Hays Bridge Circuit: Hays Bridge Circuit, shown in Fig. 11.23, differs from Maxwell’s bridge by having a resistance R1 in series with a standard capacitor C1 instead of a parallel. For large phase angles, R1 needs to be low; therefore, this bridge is more convenient for measuring high-Q coils. For Q = 10, the error is […]
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Maxwell Bridge Theory: Maxwell Bridge theory, shown in Fig. 11.21, measures an unknown inductance in terms of a known capacitor. The use of standard arm offers the advantage of compactness and easy shielding. The capacitor is almost a loss-less component. One arm has a resistance R1 in parallel with C1, and hence it is easier
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Comparison Bridge: There are two types of Comparison Bridge, Namely Capacitance Comparison Bridge Inductance Comparison Bridge 1. Capacitance Comparison Bridge: Figure 11.18 shows the circuit of a capacitance comparison bridge. The ratio arms R1, R2 are resistive. The known standard capacitor C3 is in series with R3. R3 may also include an added variable resistance
Block Diagram of Wheatstones Bridge with Digital Readout: The tremendous increase in the use of digital circuitry has had a marked effect on electronic test instruments. The early use of digital circuits in bridges was to provide a Digital Readout. The actual measuring circuitry of the bridge remained the same, but operator error in observing
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Bridge Controlled Error Detection: Bridge Controlled Error Detection – Whenever a bridge is unbalanced, a potential difference exists at its output terminal. The potential difference causes current to flow through the detector (say, a galvanometer) when the bridge is used as part of a measuring instrument. When the bridge is used as an error detector
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Kelvins Bridge and Kelvins Double Bridge: When the resistance to be measured is of the order of magnitude of bridge contact and lead resistance, a modified form of Wheatstone’s bridge, the Kelvins Bridge is employed. Kelvins Bridge is a modification of Wheatstone’s bridge and is used to measure values of resistance below 1 Ω. In low
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Wheatstone Bridge Diagram: A Wheatstone Bridge diagram in its simplest form consists of a network of four resistance arms forming a closed circuit, with a dc source of current applied to two opposite junctions and a current detector connected to the other two junctions, as shown in Fig. 11.1. Wheatstone Bridge diagram are extensively used
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pH Measurement Methods: pH is defined as the negative logarithm of the active hydrogen ion. It is a measure of the acidity or alkalinity of an aqueous solution. The pH scale runs from 0 – 14, with pH 7, the neutral point, being the pH of pure water at 25°C. The lower the pH value,
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Megger Circuit Diagram: Another common method of measuring resistances above 50 M Ω is the Megger Circuit Diagram (megaohmmeter) shown in Fig. 10.23(a). This instrument is used to measure very high resistances, such as those found in cable insulations, between motor windings, in transformer windings, etc. Construction and Working Principles: Normal (shop) VOMs do not
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Transistor Tester and its characteristics: The term Transistor Tester (or analyser) used in this text is for instruments giving quantative measurements of transistor parameters. The tester should be able to provide direct readings for at least two important measurements, such as: A value for the forward gain in the common emitter configuration (hFE for ac gain
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