Portable_light_level_meter_with_five_decade_dynamic_range

Published:2009/7/24 3:02:00 Author:Jessie | From:SeekIC

This circuit operates from a single cell and is calibrated at midrange with appropriate illumination by adjusting R2 so that output equals the reference, and the meter is 'at center scale. In practical terms, adjust R6 and R2 so the output meter follows a standard light meter. Note that the log slope is not temperature compensated, so there might be error at the scale extremes. Also, silicon photodiodes (D1) are sensitive to near-infrared light, but ordinary film is not. So, an infrared-stop filter is recommended. A blue-enhanced photodiode for D1 or an appropriate correction filter will also produce excellent results.



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