, set the function switch to 200μA DC. Then insert the red wire into the type connector (uA / mA)
- After cutting off the power to the circuit, open the circuit where you want to measure the current.
- Using the black probe tip, test the negative side of the circuit.
- With the red tip the positive side.
- Apply power to the circuit and the result will be displayed on the screen.
Measure temperature with a multimeter
- Set the selector switch to position TEMP.
- With the temperature probe inserted in the “COM” and “V” connectors
- Use the ° F / ° C buttons for the desired temperature unit.
- With the head of the temperature probe, touch the part where you want to measure and keep the probe in contact until the reading stabilizes.
- The measured temperature will appear on the display.
Other functions of multimeters
There are some mutimeters designed to perform more advanced functions, such as:
- Create and detect the intermediate frequency of a device, and an amplifier circuit with a loudspeaker to aid in the tuning of circuits of said devices. They also allow the signal to be tracked through all stages of the receiver under test.
- They work like oscilloscope over a million samples per second in scanning speed, and with high resolution.
- Synchronization with other measuring instruments, including others multimeters, to carry out specific power measurements (Power = Voltage * Intensity).
- They can be used as a telephone set, to connect to a telephone line under test, during measurements on the same or an adjacent one.
- Check car electronics circuits. High or low voltage burst recording.
These measurement tools they are very useful, and widely used and applied. Are tools practical, portable and versatile, and very effective.