Hello there,
I am making dimmer using my Arduino Board for my home. I am using LDR for dimming the light. But I am facing one problem that all LDR's are not working identically. I found that every time I am getting different value on same intensity of light using different LDR's. So how can I achieve this?

 

1) Hardware, use resistors to make the LDRs similar
2) Software, Make a look-up table for each LDR
3) Start over, Use a better sensor.

 

Comprehensive, except possibly:
4) Don't worry about it!

 

So how can I achieve this?

By calibrating them to the same output under identical lighting.

 

Hello there,
I am making dimmer using my Arduino Board for my home. I am using LDR for dimming the light. But I am facing one problem that all LDR's are not working identically. I found that every time I am getting different value on same intensity of light using different LDR's. So how can I achieve this?

Any minor change in outdoor light coming into a window will cause a different ADC value. Even reflections of where you are standing relative to lamps and the various reflections in the room - there is lots of possible differences on a minute by minute basis.

 

Any minor change in outdoor light coming into a window will cause a different ADC value. Even reflections of where you are standing relative to lamps and the various reflections in the room - there is lots of possible differences on a minute by minute basis.

You're thinking on a micro scale. I have a drawer full of CdS sensors, and they are so dissimilar that I have to choose which range I want to work in before I start designing. Less than 1k, several k, dozens of k ohms at twilight levels. This range would look problematic to a software program. As an analog designer, I cope with this in hardware. Find the right range, slow down (integrate) the output to discard small interference factors, go to logic section.

 

You're thinking on a micro scale. I have a drawer full of CdS sensors, and they are so dissimilar that I have to choose which range I want to work in before I start designing. Less than 1k, several k, dozens of k ohms at twilight levels. This range would look problematic to a software program. As an analog designer, I cope with this in hardware. Find the right range, slow down (integrate) the output to discard small interference factors, go to logic section.

I just wanted the OP to understand the variabilities within his room with on LDR before tries to match a second to it - what ever his methodology might be or what ever his expectation for his design.