The Analysis, design and construction of a null detector for a-c impedance bridges.

Note: Author’s signature redacted from title page.When the work of designing and building a null detector was undertaken as a thesis, the initial research was broken up into two phases. The first phase consisted of analyzing the conditions necessary for balancing impedance bridges of various types. The second phase consisted of analyzing the properties necessary for the functioning of a null detector. The bridge is essentially a comparator and its basic property is to attain two equipotential points to compare the bridge arms to each other. The customary types of null detectors used in balancing impedance bridges may be classified under the following headings-, :- (1) Headphones with or without amplification; (2) Tuned vibration galvanometers; (3) A.C. galvanometers of the dynamometer type; (k) D.C. galvanometers of the d’Arsonval type, preceded by suitable rectification; (5) Electronic visual indicators of the cathode-ray oscillograph type. A more detailed discussion of the various types of detectors will be discussed in the following paragraph. Literature on as many types of commercial null detectors as possible was studied. The reasons for the various limitations of these units were studied. The purpose of this thesis was to try to incorporate the best qualities of all of these units into a single unit. An effort was made to overcome these limitations.[...