How a Multimeter Works

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Although, at first look, a multimeter looks very much complicated with its port panels, dials, displays, and buttons, yet once you become familiar with its workings, it becomes extremely convenient and handy. 

Multimeters are typically utilized by electricians and electronic professionals to test the voltage of circuits that need work or for troubleshooting circuits to find the source of the problem. Testing a circuit with a multimeter prevents a person from becoming subject to any electric shock. It also enables you to pinpoint the exact source of trouble within an electric circuit.

Nonetheless, electricians aren’t the only ones that can use a multimeter. You will find multimeters created for residential use. Commercial multimeters are accessible in both analog and digital forms and might conveniently be utilized by anyone. 

Multimeters are categorized into two types depending on the way the measurement is displayed: analog and digital. Analog multimeters are considered to be multifunctional electrical measuring tools with indication by any means of an arrow scale. 

Most multimeters innately measure voltage and pass a current to be measured via a shunt resistance. It measures the voltage made across it. The voltage drop is considered as the burden voltage, quantified in volts per ampere. 

This article will explain how a multimeter works both concerning analog and digital multimeters and how to use it to test different characteristics of an electrical circuit. 

How does an analog multimeter work? 

An analog multimeter is a permanent magnet moving coil meter type of measuring instrument. It works on the d’Arsonval galvanometer principle. This multimeter features an analog display that utilizes the deflection of a pointer on the scale to show the level of measurement being done. The pointer then deflects from its first position increasingly as the measuring quantity rises. 

Given that an analog multimeter belongs to the PMMC type of instrument, the coil moves in the magnetic field created by the permanent magnet when a current is passed through its coil. A pointer is then linked with the coil.

A deflecting torque functions on the coil when the current flows in it, and it will rotate it by an angle. Hence, the pointer moves over a scale. Take note that a pair of hairsprings is connected to the spindle to offer the controlling torque. 

A standard analog multimeter can measure the following quantities:

  • Resistance
  • DC current
  • AC voltage
  • DC voltage

The analog multimeter functions as an ammeter along with a low series resistance to measure DC. A shunt resistor is attached in parallel with the galvanometer for high currents measurement. An analog multimeter can measure currents within the ranges of amperes or milli-amperes along with the shunt resistor. 

Adding multiple resistors allows an analog multimeter to become a voltmeter. It can then be utilized for the measurement of DC voltages within the ranges of kilovolts or millivolts. 

Adding a network of resistors and battery enables this multimeter to work as an ohmmeter as well. Different values of resistance can be measured by adjusting the value of shunt resistance in the resistor network. Further, the AC currents and voltages could be measured by adding a rectifier unit in the analog multimeter circuit. 

An analog multimeter is relatively simple to use. It’s only necessary to understand how to use the analog multimeter with the knowledge of how to make resistance, current, and voltage measurements. There’s no need for batteries in this multimeter if you like to measure voltage and current.

But if you measure a resistance, batteries should be used in the multimeter.

How does a digital multimeter work?

On the other hand, a digital multimeter is a measuring device utilized to measure different electrical amounts. The standard measurements done by a digital multimeter are resistance, voltage, and current. Apart from those, a digital multimeter can also measure transistor gains, continuity, capacitance, frequency, and temperature, among others. 

A digital multimeter converts a DC voltage signal through a conversion circuit and then uses an A or D converter to convert the signal into a digital quantity. The digit is measured by an electric counter and finally shown on the screen.

The function of a multimeter to measure resistance, current, and voltage is partially realized with the conversion unit. The measurement of resistance and current are all based on the voltage measurement. It indicates a digital multimeter is created on the basis of the digital DC voltmeter. 

The A or D voltmeter then converts the analog voltage quantity that changes unceasingly with time into a digital quantity. Moreover, an electronic counter measures the digital quantity to acquire the measurement result, and a decoding display circuit shows the measurement result.  The logic control circuit regulates the coordinated work of the circuit and finishes the overall measurement process in order under the action of the clock. 

Final Thoughts

A multimeter works using two probes, one black, and one red, that connect on the front of the multimeter. The black lead inserts into the COM slot while the read led plugs to the mAV slot. Above the slots for the leads is a dial for changing the setting of the multimeter. The various settings are different characteristics to be tested. 

For digital multimeters, you will find a display offering a detailed reading of whatever aspect of an electric circuit is tested. On the other hand, an analog multimeter offers a meter display that moves to give the data of what’s being tested.

The black and red lead have probes attached to the end, and these are utilized to link to the different individual parts of the circuit for testing. 

A multimeter you use must be of high accuracy and quality. Make sure you authenticate that your multimeter conforms to all safety regulations. You will find many different types of digital multimeters based on the application and range of functionality.

Depending on whether you like it for industrial use or general purpose, you need to learn some trusted multimeter brands to get a high quality product. We hope you find this article engaging and informative as well. 

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