The Model 72BD Capacitance Meter provides instant, direct-reading, three*-terminal, and differential capacitance measurements from 0.001 to 2000 pF. This capacitance coverage is divided into four ranges, selected by panel pushbuttons, remotely, or autoranged, These are arranged in a 2, 20, 200, and 2000 pF full-scale sequence. The digital display provides 4 digit readout, decimal point, overrange, and pF indications. The solid state design and the low- level crystal-controlled signal source contribute to the high stability and excellent reliability of the instrument. The measurement of semiconductors is facilitated by the 15 mV rms level of the 1 MHz test signal, and by the provision for applying up to 600 volts of dc bias to the test specimen. Bias voltage, of either polarity, may be applied to either or both sides of the specimen. The Model 72BD 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 phase-sensitive detection system permits the measurement of even low-Q devices (down to Q ~ 1) without sensibly degrading the accuracy of the leasurement. Two plug-in test connection adapters are supplied with the Model 72BD. One of these, 72-4B, itted with two sets of coaxial connectors, is intended for use with coaxial cables and remotely ocated test fixtures for both three-terminal and differential measurements. The other adapter, 2.-5C, with two test posts and a ground terminal, is used for wire-lead type components; differen- .ial measurements are not possible with this adapter. A linear dc output is available at rear-panel terminals and at the appropriate pins on the ;ar edge connector. Binary coded decimal outputs are also available at the rear edge connector. ^?se two features extend the range of applications beyond ordinary laboratory measurements to elude production testing and integration into a controlled test system, using logic-level programming. Remote ranging is controlled by grounding the MANUAL DISABLE terminal on the rear edge vector, disabling the front-panel range switches. Grounding any one of the four range-line rminals will then select that range, or auto enable will select autorange.