Introduction to instruments
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- Unit: VI Hrs: 07
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- BRIDGES
- Advantages of Bridge Circuit
- Wheatstone’s bridge
Frequency Synthesizers:The frequency generators are of two types. One is free running frequency generators in which the output can be tuned continuously either electronically or mechanically over a wide frequency range. The generators discussed uptill now are of this type. The second is frequency generator with frequency synthesis technique. The synthesis means to use a fixed frequency oscillator called reference oscillator or clock and to derive the wide frequency range in steps from the ou tpu t of the reference oscilla tor. The stability and accuracy of free running frequency generator is poor while frequency synthesizers provide output which is arbitrarily selectable, stable and accurate frequency. The reference oscillator used in frequency synthesizers is generally precision crystal oscillator with an output at some cardinal frequency such as 10 MHz. Various signal processing circuits then operate in synchronism to provide a large choice of the output frequencies. Recommended questions:State the requirements for systhesizer? [jan 07,09 jul 05, 08] Draw the basic block diagram of signal generator. [asked in almost every paper] What is sweep frequency generator? [jun 06] What is function generator? [jan 05] Unit:VI Hrs: 07Syllabus: Measurement of resistance, inductance and capacitance Whetstone’s bridge, Kelvin Bridge; AC bridges, Capacitance Comparison Bridge, Maxwell’s bridge, Wein’s bridge, Wagner’s earth connection (Text 1: 11.1 to 11.3, 11.8, 11.9, 11.11, 11.14 and 11.15 )
“Electronic Instrumentation”, H. S. Kalsi, TMH, 2004 “Electronic Instrumentation and Measurements”, David A Bell, PHI / Pearson Education, 2006. UNIT IVBRIDGESIntroduction: A bridge circuit in its simplest form consists of a network of four resistance arms forming a closed circuit. A source of current is applied to two opposi te junctions. The current detector is connected to other two junctions. The bridge circuits use the comparison measurement methods and operate on null-indication principle. The bridge circuit compares the value of an unknown component with that of an accurately known standard component. Thus the accuracy depends on the bridge components and not on the null indicator. Hence high degree of accuracy can be obtained. Advantages of Bridge Circuit:The various advantages of the bridge circuit are, The balance equation is independent of the magnitude of the input voltage or its source impedance. These quantities do not appear in the balance equation expression. The measurement accuracy is high as the measurement is done by comparing the unknown value with the standard value. The accuracy is independent of the characteristics of a null detector and is dependent on the component values. The balance equation is independent of the sensitivity of the null detector, the impedance of the detector or any impedance shunting the detector. The balance condition remains unchanged if the source and detector are interchanged. Wheatstone’s bridge:The bridge consists of four resistive arms together with a source of e.m.f. and a null detector. The galvanometer is used as a null detector. 
The arms consisting the resistances R] and R2 are called ratio arms. The arm consisting the standard known resistance R3 is called standard arm. The resistance R4 is the unknown resistance to be measured. The battery is connected between A and C while galvanometer is connected between Band D. Directory: wp-content -> uploads -> 2017 2017 -> Leadership ohio 2017 -> Ascension Lutheran Church Counter’s Schedule January to December 2017 2017 -> Board of directors juanita Gibbons-Delaney, mha, rn president 390 Stone Castle Pass Atlanta, ga 30331 2017 -> Military History Anniversaries 16 thru 31 January Events in History over the next 15 day period that had U. S. military involvement or impacted in some way on U. S military operations or American interests 2017 -> The Or Shalom Cemetery Community Teaching on related issues of Integral 2017 -> Ford onthult samenwerking met Amazon Alexa en introduceert nieuwe navigatiemogelijkheden van Ford sync® 3 met Applink 2017 -> Start Learn and Increase gk. Question (1) Name the term used for talking on internet with the help of text messege? 2017 -> Press release from 24. 03. 2017 From a Charleston Car to a Mafia Sedan 2017 -> Tage Participants 2017 -> Citi Chicago Debate Championship Varsity and jv previews Download 3.23 Mb. Share with your friends:
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