DC Voltmeters

jojo August 13, 2017 2 Comments
DC Voltmeter Block Diagram DC voltmeter mainly consists of a dc ampli­fier apart from the attenuator, as shown in figure.   DC voltmeters can further be divided into two categories. 1. Direct Coupled Amplifier DC Voltmeter This type of voltmeter is very common because of its low cost. This instrument can be used only to measure voltages of the order of milli-volts owing to limited amplifier gain. The circuit diagram for a direct coupled am­plifier dc voltmeter using cascaded transistors...
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Electronic Voltmeters

jojo September 22, 2009 3 Comments
In all electronic voltmeter circuits the principle involved is that an indication on a permanent magnet moving coil instrument (normally abbreviated as PMMC or D’Arsonval movement) proportional to the input voltage is obtained by means of amplification in one or more stages with a high input impedance. Although electronic instruments are usually more costlier than electrical instruments but are becoming more and more popular because of their numerous advantages over conventional ones, as discussed below : A moving coil...
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Electronic Galvanometers

jojo August 17, 2009 No Comments
An electronic galvanometer is a vacuum tube or transistor amplifier, followed by a milli ammeter may be employed as a detector. Some devices have arbitrary scale values, sometimes with variable gain and are designed simply as balance detectors. Sensitivity of such devices may be of the order of a microvolt per scale division or better, and the input  impedance is in the range of megaohms, so the current drawn from the measured source is usually negligible. Such instruments have...
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