How an LDR (Light Dependent Resistor) Works. LDR (Light Dependent Resistor) An LDR is a component that has a (variable) resistance that changes with the light intensity that falls upon it. This allows them to be used in light sensing circuits.
The electronic symbol of LDR:
The snake like track shown below is the Cadmium Sulphide (CdS) film which also passes through the sides. On the top and bottom are metal films which are connected to the terminal leads. It is designed in such a way as to provide maximum possible contact area with the two metal films. The structure is housed in a clear plastic or resin case, to provide free access to external light. As explained above, the main component for the construction of LDR is cadmium sulphide (CdS), which is used as the photoconductor and contains no or very few electrons when not illuminated.
1. LDR Based light Intensity Control for Street Lights
2. Lighting Switch from Sunset to Sunrise
3. LDR Based light Intensity Control for Street Lights
4. Automatic sun tracker solar system.