Design and Implementation of a Low Cost and Effective Earth Resistivity Meter

The present paper deals with the design and the implementation of a low cost and effective earth resistivity meter. A new earth resistivity meter is proposed as an affordable solution for almost anyone dealing with geophysics, archaeology, hydrogeology, and electricity earth resistance measurement. It is based on the use of a special H bridge configuration, where the power supply is variable, the load current is constant, the upper drive switches of the bridge are opto- isolated, and the lower branches of the bridge are constant current sinks. Based on standard components repair and maintenance of the instrument are possible by qualified technicians. These options have made the instrument simple to implement, as for instance, constant current sinks eliminate the need for current measurement and opto-isolation greatly simplifies circuit design. Although the proposed instrument is intended for use in the Wenner, Schlumberger, dipole-dipole and dipole-pole configurations, some other techniques using resistivity measurement like electric earth resistance are possible. In the present work, tests have been carried out on the Schlumberger configuration, which is known as the most commonly used configuration for underground water investigation. These tests have been performed with the proposed instrument and which have been compared to a standard one. The obtained results show that the reliability of the proposed instrument and the possibility of its exploitation in the above- mentioned fields are satisfactory. © 2021, Editura ELECTRA. All rights reserved.