What is multimeter

It also consists of springs attached to the drum which provides an opposing force to the motion of the drum to control the deflection of the pointer. For the measurement of DC, the D Arsonval movement described above can be directly used. However, the current to be measured should be lesser than the full-scale deflection current of the meter. For higher currents, the current divider rule is applied.

Using different values of shunt resistors, the meter can also be used for multi-range current measurements. For current measurement, the instrument is to be connected in series with the unknown current source. For measurement of DC voltage , a resistor is connected in series with the meter, and the meter resistance is taken into account such that the current passing through the resistor is the same as the current passing through the meter and the whole reading indicates the voltage reading.

For voltage measurement, the instrument is to be connected in parallel with the unknown voltage source. For multirange measurement, different resistors of different values can be used, which are connected in series with the meter.

For measurement of resistance, the unknown resistance is connected in series with the meter and across a battery , such that the current passing through the meter is directly proportional to the unknown resistance. For AC voltage or current measurement, the same principle is applied, except for the fact that the AC parameter to be measured is first rectified and filtered to get the DC parameter and the meter indicates the RMS value of the AC signal.

The two main factors affecting the measurement are sensitivity and accuracy. Sensitivity refers to the reciprocal of the full-scale deflection current and is measured in ohms per volt. We mostly used a multimeter is a digital multimeter DMM. It has two probes positive and negative indicated with black and red color is shown in the figure.

The two jacks are utilized when an LCD shows what is being measured volts, ohms, amps, etc. Overload protection prevents damage to the meter and the circuit and protects the user. The Digital Multimeter consists of an LCD, a knob to select various ranges of the three electrical characteristics, an internal circuitry consisting of a signal conditioning circuitry, an analog to digital converter.

The PCB consists of concentric rings that are connected or disconnected based on the position of the knob. Thus as the required parameter and the range are selected, the section of the PCB is activated to perform the corresponding measurement. To measure the resistance, current flows from a constant current source through the unknown resistor, and the voltage across the resistor are amplified and fed to an Analog to Digital Converter and the resultant output in form of resistance is displayed on the digital display.

Similarly to measure an AC or DC, the unknown input is first converted to a voltage signal and then fed to an analog to digital converter to get the desired output with rectification in case of AC signal.

Advantages of a Digital Multimeter are its output display which directly shows the measured value, high accuracy, ability to read both positive and negative values. Here, voltage is the disparity in charge between the two points, the current is nothing but the flow of charge carriers and resistance is the measure of the current flow.

At present, these are available in the market with several functions based on necessity. This article discusses an overview of multimeter and its working with types. A measuring instrument that is used to measure different electrical properties like resistance, voltage and current is known as a multimeter. This is also called a VOM or volt-ohm-milliammeter.

This instrument plays a key role in finding the issues that occurred in the circuits so that we can easily troubleshoot the issues.

Multimeter includes a rotary switch on the front panel, used to select different electrical parameters to measure electrical properties. These are classified into two types like analog and digital which are discussed below.

The multimeter diagram is shown above that includes three parts like display, knob, and ports. Generally, the display on the multimeter includes 4 digits which display a negative sign.

Some types of meters include illuminated displays which display clearly in less light conditions. The selection knob is used to allow the operator to fix the multimeter to examine several parameters like current, voltage, and resistance.

The multimeter has two probes like black and white which are inserted into two ports on the front side of the meter. This kind of probe is usually in black color however there is no dissimilarity among the two probes like red and black except the color. A special port on the multimeter like 10A is mainly used where the measurement of a large current is required above mA. These probes include a connector in the banana shape on the end-user to plug on the multimeter.

Log in Sign Up. Save Word. Definition of multimeter. Examples of multimeter in a Sentence Recent Examples on the Web If this is your first time using a multimeter to read electrical data, Pop Mech has a handy how-to guide here. First Known Use of multimeter , in the meaning defined above. Learn More About multimeter. Time Traveler for multimeter The first known use of multimeter was in See more words from the same year. The voltage or other value will read out on the tester.

Multimeters are safe to use on energized circuits and equipment, provided the voltage or current does not exceed the maximum rating of the tester. Also, you must be careful never to touch the bare metal ends of the tester leads during an energized test because you can receive an electrical shock.

Multimeters are capable of many different readings, depending on the model. Basic testers measure voltage, amperage, and resistance and can be used to check continuity, a simple test to verify a complete circuit.

More advanced multimeters may test for all of the following values:. Accessories or special sensors can be attached to some multimeters for additional readings, such as:.

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