COMPUTERIZED_METER

Published:2009/7/10 21:30:00 Author:May | From:SeekIC

With 4.7 megohms for R, simple 555 timer circuit used in conjunction with computer measures capacitors in five ranges from below 100 pF to 0.1 μF. For larger range, resistor value can be changed. Article includes BASIC software suitable for 8080.based FROM PORT our systems, including calibration program based on known values of capacitance. 555 mono MVBR is triggered under control of computer output port bit, with count being made while mono is timing out. Count is averaged over ten triggerings, then multiplied in computer by calibration factor to give capacitance value. Any desired type of output indicator can be used.-J. Eccleston, Computerized Capacity Meter, 73 Magazine, July 1978, p 88-89.



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