26-09-2013, 01:00 PM
Light dependent resistors
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INTRODUCTION
Two cadmium sulphide (cdS) photoconductive cells
with spectral responses similar to that of the human
eye. The cell resistance falls with increasing light inten-
sity. Applications include smoke detection, automatic
lighting control, batch counting and burglar alarm sys-
tems.
Light memory characteristics
Light dependent resistors have a particular property in
that they remember the lighting conditions in which
they have been stored. This memory effect can be
minimised by storing the LDRs in light prior to use.
Light storage reduces equilibrium time to reach
steady resistance values.