Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001

13.11.1 Light Dependant Resistors (LDR)

 

· These devices change from high resistance (>Mohms) in the dark to low resistance (<Kohms) in bright light.

 

· The change in resistance is non-linear, and occurs relatively slowly also.

 

· A simple comparator circuit is shown below.

 

 

· This sensor is relatively easy to design with.