Extending the limits of resistance measurement using electronic techniques

In general, this paper is confined to a discussion of devices and techniques which are suitable for inclusion in commercial instruments, rather than of those which, by their complication, delicacy, or specialization, are restricted to the laboratory. It opens with a description of the basic ohmmeter in its two dual forms, refers to three low resistance systems, two using direct and one alternating test currents, and then goes on to describe what is thought to be a novel instrument which can measure very low resistance using pulsed test currents to reduce thermal dissipation in in the test sample. At the very high resistance end of the range where extension has been much greater, the three principal systems are discussed, together with the application of modern devices such as differential constant current generators, electronic stabilizers, dynamic capacitor modulators, and so on; and the paper ends with a detailed description of a widely-used general purpose commercial megohmmeter.