Comprehensive Redesign of the DR-74 Instrument for Soil Evaluation Through the Measurement of Electrical Parameters

Abstract

The research addresses the diagnosis and review of the soil resistivity system, an instrument designed to record shallow vertical boreholes through spontaneous, normal, and lateral potential curves. This instrument has presented failures that prevent its proper functioning. The main objective of the research was to identify the causes of the poor performance of the equipment and propose a redesign that increases its accuracy without altering the measurement principle. Based on the theoretical analysis of the four-electrode resistivity system and the review of field records, it was determined that the failures are primarily due to the degradation of the power supply, contacts, and the variation of reference resistances due to aging. A proposal for updating the measurement circuit and current stabilization was developed, preserving the original architecture. This will extend the lifespan of the DR-74 and maintain its reliability in resistivity measurements applied to geotechnical and electrical studies.