How to Use Multimeters

Multimeters are the instruments that are designed to measure various electrical parameters. Ammeter, voltmeter and ohmmeter are generally used to read the value of current, voltage and resistance respectively. A multimeter measures all these parameters on a single instrument. This makes it effective and easy to handle. They are of two types; analog and digital multimeter. How to use them and what is the difference in their construction? Well, an analog multimeter measures the electrical parameters with the help of a needle that points to the respective number, that is calibrated on the scale of the analog multimeter. The digital multimeter, on the other hand, displays the output digitally. You can read the output numerically. This avoids the human error that may occur, while taking the reading on an analog multimeter.

Multimeters
Before moving on to understand how to use multimeter, familiarity with the instrument is of utmost importance. So, before going for the details of how to use a multimeter, give a look at all the knobs, start buttons, sockets, etc. and try to understand if you know the functions and uses of these ports/sockets.

Measuring Resistance
For measuring the resistance of a wire, first of all adjust the knob of the multimeter in the resistance range. You can see the symbol of resistance, that is ohms (Ω) on the voltmeter. There are different ranges, provided for the measurement of resistance. For example, R x 10, R x 100 etc, are the ranges that you can set, in order to measure the resistance. Various other ranges that you will mostly find on multimeters are 1.0K, 1.1K, 1.2K, 1.3K, 1.5K, 1.6K, 1.8K, 2.0K, 2.2K, 2.4K, 2.7K, 3.0K etc. If you are not getting any reading in a certain range, then try to select some other range and see if the scale shows a reading for that range, as your resistance wire may be in some other range. Remember that the resistance can only be measured when the device you are testing is not powered. The multimeter may show incorrect readings if the device is powered. You can use your probe either ways, since resistance does not have any direction and so there is no question of polarities. Potentiometers are resistances and their values can be similarly measured.

Measuring Voltage and Current
Voltages are of two types - AC and DC, i.e. alternating voltages and direct voltages respectively. Direct voltage means that, with a change in time, the voltage remains constant. For example, a normal battery source produces a direct voltage of 9V. The alternating voltage means that it changes with time. The graph of voltage vs. time for an alternating current, will be a sine function. This means that the voltage changes at every instant of time. The power supply used in our homes is the alternating current and voltage.

A circuit can only be tested for voltage, if the power supply is on. If there is no power supply, the circuit won't work, and hence the connection is important before taking the reading. Voltage or potential drop is always measured between two points. Always place the ends of the probe between the two points, for which you wish to measure the voltage drop. When asked to measure voltage/current, put the black colored probe (called negative, reference voltage) to the ground (it will be marked or instructed on the circuit) and put the red lead at the point where you would like to measure the current/voltage. This will give you the voltage/ampere reading.

Multimeters are handy electronic tools that are very helpful. The digital multimeters or the analog mulitmeters, both have same features however there is difference in the internal working of both multimeters. Both the properties for both the multimeters are the same, so the electrical parameters can be measured easily using any of them. The digital multimeter displays the output in the form of numbers, as it employs decoders and encoders in the internal circuitry, to represent the data digitally. Analog multimeters, on the other hand, use transducers to produce the desired output. Transducers are the devices that convert one form of energy into other forms. Well, by using a multimeter, you can check the working of a diode by knowing the current flow in the forward and reverse biased direction!