Voltmeters and Multimeters

Multimeter uses and Functions

Multimeter uses and Functions: A multimeter is basically a PMMC meter. To measure dc current the meter acts as an ammeter with a low series resistance. Range changing is accomplished by shunts in such a way that the current passing through the meter does not exceed the maximum rated value. Let us discuss Multimeter uses …

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Multirange Ohmmeter

Multirange Ohmmeter: The Multirange Ohmmeter circuit shown in Fig. 4.28 (a) is only for a single range of resistance measurement. To measure resistance over a wide range of values, we need to extend the ohmmeter ranges. This type of ohmmeter is called a multirange ohmmeter, shown in Fig. 4.29.   Shunt Type Ohmmeter The shunt …

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Series Type Ohmmeter

Series Type Ohmmeter: Series Type Ohmmeter – A D’ Arsonval movement is connected in series with a resistance R1 and a battery which is connected to a pair of terminals A and B, across which the unknown resistance is connected. This forms the basic type of series ohmmeter, as shown in Fig. 4.28 (a). The …

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True RMS Voltmeter

True RMS Voltmeter: True RMS Voltmeter – Complex waveform are most accurately measured with an rms voltmeter. This instrument produces a meter indication by sensing waveform heating power, which is proportional to the square of the rms value of the voltage. This heating power can be measured by amplifying and feeding it to a thermocouple, …

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Average Responding Voltmeter

Average Responding Voltmeter: A simplified version of a circuit used in a typical average responding voltmeter is given in Fig. 4.23. The applied waveform is amplified in a high gain stabilised amplifier to a reasonably high level and then rectified and fed to a dc mA meter calibrated in terms of rms input voltage. In …

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AC Voltmeter using Rectifiers

AC Voltmeter using Rectifiers: AC Voltmeter using Rectifiers – Rectifier type instruments generally use a PMMC movement along with a rectifier arrangement. Silicon diodes are preferred because of their low reverse current and high forward current ratings. Figure 4.16 (a) gives an ac voltmeter circuit consisting of a multiplier, a bridge rectifier and a PMMC …

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DC Standard Differential Voltmeter

DC Standard Differential Voltmeter: A basic DC Standard Differential Voltmeter can be operated in different modes. The three basic modes of operation are as a dc voltage standard, as a dc differential voltmeter, and as a dc voltmeter (conventional). 1.DC Voltage Standard: A + 1 V dc stable supply is obtained from a temperature controlled …

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Differential Voltmeter

Differential Voltmeter: The Differential Voltmeter technique, is one of the most common and accurate methods of measuring unknown voltages. In this technique, the voltmeter is used to indicate the difference between known and unknown voltages, i.e., an unknown voltage is compared to a known voltage. Figure 4.14 (a) shows a basic circuit of a differential …

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