Accession Number : ADA018883

Title :   A new Device for In Situ Measurements of the Complex Rock Resistivity.


Personal Author(s) : Oberladstaetter,Michael ; Nessler,Norbert

Report Date : 27 MAY 1975

Pagination or Media Count : 27

Abstract : A measuring device is described which permits the measurement of magnitude and phase of the complex rock resistivity with the well known Wenner array being applied. The apparatus is composed of the current generator, whose current of the rock and contact resistances to a large extent, the impedance transformers with extremely high-impedance inputs for potential measurements, and the electronic measuring equipment. The latter includes a special differential input amplifier with particularly high common-mode rejection even at high frequencies as well as filters in order to eliminate power supply ripple and HF intersperse. In a highly sensitive phase-sensitive detector the amplitude of the potential difference and the phase between potential difference and applied current are determined. The apparatus operates within 0.01 Hz and 10 kHz with an amplitude accuracy of 1 % and a phase resolution of 1% + or - 0.3 deg. (Author)

Descriptors :   *Rock, *Minerals, *Electrical resistance, *Impedance bridges, Phase measurement, Impedance matching, Alternating current, Electric generators

Subject Categories : Geology, Geochemistry and Mineralogy
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE