Multimeter settings and their uses.

We have different type of meters to measure different electrical parameters like current, voltage and resistance. For measurement of voltage, we have voltmeter. For measurement of current we have Ammeter and for measurement of resistance we have Ohmmeter. Voltmeter is always connected in parallel to the points across which we need to measure voltage. Ammeter is connected in series in the path in which we need to measure the current. Ohmmeter is connected in parallel to a resistance to measure its resistance, but the condition is that the resistance should not be part of circuit. It should be taken out from circuit and then we can measure the correct resistance else will show incorrect data.

Combining all such different types of meters, we get a multimeter. Earlier we had analog multimeter with a dial having different levels marked on it and a needle indicates the values. It was not so easy to read the value in such old analog meters. Since past many years we are now getting digital multimeter which is very easy to read with 7-Segment display. To use a multimeter for measuring different parameters, a selector knob is provided to select different modes like voltage, current or resistance measurement etc. 

Here we will see how to use a basic multimeter which is sufficient for a beginner. Although a large range of sophisticated multimeters are available in market. Every multimeter comes with probes to connect with meter and the other end to the measuring point. Mostly these probe wires are Black and Red in color. Black wire is considered as negative for reference, and connected to “Common” socket in meter. Other than common socket we have two more sockets. As the label suggest, for measuring AC/DC voltage, Resistance and small current up to 200mA we will connect the red probe in middle socket. And for measuring current above 200mA up to 10A, we need to connect the Red probe to top socket labeled as ‘10A’. There are other inbuilt functions also like transistor tester, Square wave generator and a continuity tester.

LCD digital display on the top displays the measured parameters in digits. Around the rotating selector knob we have different range and parameters labeled for selection. We need a 9V battery to operate the multimeter which may be supplied with a new product or you may need to purchase separately and plug it from back side by unscrewing a small cavity provided for it.

Off position disconnects the internal circuit from the battery supply to conserve battery when meter is not in use.

Points to remember while using multimeter:

• No metallic contacts to be touched by hand while measuring any electrical parameters; it could be dangerous while measuring high voltage and high current and may give wrong results while measuring small values.
• We should have idea of what we are measuring, it is AC source or DC source. All supply provided by battery/cells are DC and coming from mains supply is AC.
• We need to have an idea of the value of voltage or current we are measuring. Accordingly we need to select range with the knob. If we are not sure we should start selecting highest range and gradually select lower range, else multimeter may get damaged.

In this multimeter, under DC voltage range we can measure from 200mV to 1000V DC.

Under AC voltage range we can measure 200V AC to 750V AC.

Under DC current range we can measure from 2000µA to 200mA.

Under resistance measurement range, we can measure from 200Ω to 2000KΩ.

For measuring DC current above 200mA we need to select 10A range with red probe in correct socket.

While testing transistor, we need to select range labeled as “hFe”. For testing continuity of any wire, we need to keep the knob at diode symbol.

When we select the square wave “ ” a square wave is generated from meter and the output is available on the probes, with negative at black probe and positive at negative probe.

That’s all about using multimeter. Keep watching for next post.

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