I am using p89v51rd2 microcontroller with 4 ir sensors for line tracing and 2 color sensors for red and blue color detection. I have used 1k load resistance for all the six sensors. But all the 4 ir sensors shows correct output when connected to controller but the two color sensors alone doesnt show correct output. When it is not connected to controller it shows 4.08V but once it is connected to microcontroller it shows 1.2V or less. Even if i use higher load resistance for those color sensors it doesnt change the output voltage. Is there any other way to solve this problem?? URGENT PLEASE.....

 

We would have to see an accurate schematic before we can help with this.