Boonton Digital Capacitance Meter
(Model 72BD)
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 either by panel push buttons or remotely or auto ranged. These are arranged in 2, 20, 200 and 2000 pF full scale sequence. The digital display provides 4 digit readout, decimal point, over range 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 15mV RMS level of the 1MHz 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.
Model 72BD employs an unusual range-switching system using switching diodes and miniature reed relays; the elimination of the switch contacts from the measurements 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 measurement.
A linear DC output is available at rear panel terminals and at the appropriate pins on the rear edge connector. Binary coded decimal outputs are also available at the rear edge connector. These two features extended the production testing and integration a controlled test system, using logic-level programming.
Specifications:
Capacitance Range: 0.001 - 2000 pF
Full Scale Range: 2, 20, 200, 2000 pF
Resolution: 0.001pF (one digit on lowest range)
Display: LED, 4 digits at approximately 8% over full scale. Decimal points over range indicator and negative polarity
Data Outputs: 1, 2, 4, 8 BCD data, serial by digits. Over range, under range, encode complete and polarity.
DC Output: 2 volts fs adjustable ±2%; source resistance 1000ohms. Linearity 0.1% rdg +0.005%fs. 2000pF range: 0.25% rdg +0.01fs. Response time: 2ms for full accuracy. Noise < 2mV
Power Requirements: 100, 120, 200, 240 V AC, ±10%, 50 - 400 Hz. 13W.
External Bias: HI to GND ±200 V max. LO to GND ±400 V max. LO to HI ±600 V max (floating supply only)
Auto Ranging: Automatically upranges at approximately 2160, downrages at approximately 200. Ranging time is 100 ms per range.
Commands: Logic -level inputs select manual disable, input ranges, auto range, encode hold, and encode trigger, TTL compatible Logic 0 <0.7 V; Logic 1 = 2.4 to 5.25 V.
