THREE RANGE LIGHT METER


Posted on Feb 5, 2014

Uses probe containing Clairex 905HN light-dependent resistance element, connected to DC differential amplifier driving meter having specially calibrated scale. Article gives calibration procedure. Switching circuit provides constant check on voltage of 22. 5-V battery. If 4. 5-V battery is low full-scale adjustment cannot be made Resistors having


THREE RANGE LIGHT METER
Click here to download the full size of the above Circuit.

values specified in article are connected in turn to terminals of photocell jack P1 for calibration that gives linear scale reading. -J. L. Mills, Jr. , Light Right Do-It-Yourself Photo Exposure Meter, 73 Magazine, Sept. 1978, p 204 206 and 208-211.




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