Controlling LED Intensity with Light Sensors

[zapper]

Hi I would like to know if there is a sensor available in the market that would help control the intensity of light given out by a white LED, taking into account the light coming from the surrounding ambient light. As an example I am trying to implement a project in which I would have to control the intensity of light given out from a white LED which is placed above a computer monitor screen, based on the intensity of light given out from the computer screen, I would have to control the LED light. I would also like to know if the sensor is not available in the market how am I supposed to go about implementing this project.

 

[berkeman]

You can use a Light Dependent Resistor (LDR) to sense the light level:

http://en.wikipedia.org/wiki/Light_Dependent_Resistor

 

[darkwhite87]

A photodiode generates current due to the light intensity that it senses, maybe u can try it.