The Model 72C Capacitance Meter provides instant, direct reading, three- terminal and differential capacitance measurements from 0.01 to 3000 pF. This coverage is divided into eight ranges, selected either by the front- panel switch or remotely, arranged in a 1 - 3 - 10 sequence. The solid- state design and crystal-controlled signal source contribute to the high stability and excellent reliability of the instrument. The 100 kHz test signal is held to a level of 15 mV, r.m.s., allowing the measurement of capacitance of semiconductor devices. The provision for application of d.c. bias to either or both sides of the specimen makes it possible to measure these devices under operating conditions. The bias voltages can be applied either to the rear-panel terminals provided, or to the appropriate pins on the edge connector. The 72C employs an unusual range-switching system using switching diodes and miniature reed relays; the elimination of the switch contacts from the measurement circuits assures a maximum of reliability and stability. The instrument’s phase-sensitive detector system permits the measurement of even low-Q devices {down to 0-1) without appreciably degrading the accuracy of the measurement* The 72C responds to the effective parallel capacitance of the test specimen. For a specimen with predominantly series loss and a Q-factor of less than 10, the 72C will indicate the effective parallel capacitance; i.e.: Cp = CgQ / (1 + Q ) Two plug-in connection adapters are supplied with the 72C. One adapter, fitted with two sets of coaxial connectors, 72-4B, is intended for use with coaxial cables and remotely located test fixtures for both three-terminal and differential mesurements. The second adapter, 72-5C, with three terminal posts, is used for wire-lead components; differential measurements are not possible with this adapter. A linear d.c. output is available at rear-panel terminals as well as at the appropriate pins on the edge connector. This feature extends the range of applications beyond ordinary laboratory measurements to include production testing as well as a variety of control functions. Flexibility is further enhanced by the provision of remote ranging terminals; the instrument is fully capable of being integrated into a controlled test system for rapid, production-line testing. Remote ranging is controlled by grounding the MANUAL DISABLE terminal on the rear edge connector, disabling the front-panel range switch. Grounding any one of the eight range-line terminals will then select that range.